title: The plasma membrane sialidase NEU3 regulates the malignancy of renal carcinoma cells by controlling β1 integrin internalization and recycling.
abstract: The human plasma membrane sialidase NEU3 is a key enzyme in the catabolism of membrane gangliosides, is crucial in the regulation of cell surface processes, and has been demonstrated to be significantly up-regulated in renal cell carcinomas (RCCs). In this report, we show that NEU3 regulates β1 integrin trafficking in RCC cells by controlling β1 integrin recycling to the plasma membrane and controlling activation of the epidermal growth factor receptor (EGFR) and focal adhesion kinase (FAK)/protein kinase B (AKT) signaling. NEU3 silencing in RCC cells increased the membrane ganglioside content, in particular the GD1a content, and changed the expression of key regulators of the integrin recycling pathway. In addition, NEU3 silencing up-regulated the Ras-related protein RAB25, which directs internalized integrins to lysosomes, and down-regulated the chloride intracellular channel protein 3 (CLIC3), which induces the recycling of internalized integrins to the plasma membrane. In this manner, NEU3 silencing enhanced the caveolar endocytosis of β1 integrin, blocked its recycling and reduced its levels at the plasma membrane, and, consequently, inhibited EGFR and FAK/AKT. These events had the following effects on the behavior of RCC cells: they (a) decreased drug resistance mediated by the block of autophagy and the induction of apoptosis; (b) decreased metastatic potential mediated by down-regulation of the metalloproteinases MMP1 and MMP7; and (c) decreased adhesion to collagen and fibronectin. Therefore, our data identify NEU3 as a key regulator of the β1 integrin-recycling pathway and FAK/AKT signaling and demonstrate its crucial role in RCC malignancy.
authors.affiliation: Department of Medical Biotechnology, University of Milan, Segrate, 20090 Milan, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Tringali
authors.forename: Barbara
authors.initials: B
authors.lastname: Lupo
authors.forename: Ilaria
authors.initials: I
authors.lastname: Silvestri
authors.forename: Nadia
authors.initials: N
authors.lastname: Papini
authors.forename: Luigi
authors.initials: L
authors.lastname: Anastasia
authors.forename: Guido
authors.initials: G
authors.lastname: Tettamanti
authors.forename: Bruno
authors.initials: B
authors.lastname: Venerando
mesh_terms: D002292:Carcinoma, Renal Cell / Q000201:enzymology / Q000235:genetics / Q000473:pathology*; D002448:Cell Adhesion; D002454:Cell Differentiation / Q000235:genetics; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000201:enzymology*; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm; D004705:Endocytosis / Q000235:genetics; D066246:ErbB Receptors / Q000378:metabolism; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006028:Glycosphingolipids / Q000378:metabolism; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism*; D007680:Kidney Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology*; D020781:Matrix Metalloproteinase 1 / Q000235:genetics / Q000378:metabolism; D020783:Matrix Metalloproteinase 7 / Q000235:genetics / Q000378:metabolism; D009361:Neoplasm Invasiveness; D009439:Neuraminidase / Q000378:metabolism*; D021381:Protein Transport; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D006028:Glycosphingolipids; D019012:Integrin beta1; D066246:ErbB Receptors; D051417:Focal Adhesion Kinase 1; D051057:Proto-Oncogene Proteins c-akt; C465436:Neu3 protein, human; D009439:Neuraminidase; C060932:MMP7 protein, human; D020783:Matrix Metalloproteinase 7; C522360:MMP1 protein, human; D020781:Matrix Metalloproteinase 1