Chromosomal characterizations of human nasal and nasopharyngeal cells immortalized by human papillomavirus type 16 DNA.

Cell lines NW-1 and NPC-N were established by transfection of human nasal and nasopharyngeal epithelial cells, respectively, with human papillomavirus type 16 (HPV-16) DNA. Additional treatment of NPC-N cells with mitomycin C gave rise to the cell line NPC-N-M. Chromosomal analysis showed that 40-47% of NW-1, NPC-N, and NPC-N-M cells had a near-tetraploid number of chromosomes and several chromosomal abnormalities. These cells showed evidence of gene amplification in the form of double minutes (dmins). In situ hybridization with HPV-16 DNA probe demonstrated that the virus was integrated at the 2q21 chromosomal region in NPC-N cells. Multiple integration sites within 1p36, 1q31-q32, 2p25, and 2q21 regions were observed in NW-1 cells. Although all of these immortal cells could grow in methylcellulose, none of them demonstrated tumorigenicity in nude mice.