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Cooperation of p53 loss of function and v‐Ha‐ ras in transformation of mouse keratinocyte cell lines
Author(s) -
Azzoli Christopher G.,
Sagar Manish,
Wu Anita,
Lowry David,
Hennings, Henry,
Morgan David L.,
Weinberg Wendy C.
Publication year - 1998
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/(sici)1098-2744(199801)21:1<50::aid-mc7>3.0.co;2-t
Subject(s) - biology , keratinocyte , cell culture , oncogene , mutant , microbiology and biotechnology , transfection , in vitro , cancer research , cell , gene , genetics , cell cycle
We previously demonstrated that after transduction with the v‐Ha‐ ras oncogene and grafting onto nude mouse hosts, primary epidermal keratinocytes with a null mutation in the p53 gene form tumors with increased growth rates and predisposition to malignant conversion relative to p53 wild‐type keratinocytes (Weinberg WC, et al., Cancer Res 54:5584–5592, 1994). To further explore the cooperation between p53 loss of function and activation of the ras oncogene, cell lines were established from the normal epidermises of newborn and adult p53 ‐null mice, and parallel subclones were reconstituted with the p53 val135 temperature‐sensitive mutant. Reconstituted lines C, G, N, and V demonstrated functional p53 transcriptional activator activity at the wild‐type–permissive temperature of 32°C, compared with the hygromycin‐selected control line X and parental p53 ‐null lines NHK4 and AK1b. Hygromycin‐selected subclones, but not the parental lines, made normal skin in vivo; all cell lines made carcinomas after introduction of v‐Ha‐ ras , independent of p53 status. These cell lines were compared in vitro at 32°C to maximize the amount of p53 val135 in the wild‐type conformation. Expression of v‐Ha‐ras did not consistently alter p53‐mediated transcriptional activity, suggesting that ras acts downstream or independently of p53. No correlation was observed between p53‐mediated transcriptional activity and in vitro growth rates, colony formation after exposure to ultraviolet light, or suppression by normal neighboring keratinocytes. However, keratinocyte cell lines devoid of p53 and expressing v‐Ha‐ ras formed colonies in soft agar; this was blocked at 32°C in all cell lines reconstituted with p53 val135 . These keratinocyte lines provide a model for exploring the role of p53 and the interaction of p53 and ras in keratinocyte transformation. Mol. Carcinog. 21:50–61, 1998. © 1998 Wiley‐Liss, Inc.