ASPP2基因及其甲基化在胃癌细胞中的表达及调节

Research on the expression and regulation of ASPP2 and its methylationin human gastric carcinoma cell

目的观察胃癌细胞中ASPP2基因与ASPP2基因启动子区域甲基化的表达及调节,探讨其与胃癌的关系。方法 Real-time PCR及亚硫酸氢盐测序法检测MKN-45和MGC-803两种胃癌细胞株及正常胃黏膜上皮细胞(GES-1细胞)中ASPP2基因的mRNA表达及启动子区域的甲基化状况;CCK-8法检测经过不同浓度的5-Aza-CdR(分别为:0.5、2.0、8.0、32.0及128.0 μmol/L)处理胃癌细胞后的生长抑制率,去甲基化处理后再次检测两种胃癌细胞中ASPP2基因的mRNA表达和甲基化状况。结果① MKN-45细胞、MGC-803细胞和GES-1细胞ASPP2 mRNA的相对表达量分别为1.130±0.053、0.993±0.051及2.121±0.047,MKN-45细胞及MGC-803细胞较GES-1细胞均显著降低,差异有统计学意义(P<0.01);两种胃癌细胞株ASPP2 mRNA的相对表达量相比,差异无统计学意义(P>0.05)。② MKN-45细胞、MGC-803细胞和GES-1细胞ASPP2的甲基化率分别为(11.73±0.69)%、(2.39±0.25)%、(1.92±0.15)%,MKN-45细胞较GES-1细胞显著升高,差异有统计学意义(P<0.01);MGC-803细胞较GES-1细胞差异无统计学意义(P>0.05);MKN-45细胞较MGC-803细胞显著升高,差异有统计学意义(P<0.01)。③在同一作用时间下,MKN-45细胞及MGC-803细胞各5-Aza-CdR浓度组的生长抑制率随着5-Aza-CdR处理浓度的增加而增加,呈药物浓度依赖性。④经24 μmol/L 5-Aza-CdR处理48 h后,MKN-45细胞、MGC-803细胞ASPP2 mRNA的相对表达量分别为1.842±0.026和1.106±0.043,MKN-45细胞较处理前显著升高,差异有统计学意义(P<0.01),MGC-803细胞较处理前差异无统计学意义(P>0.05);MKN-45细胞、MGC-803细胞ASPP2的甲基化率分别为(3.60±0.31)%、(2.23±0.11)%,MKN-45细胞较处理前显著降低,差异有统计学意义(P<0.01),MGC-803细胞较处理前差异无统计学意义(P>0.05)。结论① MKN-45细胞的ASPP2基因启动子区域的异常高甲基化可能是ASPP2基因mRNA表达降低的分子机制。②甲基化抑制剂5-Aza-CdR可抑制胃癌细胞MKN-45、MGC-803的生长;并促进MKN-45细胞ASPP2基因mRNA的表达,ASPP2基因启动子区域的甲基化逆转是其可能的机制。③ ASPP2基因启动子区域的异常高甲基化导致的mRNA表达降低可能与胃癌的发生相关。

Objective To investigate the relationship between the expression of ASPP2 mRNA and the methylation of ASPP2 gene in gastric cancer cells, to observe the inhibitory effect of 5-Aza-CdR on the growth of gastric cancer cells, to observe the effect of demethylation on the expression of ASPP2 mRNA and the methylation of ASPP2 gene in gastric cancer cells, and to explore the molecular mechanism of gastric cancer. Methods Real-time PCR was used to detect the expression of ASPP2 mRNA in two gastric cancer cells and normal gastric epithelial cells. BSP was used to detect the methylation of ASPP2 gene in two gastric cancer cells and normal gastric epithelial cells. CCK-8 was used to detect the growth inhibition rate of gastric cancer cells treated with 5-Aza-CdR of different concentrations, then they were used to detect expression of ASPP2 mRNA and the methylation of ASPP2 gene in gastric cancer cells again after the demethylation. Results ① The expression of ASPP2 mRNA in MKN-45 cells was significantly lower than that in GES-1 cells (P<0.01). The expression of ASPP2 mRNA in MGC-803 cells was significantly lower than that in GES-1 cells (P<0.01). There was no significant difference in MGC-803 cells and MKN-45 cells (P>0.05).② The methylation rate of ASPP2 in MKN-45 cells was significantly higher than that in GES-1 cells (P<0.01). The methylation rate of ASPP2 in MGC-803 cells was not significantly different from that in GES-1 cells (P>0.05). The methylation rate of ASPP2 in MKN-45 cells was significantly higher than that in MGC-803 cells (P<0.01).③ At the same time, the growth inhibition rate of each 5-Aza-CdR concentration group increased as the drug concentration depended.4.The expression of ASPP2 mRNA in MKN-45 cells was significantly higher than that before treatment (P<0.01), the expression of ASPP2 mRNA in MGC-803 cells was not significantly different from that before treatment (P>0.05). The methylation rate of ASPP2 in MKN-45 cells was significantly lower than that before treatment (P<0.01).The methylation rate of ASPP2 in MGC-803 cells was not significantly different from that before treatment (P>0.05). Conclusion ① Abnormal hypermethylation of ASPP2 gene in MKN-45 cells may be a molecular mechanism of decreased ASPP2 mRNA expression.② 5-Aza-CdR can inhibit the growth of MKN-45 and MGC-803 cells, and it can enhance the expression of ASPP2 mRNA in MKN-45 cells. Reversal of methylation in the promoter region of ASPP2 gene is the possible mechanism.③ Abnormal hypermethylation of the promoter region of ASPP2 gene may lead to silencing of mRNA expression that may be associated with gastric cancer.