Osteopontin‐integrin αvβ3 axis is crucial for 5‐fluorouracil resistance in oral squamous cell carcinoma

Clinical applications of a chemotherapeutic agent, 5-fluorouracil (5-FU) in oral squamous cell carcinoma (OSCC) have been limited because of drug resistance. This study aimed to identify novel mechanisms of 5-FU resistance. Here we found increased osteopontin (OPN) gene expression in OSCC tissues with resistance to 5-FU-based chemoradiotherapy. OPN overexpression in OSCC cells led to 5-FU resistance and abrogated the prosurvival effect of the drug in a mouse xenograft model. OPN-induced 5-FU resistance required integrin αvβ3. Targeting integrin αvβ3 reversed the resistance in a 5-FU-resistant clone highly expressing OPN. Our data suggest that the OPN-integrin αvβ3 axis is crucial for 5-FU resistance in OSCC.