v-Ha-ras-induced mouse skin papillomas exhibit aberrant expression of keratin K13 as do their 7,12-dimethylbenz[a]anthracene/12-O-tetradecanoylphorbol-13-acetate -induced analogues.
Introduction of the v-Ha-ras gene into primary epidermal keratinocytes, followed by grafting of these cells to animals, leads to the formation of benign epidermal tumors that resemble papillomas induced chemically by a two-stage carcinogenesis protocol. In this study, we investigated v-Ha-ras-induced papillomas for aberrant expression of type I keratin K13, previously described in 7,12-dimethylbenz[a]anthracene/12-O-tetradecanoylphorbol-13- acetate (DMBA/TPA)-induced mouse epidermal tumors. Papillomas produced from three independent infection series were removed 3 wk after grafting concomitant with control grafts originating from mock-, neo-, and v-fos-infected primary keratinocytes. Combined analysis of the grafts by western blotting of extracted keratins and immunofluorescence studies of frozen sections with a K13-monospecific antibody revealed K13 expression in all v-Ha-ras-induced papillomas and absence of this keratin in all control grafts. K13-positive cells in papillomas were restricted to the suprabasal cell layers of the lesions and, at this stage of papilloma development, occurred as foci of varying extensions. Analysis of genomic DNA from v-Ha-ras-induced papillomas for the methylation state of a CpG dinucleotide in the distant promoter region of the K13 gene revealed the occurrence of unmethylated DNA copies that were generated at the expense of methylated DNA copies ubiquitously present in normal epidermis. The ratio of unmethylated to methylated DNA copies correlated with the extent of suprabasal K13 protein expression. Thus, all features of aberrant K13 expression previously described in DMBA/TPA-induced papillomas were shared by v-Ha-ras-induced papillomas.
Sutter
C
C
German Cancer Research Center, Institute of Biochemistry, Heidelberg, Federal Republic of Germany.
Strickland
J E
JE
Welty
D J
DJ
Yuspa
S H
SH
Winter
H
H
Schweizer
J
J
D015127:9,10-Dimethyl-1,2-benzanthracene / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D011905:Genes, ras; D015603:Keratinocytes / Q000502:physiology; D007633:Keratins / Q000235:genetics* / Q000276:immunology; D008745:Methylation; D051379:Mice; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000737:chemistry; D015689:Oncogene Protein p21(ras) / Q000235:genetics*; D016761:Oncogene Proteins v-fos / Q000235:genetics; D010212:Papilloma / Q000139:chemically induced / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D012878:Skin Neoplasms / Q000139:chemically induced / Q000235:genetics*; D016038:Skin Transplantation; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D009841:Oligonucleotides; D016761:Oncogene Proteins v-fos; D012333:RNA, Messenger; D015127:9,10-Dimethyl-1,2-benzanthracene; D007633:Keratins; D015689:Oncogene Protein p21(ras); D013755:Tetradecanoylphorbol Acetate