A hydroxylated chalcone derivative disrupts the mitochondrial Thioredoxin-2–ROS axis to induce apoptosis in CD133+ lung cancer organoids

Resistance to conventional chemotherapy remains a major obstacle in the treatment of lung cancer and is largely driven by cancer stem-like cells (CSCs). Here, we investigated the molecular mechanisms underlying the anticancer activity of a hydroxylated chalcone derivative (UR-2) using CD133 + lung cancer organoid and xenograft models. Quantitative proteomic profiling identified mitochondrial Thioredoxin-2 (TRX2), encoded by the TXN2 gene, as a key regulator of UR-2-induced redox signaling. Functional studies demonstrated that UR-2 preferentially inhibited the growth, self-renewal, and clonogenic capacity of CD133 + lung cancer organoids while exerting minimal effects on CD133 − cells. Mechanistically, UR-2 reduced TXN2 mRNA and TRX2 protein expression, resulting in intracellular reactive oxygen species (ROS) accumulation, mitochondrial membrane depolarization, cytochrome c release, Bax activation, and Caspase-3-dependent apoptosis. UR-2 was also associated with decreased β-catenin expression, suggesting attenuation of CSC-associated stemness signaling. Importantly, restoration of TRX2 signaling by 17β-estradiol (E2) or ROS scavenging with N-acetyl-L-cysteine (NAC) significantly attenuated UR-2-induced ROS accumulation, mitochondrial dysfunction, apoptosis, and β-catenin downregulation, supporting disruption of the TXN2/TRX2-mediated mitochondrial redox pathway as a key upstream event underlying UR-2 cytotoxicity. Furthermore, UR-2 exhibited greater anti-tumor activity than 5-fluorouracil and cisplatin in CD133 + organoids and significantly suppressed tumor growth in the corresponding xenograft models, accompanied by a reduced abundance of CD133-positive cells and a shift in the BCL-2/Bax balance toward a pro-apoptotic state. Collectively, these findings identify the TXN2/TRX2-ROS axis as a critical regulator of CSC survival and suggest that UR-2 suppresses stemness while promoting mitochondrial apoptosis through disruption of redox homeostasis, highlighting its therapeutic potential for targeting chemoresistant lung cancer.