Rewiring of the Apoptotic Rheostat in HTLV-1 Infection and Adult T-Cell Leukemia/Lymphoma

Human T-cell leukemia virus type 1 (HTLV-1) is the etiological agent of an aggressive malignancy of mature T-cells termed adult T-cell leukemia/lymphoma (ATLL), as well as a spectrum of chronic inflammatory diseases. A defining feature of HTLV-1 infection is a profound dysregulation of apoptotic pathways, which is a key determinant of long-term viral persistence and favors malignant transformation. This review describes the mechanisms through which HTLV-1 gene products, including Tax and HBZ, reprogram host-cell signaling controlling the "apoptotic rheostat", an integrated network connecting redox metabolism, and response to apoptotic cues and immune pressure. We also highlight emerging therapeutic strategies to restore sensitivity to apoptosis, including BH3-mimetic drugs and rational combination approaches. Deciphering how HTLV-1 reconfigures the apoptotic network provides a conceptual and therapeutic framework for targeting death pathway vulnerabilities in ATLL and potentially other hematological neoplasms.