Biological effects of novel "combi-targeting" molecule and its effect on DNA repair pathway in hormone-refractory prostate cancer.

Objective: This study aimed to investigate the biological effects of “combi-targeting” JDF12 and its effect on the DNA repair pathway in hormone-refractory prostate cancer (HRPC). Methods: HRPC cell lines (PC3 cells and VCap cells) were treated with JDF12 at different concentrations, and SRB method was employed to detect the proliferation of HRPC cells; Annexin V-FITC kit was used to detect the apoptosis of PC3 cells; Alkaline comet assay was performed to detect DNA damage; Western blot assay was done to detect the expressions of autophosphorylated EGFR, XRCC1 and ERCC1 (later two are proteins in DNA repair pathway); the anti-tumor effect was evaluated in nude mice inoculated with PC3 cells. Results: JDF12 could inhibit the proliferation of PC3 cells and VCap cells in a concentration dependent manner (IC50: 14.04 ± 1.22 for PC3 and 15.57 ± 1.13 for VCap) and significantly increase the apoptotic cells as compared to those treated with mitozolomide or iressa alone. In PC3 cells, JDF12 induced DNA damage and also inhibited the expressions of phosphorylated EGFR, XRCC1 and ERCC1 in a concentration dependent manner. Moreover, JDF12 markedly inhibited tumor growth in nude mice. Conclusion: The novel “combi-targeting” JDF12 may exert more potent anti-proliferative effect as compared to mitozolomide or iressa alone, and the inhibitory effect on the EGFR signaling pathway and down-regulated XRCC1 and ERCC1 expressions may be ascribed to the JDF12 induced DNA damage.