LMP1 mediates tumorigenesis through persistent epigenetic modifications and PGC1β upregulation

Area of Science:

• Oncology
• Virology
• Molecular Biology

Background:

• Latent membrane protein 1 (LMP1) from Epstein-Barr virus (EBV) is an oncogene, but its precise role in tumorigenesis is unclear.
• LMP1 is thought to promote cancer by upregulating peroxisome proliferator-activated receptor-γ coactivator-1β (PGC1β).

Purpose of the Study:

• To investigate how transient EBV/LMP1 exposure leads to persistent PGC1β expression and tumorigenesis.
• To explore the role of mitochondrial function modification in this process.

Main Methods:

• Luciferase reporter assays, chromatin immunoprecipitation, and DNA mutation techniques were used to assess PGC1β-mediated dynamin-related protein 1 (DRP1) expression.
• In vitro assays evaluated gene expression, oxidative stress, mitochondrial function, and cell proliferation.
• In vivo xenograft mouse models assessed tumor growth and survival.

Main Results:

• LMP1 knockdown did not affect PGC1β expression or proliferation in EBV-positive cells.
• PGC1β regulates DRP1 expression, modulating mitochondrial fission.
• Transient EBV/LMP1 exposure induced persistent epigenetic changes and PGC1β upregulation in hematopoietic stem cells, enhancing mitochondrial function and proliferation.
• In vivo studies showed increased tumor growth and reduced survival.

Conclusions:

• PGC1β expression and cell proliferation are independent of LMP1 in EBV-positive cells.
• PGC1β influences mitochondrial fission via DRP1 regulation.
• Transient EBV/LMP1 exposure can trigger tumor growth through persistent epigenetic changes and PGC1β upregulation, explaining PGC1β overexpression in EBV-negative lymphomas.