The Epstein-Barr virus(EBV) is the causative agent of certain types of lymphoma and some epithelial neoplasms such as undifferentiated nasopharyngeal carcinoma, and there is recently increasing benign and malignant diseases associated with EBV.
When there is the EBV infection, the immortalization process (malignant transformation) is complex and requires several EBV proteins. Among these the EB nuclear antigen-2(EBNA 2), a specific transcriptional transactivator of viral and cellular genes, and the latent membrane protein-1 (LMP 1) play an important role of the immortalization.
The bcl 2 shows the unique functional role of blocking programmed cell death(apoptosis) independent of affecting proliferation, appears to constitute a member of a new category of oncogenes : regulators of programmed cell death.
The purpose of this study was to examine the relation between EBV and the head & neck cancers according to sites through EBV-encoded small RNA(EBER 1) in situ hybridization techniques, to examine the possibility of bcl 2 as a new category of oncogenes and to examine the relation between EBV and bcl 2 expression in the eighty two head & neck cancers (nasopharyngeal cancer 42 cases, tonsillar squamous cell carcinoma 10 cases, tonsillar lymphoma 10 cases, tongue squamous cell carcinoma 10 cases, supraglottic squamous cell carcinoma 10 cases). And we used 10 cases of normal nasopharyngeal tissue as the positive control group. For these purpose, paraffin-embedded tissues were subjected to in situ hybridization and immunohistochemistry techniques.
Following results were obtained :
1) The EBV was detected in 18(90%) out of 20 cases of nasopharyngeal undifferentiated carcinoma, 14(70%) out of 20 cases of nasopharyngeal squamous cell carcinoma, and 1(5%) out of 20 cases of tonsil cancer.
2) The LMP 1 was detected in 2(10%) out of 20 cases of nasopharyngeal undifferentiated carcinoma, in 1(5%) out of 20 cases of nasopharyngeal squamous cell carcinoma.
3) The bcl 2 was detected in 37(88.09%) out of 42 cases of nasopharyngeal cancer. 7 (35%) out of 20 cases of tonsil cancer, and 1(10%) out of 10 cases of tongue cancer.
4) The bcl 2 was detected in 29(87.88%) out of 33 cases positive for EBER 1, in 16(32.65%) out of 49 cases negative for EBER 1. And there was a strong positive signal in 25(75.76%) out of 33 cases positive for EBER 1. 6(l2.24%) out of 49 cases negative for EBER 1.
In conclusions we found that the EBV was closely related to nasopharyngeal cancer, especially undifferentiated type, and that EBER 1 in situ hybridization technique was a rapid, higher sensitive procedure and was applicable to paraffin-embedded tissues. And we thought that bcl 2 played a role of oncogenes in the head & neck cancers, especially in nasopharyngeal cancer that has been found to be closely realated to the EBV. Also there was a close relation between EBV and bcl 2 expression and the expression of bcl 2 was also thought to be induced by factors other than EBV, such as t(14 : 18) (q32 : q21) chromosomal translocation. Further studies will examine the presence of t (14, 18) chromosomal translocation in the head & neck cancers.
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