Vascular Endothelial Growth Factor (VEGF) Expression in Canine Mammary Carcinomas
VEGF is an important angiogenic marker. High levels of VEGF protein expression were verified in invasive mammary tumors.
VEGF gene and protein expression were evaluated in canine mammary carcinomas and compared its expressions with clinical and histopathological features.
Fresh samples from mammary carcinomas (n = 30) and normal glands (n = 12) were evaluated for VEGF gene expression by RT-qPCR. From the same tumors samples were collected, formalin-fixed and paraffin-embedded to assess VEGF protein expression by immunohistochemistry. Evaluation of VEGF protein expression was performed by the distribution of cytoplasmic positively immunostained tumor cells in scores: 1 (< 25% cells positive), 2 (26% to 50% cells positive) and 3 (> 51% cells positive). Gene and protein expression were also correlated with clinical (tumor size, presence of regional lymph node metastasis and overall survival) and histopathology (histological type and grade). The patients of this study had a followup of 2 years.
No statistical difference between the groups was observed in gene expression (p = 0,1786), but protein expression evaluation showed an increase in VEGF levels in mammary carcinomas when compared to normal mammary glands (p = 0,0071). We didn't find correlation between VEGF gene and protein expression with clinical and histopathological aspects.
The difference observed between gene and protein expression suggests an involvement of another protein control mechanism like gene mutation or miRNA influence. High VEGF protein expression has an important role in tumorigenesis process of canine mammary tumors.
Grant 2013/03940-4, São Paulo Research Foundation (FAPESP)