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 transcriptase (hTERT) expression and signal transducer and activator transcription 3(STAT3) were analyzed through real-time polymerase chain reaction and Western blot analysis.

  Results  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.

  Conclusion  Leptin promotes hTERT expression in the MCF-7 human breast cancer cell line through the STAT3 pathway and ultimately increases telomerase activity.