The therapeutic efficacy of I131-PSCA-mAb in orthotopic mouse models of prostate cancer.

BACKGROUND: Prostate stem cell antigen (PSCA) is upregulated in prostate cancer tissues. Here we aimed to study the therapeutic efficacy of a monoclonal antibody of PSCA-labeled I131 (I131-PSCA-mAb) in orthotopic mouse models of prostate cancer. METHODS: The proliferation, apoptosis and invasion abilities of PC-3 and LNCaP cells treated with I131-PSCA-mAb were measured by methyl thiazolyl tetrazolium assay, flow cytometry and transwell culture, respectively. The human prostate cancer models were established by orthotopic implantation of PC-3 and LNCaP cells in nude mice. I131-PSCA-mAb distribution and tumor cell apoptosis in the tumor-bearing nude mice were measured. RESULTS: The inhibitory and apoptosis rates of PC-3 and LNCaP cells treated with I131-PSCA-mAb reached a maximum of 84%, 80% and 50%, 46%, respectively, which were obviously higher than in the cells treated with I131-IgG or PSCA-mAb. The invaded number of PC-3 and LNCaP cells treated with I131-PSCA-mAbe was significantly reduced (P < 0.01) compared with the control group. The ratios of I131-PSCA-mAb in tumor to intramuscular I131-PSCA-mAb (T/NT) in tumor-bearing nude mice were increased with time and reached the highest level after 8 h. T/NT stayed above 3.0 after 12 h, and the tumor could still be developed after 24 h. The number of apoptotic cells in tumor tissue of nude mice treated with I131-PSCA-mAb was larger than that in the control group. CONCLUSION: I131-PSCA-mAb has the potential to become a new targeted therapy drug for the treatment of prostate cancer.