Phosphatidylinositol 3-kinase regulation of gastrin-releasing peptide-induced cell cycle progression in neuroblastoma cells

Titilope A. Ishola, Jung Hee Kang, Jingbo Qiao, B. Mark Evers, Dai H. Chung

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

Gastrin-releasing peptide (GRP), the mammalian equivalent of bombesin (BBS), is an autocrine growth factor for neuroblastoma; its receptor is up-regulated in undifferentiated neuroblastomas. Phosphatidylinositol 3-kinase (PI3K) is a critical cell survival pathway; it is negatively regulated by the PTEN tumor suppressor gene. We have recently found that poorly differentiated neuroblastomas express decreased PTEN protein levels. Moreover, overexpression of the GRP receptor, a member of the G-protein coupled receptor family, down-regulates PTEN expression, resulting in increased neuroblastoma cell growth. Therefore, we sought to determine whether GRP or BBS activates PI3K in neuroblastoma cells (BE(2)-C, LAN-1, SK-N-SH). GRP or BBS treatment rapidly increased phosphorylation of Akt and GSK-3β in neuroblastoma cells. Inhibition of GRP receptor, with antagonist GRP-H2756 or siRNA, attenuated BBS-induced phosphorylation of Akt. LY294002, a PI3K inhibitor, also abrogated BBS-stimulated phospho-Akt as well as its cell cycle targets. GRP increased G1/S phase progression in SK-N-SH cells. BBS-mediated BrdU incorporation was blocked by LY294002. Our findings identify PI3K as an important signaling pathway for GRP-mediated neuroblastoma cell growth. A novel therapy targeted at GRP/GRP receptor may prove to be an effective treatment option to inhibit PI3K in neuroblastomas.

Original languageEnglish (US)
Pages (from-to)927-932
Number of pages6
JournalBiochimica et Biophysica Acta - General Subjects
Volume1770
Issue number6
DOIs
StatePublished - Jun 1 2007

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Keywords

  • Akt
  • Bombesin
  • Cell cycle
  • GRP
  • Neuroblastoma
  • PI3K

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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