重组人生长激素对荷人胃癌裸鼠移植瘤血管内皮生长因子表达的影响

Effects of recombinant human growth hormone on vascular endothelial growth factor expression of human gastric carcinoma xenografts in nude mice

目的研究重组人生长激素（rhGH）对生长激素受体（GHR）不同表达状态裸鼠人胃癌移植瘤生长及血管内皮生长因子（VEGF）表达的影响。方法采用免疫细胞化学染色法筛选出GHR阳性和阴性表达的细胞株各1株，分别接种于24只裸鼠皮下。将两种细胞接种裸鼠均随机分为对照组（0．9％NaCl，0．2ml／d）、低剂量rhGH组（0．5U·kg^-1·d^-1，0．2ml／d）和高剂量rhGH组（2．5U·kg^-1·d^-1，0．2mL／d）3组，每组8只，各组均连续给药14d，观察并记录裸鼠体重和肿瘤体积变化；采用酶联免疫吸附法测定各组裸鼠血清VEGF含量，免疫组织化学方法检测胃癌组织中VEGF蛋白表达，RT-PCR方法检测胃癌组织VEGFmRNA水平变化。结果筛选出GHR阳性表达的人胃癌细胞株SGC-7901和阴性表达的MKN-45。对于GHR^＋SGC-7901接种裸鼠，rhGH给药组皮下移植瘤体积较对照组增大（P〈0．05），且高剂量rhGH组促增长效应最为显著（P〈0．05），3组间体重差异无统计学意义（P〉0．05）；高剂量rhGH组的血清VEGF浓度为（252．94±15．32）ng／L，明显高于对照组的（49．94±5．73）ng／L和低剂量rhGH组的（167．60±9．54）ng／L（P〈0．05）；对照组VEGF表达为中度阳性，rhGH给药组呈强阳性；高剂量rhGH组肿瘤组织中VEGFmRNA相对表达量为0．6470±0．0447，明显高于对照组的0．3230±0．0258和低剂量rhGH组的0．4120±0．0351（P〈0．05）。对于GHR—MKN-45接种裸鼠，rhGH给药组体重明显大于对照组（P〈0．05）；肿瘤体积大小、血清VEGF水平、肿瘤组织VEGF蛋白及mRNA表达，3组间差异均无统计学意义（P〉0．05）。结论rhGH能促进GHR阳性表达的SGC-7901移植瘤生长，并促进VEGF表达增高；对于GHR阴性的MKN-45移植瘤，则没有表现出明显的促肿瘤生长及促VEGF表达效应。GHR存在可能是rhGH影响VEGF分泌的关键靶点。

Objective To investigate the effects of recombinant human growth hormone （rhGH） on tumor growth and vascular endothelial growth factor （VEGF） expression of human gastric carcinoma xenografts in nude mice with different expressions of growth hormone receptor （GHR）. Methods Immunocytochemical method was used to pick out one GHR-positive and one GHR-negative cell hne. Then the ceils were subcutaneously injected into 24 nude mice separately. The nude mice bearing two different kinds of human gastric caicinoma were equally randomized into control group （0.9% NaCl, 0.2ml/d）, low-dose rhGH group （0. 5 U· kg^- 1 ·d^- 1, 0.2 ml/d）, and high-dose rhGH group （2.5 U · kg^- 1 · d^- 1, 0. 2ml/d） and treated with drugs for 14 days. Changes of body weight and tumor volume of nude mice were recorded. Serum concentrations of VEGF in peripheral blood were analyzed by ELISA. VEGF protein and mRNA expression in tumor tissue were detected by immunohistochemistry and RT-PCR, respectively. Results We chose 5GC-7901 as GHR positive group, and MKN-45 as the negative one. For nude mice bearing GHR ^＋ SGC-7901 xenografts, the tumor volumes were significantly larger in rhGH groups than in control group （P 〈 0.05 ）, and the high-dose rhGH group revealed greater effect （ P 〈 0. 05 ）. Body weights were not significantly different among three groups （ P 〉 0. 05 ）. Serum VEGF concentration was （252.94 ± 15.32） ng/L in the high-dose rhGH group, which was significantly higher than that in control group [ （49.94 ± 5.73） ng/L] and low-dose rhGH group [ （ 167.60± 9.54） ng/L] （P 〈 0.05 ）. Moderate positive staining with VEGF was observed in the control group, while VEGF staining was strong in rhGH administration group. The relative expression of VEGF mRNA for the high-dose rhGH group was 0. 6470 ± 0.0447, which was significantly higher than that in control group （0. 3230 ±0. 0258 ） and low-dose rhGH group （0. 412 ±0. 0351 ） （P 〈 0.05）. While for nude mice bearing GHR-MKN-45 xenografts, the body weights of the rhGH-administrated groups were significantly higher than that of control group （ P 〈 0. 05 ）, while tumor growth, serum VEGF concentration, and the expressions of VEGF mRNA and protein in tumor tissue were not significantly different （P 〉 0. 05 ）. Conclusions rhGH can promote tumor growth and increase the expression of VEGF in the GHR-highly-expressed SGC-7901 xenograft tumor model. However, such effects do not exist in GHR-negatively-expressed MKN-45 xenograft tumor model. The existence of GHR may be a key target where rhGH influences the secretion of VEGF.