Sildenafil increases chemotherapeutic efficacy of doxorubicin in prostate cancer and ameliorates cardiac dysfunction

Division of Cardiology, Department of Internal Medicine, Virginia Commonwealth University Pauley Heart Center, Richmond, VA 23298, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 09/2010; 107(42):18202-7. DOI: 10.1073/pnas.1006965107
Source: PubMed


We have shown that the potent phosphodiesterase-5 (PDE-5) inhibitor sildenafil (Viagra) induces a powerful effect on reduction of infarct size following ischemia/reperfusion injury and improvement of left ventricular dysfunction in the failing heart after myocardial infarction or doxorubicin (DOX) treatment. In the present study, we further investigated the potential effects of sildenafil on improving antitumor efficacy of DOX in prostate cancer. Cotreatment with sildenafil enhanced DOX-induced apoptosis in PC-3 and DU145 prostate cancer cells, which was mediated by enhanced generation of reactive oxygen species, up-regulation of caspase-3 and caspase-9 activities, reduced expression of Bcl-xL, and phosphorylation of Bad. Overexpression of Bcl-xL or dominant negative caspase 9 attenuated the synergistic effect of sildenafil and DOX on prostate cancer cell killing. Furthermore, treatment with sildenafil and DOX in mice bearing prostate tumor xenografts resulted in significant inhibition of tumor growth. The reduced tumor size was associated with amplified apoptotic cell death and increased expression of activated caspase 3. Doppler echocardiography showed that sildenafil treatment ameliorated DOX-induced left ventricular dysfunction. In conclusion, these results provide provocative evidence that sildenafil is both a powerful sensitizer of DOX-induced killing of prostate cancer while providing concurrent cardioprotective benefit.

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    • "The present studies grew out of those described in refs. (Das et al., 2010; Booth et al., 2014; Roberts et al., 2014), and were designed to determine whether PDE5 inhibitors enhanced celecoxib toxicity in tumor cells and if so, the molecular mechanisms by which the drugs interact. PDE5 inhibitors and celecoxib, in an NOS-dependent and COX2-independent fashion, killed multiple tumor cell types, including tumor stem cells and anoikis resistant tumor cells. "
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