HPV-16, tobacco-specific N-nitrosamine, and N-methyl-N'-nitro-N-nitrosoguanidine in oral carcinogenesis

• Published in: Cancer research (Chicago, Ill.) Ill.), 1993-10, Vol.53 (20), p.4811-4816
• Main Authors: MYONG SOO KIM, KI-HYUK SHIN, JEONG-HWA BAEK, CHERRICK, H. M, NO-HEE PARK
• Format: Article
• Language: English
• Subjects: Base Sequence; Biological and medical sciences; Carcinogens - toxicity; Cell Division; Cell Line, Transformed; Cell Transformation, Neoplastic; Cells, Cultured; Colonic Neoplasms - genetics; DNA Primers; ErbB Receptors - genetics; Exons; Genes, myc; Genes, p53; Genes, ras; Humans; Keratinocytes - cytology; Keratinocytes - drug effects; Male; Medical sciences; Methylnitronitrosoguanidine - toxicity; Molecular Sequence Data; Mouth Neoplasms - chemically induced; Mouth Neoplasms - etiology; Mouth Neoplasms - microbiology; Mutagenesis; Nicotiana; Nitrosamines - toxicity; Oligonucleotides, Antisense; Otorhinolaryngology (head neck, general aspects and miscellaneous); Otorhinolaryngology. Stomatology; Papillomaviridae; Plants, Toxic; Polymerase Chain Reaction; Transforming Growth Factor alpha - genetics; Tumors
• ISSN: 0008-5472; 1538-7445

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.