Abstract B97: Combination chemoprevention and underlying mechanisms of finasteride with NSAIDs using in vitro and in vivo models (Pten-/-) for prostate cancer
Authors: Narayanan Bhagavathi , Nargi Dominick , Narayanan Narayanan 
Published: May 2012

Abstract
B97

Background
The Prostate Cancer Prevention Trial (PCPT) in a total of 1,626 men demonstrated that finasteride, a 5α reductase inhibitor reduces prostate cancer risk by 24.8%, and however, it was associated with a risk of small increase in high-Gleason grade tumors. This suggests that although finasteride is a potential chemopreventive agent, prostate cancer risk factors are not limited its target. To enhance the efficacy of finasteride, earlier studies have successfully used the combination with flutamide for the treatment of advanced disease. Based on our successful attempts in testing the chemopreventive effects of NSAIDs in combination against prostate cancer, in this study, we tested the efficacy of finasteride with anti-inflammatory agents at low doses in preclinical models to synergistically decrease prostate cancer incidence.

Methods
To accomplish our goals, we examined the effects of finasteride individually and in combination with celecoxib or aspirin using in vitro and in vivo models. We used murine prostate cancer cells (CaP8) deleted for Pten-/- and human benign prostate hyperplastic epithelial cells (BPH1). The cells were pretreated for 24 h with testosterone before incubating with different doses of finasteride (15μM) or aspirin (40μM) or celecoxib (40μM) individually and in combination (half of each of the single dose) for 48 h. Effect on cell growth, cell cycle, apoptosis, molecular targets AR, AKT, Cyclin D1, COX-2 and serum PGE2 levels were analyzed with MTT, flow cytometry, Western blot and ELISA assays. To determine in vivo efficacy, four week old PTEN/KO mice (an immune-competent, orthotopic model) were administered (n=5/group) orally with finasteride (15mg/kg bw) or celecoxib (200 mg/kg bw) or aspirin (200 mg/kg bw) individually or in combinations with half of the single dose for a period of six weeks. Histopathological analysis of the DL prostate tissues was performed to determine the effect on the incidence of mPIN or adenocarcinoma stages. Specific immunohistochemical staining was performed to detect the molecular targets.

Results
Findings from MTT assays showed inhibition of CaP8 cell (Pten-/-) growth by 56% (P&lt;0.001) with finasteride in combination with aspirin in contrast to the effect (32%) exerted by finasteride alone. A similar effect (53%) was observed in celecoxib treated cells. Cell cycle analysis revealed G1 arrest with a decline in the “S” phase in all the treatments. Human BPH1 cells showed a significant inhibitory effect (65%) with finasteride in combination with aspirin, in contrast to the effect (25%) with finasteride alone. Histological determination of tumor incidence of mPIN showed a decrease by 5 fold in the group of mice that received dietary administration of finasteride in combination with aspirin or celecoxib after six 6 weeks in contrast to the mice that received finastride or aspirin alone (P&lt;0.001). Serum levels of PGE2 were reduced significantly in the finasteride and celecoxib combination group. Significance changes due to the treatment effect on tumor incidence and molecular targets will be discussed.

Conclusion
Finasteride in combination with anti-inflammatory agents, aspirin or celecoxib at low doses, synergistically prevents prostate cancer in preclinical models.
Citation Information: Cancer Prev Res 2008;1(7 Suppl):B97.