The malignant conversion step of mouse skin carcinogenesis

Area of Science:

• Oncology
• Molecular Biology
• Dermatology

Background:

• Benign squamous papillomas often precede squamous cell carcinoma in mouse skin.
• Malignant conversion of papillomas can be enhanced by mutagens, suggesting a genetic requirement.
• Reduced transcription of epidermal differentiation markers is a hallmark of malignant phenotype.

Purpose of the Study:

• To investigate the genetic changes underlying malignant conversion in epidermal carcinogenesis.
• To identify specific oncogenes involved in the transition from benign papillomas to squamous cell carcinoma.
• To characterize the molecular alterations associated with malignant transformation in epidermal cells.

Main Methods:

• Induction of benign papillomas in mouse skin.
• Treatment of papilloma-bearing mice with chemical mutagens.
• Introduction of oncogenes (v-rasHa, v-fos, myc, adenovirus E1A) into cultured epidermal cells and benign tumor cells.
• Analysis of epidermal differentiation markers and protease secretion.

Main Results:

• The v-rasHa oncogene can confer a benign phenotype to cultured epidermal cells.
• Transfection with the fos oncogene transforms benign tumor cells into malignant carcinomas.
• Simultaneous introduction of v-ras and v-fos oncogenes leads to malignant transformation of normal epidermal cells.
• Fos-induced carcinomas exhibit reduced differentiation markers and secrete specific proteases.

Conclusions:

• A limited number of genes are involved in epidermal carcinogenesis.
• The fos oncogene, particularly in conjunction with v-ras, plays a critical role in malignant conversion.
• Understanding these genetic pathways can aid in early diagnosis and therapeutic strategies for skin cancer.