瘦素上调乳腺癌细胞端粒酶的活性及其分子机制研究

摘要

Objective: The present work aims to explore the potential molecular mechanism of increasing telomerase activity induced by leptin in breast cancer cells in vitro. Methods: The leptin-mediated increase in telomerase activity in human breast cancer MCF-7 cells was determined using a TransAM enzyme-linked immunosorbent assay. Leptin-promoted human telomerase reverse tran-scriptase ( Htert ) expression and signal transducer and activator transcription 3 ( STAT3 ) were analyzed through real-time poly-merase chain reaction and Western blot analysis. Resnlts: Leptin improved the telomerase activity of MCF-7 cells in a dose-dependent manner. Telomerase activity increased 2.8-fold (P < 0.01 ) when the leptin concentration reached 10 nmol/L. ZMC-2, a leptin receptor monoclonal antibody, could significantly inhibit the leptin-induced activation of telomerase. Telomerase activity is closely related to the expression of Htert. Leptin not only enhances telomerase activity, but also upregulates the Htert Mrna level in a dose-dependent manner. After induction with 10 nmol/L leptin, the level of Htert protein increased 2.9-fold ( P < 0.01 ). Recently, STAT3 has been certified as a critical regulator of Htert. Meanwhile, with the leptin treatment, the Htert and phosphorylated STAT3 levels increased synchronously. This suggests that leptin-upregulated STAT3 may be involved in Htert overexpression. Conclnsion: Leptin promotes Htert expression in the MCF-7 human breast cancer cell line through the STAT3 pathway and ultimately increases telomerase activity.%目的:观察瘦素(leptin)对乳腺癌细胞端粒酶的活性影响,并探讨其可能的分子机制.方法:采用ELISA检测瘦素对人乳腺癌细胞MCF-7端粒酶活性的影响.应用实时荧光定量PCR和Western blot法测定瘦素对MCF-7细胞人端粒酶逆转录酶(hTERT)及STAT3 mRNA和蛋白表达水平的影响.结果:瘦素可增加MCF-7端粒酶的活性,且呈剂量依赖性,当浓度是10 nmol/L时,活性增加2.8倍;而采用瘦素受体单克隆抗体ZMC-2时则可明显抑制端粒酶的活性;端粒酶的活性与hTERT紧密相关,瘦素不仅增强了端粒酶的活性,同时也增加了hTERT mRNA的表达水平,且呈剂量依赖性,经瘦素10 nmol/L处理后,hTERT蛋白表达水平增加2.9倍;在瘦素处理MCF-7细胞后,hTERT的表达水平与磷酸化STAT3的水平呈现相关性上升,提示STAT3途径可能参与了瘦素诱导hTERT的表达.结论:在乳腺癌MCF-7细胞中,瘦素可能通过STAT3途径促进hTERT的表达,并最终上调端粒酶的活性.