Metformin inhibits the growth of anaplastic thyroid cancer cell by miRNA/mTOR pathway

Abstract

Objective To investigate the effect of metformin on the growth of human anaplastic thyroid cancer cell HTh74Rdox which is doxorubicin resistant. Methods The HTh74Rdox was treated with different concentrations of metformin for 48 h. Cell morphology was observed by microscope, cell viability was tested by methylthiazoletetrazolium (MTT), cell apoptosis by annexin Ⅴ and propidium iodide double staining, the anti-oncogenic miRNA was assayed by realtime fluorescence quantitative PCR (RT-PCR), and the adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signaling pathway tested by western blot. Furthermore, the anti-oncogenic miRNAs were knockdown by miRNA inhibitors (miR-34a, miR-101, miR-125b, and miR-138 inhibitors) and the cells were treated by metformin for 48 h, after that, cell apoptosis was detected by annexin Ⅴ and propidium iodide double staining, the expression of protein related to AMPK/mTOR signaling pathway was detected by western blot. Results Metformin inhibited the growth of human anaplastic thyroid cancer cell HTh74Rdox in a concentration-dependent manner, the cell apoptosis was induced by metformin, and there was a significantly lower expression of miR-34a, miR-101, miR-125b, and miR-138 in the HTh74Rdox. However, the four above miRNAs were upregulated by metformin, and AMPK/mTOR pathway was also activated by metformin. When these miRNAs were suppressed by miR-inhibitors (miR-34a, miR-101, miR-125b, miR-138 inhibitors), the stimulating effect of apoptosis and AMPK/mTOR pathway by metformin were reversed. Conclusion Metformin significantly suppresses cell viability of human anaplastic thyroid cancer cell HTh74Rdox, and stimulates AMPK/mTOR pathway and apoptosis by upregulating the expressions of miR-34a, miR-101, miR-125b, miR-138 in HTh74Rdox cell. (Chin J Endocrinol Metab, 2017, 33: 506-512) Key words: Metformin; Anaplastic thyroid cancer; miRNA; AMPK/mTOR