Advancement of studying the biological characteristics of nasopharyngeal carcinogenesis

This review is to summarize the main achievements of studying the biological characteristics of nasopharyngeal carcinogenesis performed by the authorsresearch team and the recent advancement in this field during the past 5 years as well as to explain the authorsviewpoints concerning the nasopharyngeal carcinogenesis. In order to study the nasopharyngeal carcinogenesis,more than 20 000 nasopharyngeal carcinoma biopsies and more than 600 nasopharyngeal biopsies of Epstein Barr virus seropositive persons who had been got follow up over 12 years, were collected. In addition, nude mice and cell lines were also to be utilized. Besides histopathological staining, methods of molecular biology, including in situ hybridization, PCR etc. were applied. Up to date,26 papers concerning this subject had been formally published in the medico biological journals at home and abroad. The results and conclusions were as follows. (1)The squamous metaplasia, epithelial dysplasia, carcinoma in situ and microinvasive carcinoma are the morphogenetic sequence found in nasopharyngeal carcinogenesis. (2)This morphogenetic sequence is frequently observed in a restricted area of nasopharyngeal mucosal epithelium, representing as an appearance of field carcinogenesis. (3)EB virus may play a critical role in nasopharyngeal carcinogenesis, since EB virus DNA and small RNAs could be detected in epithelial dysplasia first and several viral encoded products, especially LMP1, might be expressed in dysplasia, carcinoma in situ and microinvasive carcinoma. (4)The multigenic mechanisms, including interactions between EB viral genes encoded products and the products abnormally expressed step by step from genes related to cell cycle regulation, are the molecular events involved in nasopharyngeal carcinogenesis. (5)The cellular immunity of individuals should also be considered as an important factor influencing nasopharyngeal carcinogenesis, because EB virus specific cytotoxic T lymphocytes could not only be observed in carcinoma nests but also detected in peripheral blood.