PKD, PKD2, and p38 MAPK mediate Hsp27 serine-82 phosphorylation induced by neurotensin in pancreatic cancer PANC-1 cells

J Cell Biochem. 2008 Feb 1;103(2):648-62. doi: 10.1002/jcb.21439.

Abstract

It is widely recognized that Hsp27 is a downstream substrate of the p38 MAPK cascade whereas the role of PKD family members in mediating receptor-stimulated Hsp27 Ser-82 phosphorylation has not been evaluated. Here, we show that neurotensin induced a rapid and striking increase in Hsp27 Ser-82 phosphorylation in PANC-1 cells, which was closely correlated with stimulation of activation loop phosphorylation of PKDs and p38 MAPK Thr180/Tyr182 phosphorylation. Treatment of PANC-1 cells with either the selective PKC inhibitor GF-I or the p38 MAPK inhibitor SB202190 partially reduced neurotensin-induced Hsp27 Ser-82 phosphorylation. However, treatment of the cells with a combination of GF-I and SB202190 virtually abolished neurotensin-induced Hsp27 Ser-82 phosphorylation. Overexpression of PKD in stably transfected PANC-1 cells increased the magnitude and prolonged the duration of Hsp27 Ser-82 phosphorylation in response to neurotensin. Either PKD or PKD2 gene silencing utilizing siRNAs targeting distinct PKD or PKD2 sequences reduced neurotensin-stimulated Hsp27 Ser-82 phosphorylation, but cotransfection of siRNAs targeting both, PKD and PKD2, markedly decreased neurotensin-induced Hsp27 Ser-82 phosphorylation. Knockdown of PKD and PKD2 abolished Hsp27 phosphorylation in cells treated with SB202190. Thus, neurotensin induces Hsp27 Ser-82 phosphorylation through p38 MAPK- and PKC/PKD-dependent pathways in PANC-1 cells. Our results demonstrate, for the first time, that neurotensin induces a striking increase in Hsp27 phosphorylation on Ser-82 in PANC-1 cells through convergent p38 MAPK, PKD, and PKD2 signaling.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Anisomycin / pharmacology
  • Carcinoma, Pancreatic Ductal / metabolism
  • Carcinoma, Pancreatic Ductal / pathology*
  • Cell Line, Tumor / drug effects
  • Cell Line, Tumor / metabolism
  • Heat-Shock Proteins / metabolism*
  • Humans
  • MAP Kinase Signaling System / drug effects
  • Neoplasm Proteins / physiology*
  • Neurotensin / pharmacology*
  • Pancreatic Neoplasms / metabolism
  • Pancreatic Neoplasms / pathology*
  • Phorbol 12,13-Dibutyrate / pharmacology
  • Phosphorylation / drug effects
  • Phosphoserine / metabolism
  • Protein Kinase C / antagonists & inhibitors
  • Protein Kinase C / genetics
  • Protein Kinase C / physiology*
  • Protein Kinase Inhibitors / pharmacology
  • Protein Kinases / genetics
  • Protein Kinases / physiology*
  • Protein Processing, Post-Translational / drug effects*
  • Protein Processing, Post-Translational / physiology
  • RNA Interference
  • RNA, Small Interfering / pharmacology
  • Recombinant Fusion Proteins / metabolism
  • Signal Transduction / drug effects
  • p38 Mitogen-Activated Protein Kinases / physiology*

Substances

  • Heat-Shock Proteins
  • Neoplasm Proteins
  • Protein Kinase Inhibitors
  • RNA, Small Interfering
  • Recombinant Fusion Proteins
  • Phosphoserine
  • Phorbol 12,13-Dibutyrate
  • Neurotensin
  • Anisomycin
  • Protein Kinases
  • protein kinase D2
  • protein kinase D
  • Protein Kinase C
  • p38 Mitogen-Activated Protein Kinases