Your body typically regulates the speed at which your cells divide, but sometimes, cancer cuts the brake lines,

あなたの体は普通細胞が分裂する速さを調節しています

and your cells divide too quickly, accumulating mutations that cause them to veer away from their original function, form dangerous tumors, and land you in the hospital.

しかし、時々ガンがブレーキケーブルを切断してしまいます

Cancer is basically an inability of the body to control the speed at which cells divide.

すると、細胞の分裂は速くなりすぎ、突然変異が溜まって正常な機能を営めなくなります

When cells divide too quickly, they can often accumulate mutations that cause them to ignore their original function in the body, forming tumors.

そして危険な腫瘍を作り、病院を訪れることとなってしまいます

In turn, these tumors may interfere with the natural processes of the body, such as digestion and respiration, potentially leading to death.

ガンは自分の体が細胞の分裂する速さを コントロールできなくなった状態です

Typically, your body has a number of genetic mechanisms to control how fast your cells divide.

細胞があまりに速く分裂すると

One of these genes is BRCA1, which stands for breast cancer susceptibility gene 1.

突然変異が溜まりやすくなり

BRCA1 belongs to a class of genes called tumor suppressor genes.

それが正常な体の機能を無視するようになり腫瘍を作ります

Tumor suppressor genes are involved in regulating how fast a cell divides.

そして腫瘍は消化や呼吸といった正常な体の働きを妨げて

Normally, cell division follows an orderly process called the cell cycle, which is basically the life cycle of a cell.

死に追いやるかもしれないのです

Within the cell cycle is a series of checkpoints, where proteins, such as the one produced by BRCA1, regulate how fast the cell may proceed.

体には細胞の分裂速度をコントロールする

How does it do this?

遺伝子的仕組みがあり

BRCA1 helps repair some forms of mutation in your DNA.

その一つが「乳ガン抑制遺伝子」の省略で BRCA1と呼ばれるものです

If your DNA is damaged, BRCA1 keeps the cell from dividing until the mutation is repaired.

BRCA1はガン抑制遺伝子

You have two copies of the BRCA1 gene in every cell of your body.

と呼ばれる遺伝子の一つで

One copy you inherited from Mom, the other from Dad.

細胞分裂速度を調整しています

This redundancy is a good thing because you only need one functioning BRCA1 gene in a cell to regulate the cell cycle.

細胞分裂速度を調整しています

But it's important to note that while these copies have a similar function they're not necessarily the same.

細胞分裂速度を調整しています

In fact, there are hundreds of variations, or alleles, of BRCA1.

通常、細胞分裂は

Some regulate the cell cycle more effectively than others.

細胞周期と呼ばれる

In other words, some people are born with better regulating and repair mechanisms than others.

規則正しいものです

And in some cases, mutations may render BRCA1 ineffective.

細胞周期の過程では

When this happens, cells with damaged DNA are allowed to divide.

いくつかのチェックポイントがあって

As they divide, these cells may accumulate additional mutations.

BRCA1遺伝子から 作られるようなタンパク質が

These mutations may cause the cell to become less specialized and stop performing its original function in the tissue.

細胞周期速度を調節しています

If this occurs, then there's a greater chance they'll develop into cancer cells.

どのようにするのでしょう

While we all have the gene, such as BRCA1, that can cause cancer, it's only when these genes fail at their function that problems develop.

BCRA1はDNAが損傷を受けたとき、それを修復します

Having an ineffective or mutated version of BRCA1 can increase your susceptibility to cancer, much like driving with bad brakes increases the risk of an accident.

つまり、