Tetraarsenic Hexoxide Enhanced the Anticancer Effects of Artemisia annua L. Polyphenols by Inducing Autophagic Cell Death and Apoptosis in Oxalplatin-Resistant HCT116 Colorectal Cancer Cells

It was reported that polyphenols extracted from Korean <i>Artemisia annua</i> L. (pKAL) have higher anticancer effects in oxaliplatin-resistant (OxPt-R) HCT116 cells than in HCT116 cells. In this study, it was tested whether and how As₄O₆ enhances anticancer effects of pKAL in HCT116 and HCT116-OxPt-R colorectal cancer cells. The CCK-8 assay, phase-contrast microscopy, and colony formation assay revealed that As₄O₆ enhanced anticancer effects of pKAL, with induction of nuclear deformity and intracytoplasmic vesicle formation in both cells. Western blot analysis revealed that co-treatment with As₄O₆ and pKAL significantly decreased the expression of NF-kB, EGFR, cyclin D1, CD44, and β-catenin, and upregulated the expression of p62 and LC3B in both cells. It also induced the activation of caspase-8 and γ-H2AX and the cleavage of β-catenin, PARP1, lamin A/C, and p62. These phenomena were inhibited by wortmannin, and further suppressed by co-treatment of wortmannin with an ROS inhibitor, N-acetyl cysteine. This study suggests that As₄O₆ enhanced the anticancer effects of pKAL by inducing autophagic cell death accompanied by apoptosis in both parental HCT116 and HCT116-OxPt-R cells. It also suggests that ROS generation and the downregulation of AKT, NF-κB p65, cyclin D1, EGFR, and β-catenin may play an important role in the As₄O₆-enhanced anticancer effect of pKAL.