RESEARCH ARTICLE A Potent Chemotherapeutic Strategy with Eg5 Inhibitor against Gemcitabine Resistant Bladder Cancer

Development of resistance to gemcitabine is a major concern in bladder cancer therapy, and the mechanism remains unclear. Eg5 has been recently identified as an attractive tar-get in cancer chemotherapy, so novel targeted chemotherapy with Eg5 inhibitor is expected to improve the anticancer effect in gemcitabine-resistant bladder cancer. In this research, RT112-Gr cells were 350-fold less sensitive to gemcitabine than the parental cell lines, while KU7-Gr cells were 15-fold less sensitive to gemcitabine than the parental cell lines. Human OneArray Microarray analysis was performed to obtain broad spectrum information about the genes differentially expressed in RT112 and RT112-Gr cells. The anti-proliferative activity of S(MeO)TLC, an Eg5 inhibitor, was analyzed in RT112-Gr cell lines using a cell viability assay. Furthermore, the inhibitory effect was evaluated in vivo using subcutaneous xenograft tumor model. According to the result of Human OneArray1GeneChip, RRM1 and RRM2 were up-regulated, while there was no significant change in Eg5. Trypan blue staining confirmed that in S(MeO)TLC and Gemcitabine combining S(MeO)TLC group cell viability were significantly decreased in RT112-Gr cells as compared with other groups. S (MeO)TLC and S(MeO)TLC+gemcitabine groups prominently suppressed tumor growth in comparison with other groups ’ in vivo. There were no significant differences in S(MeO)TLC and gemcitabine+S(MeO)TLC group in the effect of inhibition of bladder cancer in vivo and in vitro. Our data collectively demonstrated that S(MeO)TLC represents a novel strategy for the treatment of gemcitabine resistant bladder cancer