Activation of PI3K/Akt Pathway by PTEN Reduction and PIK3CA mRNA Amplification Contributes to Cisplatin Resistance in an Ovarian Cancer Cell Line

Gynecol Oncol. 2005 Apr;97(1):26-34. doi: 10.1016/j.ygyno.2004.11.051.

Abstract

Objective: The aim of this study was to understand the role of PIK3CA and PTEN on the resistance of human ovarian cancer cells to cisplatin-induced apoptosis.

Methods: Human ovarian cancer cell OVCAR-3 and cisplatin-resistant subclone OVCAR-3/CDDP cells were used for these studies. The expressions of apoptosis regulating proteins and PI3K/Akt signaling proteins were systematically examined.

Results: OVCAR-3/CDDP cells were 4.8-fold more resistant to cisplatin compared to OVCAR-3 cells following 72 h exposure to this drug. This resistance was paralleled with reduced susceptibility to cisplatin-induced apoptosis. Apoptotic proteins were differentially expressed in OVCAR-3/CDDP cells, resulting in the inhibition of Bax translocalization. Cisplatin inhibited Akt phosphorylation and activation in OVCAR-3 cells but not in OVCAR-3/CDDP cells. The specific PI3K inhibitors LY294002 and wortmannin sensitized OVCAR-3/CDDP cells to cisplatin-induced apoptosis and decreased cell viability. A low level of PTEN expression was strongly associated with amplified PIK3CA and PI3K/Akt activities in OVCAR-3/CDDP cells. Small interfering RNA knockdown of PTEN and the expression of active p110alpha resulted in a blockade of apoptosis by cisplatin in OVCAR-3 cells.

Conclusions: These results collectively indicate that the development of resistance in OVCAR-3 cells was derived by increased PIK3CA transcription and reduction of PTEN expression. These alterations conferred cisplatin resistance to cisplatin through the activation of PI3K/Akt and the inhibition of Bax translocation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects
  • Biomarkers, Tumor / biosynthesis
  • Biomarkers, Tumor / genetics*
  • Cell Line, Tumor
  • Cisplatin / pharmacology*
  • Class I Phosphatidylinositol 3-Kinases
  • Drug Resistance, Neoplasm
  • Enzyme Activation
  • Female
  • Gene Amplification
  • Humans
  • Intracellular Membranes / metabolism
  • Mitochondria / metabolism
  • Ovarian Neoplasms / drug therapy*
  • Ovarian Neoplasms / enzymology
  • Ovarian Neoplasms / genetics
  • Ovarian Neoplasms / metabolism*
  • Oxidation-Reduction
  • PTEN Phosphohydrolase
  • Phosphatidylinositol 3-Kinases / biosynthesis
  • Phosphatidylinositol 3-Kinases / genetics*
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphoric Monoester Hydrolases / metabolism*
  • Protein-Serine-Threonine Kinases / metabolism*
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-akt
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / genetics
  • Transcription, Genetic / drug effects
  • Tumor Suppressor Proteins / metabolism*
  • bcl-2-Associated X Protein
  • bcl-X Protein

Substances

  • BAX protein, human
  • BCL2L1 protein, human
  • Biomarkers, Tumor
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Messenger
  • Tumor Suppressor Proteins
  • bcl-2-Associated X Protein
  • bcl-X Protein
  • Phosphatidylinositol 3-Kinases
  • Class I Phosphatidylinositol 3-Kinases
  • PIK3CA protein, human
  • AKT1 protein, human
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Phosphoric Monoester Hydrolases
  • PTEN Phosphohydrolase
  • PTEN protein, human
  • Cisplatin