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Proto-oncogene expression during two-stage carcinogenesis in mouse skin
Abstract:
The level of expression of the cellular homologues to the oncogenes rasHa, rasKi, fos, myc, abl and raf was determined in chemically induced tumors, in mouse skin and in mouse epidermis after treatment with a tumor promoter. No significant increase in expression was found for any of the above proto-oncogenes. The expression of abl was reduced in both papillomas and carcinomas and after repeated applications of 12-O-tetradecanoylphorbol-13-acetate (TPA). Treatment of primary mouse epidermal cells with TPA in vitro failed to induce any marked alterations in proto-oncogene expression. Cell lines derived by treatment of epidermal cells with chemical carcinogens showed expression levels similar to untreated primary epidermal basal cells. These results suggest that increased expression of the proto-oncogenes under study is not required for tumor induction in mouse skin. The lower level of expression of abl in tumors and after repeated applications of TPA may indicate a role for this gene in some aspect of epidermal proliferation or differentiation.
Insights
Increased expression of key cellular oncogenes is not required for mouse skin tumor development. However, abl gene expression was notably reduced in tumors and after promoter treatment.
Area of Science:
- Oncology
- Molecular Biology
- Dermatology
Background:
- Proto-oncogenes play critical roles in cellular growth and differentiation.
- Alterations in proto-oncogene expression are frequently observed in various cancers.
- Understanding proto-oncogene involvement in skin carcinogenesis is crucial for developing targeted therapies.
Purpose of the Study:
- To investigate the expression levels of specific proto-oncogenes (rasHa, rasKi, fos, myc, abl, raf) during chemical carcinogenesis in mouse skin.
- To determine if elevated proto-oncogene expression is a prerequisite for tumor initiation and promotion.
- To explore the potential role of the abl gene in epidermal proliferation and differentiation.
Main Methods:
- Quantitative analysis of proto-oncogene expression in chemically induced mouse skin tumors, epidermis, and papillomas.
- Treatment of primary mouse epidermal cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) in vitro.
- Analysis of proto-oncogene expression in cell lines derived from chemically treated epidermal cells.
Main Results:
- No significant increase in the expression of rasHa, rasKi, fos, myc, or raf was observed in tumors or after TPA treatment.
- A consistent reduction in abl gene expression was detected in both papillomas and carcinomas.
- Repeated TPA application and in vitro treatment of epidermal cells with TPA did not induce significant alterations in the expression of the studied proto-oncogenes.
Conclusions:
- Increased expression of the investigated proto-oncogenes is not essential for mouse skin tumor induction.
- The reduced expression of abl in tumors and upon TPA treatment suggests a potential role in epidermal proliferation or differentiation processes.