Chemical transformation of human embryonic nasopharyngeal epithelial cells in vitro.

The association of Epstein-Barr virus (EBV) with poorly differentiated carcinoma of the nasopharynx is well known; however, certain environmental factors, such as nitrosamines, are also important for the development of this cancer (Ho, 1975). N,N'-Dinitrosopiperazine (DNPZ) can induce nasopharyngeal carcinoma in rats and increased sister chromatid exchange frequency in human embryonic nasopharyngeal epithelial (HENE) cells. We have now demonstrated the transformation by DNPZ of HENE cells, which had a prolonged life span, anchorage-independent growth, chromosomal aberrations, tumorigenicity and morphological and ultrastructural alterations. These transformed cells might derive from the columnar epithelium of the nasopharynx, as indicated by the positive histochemical reaction with CAM 5.2 antikeratin antibody. Negative results in an immunofluorescence test for EBV nuclear antigen and Southern hybridization for EBV DNA rule out the participation of this virus in the neoplastic transformation of HENE cells by DNPZ.