OBJECTIVETo explore the reversal effect of multidrug resistance of Curcuma Wenyujin (CW) and its possible mechanism by establishing Vincristine-resistant gastric cancer SGC-7901 cells (SGC-7901/VCR) induced subcutaneous transplanted tumor in nude mice.

METHODSFirst we identified the resistance of SGC-7901/VCR by using methyl thiazolyl tetrazolium (MTT). The SGC-7901/VCR induced subcutaneous transplanted tumor model was established in 50 BALB/c nude mice by tissue block method. After 2 -3 weeks 36 mice with similar tumor size were selected and divided into 6 groups by random digit table, i.e., the model group, the Vincristine (VCR) group, the low dose CW group, the high dose CW group, the low dose CW combined VCR group, and the high dose CW combined VCR group, 6 in each group. Normal saline was intraperitoneally injected to mice in the model group at 10 mL/kg, once per 2 days. VCR was intraperitoneally injected to mice in the VCR group at 0.28 mg/kg once per 2 days. CW at 1.4 and 2.8 g/kg was administered to mice in the low and high dose CW groups by gastrogavage, 0.2 mL each time, once daily. CW at 1.4 and 2.8 g/kg was administered by gastrogavage and VCR was intraperitoneally injected at 0.28 mg/kg, once per 2 days to mice in the low dose CW combined VCR group and the high dose CW combined VCR group. All medication lasted for 14 days. The tumor growth was observed. The inhibition rate was calculated. Meanwhile, the positioning and expression of P-glycoprotein (P-gp) were detected by immunohistochemistry and Western blot.

RESULTSSGC-7901/VCR had strong resistance to VCR, Adramycin (ADM), fluorouracil (5-FU), and Cisplatin (DDP), especially to VCR. Proliferation activities of SGC-7901/VCR were significantly enhanced after drug elution. The tumor volume gradually increased as time went by. The tumor volume was the minimum in the high dose CW combined VCR group. The tumor volume was obviously reduced in the high dose CW combined VCR group with obviously reduced with increased inhibition rate of 51.56%, when compared with that of the model group and the VCR group (P < 0.05). Western blot test showed that, when compared with the model group, the gray level of P-gp in the VCR group increased (P < 0.05), and the relative expression of P-gp in the high dose CW group, the low dose CW combined VCR group, and the high dose CW combined VCR group significantly decreased (P < 0.05). Compared with the VCR group, the gray level of the P-gp decreased in the low dose CW group, the high dose CW group, the low dose CW combined VCR group, and the high dose CW combined VCR group (P < 0.05). Results of immunohistochemistry showed that, when compared with the model group, expression scores of P-gp in the high dose CW group, the low dose CW combined VCR group, and the high dose CW combined VCR group decreased with statistical difference (P < 0.05). Compared with the VCR group, expression scores of P-gp were obviously lowered in the low dose CW group, the high dose CW group, the low dose CW combined VCR group, and the high dose CW combined VCR group (P < 0.05).

CONCLUSIONSCW could reverse the drug resistance of SGC-7901/VCR subcutaneous transplanted tumor. And its mechanism might be related to down-regulating the expression of P-gp, suggesting that CW could be used as a kind of multidrug resistance reversal agent based on P-gp.