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

Abstract

It was reported that polyphenols extracted from Korean Artemisia annua 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.