The SLC35B2/YAP1 axis contributes to the inhibitory effects of CLIC-2-overexpressing cancer-associated fibroblast-derived exosomes on gastric cancer progression.

Cancer-associated fibroblasts (CAFs) are key regulators of tumor progression within the gastric cancer microenvironment. Chloride Intracellular Channel-2 (CLIC-2), a member of the CLIC protein family, has been implicated in tumor biology. However, its role in CAFs remains unclear. In this study, we found that CLIC-2 expression was significantly reduced in gastric CAFs and that low CLIC-2 levels were associated with poor patient prognosis. Loss-of-function experiments demonstrated that CLIC-2 deficiency promoted CAF-like activation of non-cancer fibroblasts (NFs), whereas CLIC-2 overexpression attenuated the activated phenotype of CAFs. Conditioned medium from CLIC-2-knockdown fibroblasts enhanced the viability, migratory, and invasion of gastric cancer cells, while conditioned medium from CLIC-2-overexpressing CAFs suppressed these malignant phenotypes. In vivo, co-injection of MKN-45 cells with CLIC-2-deficient fibroblasts promoted tumor growth and liver metastasis, whereas CLIC-2 overexpression in CAFs exerted tumor-suppressive effects. Proteomic analysis of CAF-derived exosomes identified Solute Carrier Family 35 Member B2 (SLC35B2) as a candidate downstream component associated with CLIC-2-regulated exosomal alterations. Exosomes derived from CLIC-2-overexpressing CAFs exhibited reduced SLC35B2 levels and inhibited malignant behaviors in gastric cancer cells. Mechanistically, SLC35B2 promoted YAP1 activation, as evidenced by enhanced nuclear accumulation of YAP1 and upregulation of its target genes CYR61 and CTGF. YAP1 silencing attenuated SLC35B2-induced malignant phenotypes, while SLC35B2 overexpression partially reversed the tumor-suppressive effects mediated by CLIC-2-overexpressing CAF-derived exosomes. Collectively, these findings suggest that CLIC-2 suppresses CAF-driven gastric cancer progression, at least partly through SLC35B2-associated regulation of YAP1 signaling, highlighting a potential stromal regulatory mechanism in gastric cancer.