Enhancing chemosensitivity in ABCB1- and ABCG2-overexpressing cells and cancer stem-like cells by an Aurora kinase inhibitor CCT129202.

Imidazopyridine CCT129202 is an inhibitor of Aurora kinase activity and displays a favorable antineoplastic effect in preclinical studies. Here, we investigated the enhanced effect of CCT129202 on the cytotoxicity of chemotherapeutic drugs in multidrug resistant (MDR) cells with overexpression of ATP-binding cassette (ABC) transporters and cancer stem-like cells. CCT129202 of more than 90% cell survival concentration significantly enhanced the cytotoxicity of substrate drugs and increased the intracellular accumulations of doxorubicin and rhodamine 123 in ABCB1 and ABCG2 overexpressing cells, while no effect was found on parental sensitive cells. Interestingly, CCT129202 also potentiated the sensitivity of cancer stem-like cells to doxorubicin. Importantly, CCT129202 increased the inhibitory effect of vincristine and paclitaxel on ABCB1 overexpressing KBv200 cell xenografts in nude mice and human esophageal cancer tissue overexpressing ABCB1 ex vivo, respectively. Furthermore, the ATPase activity of ABCB1 was inhibited by CCT129202. Homology modeling predicted the binding conformation of CCT129202 within the large hydrophobic cavity of ABCB1. On the other hand, CCT129202 neither apparently altered the expression levels of ABCB1 and ABCG2 nor inhibited the activity of Aurora kinases in MDR cells under the concentration of reversal MDR. In conclusion, CCT129202 significantly reversed ABCB1- and ABCG2-mediated MDR in vitro, in vivo and ex vivo by inhibiting the function of their transporters and enhanced the eradication of cancer stem-like cells by chemotherapeutic agents. CCT129202 may be a candidate as MDR reversal agent for antineoplastic combination therapy and merits further clinical investigation.