Tumorigenicity of nasopharyngeal carcinoma hybrid cell line

The spontaneous production of Epstein-Barr virus (EBV) and tumorigenicity in the BALB/c mutant nude mouse were studied with the use of the following 4 cell lines derived from the human nasopharynx: a) Ad-AH, an 8-azahypoxanthine-resistant epithelioid cell line; b) A2L, an EBV-carrying lymphoblastoid cell line; c) A2L/AH, an EBV-carrying epithelioid hybrid cell line established by fusion of Ad-AH cells with A2L cells; and d) NPC-KT, an EBV-carrying epithelioid hybrid cell line established by fusion of Ad-AH cells with nasopharyngeal carcinoma (NPC) primary culture cells. The NPC-KT hybrid cell line was the only cell line to produce EBV antigens of the lytic cycle and virus particles. Cloning efficiency in agarose was clearly related to tumorigenicity in nude mice. Especially high, frequent tumor formation was observed in the heterotransplantation of NPC-KT hybrid cells that presented poorly differentiated carcinoma, and the tumor cells were positive for EBV-associated nuclear antigen. These NPC-KT hybrid cells maintained the characteristics of a histologic type of NPC tumor cells. Thus experimental systems of NPC were established in vitro and in vivo by the application of NPC-KT hybrid cells to NPC model cells.