Epstein-Barr Virus Enhances Cancer-Specific Aberrant Splicing of TSG101 Pre-mRNA

Tumor viruses gain control of cellular functions when they infect and transform host cells. Alternative splicing is one of the cellular processes exploited by tumor viruses to benefit viral replication and support oncogenesis. Epstein-Barr virus (EBV) participates in a number of cancers, as reported mostly in nasopharyngeal carcinoma (NPC) and Burkitt lymphoma (BL). Using RT-nested-PCR and Northern blot analysis in NPC and BL cells, here we demonstrate that EBV promotes specific alternative splicing of TSG101 pre-mRNA, which generates the TSG101 increment 154-1054 variant though the agency of its viral proteins, such as EBNA-1, Zta and Rta. The level of TSG101 increment 154-1054 is particularly enhanced upon EBV entry into the lytic cycle, increasing protein stability of TSG101 and causing the cumulative synthesis of EBV late lytic proteins, such as VCA and gp350/220. TSG101 increment 154-1054-mediated production of VCA and gp350/220 is blocked by the overexpression of a translational mutant of TSG101 increment 154-1054 or by the depletion of full-length TSG101, which is consistent with the known role of the TSG101 increment 154-1054 protein in stabilizing the TSG101 protein. NPC patients whose tumor tissues express TSG101 increment 154-1054 have high serum levels of anti-VCA antibodies and high levels of viral DNA in their tumors. Our findings highlight the functional importance of TSG101 increment 154-1054 in allowing full completion of the EBV lytic cycle to produce viral particles. We propose that targeting EBV-induced TSG101 alternative splicing has broad potential as a therapeutic to treat EBV-associated malignancies.

Automated summary

This study reveals that Epstein-Barr virus (EBV) can promote specific alternative splicing of TSG101 pre-mRNA, generating a variant called TSG101 increment 154-1054, which enhances the EBV lytic cycle and the synthesis of viral proteins. The expression of TSG101 increment 154-1054 in NPC tumor tissues is associated with high levels of serum antibodies and viral DNA. Targeting EBV-induced TSG101 alternative splicing could be a potential therapeutic approach for EBV-associated malignancies.