Involvement of protein kinase Cdelta in contact-dependent inhibition of growth in human and murine fibroblasts

Oncogene. 2001 Aug 23;20(37):5143-54. doi: 10.1038/sj.onc.1204657.

Abstract

There is evidence that protein kinase C delta (PKCdelta) is a tumor suppressor, although its physiological role has not been elucidated so far. Since important anti-proliferative signals are mediated by cell-cell contacts we studied whether PKCdelta is involved in contact-dependent inhibition of growth in human (FH109) and murine (NIH3T3) fibroblasts. Cell-cell contacts were imitated by the addition of glutardialdehyde-fixed cells to sparsely seeded fibroblasts. Downregulation of the PKC isoforms alpha, delta, epsilon, and mu after prolonged treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA, 0.1 microM) resulted in a significant release from contact-inhibition in FH109 cells. Bryostatin 1 selectively prevented TPA-induced PKCdelta-downregulation and reversed TPA-induced release from contact-inhibition arguing for a role of PKCdelta in contact-inhibition. In accordance, the PKCdelta specific inhibitor Rottlerin (1 microM) totally abolished contact-inhibition. Interestingly, immunofluorescence revealed a rapid translocation of PKCdelta to the nucleus when cultures reached confluence with a peak in early-mid G1 phase. Nuclear translocation of PKCdelta in response to cell-cell contacts could also be demonstrated after subcellular fractionation by Western blotting and by measuring PKCdelta-activity after immunoprecipitation. Transient transfection of NIH3T3 cells with a dominant negative mutant of PKCdelta induced a transformed phenotype. We conclude that PKCdelta is involved in contact-dependent inhibition of growth.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells
  • Acetophenones / pharmacology
  • Active Transport, Cell Nucleus
  • Animals
  • Benzopyrans / pharmacology
  • Bryostatins
  • Cell Cycle
  • Cell Division / drug effects
  • Chemotaxis / drug effects
  • Down-Regulation
  • Enzyme Inhibitors / pharmacology
  • Fibroblasts / metabolism*
  • Fixatives / pharmacology
  • Glutaral / pharmacology
  • Humans
  • Isoenzymes / chemistry
  • Isoenzymes / metabolism*
  • Lactones / pharmacology
  • Macrolides
  • Mice
  • Mitogens / pharmacology
  • Protein Binding
  • Protein Isoforms
  • Protein Kinase C / chemistry
  • Protein Kinase C / metabolism*
  • Protein Kinase C-delta
  • Tetradecanoylphorbol Acetate / pharmacology
  • Time Factors

Substances

  • Acetophenones
  • Benzopyrans
  • Bryostatins
  • Enzyme Inhibitors
  • Fixatives
  • Isoenzymes
  • Lactones
  • Macrolides
  • Mitogens
  • Protein Isoforms
  • bryostatin 1
  • rottlerin
  • Prkcd protein, mouse
  • PRKCD protein, human
  • Protein Kinase C
  • Protein Kinase C-delta
  • Tetradecanoylphorbol Acetate
  • Glutaral