J Cancer 2019; 10(7):1734-1744. doi:10.7150/jca.26380

Research Paper

Metformin Induces Apoptosis and Inhibits Proliferation through the AMP-Activated Protein Kinase and Insulin-like Growth Factor 1 Receptor Pathways in the Bile Duct Cancer Cells

Jin Lee1✉, Eun Mi Hong1, Jung Han Kim2, Jang Han Jung1, Se Woo Park1, Dong Hee Koh1, Min Ho Choi1, Hyun Joo Jang1, Sea Hyub Kae1

1. Division of Gastroenterology, Department of Internal Medicine, Hallym University College of Medicine, Gyeonggi-Do, Korea
2. Division of Gastroenterology, Department of Internal Medicine, Hallym University College of Medicine, Seoul, Korea

Abstract

Background/Aims: Metformin has been found to have antineoplastic activity in some cancer cells. This study was performed to determine whether metformin inhibits the proliferation of bile duct cancer cells by inducing apoptosis and its effects on the expression of gene-related proteins involved in cancer growth.

Methods: Human extrahepatic bile duct cancer cells (SNU-245 and SNU-1196) were cultured. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays were performed to determine the effect of metformin on the cell proliferation. Apoptosis was measured by a cell death detection enzyme-linked immunosorbent assay and a caspase-3 activity assay. Expression levels of various proteins, with or without specific small interfering ribonucleic acid-induced gene disruption, were measured by Western blot analysis. The migratory activity of the cancer cells was evaluated by wound healing assay.

Results: Metformin suppressed cell proliferation in bile duct cancer cells by inducing apoptosis. Metformin inhibited mammalian target of rapamycin (mTOR) by activation of tuberous sclerosis complex 2 (TSC-2) through phosphorylation of adenosine monophosphate-activated protein kinase at threonine-172 (AMPKThr172). Hyperglycemia impaired metformin-induced AMPKThr172 activation and enhanced phosphorylation of AMPK at serine-485 (AMPKSer485). Metformin blocked the inhibitory effect of insulin-like growth factor 1 receptor (IGF-1R)/insulin receptor substrate 1 (IRS-1) pathway on TSC-2, and hyperglycemia impaired metformin-induced inhibition of IGF-1R/IRS-1 pathway and modulated the invasiveness of bile duct cancer cells; however, this effect was impaired by hyperglycemia.

Conclusions: Metformin has antineoplastic effects in bile duct cancer, and hyperglycemic environment interrupts the effect of metformin. In addition, AMPK and IGF-1R play a key role in the proliferation of bile duct cancer cells.

Keywords: bile duct cancer, metformin, apoptosis, AMP-activated protein kinase, insulin-like growth factor 1 receptor

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How to cite this article:
Lee J, Hong EM, Kim JH, Jung JH, Park SW, Koh DH, Choi MH, Jang HJ, Kae SH. Metformin Induces Apoptosis and Inhibits Proliferation through the AMP-Activated Protein Kinase and Insulin-like Growth Factor 1 Receptor Pathways in the Bile Duct Cancer Cells. J Cancer 2019; 10(7):1734-1744. doi:10.7150/jca.26380. Available from http://www.jcancer.org/v10p1734.htm