Prevention of human prostate tumor metastasis in athymic mice by antisensetargeting of human angiogenin

Purpose: Angiogenin is a potent positive mediator of neovascularization, a process required for both primary tumor growth and metastasis. In the prese nt study, the effect of a fully phosphorothioated antisense oligodeoxynucle otide, designated JF2S, targeting the AUG translation initiation codon regi on of human angiogenin, on human prostate tumor development and metastasis in athymic mice was examined. Experimental Design: JF2S, was evaluated for its capacity to affect in vitr o synthesis or angiogenin and subsequent tumorigenicity of transiently tran sfected prostate tumor cells in mice. In vivo treatment experiments were th en conducted in which JF2S was used to prevent formation of tumors in an ec topic model and metastasis in an orthotopic model. Results: Transient transfection of tumor cells with JF2S inhibited both ang iogenin gene expression in vitro and tumorigenicity of these transfected ce lls in athymic mice. In therapy experiments, local treatment with JF2S comp letely protected mice from developing prostate tumors after s.c. injection of PC-3 human prostate tumor cells (P < 0.0001, survivor analysis). Most im portantly, systemic prophylactic administration of JF2S prevented, in 47% o f mice, formation of regional iliac lymph node micrometastases arising from primary tumors growing in the more natural orthotopic prostate setting (P = 0.0003, Fisher's exact test). Furthermore, total protection from regional metastasis occurred in those mice in which JF2S treatment successfully dim inished human angiogenin expression in vivo. Tumor-associated angiogenesis was also impaired by JF2S treatment. When therapy was delayed until all of the mice harbored primary tumors in the prostate, the incidence of regional metastasis was still significantly decreased (P < 0.005, survivor analysis ). Conclusions: These findings demonstrate that human prostate cancer establis hment and spread in athymic. mice is extremely susceptible to targeted disr uption of tumor-derived human angiogenin gene expression. Therefore, angiog enin is a valid target against which to devise preventative strategies for prostate cancer metastasis.