贝伐单抗在胃癌疗效评价中的生物标志物研究

Identification of the biomarkers for evaluating the clinical efficacy of bevacizumab in the treatment of gastric cancer

目的 对贝伐单抗治疗人类胃癌动物模型进行疗效分析,并筛选有效的生物标志物,为临床胃癌贝伐单抗的个性化治疗奠定基础.方法 建立3种胃移植癌裸鼠模型并给予贝伐单抗治疗,通过荧光原位杂交（FISH）分析人类表皮生长因子（HER2）基因表达,酶联免疫吸附试验（ELISA）和实时定量聚合酶链反应（Real-time PCR）分别检测血清中人血管内皮生长因子（VEGF）、白细胞介素8（IL-8）、碱性成纤维细胞生长因子（bFGF）和鼠VEGF的含量和mRNA的表达.结果 对照组裸鼠HER2基因表达存在明显扩增,而经贝伐单抗治疗4周后,3种肿瘤细胞模型组未见HER2基因扩增;肿瘤组织及血清中人VEGF、人IL-8、人bFGF及鼠VEGF的表达水平均显著降低,其中SGC-7901细胞株对照组中组织人VEGF为（316.7±134.7） pg/mg蛋白,治疗模型组为（99.1±52.6）pg/mg蛋白,对照组血清人VEGF为（44.8±5.7） ng/L,治疗模型组为（21.4±6.21） ng/L;且其相应mRNA表达水平也明显下降.结论 贝伐单抗可抑制小鼠胃癌的形成,并且在此过程中VEGF、IL-8和bFGF mRNA和蛋白表达水平的下降起重要作用.

Objective To analyze the efficacy of bevacizumab in the treatment of gastric cancer in mouse model,and screen effective biomarkers to evaluate the curative effect,laying a foundation for the personalized therapy for gastric cancer with bevacizumab.Methods Three gastric cancer animal models were established by transplanting three human/mouse gastric cancer cell lines into nude mice,and treated with bevacizumab.The curative effect was assessed by the size and weight of the tumors.Finally,the common biomarkers were detected：the expression of human epidermal growth factor receptor-2 （HER2） was examined by fluorescence in situ hybridization （FISH） ; enzyme linked immunosorbent assay （ELISA） and real-time quantitative polymerase chain reaction （Real-time PCR） were respectively employed to detect the protein and mRNA expression of human vascular endothelial growth factor （VEGF）,interleukin （IL）-8,basic fibroblast growth factor （bFGF） and mouse VEGF.Results By FISH analysis,after treatment with bevacizumab for 4 weeks HER2 was undetectable in bevacizumab treated groups,but highly expressed in control group.Moreover,the mRNA and protein expression of human VEGF,IL-8,bFGF and mouse VEGF was reduced after treatment with bevacizumab.Specifically,in SGC-7901group after treatment with bevacizumab,the protein levels of human VEGF was decreased from （316.7 ± 134.7） pg/mg to （99.1 ± 52.6） pg/mg in tumor tissues,and those were declined from （44.8 ±5.7） ng/L to （21.4 ±6.21） ng/L in serum.Conclusion Bevacizumab can inhibit the formation of gastric tumor through down-regulating the mRNA and protein levels of VEGF,IL-8 and bFGF,suggesting that these three factors may act as important biomarkers in evaluating the clinical efficacy of bevacizumab in the treatment of gastric cancer.