Chronic but Not Acute Conjugated Linoleic Acid Treatment Inhibits Deoxycholic Acid-Induced Protein Kinase C and Nuclear factor-kappaB Activation in Human Colorectal Cancer Cells

Eur J Cancer Prev. 2006 Apr;15(2):125-33. doi: 10.1097/01.cej.0000195708.72072.42.

Abstract

Conjugated linoleic acid (CLA) has anti-carcinogenic effects in a variety of cancers including colon cancer. Secondary bile acids on the other hand are known as tumour promoters in colon cancer with effects on protein kinase C (PKC) and nuclear factor kappa B (NF-kappaB) signalling pathways. The aim of this study was to examine acute and chronic, isomer-specific effects of CLA on bile salt-induced PKC and NF-kappaB signal transduction in human colon cancer cells. HCT116 cells were treated with 100 mumol/l and 50 mumol/l cis-9,trans-11-CLA and trans-10,cis-12-CLA for 24 h and 14 days, respectively. The cells were then transfected with DNA coding for PKC beta1-EGFP (enhanced green fluorescent protein), PKC delta-EGFP or PKC zeta-EGFP fusion protein and activated with deoxycholic acid (DCA), phorbol myristate acetate (PMA) or C2-ceramide. PKC translocation was observed using real-time photomicroscopy and fluorescent microscopy and NF-kappaB analyses by gel shift assays. Chronic c-9,t-11-CLA and t-10,c-12-CLA treatment inhibited DCA-induced PKC beta1 and PKC delta translocation and also inhibited NF-kappaB activation. Acute CLA treatment had no effect on PKC or NF-kappaB activation. In conclusion this study indicates that chronic CLA treatment inhibits DCA-induced PKC and NF-kappaB activation in colon cancer cells. These data suggest mechanisms by which CLA may influence the course of colonic cancer.

MeSH terms

  • Colorectal Neoplasms
  • Deoxycholic Acid / antagonists & inhibitors*
  • Electrophoretic Mobility Shift Assay
  • Green Fluorescent Proteins / genetics
  • HCT116 Cells
  • Humans
  • Linoleic Acids, Conjugated / pharmacology*
  • NF-kappa B / metabolism*
  • Protein Kinase C / genetics
  • Protein Kinase C / metabolism*
  • Protein Kinase C beta
  • Protein Kinase C-delta
  • Signal Transduction
  • Tetradecanoylphorbol Acetate
  • Transfection

Substances

  • Linoleic Acids, Conjugated
  • NF-kappa B
  • enhanced green fluorescent protein
  • trans-10,cis-12-conjugated linoleic acid
  • Deoxycholic Acid
  • Green Fluorescent Proteins
  • Protein Kinase C
  • Protein Kinase C beta
  • Protein Kinase C-delta
  • Tetradecanoylphorbol Acetate