端粒在As_2O_3致L02和HepG2细胞凋亡及染色体畸变中的作用

Role of Telomere in Apoptosis and Chromosomal Aberrance of L02 and HepG2 Cells Induced by As_2O_3

目的探索端粒、端粒酶活性及端粒逆转录酶基因表达在As2O3诱导L02和HepG2细胞凋亡及染色体畸变过程中的作用。方法12μmol/L As2O3处理L02和HepG2细胞24、487、2 h,以处理0h作为对照组,流式细胞仪检测细胞凋亡;应用以PCR为基础的端粒重复序列扩增(TRAP-PCR)银染法检测端粒酶活性;逆转录聚合酶链反应(RT-PCR)检测端粒逆转录酶(hTERT)mRNA表达;0.625μmol/LAs2O3处理L02和HepG2细胞24、、6周,以处理0周作为对照组,染色体核型分析检测细胞染色体畸变;检测端粒酶活性及端粒逆转录(hTERT)mRNA表达。结果12μmol/L As2O3处理L02和HepG2细胞凋亡率较对照组增加(P<0.05);端粒酶活性及hTERTmRNA的表达较对照组均明显下降(P<0.05)。0.625μmol/L As2O3处理L02和HepG2细胞,染色体端-端融合及双微体的畸变率较对照组增加(P<0.05);端粒酶活性及hTERTmRNA的表达增加(P<0.05)。结论高浓度As2O3短期处理L02和HepG2细胞可诱导其凋亡。而低浓度As2O3长期处理L02和HepG2细胞可导致染色体畸变,畸变可使基因组不稳定是细胞癌变的基础。端粒、端粒活性及hTERTmRNA表达在此过程中的不同变化也许可部分解释As2O3抗癌和致癌的矛盾作用。

Objective To investigate the role of telomere, telomerase activity and telomerase reverse transcriptase mRNA expression in the process of apoptosis and chromosomal aberrance of L02 and HepG2 cells induced by arsenic. Methods： After cell lines L02 and HepG2 were treated with 12 μmol/L As2O3 for 24 h, 48 h, 72 h, the apoptosis was detected with flow cytometry. The expression of telomerase was measured by PCR based silver staining telomeric repeat amplification protocol. The expression of telomerase reverse transcriptase （hTERT） mRNA was determined with RT - PCR. Chromosome analysis was used to observe the chromosome aberration rates after L02 and HepG2 cells were treated with 0.625μmol/LAs2O3 for 2 w, 4 w, 6 w. The expression of telolnerase and telomerase reverse transcriptase（hTERT） mRNA were measured by TRAP- PCR and RT- PCR. Results： Flow cytometry analysis revealed that treated E02 and HepG2 cells with 12μmol/ LAs2O3 the apoptotic rates of treated groups were higher than tile control group （ P 〈 0.05 ）, Expression of telomerase and hTRETmRNA were decreased than the control group（ P 〈 0.05）. The chromosome aberration rates of double minute chromosomes and chromosome fusion of E02 and HepG2 ceils were increased than the control group with 0. 625μmol/LAs2O03 （ P 〈 0.05 ）. Expression of telomerase and hTRETmRNA were increased than the control group after E02 and HepG2 cells were treated with 0. 625μmol/ L As2O3 （P 〈 0.05）. Conclusion： High concentration arsenic could induce E02 and HepG2 cells apopto- sis. Low concentration arsenic could induce L02 and HepG2 cell chromosome aberration. Chromosome aberration could make genome instability and was the base of cell carcinogenesis. Alteration of telomerase activity and telomerase reverse transcriptase mRNA expression in this course may, in part, explain the paradoxical phenomena of arsenic actions in carcinogenic and anticancer effects.