PTEN inhibits cell proliferation and induces apoptosis by downregulating cell surface IGF-IR expression in prostate cancer cells

Hong Zhao, Joelle Dupont, Shoshana Yakar, Michael Karas, Derek LeRoith

Research output: Contribution to journalArticle

Abstract

PTEN is a tumor suppressor gene that is frequently mutated in human tumors. It functions primarily as a lipid phosphatase and plays a key role in the regulation of phosphatidylinositol-3′-kinase. PTEN appears to play a crucial role in modulating apoptosis by reducing the levels of PtdIns(3,4,5)P3, a phospholipid that activates AKT, a central regulator of apoptosis. To understand the role of PTEN in regulating cell proliferation and apoptosis, we stably overexpressed PTEN in PC3 cells, which are prostate cancer cells that lack PTEN. Overexpression of PTEN in two different clones inhibited cell proliferation and increased serum starvation-induced apoptosis, as compared to control cells. Interestingly, PTEN overexpression resulted in a 44-60% reduction in total insulin-like growth factor-I receptor (IGF-IR) protein levels and a 49-64% reduction in cell surface IGF-IR expression. [ 35S]methionine pulse experiments in PC3 cells overexpressing PTEN demonstrated that these cells synthesize significantly lower levels of the IGF-IR precursor, whereas PTEN overexpression had no effect on IGF-IR degradation. Taken together, our results show that PTEN can regulate cell proliferation and apoptosis through inhibition of IGF-IR synthesis. These results have important implications for understanding the roles of PTEN and the IGF-IR in prostate cancer cell tumorigenesis.

Original languageEnglish (US)
Pages (from-to)786-794
Number of pages9
JournalOncogene
Volume23
Issue number3
DOIs
StatePublished - Jan 22 2004

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Keywords

  • Apoptosis
  • IGF-IR
  • PTEN
  • Prostate cancer
  • Protein synthesis

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Cancer Research

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