Metformin Causes G1-Phase Arrest via Down-Regulation of MiR-221 and Enhances TRAIL Sensitivity through DR5 Up-Regulation in Pancreatic Cancer Cells

PLoS One. 2015 May 8;10(5):e0125779. doi: 10.1371/journal.pone.0125779. eCollection 2015.


Although many chemotherapeutic strategies against cancer have been developed, pancreatic cancer is one of the most aggressive and intractable types of malignancies. Therefore, new strategies and anti-cancer agents are necessary to treat this disease. Metformin is a widely used drug for type-2 diabetes, and is also known as a promising candidate anti-cancer agent from recent studies in vitro and in vivo. However, the mechanisms of metformin's anti-cancer effects have not been elucidated. We demonstrated that metformin suppressed the expression of miR-221, one of the most well-known oncogenic microRNAs, in human pancreatic cancer PANC-1 cells. Moreover, we showed that the down-regulation of miR-221 by metformin caused G1-phase arrest via the up-regulation of p27, one of the direct targets of miR-221. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is also a promising agent for cancer treatment. While recent studies showed that treatment with only TRAIL was not effective against pancreatic cancer cells, the present data showed that metformin sensitized p53-mutated pancreatic cancer cells to TRAIL. Metformin induced the expressions of death receptor 5 (DR5), a receptor for TRAIL, and Bim with a pro-apoptotic function in the downstream of TRAIL-DR5 pathway. We suggest that the up-regulation of these proteins may contribute to sensitization of TRAIL-induced apoptosis. The combination therapy of metformin and TRAIL could therefore be effective in the treatment of pancreatic cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / toxicity*
  • Apoptosis / drug effects
  • Apoptosis Regulatory Proteins / metabolism
  • Bcl-2-Like Protein 11
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Cyclin-Dependent Kinase Inhibitor p27 / metabolism
  • Down-Regulation / drug effects*
  • Drug Resistance, Neoplasm / drug effects
  • G1 Phase Cell Cycle Checkpoints / drug effects*
  • Humans
  • Membrane Proteins / metabolism
  • Metformin / toxicity*
  • MicroRNAs / antagonists & inhibitors
  • MicroRNAs / metabolism*
  • Oligonucleotides, Antisense / metabolism
  • Pancreatic Neoplasms / metabolism
  • Pancreatic Neoplasms / pathology
  • Proto-Oncogene Proteins / metabolism
  • Receptors, TNF-Related Apoptosis-Inducing Ligand / metabolism*
  • TNF-Related Apoptosis-Inducing Ligand / toxicity
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism
  • Up-Regulation / drug effects


  • Antineoplastic Agents
  • Apoptosis Regulatory Proteins
  • BCL2L11 protein, human
  • Bcl-2-Like Protein 11
  • MIRN221 microRNA, human
  • Membrane Proteins
  • MicroRNAs
  • Oligonucleotides, Antisense
  • Proto-Oncogene Proteins
  • Receptors, TNF-Related Apoptosis-Inducing Ligand
  • TNF-Related Apoptosis-Inducing Ligand
  • Tumor Suppressor Protein p53
  • Cyclin-Dependent Kinase Inhibitor p27
  • Metformin

Grants and funding

This work was supported by JSPS KAKENHI ( Grant Number 24689031. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.