Abstract 1739: Reversal of lenvatinib resistance by curcumin via EGFR signaling pathway in hepatocellular carcinoma

Abstract Background: Patients with unresectable advanced hepatocellular carcinoma (HCC) are often treated with systemic therapies, and lenvatinib is currently used as one of the first-line therapies. However, the overall response rate from lenvatinib treatment is only 24.1%, and even the patients who initially respond to this treatment often subsequently acquire therapeutic resistance to this drug. Although the mechanism of lenvatinib resistance remains unclear, recent studies have suggested the involvement of epidermal growth factor receptor (EGFR) activation, indicating that a combination of lenvatinib and EGFR inhibitors might have potential clinical applications in HCC. Curcumin is one of the most widely studied natural phytochemicals as an anti-cancer compound. Many previous studies have revealed that it also functions as a potent tyrosine kinase inhibitor that targets EGFR. Accordingly, herein we hypothesized that the anti-EFGR potential of curcumin might help overcome lenvatinib resistance in HCC. Methods: We first developed two lenvatinib-resistant cell lines and performed a series of cell line experiments, including cell proliferation, invasion, sphere formation, and apoptosis assays, to determine the impact of curcumin in overcoming this resistance. We evaluated EGFR and its downstream signaling pathway to clarify its mechanistic role in lenvatinib resistance and its subsequent reversal mediated by curcumin. Results: Among five HCC cell lines, the most sensitive and relatively insensitive cells were Huh-7 (IC50: 2.0 µM) and PLC-PRF-5 (IC50: 50.0 µM), respectively. Accordingly, we successfully established lenvatinib-resistant cells, which had significantly higher IC50 concentrations; resistant Huh-7 (IC50: 50.0 µM) and resistant PLC-PRF-5 (IC50: >100.0 µM). We noted that co-administration of curcumin with lenvatinib inhibited cell proliferation and invasion compared to lenvatinib or curcumin monotherapy. Combination therapy also promoted apoptosis in resistant Huh-7 (lenvatinib, curcumin vs. combination (9.7%, 21.8%, vs. 30.2%) and resistant PLC-PRF-5 (12.2%, 23.1%, vs. 38.2%). This combination treatment also significantly diminished the spheroid-forming ability of cancer cells via suppression of cancer stemness markers such as CD44 (p<0.01) and CD133 (p<0.01). EGFR expression was significantly upregulated in resistant cell lines, suggesting that activation of the EGFR signaling cascade might trigger lenvatinib resistance. Following treatment with a curcumin and lenvatinib combination, EGFR expression in resistant cell lines was significantly downregulated, suppressing the PI3K-AKT-mTOR axis in HCC cells. Conclusions: We provide the first evidence that curcumin could overcome lenvatinib resistance in HCC cells via suppression of EGFR and its downstream targets, which can offer a novel therapeutic strategy in HCC. Citation Format: Katsuki Miyazaki, Yuji Morine, Caiming Xu, Mitsuo Shimada, Ajay Goel. Reversal of lenvatinib resistance by curcumin via EGFR signaling pathway in hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1739.