Analysis of Hypoxia-Inducible Factor-1α Expression Relative to Other Key Factors in Malignant Canine Mammary Tumours

Hypoxia-inducible factor (HIF)-1α plays important physiological roles, but is also of significance in carcinogenesis in man and animals. This study aimed to identify HIF-1α expression in malignant canine mammary tumours (CMTs) and to find correlations with other key factors by using immunohistochemistry (IHC). The histological classification, grading and evaluation of lymphatic invasion were achieved by examining sections stained by haematoxylin and eosin. Determination of molecular subtype, expression of HIF-1α, oestrogen receptor (OR), progesterone receptor (PR), human epidermal growth factor receptor (HER)-2, Ki67, vascular endothelial growth factor (VEGF) and E-cadherin was evaluated by IHC in 87 samples of malignant CMTs. HIF-1α expression correlated significantly with histological type, grade of cancer, negativity for OR and expression of Ki67 and VEGF. Lymphatic invasion, molecular subtype, PR, HER-2 and E-cadherin levels did not significantly correlate with HIF-1α expression. The results of this study imply that HIF-1α may potentially play a role in increased malignancy of CMTs, as it does in human breast cancer.