BACKGROUND Bevacizumab or Avastin® (Av) is an anti-vascular endothelial growth factor agent. It does not improve survival of breast cancer patients due to development of refractoriness. Av treatment was shown to increase inflammation in a diabetic mouse model, and also to induce epithelial-to-mesenchymal transition of non-transformed breast epithelia. This study aimed to understand if the Av-induced inflammatory microenvironment could be a mechanism of Av refractoriness. Expression profiles of inflammatory mediators, in vitro in MDA-MB-231 cells, in vivo in a mouse model xenografted with MDA-MB-231 cells and from archived cases of human breast carcinoma tissues were evaluated. Gap junctions are also crucial for angiogenesis and tumor cell extravasation. The effect of connexin 43 (Cx43) overexpression on the expression of inflammatory markers in MDA-MB-231 cells treated with Av was assessed. METHODS MDA-MB-231 cells, control or overexpressing Cx43, were used in this study. Proliferation and invasion assays were performed. Quantitative PCR, ELISA and western blotting were performed to assess the regulation of inflammatory mediators and other factors upon Av treatment. Immunofluorescence was performed to document the translocation of Nuclear Factor-kappa B p65. RESULTS Breast cancer tissues had elevated transcriptional levels of inflammatory mediators. Av treatment increased expression levels of inflammatory mediators and metastatic factors in vitro and in vivo. Interestingly, overexpressing Cx43 in MDA-MB-231 cells alleviated the inflammatory effects induced by Av treatment. CONCLUSION This study attributes Av refractoriness to the Av therapy-induced inflammatory microenvironment.

中文翻译：

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贝伐单抗在MDA-MB-231乳腺癌细胞系和小鼠模型中诱导炎症。

背景技术贝伐单抗或Avastin®（Av）是一种抗血管内皮生长因子药物。由于难治性的发展，它不能提高乳腺癌患者的存活率。在糖尿病小鼠模型中，抗病毒治疗显示可增加炎症，并诱导未转化的乳腺上皮细胞由上皮向间充质转化。这项研究旨在了解Av诱导的炎症微环境是否可能是Av难治性的机制。评估了炎症介质在MDA-MB-231细胞中的体外，在异种移植了MDA-MB-231细胞的小鼠模型中以及来自人乳腺癌组织的存档病例中的体内表达情况。间隙连接对于血管生成和肿瘤细胞外渗也至关重要。评估了连接蛋白43（Cx43）过度表达对Av处理的MDA-MB-231细胞中炎症标志物表达的影响。方法采用MDA-MB-231细胞作为对照或过表达的Cx43。进行增殖和侵袭测定。进行定量PCR，ELISA和蛋白质印迹以评估Av治疗后炎症介质和其他因素的调节。进行免疫荧光以记录核因子-κBp65的易位。结果乳腺癌组织中炎症介质的转录水平升高。在体外和体内，抗病毒治疗增加了炎性介质和转移因子的表达水平。有趣的是，在MDA-MB-231细胞中过表达Cx43减轻了Av治疗诱导的炎症作用。