Genetic and epigenetic silencing of the beclin 1 gene in sporadic breast tumors.
Genetic and epigenetic silencing of the beclin 1 gene in sporadic breast tumors.
复制标题
DOI：
10.1186/1471-2407-10-98
复制
发表时间：
2010-03-16
期刊：
影响因子：
3.8
通讯作者：
Liu X
中科院分区：
文献类型：
--
作者：
Li Z;Chen B;Wu Y;Jin F;Xia Y;Liu X
Beclin 1是人类细胞中一种重要的自噬相关蛋白，参与细胞死亡和细胞存活。Beclin 1定位于人类染色体17 q21。在正常乳腺上皮细胞中广泛表达。乳腺肿瘤中常出现beclin 1基因单等位基因缺失导致的表达下调，但beclin 1是否存在其他调控机制尚待进一步研究。我们研究了beclin 1在乳腺肿瘤中的表达，并探讨其表达的可能调控机制。收集20对散发性乳腺浸润性导管癌（IDC）患者的肿瘤和邻近正常组织。实时荧光定量RT-PCR检测Beclin 1 mRNA的表达。采用实时荧光定量PCR和微卫星技术检测基因杂合性缺失（洛）。免疫组化检测Beclin 1、p53、BRCA 1、BRCA 2蛋白表达。用MethylPrimer程序鉴定了beclin 1基因5'端的CpG岛。亚硫酸氢钠测序用于检查每个CpG岛的甲基化状态。70%的乳腺肿瘤中Beclin 1 mRNA表达降低，且Beclin 1蛋白表达水平与Beclin 1 mRNA表达水平相关。Beclin 1 mRNA在BRCA 1阳性的乳腺癌组织中的表达明显高于BRCA 1阴性的乳腺癌组织。在45%以上的乳腺肿瘤中检测到杂合性丢失，并且从beclin 1基因的5'端到内含子2发现密集的CpG岛簇。甲基化分析显示，在表达降低的肿瘤中，beclin 1的启动子和内含子2发生异常甲基化。提示乳腺癌组织中Beclin 1基因表达降低可能与洛缺失和DNA甲基化异常有关。这些发现为乳腺癌中beclin 1的调控机制提供了新的线索。
Beclin 1, an important autophagy-related protein in human cells, is involved in cell death and cell survival. Beclin 1 mapped to human chromosome 17q21. It is widely expressed in normal mammary epithelial cells. Although down-regulated expression with mono-allelic deletions of beclin 1 gene was frequently observed in breast tumors, whether there was other regulatory mechanism of beclin 1 was to be investigated. We studied the expression of beclin 1 and explored the possible regulatory mechanisms on its expression in breast tumors. 20 pairs of tumors and adjacent normal tissues from patients with sporadic breast invasive ductal cancer (IDCs) were collected. The mRNA expression of beclin 1 was detected by real-time quantitative RT-PCR. Loss of heterozygosity (LOH) was determined by real-time quantitative PCR and microsatellite methods. The protein expression of beclin 1, p53, BRCA1 and BRCA2 was assessed by immunohistochemistry. CpG islands in 5' genomic region of beclin 1 gene were identified using MethylPrimer Program. Sodium bisulfite sequencing was used in examining the methylation status of each CpG island. Decreased beclin 1 mRNA expression was detected in 70% of the breast tumors, and the protein levels were co-related to the mRNA levels. Expression of beclin 1 mRNA was demonstrated to be much higher in the BRCA1 positive tumors than that in the BRCA1 negative ones. Loss of heterozygosity was detected in more than 45% of the breast tumors, and a dense cluster of CpG islands was found from the 5' end to the intron 2 of the beclin 1 gene. Methylation analysis showed that the promoter and the intron 2 of beclin 1 were aberrantly methylated in the tumors with decreased expression. These data indicated that LOH and aberrant DNA methylation might be the possible reasons of the decreased expression of beclin 1 in the breast tumors. The findings here shed some new light on the regulatory mechanisms of beclin 1 in breast cancer.
登录
查看更多内容
DOI：
10.1073/pnas.93.18.9821
发表时间：
1996-09-03
影响因子：
11.1
作者：
Herman, JG;Graff, JR;Baylin, SB
通讯作者：
Baylin, SB
影响因子：
10.3
作者：
Lakhani, SR;Jacquemier, J;Easton, DF
通讯作者：
Easton, DF
影响因子：
3.7
作者：
Furuya, D;Tsuji, N;Watanabe, N
通讯作者：
Watanabe, N
影响因子：
11.2
作者：
Douglas, DB;Akiyama, Y;Baylin, SB
通讯作者：
Baylin, SB
影响因子：
5.4
作者：
Liang, XH;Kleeman, LK;Levine, B
通讯作者：
Levine, B