ABSTRACT
<p><b>OBJECTIVE</b>To investigate the reversing effect of icaritin on multidrug resistance of multiple myeloma cell lines KM3/BTZ and its underlying mechanism.</p><p><b>METHODS</b>KM3/BTZ cells were established by a gradually ascending gradient induction of bortezomib (BTZ). The sensitivities of KM3 and KM3/BTZ cells to 7 chemotherapeutic drugs, the inhibition and reversal effects of icaritin on proliferation and drug-resistance of KM3/BTZ cells were analyzed by MTT. The apoptosis was analyzed by flow cytometry, and the expression of Par-4, HSP27 and P-gp were detected by Western blot.</p><p><b>RESULTS</b>KM3/BTZ cells were not only resistant to BTZ, but also to other 6 chemotherapeutic drugs. The resistance index (RI) to BTZ was 17.84, and higher than that of other chemotherapeutic drugs. Icaritin inhibited the proliferation and induced the apoptosis of KM3/BTZ cells. The ICvalue of BTZ decreased from 0.345 µg/ml to 0.149 µg/ml, and the reversal index was 2.38 (P<0.05). The expression of Par-4 protein increased in a concentration-dependent manner, while the expression of HSP27 and P-gp were down-regulated.</p><p><b>CONCLUSION</b>Icaritin can inhibit cell proliferation and induce apoptosis of KM3/BTZ cells, moreover, can effectively reverse the multidrug resistance of KM3/BTZ cells. The mechanism may be related with down-regulation of HSP27 and P-gp expression, and up-regulation of Par-4 expression.</p>