尼美舒利不依赖环氧合酶-2途径抑制胃癌生长的机制研究

Anti-cancer effect of Nimesulide and its COX-2-independent mechanisms

目的探讨选择性环氧合酶-2(COX-2)抑制剂尼美舒利不依赖COX-2途径抑制胃癌细胞移植瘤的可能机制。方法应用W estern-b lotting方法从人胃癌细胞株MKN45、AGS、MKN28、SGC-7901以及BGC-823中筛选出COX-2极低表达的细胞株MKN28,将其收集后皮下注射在BALB/C裸鼠的右侧前肢腋下。24只裸鼠分为模型组和干预组,干预组给予300 mg/L的尼美舒利灌胃,每日1次。每10天测定瘤体的大小,第40天终止实验,处置动物,留取移植瘤组织,免疫组化检测核因子-κB(NF-κB)和p21WAF1的表达;提取瘤组织总RNA进行RT-PCR,测定模型组和干预组过氧化物酶体增殖蛋白激活受体-γ(PPAR-γ)mRNA的表达水平。结果干预组移植瘤体积显著小于模型组(P<0.05),提示选择性COX-2抑制剂对MKN28胃癌细胞株裸鼠移植瘤模型具有良好的抑瘤作用。干预组NF-κB的表达显著低于模型组(P<0.05),p21WAF1的表达则显著高于模型组(P<0,05);RT-PCR发现干预组PPAR-γmRNA的表达较模型组增强。结论选择性COX-2抑制剂尼美舒利对COX-2表达水平极低的胃癌细胞株裸鼠移植瘤模型具有抑瘤作用。其机制可能是通过影响细胞凋亡相关蛋白p21WAF1的表达以及NF-κB和PPAR-γ转录因子等不依赖COX-2途径的作用得以实现。

Objective To elucidate the effect of a selective COX-2 inhibitor,Nimesulide,on the MKN28 cancer xenografts and its COX-2-independent mechanisms.Methods The western-blotting method was used to select the lowest COX-2 expression cell line from human gastric cancer cell lines of-MKN45,AGS,MKN28,SGC-7901 and BGC-823.Then the cell line was injected subcutaneously into the right forelimb of BALB/C athymic mice.Twenty-four athymic mice were divided into the model and treatment groups.300 mg/L nimesulide was orally administered to the mice of treatment group.The tumor volumes were measured every ten days and the mice were sacrificed after forty days.All tumors were dissected.The expressions of NF-κB and p21WAF1 were detected by immunohistochemical assays,and the expression of PPAR-γmRNA was detected by RT-PCR.Results The lowest expression of COX-2 of gastric cell lines was MKN28.Tumor volume of treatment group was significantly smaller than that of model group（P0.05）.Nimesulide can inhibit the growth of lowest-COX-2 expression MKN28 cancer xenografts.The expression of NF-κB in treatment group was significantly lower than that of model group（P0.05）,while the expression of p21WAF1 was significantly higher than that of model group（P0.05）,And the expression of PPAR-γmRNA was enhanced in treatment group.Conclusion Selective COX-2 inhibitor,Nimesulide,has anticancer effects on lowest-COX-2 expression MKN28 cancer xenografts.Nimesulide could induce enhancement of PPAR-γmRNA and p21WAF1 expression,and reduce the expression of NF-κB,that may contribute to its anti-tumor effect in a COX-2 independent pathway.