NOTCH pathway inactivation promotes bladder cancer progression

Antonio Maraver1, Pablo J. Fernandez-Marcos1, Timothy P. Cash1,Marinela Mendez-Pertuz2, Marta Dueñas3, Paolo Maietta4, Paola Martinelli2,Maribel Muñoz-Martin1, Mónica Martínez-Fernández3, Marta Cañamero5,Giovanna Roncador6, Jorge L. Martinez-Torrecuadrada7, Dimitrios Grivas8,Jose Luis de la Pompa8, Alfonso Valencia4, Jesús M. Paramio3,Francisco X. Real2,9 and Manuel Serrano1

1Tumor Suppression Group and

2Epithelial Carcinogenesis Group, Spanish National Cancer Research Centre (CNIO), Madrid, Spain.

3Molecular Oncology Unit, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), and Oncogenomic Unit, University Hospital “12 de Octubre,” Madrid, Spain.

4Structural Computational Biology Group,

5Comparative Pathology Unit,

6Monoclonal Antibody Unit, and

7Proteomics Unit, CNIO, Madrid, Spain.

8Intercellular Signaling in Cardiovascular Development and Disease Group, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain.

9Universitat Pompeu Fabra, Barcelona, Spain.

Address correspondence to: Antonio Maraver, Institut de Recherche en Cancérologie de Montpellier (Inserm U1194 – Université Montpellier), ICM Val d’Aurelle, 208 Rue des Apothicaires, F-34298 Montpellier Cedex 5, France. Phone: 33467612395; E-mail:antonio.maraver@inserm.fr. Or to: Manuel Serrano, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, Madrid 28029, Spain. Phone: 34917328000-3430; E-mail: mserrano@cnio.es.

Authorship note: Antonio Maraver and Pablo J. Fernandez-Marcos contributed equally to this work.

Published January 9, 2015
Submitted: July 23, 2014; Accepted: December 4, 2014.

NOTCH signaling suppresses tumor growth and proliferation in several types of stratified epithelia. Here, we show that missense mutations in NOTCH1 and NOTCH2 found in human bladder cancers result in loss of function. In murine models, genetic ablation of the NOTCH pathway accelerated bladder tumorigenesis and promoted the formation of squamous cell carcinomas, with areas of mesenchymal features. Using bladder cancer cells, we determined that the NOTCH pathway stabilizes the epithelial phenotype through its effector HES1 and, consequently, loss of NOTCH activity favors the process of epithelial-mesenchymal transition. Evaluation of human bladder cancer samples revealed that tumors with low levels of HES1 present mesenchymal features and are more aggressive. Together, our results indicate that NOTCH serves as a tumor suppressor in the bladder and that loss of this pathway promotes mesenchymal and invasive features.

Introduction

NOTCH is a single-pass transmembrane receptor activated by interaction with transmembrane ligands of the DSL (Delta-like and Jagged) family present on the membrane of neighboring cells. There are 4 different NOTCH receptors (NOTCH1, -2, -3, and -4) and 5 ligands (JAGGED1 and -2 and DLL1, -3, and -4) in humans. Ligand binding to the extracellular domain of NOTCH induces a cascade of proteolytic cleavages ending with the processing by the γ-secretase complex and the release of the NOTCH intracellular domain. The NOTCH intracellular domain translocates to the nucleus, where it binds the transcription factor RBPJ, and the resulting complex activates the transcription of target genes, notably including transcriptional repressors of the HES and HEY family (1).