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11 páginas, 8 figuras, 2 tablas.-- et al. ; Germline activation of H-RAS oncogenes is the primary cause of Costello syndrome (CS), a neuro-cardio-facio-cutaneous developmental syndrome. Here we describe the generation of a mouse model of CS by introduction of an oncogenic Gly12Val mutation in the mouse H-Ras locus using homologous recombination in ES cells. Germline expression of the endogenous H-RasG12V oncogene, even in homozygosis, resulted in hyperplasia of the mammary gland. However, development of tumors in these mice was rare. H-RasG12V mutant mice closely phenocopied some of the abnormalities observed in patients with CS, including facial dysmorphia and cardiomyopathies. These mice also displayed alterations in the homeostasis of the cardiovascular system, including development of systemic hypertension, extensive vascular remodeling, and fibrosis in both the heart and the kidneys. This phenotype was age dependent and was a consequence of the abnormal upregulation of the renin-Ang II system. Treatment with captopril, an inhibitor of Ang II biosynthesis, prevented development of the hypertension condition, vascular remodeling, and heart and kidney fibrosis. In addition, it partially alleviated the observed cardiomyopathies. These mice should help in elucidating the etiology of CS symptoms, identifying additional defects, and evaluating potential therapeutic strategies. ; This work was supported by grants from the Spanish Ministry of Education and Science to M. Barbacid (SAF2003-05172 and SAF2004-20477-E) and X.R. Bustelo (SAF2006-01789); from the VI Framework Programme of the European Union to M. Barbacid (LSHC-CT-2004-503438, LSHG-CT-2007-037665, and LSHGCT-2006-037188); from the National Cancer Institute, NIH, to X.R. Bustelo (5R01-CA73735-10); from the Fondo de Investigación Sanitaria to C. Guerra (PI042124); from the Red Temática de Investigación Cooperativa en Cáncer, Instituto de Salud Carlos III, to X.R. Bustelo (RD06/0020/0001); from the Autonomous Community of Madrid to M. Barbacid (GR/SAL/0587/2004) and C. Guerra (GR/SAL/0349/2004); from the Autonomous Government of Castilla-León to X.R. Bustelo (SA053A05); and from the Fundación de la Mutua Madrileña de Automóviles to M. Barbacid. All Spanish funding to X.R. Bustelo is cosponsored by the European Union FEDER program. A.J. Schuhmacher is supported by a FPU fellowship from the Spanish Ministerio de Educación y Ciencia (MEC). V. Sauzeau is partially supported by a Juan de la Cierva postdoctoral contract from the MEC. ; Peer Reviewed

Background A critical challenge in the management of Glioblastoma Multiforme (GBM) tumors is the accurate diagnosis and assessment of tumor progression in a noninvasive manner. We have identified Membrane-type 1 matrix metalloproteinase (MT1-MMP) as an attractive biomarker for GBM imaging since this protein is actively involved in tumor growth and progression, correlates with tumor grade and is closely associated with poor prognosis in GBM patients. Here, we report the development of an immunoPET tracer for effective detection of MT1-MMP in GBM models. Methods An anti-human MT1-MMP monoclonal antibody (mAb), LEM2/15, was conjugated to p-isothiocyanatobenzyl-desferrioxamine (DFO-NCS) for Zr-89 labeling. Biodistribution and PET imaging studies were performed in xenograft mice bearing human GBM cells (U251) expressing MT1-MMP and non-expressing breast carcinoma cells (MCF-7) as negative control. Two orthotopic brain GBM models, patient-derived neurospheres (TS543) and U251 cells, with different degrees of blood-brain barrier (BBB) disruption were also used for PET imaging experiments. Results Zr-89 labeling of DFO-LEM2/ 15 was achieved with high yield (>90\%) and specific activity (78.5 MBq/mg). Biodistribution experiments indicated that Zr-89-DFO-LEM2/15 showed excellent potential as a radiotracer for detection of MT1-MMP positive GBM tumors. PET imaging also indicated a specific and prominent Zr-89-DFO-LEM2/15 uptake in MT1-MMP+ U251 GBM tumors compared to MT1-MMP-MCF-7 breast tumors. Results obtained in orthotopic brain GBM models revealed a high dependence of a disrupted BBB for tracer penetrance into tumors. Zr-89-DFO-LEM2/15 showed much higher accumulation in TS543 tumors with a highly disrupted BBB than in U251 orthotopic model in which the BBB permeability was only partially increased. Histological analysis confirmed the specificity of the immunoconjugate in all GBM models. Conclusion A new anti MT1-MMP-mAb tracer, Zr-89-DFO-LEM2/15, was synthesized efficiently. In vivo validation showed high-specific-contrast imaging of MT1-MMP positive GBM tumors and provided strong evidence for utility of MT1-MMP-targeted immunoPET as an alternate to nonspecific imaging of GBM. ; MAM JLMT AJS FMA: Crowdfunding platform ``Precipita´´ FECYT (Spanish Foundation for Science and Technology) [http://www.precipita.es/precipitado/deteccion-y-seguimiento-del-cance r-cerebral-mas-comun-y-danino.html]. AGA JLMT: Regional Government of Madrid Angiobodies Programme S2010/BMD-2312 [http://www.madrid.org/cs/Satellite?buscador=true\&c=CM\_ConvocaPresta c\_FA\&cid=1142619643182\&language=es\&pagename=ComunidadMadrid\%2FEstru ctura]. AJS: BBVA Foundation grant for Research, Innovation and Cultural Creation and M+Vision Advanced fellowship. MS: Marie Curie CIG grant \& Seve Ballesteros Foundation grant. ; Sí