Abstract: Abstract: Objective: To study the mechanism of multidrug resistance of human glioma. Methods：The human glioma cells U251 and multidrug resistance cells U251/Dox were cultured in vitro. Accumulation and efflux ability of Rhodamine123 (Rh123) in U251 and U251/Dox cells were determined by flow cytometry；Multidrug resistance gene 1(mdr1) mRNA expression level in U251 and U251/Dox cells were measured by semi-quantitative reverse transcription and polymerase chain reaction (RT-PCR). Expression of P-gp was detected by immunohistochemistry. Results：MFI of U251 and U251/Dox cells were different；The mdr1 mRNA level in U251/Dox cells increased significantly. The expression of P-gp in U251 cells was significantly lower than U251/Dox cells. Conclusion: Human glioma develop cross-resistance to multiple tested cytotoxic agents and the possible molecular mechanism is involved with mdr1 mRNA overexpression and influence the function of P-glycoprotein.

Key words: Glioma, Multidrug resistance, P-gp, Flow cytometry, RT-PCR