| Abstract: |
Chemoresistance is the major cause of gastric adenocarcinoma (GA) treatment failure. The mechanisms underlying chemoresistance remain incompletely understood. Here, we sought to identify genes differentially expressed between chemoresistant and chemosensitive GA and to validate the function of the top hit. High-throughput RNA sequencing was performed to detect chemoresistance-related genes. The function of the only gene overexpressed in both chemoresistant tumors and tumor tissue relative to normal gastric epithelia, forkhead box C1 (FOXC1), was examined in GA cells, mouse xenograft models, and patient-derived organoid (PDO) systems, focusing on cancer stem-like cell (CSC) phenotypes, metastasis, and chemoresistance. FOXC1 was expressed at significantly higher levels in GA patient tumors that were resistant to chemotherapy, and high FOXC1 tumor expression was significantly correlated with poor survival among patients undergoing resection (p = 0.011). FOXC1 activity was significantly higher in spheroid-forming or CD44+ GA CSCs than in unselected cells. Inhibition of FOXC1 decreased the expression of CD44 and Sox2, decreased spheroid size by 78%–82%, and decreased spheroid number (>100 μm) by 75%–86%. GA CSC chemotherapy resistance was reversed with FOXC1 inhibition in vitro and in vivo and in PDOs. Mechanistic studies indicated that FOXC1 acts via the hedgehog and epithelial-to-mesenchymal transition (EMT) pathways. Our results imply that FOXC1 mediates the CSC phenotypes, metastasis, and chemotherapy resistance of GA through hedgehog and EMT signaling. FOXC1 inhibitors may thus represent a novel strategy to overcome chemoresistance. © 2021 The American Society of Gene and Cell Therapy |
