[Leptin promotes the expression of hTERT via STAT3 in breast cancer cells].

ABSTRACT

OBJECTIVE: To discussion the in vitro molecular mechanism of leptin promoting the expression of hTERT in breast cancer cells. METHODS: The hTERT mRNA expression of STAT3 knockdown on leptin-induced hTERT was measured by reverse transcription-polymerase chain reaction (RT-PCR). Determine the expression of hTERT protein after different treatments in MCF7 by Western blot. Chromatin immunoprecipitation assay (ChIP) was performed to detect the binding of STAT3 to hTERT promoter in MCF7. Luciferase assay was used to confirm the effects of leptin and STAT3 phosphorylation inhibitor on the transcriptional activity of hTERT promoter. RESULTS: The RT-PCR analysis showed that knockdown of STAT3 significantly reduced the leptin-induced transcription of hTERT. Western blot showed that the expression of hTERT were 3.109 ± 0.051 and 1.025 ± 0.031 after leptin or both of leptin and AG490 treatments. The results of CHIP showed that the mRNA of control and leptin (160 ng/ml) treatment were 1 and 3.311 ± 0.017. Leptin increased the combination of STAT3 and hTERT promoter. Luciferase assay showed that when the concentration of leptin was 160 ng/ml, the hTERT promoter activity was 80.98 ± 0.18 while the control was 20.76 ± 0.31. After AG490 treatment, the hTERT promoter activity was 18.65 ± 0.32,significantly reduced the leptin-induced activity of hTERT promoter. CONCLUSION: Leptin/STAT3 signaling is a novel pathway for the up-regulation of hTERT expression in breast cancer cells.