Background & objective: Tetrandrine (Tet), a bisbenzylisoquinoline albaloid isolated from the Chinese herb "Hanfangji" (Radix Stephania Tetrandra), could effectively reverse P-glycoprotein-mediated multidrug resistance. This study was to investigate the reversal effect of tetrandrine on multidrug resistance of human epidermoid carcinoma cell line KB-MRP1.
Methods: The effects of tetrandrine on the proliferation of KB-3-1 and KB-MRP1 cells were observed by MTT assay. The inhibitory effects of cisplatin (DDP), vincristine (VCR), adriamycin (ADM) and etoposide (VP-16) used alone or in combination with tetrandrine on the proliferation of KB-3-1 and KB-MRP1 cells were evaluated by MTT assay. The effects of tetrandrine on ADM accmulation in KB-MRP1 cells and VCR-induced apoptosis were determined by flow cytometry (FCM).
Results: Tetrandrine at the concentration of 1.5 microg/ml and below showed no significant cytotoxicity to KB-3-1 and KB-MRP1 cells. The resistance of KB-MRP1 cells to VCR, ADM, VP-16 and DDP were 21.23, 38.39, 12.47 and 1.31 folds of that of KB-3-1 cells. When added 1 microg/ml tetrandrine, the chemosensitivity of KB-MRP1 cells to VCR, ADM and VP-16 were increased to 4.96, 5.85 and 4.24 folds, respectively; when added 1.5 microg/ml tetrandrine, the chemosensitivity of KB-MRP1 cells to VCR, ADM and VP-16 were much higher. When treated with 1.5 microg/ml tetrandrine, ADM accumulation in KB-MRP1 cells and the VCR-induced apoptosis were enhanced significantly.
Conclusion: Tetrandrine could moderately reverse the multidrug resistance of KB-MRP1 cells through increasing the accumulation of chemo-drugs in cells and promoting apoptosis.