Cisplatin increases B-cell-lymphoma-2 expression via activation of protein kinase C and Akt2 in endometrial cancer cells

Int J Cancer. 2012 Apr 15;130(8):1755-67. doi: 10.1002/ijc.26183. Epub 2011 Aug 5.

Abstract

Human carcinomas often show resistance to cisplatin and Bcl-2 is associated with resistance to cisplatin. However, Bcl-2 regulation on cisplatin treatment in human cancers is unknown. Here, we show a novel mechanism by which cisplatin treatment promotes resistance by increasing the expression of Bcl-2 mRNA. Bcl-2 mRNA and protein expression was increased in cisplatin-resistant endometrial cancer cell lines (KLE and HEC-1-A), but not in cisplatin-sensitive cell line (Ishikawa). Cisplatin-mediated increase in Bcl-2 expression was blocked by combination with either actinomycin D or cycloheximide. In addition, Bcl-2 inhibition by HA14-1 led to increased cisplatin-induced apoptosis in KLE and HEC-1-A, whereas Bcl-2 overexpression in Ishikawa led to decreased cisplatin-induced apoptosis. Inhibition of protein kinase C (PKC) activity prevented cisplatin-dependant increase in Bcl-2 mRNA, and induced apoptosis in KLE cells. Furthermore, PKC inhibition was associated with decreased Akt and NF-κB activity. Cells stably expressing shRNA for Akt isoforms revealed that Akt2 was involved in cisplatin-dependant increase in Bcl-2 and apoptosis. Overexpression of Akt2 in Akt2-deficient cells led to increased Bcl-2 expression on cisplatin treatment. Our data suggest a novel regulation pathway of Bcl-2 by cisplatin, via the activation of PKC and Akt2, which has a profound impact on resistance to cisplatin-induced apoptosis in endometrial cancer cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology
  • Apoptosis / drug effects
  • Blotting, Western
  • Cell Line, Tumor
  • Cisplatin / pharmacology*
  • Drug Resistance, Neoplasm
  • Endometrial Neoplasms / genetics
  • Endometrial Neoplasms / metabolism
  • Endometrial Neoplasms / pathology
  • Enzyme Activation / drug effects
  • Female
  • Flow Cytometry
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • Naphthalenes / pharmacology
  • Protein Kinase C / antagonists & inhibitors
  • Protein Kinase C / metabolism*
  • Protein Kinase C-delta / antagonists & inhibitors
  • Protein Kinase C-delta / metabolism
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • RNA Interference
  • Reverse Transcriptase Polymerase Chain Reaction
  • Time Factors

Substances

  • Antineoplastic Agents
  • Naphthalenes
  • Proto-Oncogene Proteins c-bcl-2
  • AKT2 protein, human
  • Proto-Oncogene Proteins c-akt
  • Protein Kinase C
  • Protein Kinase C-delta
  • calphostin C
  • Cisplatin