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目的:探讨癌高甲基化1(hypermethylated in cancer 1,HIC-1)基因在乳腺癌组织中的表达,以及恢复HIC-1基因表达对乳腺癌细胞增殖活力和凋亡的影响。方法:应用免疫组化方法测定乳腺癌组织芯片中80例癌组织的HIC-1蛋白表达,并分析其与临床病理的关系。应用甲基化特异性PCR法检测乳腺癌MDA-MB-231细胞中HIC-1基因启动子区域甲基化与基因表达的关系,5-氮杂-2′-脱氧胞苷(5-aza-2′-deoxycytidine,5-aza-CdR)抑制甲基化后细胞HIC-1的表达水平变化。应用CCK-8方法和流式细胞仪测定恢复细胞HIC-1表达对MDA-MB-231细胞增殖和凋亡的影响。结果:正常乳腺上皮组织HIC-1免疫组化染色呈强阳性,平均染色积分9.00±0,乳腺癌组织HIC-1染色明显降低,平均染色积分为4.58±1.22(P<0.001)。HIC-1的蛋白表达与病人年龄、发生部位以及是否出现淋巴结转移无关,但与肿瘤的组织学类型相关(P<0.05)。MDA-MB-231细胞HIC-1基因启动子区域呈完全甲基化,用5μM的5-aza-CdR处理后可抑制HIC-1基因启动子甲基化、恢复HIC-1表达,并呈现浓度依赖性。恢复HIC-1基因表达抑制MDA-MB-231细胞增殖活性,促进MDA-MB-231细胞凋亡(P<0.05)。结论:乳腺癌组织HIC蛋白表达和癌细胞HIC-1基因表达明显降低,去甲基化药物可恢复肿瘤细胞内HIC-1基因表达,从而达到抑制肿瘤细胞增殖并促进细胞凋亡的目的。
OBJECTIVE: To investigate the expression of hypermethylated in cancer 1 (HIC-1) gene in breast cancer and the effect of HIC-1 gene expression on the proliferation and apoptosis of breast cancer cells. Methods: Immunohistochemical method was used to detect the expression of HIC-1 protein in 80 cases of breast cancer tissue microarray. The relationship between the expression of HIC-1 and clinical pathology was analyzed. The methylation-specific PCR method was used to detect the relationship between methylation and gene expression of HIC-1 promoter in breast cancer MDA-MB-231 cells. The relationship between 5-aza- 2’-deoxycytidine, 5-aza-CdR) inhibited the expression of HIC-1 in the cells. The effects of HIC-1 expression on the proliferation and apoptosis of MDA-MB-231 cells were determined by CCK-8 assay and flow cytometry. Results: Immunohistochemical staining of HIC-1 in normal mammary epithelium showed a strong positive staining with an average staining score of 9.00 ± 0. HIC-1 staining in breast cancer tissues was significantly decreased with an average staining score of 4.58 ± 1.22 (P <0.001). HIC-1 protein expression and age, location and lymph node metastasis has nothing to do, but with the histological type of tumor (P <0.05). The promoter region of HIC-1 gene in MDA-MB-231 cells was completely methylated. Treatment with 5μM 5-aza-CdR inhibited the promoter methylation of HIC-1 gene and restored the expression of HIC-1, Dependency. Restoration of HIC-1 gene expression inhibited the proliferation of MDA-MB-231 cells and promoted the apoptosis of MDA-MB-231 cells (P <0.05). CONCLUSION: The expression of HIC protein and HIC-1 gene in breast cancer tissues are significantly decreased. Demethylation drugs can restore the expression of HIC-1 gene in tumor cells and thus inhibit tumor cell proliferation and promote apoptosis.