HMGB1 Post-Translational Modifications in Epstein–Barr Virus-Associated Nasopharyngeal Carcinoma: Current Evidence, Emerging Mechanistic Concepts, and Unresolved Questions

Nasopharyngeal carcinoma (NPC) is a geographically distinct malignancy closely associated with Epstein–Barr virus (EBV) infection and characterized by extensive epigenetic reprogramming within a highly immunosuppressive tumor microenvironment (TME). High-mobility group box 1 (HMGB1), a multifunctional chromatin-binding protein that can also act as an extracellular damage-associated molecular pattern (DAMP), has emerged as an important regulator of genome organization, transcriptional control, cellular stress responses, and immune signaling. Increased HMGB1 expression has been reported in NPC and is associated with adverse clinicopathological features and poor patient outcomes. Emerging evidence suggests that the diverse biological functions of HMGB1 are influenced by post-translational modifications (PTMs), which affect its subcellular localization, molecular interactions, and extracellular signaling functions. Through these regulatory mechanisms, HMGB1 may transition from a nuclear chromatin-associated protein to an extracellular mediator of immune and inflammatory responses. PTMs including acetylation, phosphorylation, glycosylation, oxidation, methylation, and lactylation have been implicated in regulating HMGB1 trafficking and function, although the specific roles of many of these modifications in NPC remain incompletely characterized. In this review, we summarize current evidence regarding HMGB1 PTMs and discuss their potential implications for EBV-associated NPC, with emphasis on nuclear regulation, immune crosstalk, and therapeutic response. We explicitly distinguish findings directly demonstrated in NPC from mechanistic insights derived from other malignancies and related disease models, and identify areas where proposed mechanisms remain hypothesis-generating rather than experimentally validated in NPC. By integrating current evidence with emerging mechanistic concepts, we highlight key knowledge gaps, unresolved questions, and priorities for future research. A better understanding of PTM-dependent HMGB1 regulation may facilitate the development of novel biomarker and therapeutic strategies for EBV-associated NPC.