Background: Gastric cancer (GC) is one of the most common and lethal cancers and the prognosis of GC patients remains very poor. Cancer-associated fibroblasts (CAFs) largely facilitate the progression of GC but the underlying molecular mechanisms remain elusive despite numerous studies. Here, we investigated the role of CLIC1 in CAF activation and GC. Methods: qRT-PCR and western blot were performed to determine expression levels of cytokines, transcription factors and related proteins such as CAF markers. MTT assay was used to examine the proliferation of GC cells while transwell assay and tumorsphere formation assay were done to measure the migration, invasion and stemness of GC cells. Conditioned medium model was used to examine the intercellular communication between CAFs and GC cells. Results: Overexpression of CLIC1 in fibroblasts induced CAF activation and enhanced cell proliferation and migration. Also, CLIC1 up-regulated integrins/NF-κB signaling in CAFs. CLIC1-overexpressed fibroblasts promoted proliferation and migration of GC cells and up-regulated cancer stem cell markers and promoted EMT program of GC cells. IL-6 and IL-8 neutralizing antibodies inhibit the pro-tumor effects of CLIC1-overexpressing fibroblasts on GC cells. Further, knockdown CLIC1 in GC cells suppressed activation of CAF. Conclusions: CLIC1 overexpression activates CAF via up-regulating integrins/NF-κB signaling and activated CAF releases IL-6 and IL-8 to promote multiple malignant phenotypes of GC cells. These results implicate an essential role of CLIC1 in CAF activation and GC progression, which suggests that CLIC1 could serve as a potential target for GC therapy.

中文翻译：

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CLIC1通过整合素/NF-κB途径促进癌症相关的成纤维细胞活化和胃癌的进展

背景：胃癌（GC）是最常见和致命的癌症之一，GC患者的预后仍然很差。癌症相关的成纤维细胞（CAF）在很大程度上促进了GC的发展，但是尽管有大量研究，但潜在的分子机制仍然难以捉摸。在这里，我们研究了CLIC1在CAF激活和GC中的作用。方法：采用qRT-PCR和western blot方法检测细胞因子，转录因子及相关蛋白（如CAF标志物）的表达水平。用MTT法检测GC细胞的增殖，同时用transwell法和肿瘤球形成法检测GC细胞的迁移，侵袭和干性。条件培养基模型用于检查CAF和GC细胞之间的细胞间通讯。结果：CLIC1在成纤维细胞中的过表达诱导CAF活化并增强细胞增殖和迁移。而且，CLIC1上调了CAF中的整合素/NF-κB信号传导。CLIC1过表达的成纤维细胞促进了GC细胞的增殖和迁移以及癌干细胞标志物的上调，并促进了GC细胞的EMT程序。IL-6和IL-8中和抗体抑制过表达CLIC1的成纤维细胞对GC细胞的促肿瘤作用。此外，在GC细胞中敲低CLIC1抑制了CAF的激活。结论：CLIC1过表达通过上调整合素/NF-κB信号传导激活CAF，激活的CAF释放IL-6和IL-8以促进GC细胞的多种恶性表型。这些结果暗示了CLIC1在CAF激活和GC进程中的重要作用，