乳腺癌易感基因研究进展

The progress of studying on breast cancer susceptibility genes

Ｂｒｃａ１和Ｂｒｃａ２是乳腺癌易感基因，在家族性乳腺癌患者中的突变是可以遗传的，在散发性乳腺癌患者中有杂合性丢失（ＬＯＨ），而且表达水平下降。体外实验证明，Ｂｒｃａ１能抑制乳腺癌和卵巢癌细胞的增殖。Ｂｒｃａ１和Ｂｒｃａ２基因分别定位于１７ｑ１２－２１和１３ｑ１２－１３，编码序列分别为５７１１ｂｐ和１０９８７ｂｐ，其表达有一定的组织特异性。ＢＲＣＡ１和ＢＲＣＡ２蛋白分别由１８６３个氨基酸和３４１８个氨基酸组成，这两个蛋白都具有Ｇｒａｎｉｎ蛋白的某些特征。它们的功能目前还不是很清楚，但有证据表明这两个基因为生长发育所必须，并参与细胞增殖分化和ＤＮＡ损伤修复等生命活动。

Brcal and Brca2 genes are breast cancer susceptibility genes. Their germline mutations in familial breast cancer patients can be inhereted. In sporadic breast cancer patients these two genes may display loss of heterozygosity(LOH). And their experessions ae decreased. In vitro Brcal inhibits growth of breast and ovarian cancer cells. Brcal is localized to chromosome 17q12 21 and its encoding sequence has 5,711bp. Brca2 is localized to chromosome 13q12 13, its encoding sequence has 10,987bp. These two genes' expressions are tissue specific. Brcal and Brca2 protein have 1,863 and 3,418 amino acids respectively. Their functions are still not known, but it is proved that these two genes are required in development, and involved in cellular proliferation, differentiation and repair of DNA double strand breaks.