Combination simvastatin and metformin synergistically inhibits endometrial cancer cell growth

Gynecol Oncol. 2019 Aug;154(2):432-440. doi: 10.1016/j.ygyno.2019.05.022. Epub 2019 Jun 6.

Abstract

Objective: Recent data show that simvastatin (SIM) and metformin (MET) have anti-proliferative effects in endometrial cancer cells. The combination (MET+SIM) inhibits tumor growth and metastasis in prostate cancer cells which possess similar molecular alterations to many early endometrial cancers. We tested the hypothesis that the anti-proliferative effects of MET+SIM in endometrial cancer cells would be greater than the effects of each agent alone.

Methods: RL95-2, HEC1B, and Ishikawa endometrial cancer cell lines were treated with MET and/or SIM. Growth inhibition was measured by MTS cell proliferation assays. Apoptosis was evaluated by caspase-3, Annexin V, and TUNEL assays and by apoptosis markers (BAX, Bcl-2, Bim) using western blot. Bim was silenced using Bim siRNA to confirm this apoptotic pathway. Treatment effects on the mTOR pathway were investigated by western blot using antibodies to phosphorylated (phospho)-AMPK and phospho-S6.

Results: MET+SIM synergistically inhibited growth in all three cell lines. The combination induced apoptosis as measured by TUNEL, Annexin V, and caspase-3 assays. Bim siRNA transfection abrogated this effect-silencing Bim in MET+SIM-treated RL95-2 cells rescued cell viability in MTS assays and reduced caspase-3 activity compared with control siRNA-transfected cells. Combination treatment upregulated phosphorylated AMPK and downregulated downstream phosphorylated S6, suggesting mTOR inhibition as a mechanism for these anti-proliferative effects.

Conclusions: MET+SIM treatment synergistically inhibits endometrial cancer cell viability. This may be mediated by apoptosis and mTOR pathway inhibition. Our results provide preclinical evidence that the combination of these well-tolerated drugs may warrant further clinical investigation for endometrial cancer treatment.

Keywords: Apoptosis; Endometrial cancer; Metformin; Statin; mTOR.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects*
  • Blotting, Western
  • Caspase 3 / metabolism
  • Cell Line, Tumor / drug effects
  • Drug Therapy, Combination
  • Endometrial Neoplasms / drug therapy*
  • Endometrial Neoplasms / genetics
  • Endometrial Neoplasms / pathology
  • Female
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Metformin / pharmacology*
  • Simvastatin / pharmacology*
  • TOR Serine-Threonine Kinases / metabolism

Substances

  • Metformin
  • Simvastatin
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • CASP3 protein, human
  • Caspase 3