Phosphodiesterase Type-5 Inhibitor Tadalafil Modulates Steroid Hormones Signaling in a Prostate Cancer Cell Line.

Background: The androgen receptor (AR) plays a key role in normal prostate homeostasis and in prostate cancer (PCa) development, while the role of aromatase (Cyp19a1) is still unclear. We evaluated the effects of a treatment with Tadalafil (TAD) on both these proteins.
Methods: Androgen-sensitive human PCa cell line (LnCAP) was incubated with/without TAD (10 ^-6 M) and bicalutamide (BCT) (10 ^-4 M) to evaluate a potential modulation on cell proliferation, protein and mRNA expression of Cyp19a, AR and estrogen receptor-β (ERβ), respectively.
Results: TAD increased early AR nuclear translocation ( p < 0.05, after 15 min of exposure), and increased AR transcriptional activity ( p < 0.05) and protein expression ( p < 0.05) after 24 h. Moreover, after 24 h this treatment upregulated Cyp19a1 and ERβ mRNA ( p < 0.05 and p < 0.005 respectively) and led to an increase in protein expression of both after 48 h ( p < 0.05). Interestingly, TAD counteracted Cyp19a1 stimulation induced by BCT ( p < 0.05) but did not alter the effect induced by BCT on the AR protein expression.
Conclusion: We demonstrate for the first time that TAD can significantly modulate AR expression and activity, Cyp19a1 and ERβ expression in PCa cells, suggesting a specific effect of these proteins. In addition, TAD potentiates the antiproliferative activity of BCT, opening a new clinical scenario in the treatment of PCa.