Emodin Induces AIF-Associated Apoptosis and Suppresses Wnt/β-Catenin Signaling in Colorectal Cancer Stem-Like Cells

Abstract

Colorectal cancer (CRC) remains a major cause of cancer-related mortality due to therapeutic resistance. Because colorectal cancer stem-like cells (CRCSCs) play a central role in tumor initiation and progression, therapeutic strategies addressing CSC-enriched populations are urgently needed. In this study, we investigated the anticancer effects of emodin, a natural anthraquinone, in CSC-enriched tumorsphere models. Emodin significantly suppressed the viability and self-renewal capacity of HCT116- and SW480-derived CSCs. It induced G0/G1 cell cycle arrest and markedly downregulated stemness-associated markers (CD44, CD133, ALDH1A1, SOX2, NANOG, and OCT4). Importantly, emodin-induced cell death was characterized by mitochondrial dysfunction, increased mitochondrial reactive oxygen species, loss of membrane potential, and nuclear translocation of apoptosis-inducing factor (AIF). This cytotoxicity was not rescued by the pan-caspase inhibitor Z-VAD-FMK, confirming caspase-independent apoptosis. Furthermore, network pharmacology and experimental validation identified GSK3β as a key target. Emodin reduced Wnt/β-catenin signaling by decreasing β-catenin stabilization and nuclear accumulation. Crucially, a rescue experiment utilizing LiCl confirmed that emodin’s suppressive effects are mechanistically dependent on the GSK3β/Wnt/β-catenin axis. Collectively, emodin suppresses CRCSC characteristics in vitro by downregulating Wnt/β-catenin signaling and inducing AIF-associated caspase-independent apoptosis, highlighting its therapeutic potential against CRC.