ABSTRACT
Aim: To evaluate the effects of HZ08, a novel P-glycoprotein inhibitor, on reversing tumor resistance of K562/ADM to adriamycin in nude mice and on the activities of cytochromes P-450 (GYP) isoforms. Methods: Nude mice bearing K562/ADM were injected at different doses of HZ08 with adriamycin for 4 weeks. The tumor weights of HZ08 treatment groups were determined and compared to those of the control and positive groups. In addition, the effects of HZ08 were examined on GYP isoforms-mediated metabolism of specific substrates by GYP isoforms in rat liver microsomes in the presence or absence of HZ08. Results: The tumor weights of HZ08 treatment groups were significantly decreased and HZ08 was a relatively potent inhibitor of CYP3A4, with no significant effects on other isoforms tested. Conclusion: HZ08 has potent effects on reversing P-glycoprotein mediated tumor multidrug resistance in rive with little influence on cytoehrome P-450 activities of rat liver.