大黄素通过减少DNMTs的表达对胰腺癌细胞抑癌基因ppENK发挥去甲基化作用研究

Emodin plays a demethylation role in tumor suppressor gene ppENK by reducing the expression of DNMTs in pancreatic cancer cells

目的研究大黄素对胰腺癌细胞Panc1 DNA甲基转移酶(DNA methyltransferases,DNMTs)的影响,及其对抑癌基因前脑啡肽原(pre-proenkephalin,ppENK)启动子区CpG岛的去甲基化作用,探讨大黄素是否可通过降低DNMTs的表达逆转ppENK的甲基化状态。方法CCK-8检测不同浓度大黄素对Panc1细胞生长的影响,探索最佳用药浓度,重亚硫酸盐测序PCR(bisulfite genomic sequencing PCR,BSP)检测不同浓度大黄素对ppENK基因甲基化状态的影响,PCR和Western Blot检测ppENK及甲基转移酶DNMT1、DNMT3a的mRNA和蛋白表达情况。结果大黄素以时间梯度和浓度梯度依赖性抑制Panc1细胞生长,其半数最大抑制浓渡(half maximal inhibitory concentration,IC50)约为40μmol/L,大黄素可使ppENK甲基化状态减弱,非甲基化状态增强;可减弱DNMTs的mRNA和蛋白表达,增强ppENK mRNA和蛋白表达。结论大黄素可不同程度地使Panc1 ppENK抑癌基因去甲基化,使抑癌基因重新表达。大黄素抑制胰腺癌细胞生长和其去甲基化作用有关,推测大黄素发挥去甲基化作用和其抑制甲基转移酶表达相关。

Objective To study the effect of emodin on pancreatic cancer cell Panc1 DNA methyltransferases(DNMTs)and its demethylation of CpG island in the promoter region of tumor suppressor gene pre-proenkephalin(ppENK),and to explore whether emodin can reverse the methylation of ppENK by reducing the expression of DNMTs.Methods CCK-8 was used to detect the effect of different concentrations of emodin on the growth of Panc1 cells,and to explore the optimal drug concentration.Bisulfite genomic sequencing PCR(BSP)was used to detect the effect of different concentrations of emodin on the methylation status of ppENK gene.PCR and Western Blot were used to detect the mRNA and protein expression of ppENK and methyltransferases DNMT1 and DNMT3a.Results Emodin inhibited the growth of Panc1 cells in a time-dependent and concentration-dependent manner,half maximal inhibitory concentration(IC50)was approximately 40μmol/L,emodin can weaken the methylated state of ppENK and enhance the non-methylated state.Emodin can weaken the mRNA and protein expression of DNMTs and enhance the mRNA and protein expression of ppENK.Conclusion Emodin can demethylate the tumor suppressor gene of Panc1 ppENK in varying degrees and re-express the tumor suppressor gene.The inhibition of emodin on the growth of pancreatic cancer cells is related to its demethylation.It is speculated that the demethylation effect of emodin is related to its inhibition on the expression of methyltransferase.