DIFFERENTIAL EXPRESSION OF THE H-RAS MUTATED AND NORMAL ALLELES IN RABBIT DMBA-INDUCED KERATOACANTHOMAS

Keratoacanthomas (KAs) are benign and self-regressing tumors in which a high incidence of the mutated H-ras oncogene has been observed both in humans and in experimental models. To determine the level of expres sion of the mutated H-ras allele with respect to its normal counterpar t in 7,12-dimethylbenze-(a)anthracene (DMBA)-induced KAs in rabbit ski n, we have utilized a quantitative technique based on reverse transcri ption polymerase chain reaction (RT-PCR) and selective cleavage of the mutated molecules of the H-ras gene. Analysis of 16 KAs showed that t he mutated H-ras transcripts were up to 3-fold more abundant than the non-mutated H-ras transcript in the different tumors. This higher expr ession of the mutated allele appears to correlate with increased diffe rentiation in the KAs and in turn may contribute to tumor regression. (C) 1995 Wiley-Liss, Inc.