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背景与目的:对结晶型硫化镍(Nickelsulfide,NiS)及反式二氢二醇环氧苯并芘(anti_7,8,_dihydrodiol_9,10_epoxidebenzo[a]pyrene,BPDE)恶性转化及成瘤的人支气管上皮细胞(Humanbronchialepithelial,16HBE)hMSH2基因启动子甲基化状况及其mRNA表达进行研究,探讨镍及反式_BPDE的表遗传致癌机制。材料与方法:采用甲基化特异性PCR(Methylation_specificPCR,MSP)法和RT_PCR法检测结晶型NiS及反式_BPDE恶性转化及成瘤的16HBE细胞hMSH2基因启动子甲基化状况及其mRNA表达,与非转化的16HBE细胞进行比较;并用去甲基化因子5_Azac(5_Aza_2′_deoxycytidine)处理有异常甲基化的细胞。结果:发现结晶型NiS及反式_BPDE恶性转化及成瘤的16HBE细胞hMSH2基因启动子区存在CpG岛的高甲基化;与非转化16HBE细胞比较,转化及成瘤的16HBE细胞hMSH2基因mRNA表达下降;有异常甲基化的细胞经去甲基化处理后甲基化消失。结论:结晶型NiS及反式_BPDE恶性转化及成瘤的16HBE细胞hMSH2基因启动子区CpG岛的高甲基化使其mRNA表达下降,并可能导致hMSH2基因表达抑制,这可能是结晶型NiS及反式_BPDE诱导16HBE细胞转化和成瘤的一种表遗传致癌机制。甲基化的可逆性对今后研究其表型逆转以及药物治疗提供了重要依据。
BACKGROUND & AIM: To investigate the malignant transformation of crystalline nickel sulfide (NiS) and trans-dihydric diol (anti_7,8, dihydrodiol_9,10_epoxidebenzo [a] pyrene, BPDE) and tumorigenic human bronchial epithelial (HumanBrownialepithelial, 16HBE) hMSH2gene promoter methylation and its mRNA expression study to explore nickel and trans-BPDE epigenetic carcinogenesis. MATERIALS AND METHODS: Methylation specific PCR (MSP) and RT_PCR methods were used to detect methylation status and mRNA expression of hMSH2 promoter in malignant transformation of NiS and trans-BPDE and tumorigenesis of 16HBE cells. Compared with non-transformed 16HBE cells; and abnormally methylated cells were treated with 5_Azac (5_Aza_2’deoxycytidine). Results: The hypermethylation of CpG islands in hMSH2 gene promoter was found in the malignant transformed and BPH-transformed 16HBE cells. Compared with untransformed 16HBE cells, the expression of hMSH2 mRNA in 16HBE cells transformed and tumorigenic decreased ; Methylation of abnormal methylation of cells after methylation disappeared. CONCLUSION: Hypermethylation of CpG island in hMSH2 promoter of malignant transformation of transmembrane and transmethylated trans-BPDE and malignant transformation of 16HBE cells may decrease the mRNA expression of hMSH2 gene and may result in the inhibition of hMSH2 gene expression, which may be due to the crystalline NiS and anti _BPDE induced 16HBE cell transformation and tumorigenesis of a phenotypic oncogenic mechanism. The reversibility of methylation provides an important basis for the future study of its phenotype reversal and drug treatment.