Short hairpin RNA-mediated gene silencing of ADAM17 inhibits the growth of breast cancer MCF­7 cells in vitro and in vivo and its mechanism of action.

ABSTRACT

A disintegrin and metalloprotease 17 (ADAM17) is highly expressed in many malignant tumors and is closely related to their development. We showed in a previous study that silencing of ADAM17 by siRNA inhibited the growth of MCF­7 breast cancer cells in vitro and in vivo. In the present study, we investigated the effects of ADAM17-short hairpin RNA (ADAM17­shRNA) on MCF­7 breast cancer cells and explored the potential action pathway. In vitro, transfection of shRNAs was performed using a lentivirus, and the effects of ADAM17­shRNA on invasion, proliferation and cell cycle distribution of MCF­7 cells were assessed by Boyden chamber method, real­time cell analysis and flow cytometry, respectively. In vivo, MCF­7 cells with different administrations were transplanted subcutaneously into nude mice, and the effect of ADAM17­shRNA on the growth of transplanted tumors was assessed. In addition, the morphological structures were observed by H&E staining, and the expression of ADAM17 and Ki­67 was assessed by immunohistochemistry; expression of ADAM17, EGFR, p­EGFR, AKT, p­AKT, ERK and p­ERK proteins was assessed by western blotting, respectively. Our data showed that ADAM17­shRNA successfully inhibited ADAM17 mRNA expression, invasion and proliferation of MCF­7 cells resulting in G0/G1 phase arrest, and significantly inhibited the growth of transplanted tumors with larger areas of necrosis, low expression of ADAM17 and Ki-67 and reduced protein expression of ADAM17, EGFR, p­EGFR, AKT, p­AKT, ERK, and p­ERK in the tumor tissues. The present research suggests that ADAM17­shRNA can inhibit MCF­7 cell invasion and proliferation in vitro and inhibit MCF­7 xenograft growth in vivo through the EGFR/PI3K/AKT and EGFR/MEK/ERK signaling pathways.