title: HPV-16, tobacco-specific N-nitrosamine, and N-methyl-N'-nitro-N-nitrosoguanidine in oral carcinogenesis.
abstract: We previously immortalized human oral keratinocytes by transfection with recombinant human papillomavirus type 16 (HPV-16) DNA and established two cell lines. These transfected cells were morphologically different from the normal counterpart, contained intact HPV-16 DNA in an integrated form, and expressed numerous viral genes. These cells contained lower levels of wild-type p53 protein and higher levels of c-myc mRNAs compared to normal cells. However, they proliferated only in keratinocyte growth medium containing a low level of calcium and were not tumorigenic in nude mice. A HPV-16-immortalized cell line was exposed to either 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone or N-methyl-N'-nitro-N-nitrosoguanidine. Four chemically transformed cell colonies were isolated. These cells proliferated well in Dulbecco's minimum essential medium containing a physiological level of calcium. They contained, similar to the immortalized counterpart, integrated HPV-16 sequences and lower levels of both wild-type p53 protein and DCC messages compared to normal cells. Among the chemically transformed cells, two colonies obtained from 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone exposure demonstrated an enhanced proliferation capacity in nude mice and transcribed a substantially higher amount of HPV-16 E6/E7, epidermal growth factor receptors, and c-myc genes compared with the immortalized counterpart. These experiments indicate that malignant transformation of oral keratinocytes can be caused by a sequential combined effect of "high risk" HPV and tobacco-related carcinogens.
authors.affiliation: School of Dentistry, University of California, Los Angeles.
authors.forename: M S
authors.initials: MS
authors.lastname: Kim
authors.forename: K H
authors.initials: KH
authors.lastname: Shin
authors.forename: J H
authors.initials: JH
authors.lastname: Baek
authors.forename: H M
authors.initials: HM
authors.lastname: Cherrick
authors.forename: N H
authors.initials: NH
authors.lastname: Park
mesh_terms: D001483:Base Sequence; D002273:Carcinogens / Q000633:toxicity*; D002455:Cell Division; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D003110:Colonic Neoplasms / Q000235:genetics; D017931:DNA Primers; D066246:ErbB Receptors / Q000235:genetics; D005091:Exons; D016259:Genes, myc; D016158:Genes, p53; D011905:Genes, ras; D006801:Humans; D015603:Keratinocytes / Q000166:cytology* / Q000187:drug effects; D008297:Male; D008769:Methylnitronitrosoguanidine / Q000633:toxicity*; D008969:Molecular Sequence Data; D009062:Mouth Neoplasms / Q000139:chemically induced / Q000209:etiology* / Q000382:microbiology; D016296:Mutagenesis; D009602:Nitrosamines / Q000633:toxicity*; D016376:Oligonucleotides, Antisense; D027383:Papillomaviridae; D010947:Plants, Toxic; D016133:Polymerase Chain Reaction; D014026:Nicotiana; D016211:Transforming Growth Factor alpha / Q000235:genetics
chemical_list: D002273:Carcinogens; D017931:DNA Primers; D009602:Nitrosamines; D016376:Oligonucleotides, Antisense; D016211:Transforming Growth Factor alpha; D008769:Methylnitronitrosoguanidine; C016583:4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone; D066246:ErbB Receptors