A healthy breast consists of different cell types.

健康的乳房由不同類型的細胞組成。

In the nucleus of the cells, you can find the DNA.

在細胞核中，你可以找到 DNA。

Every day, the DNA of each cell is damaged thousands of times.

每天，每個細胞的 DNA 都會受到成千上萬次的破壞。

If only one strand of the DNA is damaged, this can be easily repaired. PARP proteins bind to the damage and attract other proteins that repair the damage.

如果 DNA 只有一條鏈受損，則很容易修復。PARP 蛋白與受損處結合，吸引其他蛋白質修復受損處。

When damaged DNA duplicates before the damage is repaired, a double-strand break can arise.

當受損 DNA 在修復前複製時，就會出現雙鏈斷裂。

In a healthy cell, this more severe damage can be repaired with the help of homologous recombination.

在健康細胞中，這種更嚴重的損傷可以藉助同源重組進行修復。

BRCA1 protein binds the loose ends of the DNA and starts to unravel the DNA strands.

BRCA1 蛋白與 DNA 的鬆散末端結合，開始解開 DNA 鏈。

Using the undamaged DNA strand as a template, the damage is then repaired.

以未受損的 DNA 鏈為模板，修復損傷。

Finally, the two strands are separated, leaving both DNA strands error-free. In patients with hereditary breast cancer, the BRCA1 mechanism does not work.

最後，兩條鏈分離，使兩條 DNA 鏈都不出錯。在遺傳性乳腺癌患者中，BRCA1 機制不起作用。

When a double-strand break arises in the cells of these patients, the DNA cannot be repaired.

當這些患者的細胞出現雙鏈斷裂時，DNA 無法修復。

The persisting damage can cause cells to die, but it can also transform a cell into a cancer cell.

持續的損傷會導致細胞死亡，但也會將細胞轉化為癌細胞。

This cancer cell is the start of a tumour in which all cells have the same defect. In this patient-specific treatment, an inhibitor of PARP is being used.

這種癌細胞是腫瘤的開端，其中所有細胞都有相同的缺陷。在這種針對患者的治療中，使用的是 PARP 抑制劑。

The inhibitor reaches the tumour via the bloodstream and inactivates the PARP proteins.

抑制劑通過血液到達腫瘤，使 PARP 蛋白失活。

When a single-strand break arises in the DNA of the tumour cell, it can no longer be repaired.

當腫瘤細胞的 DNA 出現單鏈斷裂時，就無法再進行修復。

The persisting single-strand break can transform into a double-strand break.

持續存在的單鏈斷裂可轉化為雙鏈斷裂。

Because of the hereditary defect in the tumour cells, the BRCA1 protein cannot repair this damage, causing the tumour cells to die. In the surrounding healthy cells, the repair mechanism of single-strand breaks is also inactivated by the PARP inhibitor.

由於腫瘤細胞的遺傳缺陷，BRCA1 蛋白無法修復這種損傷，導致腫瘤細胞死亡。在周圍的健康細胞中，PARP 抑制劑也會使單鏈斷裂的修復機制失活。

These cells, however, still have active BRCA1 proteins, which repair the double-strand breaks and allow the cells to survive.

但是，這些細胞中仍有活性 BRCA1 蛋白，它們能修復雙鏈斷裂，使細胞存活下來。

As soon as the PARP inhibitor is removed after treatment, the repair of single-strand breaks is reactivated.

治療後一旦移除 PARP 抑制劑，單鏈斷裂的修復就會重新激活。

By that time, all tumour cells have already been killed. Towards a new treatment for breast cancer.

此時，所有腫瘤細胞都已被殺死。邁向乳腺癌的新療法。