GENE-EXPRESSION SCREENING FOR SPECIFIC GENES ASSOCIATED WITH MOUSE MAMMARY-TUMOR DEVELOPMENT

The preneoplastic hyperplastic alveolar nodule is a frequent and well- characterized precursor to mammary tumors in the mouse. Although the b iological characteristics of the preneoplastic state have been underst ood for many years, the molecular alterations associated with preneopl asia and tumorigenicity are unknown. We applied the technique of diffe rential display of mRNA to two closely matched cell populations of mam mary preneoplasias that differed only in their tumorigenic potential. Two mRNAs were isolated that were overexpressed only in tumorigenic pr eneoplasias and in tumors and not in normal pregnant mammary gland or in nontumorigenic preneoplasias. Partial nucleotide sequencing indicat ed that one of the mRNAs had not yet been described, whereas the secon d mRNA was highly homologous to a relatively uncharacterized gene term ed pT-2. These results illustrate the utility of the differential disp lay method for isolating and identifying uniquely expressed genes from tissues maintained in the microenvironment where tumors arise natural ly. (C) 1993 Wiley-Liss, Inc.