Role of Angiogenesis and Expression of Vascular Endothelial Growth Factor in Mouse Skin Carcinogenesis

ABSTRACT

BACKGROUND: Angiogenesis is crucial for many biological processes such as embryogenesis, cyclic changes in the endometrium and wound healing. It is also critical for the growth, invasion and metastasis of solid tumors. Vascular endothelial growth factor (VEGF) acts as a mitogen for endothelial cells and is expressed by the presence of various tumor cells. The objective of this study is to evaluate if angiogenesis is involved in the mouse skin carcinogenesis and if VEGF is related to angiogenesis. METHODS: We induced premalignant and malignant lesions on mouse (BALB/c) skin using the two stage chemical carcinogenesis moedl, DMBA (7,12-dimethylbenzanthracene) initiation and TPA (tetra decanoyl-phorbol-acetate) promotion. And we analysed the microvessel densities (MVD) and expression of VEGF in various stages of premalignant and malignant lesions by immunohistochemical studies. RESULTS: Squamous papillomas, keratoacanthoma, dermatofibroma, and squamous cell carcinomas were developed in 20 weeks. There were no differences in the incidence of benign and malignant tumors between 10-week and 20-week promotion groups. There were significant increases in MVD from normal and hyperplastic skin through premalignant lesion to invasive squamous cell carcinoma (p<0.0005). But the degree of VEGF expression neither correlated with neither MVD nor the tumor groups. CONCLUSIONS: Increased angiogenesis begins from the hyperplastic stage. VEGF produced by tumor cells may not play major roles in the angiogenesis in the two stage chemical carcinogenesis model of the mouse skin.