ARHGAP12 loss promotes tumor budding and lymphatic metastasis in gastric cancer

Background Identifying the molecular drivers of metastasis and tumor budding (Tb) is essential for improving patient outcomes. This study aimed to characterize the expression pattern and functional contribution of ARHGAP12, a Rho GTPase-activating protein, in the metastatic evolution of GC. Methods ARHGAP12 expression profiles were analyzed using TCGA_STAD and scRNA-seq (GSE163558) datasets. The spatial distribution of ARHGAP12 in Tb regions and paired lymph node metastases was validated via mIHC in a cohort of 27 GC patients. A highly metastatic cell subline (HGC-27-L) was established through in vivo selection. Functional impacts of ARHGAP12 were evaluated using siRNA knockdown, lentiviral overexpression, wound healing, Transwell migration, and transendothelial migration assays. The prognostic value of ARHGAP12 was assessed using Kaplan-Meier survival analysis. Results Analysis of scRNA-seq and mIHC data revealed that ARHGAP12 expression was significantly diminished in metastatic foci and Tb cells compared to primary tumor cells ( P < 0.01). The HGC-27-L subline exhibited lower ARHGAP12 levels than its parental line. Functional assays demonstrated that ARHGAP12 knockdown markedly promoted the migration and invasion of AGS cells ( P < 0.01). Conversely, overexpressing ARHGAP12 in HGC-27-L and MKN-45 cells inhibited motility and transendothelial migration ( P < 0.01) by stabilizing cell-cell junctions and upregulating E-cadherin. Clinically, low ARHGAP12 expression was positively correlated with higher rates of lymph node metastasis and significantly shorter OS and RFS in GC patients. Conclusion ARHGAP12 serves as a pivotal suppressor of GC metastasis. Its downregulation facilitates the epithelial-mesenchymal transition and enhances the invasive capacity of tumor cells, particularly within the Tb microenvironment.