Targeted disruption of the epidermal growth factor receptor inhibits development of papillomas and carcinomas from human papillomavirus-immortalized keratinocytes.
The epidermal growth factor receptor (EGF-R) is frequently overexpressed in human papillomavirus (HPV)-associated dysplasias and carcinomas, implying that it is important for the progression of keratinocytes to malignancy. We used mice with a targeted disruption of the EGF-R gene to directly examine its role in cell immortalization and tumor development. Epidermal keratinocytes were cultured from EGF-R knockout, heterozygous, and wild-type mice, infected with retroviruses encoding HPV-16 E6 and E7 oncogenes, and grafted to nude mice. E6/E7 induced immortalization of EGF-R wild-type cells 5-fold more efficiently than null cells. Immortal EGF-R null cells grew more slowly, achieved a lower saturation density, and were more sensitive to apoptosis than the immortalized wild-type or heterozygous cells. Analyses using cDNA expression arrays showed that EGF-R null cells expressed increased levels of RNAs encoding p21waf and insulin-like growth factor-binding protein-2. EGF-R-positive immortal keratinocytes formed papillomas in 17% (15 of 90) of skin grafts, and seven grafts progressed to squamous carcinoma after 6-12 months. EGF-R null keratinocytes did not form papillomas, but 1 of 96 grafts progressed to a squamous carcinoma after 1 year. However, treatment with the tumor promoter 12-O-tetradecanoylphorbol-13-acetate induced tumors in 18 and 35% of grafts containing EGF-R null or EGF-R-positive cells, respectively. Transduction with an activated v-Ha-ras gene, which signals downstream of the EGF-R, induced rapidly growing carcinomas in all grafts regardless of EGF-R genotype. These results directly show that the EGF-R is important, but not essential, for immortalization by HPV and for progression of immortal cells to papillomas and carcinomas.
Woodworth
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Laboratory of Cellular Carcinogenesis and Tumor Promotion, National Cancer Institute, Bethesda, Maryland 20892-4255, USA. woodworth@clarkson.edu
Gaiotti
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Michael
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Hansen
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Nees
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D000818:Animals; D002273:Carcinogens; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced / Q000517:prevention & control* / Q000821:virology; D002461:Cell Line, Transformed; D002472:Cell Transformation, Viral; D003043:Cocarcinogenesis; D018450:Disease Progression; D066246:ErbB Receptors / Q000235:genetics / Q000502:physiology*; D015870:Gene Expression; D011905:Genes, ras / Q000235:genetics; D005838:Genotype; D006801:Humans; D015603:Keratinocytes / Q000473:pathology / Q000637:transplantation / Q000821:virology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009154:Mutation; D009856:Oncogene Proteins, Viral / Q000235:genetics; D010212:Papilloma / Q000139:chemically induced / Q000517:prevention & control* / Q000821:virology; D027383:Papillomaviridae / Q000235:genetics*; D050725:Papillomavirus E7 Proteins; D012097:Repressor Proteins; D012878:Skin Neoplasms / Q000517:prevention & control* / Q000821:virology; D013755:Tetradecanoylphorbol Acetate
D002273:Carcinogens; C068651:E6 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D012097:Repressor Proteins; C059731:oncogene protein E7, Human papillomavirus type 16; D066246:ErbB Receptors; D013755:Tetradecanoylphorbol Acetate