Aberrant expression of receptor tyrosine kinase EphA7 in breast cancers

Receptors tyrosine kinase of Eph family play important roles in the vascular development, tissue-border formation, cell migration, axon guidance and angiogenesis. They are reported overexpressed in certain human cancers. The over-expression of Eph receptors in cancers is associated with malignant transformation, tumor metastasis, tumor progression and prognosis. Among the Eph family genes, relatively less attention has been directed toward EphA7 in human tumors. Down-regulation of EphA7 by hypermethylation was found in colorectal cancer, germinal center B-cell lymphoma, gastric cancer, and prostate cancer. The potential role of EphA7 in carcinogenesis of human breast carcinoma has not been addressed. In the present study, we tested the expression of EphA7 protein in normal breast cell line MCF-10A, breast cancer cell lines MCF-7, MDA-MB-231, SK-BR-3 and in a set of 150 invasive ductal cancer specimens by using immunohistochemical staining with an EphA7 specific polyclonal antibody. The relationship between EphA7 protein expression and clinicopathological parameters was analyzed. Loss of EphA7 expression was found in breast cancer cell lines and invasive ductal cancer specimens. The expression of EphA7 was associated with grade (P = 0.014), TNM stage (P = 0.029), lymph node metastasis (P = 0.018) and HER2 status (P = 0.005). Our data indicate that the EphA7 protein lost in most breast cancer samples. The function of EphA7 protein in carcinogenesis of breast cancer may be diverse.