| Summary: | 博士 === 國立臺灣大學 === 病理學研究所 === 81 === Nasopharyngeal carcinoma (NPC) is one of the most common head
and neck malignancies in Taiwan. The pathogenesis of NPC
remains unclear. Epastein-Barr virus (EBV) is the most
important contributing factor of NPC. In order to better
understand the role of EBV in pathogenesis of NPC, we have
attempted to char- acterize viral infection and identify the
viral genes expressed in 60 cases of NPC. The results showed
EBV genome is only present in the tumor cells of NPC but not
the infiltrating lymphocytes. The tumor was clonal expansion
from one EBV-containing cells and had episomal form EBV DNA and
most of them also had linear form DNA, indica- ting presence of
latent EBV in all NPC, and with viral replica- tion in most
cases. The EBV typing study revealed EBV-1 only. The EBV gene
expression was studied in 10 cases of NPC by reverse
transcriptase-polymerase chain reaction (RT-PCR) and in situ
hybridization. Six EBV latent genes and the immediate early
gene-BamHI Z leftward frame 1 (BZLF1) were checked. An An other
EBV latent small RNA, EBER1, was detected in 48 NPC cases by in
situ hybridization. The results revealed all NPCs had EBNA1 and
LMP2A, LMP1 and BZLF1 were detected in 8 cases each, LMP2B in 6
cases, and BARF0 in 9 cases. Three cases had trace amount of
EBNA2 message. All studied NPC cases containing EBER1 message
in tumor cells and the infiltrating lymphocytes were
consistently negative. The EBV-related antigens was detected by
immunocytochemistry using different antibodies. The results
showed only 21 cases (36.2%) of 58 NPCs were LMP1 protein
positive. The other EBV- related antigens were all negative.
The staining pattern of LMP1 in NPC tumor cells was diffusely
distributed in cytoplasm with no cytoplasmic aggregate as seen
in lymphoblastoid cells.
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