Diferentes modelos experimentais têm sido utilizados para estudar a ação trófica do ACTH na supra-renal, e as respostas a esses estímulos parecem ser importantes para proliferação e morte celular in vivo. Essa hipótese foi testada utilizando ratos hipofisectomisados ou tratados com dexametasona, e através da reação de IH avaliamos: 1-a incorporação de BrdU nas diferentes zonas do córtex adrenal estimuladas com ACTH, FGF2 ou N-POMC; 2-se a resposta mitogênica ocorre via receptor MC2R, utilizando um antagonista do ACTH; 3-o número de células do córtex adrenal que entra em apoptose, e se o ACTH recupera o número de células viáveis. Os resultados obtidos mostram que: 1-o ACTH apresenta ação mitogênica nas três zonas do córtex adrenal; 2-a resposta do ACTH ocorre via MC2R; 3-O FGF2 apresenta ação mitogênica apenas nas zonas internas do córtex adrenal; 4-o N-POMC apresenta ação mitogênica na zona glomerulosa; 5-A hipofisectomia induz apoptose nas três zonas do córtex e é prevenida pelo ACTH; 6-a modulação da ciclina E e a CDKIp27 pode estar envolvida na indução do ACTH. / Different experimental models have been used to study the trophic action of ACTH in adrenal, which seems to be important in proliferation and cell death in vivo. This hypothesis was tested using hypophysectomized or dexamethasone treated rats, and through IHC we evaluate: 1-the BrdU incorporation in different adrenal cortex zone after i.p. of ACTH, FGF2 or N-POMC, 2-if the mitogenic response occurs through the MC2R, using for it an antagonist of ACTH, 3-the number of adrenocortical cells which entered into apoptosis, and if ACTH recover this number. The results show that: 1-ACTH is mitogenic in three zone of adrenal cortex; 2-The mitogenic response of ACTH occurs through MC2R; 3-Mitogenic action of FGF2 occurs in the inner zones of adrenal cortex; 4- The N-terminal POMC peptide induces proliferation in the zone glomerulosa; 5- ACTH prevents apoptosis in the adrenal cortex resulting from the surgery, 6- The alteration of cyclin E and CDKI p27 could be a likely molecular mechanism of the effects induced by ACTH.

Avaliou-se os efeitos dos ácidos linoleico e oleico na regeneração do músculo gastrocnêmio lacerado em ratos e em mioblastos, miotubos e fibroblastos em cultura. Houve regeneração incompleta e recuperação parcial da função contrátil do músculo lesionado. O ácido linoleico diminuiu a massa, a atividade contrátil, a área de secção tranversa das fibras, aumentou tecido fibroso no músculo lesionado e elevou a expressão de PCNA, colágeno e fibronectina nos fibroblastos. O ácido oleico aboliu as alterações na atividade contrátil e o aumento de tecido fibroso e elevou a expressão de MyoD em mioblastos e desmina em miotubos e reduziu de PCNA, colágeno e fibronectina em fibroblastos. O ácido linoleico comprometeu a regeneração enquanto que o oleico otimizou a capacidade regenerativa e a função contrátil do músculo lesionado. / The effects of linoleic and oleic acids on regeneration of lacerated gastrocnemius muscle in rats and on cultured myoblasts, myotubes and fibroblasts were examined. There was incomplete regeneration and partial recovery of the contractile function of the injured muscle. Linoleic acid reduced the mass, contratile activity and cross-sectional area of the fibers, raised the fibrous area and reduced the expression of PCNA, collagen and fibronectin in fibroblasts. Oleic acid abolished the changes in contratile activity and the increase in the fibrous area, raised the expressions of MyoD in myoblasts, desmin in myotubes and inhibited the expressions of PCNA, collagen and fibronectin in fibroblasts. Linoleic acid impaired regeneration whereas oleic acid optimized the regenerative capacity and contractile function of the injured muscle.

A cicatrização de feridas crônicas e de defeitos complexos representam desafios para a cirurgia plástica reconstrutiva. Novos tratamentos emergiram com a utilização de células tronco mesenquimais, com especial interesse para as derivadas de tecido adiposo (CTMs-TA), por possuir algumas vantagens em relação às derivadas da medula óssea. Algumas doenças poderiam se beneficiar com o uso das CTMs-TA, em particular, as feridas de pacientes portadores de anemia falciforme que ainda representam um desafio terapêutico. Neste estudo, investigou-se a existência de possíveis áreas doadoras preferenciais de CTMs-TA no tecido adiposo (TA) por meio da comparação de aspectos qualitativos e quantitativos das CTMs-TA derivadas de cinco diferentes áreas corporais. Posteriormente, analisou-se a influência do sobrenadante dessas células, rico em citocinas e fatores de crescimento, sobre a migração de fibroblastos de indivíduos normais e de portadores de anemia falciforme in vitro. Não foram observadas diferenças qualitativas entre as CTMs-TA das cinco áreas analisadas. A região do dorso apresentou número maior de CTMs, com diferença significativa em relação à região das coxas. A adição de sobrenadante produzido por CTMs-TA demonstrou aumento da velocidade de migração dos fibroblastos de forma similar para os normais e os falciformes. O microambiente desfavorável presente nas feridas falciformes parece exercer importante influência sobre esses fibroblastos, pois uma vez corrigido o microambiente com os meios de cultivo apropriados, as células apresentaram taxa de duplicação e velocidade de migração semelhante à dos fibroblastos normais in vitro. / The healing of chronic wounds and complex defects represents challenges for reconstructive plastic surgery. New treatments have emerged with the use of multipotent mesenchymal cells, with special interest for the adipose-derived stem cells (ADSCs) as it has some advantages over the bone marrow-derived. Some diseases could benefit from the use of ADSCs, in particular, the wounds of patients with sickle cell anemia that still represent a therapeutic challenge. In this study, we investigated the existence of possible preferential donor areas of ADSCs in adipose tissue by comparing qualitative and quantitative aspects of ADSCs derived from five different body areas. Later, we analyzed the influence of the supernatant of these cells, rich in cytokines and growth factors, on the migration of fibroblasts from healthy individuals and from patients with sickle cell anemia in vitro. No qualitative differences were observed among the ADSCs of the five areas analyzed. The dorsum presented a higher number of ADSCs, with a significant difference in relation to the thigh. Addition of supernatant produced by ADSCs has been shown to increase the rate of migration of fibroblasts in a similar way to healthy and sickle cells. The unfavorable microenvironment present in sickle wounds seems to exert a significant influence on these fibroblasts because once the microenvironment was corrected with the appropriate culture media, the cells had a doubling rate and migration rate similar to normal fibroblasts in vitro.

Fibroblast growth factor 23 (FGF-23) has recently been shown to be involved in phosphate regulation and bone mineralization. This study evaluated the effect of FGF-23 on three human cell lines (Caco-2, HK-2, SaOS-2) representing three different sites of phosphate regulation (small intestine, kidney proximal tubules, and bone, respectively). FGF-23 induced gene expression was studied using Clontech human Atlas glass microarrays containing various assortments of genes and by a custom designed oligo microarray containing specific genes selected for their biological relevance to FGF-23's potential function. FGF-23 induced differential gene expression in all three cell types, suggesting that FGF-23 may be capable of acting on these three primary sites of phosphate regulation. Human small intestine-like endothelial cell line, Caco-2, showed upregulation of several genes including parathyroid hormone receptors 1 and 2. FGF-23 inhibited the expression of water channel transporters aquaporin 5 and 6 in human osteoblast-like SaOS-2 cells while upregulating aquaporin expression in HK-2 cells. Somatostatin receptors 1-4 were identified to be upregulated in the human kidney, HK-2 cell line. Mucin 2, a gene that is linked to abnormal cellular growth, was consistently induced by FGF-23 in all three cell lines. Families of aquaporins, somatostatins, parathyroid hormones, and other identified differentially expressed genes are involved in different signaling pathways that are associated with phosphate and calcium regulation. Selected candidates were analyzed further by real-time RT-PCR. These data support FGF-23 induced regulation of aquaporin 5 mRNA in HK-2 cells and 1-alpha-hydroxylase mRNA in Caco cells. FGF-23 induced changes in mRNA analysis of four additional genes was less than two-fold in triplicate analysis of selected samples. Taken together, these results suggest that each cell type may have responded to FGF-23, but additional validation of the array data set will be required to identify those genes specifically regulated by FGF-23. Further refinement of this data set will undoubtedly uncover additional functions of FGF-23 and may provide valuable insight into designing therapeutic approaches for phosphate specific disorders.

Avaliou-se os efeitos dos ácidos linoleico e oleico na regeneração do músculo gastrocnêmio lacerado em ratos e em mioblastos, miotubos e fibroblastos em cultura. Houve regeneração incompleta e recuperação parcial da função contrátil do músculo lesionado. O ácido linoleico diminuiu a massa, a atividade contrátil, a área de secção tranversa das fibras, aumentou tecido fibroso no músculo lesionado e elevou a expressão de PCNA, colágeno e fibronectina nos fibroblastos. O ácido oleico aboliu as alterações na atividade contrátil e o aumento de tecido fibroso e elevou a expressão de MyoD em mioblastos e desmina em miotubos e reduziu de PCNA, colágeno e fibronectina em fibroblastos. O ácido linoleico comprometeu a regeneração enquanto que o oleico otimizou a capacidade regenerativa e a função contrátil do músculo lesionado. / The effects of linoleic and oleic acids on regeneration of lacerated gastrocnemius muscle in rats and on cultured myoblasts, myotubes and fibroblasts were examined. There was incomplete regeneration and partial recovery of the contractile function of the injured muscle. Linoleic acid reduced the mass, contratile activity and cross-sectional area of the fibers, raised the fibrous area and reduced the expression of PCNA, collagen and fibronectin in fibroblasts. Oleic acid abolished the changes in contratile activity and the increase in the fibrous area, raised the expressions of MyoD in myoblasts, desmin in myotubes and inhibited the expressions of PCNA, collagen and fibronectin in fibroblasts. Linoleic acid impaired regeneration whereas oleic acid optimized the regenerative capacity and contractile function of the injured muscle.

Como a clorexidina (CHX) tem sido recomendada como solução irrigadora de canais radiculares e como curativo de demora, o objetivo do presente estudo foi caracterizar in vivo a lesão induzida pela injeção de CHX a 0,125, 0,25, 0,5 e 1,0% na pata de camundongos em intervalos de tempo selecionados (24 e 48 horas e 7 e 14 dias) e in vitro o modo e a causa morte celular (necrose e/ou apoptose) e o estresse causado pela exposição de fibroblastos L929 em cultura a concentrações crescentes da droga (0,000125, 0,00025, 0,0005, 0,001, 0,002, 0,004, 0,008 e 0,016%) por 24 horas. A proliferação celular foi avaliada por meio da incorporação de metil-3H-timidina ao DNA das células e imunomarcação para PCNA. A ultraestrutura foi analisada em microscópio eletrônico de transmissão e de varredura e o citoesqueleto das células por meio de marcação para actina e α-tubulina. Citometria de fluxo (Anexina-V FITC/iodeto de propídeo) foi empregada para diferenciar células necróticas de apoptóticas. Também, foi efetuada marcação para retículo endoplasmático, Bcl-2 (B-célula CLL/linfoma 2), Hsp70 (proteína de choque térmico 70) e Grp78 (glucose-regulated protein 78). Quando injetada no espaço subplantar da pata traseira de camundongos, a CHX induziu alterações necróticas na epiderme, derme e tecido subcutâneo em associação com uma resposta inflamatória reacional, particularmente nas concentrações mais elevadas. Em cultura de fibroblastos, a CHX induziu a diminuição da proliferação celular, causou morte celular por apoptose e necrose, desestruturação do citoesqueleto, alteração da morfologia celular, aumento da área das células, dilatação do retículo endoplasmático rugoso e acúmulo de proteínas nas cisternas. Além disso, a CHX causou aumento da expressão de Hsp70, de Grp78 (indicadores de estresse celular) e de Bcl-2 (proteína anti-apoptótica). Em conclusão, a CHX injetada no espaço subplantar da pata traseira de camundongos induz efeitos tóxicos severos. Além disso, a CHX adicionada em cultura de fibroblastos causou estresse do retículo endoplasmático como consequência do acúmulo de proteínas nas cisternas e induziu a morte celular por necrose e apoptose via estresse do retículo endoplasmático, além de causar estresse celular. Os resultados sugerem que a CHX poderia ter um efeito desfavorável na resolução de lesões periapicais em decorrência de sua ação tóxica sobre as células do tecido em torno do ápice dentário. / Because chlorhexidine (CHX) has been recommended as either endodontic irrigant or root canal dressing, this study aimed to characterize in vivo the lesion induced by injection of CHX at concentrations of 0.125, 0.25, 0.5 and 1.0% in the paw of mice at selected time intervals (24 and 48 hours and 7 and 14 days) and in vitro the mode and the cause of cell death (necrosis and /or apoptosis), and the cellular stress caused by exposition of cultured L929 fibroblasts to ascending concentrations of the drug ( 0.000125, 0.00025, 0.0005, 0.001, 0.002, 0.004, 0.008 and 0.016%) for 24 hours. The cell proliferation assay was performed by measuring incorporation of metil-3H-thymidine to cell DNA and immunocytochemical staining analysis of PCNA. The cell ultrastructure was analyzed in transmission and scanning electron microscopes and the cell cytoskeleton by florescence analysis of actin and α- tubulin. Apoptosis and necrosis were discriminated by flow cytometry with annexin V-FITC and PI. In addition endoplasmic reticulum, Bcl-2 (B-cell CLL/lymphoma 2), Hsp70 (heat shock protein 70) and Grp78 (glucoseregulated protein 78) were detected by fluorescence. CHX injected in the sub plantar space of the hind paw of mice induced necrotic changes in the epidermis, dermis and subcutaneous tissue in association with reactive inflammatory response, particularly at higher concentrations. In cultured fibroblasts, CHX decreased cellular proliferation, caused cell death by apoptosis and necrosis, disruption of the cytoskeleton, morphological cellular alterations, increased cells size (area), rough endoplasmic reticulum dilatation with accumulation of cysternal protein. In addition, CHX induced increased expression of Hsp 70, Grp78 (indicators of cellular stress) and Bcl-2 (anti-apoptotic protein). It was concluded that CHX injected in the sub plantar space of the hind paw of mice could induce severe toxic effect. In addition CHX caused endoplasmic reticulum stress as a consequence of accumulation of proteins in the endoplasmic reticulum cysterns and induced cell death by apoptosis and necrosis via endoplasmic reticulum stress and caused cellular stress. Taken together, these findings suggest that CHX may have an unfavorable effect on the resolution of apical periodontitis, due a toxic effect on the periapical tissue cells.

A terapia com laser em baixa intensidade, conhecida como Low-intensity laser therapy (LILT), tem sido alvo de pesquisas que buscam esclarecer os mecanismos pelos quais o laser age na cicatrização de feridas. Este processo é dependente da transmissão de sinais entre epitélio e conjuntivo, os quais influenciam a proliferação e a migração celular, onde participam fatores de crescimento. O objetivo desta pesquisa foi verificar os efeitos da radiação com lasers vermelho e infravermelho em baixa intensidade na produção de fatores de crescimento por fibroblastos in vitro. Foi obtida uma cultura primária de fibroblastos gengivais humanos (linhagem FGH). As células foram cultivadas em placas de 96 poços (5 x 103 células /poço), em estado de quiescência (meio de cultura suplementado com 1% de soro fetal bovino) e irradiadas com lasers de diodo (AlGaAs - 660nm, e AlGaInP - 780nm). O laser em modo contínuo, foi aplicado em contato e na forma pontual. A potência utilizada foi de 40mW numa área de 0,042cm2 e com densidades de energia de 2, 3, 4, 5 e 6J/cm² com respectivos tempos de aplicação de 2, 3, 4, 5 e 6s. As culturas foram irradiadas duas vezes com 6h de intervalo. Os grupos controle positivo e negativo foram cultivados com 10% e 1% de soro fetal bovino, respectivamente e não receberam irradiação. A produção do fator de crescimento de queratinócitos (KGF) e do fator de crescimento de fibroblastos básico (bFGF) foi analisada e quantificada por ensaio imunoenzimático (método ELISA) no meio condicionado pelas células. Os dados foram comparados estatisticamente pela análise de variância e teste de Kruskal-Wallis complementados pelos testes de Tukey e Dunn, respectivamente (p<0,05). Culturas de todos os grupos produziram KGF e bFGF. Controles positivos produziram maior quantidade de KGF e bFGF que controles negativos. A produção de KGF foi similar em todos os grupos experimentais. A produção de bFGF foi significativamente maior nos grupos tratados com o laser infravermelho nas densidades de energia de 3J/cm2 e 5J/cm2 quando comparados com os controles. Baseados nas condições deste estudo, concluiu-se que a LILT não influencia a produção de KGF, porém, influencia positivamente a produção de bFGF de maneira dependente do comprimento de onda e da densidade de energia empregados. O infravermelho, nas densidades de energia de 3J/cm2 e 5J/cm2, é capaz de aumentar a produção deste fator de crescimento. Portanto, a utilização da LILT nestes parâmetros poderá constituir papel relevante na cicatrização de feridas. / Low-intensity laser therapy (LILT) has been the subject of researches to understand the mechanisms by which the laser acts stimulating wound healing. This process is dependent of a signaling transfer between epithelium and connective tissue and it influences cellular proliferation and migration. Growth factors are directly involved in these mechanisms. The aim of this study was to analyze the effects of red and infrared low-level laser on production of fibroblast growth factors by human gingival fibroblasts in vitro. The cells were obtained by primary culture (FGH cell line). They were grown in 96 wells plates (5x10³ cells / well) in a quiescence environment (1% fetal bovine serum) and then they were irradiated with a diode laser (GaAlAs - 660nm, and InGaAlP - 780nm). The continuous laser was applied in contact and in a punctual mode. The power was 40mW, the area of irradiation was 0,042cm2, the energy densities were 2, 3, 4, 5 and 6J/cm² with 2, 3, 4, 5 and 6s of time application, respectively. The cultures were irradiated twice with 6 h-interval. The positive and negative control groups were grown in 10% and 1% of bovine fetal serum, respectively and didn?t receive any irradiation. The production of keratinocyte growth factor (KGF) and basic fibroblast growth factor (bFGF) was analyzed and quantified by immunoenzymatic test (ELISA) in the conditioned medium. The data were compared statistically by analysis of variance and Kruskal-Wallis, complemented by Tukey?s and Dunn?s tests, respectively (p<0,05). Positive controls produced more KGF and bFGF than negative controls. The KGF production was similar in all experimental groups. The bFGF production was significantly higher in groups treated with infrared laser with energy densities of 3J/cm² and 5J/cm² when compared to controls. Based on these study conditions, authors concluded that LILT doesn?t influence KGF production although it positively influences bFGF production in a dependent manner from wavelength and energy density. Infrared laser with energy densities of 3J/cm² and 5J/cm² is capable of improving the production of this growth factor. Therefore the LILT in these parameters can constitute a relevant role on wound healing.

Como a clorexidina (CHX) tem sido recomendada como solução irrigadora de canais radiculares e como curativo de demora, o objetivo do presente estudo foi caracterizar in vivo a lesão induzida pela injeção de CHX a 0,125, 0,25, 0,5 e 1,0% na pata de camundongos em intervalos de tempo selecionados (24 e 48 horas e 7 e 14 dias) e in vitro o modo e a causa morte celular (necrose e/ou apoptose) e o estresse causado pela exposição de fibroblastos L929 em cultura a concentrações crescentes da droga (0,000125, 0,00025, 0,0005, 0,001, 0,002, 0,004, 0,008 e 0,016%) por 24 horas. A proliferação celular foi avaliada por meio da incorporação de metil-3H-timidina ao DNA das células e imunomarcação para PCNA. A ultraestrutura foi analisada em microscópio eletrônico de transmissão e de varredura e o citoesqueleto das células por meio de marcação para actina e &#945;-tubulina. Citometria de fluxo (Anexina-V FITC/iodeto de propídeo) foi empregada para diferenciar células necróticas de apoptóticas. Também, foi efetuada marcação para retículo endoplasmático, Bcl-2 (B-célula CLL/linfoma 2), Hsp70 (proteína de choque térmico 70) e Grp78 (glucose-regulated protein 78). Quando injetada no espaço subplantar da pata traseira de camundongos, a CHX induziu alterações necróticas na epiderme, derme e tecido subcutâneo em associação com uma resposta inflamatória reacional, particularmente nas concentrações mais elevadas. Em cultura de fibroblastos, a CHX induziu a diminuição da proliferação celular, causou morte celular por apoptose e necrose, desestruturação do citoesqueleto, alteração da morfologia celular, aumento da área das células, dilatação do retículo endoplasmático rugoso e acúmulo de proteínas nas cisternas. Além disso, a CHX causou aumento da expressão de Hsp70, de Grp78 (indicadores de estresse celular) e de Bcl-2 (proteína anti-apoptótica). Em conclusão, a CHX injetada no espaço subplantar da pata traseira de camundongos induz efeitos tóxicos severos. Além disso, a CHX adicionada em cultura de fibroblastos causou estresse do retículo endoplasmático como consequência do acúmulo de proteínas nas cisternas e induziu a morte celular por necrose e apoptose via estresse do retículo endoplasmático, além de causar estresse celular. Os resultados sugerem que a CHX poderia ter um efeito desfavorável na resolução de lesões periapicais em decorrência de sua ação tóxica sobre as células do tecido em torno do ápice dentário. / Because chlorhexidine (CHX) has been recommended as either endodontic irrigant or root canal dressing, this study aimed to characterize in vivo the lesion induced by injection of CHX at concentrations of 0.125, 0.25, 0.5 and 1.0% in the paw of mice at selected time intervals (24 and 48 hours and 7 and 14 days) and in vitro the mode and the cause of cell death (necrosis and /or apoptosis), and the cellular stress caused by exposition of cultured L929 fibroblasts to ascending concentrations of the drug ( 0.000125, 0.00025, 0.0005, 0.001, 0.002, 0.004, 0.008 and 0.016%) for 24 hours. The cell proliferation assay was performed by measuring incorporation of metil-3H-thymidine to cell DNA and immunocytochemical staining analysis of PCNA. The cell ultrastructure was analyzed in transmission and scanning electron microscopes and the cell cytoskeleton by florescence analysis of actin and &#945;- tubulin. Apoptosis and necrosis were discriminated by flow cytometry with annexin V-FITC and PI. In addition endoplasmic reticulum, Bcl-2 (B-cell CLL/lymphoma 2), Hsp70 (heat shock protein 70) and Grp78 (glucoseregulated protein 78) were detected by fluorescence. CHX injected in the sub plantar space of the hind paw of mice induced necrotic changes in the epidermis, dermis and subcutaneous tissue in association with reactive inflammatory response, particularly at higher concentrations. In cultured fibroblasts, CHX decreased cellular proliferation, caused cell death by apoptosis and necrosis, disruption of the cytoskeleton, morphological cellular alterations, increased cells size (area), rough endoplasmic reticulum dilatation with accumulation of cysternal protein. In addition, CHX induced increased expression of Hsp 70, Grp78 (indicators of cellular stress) and Bcl-2 (anti-apoptotic protein). It was concluded that CHX injected in the sub plantar space of the hind paw of mice could induce severe toxic effect. In addition CHX caused endoplasmic reticulum stress as a consequence of accumulation of proteins in the endoplasmic reticulum cysterns and induced cell death by apoptosis and necrosis via endoplasmic reticulum stress and caused cellular stress. Taken together, these findings suggest that CHX may have an unfavorable effect on the resolution of apical periodontitis, due a toxic effect on the periapical tissue cells.

Le mélanome est le cancer de la peau le plus dangereux : il est capable de métastaser rapidement vers les ganglions et les viscères, et est réfractaire aux chimio/radiothérapies. De nouvelles thérapies ciblant la kinase BRAFV600 retrouvée dans 60% des mélanomes ont montré des effets spectaculaires en termes de survie globale et sans progression de la maladie. L’efficacité de ces thérapies est compromise par l’apparition fréquente de résistances. Les cellules cancéreuses sont ancrées au sein d’un microenvironnement avec lequel elles interagissent. Elles profitent de facteurs solubles du stroma et de l’adhésion à la matrice extracellulaire (MEC) pour survivre face aux thérapies. La protéine matricellulaire SPARC orchestre les interactions entre les cellules saines ou cancéreuses et leur microenvironnement. Absente dans les mélanocytes, son expression est initiée et augmentée dans les mélanomes, corrélée à la progression tumorale et à un mauvais pronostic clinique. Lorsqu’elle est sécrétée par les cellules de mélanome, elle active la kinase AKT, déstabilise le suppresseur de tumeur p53 et favorise la prolifération/survie tumorale. Nous avons montré que le module SPARC/AKT est un nouveau déterminant de la résistance innée ou acquise des mélanomes mutés BRAFV600 aux anti-BRAF, et mis en évidence l’intérêt du ciblage de SPARC en combinaison avec des anti-BRAF ou -MEK pour optimiser/restaurer la sensibilité des mélanomes à ces inhibiteurs. Nous avons aussi montré que les fibroblastes ganglionnaires ont des caractéristiques de fibroblastes activés, et confèrent une résistance aux anti-BRAF aux cellules de mélanomes en générant une MEC permissive à laquelle elles adhérent. / Melanoma is the most dangerous form of skin cancer due to its high metastatic potential and its resistance to both classical chemo- and radiotherapies. New targeted therapies directed against the V600E oncogenic form of BRAF found in about 60% of patients have demonstrated spectacular efficacy both in terms of progression free and overall survival. However most patients invariably relapse after a few months due to resistance mechanisms. Cancer cells are anchored and interact constantly with their microenvironment. Both soluble factors and the extracellular matrix produced by stromal cells have been shown to contribute to cancer cell resistance to therapies. SPARC is a matricellular protein that orchestrates interactions between normal and/or cancer cells and their microenvironment. While it is absent in melanocytes, SPARC expression increases in melanoma and is correlated with both tumoral progression and a bad prognosis. When SPARC is secreted by melanoma cells, it activates the AKT kinase, destabilizes the p53 tumor suppressor and promotes proliferation and survival. Here we identify the couple SPARC/AKT as a new actor contributing to both innate and acquired resistance to BRAFV600E inhibitors. In addition, we demonstrate that targeting SPARC in melanoma cells increases their sensitivity to both BRAF and MEK inhibitors. Finally we show that lymph node fibroblasts share features of activated fibroblasts and confer resistance to BRAF inhibitors to melanoma cells through the production of a permissive extracellular matrix.

La maladie de Parkinson (MP) est une pathologie neurodégénérative fréquente. Différents mécanismes moléculaires ont été mis en cause, dont une dysfonction mitochondriale. Des mutations du gène LRRK2, codant la protéine leucine-rich repeat kinase 2, sont responsables de formes autosomiques dominantes. La substitution la plus fréquente, G2019S, confère à la protéine un gain de fonction. LRRK2 semble réguler l’homéostasie mitochondriale, rôle initialement attribué aux protéines Parkine et PINK1, qui régulent en particulier la mitophagie. Nous avons étudié le rôle de LRRK2 et de son variant LRRK2-G2019S dans la régulation de la mitophagie dépendante de PINK1/Parkine. Nous avons également évalué l’effet de l’activité kinase sur ce processus dans un modèle cellulaire et dans des fibroblastes de patients. Nous avons exploré l’effet de LRRK2 sur la régulation d’interactions protéiques essentielles dans la mitophagie. Enfin, nous avons comparé l’efficacité de la mitophagie dans les formes familiales de la MP liées aux gènes LRRK2 et PARK2. Nous avons montré que LRRK2 et son variant LRRK2 G2019S retardent la mitophagie. Au travers de son activité kinase, LRRK2 compromet des interactions protéiques clefs impliquant Parkine et la GTPase Drp1. Nous avons mis en évidence un défaut de ce processus dans les fibroblastes de patients porteurs de mutations du gène PARK2. Ce défaut est également retrouvé dans les fibroblastes de patients porteurs de la substitution G2019S, dans lesquels il est corrigé par l’inhibition de l’activité kinase de la protéine. Ces résultats mettent en évidence un rôle de LRRK2 et de sa substitution pathogène dans la mitophagie dépendante de la voie PINK1/Parkine. / Parkinson’s disease (PD) is a frequent neurodegenerative disorder. Different molecular mechanisms are suspected, among which mitochondrial dysfunction stands out. Mutations in LRRK2, encoding leucine-rich repeat kinase 2 (LRRK2), cause autosomal dominant PD forms. The most frequent G2019S substitution leads to a gain of function. LRRK2 seems to modulate mitochondrial homeostasis, initially associated with Parkin and PINK1 proteins, which regulate in particular mitophagy. Here, we explored the involvement of LRRK2 and its kinase activity in the regulation of PINK1/Parkin-dependent mitophagy, and evaluated the consequence of the G2019S substitution, both in a cell line (COS7) and in primary fibroblasts from PD patients. In particularly, we studied the impact of LRRK2 on the regulation of protein-protein interactions essential for mitophagy initiation. We also compared the efficiency of PINK1/Parkin-dependent mitochondrial clearance in familial PD forms linked to LRRK2 and PARK2. Our results show that LRRK2 and its LRRK2 G2019S variant delay mitophagy. Moreover, these proteins compromised key interactions involving Parkin and the GTPase dynamin related protein 1 (Drp1) on the outer mitochondrial membrane. We confirmed a defect in this process in fibroblasts from patients with PARK2 mutations and found a similar alteration in fibroblasts from patients with the G2019S substitution. Inhibition of LRRK2 kinase activity restored mitophagy induction in cells from LRRK2 patients, but not in cells from PARK2 patients. Altogether, these results highlight a role of LRRK2 and its pathogenic substitution in the regulation of PINK1/Parkin-dependent mitophagy.