Quercetin represses cholesterol metabolism and mitigates resistance to cisplatin in oral squamous cell carcinoma by regulating AGR2/AKT/SREBP2 axis.

Purpose: This study aimed to explore the effects of quercetin on cholesterol metabolism and cisplatin sensitivity in oral squamous cell carcinoma (OSCC) cell line (CAL27) and investigate the potential molecular mechanisms.

Methods: CAL27 cells were exposed to quercetin or cisplatin after upregulation or downregulation of AGR2. The expression of proteins and genes associated with cholesterol metabolism were assessed. The levels of cholesterol and LDL were also measured, and the cisplatin sensitivity of CAL27 cells was analyzed.

Results: RNA high-throughput sequencing revealed that after treatment with quercetin, the expression of AGR2 was significantly reduced in cisplatin-resistant CAL27 cells (CAL-27R), which was associated with lipid metabolism. AGR2 deletion ameliorated but its overexpression exacerbated cisplatin resistance and cholesterol metabolism, evidenced by changes in SQLE, HMGCS, LDLR, and n-SREBP2 expression and cholesterol and LDL levels. Moreover, AGR2 promoted cisplatin resistance by activating the AKT signaling pathway and enhancing SREBP2-mediated cholesterol metabolism. Quercetin increased cisplatin sensitivity by repressing cholesterol metabolism but suppressed the AGR2/AKT/SREBP2 signaling pathway in a concentration-dependent manner. These effects were partly reversed by AGR2 overexpression and AKT activation.

Conclusion: Our findings demonstrated that quercetin inhibits cholesterol metabolism and cisplatin resistance in CAL27 cells by modulating the AGR2/AKT/SREBP2 axis.