ADAM17 promotes breast cancer cell malignant phenotype through EGFR-PI3K-AKT activation

Abstract

A disintegrin and metalloproteinase-17 (ADAM17) is involved in proteolytic ectodomain shedding of several membrane-bound growth factors and cytokines. The expression and activity of ADAM17 increase under some pathological conditions such as stroke and glioma. ADAM17 promotes neural progenitor cell migration and contributes to stroke-induced neurogenesis after stroke and brain tumor growth and invasion. In the present study, we sought to elucidate whether ADAM17 contributes to breast cancer progression and its mechanisms. To this end, we examined the role of ADAM17 in the proliferation, invasion, and tube formation of MDA-MB-231 breast cancer cells in vitro. Stable transfection of the MDA-MB-231 cell line with either a plasmid for over-expression of human ADAM17, or a siRNA to ADAM17 was employed in this study to establish high or low ADAM17 expression in breast cancer cells, respectively. For study of mechanism, the ADAM17 inhibitor TAPI-2 and the PI3K-AKT inhibitor LY294002 were used to counteract high ADAM17 expression or the activated PI3K-AKT pathway. Proliferation of MDA-MB-231 breast cancer cells were tested by MTT, Bromodeoxyuridine incorporation assay, growth curve, and sulforhodamine B assay. Matrigel invasion assays were used to assess the ability of MDA-MB-231 cells to penetrate the Extra Cellular Matrix. A Matrigel tube formation assay was performed to test capillary tube formation ability. EGFR-PI3K-Akt pathway activation in MDA-MB-231 cells under different ADAM17 expression levels were tested by Western blot and ELISA. Our data show that ADAM17 promotes the MDA-MB-231 malignant phenotype by increased proliferation, invasion and angiogenesis. TGF-α, VEGF secretion and VEGF expression was increasing by ADAM17 and counteracted by ADAM17 siRNA, TAPI-2, and LY294002 in MDA-MB-231 cells. ADAM17 activated, whereas ADAM17 siRNA, TAPI-2, and LY294002 deactivated the EGFR-PI3K-AKT signal pathway, which correlated with MDA-MB-231 cell malignant phenotype changes. This study suggests ADAM17 contributes to breast cancer progression through activation of the EGFR-PI3K-AKT signal pathway.