Cancer-associated fibroblasts confer cisplatin resistance of tongue cancer via autophagy activation

Cancer-associated fibroblasts (CAFs) play important roles in carcinogenesis and progression of tongue squamous cell carcinoma (TSCC). However, effect of CAFs on chemotherapy resistance of TSCC remains largely obscure. Here, we cultured the matched primary CAFs and normal fibroblasts (NFs) pairs and detected their roles in cisplatin sensitivity of TSCC, as well as autophagy-related protein LC3 and Beclin1 expressions. During exposure to cisplatin, TSCC with CAFs group exhibited significantly increased cell viability and IC50, but reduced apoptosis than that with NFs group. Meanwhile, cisplatin increased the LC3-II and Beclin1 levels of those TSCC co-cultured with CAFs. Activation of cisplatin-induced autophagic flux was inhibited by CQ, which can accumulate LC3-II protein and increase punctate distribution of LC3 localization. Beclin1 siRNA also decreased the cisplatin-induced autophagy. Both CQ and Beclin1 siRNA increased cisplatin-induced apoptosis but inhibited viability of TSCC co-cultured with CAFs. In vivo, combination of cisplatin and CQ significantly inhibited the growth of xenografted tumors than cisplatin alone. Taken together, our findings highlight the important role of CAFs in cisplatin resistance of tongue cancer via autophagy activation, suggesting that inhibition of autophagy could be an optimal strategy for chemoresistance of TSCC.