Objective: The latent membrane protein-1 (LMP-1) is an Epstein-Barr virus (EBV)-transforming protein expressed in nasopharyngeal carcinoma (NPC). A 30-bp deletion in the LMP-1 oncogene has been described in NPC patients from Asia. The purpose of this study was to evaluate the association between NPC and such an EBV deletion in Caucasian patients.
Material and methods: Twenty-seven patients with a diagnosis of NPC were selected. Most of the NPCs were classified as Stages III and IV using the International Union Against Cancer system. Formalin-fixed, paraffin-embedded NPC specimens were found for these cases. Hematoxylin-eosin slides were reviewed and survival analysis was done using the log-rank method. In situ hybridization for EBV-encoded non-polyadenylated RNAs and expression of LMP-1 by means of immunohistochemistry was also performed. Polymerase chain reaction for LMP-1 oncogene analysis was performed to detect the presence of a 30-bp deletion in NPC specimens and EBV-related controls
Results: The 30-bp deletion was identified in 67% of NPC cases and in 30% of controls, a statistically significant difference (p = 0.01, chi2 test). LMP-1 deletion was not statistically associated with a worse prognosis in NPC patients (5-year survival: 33% in wild-LMP-1 strains vs 24% in deleted-LMP-1 strains; p = 0.053, log-rank test).
Conclusion: A 30-bp deletion in the LMP-1 oncogene is present in more than half of Caucasian NPC cases EBV carrying partial deletions in the LMP-1 oncogene may play a role in the pathogenesis of NPC in Caucasian patients.