Rh. Medema et al., AFX-like Forkhead transcription factors mediate cell-cycle regulation by Ras and PKB through p27(kip1), NATURE, 404(6779), 2000, pp. 782-787
The Forkhead transcription factors AFX, FKHR and FKHR-L1 are orthologues of
DAF-16, a Forkhead factor that regulates longevity in Caenorhabditis elega
ns(1-3). Here we show that overexpression of these Forkhead transcription f
actors causes growth suppression in a variety of cell lines, including a Ra
s-transformed cell line and a cell line lacking the tumour suppressor PTEN.
Expression of AFX blocks cell-cycle progression at phase G(1), independent
of functional retinoblastoma protein (pRb) but dependent on the cell-cycle
inhibitor p27(kip1). Indeed, AFX transcriptionally activates p27(kip1), re
sulting in increased protein levels. We conclude that AFX-like proteins are
involved in cell-cycle regulation and that inactivation of these proteins
is an important step in oncogenic transformation.