Межклеточный рак: стадии, лечение, прогноз, метастазы и первые симптомы

Мелкоклеточный рак легкого — причины, симптомы, диагностика и лечение, прогноз

Мелкоклеточный рак легкого – гистологический тип злокачественной опухоли легких с крайне агрессивным течением и плохим прогнозом. Клинически проявляется кашлем, кровохарканьем, одышкой, болью в груди, слабостью, похуданием; в поздних стадиях – симптомами медиастинальной компрессии. Инструментальные методики диагностики мелкоклеточного рака легких (рентгенография, КТ, бронхоскопия и др.) должны быть подтверждены результатами биопсии опухоли или лимфоузлов, цитологического анализа плеврального экссудата. Хирургическое лечение мелкоклеточного рака легких целесообразно только на ранних стадиях; основная роль отводится полихимиотерапии и лучевой терапии.

Общие сведения

Мелкоклеточный рак легкого относится к числу интен­сивно пролиферирующих опухолей с высоким потенциалом злокачественности. В пульмонологии мелкоклеточный рак легкого встречается значительно реже (15-20%), чем немелкоклеточный (80–85%), однако для него характерны быстрое развитие, обсеменение всей легочной ткани, ранее и обширное метастазирование. В подавляющем большинстве случаев мелкоклеточный рак легкого развивается у курящих пациентов, чаще у мужчин. Наибольшая заболеваемость фиксируется в возрастной группе 40-60 лет. Практически всегда опухоль начинает развиваться как центральный рак легкого, однако очень скоро метастазирует в бронхопульмональные и медиастинальные лимфоузлы, а также отдаленные органы (кости скелета, печень, головной мозг). Без специального противоопухолевого лечения медиана выживаемости составляет не более 3-х месяцев.

Мелкоклеточный рак легкого

Причины

Основной и самой весомой причиной мелкоклеточного рака легкого считается табакокурение, а главными отягощающими факторами — возраст пациента, стаж никотиновой зависимости и количество выкуриваемых в день сигарет. В связи с все большим распространением пагубной привычки среди женщин в последние годы прослеживается тенденция увеличения заболеваемости мелкоклеточным раком легкого среди представительниц слабого пола.

К числу других потенциально значимых факторов риска относятся: наследственная отягощенность по онкопатологии, неблагополучная экология в регионе проживания, вредные условия труда (контакт с мышьяком, никелем, хромом). Фоном, на котором наиболее часто возникает рак легкого, может служить перенесенный туберкулез органов дыхания, хроническая обструктивная болезнь легких (ХОБЛ).

Проблема гистогенеза мелкоклеточного рака легкого в настоящее время рассматривается с двух позиций — энтодермальной и нейроэктодермальной. Сторонники первой теории склоняются к точке зрения, что этот тип опухоли развивается из клеток эпителиальной выстилки бронхов, которые по строению и биохимическим свойствам близки к клеткам мелкоклеточного рака. Другие исследователи придерживаются мнения, что начало развитию мелкоклеточного рака дают клетки APUD-системы (диффузной нейроэндокринной системы). Эта гипотеза подтверждается наличием в опухолевых клетках нейросекреторных гранул, а также повышением секреции биологически активных веществ и гормонов (серотонина, АКТГ, вазопрессина, соматостатина, кальцитонина и др.) при мелкоклеточном раке легкого.

Классификация

Стадирование мелкоклеточного рака по международной системе TNM не отличается от такового при других типах рака легкого. Однако до настоящего времени в онкологии актуальна классификация, выделяющая локализованную (ограниченную) и распространенную стадии мелкоклеточного рака легкого. Ограниченная стадия характеризуется односторонним опухолевым поражением с увеличением прикорневых, медиастинальных и надключичных лимфоузлов. При распространенной стадии отмечается переход опухоли на другую половину грудной клетки, раковый плеврит, метастазы. Около 60% выявленных случаев приходится на распространенную форму (III–IV стадия по системе TNM).

В морфологическом отношении внутри мелкоклеточного рака легких различают овсяноклеточный рак, рак из клеток промежуточного типа и смешанный (комбинированный) овсяноклеточный рак. Овсяноклеточный рак микроскопически представлен пластами мелких веретенообразных клеток (в 2 раза крупнее лимфоцитов) с округлыми или овальными ядрами. Рак из клеток промежуточного типа характеризуется клетками большего размера (в 3 раза больше лимфоцитов) округлой, продолговатой или полигональной формы; ядра клеток имеют четкую структуру. О комбинированном гистотипе опухоли говорят при сочетании морфологических признаков овсяноклеточного рака с признаками аденокарциномы или плоскоклеточного рака.

Симптомы мелкоклеточного рака легких

Обычно первым признаком опухоли служит затяжной кашель, который часто расценивается как бронхит курильщика. Настораживающим симптомом всегда является появление примеси крови в мокроте. Также характерны боли в грудной клетке, одышка, потеря аппетита, снижение веса, прогрессирующая слабость. В ряде случаев мелкоклеточный рак легкого клинически манифестирует с обтурационной пневмонии, вызванной окклюзией бронха и ателектазом части легкого, или экссудативного плеврита.

В поздних стадиях, при вовлечении в процесс средостения, развивается медиастинальный компрессионный синдром, включающий дисфагию, осиплость голоса вследствие паралича гортанного нерва, признаки сдавления верхней полой вены. Часто встречаются различные паранеопластические синдромы: синдром Кушинга, миастенический синдром Ламберта-Итона, синдром неадекватной секреции антидиуретического гормона.

Для мелкоклеточного рака легкого характерно раннее и распространенное метастазирование во внутригрудные лимфатические узлы, надпочечники, печень, кости и головной мозг. В этом случае симптомы соответствуют локализации метастазов (гепатомегалия, желтуха, боли в позвоночнике, головные боли, приступы потери сознания и др.).

Диагностика

Для правильной оценки степени распространенности опухолевого процесса клиническое обследование (осмотр, анализ физикальных данных) дополняется инструментальной диагностикой, которая осуществляется в три этапа. На первом этапе визуализация мелкоклеточного рака легкого достигается с помощью лучевых методов — рентгенографии грудной клетки, КТ легких, позитронно-эмиссионной томографии.

Задачей второго этапа служит морфологическое подтверждение диагноза, для чего производится бронхоскопия с биопсией, плевральная пункция с забором экссудата, биопсия лимфоузлов, диагностическая торакоскопия. В дальнейшем полученный материал подвергается гистологическому или цитологическому анализу. На заключительном этапе исключить отдаленное метастазирование позволяет МСКТ брюшной полости, МРТ головного мозга, сцинтиграфия скелета.

Лечение и прогноз

Четкое стадирование мелкоклеточного рака легкого определяет возможности его хирургического или терапевтического лечения, а также прогнозирование выживаемости. Оперативное лечение мелкоклеточного рака легкого показано только на ранних стадиях (I-II). Но даже в этом случае оно обязательно дополняется несколькими курсами послеоперационной полихимиотерапии. При таком сценарии ведения пациентов 5-летняя выживаемость в рамках данной группы не превышает 40%.

Остальным больным с локализованной формой мелкоклеточного рака легкого назначается от 2 до 4-х курсов лечения цитостатиками (циклофосфан, цисплатин, винкристин, доксорубицин, гемцитабин, этопозид и др.) в режиме монотерапии или комбинированной терапии в сочетании с облучением первичного очага в легком, лимфоузлов корня и средостения. При достижении ремиссии дополнительно назначается профилактическое облучение головного мозга для снижения риска его метастатического поражения. Комбинированная терапия позволяет продлить жизнь больным с локализованной формой мелкоклеточного рака легкого в среднем на 1,5-2 года.

Пациентам с местнораспространенной стадией мелкоклеточного рака легкого показано проведение 4-6 курсов полихимиотерапии. При метастатическом поражении головного мозга, надпочечников, костей используется лучевая терапия. Несмотря на чувствительность опухоли к химиотерапевтическому и лучевому лечению, рецидивы мелкоклеточного рака легких очень часты. В ряде случаев возникшие рецидивы рака легкого оказываются рефрактерными к противоопухолевой терапии – тогда средняя выживаемость обычно не превышает 3–4 месяцев.

прогноз, продолжительность жизни и лечение

Мелкоклеточный рак легкого – форма рака легкого, характеризующаяся образованием злокачественной опухоли с быстрым развитием метастаз в организме.

В отличие от других форм этот вид раковых опухолей является наиболее худшим, возникает редко (в 20% всей численности патологии) и имеет весьма неблагоприятный прогноз.

Так, опухоль – это злокачественное перерождение эпителиальной ткани, которая провоцирует нарушение воздухообмена. Это провоцирует гипоксию и стремительное формирование метастаз. Мелкоклеточный рак легких определяется стремительным течением, в результате чего имеет высокие показатели летального исхода.

Этиология и причины развития

Представленная патология несет для жизни пациента опасность смерти, причем уже в течение первых 2-3 месяцев после диагностирования. Злокачественное преобразование эпителиальных тканей несет за собой быстрое и стремительное формирование и рост опухоли, которая может локализироваться как в самом органе, так и в системе бронхов.

К отличительным характеристикам мелкоклеточной формы относят быстрое метастазирование. Сначала метастазы поражают лимфатическую систему – лимфоузлы. Затем «выходят за пределы», затрагивая внутренние органы и даже спинной и головной мозг человека.

Метастазы

В зависимости от вида опухоли течение заболевания несколько отличается. Так, узелковый характер развития опухоли приводит к поражению легочных артерий, в результате чего их стенки значительно утолщаются. В процессе развития повышается уровень гормонов серотонина, кальцитонина, антидиуретика. Гормональная активность и является причиной образования метастаз.

Быстрое течение заболевания приводит к тому, что практически все больные страдают уже запущенными стадиями – это приводит к отсутствию должного эффекта от лечения.

Развитию смертельно опасной патологии способствует табакокурение, поэтому в большей степени среди заболевших выделяют мужчин в возрасте от 40 до 70 лет. За последние годы стала резко возрастать динамика заболевших мелкоклеточным раком легких среди женщин – это связано с ростом курящих женщин.

Мелкоклеточный рак легкого развивается вследствие следующих причин:

• Табакокурение – основная причина видоизменения клеток легочной ткани;
• Генетический фактор – при наличии родовых проблем с легкими следует быть аккуратным со своим здоровьем и не отягощать состояние курением;
• Длительное поглощение канцерогенов, к которым относят мышьяк, хром и прочие составляющие – этот фактор следует из длительных работ на вредных производствах;
• Туберкулез и прочие заболевания легких – важно вовремя лечить сформированные патологии;
• Воздействие ионов – излучение ионами возможно при атомной катастрофе;
• Плохая экология – загрязненность окружающей среды нередко включает в свой состав те же канцерогены и прочие вредные вещества.

Чтобы максимально уберечь себя от развития мелкоклеточного рака легких, следует обезопасить себя от вредных веществ и отказаться от курения.

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Симптоматика и виды

К симптоматике МРЛ относят:

• сильный сухой кашель;
• постепенное изменение голоса;
• нарушения при приеме пищи – больному тяжело глотать или употребление пищи вообще невозможно;
• недомогания;
• резкая и значительная потеря веса;
• общая слабость;
• боль в груди;
• одышка;
• ломота в суставах и боль в костях.

По мере прогрессирования патологии кашель становится приступообразным и постоянным. Постепенно при кашле начинает отделяться мокрота, в которой заметны прожилки крови. Последние стадии характеризуются увеличением температуры тела. Если опухоль поразила верхнюю полую вену, у больного отмечается нездоровый отек верхней части – лица и шеи. Метастазы зачастую поражают печень, что проявляется развитием желтушки.

Мелкоклеточный рак в зависимости от локализации опухоли подразделяется на следующие виды:

1. Центральный – злокачественная опухоль при таком виде располагается в крупных и сегментарных бронхах.

   Ее тяжело диагностировать, поэтому представленный вид занимает лидирующие позиции по смертности.

2. Периферический – воспаление диагностируется в ткани легкого.
3. Верхушечный – также поражает ткань, но располагается в верхней части, затрагивая бронхиальные ответвления. Опухоль может прорасти в сосуды плечевого пояса и шеи.
4. Полостной – онкологическая опухоль располагается непосредственно в полости легочного органа.

В зависимости от локализации опухоли злокачественного характера зависит ее увеличение и дальнейшее развитие. Так, периферический и верхушечный вид довольно быстро «обрастает» метастазами – это связано с контактом кровеносной системы.

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Стадии

Как и любой рак, легочный рак мелкоклеточной формы подразделяется на 4 стадии. Они прямо указывают особенности и развитие патологии на данный момент течения заболевания:

1. 1 стадия рака – опухоль только левого или правого легкого, ее размеры не более 3 см в диаметре. Метастаз на этот момент еще нет.

2. 2 стадия характеризуется уже увеличенной опухолью до 6 см в диаметре. Увеличенные размеры частично блокируют бронхи, а это чревато развитием сильного приступообразного кашля. Опухоль частично врастает в плевру, в результате чего формируется ателектаз (спадание объема легкого). Зачастую патологию диагностируют именно на 2 стадии, поскольку больной обращается к врачу с жалобами на сильный кашель.

   

   Стадии рака

3. 3 стадия – опухоль увеличивается до 7 см в диаметре, постепенно она переходит в другие органы. На 3 стадии диагностируется полный ателектаз легкого, что значительно затрудняет дыхание и провоцирует гипоксию. Отмечаются первые метастазы в лимфатической системе.
4. 4 стадия мелкоклеточного рака легкого является крайне тяжелой, при которой жить остается не более полугода. Это определяется вследствие значительного распространения онкологических клеток – поражаются соседние и отдаленные органы. При поражении головного мозга больного беспокоят сильные головные боли.

4 стадия определяется серьезным поражением и существенным развитием метастаз в организме человека. В основном здесь выделяют печень – возникает желтушка, кости – ломота в костях и прочие поражения.

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Диагностика

При обнаружении у себя представленных выше симптомов следует немедленно обратиться к врачу, поскольку диагностика патологии на 3 или 4 стадии не приведет к эффективному лечению. К числу диагностических мероприятий относят следующие методы обследования:

1. Флюорографическое обследование – на снимках отображается сформированная опухоль, можно определить ее размеры.
2. Лабораторные исследования крови – при наличии воспалительного процесса и раковых клеток в организме анализ крови укажет повышенное СОЭ и снижение гемоглобина.
3. Бронхоскопические процедуры – производится забор мокроты и отправляется на биохимический анализ в лабораторию, результаты укажут на наличие патогенных микроорганизмов или раковых клеток.
4. Биопсия опухоли – помогает определить злокачественный или доброкачественный характер.
5. Рентген – позволяет увидеть дальнейшие поражения, метастазы и прочий урон, нанесенный организму вследствие возрастания опухоли.
6. КТ и МРТ, прочие инструментальные обследования – дают точную картину формирования опухоли, ее размеров, а также степень осложнений и поражений.

Пациенту важно пройти полное обследование для определения не только раковой опухоли, но и распространения раковых клеток по организму. Это дает возможность назначить курс лечения для поддержания работы и частичного восстановления органов с метастазами. Обследование может дать примерный прогноз на восстановление и эффективность лечения.

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Лечение

Лечение мелкоклеточного рака легких происходит тремя способами, где выделяют:

• Химиотерапию;
• Медикаментозное лечение;
• Хирургическое вмешательство.

В ходе лечения можно примерно дать прогноз на восстановление, продолжительность жизни больного.

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Химиотерапия

Химиотерапия при мелкоклеточном раке легких – это основа всего лечения. Представленная процедура применяется на любых стадиях, а в особенности на 1,2 и 4 стадии. На начальных стадиях уничтожение раковых клеток частично гарантирует предотвращение формирования метастаз. На 4 стадии заболевания химиотерапия может несколько облегчить участь больного и продлить ему еще жизнь.

Химиотерапия при мелкоклеточном раке легкого проводится в качестве основного метода лечения или же в комплексе с дополнительным облучением. Проведя первый курс можно через 2-3 месяца определить прогноз продолжительности жизни.

Локализованный рак правого или левого легкого требует 2-4 курса химиотерапии. Для лечения используются препараты Этопозид, Циклофосфан, Цисплатин и прочие.

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Медикаментозное лечение

Лечение лекарственными препаратами больше направлено на поддержание уже пораженных органов. Здесь назначаются противовоспалительные средства, антибиотики для предотвращения размножения инфекции. Если метастазы обнаружены в печени, назначается препарат для защиты и восстановления клеток – Эссенциале.

При наличии поражения клеток головного мозга используются препараты, насыщающие клетки кислородом – Глицин, из более серьезных Пантогам и прочие.

Как правило, лечение мелкоклеточного рака легких медикаментозно не приносит положительного результата. Даже если заболевание было обнаружено на ранней стадии, избавиться от раковых клеток можно только путем хирургического вмешательства.

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Хирургическое вмешательство

Хирургическое вмешательство используется практически всегда – важно вовремя удалить злокачественную опухоль. При наличии 1 или 2 стадии прогноз на увеличение продолжительности жизни вполне благоприятный.

Для полноценного удаления раковых клеток используется комплексное лечение – удаление опухоли и химиотерапия. При благоприятном исходе больному можно продлить жизнь на 5-10 лет, а то и вовсе справиться с заболеванием.

Если же мелкоклеточный рак легких был обнаружен на 3-4 стадии с наличием обширного поражения внутренних органов организма, специалисты не всегда прибегают к хирургическому вмешательству – велик риск летального исхода еще во время операции.

Для начала больному назначается полноценный курс химиотерапии и лучевое лечение. Частичное устранение раковых клеток и уменьшение метастаз благоприятно влияет на принятие решения об операбельном лечении.

В клинику обратился мужчина 45 лет с жалобами на постоянный сухой кашель без других сопровождающих симптомов простудного заболевания. Пациенту было рекомендовано пройти обследование – сделать снимок флюорографии, сдать кровь на анализ. При рассмотрении полученных данных было обнаружена опухоль в полости легкого размерами в 2,5 см. Анализы крови косвенно указывали злокачественность обнаруженной опухоли. В дополнении были взяты мокрота на лабораторный анализ, а также биопсия самой опухоли.

Результаты показали, что у больного стремительно развивается мелкоклеточный рак легкого, поскольку при наличии кашля мужчина так и не бросил курить.

Больного отправили в стационар в отделение онкологии. Здесь провели курс химиотерапии, в дальнейшем приступили к удалению опухоли. Предотвратив формирование метастаз, специалисты продлили жизнь пациенту. Со дня операции прошло 6 лет, мужчина регулярно проходит обследование, бросил курить, принимает соответствующие лекарства для поддержания организма. Результаты анализов отрицают рецидив, но исключать его полностью нельзя, поскольку ремиссия ракового заболевания может продлиться до 10-15 лет.

Разумеется, при выявлении онкологической патологии больные больше интересуются, сколько живут в подобных случаях. В точности ответить невозможно, поскольку все зависит от обстоятельств, присущих моменту диагностирования заболевания.

При определении опухоли на начальных стадиях выживаемость составляет более 50% с частичной ремиссией и 70-90% с полной. Но если больной отказывается от химиотерапии, он сокращает себе жизнь – в среднем продолжительность оценивается как 10-12 недель при отсутствии своевременного лечения.

Важно регулярно проходить обследования и при возникновении неприятных симптомов обращаться к специалисту. Не стоит отказываться от назначенного лечения после диагностики мелкоклеточного рака легких – эта форма онкологической патологии развивается стремительно, где день промедления может стоить человеку жизни.

Бондаренко Татьяна

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Загрузка… 90000 Targeting Intercellular Communication in Cancer Gene Therapy 90001 90002 1. Introduction 90003 90004 Cells dedicate a considerable amount of energy and regulatory mechanisms to ensure cell-cell communication, for this biological process is an important aspect of their machinery of survival, behavior and fate within their immediate environment. For cells, communicating is vital not only because they are part of organs and tissues of which they contribute to maintaining the integrity and proper function [1-5], but also because many of their functions need to be coordinated, quantitatively fine-tuned and / or limited in space and time.Furthermore, cells make use of communication to minimize the energetic and signaling burden, whereas a single minimal signal could be amplified and propagated, as is for instance the case of gap junction-mediated transfer of pro-apoptotic signals [6-8]. Many types of intercellular communication have been studied, among which direct cell-cell interactions could be distinguished from cellular interactions via released growth factors and cytokines. Their studies have revealed a significant potential for use in cancer therapy.The importance of cell-cell communication is particularly well revealed when defects in this process result in serious diseases, as exemplified by mutations identified in many gap and tight junction proteins [9, 10]. 90005 90004 The diversity of the types of intercellular communications (i.e. gap junctions (GJ), tight junctions (TJ), adherens junctions (AJ) and desmosomes), implicates a diversity of signaling pathways and biological functions at stake. It further emphasizes the need for cells to communicate in different ways and for different purposes: transfer of small molecules, reciprocal signaling, establishment of barriers and polarity, control of paracellular permeability and transmission of cytoskeleton-generated forces.All of these processes have been implicated in cancer development as reviewed previously for GJs [11-13], TJs [14, 15] and desmosomes [16]. 90005 90004 In this chapter we will present an overview of how various types of direct cell-cell communication and different groups of intercellular-dependent protein interactions have been used in strategies of gene therapy of cancer. Important concepts and paradigms as well as successful approaches, limitations and possibilities for the future will be discussed.90005 90002 2. Intercellular communication & gene therapy: The enzyme / prodrug strategy 90003 90004 Cancer gene therapy has since its beginnings faced a major hurdle, the inefficiency of the methods of gene delivery to target cells (i.e. transfection and infection). While attempts have later been made to identify promising alternatives, a key development was the discovery that gap junctions could provide an efficient method that, without directly reaching every cell, could transfer the cytotoxic signal originating from a limited number of target cells to their bystander neighboring cells, thus amplifying the therapeutic effect.This process has subsequently been called «bystander effect» (BE) [17]. Triggering apoptotic death process in target cells results in the transfer of the pro-apoptotic signaling molecules to other cells with which they interact via gap junction intercellular communications (GJICs), and ultimately in the demise of both cells. The BE thus plays an important role in the efficiency of cancer therapy [18]. It also impacts the therapeutic cytotoxic side effects: since high doses of drugs are not required to kill tumor cells, normal tissues may not be reached by the treatment.90005 90014 Figure 1. 90015 90004 The enzyme / prodrug system and the bystander effect. Delivery via viral or non viral vectors of DNA sequences expressing an enzyme, here the herpes simplex virus thymidine kinase gene (TK) in the presence of the prodrug inactive substrate, here ganciclovir (GCV), results in the synthesis of the active metabolite, here GCV triphosphate (GCV-tp), which kills not only the target cell, but the neighboring bystander cell as well. This ‘bystander effect’ is mediated by a direct transfer of cytotoxic signals through gap junctions (GJ) -mediated intercellular communication.90005 90002 3. Use of the bystander effect in the enzyme / prodrug cancer gene therapy 90003 90004 Gene therapy soon became the major therapeutic application of the BE in the so-called «suicide gene therapy» involving the use of Enzyme / Prodrug cytotoxic systems, whereby target cells express an enzyme that converts a prodrug into the cytotoxic active drug, which is then transferred via gap junctions to the interacting cells [19]. The general mechanism is that the active molecules are therefore transmitted to neighboring cells via GJIC and trigger their death [20].GJIC and connexins are essential for the BE-based enzyme / prodrug therapy [21-26] (Figure 1). Different enzymes / prodrugs have been assayed among which cytosine deaminase (CD) / 5-fluorocytosine (5-FC), carboxylesterase / Camptothecin, and Herpes Simplex Virus-thymidine kinase (HSV / tk) / Ganciclovir (GCV) are prominent [27] . The CD / 5-FC combination is based on the conversion of the nontoxic prodrug 5-FC by bacterial or yeast enzyme cytosine deaminase into active 5-fluorouracil (5-FU) [28]. Similarly, GCV, a nontoxic purine analogue, is phosphorylated by the enzyme HSVtk and by endogenous kinases to GCV-triphosphate, which kills cells by inhibiting DNA synthesis [29] [30].The carboxylesterase activates the prodrug irinotecan, 7-ethyl-10- [4- (1-piperidino) -1-piperidino] carbonyloxycamptothecin (CPT-11) to the active metabolite SN-38. Another combination including the uracil phosphoribosyltransferase (UPRT) of E. coli and 5-fluorouracil (5-FU), has also been used in BE-based gene therapy, along with other less known systems. UPRT is an enzyme that catalyzes the synthesis of UMP from uracil and 5-phosphoribosyl-alpha-1-diphosphate [31]. 90005 90004 The therapeutic potential of the HSVtk and nucleosides ‘combination has been assayed as early as the 70’s and later extended to many types of cancers both 90023 in vitro 90024 and 90023 in vivo 90024 [32-41].Originally tried using retroviral vectors, the same approach adapted to adenoviral vectors was later introduced and used successfully [42-44]. These and subsequent studies, all have in common the use of an efficient delivery system, mostly adenoviral, modified to improve the transduction efficiency or selectivity, in combination with an enzyme / prodrug system, most often the HSVtk / GCV, to achieve cancer cells ‘ cytotoxicity. Virus-free delivery has also been attempted using liposomes for instance, with more or less good efficacy [45-47], but most of the studies have used viral delivery.90005 90028 3.1. Combination of oncolytic viruses and enzyme-prodrug gene therapy 90029 90004 Viruses are preferred vehicles for the transfer and delivery of engineered genes into host cells in gene therapy approaches. Recently, they have emerged as not only delivery vectors, but as 90023 bona fide 90024 therapeutic agents [74-77] (Figure 2). Oncolytic replication-competent viruses infect, replicate in and kill tumor cells. Examples abound of attempts to combine gene therapy and oncolytic virotherapy.Furthermore, the enzyme / prodrug systems have been used to improve the anti-tumor efficacy of oncolytic viruses. Early studies addressing the use of HSV vectors as oncolytic agents, showed that HSV-mediated oncolysis is enhanced by ganciclovir treatment through bystander effect [78]. A recombinant HSV (M012) was constructed to express the bacterial CD gene and was shown to enhance the prodrug-mediated anti-tumor effects after intracranial delivery in murine neuroblastoma and human glioma cells [79].An oncolytic adenovirus modified to bear the human telomerase promoter (hTERT), was used to deliver the gene for the prodrug-activating enzyme carboxypeptidase G2 (CPG2) to tumors. The CPG2 metabolizes the prodrug ZD2767P into a cytotoxic drug and this strategy was shown to be effective in colorectal carcinomas via bystander effects and induction of apoptosis [80]. A recombinant Vesicular stomatitis virus (rVSV) encoding the CD / UPRT fusion gene was delivered intratumorally in the presence of the systemically administered 5-FU and significantly reduced growth of lymphoma and breast cancer cells 90023 in vivo 90024.This effect involved three mechanisms: a strong bystander effect, the viral oncolytic activity as well as the activation of the immune system against the tumor [81]. Recombinant vesicular stomatitis virus (VSV) made to express CD / UPRT was delivered to breast cancer cells in combination with 5-fluorocytosine (5FC) [82]. An oncolytic adenovirus Ad5 / 3-Delta24FCU1 expressing the fusion suicide gene FCU1, which encodes a bifunctional fusion protein that metabolizes 5-FC, was found to exert significant anti-tumor activity 90023 in vitro 90024 and 90023 in vivo 90024 in a murine model of head and neck squamous cell carcinoma [83].ONYX-015 (90023 dl 90024 1520), a conditionally replicating adenovirus (CRAd) made of an E1B-55k-deleted oncolytic adenovirus and which has anti-tumor effects [84], has been combined with the CD / 5-FC system and the enzyme / prodrug system involving 90023 E. coli 90024 nitroreductase (NTR) which can reduce nitro (hetero) aromatic compounds to hydroxylamines and amines, and both combinations showed enhanced efficacy 90023 in vitro 90024 and 90023 in vivo 90024 [85, 86]. Similarly, an oncolytic measles virus (MV) armed with the prodrug convertase, purine nucleoside phosphorylase (PNP) and the prodrug 6-methylpurine-2’-deoxyriboside (MeP-dR), was tested in a model of murine colon adenocarcinoma cells in syngeneic C57BL / 6 mice and shown to have anti-tumorigenic effects after systemic delivery [87].In spite of this available literature, many questions remain open. The factors defining the efficacy of this combinatorial therapy are not clearly identified and the strategy might not have any advantage in certain contexts. For instance, an oncolytic adenovirus, selective for the Rb / p16 pathway, killed ovarian cancer cells effectively by Tk / GCV-driven BE. However, while GCV improved the adenoviruses ‘antitumor efficacy over the replication-deficient virus counterpart, it did not further enhance its efficacy 90023 in vivo 90024, suggesting that the prodrug strategy may not add antitumor activity to highly potent oncolysis [88].90005 90028 3.2. Combined use of the enzyme / prodrug cancer gene therapy and gap junction communication restoration 90029 90004 Although since the beginning of the use of the enzyme / prodrug approach, it was found that the BE involves effects that do not depend on direct cell-cell interaction and are rather related to diffusible molecules released extracellularly and possibly to immune-related effects [48-51], the role of gap junctions-mediated intercellular communication (GJIC) and connexins was deemed essential [25, 26, 52-54] [55] .In light of the observed loss of connexins ‘expression in many cancers, the efficiency of the enzyme / prodrug approach could be limited by the ability of tumor cells to undergo GJICs between gene-transduced and bystander non-transduced cells. The levels of connexins and GJIC could modulate the impact of the bystander effect of the prodrug / enzyme systems, as shown for HSVtk / GCV 90023 in vitro 90024 and 90023 in vivo 90024 [56, 57]. This was suggested to be a reason behind the limited efficacy of the viral HSVtk / GCV delivery in many reports [58-60].Nevertheless, many attempts have been made to bypass this limitation by restoring connexins ‘expression and the ability to undergo GJIC. This could be achieved either by the direct delivery of Cx-encoding vectors [61-64] or by pharmacological induction of Cx expression. The later approach involved for instance treating with DNA demethylating agents [65], histone deacetylases ‘inhibitors (HDACi) [66-68], ATP-sensitive potassium (KATP) channels’ inhibitors [69], treatment with all-trans retinoic acid [ 70] or cyclic-AMP [71-73].90005 90028 3.3. Applications of the enzyme / prodrug gene targeting of stem cells 90029 90004 Cellular vectors, including stem cells, have been used for effective gene delivery in cancer therapy. Stem and progenitor cells have been acknowledged as important for both normal and cancer homeostasis. In particular, according to the cancer stem cells ‘theory, tumors contain a very small sub-population of self-renewing and highly proliferating cells called cancer stem cells (CSCs), which are responsible for the tumorigenic activity [89].Mesenchymal stem cells (MSCs), which have a strong tropism for tumor cells, are another type of stem cells of importance in cancer understanding and therapeutic targeting [90]. The use of allogeneic and hence escaping immune vigilance mesenchymal stromal cells (MSCs), sometimes called mesenchymal stem cells, as Trojan horses to deliver the enzyme / prodrug within the tumor mass is a relatively new development in gene therapy. MSCs are used as carriers of the enzyme via viral transduction, which subsequently activates the prodrug and kills not only the MSCs but their neighboring cancer cells (Figure 2).This strategy has been tested in many cancers, as illustrated by the following examples. 90005 90004 It has been shown that MSCs localize primarily to the perivascular environment in many organs and, when implanted or injected into animals, they show a tropism for primary tumors and metastases, and specifically for the perivascular niches within tumors [91, 92]. Based on this preferential migration, MSCs have been used as a vehicle in gene therapy strategies [93, 94]. The cytosine deaminase prodrug system has been partnered with the human MSCs and the combination increased the bystander effect and selective cytotoxicity on target tumor cells 90023 in vitro 90024 and 90023 in vivo 90024 [95-97].Similarly, human neural stem cells (NSCs) have been successfully used to therapeutically target brain cancers. In fact, both MSCs and NSCs show high tropism for brain cancers and have been combined with the prodrug system to target brainstem gliomas, a form of childhood central nervous system tumors with poor prognosis or medulloblastomas [98-101], and even in disseminated brain metastases of non-neuronal origins such as melanoma and breast cancer [102-104]. The success of this approach now warrants clinical trials such as the one recently started to study the feasibility of intracerebral administration of NSCs in combination with oral 5-FC in patients with recurrent high-grade gliomas [105].90005 90004 Based on the tropism shown by neural stem cells (NSCs) for glioma cells, the herpes simplex virus-thymidine kinase (HSVtk) / GCV system has also been used in targeting gliomas [106-108]. However, for practical reasons related to the availability of cells, the use of MSCs might be more relevant clinically than the use of NSCs [109]. The system has also been tested for AT-MSCs [110] and bone marrow-derived tumor-infiltrating cells (BM-TICs) targeting of gliomas [111]. It was also proven to have a strong anti-tumor growth in medulloblastomas [112].90005 90004 As discussed earlier, a major limitation to the efficacy of the therapeutic use of GJIC is the deficiency in the bystander effect due to low expression levels of connexins. Expectedly, this is also a challenge when using the prodrug / stem cells combined therapy. This can be bypassed by restoring connexin levels. For instance, GSCs showed more reduced GJIC and connexin levels than differentiated glioma cells [113]. Valproic acid (VPA) was able to upregulate Cx43 and Cx26 and to enhance the bystander effect of suicide gene therapy by human bone marrow MSCs expressing HSV-TK (MSCs-TK) [114].In another study, the use of Bone marrow-derived stem cells (BMSCs) in combination with the (HSV-TK) / GCV suicide gene therapy of gliomas was improved by Cx43 overexpression 90023 in vitro 90024 and 90023 in vivo 90024 [115]. 90005 90004 The MSC / Prodrug and Oncovirus / Prodrug strategies are often combined. For instance, MSCs transduced with an adenoviral vector modified to express integrin-binding motifs (Ad5lucRGD) for better transduction efficiency, and expressing thymidine kinase were able not only to kill ovarian cancer cells via bystander effect, but also support replication of adenoviruses which could result in further sustaining the effect [116].90005 90004 MSCs can also act through an anti-angiogenic mechanism. They have been shown to target endothelial cells and inhibit capillary growth, establish Cx43-based GJIC with the target ECs, and to increase the production of reactive oxygen species (ROS). This effect culminates in the induction of apoptosis, thus inhibiting tumor growth in a model of melanomas [117]. 90005 90014 Figure 2. 90015 90004 Different approaches of intercellular communication-based gene therapy. Tumor cells (TC) are targeted with oncolytic viruses which, in addition to their proper cytotoxic effects [1], could be combined with the bystander effect ensured by the enzyme / prodrug system, here for example the TK / GCV pair [3].TCs are made sensitive to the bystander effect cytotoxic effects by inducing connexin (Cx) expression and the formation of gap junction intercellular communication. This is achieved by either 4) viral vectors, or 5) pharmacological inducers. Cellular delivery of the viral vectors for the enzyme / prodrug system could also be achieved using mesenchymal stem cells (MSCs) and other types of stem / progenitor cells [6]. 90005 90028 3.4. The enzyme / prodrug approach in non-gap junctional communications 90029 90004 Curiously, unlike gap junctions, the number of studies delivering tight and adherens junctions or desmosomal proteins for cytotoxic gene therapy is limited.The adenoviral delivery of TK and E-cadherin genes improved TK / GCV cytotoxicity and antitumoral activity in pancreatic cancer cells [118]. 90005 90004 Nevertheless, other cell-cell adhesion proteins, either or not with known links to these junctions, have been targeted in the enzyme / prodrug approach, as illustrated by the following examples. Carcinoembryonic antigen (CEA), a glycoprotein involved in cell-cell adhesion as well as cell-extracellular substrate adhesion, is a particularly prolific case.The expression of CEA in cancer cells with the exclusion of adult normal cells has been used in multiple ways to provide specificity to the Enzyme / Prodrug system. This directed enzyme / prodrug therapy, involves the generation of a recombinant plasmid, containing CEA promoter to specifically drive the expression of the enzyme / prodrug systems in CEA-expressing cancer cells [119-121]. The E. coli purine nucleoside phosphorylase (ePNP) under the control of CEA promoter sequences greatly improved the antitumor efficacy of the ePNP / MePdR killing system in pancreatic cancer cells [122].The use of the double system including TK / GCV and CD / 5-FC, in CEA-positive lung cancer cells, resulted in enhanced cytotoxicity [123]. A CEA promoter-regulated oncolytic adenovirus vector driving the Hsp70 gene expression in CEA-positive pancreatic cancer cells was also active 90023 in vitro 90024 and 90023 in vivo 90024 [124]. Similar results were obtained by targeting suicide gene CD expression to colon cancer cells [125]. An E1A, E1B double-restricted oncolytic adenovirus, AxdAdB-3, improved the therapeutic efficacy of the HSVtk / GCV system in gallbladder cancers when directed by the CEA promoter [126].A modification of the approach done earlier, involved the addition of four tandem-linked NF-kappaB DNA-binding sites (kappaB4) and a kappaB4 enhancer upstream of the CEA promoter, thus sensitizing colon cancer cells to the thymidine phosphorylase (TP) / 5 -fluorouracil (5-FU) or 5′-deoxy-5-fluorouradine (5’-DFUR) combinations [127]. A different way of targeted delivery of adenoviral vectors involved the generation of a bispecific adapter protein (sCAR-MFE), consisting of a fusion of the ectodomain of the coxsackie / adenovirus receptor (sCAR) with a single-chain anti-CEA antibody (MFE -23) [128].A specific CEA RNA-targeting ribozyme was developed and used for selective delivery of HSVtk / GCV cytotoxic activity, into CEA-expressing cancer cells [129]. 90005 90004 A high affinity antibody for Neural cell adhesion molecule 2 (NCAM2), a cell-cell adhesion molecule, which is also capable of cell-extracellular matrix adhesion, was useful in increasing transduction efficiency of a fiber-modified adenoviral vector Adv-FZ33 in prostate and breast cancers, and restoring sensitivity to the UPRT / 5-FU system in previously resistant cells [130].An Adenoviral vector incorporating an IgG Fc-binding motif (Z33) from the Staphylococcus protein A (Ad-FZ33) combined with tumor-specific anti-EpCAM (epithelial cell adhesion molecule) antibodies improved the viral transduction and the growth suppression of biliary cancer xenografts in nude mice in response to the UPRT / FU combination in human biliary cancers [131]. A similar approach used the enzyme / prodrug system comprised of the enzyme carboxylesterase (CE) and its substrate the anticancer agent CPT-11 (irinotecan or 7-ethyl-10 [4- (1-piperidino) -1-piperidino] carbonyloxycamptothecin).An adenoviral vector Ad.C28-sCE2 containing a fusion gene encoding a secreted form of human liver CE2 targeted to EpCAM was efficient in colon cancer spheroids [132]. As for CEA, the validation of the use of the EpCAM promoter to target the HSVtk / GCV therapy to cancer cells has been performed [133]. 90005 90002 4. Gene therapy using bystander effect-independent intercellular communications 90003 90004 The prominence of BE-based gene therapy in the literature should not eclipse the importance of other intercellular communications which do not involve the BE as candidates for gene therapy.These include in addition to a GJIC-independent role of connexins, other types of cell-cell junctions as well as other types of protein-protein (ligand-receptor) interactions who depend on cell-cell interactions for their functions. Although to different extents, all these intercellular events have proven very amenable to gene therapy strategies. 90005 90028 4.1. GJIC-independent effects 90029 90004 The key players in the BE are connexins, the building blocks of gap junctional intercellular communication (GJIC) [23, 134, 135].Even though the effectiveness of restoring Connexins ‘and GJIC’s levels has traditionally been associated with the bystander effect in gene therapy, it has become clear that many functions of connexins, could be dissociated from both GJIC and the bystander effects [136-138] [139 ] [140] [141]. In this case, delivery of Cxs-encoding vectors could be used as a gene therapy approach, regardless of the use of enzyme / prodrug systems. However, future use of such application requires a better understanding of the non GJIC-related functions of these proteins, including their interacting partners and the mechanisms of their subcellular localization.90005 90028 4.2. Desmosomes, adherens and tight junctions in gene therapy 90029 90004 Adherens junctions and their related desmosomes, as well as tight junctions are essential types of cell-cell adhesion in both normal homeostasis and tumor progression [142-148]. Claudins are key tight junction proteins whose expression is deregulated in many cancers [146, 149]. Claudins CLDN3 and CLDN4 function as receptors for the Clostridium perfringens enterotoxin (CPE) produced by the bacterial Clostridium type A strain, resulting in cell death.A gene therapy application based on CPE gene transfer-mediated cytoxicity has been achieved but, as expected, was limited to CLDN3- and CLDN4-overexpressing tumors [150]. SiRNA-mediated silencing of the expression of Epithelial Cell Adhesion Molecule (EpCAM or CD326), a cell-surface protein involved in tight junctions and metastasis in colon, breast and other epithelial carcinomas, was effective in decreasing the growth of breast cancer cells [151 ]. The same approach was used with an antibody against the carcinoembryonic antigen (CEA) in gastric cancer [152].In fact, CEA has been extensively targeted in gene therapy approaches in different ways. A recombinant form of the oncolytic measles virus Edmonston strain (MV-Edm) changed to express CEA, demonstrated high cytotoxicity towards hepatocellular carcinoma cells 90023 in vitro 90024 and 90023 in vivo 90024 after either Intratumoral or intravenous delivery [153]. The cell adhesion molecule CECAM1, or carcinoembryonic antigen-related cell adhesion molecule 1, has served in an adenoviral gene therapy targeting prostate cancer cells and showed tumor suppressor activities 90023 in vivo 90024 [154].90005 90004 It is noteworthy that even when targeting these cell-cell communications could not be directly performed or if it fails to affect tumor growth, there is no doubt about their impact on gene therapy applications. Cell-cell communications could indeed constitute a source of impediment to gene therapy, by constituting physical barriers to tumor targeting with oncolytic viruses 90023 in vivo 90024 [155] [156, 157]. This is particularly important in tissues such as the lung, intestine and reproductive system which show natural mechanisms of resistance to viral infection and might thus be less amenable to viral gene delivery.In fact, many junction proteins have been shown to be receptors for many viruses. The protein originally known as coxsackie-adenovirus receptor (hCAR), which was used in adenoviral-based gene therapy for cancer before realizing that it is a component of epithelial tight junctions [158, 159], affects the efficacy of the adenoviral gene therapy approach [160, 161]. Desmoglein-2 (DSG-2), a desmosomal adhesion glycoprotein, is a receptor used by adenoviruses Ad3, Ad7, Ad11 and Ad14, which subsequently results in epithelial-to-mesenchymal transition-like changes and transient opening of intercellular junctions, a finding that could have an impact on the adenoviral gene delivery to normal or cancer cells [162, 163].Adherens junction proteins Nectin-1 and -2 are entry receptors for the herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) [164-166]. Increasing Nectin-1 expression resulted in increased susceptibility to HSV-1 infection and oncolytic activity and hence enhanced tumor regression 90023 in vivo 90024 [167]. Attenuated HSV-2 viral production in WB rat liver epithelial cells was found to depend on the viral protein co-localization with adherens junction proteins rather than by the status of gap junctions [168].Taken together, these studies demonstrate the importance of junctional proteins in the infectivity of viruses and suggest that they might impact the efficacy of the viral oncolytic gene therapies. Compounds could thus be identified for example to improve viral gene transfer [169]. 90005 90028 4.3. Intercellular communications-dependent protein-protein interactions 90029 90004 Many proteins, although not 90023 bona fide 90024 components of cell-cell junctions, are either affected by these interactions or are very important in the function of direct cell-cell interactions, whether junctional or not .Prototypes of these proteins are the ones involved in axon guidance, such as the Eph / Ephrin proteins. The Eph family is the largest family of receptor tyrosine kinases, and includes the A-type Eph (EphA1-10) and B-type Eph (EphB1-6) receptors as well as A-type Ephrin (EphrinA1-6) and B- type Ephrin (EphrinB1-3) ligands. A particularity of this family is that, with few exceptions, the receptor-ligand interactions depend on direct cell-cell contacts, as both Ephs and Ephrins are anchored in interacting cellular membranes and in fact their role in cell-cell repulsion / attraction and cell sorting is one of their main features.Study of Ephs / Ephrins ‘role in cancer has dramatically boomed in the last decade [170] and attempts are currently underway to target them in cancer therapy. Targeting of Ephs and Ephrins for gene therapy has been very timid so far. EphA2 is probably one of the most sought after receptors of this family, as its expression is increased in many cancers and it has shown pro-oncogenic functions. A human adenoviral type 5 (HAd) vector expressing a secreted fusion protein constituted of the extracellular domain of EphrinA1, an EphA2 ligand, fused to the Fc portion of IgG1, was used to infect mammary epithelial cells and was found to activate and induce the degradation of EphA2, thus showing anti-tumor effects.After intratumoral inoculation, the HAd-EphrinA1-Fc vector significantly inhibited tumor growth 90023 in vivo 90024 [171, 172]. On the other hand, taking advantage of the high expression levels of EphA2 in cancer cells, an EphA2-binding peptide has been added to an Adenoviral vector (Ad) to target pancreatic cancer cells and bypass the limitation of low Ad transduction due to low levels of the major Ad receptor called Coxsackie and Ad receptor (CAR) [173]. Recently, EphA2 has been shown to be an essential receptor for the Kaposi’s sarcoma-associated herpesvirus, a major oncogenic virus in endothelial cells [174, 175].EphrinB2 and EphrinB3, other family members, have also been identified as entry receptors for the Hendra virus and Nipah virus [176-178]. These data suggest that interfering with Ephs and Ephrins could be an interesting strategy in gene therapy applications by improving the transduction of viral vectors. 90005 90002 5. Concluding remarks & perspectives 90003 90004 Over the years, it has become clear that various systems of cell-cell communication play critical roles not only in the normal development, architecture, remodeling and function of various tissues and organs, but in the onset of diseases as well.Cells are social entities and need to interact with each other in a way that ensures a favorable response to input from their immediate micro-environment (growth, survival, cytotoxicity) and a flexible adaptation to various roles and stress conditions. They also need to communicate during their death and demise. These communication processes are subject to various regulatory mechanisms which, when going awry, could result in various pathologies. One such instance where cell-cell communication has a particularly dramatic role is cancer progression, metastasis and response to therapeutic interventions.This reliance of cancer cells on cell-cell communication provides a therapeutic opportunity that will be fully exploited only if the mechanisms of its normal and aberrant functions are elucidated. This is for instance obvious when attempting to restore GJIC to render cancer cells sensitive to enzyme / prodrug therapies. 90005 90004 Also, cancer cells share their microenvironment with many other cell types who are not just neutral bystanders. In particular, invasive cancer cells have very unstable intercellular contacts, as they keep migrating, constantly adhering to and detaching from cells on their way and thus changing the nature of their cell-cell communications.This might be a challenging fact when thinking of gene therapy strategies, and in fact any other type of therapy. Thus understanding these dynamics of change during the course of tumor progression is of utmost importance. 90005 90004 As progress continues in developing strategies for a more efficient and selective viral delivery of gene therapeutics, the role of different junctions in the resistance of cancer epithelial cells to viral infections, needs to be balanced by the advantageous use of these proteins to render this approach more cancer-specific.In this respect, the enzyme / prodrug strategies need to be reconsidered in the light of the new findings that involve both gap junctions and other types of intercellular communications in the bystander effect. Examining the links between the different types of cell-cell communication will be critical for future applications. 90005 90004 Finally, the impact of protein-protein interactions which are not necessarily engaged in cell junctions but are involved in direct cell-cell interactions, and the therapeutic opportunities they provide, will constitute a way for the future.90005.90000 Just a moment … 90001 90002 Please enable Cookies and reload the page. 90003 90004 This process is automatic. Your browser will redirect to your requested content shortly. 90003 90006 Please allow up to 5 seconds … 90003 90008 + ((! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + !! [] + !! [] + []) + (! + [] + (!! []) + !! [] + !! []) + (+ !! []) + (! + [] — (!! [])) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + !! []) + (! + [] + (!! []) + !! []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [ ] + !! [] + !! []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + !! []) + (+ !! [])) / + ((! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + !! [] + !! []) + (! + [] + (!! []) — []) + (! + [] + (!! []) — []) + (! + [] + (!! []) + !! []) + (+ !! []) + (! + [] + (!! []) + !! [] + !! [] + !! []) + (+ !! [] ) + (! + [] + (!! []) + !! [] + !! [])) 90003 90008 + ((! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + !! [] + []) + (! + [] + (!! []) + !! []) + (! + [ ] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + !! []) + (! + [] —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— []) + (! + [] + (!! []) + !! [] + !! [] + !! [])) 90003 90008 + ((! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + !! [] + []) + (! + [] + (!! []) + !! []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + !! []) + (! + [] — (!! [])) + (! + [] + (!! []) + !! [] + !! []) + (+ !! []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! []) + (! + [] + (!! []) + !! [] + !! [] ) + (+ !! [])) / + ((! + [] + (!! []) — [] + []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + !! []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! []) + (! + [] + (!! []) + !! [] + !! []) + (! + [] + (!! [ ]) + !! [] + !! [] + !! []) + (! + [] + (!! []) —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— (!! [])) + (! + [] + (!! []) + !! [])) / + ((! + [] + (!! []) + !! [] + !! [] + !! [] + !! [ ] + []) + (+ !! []) + (! + [] + (!! []) + !! []) + (+ !! []) + (! + [] — (!! [])) + (! + [] + (!! []) + !! [] + !! [ ] + !! [] + !! [] + !! []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + !! []) + (! + [] — (!! [])) + (! + [] — (!! []))) 90003 90008 + ((! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + !! [] + []) + (! + [] + (!! []) + !! []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + !! []) + (! + [] — (!! [])) + (! + [] + (!! []) + !! [] + !! []) + (+ !! []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! []) + (! + [] + (!! []) + !! [ ] + !! []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [])) / + ( (! + [] + (!! []) + !! [] + !! [] + []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] +! ! []) + (+ !! []) + (! + [] + (!! []) + !! []) + (! + [] — (!! [])) + (! + [ ] + (!! []) + !! []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! []) + ( + !! [])) 90003 90008 + ((! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] +! ! [] + !! [] + []) + (! + [] + (!! []) — []) + (! + [] — (!! [])) + (! + [] + (!! []) + !! [] + !! []) + (+ !! []) + (! + [] + (!! []) + !! [] + !! [] +! ! [] + !! [] + !! [] + !! [] + !! []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + !! []) + (! + [] + (!! []) — []) + (! + [] + (!! []) +! ! [])) / + ((+ !! [] + []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [ ] + !! [] + !! [] + !! []) + (! + [] + (!! []) — []) + (+ !! []) + (! + [] + ( !! []) — []) + (! + [] + (!! []) + !! [] + !! []) + (! + [] + (!! []) + !! [ ] + !! [] + !! []) + (! + [] — (!! [])) + (! + [] + (!! []) + !! [] + !! [] + !! [])) 90003 90008 + ((! + [] + (!! []) + !! [ ] + !! [] + !! [] + !! [] + !! [] + !! [] + !! [] + []) + (! + [] + (!! []) +! ! [] + !! []) + (+ !! []) + (! + [] — (!! [])) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + !! []) + (! + [] + (!! []) + !! []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + !! [] + !! []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + !! []) + (+ !! [])) / + (( ! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + []) + (! + [] + (!! []) +! ! [] + !! []) + (! + [] + (!! []) —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— (!! [])) + (! + [] + (!! [ ]) + !! [])) / + ((! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] + []) + (! + [] + (!! []) + !! [] + !! [] ) + (! + [] + (!! []) + !! []) + (! + [] + (!! []) + !! [] + !! [] + !! []) + (+ !! []) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! []) + (! + [] — (!! [])) + (! + [] + (!! []) + !! [] + !! [] + !! [] + !! [] + !! [] +! ! [] + !! []) + (! + [] + (!! []) — [])) 90003 90008 + ((! + [] + (!! []) + !! [] +! ! [] + !! [] + !! [] + !! [] + !! [] + []) + (+ !! []) + (! + [] + (!! []) +! ! [] + !! [] + !! [] + !! [] + !! []) + (! + [] + (!! []) + !! [] + !! [] + !! []) + (! + [] — (!! [])) + (! + [] + (!! []) + !! [] + !! []) + (! + [] + (! ! []) —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—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ntercellular space — wikidoc 90001 90002 90003 Editor-In-Chief: 90004 Henry A. Hoff 90005 90002 Cells are the fundamental units of all known living organisms. Humans have an estimated 100 trillion or 10 90007 14 90008 cells; a typical cell size is 10 μm; a typical cell mass is 1 ng. 90005 Cells in culture, stained for keratin (red) and DNA (green), with a small breadth between each cell. 90002 A space located or occurring between cells is often referred to as an 90003 intercellular space 90004.When the space is passing a cell, or cell membrane or situated beside or between cells the term 90003 paracellular space 90004 is usually used. Epithelial cells are packed tightly together, with almost no intercellular spaces and only a small amount of intercellular substance. 90005 90002 An intercellular space probably can be reduced to that remaining as one membrane physically touches that of its neighboring cell. But, often cells express transmembrane proteins. 90005 Illustration of a cell membrane with transmembrane proteins extending into paracellular space.90002 In order for such transmembrane proteins to function some separation distance between cell membranes must be maintained. 90005 90020 Intercellular fluid 90021 90002 Intercellular fluid is composed of water and small soluable molecules. Glucose, oxygen and amino acids diffuse into the spaces around the cells from the capillaries. Plasma leaves the capillaries and flows into the intercellular spaces between the cells of the tissues to be part of the fluid that surrounds those cells. 90005 90002 The space between any two cells generally is roughly a thin two dimensional sheet or layer of thickness or breadth typical for the cells involved.Fenestrated capillaries have pores in the endothelial cells (60-80 nm in diameter) that are spanned by a diaphragm of radially oriented fibrils and allow small molecules 90007 [1] 90008 and limited amounts of protein to diffuse. The paracellular breadth between cell membranes juxtaposed by tight junctions appears to be <5 nm. In a gap junction the intercellular space is reduced from 25 nm to a ~ 2-4 nm wide paracellular space. The width of the intercellular space between cells with desmosomes between them is very wide (about 30 nm).A 10 nm diameter corresponds to an upper mass limit of 70 kDa. 90007 [2] 90008 90005 90002 Using the water (data page) and the atomic radii of the elements (data page), a water molecule is approximately 120 x 187 pm in maximum diameters (average 154 pm). This suggests the minimum number of water layers in say 3 nm is ~ 20. For the two most likely phosphates in solution, H 90031 2 90032 PO 90031 4 90032 90007 1 90008 and HPO 90031 4 90032 90007 2 90008, the average diameters are about 413 pm and 406 pm, respectively.This suggests about 7 P 90031 i 90032 layers in 3 nm. 90005 90002 90003 Capillaries 90004 measure 5-10 μm in diameter and enable the interchange of water, oxygen, carbon dioxide, and many other nutrient and waste chemical substances between blood and surrounding tissues. 90007 [3] 90008 True capillaries branch mainly from metarterioles and provide exchange between cells and the circulation. The internal diameter of 8 μm forces the red blood cells to partially fold into bullet-like shapes and to go into single file in order for them to pass through.Continuous capillaries have a sealed endothelium and only allow small molecules, like water and ions to diffuse. There are those with numerous transport vesicles and tight junctions and those with few vesicles and tight junctions. Fenestrated capillaries have pores in the endothelial cells (60-80 nm in diameter) that are spanned by a diaphragm of radially oriented fibrils and allow small molecules 90007 [1] 90008 and limited amounts of protein to diffuse. Sinusoidal or discontinuous capillaries are special fenestrated capillaries that have larger openings (30-40 μm in diameter) in the endothelium to allow [[red blood cell] s and serum proteins to enter.90005 Hydrostatic pressure brings appropriate chemicals into the interstitial fluid. 90002 90003 Interstitial fluid 90004 (or 90003 tissue fluid 90004) is a solution which bathes and surrounds the cells of multicellular animals. It is the main component of the extracellular fluid, which also includes plasma and transcellular fluid. Interstitial fluid is found in the interstitial spaces, also known as the tissue spaces. Interstitial fluid consists of a water solvent containing amino acids, sugars, fatty acids, coenzymes, hormones, neurotransmitters, salts, as well as waste products from the cells.Plasma, the major component in blood, communicates freely with interstitial fluid through pores and intercellular clefts in capillary endothelium. Interstitial mixes with and becomes intercellular fluid when it flows between cells. 90005 90002 File: Cellular tight junction.svg 90005 90002 Tight junctions (TJs) are the closely associated areas of two cells whose membranes are juxtaposed forming a virtual impermeable barrier to fluid. These continuous seals around cells serve as a physical barrier to prevent solutes and water from passing freely through the paracellular space.90007 [4] 90008 TJs create an ion-selective boundary between the apical and basolateral extracellular compartments. 90007 [5] 90008 The efficiency of the junction in preventing ion passage increases exponentially with the number of strands. TJs are the most apical intercellular junctions and function as selective barriers to macromolecules and prevent diffusion of lipids and proteins between apical and basolateral membrane domains. 90007 [6] 90008 90005 TEM of negatively stained proximal convoluted tubule of Rat kidney tissue at a magnification of ~ 55,000x and 80KV with Tight junction.Note that the three dark lines of density correspond to the density of the protein complex, and the light lines in between correspond to the paracellular space. 90002 The paracellular space in the TEM image appears to be <5 nm. 90005 90002 In a gap junction the intercellular space is reduced from 25 nm to a ~ 2-4 nm wide paracellular space. 90005 90002 File: Cell junction simplified.svg 90005 Cell adhesion in desmosomes 90002 The intercellular space is very wide (about 30 nm).90005 90076 90002 This space is usually taken to be outside the plasma membrane, and occupied by fluid. The spaces occupied by extracellular fluid vary greatly in size and complexity. The stomach, which for humans may have the largest breadth between cellular layers, has a diameter in moderate distention of 24-26 cm at its maximum. 90007 [7] 90008 At the extreme a stomach diameter of over 88 cm in women and over 100 cm in men can pose a significant health risk. 90005 90002 The extracellular matrix (ECM) includes the interstitial matrix and the basement membrane.90007 [8] 90008 Interstitial matrix is ​​present between various cells (i.e., in the intercellular spaces). Gels of polysaccharides and fibrous proteins fill the interstitial space and act as a compression buffer against the stress placed on the ECM. 90007 [9] 90008 90005 90002 Hyaluronic acid in the extracellular space confers upon tissues the ability to resist compression by providing a counteracting turgor (swelling) force after absorbing a lot of water. Hyaluronic acid is thus found in abundance in the ECM of load-bearing joints.It is also a chief component of the interstitial gel. Hyaluronic acid is found on the inner surface of the cell membrane and is translocated out of the cell during biosynthesis. 90007 [10] 90008 90005 90002 The epidermal basement membrane zone (BMZ) comprises a narrow and sometimes folded interface between the basal keratinocytes and the dermis. The epidermal BMZ has small (<500 nm), regularly spaced electron dense structures which are the hemidesmosomes. Anchoring filaments traverse the lamina lucida space and appear to insert into the basal lamina.Beneath the basal lamina, loop-structured, cross-banded anchoring fibrils extend more than 300 nm beneath the basement membrane within the papillary above the reticular lamina. 90005 90002 The anterior segment is the front third of the eye that includes the structures in front of the vitreous humour: the cornea, iris, ciliary body, and lens. 90007 [11] 90008 Within the anterior segment are two fluid-filled spaces divided by the iris plane: 90005 90002 Aqueous humour fills these spaces within the anterior segment to provide nutrients to the lens and corneal endothelium, and its pressure maintains the convex shape of the cornea.90007 [12] 90008 90007 [13] 90008 90005 90002 In the Diamond-Bossert model for the production of aqueous humour, active transport occurs in the nonpigmented cilary epithelial cells inducing small osmotic pressure gradients in between the cells. A higher concentration of solutes in the proximal part of the intercellular space generates a flow of water. The concentration diminishes from the proximal part to the distal part, releasing the liquid into the posterior chamber. The primary route for aqueous humour flow is first through the posterior chamber, then the narrow space between the posterior iris and the anterior lens (contributes to small resistance), through the pupil to enter the anterior chamber.From there, the aqueous humour exits the eye through the trabecular meshwork. 90005 90002 Pus is produced from the dead and living white blood cells which travel into the intercellular spaces around the affected cells. 90005 90020 Significant sizes 90021 90002 The diameter for atoms ranges from 62 pm (He) to 520 pm (Cs). The smallest molecule is the diatomic hydrogen (H 90031 2 90032), with an overall length of roughly twice the 74 pm (0.74 Å) bond length. Molecules commonly used as building blocks for organic synthesis have a dimension of a few Å to several dozen Å.Single molecules can not usually be observed by light (as noted above), but small molecules and even the outlines of individual atoms may be traced in some circumstances by use of an atomic force microscope. Some of the largest molecules are macromolecules or supermolecules. 90005 90002 As has been learned by studying the nuclear pore complex, a 10 nm diameter corresponds to an upper mass limit of 70 kDa. 90007 [2] 90008 The majority of the non-protein molecules have a molecular mass of less than 300 Da.90007 [14] 90008 90005 90020 Acknowledgements 90021 90002 The content on this page was first contributed by: Henry A. Hoff. 90005 90002 Initial content for this page in some instances came from Wikipedia. 90005 90020 References 90021 90127 90128 ↑ 90007 1.0 90008 90007 1.1 90008 90133 Pavelka, Margit; Jürgen Roth (2005). 90134 Functional Ultrastructure: An Atlas of Tissue Biology and Pathology 90135. Springer. p. 232. 90136 90137 90128 ↑ 90007 2.0 90008 90007 2.1 90008 90133 Melchior F, Gerace L (1995)."Mechanisms of nuclear protein import". 90134 Curr Opin Cell Biol 90135. 90003 7 90004 (3): 310-8. PMID 7662359. 90136 90137 90128 ↑ 90133 Maton Anthea, Hopkins Jean, McLaughlin Charles William, Johnson Susan, Warner Maryanna Quon, LaHart David, Wright Jill D (1993). 90134 Human Biology and Health 90135. Englewood Cliffs, New Jersey: Prentice Hall. ISBN 0-13-981176-1. 90136 90137 90128 ↑ 90133 "Entrez Gene: CLDN16 claudin 16". 90136 90137 90128 ↑ 90133 Hou J, Paul DL, Goodenough DA (2005)."Paracellin-1 and the modulation of ion selectivity of tight junctions". 90134 J Cell Sci 90135. 118 (Pt 21): 5109-18. doi: 10.1242 / jcs.02631. PMID 16234325. 90136 90137 90128 ↑ 90133 Tokés AM, Kulka J, Paku S, Szik A, Páska C, Novák PK, Szilák L, Kiss A, Bögi K, Schaff Z (2005). "Claudin-1, -3 and -4 proteins and mRNA expression in benign and malignant breast lesions: a research study". 90134 Breast Cancer Res 90135. 90003 7 90004 (2): R296-305. doi: 10.1186 / bcr983. PMID 15743508. 90136 90137 90128 ↑ 90133 Gray Henry, Pick Thomas Pickering, Carter Henry Vandyke (1897).90134 Anatomy, descriptive and surgical 90135 (14 ed.). Philadelphia: Lea Brothers & Co. p. 1000. 90136 90137 90128 ↑ Kumar, Abbas, Fausto; 90134 Robbins and Cotran: Pathologic Basis of Disease 90135; Elsevier; 7th ed. 90137 90128 ↑ 90133 Alberts B, Bray D, Hopin K, Johnson A, Lewis J, Raff M, Roberts K, Walter P (2004). "Tissues and Cancer". 90134 Essential cell biology 90135. New York and London: Garland Science. ISBN 0-8153-3481-8. 90136 90137 90128 ↑ 90133 Lodish H, Berk A, Matsudaira P, Kaiser CA, Krieger M, Scott MP, Zipursky SL, Darnell J.90134 Molecular Cell Biology 90135 (5th ed.). New York: WH Freeman and Company. pp. 197-234. 90136 90137 90128 ↑ 90007 11.0 90008 90007 11.1 90008 "Departments. Anterior segment." Cantabrian Institute of Ophthalmology. 90137 90128 ↑ Miguel Coca-Prados, Ph.D. 90137 90128 ↑ Uzzle T. "The Eye, the Ear, and the Brain." 90137 90128 ↑ 90133 Goodacre R, Vaidyanathan S, Dunn WB, Harrigan GG, Kell DB (2004). "Metabolomics by numbers: acquiring and understanding global metabolite data" (PDF).90134 Trends Biotechnol 90135. 90003 22 90004 (5): 245-52. doi: 10.1016 / j.tibtech.2004.03.007. PMID 15109811. 90136 90137 90214 .90000 Lung cancer - Knowledge for medical students and physicians 90001 90002 Lung cancer is the leading cause of cancer death worldwide with around 70% of cases attributable to smoking. Lung cancer is classified into small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). SCLC is characterized by its central location, rapid tumor growth, early metastases, and association with numerous paraneoplastic syndromes. NSCLC comprises a number of cancer types, including peripheral adenocarcinoma and central squamous cell carcinoma.Symptoms such as dyspnea, cough, hemoptysis, and chest pain typically develop in advanced stages of disease. New onset cough or pneumonia constitute warning signs, particularly in smokers. Over 50% of patients have metastases at the time of diagnosis, most commonly in the brain, liver, adrenal glands, or bones. Solitary pulmonary nodules detected on chest x-ray should be compared to previous chest x-rays, if available, or evaluated in a chest CT scan. Bronchoscopy or CT-guided biopsy confirm the diagnosis.Chemotherapy is the mainstay of treatment. Surgical resection of one or more pulmonary lobes is only possible in early stages of lung cancer. Approx. 65% of patients are inoperable at the time of diagnosis because of tumor metastases or poor pulmonary function. Radiation therapy is indicated in nonsurgical candidates, as an adjunct to chemotherapy, or for palliative management of metastastic disease. Even with a multimodal approach, the 5-year survival rate is 17%. 90003 90002 90003 .