The cancer gene we all have - Michael Windelspecht

潛藏在人人體內的「癌症基因」——麥可・溫德斯特

譯者: Denise Tso 審譯者: Regina Chu

Cancer is like a car crash.

癌症就像一場車禍

Your body typically regulates

通常，你的身體可以調節

the speed at which your cells divide,

體內細胞分裂的速度

but sometimes, cancer cuts the brake lines,

但是有時候 癌症把煞車油管給切斷了

and your cells divide too quickly,

讓你的細胞分裂太快

accumulating mutations that cause them

積累的變異

to veer away from their original function,

使細胞偏離了原本功能

form dangerous tumors,

從而形成危險的腫瘤

and land you in the hospital.

把你送進醫院

Cancer is basically an inability of the body

基本上，癌症就是身體

to control the speed at which cells divide.

無法控制細胞分裂速度的體現

When cells divide too quickly,

當細胞分裂得太快

they can often accumulate mutations

變異便有可能產生並積聚在體內

that cause them to ignore their original function in the body,

促使細胞忽視它們在身體原有的作用

forming tumors.

最後形成腫瘤

In turn, these tumors may interfere

接下來，這些腫瘤可以干擾到

with the natural processes of the body,

體內的自然活動

such as digestion and respiration,

譬如消化和呼吸

potentially leading to death.

導致死亡

Typically, your body has a number of genetic mechanisms

一般情況下 你的身體有幾組基因機制

to control how fast your cells divide.

以控制細胞分裂的速度

One of these genes is BRCA1,

其中一種基因就是 BRCA1

which stands for breast cancer susceptibility gene 1.

全名是「乳腺癌易感基因 1 號」

BRCA1 belongs to a class of genes

BRCA1 屬於

called tumor suppressor genes.

腫瘤抑制基因的一種

Tumor suppressor genes are involved

這種基因負責

in regulating how fast a cell divides.

管制細胞分裂的速度

Normally, cell division follows an orderly process

通常，細胞分裂是依循一個叫

called the cell cycle,

細胞週期的有序過程

which is basically the life cycle of a cell.

也就是細胞的生命週期

Within the cell cycle

在細胞週期內

is a series of checkpoints,

有一系列「關卡」

where proteins, such as the one produced by BRCA1,

關卡裏面的多種蛋白質 如 BRCA1 產生的其中一種

regulate how fast the cell may proceed.

負責調節細胞在過程中 進展的速度

How does it do this?

它是如何做到這點的呢？

BRCA1 helps repair some forms of mutation in your DNA.

BRCA1 幫助修復 DNA 裏 某些變異類型

If your DNA is damaged,

如果你的 DNA 遭受損壞

BRCA1 keeps the cell from dividing

BRCA1 會暫時阻止細胞分裂

until the mutation is repaired.

直到該變異被修復

You have two copies of the BRCA1 gene

人體的每一個細胞裏

in every cell of your body.

都有兩份 BRCA1 的副本

One copy you inherited from Mom,

一份遺傳自母親

the other from Dad.

一份遺傳自父親

This redundancy is a good a thing

這樣的重複是件好事

because you only need one functioning BRCA1 gene in a cell

因為雖然一個細胞裏 你只需要一個 BRCA1 基因在運作

to regulate the cell cycle.

以管制細胞週期

But it's important to note

但有一點非常重要

that while these copies have a similar function

即使這兩個 BRCA1 副本有類似作用

they're not necessarily the same.

它們也不一定一模一樣

In fact, there are hundreds of variations,

事實上，BRCA1 有著幾百種變化

or alleles, of BRCA1.

或者叫等位基因

Some regulate the cell cycle more effectively than others.

一些在規管細胞週期方面 更有效率

In other words,

換句話來說

some people are born

有些人的調節修復機制

with better regulating and repair mechanisms than others.

生來就比別人好

And in some cases, mutations may render BRCA1 ineffective.

但在某些情況下 變異也可能導致 BRCA1 喪失功能

When this happens,

當這種情況發生時

DNA 損壞的細胞就能夠分裂

cells with damaged DNA are allowed to divide.

As they divide,

一旦進行分裂

these cells may accumulate additional mutations.

這些細胞就會積累更多附加變異

這些變異可能讓細胞

These mutations may cause the cell

to become less specialized

原有能力減退

and stop performing its original function in the tissue.

從而停止在人體組織正常運作

If this occurs, then there's a greater chance

如果這種情況發生 那就有極大可能

they'll develop into cancer cells.

出現癌細胞

While we all have the gene, such as BRCA1, that can cause cancer,

我們有些基因，譬如 BRCA1 的確能發展成癌症

it's only when these genes fail at their function

但是癌症只會在

that problems develop.

這些基因失去原有功能時出現

Having an ineffective or mutated version of BRCA1

帶有失效或變異的 BRCA1

can increase your susceptibility to cancer,

會增加罹患癌症風險的機會

much like driving with bad brakes

就跟因開一輛剎車制失靈的車

increases the risk of an accident.

而增加車禍風險的機會一樣