The two-hit hypothesis suggests that a second mutation is necessary for cancer development in cells with a defective tumor-suppressor gene, such as BRCA1. However, a study now shows that the loss of just one Brca1 allele in mice can pre-program cells for cancer-promoting changes, indicating cancer may progress earlier than previously thought.

中文翻译：

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Brca1 丢失的表观遗传瘢痕指向乳腺癌细胞起源


两次命中假说表明，在具有肿瘤抑制基因缺陷的细胞（如 BRCA1）中，癌症发展需要第二次突变。然而，现在的一项研究表明，小鼠中仅丢失一个 Brca1 等位基因就可以对细胞进行预编程以促进癌症的变化，这表明癌症可能比以前认为的更早进展。