Loss of an XhoI-site within N-terminal region of Epstein-Barr virus LMP1 gene in nasopharyngeal carcinoma.
OBJECTIVE
It is well known that Epstein-Barr virus(EBV) LMP1 gene is involved in nasopharyngeal carcinogenesis. This research was designed to investigate the loss of an Xho I-site within the N-terminus of Epstein-Barr virus(EBV) latent membrane protein 1(LMP1) gene isolated from nasopharyngeal carcinoma (NPC) in Guangdong for further understanding the sequence variation of LMP1 gene involved in carcinogenesis.


METHODS
Sixty-three fresh nasopharyngeal biopsies taken from the patients with nasopharyngeal carcinoma were collected in Cancer Center of Sun Yat-sen University. The peripheral blood mononuclear cells (PBMCs) obtained from 10 healthy EBV carriers were as control. The QIAamp DNA Mini Kits were used for extracting the DNA of biopsies and PBMCs. The N-terminus of EBV LMP1 gene was amplified using nested polymerase chain reaction (PCR) and then followed by Xho I enzyme digestion. Bidirectional solid-phase sequencing of the PCR products was performed using four-colored fluorescence terminator sequencing method.


RESULTS
No loss of an Xho I-site within N-terminus of EBV LMP1 gene (wt-Xho I) was detected in PBMCs of all 10 carriers. The loss of an Xho I-site (Xho I-loss) was demonstrated in 50 cases (50/63, 79.36%) and the partial loss was demonstrated in 4 cases (4/63, 6.35%). The loss of an Xho I-site was not found in 9 cases (9/63, 14.29%). Besides loss of an Xho I-site (nt:169423-169428; GAGCTC --> GATCTC), 4 additional missense point mutations were found.


CONCLUSIONS
According to the results obtained from this investigation, the PBMCs of 10 EBV carriers residing in Guangdong merely contain EBV variant with wt-Xho I. On the contrary, the EBV variant with XhoI-loss becomes the predominant variant detected in NPC tissues. So, the genomic variation within N-terminus (loss of an Xho I-site and other missense point mutations) of EBV LMP1 gene might be developed in the process of nasopharyngeal carcinogenesis.
Lin
Su-Xia
SX
Department of Pathology, Cancer Center, Sun Yat-sen University, Guangzhou, PR China.
Zong
Yong-Sheng
YS
Wu
Qiu-Liang
QL
Han
An-Jia
AJ
Liang
Ying-Jie
YJ
D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D009303:Nasopharyngeal Neoplasms / Q000821:virology*; D014763:Viral Matrix Proteins / Q000235:genetics*
C037662:EBV-associated membrane antigen, Epstein-Barr virus; D014763:Viral Matrix Proteins; C034510:CTCGAG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific