硒对镉转化人支气管上皮细胞系16HBE凋亡和癌基因表达的影响

Effects of Selenium on Apoptosis and Proto-oncogene Expression in Cadmium-transformed 16HBE Cells

目的研究在体外染毒条件下硒对镉转化人支气管上皮细胞系16HBE凋亡和癌基因表达的影响。方法用0.625、1.25、2.5和5.0μmol/L亚硒酸钠染毒镉转化16HBE细胞24h,用流式细胞术检测凋亡,用RT-PCR检测p53,bcl-2和bax表达。结果 0.625、1.25、2.5和5.0μmol/L亚硒酸钠染毒镉转化16HBE细胞后,随硒剂量升高细胞凋亡率增高,相关系数r=0.987 9(P<0.01),并且在1.25、2.5和5.0μmol/L亚硒酸钠剂量组的凋亡率与对照组相比差异具有统计学意义(P<0.05或P<0.01)。亚硒酸钠可以抑制镉转化16HBE细胞p53和bcl-2的表达(P<0.05或P<0.01),bax表达虽有所增强但P>0.05。进行相关性分析,细胞凋亡与p53和bcl-2表达呈负相关,相关系数r分别为-0.923 6(P<0.01)和-0.862 1(P<0.05),而细胞凋亡与bax表达呈正相关,相关系数r=0.781 8(P<0.05)。p53表达和bcl-2表达呈正相关,相关系数r=0.894 1(P<0.05)。p53、bcl-2表达和bax表达之间呈显著负相关,相关系数分别为-0.822 2(P<0.05)和-0.961 3(P<0.01)。结论亚硒酸钠处理镉转化16HBE细胞,通过使p53和bcl-2表达下调、bax表达上调,诱导细胞凋亡从而起到抑制细胞恶性转化的作用。

Objective To investigate the effects of sodium selenite on apoptosis and expression of p53,bcl-2 and bax mRNA in cadmium-transformed 16HBE cells.Methods Apoptosis and expression of genes were measured after cultured cadmium-transformed 16HBE cells were exposed to sodium selenite at different doses（0.625,1.25,2.5 and 5.0 μmol/L Na2SeO3）for 24 h.Apoptosis was detected by using flow cytometry,and the expression levels of p53,bcl-2 and bax by using reverse transcription-polymerase chain reaction（RT-PCR）.Results Selenium at the doses of 0.625,1.25,2.5 and 5.0 μmol/L Na2SeO3 induced apoptosis in cadmium-transformed 16HBE cells,and statistic analysis yielded P0.05 or P0.01 in the groups of 1.25,2.5 and 5.0 μmol/L Na2SeO3.There existed an obvious dose-effect relationship between the selenium concentration and apoptosis rate with the relative coefficient being 0.987 9（P0.01）.The expression of p53 and bcl-2 mRNA was decreased（P0.05 or P0.01）,but that of bax mRNA was increased lightly（P0.05）after exposure to sodium selenite for 24 h,as compared with control group.Correlation analysis showed that there existed negative relationship between apoptosis rate and p53 expression（r=-0.923 6,P0.01）,and also existed negative relationship between apoptosis rate and bcl-2 expression（r=-0.862 1,P0.05）.Positive relationship was found between apoptosis rate and bax expression（r=0.781 8,P0.05）.Expression of p53 was positively related with bcl-2 expression（r=0.894 1,P0.05）.Expression of p53 and bcl-2 was negatively related with bax expression respectively and significantly,r=-0.822 2（p53：bax,P0.05）,r=-0.961 3（bcl-2：bax,P0.01）.Conclusion Selenium induces apoptosis by decreasing p53 and bcl-2 expression and increasing bax expression in cadmium-transformed 16HBE cells.Apoptosis induced by selenium plays an important role in inhibiting malignant transformation of cells.