title: The V-ATPase-inhibitor archazolid abrogates tumor metastasis via inhibition of endocytic activation of the Rho-GTPase Rac1.
abstract: The abundance of the multimeric vacuolar ATP-dependent proton pump, V-ATPase, on the plasma membrane of tumor cells correlates with the invasiveness of the tumor cell, suggesting the involvement of V-ATPase in tumor metastasis. V-ATPase is hypothesized to create a proton efflux leading to an acidic pericellular microenvironment that promotes the activity of proinvasive proteases. An alternative, not yet explored possibility is that V-ATPase regulates the signaling machinery responsible for tumor cell migration. Here, we show that pharmacologic or genetic reduction of V-ATPase activity significantly reduces migration of invasive tumor cells in vitro. Importantly, the V-ATPase inhibitor archazolid abrogates tumor dissemination in a syngeneic mouse 4T1 breast tumor metastasis model. Pretreatment of cancer cells with archazolid impairs directional motility by preventing spatially restricted, leading edge localization of epidermal growth factor receptor (EGFR) as well as of phosphorylated Akt. Archazolid treatment or silencing of V-ATPase inhibited Rac1 activation, as well as Rac1-dependent dorsal and peripheral ruffles by inhibiting Rab5-mediated endocytotic/exocytotic trafficking of Rac1. The results indicate that archazolid effectively decreases metastatic dissemination of breast tumors by impairing the trafficking and spatially restricted activation of EGFR and Rho-GTPase Rac1, which are pivotal for directed movement of cells. Thus, our data reveals a novel mechanism underlying the role of V-ATPase in tumor dissemination.
authors.affiliation: Department of Pharmacy, Pharmaceutical Biology, University of Munich, Munich, Germany.
authors.forename: Romina M
authors.initials: RM
authors.lastname: Wiedmann
authors.forename: Karin
authors.initials: K
authors.lastname: von Schwarzenberg
authors.forename: Andrea
authors.initials: A
authors.lastname: Palamidessi
authors.forename: Laura
authors.initials: L
authors.lastname: Schreiner
authors.forename: Rebekka
authors.initials: R
authors.lastname: Kubisch
authors.forename: Johanna
authors.initials: J
authors.lastname: Liebl
authors.forename: Christina
authors.initials: C
authors.lastname: Schempp
authors.forename: Dirk
authors.initials: D
authors.lastname: Trauner
authors.forename: Gyorgy
authors.initials: G
authors.lastname: Vereb
authors.forename: Stefan
authors.initials: S
authors.lastname: Zahler
authors.forename: Ernst
authors.initials: E
authors.lastname: Wagner
authors.forename: Rolf
authors.initials: R
authors.lastname: Müller
authors.forename: Giorgio
authors.initials: G
authors.lastname: Scita
authors.forename: Angelika M
authors.initials: AM
authors.lastname: Vollmar
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D016764:Cell Polarity / Q000187:drug effects; D015536:Down-Regulation; D066246:ErbB Receptors / Q000378:metabolism; D005260:Female; D006801:Humans; D018942:Macrolides / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009362:Neoplasm Metastasis; D013844:Thiazoles / Q000494:pharmacology*; D025262:Vacuolar Proton-Translocating ATPases / Q000037:antagonists & inhibitors*; D023041:Xenograft Model Antitumor Assays; D020696:rab5 GTP-Binding Proteins / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D018942:Macrolides; C107953:RAC1 protein, human; D013844:Thiazoles; C519727:archazolid A; D066246:ErbB Receptors; D025262:Vacuolar Proton-Translocating ATPases; D020696:rab5 GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein