Systemic administration of 4-amidinoindanon-1-(2'-amidino)-hydrazone, a new inhibitor of S-adenosylmethionine decarboxylase, produces cytostasis of human prostate cancer in athymic nude mice

CGP 48664A, a new S-adenosylmethionine decarboxylase inhibitor, blocks the production of spermidine and spermine, two polyamines that play critical roles in cellular proliferation. Under in vitro conditions, CGP 48664A produced cytostasis of the human prostate cancer cell lines LNCaP, LNCaP-LN3, PC-3M, and PC-3M-MM2 in a dose-dependent manner. This cytostasis was reversed by the addition of exogenous polyamines to the culture medium. LNCaP-LN3 cells or PC-3M-MM2 cells were implanted into the prostate of nude mice. Daily administration of CGP 48664A significantly inhibited tumor size and serum levels of prostate-specific antigen in mice implanted with LNCaP-LN3 cells. The therapeutic effect was related to the time the treatment was initiated, the volume of disease, and the length of treatment. CGP 48664A was not effective against the fast-growing PC-3M-MM2 tumor. These data suggest that to broaden its effectiveness, CGP 48664A should be combined with other cytoreductive agents.