Le lumicanne est un petit protéoglycanne riche en leucine de la matrice extracellulaire impliqué, entre autre, dans le contrôle de l'angiogenèse, en particulier l'angiogenèse tumorale. Nous avons déjà démontré que le lumicanne inhibe la progression du mélanome in vivo. Le mécanisme d'action anti-tumoral du lumicanne a été partiellement décrit dans notre laboratoire. L'intégrine alpha2beta1 a été caractérisée comme un récepteur direct du lumicanne. Dans l'étude que nous présentons, nous avons décrit le rôle du lumicanne dans le contrôle de la transition des cellules souche mésenchymateuse (CSM) en cellules progénitrices endothéliales, pouvant contribuer à l'angiogenèse tumorale. Nous avons montré que le lumicanne inhibe spécifiquement la migration et l'invasion des CSM par une diminution de l'expression et de l'activité de la MMP-14. De plus, nous avons démontré que le lumicanne est un inhibiteur compétitif de la MMP-14. Il se lie directement au domaine catalytique de l'enzyme avec une affinité modérée (KD=275,4±16.12nM). De plus, nous avons démontré que le lumicanne diminue la phosphorylation de récepteurs (EGFR, Mer, EphB2, EphB6, ROR) et de protéines kinases (AKT, GSK3 beta et p130CAS). Une diminution de l'expression de la beta-caténine a également été détectée.Notre équipe a précédemment identifié une séquence de 17aa dans la protéine de cœur du lumicanne, la lumcorine, qui est capable de reproduire l'effet anti-migratoire du lumicanne. Nous proposons ici deux mécanismes d'action de la lumcorine: une inhibition de la phosphorylation de FAK et une diminution de l'activité de la MMP-14. De plus, nous avons identifié, au sein de la séquence de la lumcorine, un peptide court de 10aa (L9M) qui est capable de reproduire l'effet anti-tumoral de la lumcorine. Nous montrons que le peptide cyclique L9M diminue la croissance tumorale in vivo.Nos travaux permettent donc de mieux comprendre les mécanismes impliqués dans l'effet anti-tumoral du lumicanne et mettent en évidence de nouveaux peptides prometteurs pour des applications anticancéreuses. / Lumican is a small leucine-rich proteoglycan of the extracellular matrix involved in the control of angiogenesis, particularly tumor angiogenesis. We have previously demonstrated that lumican inhibits melanoma progression in vivo. The anti-tumor mechanism of action of lumican was partially described in our laboratory. The alpha2beta1 integrin was characterized as a direct receptor of lumican. In the present studies, we first described the role of lumican in the control of Mesenchymal Stem Cells (MSC) transition to functional Endothelial Progenitor Cells (EPC), which can contribute to tumor angiogenesis. We showed that lumican inhibits specifically the migration and invasion of MSC by decreasing the expression and activity of MMP-14. Moreover, we demonstrated that lumican reduces the activity of MMP-14 in melanoma cells. We next showed that lumican directly inhibits MMP-14 activity as a competitive inhibitor which binds to the catalytic domain of the enzyme with moderate affinity (KD=275.4±16.12nM). Moreover, we demonstrated that lumican decreases the phosphorylation of some cell surface receptors (EGFR, Mer, EphB2, EphB6, ROR), some kinases (AKT, GSK3 beta and p130CAS) and alters the expression of beta-catenin.Previous works from our laboratory identified a sequence of 17aa within the leucine-rich repeat 9, named lumcorin, which was able to reproduce the anti-migratory effect of lumican. Here, we propose two mechanisms of action of lumcorin: inhibition of phosphorylation of FAK and a decrease of the MMP-14 activity. We also identified in the sequence of lumcorin a short 10aa peptide (L9M) which was capable to reproduce the anti-tumor effect of lumcorin. In addition, the cyclic peptide L9M was demonstrated to reduce tumor growth in vivo.Altogether, our results help to better understand the mechanisms involved in the anti-tumor effect of lumican and identify lumican-derived peptides which could have potential anti-cancer applications.

CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / As metaloproteinases-2 (MMP-2) e -14 (MMP-14) e o inibidor tecidual de metaloproteinases tipo 2 (TIMP-2) participam de modo fundamental na transiÃÃo epitelial-mesenquimal e progressÃo tumoral-linfonodal de muitos tipos de cÃncer, inclusive o gÃstrico. O objetivo deste trabalho à avaliar a expressÃo das trÃs enzimas no carcinoma gÃstrico e metÃstases linfonodais e suas possÃveis participaÃÃes na progressÃo tumoral. Foram utilizados 83 casos de gastrectomias por cÃncer gÃstrico (histotipo intestinal = 53 casos; difuso = 30 casos), e seus respectivos linfonodos, dos arquivos do Departamento de Patologia e Medicina Legal/UFC. Foi realizado tissue microarray e imunohistoquÃmica com anticorpo monoclonal anti-MMP-2, anti-MMP-14 e anti-TIMP-2, avaliada atravÃs dos seguintes escores: 0 = ausÃncia de imunomarcaÃÃo ou raras cÃlulas marcadas (< 5%); 1 = marcaÃÃo discreta na maioria (> 50%) das cÃlulas tumorais ou inflamatÃrias mononucleadas (muitos dos quais identificados como macrÃfagos pelo CD68) ou marcaÃÃo moderada em minoria de cÃlulas (< 50%); 2 = marcaÃÃo moderada na maioria (> 50%) das cÃlulas tumorais ou inflamatÃrias mononucleadas ou marcaÃÃo intensa em minoria de cÃlulas (< 50%); 3 = marcaÃÃo intensa na maioria (> 50%) das cÃlulas tumorais ou inflamatÃrias mononucleadas. A expressÃo de MMP-2, MMP-14 e TIMP-2 nos mononucleares associados a tumores ocorreu com maior frequÃncia comparada à imunomarcaÃÃo em mononucleares da mucosa normal, com diferenÃa significativa em relaÃÃo a TIMP-2 (40/53 vs 12/26; *p = 0,0128, teste exato de Fisher). MMP-2 foi muito mais presente nas mulheres (p = 0,0248) enquanto TIMP-2 ocorreu predominantemente apÃs os 50 anos (p = 0,0034). A expressÃo dos trÃs biomarcadores nos carcinomas gÃstricos primÃrios foi muito superior nos mononucleares, em relaÃÃo Ãs cÃlulas neoplÃsicas, sobretudo para a MMP-2 (16/46 vs 5/46; *p = 0,0118), que tambÃm prevaleceu em mononucleares das metÃstases linfonodais em tumores dos histotipos intestinal e difuso (13/16 vs 4/19; ***p = 0,0006). Neste estudo, a expressÃo preponderante dos trÃs imunomarcadores pelos mononucleares do conjuntivo reforÃa o papel central destas cÃlulas e do microambiente tumoral na progressÃo do cÃncer gÃstrico. A maior expressÃo de TIMP-2 no sÃtio primÃrio à sugestiva do efeito inibitÃrio desta enzima sobre MMP-2 e MMP-14, que parecem participar principalmente em fases mais avanÃadas da progressÃo tumoral-linfonodal. A MMP-14, atravÃs dos mononucleares, parece estar mais envolvida na progressÃo do cÃncer gÃstrico difuso do que a MMP-2 e seu inibidor tissular.

No / A major drawback with current cancer therapy is the prevalence of unrequired doselimiting toxicity to non-cancerous tissues and organs, which is further compounded by a limited ability to rapidly and easily monitor drug delivery, pharmacodynamics and therapeutic response. In this report, the design and characterization of novel multifunctional “theranostic” nanoparticles (TNPs) is described for enzyme-specifi c drug activation at tumor sites and simultaneous in vivo magnetic resonance imaging (MRI) of drug delivery. TNPs are synthesized by conjugation of FDA-approved iron oxide nanoparticles ferumoxytol to an MMP-activatable peptide conjugate of azademethylcolchicine (ICT), creating CLIOICTs (TNPs). Signifi cant cell death is observed in TNP-treated MMP-14 positive MMTVPyMT breast cancer cells in vitro, but not MMP-14 negative fi broblasts or cells treated with ferumoxytol alone. Intravenous administration of TNPs to MMTV-PyMT tumor-bearing mice and subsequent MRI demonstrates signifi cant tumor selective accumulation of the TNP, an observation confi rmed by histopathology. Treatment with CLIO-ICTs induces a significant antitumor effect and tumor necrosis, a response not observed with ferumoxytol. Furthermore, no toxicity or cell death is observed in normal tissues following treatment with CLIO-ICTs, ICT, or ferumoxytol. These fi ndings demonstrate proof of concept for a new nanotemplate that integrates tumor specifi city, drug delivery and in vivo imaging into a single TNP entity through attachment of enzyme-activated prodrugs onto magnetic nanoparticles. This novel approach holds the potential to signifi cantly improve targeted cancer therapies, and ultimately enable personalized therapy regimens. / Yorkshire Cancer Research