Premium
Malignant conversion of murine squamous papilloma cell lines by transfection with the fos oncogene
Author(s) -
Greenhalgh David A.,
Yuspa Stuart H.
Publication year - 1988
Publication title -
molecular carcinogenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 97
eISSN - 1098-2744
pISSN - 0899-1987
DOI - 10.1002/mc.2940010209
Subject(s) - biology , transfection , microbiology and biotechnology , oncogene , cell culture , cancer research , cell , papilloma , malignant transformation , keratin , cell cycle , pathology , paleontology , medicine , genetics
Murine papilloma cell lines 308 and SP‐1 have been used as recipients for transfected oncogenes to investigate malignant conversion. These cell lines express an activated c ras Ha gene with a codon 61 mutation and produce squamous papillomas when transplanted as skin grafts onto nude mice. They are not tumorigenic by subcutaneous injection. Both papilloma cell lines were stably transfected with plasmid DNA containing either a rearranged murine plasmacytoma‐derived c‐ myc (minus exon 1), adenovirus 5 E1A , FBJ v‐ fos or a human c‐ fosl FBJ v‐ fos chimera, using cotransfection with the neomycin resistance gene contained in pSV 2 neo to select for transformants. Southern and northern blotting analysis confirmed the uptake and expression of exogenous DNA in both G418‐selected cell lines and in the derived tumors. Unlike the E1A ‐ and myc ‐containing plasmids, both fos constructs caused malignant conversion in either cell line, as defined by the squamous cell carcinoma histology of tumors from grafted cells and the development of carcinomas after subcutaneous injection into athymic nude mice. Immunofluorescence analysis for specific keratin gene expression indicated that tumors derived by introduction of either of the fos oncogenes were devoid of staining for K1, a 67 kDa epidermal keratin that is expressed in papillomas but not in squamous carcinomas. Tumors from E1A , myc , or pSV 2 neo transfectants expressed K1, although in a focal distribution. The malignant phenotype induced by the fos oncogene constructs was not associated with the ability to form agar colonies in vitro or to express γ‐glutamyl transpeptidase in the tumors. Since both 308 and SP‐1 were sensitive to the fos oncogene for malignant conversion and insensitive to E1A or myc , it is possible that fos may cooperate with the endogenous‐activated c‐ ras Ha gene to convert these cells to malignancy. However, since γ‐glutamyl transpeptidase activity is found in the majority of chemically induced mouse skin carcinomas that possess an activated c ras Ha gene, fos activation may not be a common pathway for spontaneous malignant conversion.