Astaxanthin inhibits hepatocellular carcinoma by targeting USP39-mediated β-catenin stabilization through deubiquitination.

Although studies suggest that astaxanthin exerts anticancer effects through Wnt/β-catenin pathway, its therapeutic target remains unclear. The deubiquitinase USP39 may be a potential target due to its ability to regulate this pathway in hepatocellular carcinoma (HCC). This study aims to identify the role and underlying mechanism of USP39 in the anti-HCC effects of astaxanthin via Wnt/β-catenin pathway. In vitro, HepG2 and HuH7 cell lines were treated with astaxanthin, and cell proliferation was assessed using CCK-8, colony formation, and EdU assays. Western blot and real-time qPCR were used to analyze the expression of USP39, β-catenin, and Cyclin D1. Co-immunoprecipitation and ubiquitination assays were performed to confirm the interaction between USP39 and β-catenin. In vivo, HuH7 xenografts in nude mice were established to evaluate tumor growth following astaxanthin treatment. Immunohistochemistry and western blot analyses were conducted to examine the expression of USP39, β-catenin, Cyclin D1, and Ki-67 in tumor tissues. Astaxanthin treatment significantly reduced cell viability and colony formation, accompanied by decreased levels of USP39, β-catenin, and Cyclin D1, and increased phosphorylated β-catenin. Astaxanthin-induced USP39 inhibition promoted β-catenin ubiquitination and degradation, thereby blocking Wnt/β-catenin pathway activation. β-catenin overexpression partially rescued the anti-tumor effects of USP39 knockdown. Astaxanthin significantly suppressed tumor growth, inhibited the expression of USP39, β-catenin, and Cyclin D1, and reduced the proportion of Ki-67-positive cells in tumor tissues. Astaxanthin inhibits HCC through USP39-mediated ubiquitination of β-catenin, providing novel insights into its anticancer mechanism. These findings highlight the potential of targeting USP39 for HCC therapy, especially in combination with astaxanthin.