A ROS/Akt/NF-kB Signaling Cascade Mediates Epidermal Growth Factor-Induced Epithelial-Mesenchymal Transition and Invasion in Human Breast Cancer Cells

Abstract

Aim: As one of the most widely used anti-diabetic drug for type II diabetes, metformin has been shown to exhibit anti-cancer activity in recent years. Epidermal growth factor (EGF) and its receptor, EGFR, play important roles in cancer metastasis in various tumors, including breast cancer. Epithelial-mesenchymal transition (EMT) is a critical process forcancerinvasion and metastasis. In this study, we use EGF as a metastatic inducer to investigate the effect of metformin on cancer cell migration, invasion and EMT.

Methods: Human breastcancer MCF-7cells wereexposed to EGFwith or withoutmetforminor NAC. The effects of metformin on breastcancer cell proliferation were analyzed usingMTT assay. The production of ROS was tested using DCFH-DA. The migratory and invasive abilitiesof tumor cells were analyzed using wound healing assayand Transwell invasion assay, respectively. The expressions of E-cadherin, N-cadherin and Snailwere tested using qRT-PCR and western blotting at mRNA and proteinlevels. The activationof Akt and NF-kB were measured by western blotting.

Results: Our resultsshowed that metformin inhibited breast cancer cell proliferation in a dose-dependent mannerwith or without EGF.EGF-induced alterations in cell morphology that are characteristic of EMT were reversed by metformin. Metformin also inhibited the EGF-modulated expression of E-cadherin, N-cadherin and Snail and further suppressed cell invasion and migration. In addition, metformin suppressed EGF-induced phosphorylation of Aktand NF-kB.ROS is involved in EGF-induced cancer invasion and activation of PI3K/Akt/NF-kBpathway.

Conclusion: Taken together, these data indicate that metformin suppresses EGF-induced breast cancer cell migration, invasion and EMT through the inhibition of the PI3K/Akt/NF-kBpathway. These results provide a novel mechanism to explain the role of metformin as a potent anti-metastatic agent in breast cancer cells.