Vascular Endothelial Growth Factor A (VEGF-A) concentrations in canine malignant mammary tumours with and without metastases to regional lymph nodes

Abstract

In the present study the concentrations of vascular endothelial growth factor A (VEGF-A) in canine malignant mammary gland tumours and normal mammary gland tissues were examined. The homogenates of 36 malignant mammary gland tumours (26 tumours without metastases to regional lymph nodes and 10 tumours with metastases to regional lymph nodes) and 10 samples of normal canine mammary gland tissue were used in the study. The concentrations of VEGF-A in the homogenates were determined using specific canine ELISA assay. The results obtained showed that the mean concentration of VEGF-A in the malignant mammary tumours, both with and without metastases to regional lymph nodes (65.85 ± 28.24 pg/mg protein and 23.09 ± 10.86 pg/mg protein, respectively), was significantly higher (p < 0.05) than in the normal mammary glands (11.45 ± 6.47 pg/mg protein). Moreover, the mean concentration of VEGF-A was significantly higher (p < 0.05) in the malignant mammary tumors with metastases to regional lymph nodes compared to that in the non-metastatic malignant mammary tumours. In the homogenates of mammary carcinomas, the mean VEGF-A concentration was higher in grade 3 tumours (61.96 ± 38.60 pg/mg protein) compared to that in grade 1 and grade 2 tumours (20.34 ± 7.53 pg/mg protein and 29.75 ± 17.65 pg/mg protein, respectively). A significant difference (p < 0.05) in VEGF-A concentration between grade 3 and grade 1 tumours was found. These results indicate that increasing the malignancy of canine mammary tumours and their potential for metastasis is accompanied by an increased production of VEGF-A in the tumour. This may suggest that an increased production of VEGF-A plays a role in malignant transformation and facilitates spreading of tumor cells and formatting of metastases in canine malignant mammary gland tumours.