Tyrosine kinase-deficient EphB6 receptor-dependent alterations in proteomic profiles of invasive breast carcinoma cells as determined by difference gel electrophoresis.

The expression profiles of the erythropoietin producing hepatocellular carcinoma (Eph) receptor family of tyrosine kinases have been previously shown to provide molecular signatures of normal breast cells, breast tumor cells and invasive breast carcinoma cells. In particular, the expression of EphB6 receptor is lost in invasive breast carcinoma cell line MDA-MB-231. The comparative proteomic profiles of native and EphB6-expressing MDA-MB-231 cells using difference gel electrophoresis (DIGE) and liquid chromatography-mass spectrometry of selected proteins are presented in this study. The expression of more than 70 proteins was significantly altered in EphB6-transfected MDA-MB-231 cells. These altered proteins are involved in glycolysis, cell cycle regulation, tumor suppression, cell proliferation, mitochondrial metabolism, mRNA splicing, DNA replication and repair. Although the majority of these proteins have been implicated in tumorigenesis, the impairment of energy homeostasis and altered regulation of signaling pathways appear to be noteworthy targets of EphB6. Based on the identities of altered proteins and the pathways regulated by these proteins, this study suggests that the interactions of EphB6 with a wide variety of proteins lead to altered proteomic profile of EphB6-transfected MDA-MB-231 cells.