Mechanisms of cell immortalization mediated by EB viral activation of telomerase in nasopharyngeal carcinoma.
Nasopharyngeal carcinoma (NPC) is a common cancer in Southern China and Southeast Asia. The disease is a poorly differentiated carcinoma without effective cure, and the mechanism underlying its development remains largely unknown. Of several factors identified in NPC aetiology in recent years, Epstein-Barr virus (EBV) infection has emerged to be most important. In almost all NPC cells, EBV uses several intracellular mechanisms to cause oncogenic evolution of the infected cells. One such mechanism by which EBV infection induces cellular immortalization is believed to be through the activation of telomerase, an enzyme that is normally repressed but becomes activated during cancer development. Studies show that greater than 85% of primary NPC display high telomerase activity by mechanisms involving EBV infection, consistent with the notion that EBV is commonly involved in inducing cell immortalization. More recently, different EBV proteins have been shown to activate or inhibit the human telomerase reverse transcriptase gene, by modulating intracellular signalling pathways. These findings suggest a new model with a number of challenges towards our understanding, molecular targeting and therapeutic intervention in NPC.
Liu
Jun-Ping
JP
Department of Immunology, Central Eastern Clinical School, Monash University, AMREP, Commercial Road, Prahran, Melbourne, Victoria 3181, Australia. jun-ping.liu@med.monash.edu.au
Cassar
Lucy
L
Pinto
Alex
A
Li
He
H
D002277:Carcinoma / Q000209:etiology / Q000821:virology*; D002472:Cell Transformation, Viral / Q000502:physiology*; D020031:Epstein-Barr Virus Infections / Q000150:complications; D019309:Epstein-Barr Virus Nuclear Antigens / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic; D015967:Gene Expression Regulation, Viral; D004854:Herpesvirus 4, Human / Q000472:pathogenicity*; D006801:Humans; D008954:Models, Biological; D009303:Nasopharyngeal Neoplasms / Q000209:etiology / Q000821:virology*; D019098:Telomerase / Q000378:metabolism*; D016615:Telomere / Q000473:pathology / Q000502:physiology; D014763:Viral Matrix Proteins / Q000502:physiology; D014764:Viral Proteins / Q000502:physiology; D014775:Virus Activation / Q000502:physiology*; D017735:Virus Latency
C402641:EBNA-2 protein, Human herpesvirus 4; C037662:EBV-associated membrane antigen, Epstein-Barr virus; D019309:Epstein-Barr Virus Nuclear Antigens; D014763:Viral Matrix Proteins; D014764:Viral Proteins; D019098:Telomerase