A K-ras oncogene increases resistance to sulindac-induced apoptosis in rat enterocytes

Gastroenterology. 1997 Dec;113(6):1892-900. doi: 10.1016/s0016-5085(97)70008-8.

Abstract

Background & aims: Mutations of c-K-ras occur commonly in colonic neoplasms. The aim of this study was to determine how c-K-ras mutations alter the responses to the chemopreventive agent sulindac.

Methods: The parental rat intestinal cell line IEC-18 and c-K-ras-transformed derivatives were treated with sulindac sulfide. Cell cycle distribution was determined by flow-cytometric analysis (fluorescence-activated cell sorter), apoptosis by DNA fragmentation (laddering), flow cytometry, and microscopy, and changes in gene expression by immunoblotting.

Results: Sulindac sulfide inhibited cell growth and induced apoptosis in a time- and dose-dependent manner more rapidly in and at lower concentrations in parental cells than ras-transformed cells. Expression of the sulindac sulfide arrested cells in G0/G1, but cells entered apoptosis throughout the cell cycle. Proapoptotic protein Bak was relatively high in untreated parental cells and increased markedly after sulindac sulfide but was low in untreated ras-transformed cells and did not increase after sulindac sulfide. Expression of other Bcl-2 family members was unchanged after sulindac sulfide. However, sulindac sulfide reduced levels of cyclin D1 protein and cyclin E- and cyclin D1-associated kinase activity.

Conclusions: c-K-ras-transformed enterocytes are relatively resistant to sulindac sulfide-induced growth inhibition and apoptosis, which may result from specific reduction of bak expression.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Anti-Inflammatory Agents, Non-Steroidal / pharmacology*
  • Apoptosis / physiology*
  • Cell Cycle / drug effects
  • Cell Division / drug effects
  • Cell Line, Transformed
  • Drug Resistance / physiology
  • Gene Expression Regulation / drug effects
  • Genes, ras / physiology*
  • Intestines / cytology
  • Intestines / drug effects*
  • Intestines / physiology*
  • Rats
  • Sulindac / pharmacology*

Substances

  • Anti-Inflammatory Agents, Non-Steroidal
  • Sulindac