摘要目的 探讨宫颈癌细胞中叶酸对DNA甲基转移酶1(DNMTl)和甲基化CpG岛结合蛋白2(MeCP2)表达的调节作用.方法 采用体外实验研究方法,对宫颈癌细胞Caski(HPV16阳性)和C33A(HPV阴性)进行不同浓度(10、50、100、500、750、1000 μg/ml)叶酸干预,分别采用Western blot和real-time PCR方法检测两种细胞中DNMT1和MeCP2蛋白的表达量和mRNA水平.结果 随着叶酸水平的升高,两种细胞的生长抑制率(C33A:r=0.984,P＜0.001；Caski:r=0.978,P=0.002)和凋亡率(C33A:r=0.989,P＜0.001；Caski:r=0.994,P＜0.001)均逐渐上升,DNMTl蛋白表达(C33A:r=-0.914,P＜0.001；Caski:r=-0.859,P=0.003)及MeCP2蛋白表达(C33A:r=-0.830,P=0.005；Caski:r=-0.981,P＜0.001)均呈逐渐降低趋势,而DNMT1和MeCP2 mRNA的Ct比值在两种细胞中的变化均无统计学意义(P＞0.05).相同叶酸浓度下,DNMT1蛋白和mRNA表达水平在Caski细胞均较C33A细胞为高,而MeCP2蛋白和mRNA表达水平则在C33A细胞较Caski细胞普遍为高.结论 补充叶酸可有效抑制宫颈癌细胞的增殖,促进凋亡,逆转DNMT1和MeCP2蛋白的异常表达；HPV16感染与DNMT1功能异常对宫颈癌的发生可能有协同效应.

abstractsObjective To explore the effects of folate on the expression of DNA methyltransferase 1 (DNMT1) and methyl-CpG-bingding protein 2 (MeCP2) in cervical cancer cell lines.Methods Experimental study was carried out in vitro.Human cervical cancer cell lines,including C33A cell with HPV negative and Caski cell with HPV16 positive,were treated with different concentration of folate.The expression of DNMT1 and MeCP2 protein (by Western blot)and mRNA (by real-time PCR) were then detected in the two cell lines.Results It was found that supplement of folate was able to reduce the cell proliferation in C33A cell (r=0.984,P＜0.001) and Caski cell (r=0.978,P=0.002),as well as induced the cell apoptosis (C33A:r=0.989,P＜0.001 ;Caski:r=0.994,P＜0.001).Results showed that the expression levels of DNMT1 protein (C33A:r=-0.914,P＜ 0.001 ; Caski:r=-0.859,P=0.003) and MeCP2 protein (C33A:r=-0.830,P=0.005 ;Caski:r=-0.981,P＜0.001) decreased gradually with the increase of folate concentrations,but the expression of DNMT1 and MeCP2 mRNA was not observed in Caski or C33A cell.When at the same levels of folate,the expression of DNMT1 protein or mRNA was higher in Caski cell than in C33A cell.However,the expression of MeCP2 protein or mRNA was higher in C33A cell than in Caski cell.Conclusion Our fimding indicated that adequate foleta could effectively inhibit the proliferation of cervical cancer cells and facilitate their apoptosis in vitro,thus would reverse the aberration protein expression of DNMTl and MeCP2.That there might be a synergistic action between HPV16 infection and parafunction of DNMT l in cervical cancer,being noticed.