HMGB3: A pivotal orchestrator of therapy resistance and cancer stemness in human malignancies (Review)

High mobility group box 3 (HMGB3) acts as an essential participator in fundamental biological processes, including transcriptional regulation, chromatin remodeling and DNA repair. HMGB3 is highly expressed and functionally essential during embryonic development, particularly in the hematopoietic and nervous systems, but it is significantly downregulated or silenced in most normal adult tissues. Its aberrant upregulation has been revealed in numerous human malignancies, such as leukemia, as well as breast, bladder, colorectal and gastric cancer, and its expression levels have been established to be closely associated with poor prognosis of specific patients. Accordingly, the present review systematically explores the central roles of HMGB3 in mediating resistance to cancer therapy. This review focuses on its multifaceted mechanisms of maintaining cancer stemness, enhancing DNA damage repair, modulating cell death pathways and remodeling the tumor microenvironment, thereby contributing to the resistance to chemotherapy, radiotherapy, targeted therapy and immunotherapy collectively. HMGB3 can be accepted as a key target in the development of highly promising therapeutic strategies, given its pivotal involvement in multidrug resistance, which may offer novel avenues for overcoming clinical treatment resistance and improving patient outcomes.