Role of the functional interface LRP-1/integrin beta1 in tumor progression

Résumé : LRP-1 est un récepteur d’endocytose qui fut d’abord associé à des propriétés anti-tumorales via l’internalisation et le catabolisme de protéases matricielles. Cependant, malgré ses capacités à limiter le remodelage de la matrice extracellulaire, LRP-1 peut également coordonner la balance adhérence/dé-adhérence des cellules tumorales afin de favoriser l’invasion. LRP-1 fonctionne ainsi en régulant l’organisation du cytosquelette et le renouvellement des structures d’adhérence grâce à l’activation de la voie MEK/ERK et l’inhibition concomitante de la voie MKK7/JNK. Au cours de ce travail, nous avons cherché à déterminer comment LRP-1 peut réguler le protéome membranaire des cellules tumorales. Nos données révèlent que le taux d’intégrine β1 à la surface de carcinome thyroïdien FTC-133 est augmenté en présence de RAP, un antagoniste de LRP-1. Des immunoprécipitations et des analyses par imagerie confocale montrent que LRP-1 et l’intégrine β1 coexistent au sein des mêmes complexes biomoléculaires. Des tests d’endocytose démontrent que LRP-1 constitue un récepteur d’endocytose de l’intégrine β1 dans les FTC 133 car le nombre d’endosomes contenant l’intégrine β1 est diminué de 30% quand l’endocytose dépendante de LRP-1 est inhibée. Par ailleurs, nos données indiquent que LRP-1 est principalement impliqué dans le recyclage de l’intégrine β1 mais pas dans son ciblage au lysosome. Nous avons ainsi identifié une relation moléculaire privilégiée et originale entre LRP-1 et l’intégrine β1 dans le contexte tumoral. Ces travaux nous ont également incités à initier le développement d’un traceur bimodal original (fluorescence/Raman) permettant de suivre l’endocytose dépendante de LRP 1.LRP-1 is a large multifunctional endocytic receptor first associated to anti-tumor properties by carrying the uptake and catabolism of extracellular matrix-associated proteinases. However, despite its ability to limit extracellular matrix remodeling, LRP-1 may also coordinate the adhesion/deadhesion balance in malignant cells to support invasion. LRP-1 acts so by regulating the cytoskeleton organization and adhesion structure turnover through the activation of MEK/ERK and concomitant inhibition of MKK7/JNK pathway.During this study, we investigated how LRP-1 is able to regulate the cell-surface proteome in malignant cells. Our data revealed that β1-integrin level is significantly increased at the cell surface of FTC-133 thyroid carcinoma upon treatment with RAP, used as LRP-1 antagonist. Immunoprecipitation experiments and confocal analysis highlight that LRP-1 and β1 integrin coexist at the same biomolecular complexes. Biochemical endocytosis assays demonstrate LRP-1 as a mediator of β1-integrin endocytosis in FTC-133 because the number of endosomes-containing β1-integrin decreases by 30% when LRP-1-mediated endocytosis is inhibited. Moreover, our data indicate that LRP-1 is mainly involved in β1-integrin recycling, but not in lysosome targeting.Overall, we identified an original molecular way between LRP-1 and β1-integrin in the tumor context. These works also allowed to initiate the development of an original bimodal molecular tracker (using both fluorescence and Raman) to study LRP-1-mediated endocytosis

Identification of LRP-1 as an endocytosis and recycling receptor for B1-integrin in thyroid cancer cells

International audienceLRP-1 is a large endocytic receptor mediating the clearance of various molecules from the extracellular matrix. LRP-1 was reported to control focal adhesion turnover to optimize the adhesion-deadhesion balance to support invasion. To better understand how LRP-1 coordinates cell-extracellular matrix interface, we explored its ability to regulate cell surface integrins in thyroid carcinomas. Using an antibody approach, we demonstrated that β1-integrin levels were increased at the plasma membrane under LRP1 silencing or upon RAP treatment, used as LRP-1 antagonist. Our data revealed that LRP-1 binds with both inactive and active β1-integrin conformations and identified the extracellular ligand-binding domains II or IV of LRP-1 as sufficient to bind β1-integrin. Using a recombinant β1-integrin, we demonstrated that LRP-1 acts as a regulator of β1-integrin intracellular traffic. Moreover, RAP or LRP-1 blocking antibodies decreased up to 36% the number of β1-integrin-containing endosomes. LRP-1 blockade did not significantly affect the levels of β1-integrin-containing lysosomes while decreasing localization of β1-integrin within Rab-11 positive vesicles. Overall, we identified an original molecular process in which LRP-1 acts as a main regulator of β1-integrin internalization and recycling in thyroid cancer cells

Identification of TAX2 peptide as a new unpredicted anti-cancer agent

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SPAT: Surface Protein Annotation Tool

Given the particular attractivity of antibody-based immunotherapies, in vitro experimental approaches aiming to identify and quantify proteins directly located at the cell surface, such as the surfaceome, have been recently developed and improved. However, the “surface” enriched, yet noisy output obtained from available methods makes it challenging to accurately evaluate which proteins are more likely to be located at the surface of the plasma membrane and which are simple contaminants. To that purpose, we developed the in silico Surface Protein Annotation Tool (SPAT), which unifies established annotations to grade proteins according to the chance they have to be located at the cell surface. SPAT accuracy was tested using in-house acute myeloid leukemia data, as well as public datasets, and despite using publicly available annotations, showed good performances when compared to more complex surfaceome predictors. Given its simple input requirement, SPAT is easily usable for the annotation of any gene/protein lists. Its output, in addition to the “surface” score, provides additional annotations including a “secretion” flag, references to verified antibodies targeting annotated proteins, as well as expression data and protein levels in essential human organs, making it a user-friendly tool for the community

Immunotherapeutic targeting of surfaceome heterogeneity in AML

Summary: Immunotherapy remains underexploited in acute myeloid leukemia (AML) compared to other hematological malignancies. Currently, gemtuzumab ozogamicin is the only therapeutic antibody approved for this disease. Here, to identify potential targets for immunotherapeutic intervention, we analyze the surface proteome of 100 genetically diverse primary human AML specimens for the identification of cell surface proteins and conduct single-cell transcriptome analyses on a subset of these specimens to assess antigen expression at the sub-population level. Through this comprehensive effort, we successfully identify numerous antigens and markers preferentially expressed by primitive AML cells. Many identified antigens are targeted by therapeutic antibodies currently under clinical evaluation for various cancer types, highlighting the potential therapeutic value of the approach. Importantly, this initiative uncovers AML heterogeneity at the surfaceome level, identifies several antigens and potential primitive cell markers characterizing AML subgroups, and positions immunotherapy as a promising approach to target AML subgroup specificities

Descriptive epidemiology of 399 histologically confirmed newly diagnosed meningeal solitary fibrous tumours and haemangiopericytomas in France: 2006–2015

International audiencePurpose: Meningeal solitary fibrous tumour (SFT) and haemangiopericytoma (HPC) are uncommon tumours that have been merged into a single entity in the last 2021 WHO Classification of Tumors of the Central Nervous System. To describe the epidemiology of SFT/HPC operated in France and, to assess their incidence.Methods: We processed the French Brain Tumour Database (FBTDB) to conduct a nationwide population-based study of all histopathologically confirmed SFT/HPC between 2006 and 2015.Results: Our study included 399 SFT/HPC patients, operated in France between 2006 and 2015, in one of the 46 participating neurosurgical centres. The incidence reached 0.062, 95%CI[0.056-0.068] for 100,000 person-years. SFT accounted for 35.8% and, HPC for 64.2%. The ratio of SFT/HPC over meningioma operated during the same period was 0.013. SFT/HPC are about equally distributed in women and men (55.9% vs. 44.1%). For the whole population, mean age at surgery was 53.9 (SD ± 15.8) years. The incidence of SFT/HPC surgery increases with the age and, is maximal for the 50-55 years category. Benign SFT/HPC accounted for 65.16%, SFT/HPC of uncertain behaviour for 11.53% and malignant ones for 23.31%. The number of resection progresses as the histopathological behaviour became more aggressive. 6.7% of the patients with a benign SFT/HPC had a second surgery vs.16.6% in case of uncertain behaviour and, 28.4% for malignant SFT/HPC patients.Conclusion: Meningeal SFT and HPC are rare CNS mesenchymal tumours which both share common epidemiological characteristics, asserting their merging under a common entity. SFT/HPC incidence is less that one case for 1 billion per year and, for around 100 meningiomas-like tumours removed, one SFT/HPC may be diagnosed. SFT/HPC are equally distributed in women and men and, are mainly diagnosed around 50-55 years. The more aggressive the tumour, the higher the probability of recurrence

Descriptive epidemiology of 30,223 histopathologically confirmed meningiomas in France: 2006–2015

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