title: LY294002 and metformin cooperatively enhance the inhibition of growth and the induction of apoptosis of ovarian cancer cells.
abstract: BACKGROUND
  The phosphoinositide 3 kinase (PI3K)/v-akt murine thymoma viral oncogene homolog (AKT)/mammalian target of rapamycin (mTOR) pathway is frequently aberrantly activated in ovarian cancer and confers the chemoresistant phenotype of ovarian cancer cells. LY294002 (PI3K inhibitor) and metformin (5'-adenosine monophosphate [AMP]-activated protein kinase [AMPK] activator) are 2 drugs that were known to inhibit mTOR expression through the AKT-dependent and AKT-independent pathways, respectively. In this study, we explored the effectiveness of LY294002 and metformin in combination on inhibition of ovarian cancer cell growth.
  
  
  METHODS
  Western blotting was used to detect the changes of PI3K/AKT/mTOR and AMPK/acetyl-CoA carboxylase (ACC) signaling activities, cell cycle control, and apoptosis. Cell growth was evaluated by cell proliferation, colony formation, and soft agar assays. Flow cytometry was used to study cell cycle distribution and cell death upon drug treatment.
  
  
  RESULTS
  Our study showed that LY294002 and metformin in combination could simultaneously enhance the repression of the PI3K/AKT/mTOR pathway and the activation of the AMPK/ACC pathway. The downstream target of AKT and AMPK, mTOR, was cooperatively repressed when the drugs were used together. The cell cycle regulatory factors, p53, p27, and p21, were up-regulated. On the other hand, caspase 3 and poly (ADP-ribose) polymerase activities involved in apoptosis were also activated. Cell growth assays indicated that LY294002 and metformin could effectively inhibit ovarian cancer cell growth. Flow cytometry analysis showed that the treatment of the 2 drugs mentioned above induced cell cycle arrest at G1 phase and increased sub-G1 apoptotic cells.
  
  
  CONCLUSIONS
  The combinational use of LY294002 and metformin can enhance inhibition of the growth and induction of the apoptosis of ovarian cancer cells. Our results may provide significant insight into the future therapeutic regimens in ovarian cancer.
authors.affiliation: Department of Obstetrics and Gynecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, People's Republic of China.
authors.forename: Cuilan
authors.initials: C
authors.lastname: Li
authors.forename: Vincent Wing Sun
authors.initials: VW
authors.lastname: Liu
authors.forename: David Wai
authors.initials: DW
authors.lastname: Chan
authors.forename: Kwok Ming
authors.initials: KM
authors.lastname: Yao
authors.forename: Hextan Yuen Sheung
authors.initials: HY
authors.lastname: Ngan
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000103:Acetyl-CoA Carboxylase / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects*; D014408:Biomarkers, Tumor / Q000378:metabolism; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002867:Chromones / Q000494:pharmacology* / Q000627:therapeutic use; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008687:Metformin / Q000494:pharmacology* / Q000627:therapeutic use; D009025:Morpholines / Q000494:pharmacology* / Q000627:therapeutic use; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000473:pathology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D055372:AMP-Activated Protein Kinases; D000103:Acetyl-CoA Carboxylase; D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D053148:Caspase 3; D002867:Chromones; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004791:Enzyme Inhibitors; D008687:Metformin; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D011065:Poly(ADP-ribose) Polymerases; D018809:Proliferating Cell Nuclear Antigen; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D016159:Tumor Suppressor Protein p53; C493956:CDKN1A protein, human; C413374:p27 antigen; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C546842:MTOR protein, human