ABSTRACT
<p><b>OBJECTIVE</b>To 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.</p><p><b>METHODS</b>First 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.</p><p><b>RESULTS</b>SGC-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).</p><p><b>CONCLUSIONS</b>CW 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.</p>
Subject(s)
Animals , Mice , ATP Binding Cassette Transporter, Subfamily B, Member 1 , Metabolism , Cell Line, Tumor , Cisplatin , Therapeutic Uses , Curcuma , Drug Resistance, Multiple , Drug Resistance, Neoplasm , Drugs, Chinese Herbal , Pharmacology , Therapeutic Uses , Fluorouracil , Therapeutic Uses , Guanylate Cyclase , Mice, Nude , Receptors, Cytoplasmic and Nuclear , Soluble Guanylyl Cyclase , Stomach Neoplasms , Vincristine , Therapeutic UsesABSTRACT
<p><b>OBJECTIVE</b>To identify and elucidate the vasorelaxant activity of homoisoflavonoids, the main chemical components from Lignum Sappan (the stems of Caesalpinia sappan), in isolated rat thoracic aortic rings pre-contracted with phenylephrine (PE, 1 micromol x L(-1)) and KCl (60 mmol x L(-1)).</p><p><b>METHOD</b>The tension of rat thoracic aorta rings was used to evaluated the vasorelaxant activities of four homoisoflavonoids, brazlin (1), (E)-3-(3,4-dihydroxybenzylidene)-7-hydroxychroman-4-one (2), sappanone B (3), 3-deoxysappanone B (4).</p><p><b>RESULT</b>Cumulative addition of homoisoflavonoids (2, 3 and 4) (50-1000 micromol x L(-1)) exhibited an acute relaxation either in endothelium-intact or endothelium-denuded rings in a concentration-dependent manner. However, this relaxation was significantly inhibited in endothelium-denuded condition and in the presence of endothelial nitric oxide synthase (eNOS) inhibitor, N(W)-nitro-L-arginine methyl ester (L-NNA, 100 micromol x L(-1)), and a soluble guanylate cylcase (sGC) inhibitor, methylene blue (MB, 10 micromol x L(-1)) when addition of variation homoisoflavonoids brazlin (1) (50-1000 micromol x L(-1)).</p><p><b>CONCLUSION</b>These results indicate that normo-homoisoflavonoids (2, 3 and 4) from Caesalpinia sappan mediates endothelium-independent vasodilator action in rat thoracic aortic rings, while the variation homoisoflavonoids brazlin elicits endothelium-dependent relaxation might via nitric oxide (NO)-cGMP pathway. This research could explain the pharmacological activities of homoisoflavonoids to a certain degree.</p>