目的：探讨乳腺癌易感基因1（BRCA1）启动子CpG岛甲基化与BRCA1 mRNA表达的相关性及其意义。方法采用甲基化特异性PCR技术检测37例胃癌组织和对应癌旁组织及6例正常胃组织中BRCA1基因启动子CpG岛甲基化状态；采用逆转录PCR技术检测37例胃癌组织和对应癌旁组织及6例正常胃组织中BRCA1 mRNA 表达水平。结果胃癌组织中 BRCA1基因启动子 CpG 岛总甲基化率为48.6%（18/37），显著高于癌旁组织[5.4%（2/37）]和正常胃组织[0.0%（0/6）]，差异有统计学意义（χ2=17.541、5.021，P均<0.05）。胃癌组织中BRCA1 mRNA阳性表达率为48.6%（18/37），显著低于癌旁组织[94.6%（35/37）]和正常胃组织[100.0%（6/6）]，差异有统计学意义（χ2=19.215、5.520，P均<0.05）。BRCA1基因启动子CpG岛甲基化与BRCA1 mRNA表达成负相关（ r=-0.515，P<0.05）。结论 BRCA1基因启动子CpG岛甲基化可能是导致BRCA1 mRNA失表达的主要原因之一。%Objective To investigate the relationship between the methylation of breast cancer susceptibility gene 1(BRCA1)promoter CpG island and the expression level of BRCA1 mRNA in gastric cancer and the signifi-cance. Methods Methylation-specific PCR was used to detect the methylation of BRCA1 gene promoter CpG island in the tumor tissues and paired adjacent cancerous tissues from 37 patients gastric cancer and the 6 normal gastric tissues. reverse transcription PCR was performed to detect the expression of BRCA1 mRNA in the tumor tissues and paired ad-jacent cancerous tissues from 37 patients gastric cancer and the 6 normal gastric tissues. Results The methylation rate of the BRCA1 gene promoter CpG island in the gastric cancer tissues[48. 6%(18/37)]was higher than those in the paired adjacent tissues[5. 4%(2/37)]and the normal gastric tissues[0. 0%(0/6)](χ2 =17. 541,5. 021;P<0. 05). The expression positive rate of the BRCA1 mRNA in the gastric cancer tissues[48. 6%(18/37)]was higher than those in the paired adjacent tissues[94. 6%(35/37)]and the normal gastric tissues[100. 0%(6/6)](χ2 =19. 215,5. 520;P <0. 05 ). The methylation of BRCA1 gene promoter CpG island has a negative correlation with BRCA1 mRNA(r= -0. 515,P<0. 05). Conclusion Methylation of BRCA1 gene promoter CpG island may be one of the main reasons for the loss of BRCA1 mRNA expression.
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