PMID: 16619501Apr 20, 2006Paper

Tumour suppressor PTEN regulates cell cycle and protein kinase B/Akt pathway in breast cancer cells

Anticancer Research
Alice HlobilkovaZdenek Kolar

Abstract

PTEN is a tumour suppressor protein with phosphatase activity frequently altered in several types of human cancers. The PTEN effect was studied on the cell cycle (by bromdeoxyuridine incorporation) and on the phosphatidylinositol-3-kinase/protein kinase B/Akt (PI3-K/PKB/Akt) pathway regulating proteins (by immunocytochemical, Western blot analysis and kinase assay) upon transfection of wild-type PTEN and its mutant H123Y in breast cancer cell lines. The expression of the important proteins in the MCF-7 and BT-549 cells was characterised and the cellular localisation of PTEN was analysed. Transfection of H123Y led to the down-regulation of p27(Kip1) and p21(Waf1/Cip1) protein levels and the up-regulation of phosphorylated PKB/Akt. An overexpression of PTEN decreased cyclin E/cdk2 activity and inhibited S-phase entry in MCF-7. In BT-549 these changes were not observed, but overexpression of PTEN led to a diminution of PKB/Akt phosphorylation. PTEN function is mediated through the inhibition of the cell cycle and PKB/Akt phosphorylation in breast cancer cells.

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