title: β-Arrestin2 regulates lysophosphatidic acid-induced human breast tumor cell migration and invasion via Rap1 and IQGAP1.
abstract: β-Arrestins play critical roles in chemotaxis and cytoskeletal reorganization downstream of several receptor types, including G protein-coupled receptors (GPCRs), which are targets for greater than 50% of all pharmaceuticals. Among them, receptors for lysophosphatidic acid (LPA), namely LPA(1) are overexpressed in breast cancer and promote metastatic spread. We have recently reported that β-arrestin2 regulates LPA(1)-mediated breast cancer cell migration and invasion, although the underlying molecular mechanisms are not clearly understood. We show here that LPA induces activity of the small G protein, Rap1 in breast cancer cells in a β-arrestin2-dependent manner, but fails to activate Rap1 in non-malignant mammary epithelial cells. We found that Rap1A mRNA levels are higher in human breast tumors compared to healthy patient samples and Rap1A is robustly expressed in human ductal carcinoma in situ and invasive tumors, in contrast to the normal mammary ducts. Rap1A protein expression is also higher in aggressive breast cancer cells (MDA-MB-231 and Hs578t) relative to the weakly invasive MCF-7 cells or non-malignant MCF10A mammary cells. Depletion of Rap1A expression significantly impaired LPA-stimulated migration of breast cancer cells and invasiveness in three-dimensional Matrigel cultures. Furthermore, we found that β-arrestin2 associates with the actin binding protein IQGAP1 in breast cancer cells, and is necessary for the recruitment of IQGAP1 to the leading edge of migratory cells. Depletion of IQGAP1 blocked LPA-stimulated breast cancer cell invasion. Finally, we have identified that LPA enhances the binding of endogenous Rap1A to β-arrestin2, and also stimulates Rap1A and IQGAP1 to associate with LPA(1). Thus our data establish novel roles for Rap1A and IQGAP1 as critical regulators of LPA-induced breast cancer cell migration and invasion.
authors: Department of Physiology and Pharmacology, Western University, London, Ontario, Canada.
authors: Mistre
authors: M
authors: Alemayehu
authors: Magdalena
authors: M
authors: Dragan
authors: Cynthia
authors: C
authors: Pape
authors: Iram
authors: I
authors: Siddiqui
authors: David B
authors: DB
authors: Sacks
authors: Gianni M
authors: GM
authors: Di Guglielmo
authors: Andy V
authors: AV
authors: Babwah
authors: Moshmi
authors: M
authors: Bhattacharya
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D001940:Breast / Q000378:metabolism; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D002448:Cell Adhesion / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002633:Chemotaxis / Q000187:drug effects; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008246:Lysophospholipids / Q000494:pharmacology*; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D049368:Receptors, Lysophosphatidic Acid / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000089804:Shelterin Complex; D015398:Signal Transduction / Q000187:drug effects; D034501:Telomere-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D000071557:beta-Arrestins; D020703:ras GTPase-Activating Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D019390:Arrestins; C101203:IQ motif containing GTPase activating protein 1; D008246:Lysophospholipids; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D049368:Receptors, Lysophosphatidic Acid; D000089804:Shelterin Complex; C440809:TERF2IP protein, human; D034501:Telomere-Binding Proteins; D000071557:beta-Arrestins; D020703:ras GTPase-Activating Proteins; C032881:lysophosphatidic acid