Catalytically Active Peptidylglycine α-Amidating Monooxygenase in the Media of Androgen-Independent Prostate Cancer Cell Lines

Peptidylglycine α-amidating monooxygenase (PAM) converts inactive terminal-glycine prohormones into their activated α-amidated forms. PAM is thought to play a role in the development of antiandrogen drug resistance in prostate cancer (CaP) through PAM-activated autocrine growth. On the basis of the previous finding that many lung cancer cell lines excrete PAM into their culture media, this study investigates PAM levels in media collected from human CaP cell line cultures. Androgen-independent DU145 and PC-3 prostate cancer cell lines exhibited readily detectable levels of PAM activity in extracts and media, whereas the androgen-dependent LNCaP cell line showed little or no activity. Because of the much larger volume of media versus cell extracts, more than 90% of the total PAM activity was located in the media for both the PC-3 and DU145 cell lines, providing a readily accessible source of CaP PAM. A simple, scalable method to obtain PAM from the culture media of androgen-independent human prostate cancer cell lines is described in this article. This approach provides a much easier means of collecting CaP-derived PAM than previously described cell fractionation procedures and should facilitate the investigations of the role and targeting of PAM in hormone-independent CaP.