CD44: A Key Regulator of Iron Metabolism, Redox Balance, and Therapeutic Resistance in Cancer Stem Cells

Abstract CD44, a multifunctional cell surface protein, has emerged as a pivotal regulator in cancer stem cell (CSC) biology, orchestrating processes such as stemness, metabolic reprogramming, and therapeutic resistance. Recent studies have identified a critical role of CD44 in ferroptosis resistance by stabilizing SLC7A11 (xCT), a key component of the antioxidant defense system, enabling CSCs to evade oxidative stress and sustain tumorigenic potential. Additionally, CD44 regulates intracellular iron metabolism and redox balance, further supporting CSC survival and adaptation to stressful microenvironments. Therapeutic strategies targeting CD44, including ferroptosis inducers and combination therapies, have shown significant potential in preclinical and early clinical settings. Innovations such as CD44-mediated nanocarriers and metabolic inhibitors present novel opportunities to disrupt CSC-associated resistance mechanisms. Furthermore, the dynamic plasticity of CD44 isoforms governed by transcriptional, post-transcriptional, and epigenetic regulation underscores the importance of context-specific therapeutic approaches. This review highlights the multifaceted roles of CD44 in CSC biology, focusing on its contribution to ferroptosis resistance, iron metabolism, and redox regulation. Targeting CD44 offers a promising avenue for overcoming therapeutic resistance and improving the outcomes of refractory cancers. Future studies are needed to refine these strategies and enable their clinical translation.