Regulation of complement-dependent cytotoxicity by TGF-β-induced epithelial-mesenchymal transition.
Regulation of complement-dependent cytotoxicity by TGF-β-induced epithelial-mesenchymal transition.
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DOI：
10.1038/onc.2015.258
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发表时间：
2016-04-14
期刊：
影响因子：
8
通讯作者：
Keshamouni VG
中科院分区：
文献类型：
--
作者：
Goswami MT;Reka AK;Kurapati H;Kaza V;Chen J;Standiford TJ;Keshamouni VG
上皮-间质转化（Epithelial-mesenchymal transition， EMT）过程，除了是肿瘤转移的启动事件外，还涉及赋予癌细胞传播的一些临床相关特性。这些包括类似干细胞的特性，对靶向治疗的抵抗力以及逃避免疫监视的能力。对TGF-β诱导肺癌细胞EMT过程中基因表达变化的富集分析发现补体级联是显著富集的途径之一。对补体通路基因的进一步分析显示，补体抑制剂的表达增加，补体活性必需蛋白的表达减少。在这项研究中，我们测试了EMT是否赋予肺癌细胞对补体依赖性细胞毒性（CDC）的抗性并促进肿瘤进展。CD59是一种有效的膜攻击复合物抑制剂，介导补体依赖性细胞裂解。我们观察到TGF-β诱导EMT后细胞表面CD59表达显著增加。此外，CD59敲除恢复了EMT细胞对西妥昔单抗介导的CDC的易感性。TGF-β诱导的EMT中CD59的表达依赖于Smad3而不依赖于Smad2。ChIP分析证实Smad3直接结合CD59启动子。A549细胞中CD59的稳定敲除抑制了实验转移。这些结果表明，TGF-β诱导的EMT和CD59表达为肿瘤细胞的播散促进肿瘤进展提供了免疫逃避机制。总之，我们的数据表明，CD59抑制可以作为一种辅助手段，增强抗体介导治疗的疗效，并抑制肺癌的转移。
The process of Epithelial-mesenchymal transition (EMT), in addition to being an initiating event for tumor metastasis, is implicated in conferring several clinically relevant properties to disseminating cancer cells. These include stem cell like properties, resistance to targeted therapies and ability to evade immune surveillance. Enrichment analysis of gene expression changes during TGF-β induced EMT in lung cancer cells identified complement cascade as one of the significantly enriched pathway. Further analysis of the genes in the complement pathway revealed an increase in the expression of complement inhibitors and a decrease in the expression of proteins essential for complement activity. In this study, we tested whether EMT confers resistance to complement-dependent cytotoxicity (CDC) in lung cancer cells and promotes tumor progression. CD59 is a potent inhibitor of membrane attack complex that mediates complement-dependent cell lysis. We observed a significant increase in the CD59 expression on the surface of cells after TGF-β-induced EMT. Furthermore, CD59 knock down restored susceptibility of cells undergoing EMT to Cetuximab-mediated CDC. TGF-β-induced CD59 expression during EMT is dependent on Smad3 but not Smad2. ChIP analysis confirmed that Smad3 directly binds to the CD59 promoter. Stable knock-down of CD59 in A549 cells inhibited experimental metastasis. These results demonstrate that TGF-β-induced EMT and CD59 expression confers an immune evasive mechanism to disseminating tumor cells facilitating tumor progression. Together, our data demonstrates that CD59 inhibition may serve as an adjuvant to enhance the efficacy of antibody-mediated therapies, as well as to inhibit metastasis in lung cancer.