Cellular Senescence in Cancer: Mechanisms, Roles in Tumor Progression, and Therapeutic Implications

Cellular senescence, a state of irreversible cell cycle arrest accompanied by a senescence-associated secretory phenotype (SASP), plays dual roles in cancer biology. Initially recognized as a tumor-suppressive mechanism by halting the proliferation of damaged cells, senescence paradoxically fosters tumor progression through SASP-mediated immunosuppression and chronic inflammation. Thus, the role of senescent cells in tumors still needs to be further elucidated. Our review comprehensively examines the triggers and molecular pathways of senescence. We also summarized the characteristics and functions of senescent tumor and nontumor cells, delineating the heterogeneous tumor senescence microenvironment. Here, we highlight the functional reprogramming of senescent cells, including enhanced stemness, secretome and metabolome reprogramming, which can sustain tumorigenesis and therapeutic resistance. Furthermore, we discuss emerging therapeutic strategies, notably the “one-two punch” approach to overcome therapy resistance. By integrating recent advances in senescence-targeted therapies, our review underscores the necessity of context-specific strategies to harness senescence's tumor-suppressive effects while mitigating its protumorigenic consequences. These insights provide a roadmap for developing precision therapies and refining biomarker-driven approaches to improve cancer treatment outcomes.