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: Romina M Wiedmann, Karin von Schwarzenberg, Andrea Palamidessi, Laura Schreiner, Rebekka Kubisch, Johanna Liebl, Christina Schempp, Dirk Trauner, Gyorgy Vereb, Stefan Zahler, Ernst Wagner, Rolf Müller, Giorgio Scita, Angelika M Vollmar
• Journal: Cancer research (Cancer Res) Vol. 72 Issue 22 Pg. 5976-87 (Nov 15 2012) ISSN: 1538-7445 [Electronic] United States
• PMID: 22986742 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: ©2012 AACR.

Chemical References

• Macrolides
• RAC1 protein, human
• Thiazoles
• archazolid A
• ErbB Receptors
• Vacuolar Proton-Translocating ATPases
• rab5 GTP-Binding Proteins
• rac1 GTP-Binding Protein

Topics

• Animals
• Breast Neoplasms (drug therapy, enzymology, pathology)
• Cell Line, Tumor
• Cell Movement (drug effects)
• Cell Polarity (drug effects)
• Down-Regulation
• ErbB Receptors (metabolism)
• Female
• Humans
• Macrolides (pharmacology)
• Mice
• Mice, Inbred BALB C
• Neoplasm Metastasis
• Thiazoles (pharmacology)
• Vacuolar Proton-Translocating ATPases (antagonists & inhibitors)
• Xenograft Model Antitumor Assays
• rab5 GTP-Binding Proteins (metabolism)
• rac1 GTP-Binding Protein (antagonists & inhibitors, metabolism)