Carcinogenesis Advance Access originally published online on April 29, 2007
Carcinogenesis 2007 28(8):1710-1717; doi:10.1093/carcin/bgm103
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Akt–GSK-3 pathway as a target in genistein-induced inhibition of TRAMP prostate cancer progression toward a poorly differentiated phenotype
Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center, 3900 Reservoir Road, NW, Washington, DC 20057, USA
* To whom correspondence should be addressed. Tel: +1 202 687 8611; Fax: +1 202 687 1823; Email: ppb{at}georgetown.edu
Anti-proliferative properties of genistein in prostate and other cancers have been studied extensively. However, the identification of genistein targets that may mediate its chemopreventive effects in vivo requires further elucidation. In this study, we have demonstrated that the incorporation of genistein in the diet of transgenic adenocarcinoma mouse prostate model (TRAMP/FVB) mice resulted in a reduction in prostate size and the incidence of poorly differentiated (PD) cancer ensuing in an accumulation of prostates at the prostatic intra-epithelial neoplasia (PIN) stage. TRAMP/FVB prostate cancer progression and the onset of PD cancer were characterized by the activation of acutely transforming retrovirus AKT8 in rodent T cell lymphoma (Akt), phosphorylation of glycogen synthase kinase 3-beta (GSK-3ß), post-transcriptional up-regulation of cyclin D1 and repression of cadherin-1 via snail-1 up-regulation. Incorporation of genistein in the diet significantly inhibited the activation of Akt, restored the activation of GSK-3ß, reduced cyclin D1 levels post-transcriptionally and maintained the expression of the cadherin-1 complex via down-regulation of snail-1. By identifying the Akt–GSK-3 pathway and subsequently its downstream effectors, as targets for genistein chemopreventive action, we have elucidated one possible mechanism by which genistein decreases the proliferative potential, retards cancer progression and maintains the integrity of the prostatic epithelial cells in vivo.
Abbreviations: Akt, acutely transforming retrovirus AKT8 in rodent T cell lymphoma; CaP, prostate cancer; DLP, dorsolateral prostate; EGF, epidermal growth factor; ER, estrogen receptor; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; GSK-3ß, glycogen synthase kinase 3-beta; IGF, insulin-like growth factor; PD, poorly differentiated; PIN, prostatic intra-epithelial neoplasia; TRAMP, transgenic adenocarcinoma mouse prostate
Received February 16, 2007; revised April 5, 2007; accepted April 19, 2007.