三氧化二砷诱导MUTZ-1细胞凋亡的端粒酶调控研究

为了研究三氧化二砷（As2O3）诱导人类骨髓增生异常综合征难治性贫血伴原始细胞过多型（MDS—RAEB）细胞株MUTZ-1细胞凋亡的端粒酶调控机制，采用端粒重复序列扩增-酶联免疫吸附试验（TRAP—ELISA）检测端粒酶活性；RT—PCR法检测端粒酶逆转录酶（hTERT）、TRF1（TTAGGG repeat binding factor 1）、TRF2（TTAGGG repeat binding factor 2）、bcl-2、bax等基因mRNA水平的表达；磷脂酰丝氨酸（PS）转位等方法检测细胞凋亡，结果表明：1—8μmol／L As2O3诱导MUTZ-1细胞凋亡呈时间、浓度依赖关系。在该浓度范围内，As2O3可下调细胞端粒酶活性。且端粒酶活性下调与凋亡细胞阳性率呈明显负相关（r=一0．938，P=0．018）。MUTZ-1细胞经As，01作用后，hTERT基因mRNA表达下调，并与端粒酶活性变化呈正相关（r=0．783，P=0.022），但As2O3对TRF1及TRF2基因mRNA表达没有明显影响.MUTZ-1细胞端粒酶活性受抑制同时，伴有bcl-2 mRNA表达下调及bcl-2／bax比值下降结论：As2O3可能通过抑制细胞端粒酶活性及hTERT表达，诱导MUTZ-1细胞凋亡。As2O3抑制MUTZ-1细胞端粒酶活性可能是诱导该凋亡机制之一。

Study on the Mechanisms of Telomerase Regulations during Apoptosis of the Human MDS-RAEB Cell Line MUTZ-1 Cells Induced by Arsenic Trioxide

To investigate the mechanisms of the telomerase regulations during the apoptosis of the human MDS-RAEB cell line MUTZ-1 cells induced by arsenic trioxide (As(2)O(3)), telomerase activity was detected by TRAP-ELISA and the expressions of mRNAs of hTERT, TRF1 (TTAGGG repeat binding factor 1), TRF2 (TTAGGG repeat binding factor 2), bcl-2, and bax genes were detected by RT-PCR. Apoptosis was detected by translocation of phosphatidylserine (PS) by flow cytometry. The results showed that 1 - 8 micromol/L of As(2)O(3) induced typical apoptosis of MUIZ-1 cells in the dose-and time-dependent manners, the telomerase activity could be down-regulated at this concentration and negatively correlated with increased apoptosis (r = -0.938, P = 0.018). The expression of telomerase activity was positively related to the expression of hTERT (r = 0.783, P = 0.022), but As(2)O(3) had no effect on the mRNA expression of TRF1 and TRF2 genes. The inhibition of telomerase activity by As(2)O(3) on MUTZ-1 cells was accompanied with the low expression of bcl-2 gene and the decrease of bcl-2/bax ratio. It is concluded that the apoptosis of MUTZ-1cells induced by As(2)O(3) may occur via the inhibition of telomerase activity and down-regulation of the expression of hTERT mRNA, and this may be one of the mechanisms inducing apoptosis in MUTZ-1 cells treated by As(2)O(3).