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.
ABSTRACT
Objective To establish a multidrug resistance cell line of human bladder tumor and study its characteristics and mechanism of muhidrug resistance. Methods Human bladder tumor cell line T24 was induced to muhidrug resistance cell line T24/ADM by intermittent administration of high dose ADM. The multidrug resistance to multianticancer agents of the ceils was evaluated by MTT assay; the expression of MDR gene was assessed by RT-PCR and P-gp expression was determined by flow cytometry. Results T24/ ADM resisted to many anti-tumor agents, and its IC50 of ADM was 16.3 times higher than that of T24. Significant overexpression of MDR gene and p-gp of the multidrug resistant cells were detected. Conclusion T24/ADM is a human muhidrug-resistant cell line, and it's drug resistance relates to the overexpression of MDR gene and p-gp.