CLIC1 facilitates cancer associated fibroblast activation and gastric cancer progression via integrins/NF-κB pathway.

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.