Decreased retinyl ester concentrations in UV-induced murine squamous cell carcinomas

Area of Science:

• Dermatology
• Oncology
• Biochemistry

Background:

• Ultraviolet (UV) radiation, particularly UVB and UVA, is a known carcinogen causing skin cancers.
• Vitamin A and its metabolites are crucial for cell differentiation and immune function, potentially influencing cancer development.

Purpose of the Study:

• To investigate the role of vitamin A in UV-induced skin carcinogenesis in hairless mice.
• To analyze vitamin A concentrations and esterifying activity in skin tumors and normal tissues.

Main Methods:

• Hairless mice were exposed to UVB and UVA radiation to induce squamous cell carcinomas.
• Mice received diets with or without vitamin A supplementation.
• Vitamin A levels (retinol, retinyl esters) and acyl-CoA:retinol acyltransferase activity were measured in serum, liver, epidermis, and tumors.

Main Results:

• Vitamin A supplementation increased liver and epidermal vitamin A levels but did not prevent tumor formation.
• Tumors exhibited significantly lower vitamin A concentrations compared to perilesional epidermis, especially in supplemented mice.
• The reduction in tumor vitamin A was primarily due to decreased retinyl esters, while retinol levels were elevated.

Conclusions:

• Vitamin A supplementation alone is insufficient to prevent UV-induced skin cancer in this model.
• Altered vitamin A metabolism, specifically reduced retinyl ester levels in tumors, may play a role in murine photo-carcinogenesis.
• The underlying mechanism for reduced retinyl ester concentration in tumors remains unclear but warrants further investigation.