5分鐘前，你的身體剛剛殺死了一個癌細胞：英語精讀講義

Somewhere in your body,

在你身體的某個角落，

your immune system just quietly killed one of your own cells,

你的免疫系統剛剛悄無聲息地殺死了一個你自身的細胞，

stopping it from becoming cancer

阻止了它癌變，

and saving your life.

從而拯救了你的生命。

It does that all the time.

它一直在做著這樣的工作。

The vast majority of cancer cells you develop will be killed without you ever noticing, 文法

你體內產生的絕大多數癌細胞都會在你毫無察覺的情況下被消滅，

which is an incredibly hard job because of what cancer cells are.

這是一項極其艱難的任務，因為癌細胞有著特殊的本質。

Parts of yourself that start to behave as individuals,

它們是你身體的一部分，卻開始像獨立的個體一樣運作，

even if it hurts you.

哪怕這會傷害到你。

What is cancer and how does your body kill it all the time?

什麼是癌症？你的身體又是如何無時無刻不在消滅它的？

Cancer is when corrupted cells multiply uncontrollably.

癌症是受損細胞失控繁殖的結果。

It can emerge from basically every type of cell in your body,

它基本上可以從你體內的任何一種細胞中產生，

so there's not just a single type of cancer, 文法

所以癌症不僅僅只有一種，

but hundreds.

而是有數百種。

Some grow slowly,

有些生長緩慢，

others are aggressive,

有些則具有很強的侵襲性，

some can be treated effectively,

有些可以被有效治療，

others are deadly.

而另一些則是致命的。

In a sense,

從某種意義上說，

a cell that becomes cancer turns into something ancient and something new. 片語動詞

一個變成癌的細胞既退化成了某種古老的事物，又變成了某種新的東西。

Over billions of years,

在數十億年的時間裡，

evolution has molded cells to survive and thrive in a hostile environment, 片語搭配

演化塑造了細胞，讓它們在惡劣的環境中生存繁衍，

fighting for space and resources,

爭奪空間和資源，

until a new and exciting way of life emerged,

直到一種全新且令人興奮的生活方式出現——

cooperation.

合作。

A division of labor that allowed cells to specialize and become more successful together. 用詞

這種分工讓細胞能夠專業化，並共同取得更大的成功。

But cooperation requires sacrifices.

但是合作需要犧牲。

For a multicellular being to stay healthy,

為了讓多細胞生物保持健康，

the well-being of the collective has to matter more than the survival of the individual cell. 文法

集體的福祉必須凌駕於單個細胞的生存之上。

Cancer cells stop being part of the collective and become individuals again.

癌細胞不再作為集體的一部分，而是再次成為了個體。

Your body can handle a few rogue cells, 用詞

你的身體可以處理少數幾個叛變的細胞，

but some cancer cells divide again and again,

但有些癌細胞會一遍又一遍地分裂，

becoming a sort of new organism within you,

在你體內變成一種類似新生物的存在，

taking resources you need to survive,

掠奪你生存所需的資源，

competing for the space you inhabit,

爭奪你所居住的空間，

destroying the organs they were part of in the process.

並在這個過程中摧毀它們曾經所屬的器官。

Despite the harm they cause,

儘管它們會造成傷害，

cancer cells are not evil.

癌細胞卻並不邪惡。

They don't want to hurt you,

它們不想傷害你，

they don't want anything.

它們什麼也不想要。

Cells are protein robots that just follow their programming,

細胞只是遵循其程序的蛋白質機器人，

which unfortunately has been corrupted.

只是不幸的是，它的程序被破壞了。

The soul of the cell.

細胞的靈魂。

In a nutshell, 慣用語

簡而言之，

your cells have a nucleus filled with DNA.

你的細胞裡有一個充滿DNA的細胞核。

It consists of genes,

它由基因組成，

instructions for how to build proteins and when to make each one.

基因就是關於如何製造蛋白質以及何時製造每種蛋白質的指令。

These building instructions are copied and transferred to ribosomes,

這些製造指令被複製並轉移到核糖體，

where they're used to make proteins.

在那裡被用來製造蛋白質。

What kind of proteins your cells make determine what they can do.

你的細胞製造什麼樣的蛋白質決定了它們能做什麼。

The important thing here is that a corrupt gene means you get a corrupt protein,

這裡重要的是，基因受損意味著你會得到受損的蛋白質，

which will get important later.

這一點稍後會很關鍵。

Your DNA gets a tiny bit corrupted,

你的DNA會受到極微小的破壞，

it mutates tens of thousands of times each day.

它每天變異數萬次。

Most of the time without any special cause,

大多數時候沒有任何特殊原因，

just by being alive.

僅僅是因為你活著。

Almost all of these mutations are fixed very quickly or are not problematic.

幾乎所有這些突變都會被非常快速地修復，或者根本不會造成問題。

Still, over time as your cells make copies of themselves,

然而，隨著時間的推移，當你的細胞進行自我複製時，

damage is accumulating.

損傷就在不斷累積。

Imagine having to make copies from copies from copies for decades. 表達脈絡

想像一下，幾十年裡不得不拿著影印本再影印，再拿影印本影印。

Maybe one day a hair got on the scanner or a corner got frayed.

也許有一天，掃描器上掉了一根頭髮，或者角落被磨損了。

Each new mistake becomes part of the new copies and all the copies that follow.

每一個新錯誤都會成為新影印本的一部分，並體現在所有隨後的影印本中。

You can increase DNA damage by doing things like smoking,

你可以透過吸菸、

drinking alcohol, by being obese,

飲酒、肥胖、

breathing in asbestos,

吸入石棉、

by not using sunscreen,

不塗防曬乳、

or contracting a virus like HPV. 文化背景

或者感染像HPV這樣的病毒來增加DNA損傷。

But the simplest way to damage DNA and get cancer

但是損傷DNA並罹患癌症的最簡單方法，

is to be alive long enough.

就是活得足夠久。

For many cancer cases,

對於許多癌症病例來說，

there is no cause other than bad luck.

除了運氣不好，沒有任何其他原因。

The damage that leads to cancer.

導致癌症的損傷。

We are simplifying,

我們把事情簡化一下，

but roughly there are three categories of genes that need to be corrupted so cancer can arise.

大致有三類基因需要被破壞才能引發癌症。

The first key mutation is in the appropriately named tumor suppressor genes or TSGs. 文化背景

第一個關鍵突變發生在名副其實的腫瘤抑制基因（TSG）中。

These genes are a bunch of things.

這些基因包含很多種類。

For one, they produce control mechanisms that continuously scan your DNA for mistakes and copying errors 表達脈絡

首先，它們產生控制機制，不斷掃描你的DNA中的錯誤和複製失誤，

and fix them right away.

並立即修復它們。

And then they keep normal cells from multiplying recklessly. 文法

然後，它們會阻止正常細胞不計後果地繁殖。

If TSGs become damaged,

如果腫瘤抑制基因（TSG）受損，

your cells basically forget how to repair themselves

你的細胞基本上就會忘記如何自我修復，

and can reproduce unchecked. 用詞

並可能不受控制地繁殖。

The second crucial mutation can happen in your oncogenes. 文化背景

第二個關鍵突變可能發生在你的致癌基因中。

When oncogenes are turned on,

當致癌基因被開啟時，

the cell is told to multiply rapidly.

細胞會被指令快速繁殖。

They were super active when you were inside your mother's womb.

當你在母親的子宮裡時，它們超級活躍。

To turn a single original cell into trillions in months,

為了在幾個月內把一個原始細胞變成數以萬億計的細胞，

it needs to divide and grow rapidly.

它需要快速分裂和生長。

These rapid growth genes are turned off when there's enough of you. 片語動詞

當你長得足夠大時，這些快速生長的基因就會被關閉。

When your oncogenes get corrupted,

當你的致癌基因受損時，

they basically turn on again.

它們基本上就會再次開啟。

The third crucial mutation is in your cells' suicide switch. 慣用語

第三個關鍵突變發生在細胞的「自殺開關」上。

Most cells are constantly recycled and refreshed.

大多數細胞都在不斷被回收和更新。

When cells amass too much damage,

當細胞累積了過多的損傷時，

they usually notice and special genes trigger a controlled suicide called apoptosis. 文化背景

它們通常能察覺到，特殊基因會觸發一種稱為細胞凋亡的受控自殺。

If the genes that control this process get damaged,

如果控制這個過程的基因受損，

cells are free to live on despite being dangerously corrupted. 講解

細胞就會無視危險的損壞而繼續存活。

So, if a cell becomes unable to fix the mistakes in its genetic code,

所以，如果一個細胞變得無法修復其遺傳密碼中的錯誤，

loses the ability to destroy itself when it notices the damage,

在察覺到損傷時失去了自我毀滅的能力，

and begins to grow rapidly without restraint,

並且開始不受約束地快速生長，

it turns into a young cancer cell.

它就變成了一個初期的癌細胞。

These cells have to be killed as quickly as possible.

這些細胞必須儘快被殺死。

While they are bad at this stage,

雖然它們在這個階段是有害的，

they are still pretty weak and easy to kill.

但它們仍然相當虛弱，很容易被殺死。

But if they continue to mutate and increase in number, 片語搭配

但如果它們繼續變異並增加數量，

they can learn to avoid your defenses and become a real threat.

它們就能學會躲避你的防禦，成為真正的威脅。

At any moment of your life,

在你生命的任何時刻，

your immune system is hunting these cells.

你的免疫系統都在搜捕這些細胞。

But how do you identify and kill corrupted cells that seem indistinguishable from healthy ones?

但是，你如何識別並殺死那些看起來與健康細胞無法區分的受損細胞呢？

How to find cancer?

如何尋找癌症？

Well, here we come back to the proteins your cells produce and the story they tell. 片語動詞

好吧，這又要回到你的細胞所製造的蛋白質以及它們所講述的故事上。

So, if for example, your oncogenes switch back on,

所以，舉例來說，如果你的致癌基因重新開啟，

they make oncogene proteins.

它們就會製造致癌基因蛋白質。

Your immune system knows that they should not be present if you're an adult.

你的免疫系統知道，如果你是成年人，它們就不應該出現。

So, to know which cells are corrupt and which are healthy,

因此，要知道哪些細胞受損，哪些是健康的，

your immune system needs to know what proteins they're making inside.

你的免疫系統需要知道它們內部正在製造什麼蛋白質。

To solve this,

為了解決這個問題，

evolution came up with MHC class 1 molecules, 講解

演化出了一套MHC-I類分子系統，

a sort of display window that makes cells transparent. 慣用語

這是一種讓細胞變得透明的展示櫥窗。

Cells constantly take little samples of the proteins they make

細胞不斷地提取它們製造的蛋白質的小樣本，

and put them into thousands of these MHC molecules

並將它們放入數以千計的這些MHC分子中，

to showcase what they're doing.

以展示它們正在做什麼。

The selection is constantly refreshed,

展示的樣本會不斷更新，

always giving an up-to-date picture. 片語搭配

始終提供最新的情況。

There's a whole library of proteins that are highly dangerous

存在著一個極其危險的蛋白質特徵庫，

and should not be made by healthy cells,

健康細胞不應該製造這些蛋白質，

and your immune system has them all on file. 慣用語

而你的免疫系統已經將它們全部建檔。

It has billions of specialized cells called T cells 文化背景

它擁有數十億被稱為T細胞的特化細胞，

made to recognize specific proteins.

專門用來識別特定的蛋白質。

If a T cell sees a forbidden protein in an MHC display window,

如果T細胞在MHC展示櫥窗中看到了被禁止的蛋白質，

it knows that the cell is corrupted and kills it immediately.

它就知道該細胞已受損，並立即將其殺死。

But there's a flaw in this system.

但這個系統存在一個缺陷。

What if a cancer cell mutates and finds a way to circumvent this process? 片語搭配

如果癌細胞發生突變，找到繞過這個過程的方法怎麼辦？

All it needs to do is to stop making MHC class 1 molecules 文法

它需要做的就是停止製造MHC-I類分子，

and boom, it's invisible.

然後砰！它就隱身了。

Without display windows,

沒有展示櫥窗，

the immune system is blind and can't identify cancer anymore. 慣用語

免疫系統就成了瞎子，再也無法識別癌症了。

Fortunately,

幸運的是，

evolution found an ingenious solution,

演化找到了一個巧妙的解決方案：

the natural killer cell, 文化背景

自然殺手細胞，

a judge, jury, and executioner. 慣用語

它是法官、陪審團和劊子手。

The killer.

殺手。

At this very second,

就在這一秒，

hundreds of millions of natural killer cells are patrolling your body,

數以億計的自然殺手細胞正在你的體內巡邏，

looking for cells that have already turned into cancer

尋找那些已經變成癌症

or are corrupted by a virus.

或被病毒破壞的細胞。

Natural killer cells go from cell to cell

自然殺手細胞在細胞間遊走，

to check for one thing.

只檢查一件事。

Does a cell have MHC class 1 molecules?

這個細胞有MHC-I類分子嗎？

Does it have a display window

它有展示櫥窗嗎？

and is it doing its duty of showing off what's going on inside itself? 講解

它是否履行了展示其內部情況的職責？

This is so amazing because it covers all of your bases. 慣用語

這真是太神奇了，因為它做到了萬無一失。

While T cells look for the presence of the unexpected, 表達脈絡

T細胞尋找的是不應存在之物的出現，

something that should not be here,

即本不該在這裡的東西；

natural killer cells look for the absence of the expected,

而自然殺手細胞尋找的是應有之物的缺失，

the absence of something that should be here.

即本應在這裡的東西卻不在了。

The logic is,

邏輯是，

if a cell does not have display windows,

如果一個細胞沒有展示櫥窗，

it wants to hide something.

它就想隱藏什麼。

And a cell that hides something must be killed.

而隱藏東西的細胞必須被殺死。

What makes the natural killer cell even more metal is that it's always in murder mode. 講解

讓自然殺手細胞更加硬核的是，它始終處於殺戮模式。

It patrols your body,

它在你體內巡邏，

checking cell after cell with the intention of killing it. 片語搭配

帶著殺死的意圖檢查一個又一個細胞。

Your healthy cells have to convince it that they should not die today.

你健康的細胞必須說服它，它們今天不該死。

And a way to do that is to have MHC class 1 molecules. 文法

做到這一點的方法就是擁有MHC-I類分子。

So, in summary,

所以總的來說，

almost all young cancer cells you will ever develop in your life

你一生中可能產生的所有初期癌細胞，幾乎

will be killed by your immune system.

都會被你的免疫系統殺死。

Okay,

好吧，

but if your body is this prepared, 用詞

但如果你的身體準備得如此充分，

why do we still get cancer?

為什麼我們還是會得癌症呢？

Well,

這是因為，

sometimes cancer cells mutate more and get much better at fighting back. 片語動詞

有時癌細胞會發生更多的突變，反擊能力大大增強。

Cancer is a story of an arms race, 慣用語

癌症是一個軍備競賽的故事，

an arms race that we will win eventually,

一場我們最終會贏得的軍備競賽，

maybe with the help of natural killer cells.

也許是在自然殺手細胞的幫助下。

Right now,

目前，

a number of therapies are beginning to show amazing promise, 片語搭配

許多療法開始展現出驚人的前景，

from cancer-fighting vaccines to engineered T cells 文法

從抗癌疫苗到基因工程T細胞，

and even natural killer cells.

甚至自然殺手細胞療法。

We'll look at these therapies in future videos.

我們將在以後的影片中介紹這些療法。

So,

所以，

the war is not won yet,

這場戰爭還沒有勝利，

but we are on to cancer 慣用語

但我們已經摸清了癌症的底細，

and eventually it will be eliminated once and for all. 慣用語

最終它將被一勞永逸地消滅。

Maybe sooner than we think.

也許比我們想像的還要快。

This video was made possible in part by direct viewer support 表達脈絡

本影片的製作部分得益於觀眾的直接支持，

and in part through a grant by Gates Ventures.

部分得益於Gates Ventures的贊助。

Thanks a lot for their support

非常感謝他們的支持，

and stay tuned for part two. 慣用語

請繼續關注第二部分。

Please check out our source document for more background and in-depth information. 講解

請查看我們的參考文檔以獲取更多背景資訊和深入資料。