Vitamin D3 potentiates the growth inhibitory effects of metformin in DU145 human prostate cancer cells mediated by AMPK/mTOR signalling pathway

Clin Exp Pharmacol Physiol. 2015 Jun;42(6):711-7. doi: 10.1111/1440-1681.12409.


Metformin and vitamin D₃ both exhibit a strong antiproliferative action in numerous cancer cell lines, including in human prostate cancer cells. Here we showed that the combination of the two drugs had a much stronger effect on DU145 human prostate cancer cell growth than either drug alone. In this research, cell proliferation was measured by methylthiazol tetrazolium (MTT) assay. Cell apoptosis was determined with Hoechst 33342 staining. Western blotting and cell cycle analyses were used to elucidate potential mechanisms of interaction between the drugs. It is shown that in cultured DU145 cells, vitamin D₃ combined with metformin exhibits synergistic effects on cell proliferation and apoptosis. The underlying antitumor mechanisms may involve altered cycle distribution with a G1/S cell cycle arrest, activation of phospho-AMPK with subsequent inhibition of downstream mTOR signalling pathway, down-regulate c-Myc expression, and reducing the level of anti-apoptotic protein p-Bcl-2. In conclusion, metformin and vitamin D₃ synergistically inhibit DU145 cell growth, indicating a promising clinical therapeutic strategy for the treatment of androgen-independent prostate cancer.

Keywords: cell proliferation; metformin; prostate cancer; synergism; vitamin D3.

MeSH terms

  • AMP-Activated Protein Kinases / physiology*
  • Cell Cycle / drug effects
  • Cell Cycle / physiology
  • Cell Line, Tumor
  • Cholecalciferol / administration & dosage*
  • Dose-Response Relationship, Drug
  • Drug Synergism
  • Growth Inhibitors / administration & dosage*
  • Humans
  • Male
  • Metformin / administration & dosage*
  • Prostatic Neoplasms / drug therapy
  • Prostatic Neoplasms / metabolism*
  • Signal Transduction / drug effects
  • Signal Transduction / physiology
  • TOR Serine-Threonine Kinases / physiology*


  • Growth Inhibitors
  • Cholecalciferol
  • Metformin
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • AMP-Activated Protein Kinases