Inhibition of fatty acid synthase activity in prostate cancer cells by dutasteride

PURPOSE. With malignant progression to androgen independence, prostate cancer cells develop resistance to apoptosis and exhibit a variety of gene expression changes, including increased fatty acid synthase (FASN) expression. Increased FASN expression has been shown to correlate with poor prognosis, and correspondingly, the FASN gene has been proposed as a therapeutic target. Because FASN is an androgen regulated gene in the prostate, we have examined the effects of dutasteride on FASN in prostate cancer cells in vitro. Dutasteride is a novel dual inhibitor of the 5 alpha-reductase enzymes and is currently in use both for treatment of benign prostate hyperplasia (BPH) and in the reduction by dutasteride of prostate cancer events (REDUCE) prostate cancer prevention trial. METHODS. Microarray analysis was used to identify genes affected by treatment with dutasteride, followed by real time PCR confirmation. FASN expression at the protein level was examined using Western blotting and immunocytochernistry. Enzymatic activity of FASN was assayed by C-14-labeled malonyl-CoA incorporation. Viability after dutasteride treatment was assayed by MTS (Promega) and apoptosis via caspase 3/7 by DEVD cleavage assay. RESULTS. We have demonstrated that the 5 alpha-reductase inhibitor clutasteride, at clinically relevant levels, inhibits FASN mRNA, protein expression and enzymatic activity in prostate cancer cells. CONCLUSIONS. This is the first study to examine the effects of clinically relevant levels of dutasteride on prostate cancer cells at the molecular level and specifically, demonstrating the inhibition of FASN in these cells.