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Oncogene. 2004 Nov 11;23(53):8571-80.

The PI 3-kinase/Akt signaling pathway is activated due to aberrant Pten expression and targets transcription factors NF-kappaB and c-Myc in pancreatic cancer cells.

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1
Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.

Erratum in

  • Oncogene. 2005 Jun 16;24(26)4320.

Abstract

The persistent activation of signaling cascades results in dramatic consequences that include loss of cellular growth control and neoplastic transformation. We show here that phosphoinositide 3-kinase (PI 3-kinase) and its mediator Akt were constitutively activated in pancreatic cancer and that this might be due to the aberrant expression of their natural antagonist MMAC/PTEN. Indeed, our results show that MMAC/PTEN expression was either lost or significantly reduced in five of eight cell lines and in twelve of seventeen tumor specimens examined. That the poor expression of MMAC/PTEN in pancreatic cancer cells could be due to promoter methylation was indicated by methylation-specific PCR analysis. Our studies also indicated that PI 3-kinase targeted two important transcription factors in pancreatic cancer cells. The ability of constitutively activated NF-kappaB to induce gene expression and the stabilization of c-MYC protein by decreased phosphorylation of Thr58 were both dependent on PI 3-kinase activity. When pancreatic cancer cells were treated with a peptide antagonist of NF-kappaB nuclear translocation, or stably transfected with a dominant-negative mutant of MYC, their proliferation was markedly inhibited. Taken together, these data indicate that the aberrant expression of MMAC/PTEN contributes to the activation of the PI 3-kinase/Akt pathway and its transcription factor mediators in pancreatic cancer.

PMID:
15467756
DOI:
10.1038/sj.onc.1207902
[Indexed for MEDLINE]

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