THE CLONAL PROGRESSION IN THE NEOPLASTIC PROCESS OF NASOPHARYNGEAL CARCINOMA

The clonality of a total of 70 human nasopharyngeal carcinomas (NPC) w as analyzed using the structure of the terminal fragment of episomal E pstein-Barr virus (EBV). Thirty female samples heterozygous for the Bs tXI polymorphism of the phosphoglycerokinase (PGK) gene were analyzed using polymerase chain reaction (PCR) amplification of X-chromosome li nked PGK gene for restriction fragment length polymorphism (RFLP). All NPC samples analyzed were shown to be monoclonal, with two exceptions that were polyclonal. Clonal determination was also performed for non -cancerous cell populations: normal, and simple hyperplastic, grade I (mild) and grade II-III (severe) atypical hyperplastic epithelia. It w as found that the normal and simple hyperplastic and 3 grade I (mild) atypical hyperplastic epithelia were polyclonal, whereas the grade II- III (severe) atypical hyperplastic samples were monoclonal. The analys is of the clonality of various stages in the neoplastic process sugges ted that NPC might originate from several cells, after clonal selectio n; finally a large majority of NPC has been demonstrated to be monoclo nal, also indicating that the alteration of clonal nature might have o ccurred at a very early stage. (C) 1966 Academic Press, Inc.