| Epithelial-mesenchymal transition (EMT) represents a retro-differentiation phenomenon allowing adult cells to acquire stem-like cell phenotypes. Cancer cells undergoing EMT show increased migratory capacity that demands higher energy production. Both endpoint outcomes implicate mitochondrial (Mt) participation in EMT. This is because that, in addition to be major ATP producers, Mt have been found to regulate the differentiation of both adult cells and stem cells. However, the role of Mt in EMT is not fully understood.Aim:To investigate the mechanistic role of Mt in the EMT of A549 cells.Methods:In this study, functional Mt were isolated from A549 lung cancer cells using our well-characterized model of EMT induction with TGF-β1 and then analyzed by SILAC-based proteomics. Mt proteins from control and TGF-β1-treated groups were mixed, digested, identified and quantified by mass spectrometry and MaxQuant. Biological functions of the differentially expressed proteins (DEPs) were characterized bioinformatically by Ingenuity Pathways Analysis (IPA) and GOstats software, followed by biological confirmation.Results:In total,141 Mt proteins were found to be up-regulated while 41 Mt proteins down-regulated in A549 cells after TGF-β1 treatment. IPA and GOstats results indicated that the DEPs were primarily associated with the cell movement networks in addition to cell death, oxidative phosphorylation, ATP synthesis and other functions. The inner membrane potential of Mt (ΔΨm) increased in A549 cells undergoing EMT, and the amount of elongated Mt also increased according to TEM observation.Conclusions:Incorporation and composition of Mt proteins of A549 cells in EMT showed notable variations. The potential mechanisms include the co-localization of migration-associated proteins in Mt via Mt proliferation and turnover, and the augmented energy production of Mt by increasing oxidative phosphorylation.
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