CCL2 protects prostate cancer PC3 cells from autophagic death via phosphatidylinositol 3-kinase/AKT-dependent survivin up-regulation

J Biol Chem. 2008 Sep 5;283(36):25057-73. doi: 10.1074/jbc.M801073200. Epub 2008 Jul 8.

Abstract

Resistance to cell death is a hallmark of cancer. Autophagy is a survival mechanism activated in response to nutrient deprivation; however, excessive autophagy will ultimately induce cell death in a nonapoptotic manner. The present study demonstrates that CCL2 protects prostate cancer PC3 cells from autophagic death, allowing prolonged survival in serum-free conditions. Upon serum starvation, CCL2 induced survivin up-regulation in PC3, DU 145, and C4-2B prostate cancer cells. Both cell survival and survivin expression were stunted in CCL2-stimulated PC3 cells when treated either with the phosphatidylinositol 3-kinase inhibitor LY294002 (2 microm) or the Akt-specific inhibitor-X (Akti-X; 2.5 microm). Furthermore, CCL2 significantly reduced light chain 3-II (LC3-II) in serum-starved PC3; in contrast, treatment with LY294002 or Akti-X reversed the effect of CCL2 on LC3-II levels, suggesting that CCL2 signaling limits autophagy in these cells. Upon serum deprivation, the analysis of LC3 localization by immunofluorescence revealed a remarkable reduction in LC3 punctate after CCL2 stimulation. CCL2 treatment also resulted in a higher sustained mTORC1 activity as measured by an increase in phospho-p70S6 kinase (Thr389). Rapamycin, an inducer of autophagy, both down-regulated survivin and decreased PC3 cell viability in serum-deprived conditions. Treatment with CCL2, however, allowed cells to partially resist rapamycin-induced death, which correlated with survivin protein levels. In two stable transfectants expressing survivin-specific short hairpin RNA, generated from PC3, survivin protein levels controlled both cell viability and LC3 localization in response to CCL2 treatment. Altogether, these findings indicate that CCL2 protects prostate cancer PC3 cells from autophagic death via the phosphatidylinositol 3-kinase/Akt/survivin pathway and reveal survivin as a critical molecule in this survival mechanism.

Publication types

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

MeSH terms

  • Antibiotics, Antineoplastic / pharmacology
  • Autophagy* / drug effects
  • Autophagy* / genetics
  • Cell Line, Tumor
  • Cell Survival
  • Chemokine CCL2 / genetics
  • Chemokine CCL2 / metabolism*
  • Chemokine CCL2 / pharmacology
  • Culture Media, Serum-Free
  • Enzyme Inhibitors / pharmacology
  • Gene Expression Regulation, Neoplastic / drug effects
  • Gene Expression Regulation, Neoplastic / genetics
  • Humans
  • Inhibitor of Apoptosis Proteins
  • Male
  • Mechanistic Target of Rapamycin Complex 1
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism*
  • Multiprotein Complexes
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / metabolism*
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphoinositide-3 Kinase Inhibitors
  • Prostatic Neoplasms / genetics
  • Prostatic Neoplasms / metabolism*
  • Proteins
  • Proto-Oncogene Proteins c-akt / antagonists & inhibitors
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Ribosomal Protein S6 Kinases, 70-kDa / genetics
  • Ribosomal Protein S6 Kinases, 70-kDa / metabolism
  • Sirolimus / pharmacology
  • Survivin
  • TOR Serine-Threonine Kinases
  • Transcription Factors / antagonists & inhibitors
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Up-Regulation* / drug effects
  • Up-Regulation* / genetics

Substances

  • Antibiotics, Antineoplastic
  • BIRC5 protein, human
  • CCL2 protein, human
  • Chemokine CCL2
  • Culture Media, Serum-Free
  • Enzyme Inhibitors
  • Inhibitor of Apoptosis Proteins
  • Microtubule-Associated Proteins
  • Multiprotein Complexes
  • Neoplasm Proteins
  • Phosphoinositide-3 Kinase Inhibitors
  • Proteins
  • Survivin
  • Transcription Factors
  • Mechanistic Target of Rapamycin Complex 1
  • Proto-Oncogene Proteins c-akt
  • Ribosomal Protein S6 Kinases, 70-kDa
  • TOR Serine-Threonine Kinases
  • Sirolimus