title: Molecular cloning of sequences activated during multi-stage carcinogenesis in mouse skin.
abstract: Recombinant DNA techniques were employed to isolate sequences that were activated during multi-stage carcinogenesis in the skin of NMRI mice. Differential screening of 5000 cDNA clones made from poly(A)+ RNA of squamous cell carcinomas induced by 7,12-dimethylbenz[a]anthracene (DMBA) and the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA) resulted in the identification of 35 cDNA clones displaying a different hybridization signal. Eight cDNA clones, three of which proved to be identical, were used as probes in transfer hybridization experiments. These cDNA clones, designated pmal-1 to pmal-6, showed a strong signal with carcinoma RNA but either a weak or no signal with RNA from normal epidermis. Clone pmal-2 contained repetitive sequences as shown by Southern analysis resulting in a smeared RNA hybridization signal in RNA blots whereas the other five clones corresponded to discrete size classes of mRNA. Studies on the expression pattern of mal-1,-2 and -3 related sequences revealed transcriptional activation already in the benign papilloma stage of multi-step carcinogenesis.
mesh_terms: D000818:Animals; D001483:Base Sequence; D002277:Carcinoma / Q000235:genetics; D002471:Cell Transformation, Neoplastic; D003001:Cloning, Molecular; D004247:DNA / Q000032:analysis; D005260:Female; D051379:Mice; D008815:Mice, Inbred Strains; D009693:Nucleic Acid Hybridization; D010212:Papilloma / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D012334:RNA, Neoplasm / Q000032:analysis*; D012091:Repetitive Sequences, Nucleic Acid; D013539:Simian virus 40; D012878:Skin Neoplasms / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D012333:RNA, Messenger; D012334:RNA, Neoplasm; D004247:DNA