Negative regulation of urokinase receptor activity by a GPI-specific phospholipase C in breast cancer cells

The urokinase receptor (uPAR) is a glycosylphosphatidylinositol (GPI)-anchored protein that promotes tissue remodeling, tumor cell adhesion, migration and invasion. uPAR mediates degradation of the extracellular matrix through protease recruitment and enhances cell adhesion, migration and signaling...

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Published in:	eLife Vol. 6
Main Authors:	van Veen, Michiel, Matas-Rico, Elisa, van de Wetering, Koen, Leyton-Puig, Daniela, Kedziora, Katarzyna M, De Lorenzi, Valentina, Stijf-Bultsma, Yvette, van den Broek, Bram, Jalink, Kees, Sidenius, Nicolai, Perrakis, Anastassis, Moolenaar, Wouter H
Format:	Journal Article
Language:	English
Published:	England eLife Science Publications, Ltd 29.08.2017 eLife Sciences Publications Ltd eLife Sciences Publications, Ltd
Subjects:	Analysis Animals Breast cancer Breast Neoplasms - genetics Breast Neoplasms - metabolism Breast Neoplasms - pathology Cancer Biology Cancer cells Cancer research Cell Adhesion Cell Biology Cell Line, Tumor Cell Proliferation Cell surface Cell Transformation, Neoplastic - genetics Cell Transformation, Neoplastic - metabolism Cell Transformation, Neoplastic - pathology Clustered Regularly Interspaced Short Palindromic Repeats Down-regulation Enzymes Extracellular matrix Female Flow cytometry GDE3 Gene Expression Regulation, Neoplastic Gene Knockout Techniques - methods Glycerophosphodiester phosphodiesterase Glycosylphosphatidylinositol HEK293 Cells Humans Hydrolysis Integrins Isoenzymes - genetics Isoenzymes - metabolism Ligands Localization Medical research Mice Mice, Nude Microscopy Models, Molecular Motility Neoplasm Transplantation Phospholipase C Phospholipases Phosphoric Diester Hydrolases - genetics Phosphoric Diester Hydrolases - metabolism Physiology Proteases Proteins Receptors, Urokinase Plasminogen Activator - antagonists & inhibitors Receptors, Urokinase Plasminogen Activator - genetics Receptors, Urokinase Plasminogen Activator - metabolism RNA, Small Interfering - genetics RNA, Small Interfering - metabolism Rodents Scientific equipment industry Signal Transduction Statistical analysis Thrombolytic drugs Tumor Burden Tumors U-Plasminogen activator Vitronectin Vitronectin - genetics Vitronectin - metabolism Xenografts United States cell biology signal transduction GDE3 cancer biology glycosylphosphatidylinositol human glycerophosphodiester phosphodiesterase
ISSN:	2050-084X, 2050-084X
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Summary:	The urokinase receptor (uPAR) is a glycosylphosphatidylinositol (GPI)-anchored protein that promotes tissue remodeling, tumor cell adhesion, migration and invasion. uPAR mediates degradation of the extracellular matrix through protease recruitment and enhances cell adhesion, migration and signaling through vitronectin binding and interactions with integrins. Full-length uPAR is released from the cell surface, but the mechanism and significance of uPAR shedding remain obscure. Here we identify transmembrane glycerophosphodiesterase GDE3 as a GPI-specific phospholipase C that cleaves and releases uPAR with consequent loss of function, whereas its homologue GDE2 fails to attack uPAR. GDE3 overexpression depletes uPAR from distinct basolateral membrane domains in breast cancer cells, resulting in a less transformed phenotype, it slows tumor growth in a xenograft model and correlates with prolonged survival in patients. Our results establish GDE3 as a negative regulator of the uPAR signaling network and, furthermore, highlight GPI-anchor hydrolysis as a cell-intrinsic mechanism to alter cell behavior. Every process in the body, from how cells divide to how they move around, is tightly regulated. For example, cells only migrate when they receive the correct signals from their environment. These signals are recognised by receptor proteins that sit on the cell surface and connect the outside signal with the cell’s response. However, in cancer cells, these processes are out of control, which is why cancer cells can grow very quickly or spread to many different parts of the body. One important receptor protein is the urokinase receptor, which helps to reorganize the tissue, for example, when wounds heal, but also enables cancer cells to grow and spread. A special feature of urokinase receptor is the way it is connected to the cell surface, namely through a molecule that acts as an anchor, called the GPI anchor. The urokinase receptor and some other GPI-anchored proteins can be released from their anchor. However, until now it was not clear why and how the urokinase receptor is released from cells, or how losing the receptor affects the cell. Now, van Veen, Matas-Rico et al. studied breast cancer cells, and discovered that an enzyme called GDE3 cuts the urokinase receptor off its GPI anchor to release the receptor from the cells. However, when breast cancer cells shed the urokinase receptor, they also lost the receptor from the cell surface in specific areas. As a result, the receptor could not work anymore. When breast cancer cells were experimentally modified to produce high levels of GDE3, the cancer cells became less mobile and aggressive. Van Veen, Matas-Rico et al. then implanted ‘normal’ breast cancer cells, and breast cancer cells with extra GDE3 into mice, and observed that the tumors of mice with additional GDE3 grew less quickly. Moreover, breast cancer patients with high levels of GDE3 tend to live longer than patients with low levels of GDE3. These results suggest that the enzyme GDE3 can suppress tumor growth. These findings uncover a new way how cells can alter their behavior, namely by cleaving GPI anchors at the cell surface. Future experiments will need to address how GDE3 itself is controlled, and if it releases other GPI-anchored proteins from cells. Once we know how to increase GDE3 activity in tumor cells, the new knowledge could one day lead to therapies to help patients with cancer.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 content type line 23 These authors contributed equally to this work. Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, United States. University of North Carolina, Chapel Hill, United States.
ISSN:	2050-084X 2050-084X
DOI:	10.7554/eLife.23649