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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.
Insights
Researchers identified specific genes activated during skin cancer development in mice using recombinant DNA technology. These gene markers show promise for understanding multi-stage carcinogenesis.
Area of Science:
- Molecular Biology
- Oncology
- Genetics
Background:
- Skin carcinogenesis is a complex multi-stage process.
- Identifying molecular markers associated with cancer progression is crucial for understanding disease mechanisms.
Purpose of the Study:
- To isolate and characterize gene sequences activated during multi-stage skin carcinogenesis in mice.
- To identify potential molecular markers for early detection and understanding of cancer development.
Main Methods:
- Recombinant DNA techniques and differential screening of cDNA libraries.
- Hybridization experiments using cDNA probes (pmal-1 to pmal-6) on RNA from normal epidermis and tumors.
- Southern analysis to characterize repetitive sequences.
Main Results:
- 35 cDNA clones with differential hybridization signals were identified from 5000 screened.
- Six distinct cDNA clones (pmal-1 to pmal-6) showed strong expression in carcinomas but weak/no expression in normal epidermis.
- Transcriptional activation of mal-1, -2, and -3 related sequences was observed even in the benign papilloma stage.
Conclusions:
- Specific gene sequences are transcriptionally activated during early stages of skin carcinogenesis.
- The identified cDNA clones represent potential molecular markers for multi-stage carcinogenesis.
- These findings contribute to understanding the genetic alterations during skin tumor development.