聚乙二醇交联血红蛋白辅助肿瘤化疗下调移植瘤模型中EPO/EPOR的表达

目的 检测血液代用品——聚乙二醇交联血红蛋白(PEG-Hb)联合顺铂对肿瘤促红细胞生成素及其受体(EPO/EPOR)表达和血管新生的影响.方法 HeLa细胞接种到裸鼠右腋下建立宫颈癌荷瘤模型.40只荷瘤裸鼠随机分为4组:对照组,顺铂(5 mg/kg)组,聚乙二醇交联血红蛋白组(0.6 g/kg),聚乙二醇交联血红蛋白(0.6 g/kg)联合顺铂(5mg/kg)组.治疗4周,观测绘制移植瘤生长曲线,计算各组肿瘤生长抑制率,CD31免疫组化染色定量分析瘤体微血管密度(MVD),免疫组化染色测定肿瘤组织低氧诱导因子-1α(HIF-1α)和EPO/EPOR的表达,Westem-blot分析肿瘤EPOR蛋白表达,ELISA测定血清中EPO含量.结果 PEG-Hb联合顺铂组(第4组)与其他各组比较瘤体明显缩小,CD31、HIF-1α和EPO/EPOR表达下调；第4组肿瘤组织内皮细胞EPOR表达较其他组明显降低；Western-blot测定EPOR蛋白表达在第4组明显降低,血清EPO水平也下降.结论 PEG-Hb具有辅助化疗增敏作用,抑制瘤体血管新生,下调EPO/EPOR的表达,为探讨PEG-Hb在辅助肿瘤化疗中的作用机制提供了依据.

PEG-conjugated hemoglobin with chemotherapy down regulate the EPO/EPOR expression in tumor xenograft model

Objective To observe the influence of polyethylene glycol-conjugated hemoglobin （PEG-Hb） solution combined with cisplatin on the expression of erythropoietin/erythropoietin receptor （EPO/EPOR） and tumor angiogenesis in cancer treatment. Methods HeLa cells were injected subcutaneously into the right oxter of 3-4 weeks old BALB/c nude mice to establish cervical tumor xenograft model. Then animals were randomly assigned to 4 groups （n=10） and treated respectively： group l（control）; group 2, cisplatin （5 mg/kg）; group 3, PEG- Hb （0.6 g/kg）; group 4 cisplatin （5 mg/kg） plus PEG-Hb （0.6 g/kg）. The volume of tumors in each groups were measured in 4 weeks treatment period. Efficacy was measured as percent tumor growth inhibition （TGI） relative to salinetreated group. CD31 was detected by immunohistochemistry and its expression was identified as microvascular density （MVD）. Expressions of hypoxia inducible factor-1α （HIF-1α） and EPO/EPOR in tumor tissues were analyzed by immunohistochemistry. EPOR protein level was tested by western blot. ELISA method was used in measuring EPO concentration in serum. Results Tumor volume was significantly decreased in group 4 compared with other groups. Immunoreactivity data demonstrated lower expression of CD31, HIF-1α and EPO/EPOR in group 4. The expression of EPOR in the endothelial cells was also significantly decreased in group 4. Western-blot data indicated lower EPOR protein level in group 4. Serum level of EPO was also decreased in group 4. Conclusion PEG-Hb plus cisplatin is benefit to tumor tissue oxygenation, therefore it can inhibit the tumor angiogenesis and down regulate the erythropoietin/erythropoietin receptor system. The result can provide more evidence for the enhanced sensitivity effect of the artificial oxygen carrier in cancer therapy.