BHRF1 Enhances EBV Mediated Nasopharyngeal Carcinoma Tumorigenesis through Modulating Mitophagy Associated with Mitochondrial Membrane Permeabilization Transition.

Epstein-Barr virus (EBV) is a major contributor to nasopharyngeal carcinoma (NPC) tumorigenesis. Mitochondria have been shown to be a target for tumor viral invasion, and to mediate viral tumorigenesis. In this study, we detected that mitochondrial morphological changes in tumor tissues of NPC patients infected with EBV were accompanied by an elevated expression of BHRF1, an EBV encoded protein homologue to Bcl-2. High expression of BHRF1 in human NPC cell lines enhanced tumorigenesis and metastasis features. With BHRF1 localized to mitochondria, its expression induced cyclophlin D dependent mitochondrial membrane permeabilization transition (MMPT). The MMPT further modulated mitochondrial function, increased ROS production and activated mitophagy, leading to enhanced tumorigenesis. Altogether, our results indicated that EBV-encoded BHRF1 plays an important role in NPC tumorigenesis through regulating cyclophlin D dependent MMPT.