CLK2 Regulates the KEAP1/NRF2 and p53 Pathways to Suppress Ferroptosis in Colorectal Cancer.

UNLABELLED: Ferroptosis, a form of regulated cell death driven by iron-dependent lipid peroxidation, plays a crucial role in colorectal cancer progression and therapeutic response. The nuclear factor erythroid 2-related factor 2 (NRF2) pathway is one of the critical axes in ferroptosis regulation, which governs oxidative stress resistance and iron homeostasis through its downstream targets, including heme oxygenase 1 (HMOX1), solute carrier family 7 member 11 (SLC7A11), and others. However, HMOX1 and SLC7A11 exhibit contrasting roles in ferroptosis, with HMOX1 promoting ferroptosis via iron accumulation and lipid peroxidation, whereas SLC7A11 inhibits ferroptosis by enhancing antioxidant defenses. In this study, we identified CLK2 as a key regulator of the delicate balance of the opposing effects of HMOX1 and SLC7A11. CDC-like kinase 2 (CLK2) stabilized Kelch-like ECH-associated protein 1 (KEAP1) to suppress NRF2 activity, resulting in the downregulation of HMOX1 and SLC7A11. Simultaneously, CLK2 downregulated p53, thereby relieving p53-mediated repression of SLC7A11. The dual regulation by CLK2 disrupted the balance between HMOX1 and SLC7A11, leading to excessive activation of HMOX1 in the absence of CLK2, ultimately sensitizing colorectal cancer cells to ferroptosis. Additionally, CLK2 promoted colorectal cancer proliferation and tumorigenesis in patient-derived organoids, cell lines, and mouse models. Furthermore, combining the ferroptosis inducer erastin with oxaliplatin significantly enhanced antitumor efficacy in CLK2-deficient xenograft models. Together, this study establishes CLK2 as a critical inhibitor of ferroptosis via the KEAP1/NRF2/HMOX1 and p53/SLC7A11 axes, supporting its potential as a therapeutic target for colorectal cancer.

SIGNIFICANCE: CLK2 blocks ferroptosis in colorectal cancer by regulating the HMOX1 and SLC7A11 balance through the KEAP1/NRF2 axis and p53 pathways, providing a strong rationale for targeting CLK2 to treat colon cancer.