Trichomonas vaginalis: a possible foe to prostate cancer.

Prostate cancer (PCA) is the most common malignancy in men in USA, and the role of Trichomonas vaginalis (T. vag) in the development of PCA is still controversial. Clonogenic assay, PCNA staining, TUNEL staining and caspase-3 activity assay were used to investigate the in vitro role of T. vag in human prostate cancer. We further investigated the possible molecular mechanisms using RT-PCR and immunohistochemical staining. Culture supernatant of T. vag inhibits growth of PC-3 prostate cancer cells, and this correlated with upregulation of p21. Culture supernatant of T. vag induced apoptosis of PC-3 cells, and this correlated with downregulation of Bcl-2. The growth inhibition effect of culture supernatant of T. vag is also demonstrated in another prostate cancer cell line DU145, suggesting that its effect is not specific to one prostate cancer cell line. Culture supernatant of T. vag inhibits growth of prostate cancer by inhibition of proliferation and promotion of apoptosis. Such a study might be helpful to address the association between PCA and infection of T. vag.