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Open Access Highly Accessed Research article

Simultaneous modulation of the intrinsic and extrinsic pathways by simvastatin in mediating prostate cancer cell apoptosis

Anna Goc12, Samith T Kochuparambil123, Belal Al-Husein12, Ahmad Al-Azayzih12, Shuaib Mohammad1 and Payaningal R Somanath1234*

Author affiliations

1 Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA, USA

2 Charlie Norwood VA Medical Center, Augusta, GA, USA

3 Department of Medicine, Georgia Health Sciences University, Augusta, GA, USA

4 Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, HM1200 – Georgia Health Sciences University, Augusta, GA, 30912, USA

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Citation and License

BMC Cancer 2012, 12:409  doi:10.1186/1471-2407-12-409

Published: 14 September 2012

Abstract

Background

Recent studies suggest the potential benefits of statins as anti-cancer agents. Mechanisms by which statins induce apoptosis in cancer cells are not clear. We previously showed that simvastatin inhibit prostate cancer cell functions and tumor growth. Molecular mechanisms by which simvastatin induce apoptosis in prostate cancer cells is not completely understood.

Methods

Effect of simvastatin on PC3 cell apoptosis was compared with docetaxel using apoptosis, TUNEL and trypan blue viability assays. Protein expression of major candidates of the intrinsic pathway downstream of simvastatin-mediated Akt inactivation was analyzed. Gene arrays and western analysis of PC3 cells and tumor lysates were performed to identify the candidate genes mediating extrinsic apoptosis pathway by simvastatin.

Results

Data indicated that simvastatin inhibited intrinsic cell survival pathway in PC3 cells by enhancing phosphorylation of Bad, reducing the protein expression of Bcl-2, Bcl-xL and cleaved caspases 9/3. Over-expression of PC3 cells with Bcl-2 or DN-caspase 9 did not rescue the simvastatin-induced apoptosis. Simvastatin treatment resulted in increased mRNA and protein expression of molecules such as TNF, Fas-L, Traf1 and cleaved caspase 8, major mediators of intrinsic apoptosis pathway and reduced protein levels of pro-survival genes Lhx4 and Nme5.

Conclusions

Our study provides the first report that simvastatin simultaneously modulates intrinsic and extrinsic pathways in the regulation of prostate cancer cell apoptosis in vitro and in vivo, and render reasonable optimism that statins could become an attractive anti-cancer agent.

Keywords:
Prostate cancer; Simvastatin; Docetaxel; Apoptosis; Bcl-2; Fas-L