Niclosamide Revitalizes Sorafenib through Insulin-like Growth Factor 1 Receptor (IGF-1R)/Stemness and Metabolic Changes in Hepatocellular Carcinoma

SIMPLE SUMMARY: Sorafenib resistance is the major challenge for the unsatisfactory response to targeted therapies in advanced hepatocellular carcinoma (HCC). Combination therapy may overcome the obstacle and is an increasingly acceptable strategy. In this study, we demonstrate that niclosamide can increase sorafenib sensitivity in sorafenib-resistant HCC cells/organoids through the regulation of insulin-like growth factor 1 receptor (IGF-1R)/p-IGF-1R/stemness and metabolic changes. A combination of sorafenib and niclosamide can yield a synergistic combination index (CI) for sorafenib-resistant HCC cells that decrease the expressions of IGF-1R/p-IGF-1R/OCT4, attenuate stemness-related properties, downregulate the glycolysis-associated gene expressions, and reduce the mitochondrial membrane potential in vitro, and decrease tumor size and tumor volume resulting from apoptosis in vivo. These findings may highlight a practical clinical strategy for repurposing niclosamide for enhancing sorafenib sensitivity in HCC. ABSTRACT: Sorafenib is the first approved systemic targeting agent for advanced HCC; however, when used alone, drug resistance can result in considerably reduced efficacy. Here, we demonstrate that niclosamide, an antihelminthic agent approved by the US Food and Drug Administration, can be repurposed to increase sorafenib sensitivity in sorafenib-resistant HCC cells. We generated sorafenib-resistant HCC cell lines (HepG2215_R and Hep3B_R) with elevated IGF-1R levels and strong properties in terms of stemness and epithelial–mesenchymal transition. Niclosamide was found to increase sorafenib sensitivity effectively in both cell lines and their organoids. The underlying mechanism involves the modulation of cancer stemness, IGF-1R/p-IGF1R/OCT4, and metabolic changes. The combination of sorafenib and niclosamide, but not linsitinib, effectively suppressed the IGF-1R/OCT4 expressions, yielded a synergistic combination index (CI), and attenuated stemness-related properties such as secondary tumor sphere formation and cell migration in sorafenib-resistant HCC cells. Notably, niclosamide significantly suppressed the sorafenib-induced IGF-1R phosphorylation prompted by IGF-1 treatment. Niclosamide effectively downregulated the sorafenib-induced gene expression associated with glycolysis (GLUT1, HK2, LDHA, and PEPCK), stemness (OCT4), and drug resistance (ABCG2) and enhanced the ability of sorafenib to reduce the mitochondrial membrane potential in vitro. The synergistic effect of a combination of niclosamide and sorafenib in vivo was further demonstrated by the decreased tumor size and tumor volume resulting from apoptosis regulation. Our results suggest that niclosamide can enhance sorafenib sensitivity in sorafenib-resistant HCC cells through IGF-1R/stemness regulation and metabolic changes. Our findings highlight a practical clinical strategy for enhancing sorafenib sensitivity in HCC.