O carcinoma espinocelular (CEC) de cabeça e pescoço é uma neoplasia maligna de prognóstico desfavorável e baixa taxa de sobrevida. Entender os processos biológicos envolvidos na carcinogênese poderá ser de extrema importância para o desenvolvimento de novas tecnologias de tratamento e melhora do prognóstico em pacientes acometidos pela doença. A maior causa de insucessos clínicos em termos de terapia e prognóstico em pacientes com câncer é a invasão tecidual e o desenvolvimento de potencial metastático. A migração celular é indispensável para a progressão tumoral e as células apresentam motores moleculares desempenhados especialmente pela família da Miosina II não muscular (MNMII). Codificadas por diferentes genes, existem três isoformas conhecidas em células de mamíferos (MNMIIA, MNMIIB, MNMIIC). As MNMIIs estão envolvidas em funções celulares como migração, adesão e citocinese. Sendo o entendimento da migração, adesão celular e citocinese fatores chave na progressão tumoral, e que o a invasão tecidual e o desenvolvimento de potencial metastático são essenciais na definição do prognóstico dos pacientes, o objetivo deste estudo foi descrever o perfil e exposição à fatores de risco como álcool e fumo dos pacientes diagnosticados com CEC de cabeça e pescoço, graduação histológica, parâmetros clínicos tumorais (TNM), padrão de expressão das isoformas de MNMII (MNMIIA, MNMIIB, MNMIIC) no centro do tumor, zona de invasão e tecido epitelial não neoplásico adjacente ao tumor, relacionando a expressão e localização dessas proteínas com os dados descritos bem como evolução dos pacientes após 5 anos de acompanhamento. De acordo com os resultados sugere-se que a MNMIIB expressa no EA possa indicar o potencial de metástase regional do CEC e a MNMIIC presente na zona de invasão tumoral (ZI) seja um fator predictor de prognóstico ruim da doença. Sendo assim, é possível propor que a avaliação de imunorreatividade da MNMIIB no EA e MNMIIC na ZI seja utilizada na análise das peças operatórias, como complemento à análise morfológica de rotina. / Squamous cell carcinoma (SCC) of the head and neck is a malignant neoplasm of poor prognosis and low survival rate. Understand the biological processes involved in carcinogenesis can be extremely important for the development of new treatment technologies and improved prognosis in patients affected by the disease. The major cause of clinical failure in terms of therapy and prognosis in cancer patients is the development of tissue invasion and metastatic potential. Cell migration is essential for tumor progression and the cells have molecular motors especially formed from non-muscular myosin II family (NMMII). Encoded by different genes, there are three known isoforms in mammalian cells (NMMIIA, NMMIIB, NMMIIC). The NMMIIs are involved in cellular functions such as migration, adhesion, and cytokinesis. As the understanding of migration, cell adhesion and cytokinesis key factors in tumor progression, and that the tissue invasion and metastatic potential for development are essential in defining the prognosis of patients, the objective of this study was to describe the profile and exposure to risk factors such as alcohol and tobacco of patients diagnosed with head and neck SCC, histological grading, tumor clinical parameters (TNM), pattern of expression of isoforms NMMII (NMMIIA, NMMIIB, NMMIIC) in the center of the tumor (CT), tumor invasion zone area and not neoplastic adjacent to the tumor (AE), relating the expression and localization of these proteins with the data described and outcome of patients after 5 years of follow-up. According to the results it is suggested that the NMMIIB expressed in AE may indicate the potential regional metastasis of SCC and NMMIIC present in the tumor invasion zone (IZ) is a predictor factor of poor prognosis of the disease. Therefore, it is possible to propose that immunoreactivity assessment of NMMIIB in EA and NMMIIC in IZ could be used in the analysis of operative parts, as a complement to routine morphological analysis.

O carcinoma espinocelular (CEC) de cabeça e pescoço é uma neoplasia maligna de prognóstico desfavorável e baixa taxa de sobrevida. Entender os processos biológicos envolvidos na carcinogênese poderá ser de extrema importância para o desenvolvimento de novas tecnologias de tratamento e melhora do prognóstico em pacientes acometidos pela doença. A maior causa de insucessos clínicos em termos de terapia e prognóstico em pacientes com câncer é a invasão tecidual e o desenvolvimento de potencial metastático. A migração celular é indispensável para a progressão tumoral e as células apresentam motores moleculares desempenhados especialmente pela família da Miosina II não muscular (MNMII). Codificadas por diferentes genes, existem três isoformas conhecidas em células de mamíferos (MNMIIA, MNMIIB, MNMIIC). As MNMIIs estão envolvidas em funções celulares como migração, adesão e citocinese. Sendo o entendimento da migração, adesão celular e citocinese fatores chave na progressão tumoral, e que o a invasão tecidual e o desenvolvimento de potencial metastático são essenciais na definição do prognóstico dos pacientes, o objetivo deste estudo foi descrever o perfil e exposição à fatores de risco como álcool e fumo dos pacientes diagnosticados com CEC de cabeça e pescoço, graduação histológica, parâmetros clínicos tumorais (TNM), padrão de expressão das isoformas de MNMII (MNMIIA, MNMIIB, MNMIIC) no centro do tumor, zona de invasão e tecido epitelial não neoplásico adjacente ao tumor, relacionando a expressão e localização dessas proteínas com os dados descritos bem como evolução dos pacientes após 5 anos de acompanhamento. De acordo com os resultados sugere-se que a MNMIIB expressa no EA possa indicar o potencial de metástase regional do CEC e a MNMIIC presente na zona de invasão tumoral (ZI) seja um fator predictor de prognóstico ruim da doença. Sendo assim, é possível propor que a avaliação de imunorreatividade da MNMIIB no EA e MNMIIC na ZI seja utilizada na análise das peças operatórias, como complemento à análise morfológica de rotina. / Squamous cell carcinoma (SCC) of the head and neck is a malignant neoplasm of poor prognosis and low survival rate. Understand the biological processes involved in carcinogenesis can be extremely important for the development of new treatment technologies and improved prognosis in patients affected by the disease. The major cause of clinical failure in terms of therapy and prognosis in cancer patients is the development of tissue invasion and metastatic potential. Cell migration is essential for tumor progression and the cells have molecular motors especially formed from non-muscular myosin II family (NMMII). Encoded by different genes, there are three known isoforms in mammalian cells (NMMIIA, NMMIIB, NMMIIC). The NMMIIs are involved in cellular functions such as migration, adhesion, and cytokinesis. As the understanding of migration, cell adhesion and cytokinesis key factors in tumor progression, and that the tissue invasion and metastatic potential for development are essential in defining the prognosis of patients, the objective of this study was to describe the profile and exposure to risk factors such as alcohol and tobacco of patients diagnosed with head and neck SCC, histological grading, tumor clinical parameters (TNM), pattern of expression of isoforms NMMII (NMMIIA, NMMIIB, NMMIIC) in the center of the tumor (CT), tumor invasion zone area and not neoplastic adjacent to the tumor (AE), relating the expression and localization of these proteins with the data described and outcome of patients after 5 years of follow-up. According to the results it is suggested that the NMMIIB expressed in AE may indicate the potential regional metastasis of SCC and NMMIIC present in the tumor invasion zone (IZ) is a predictor factor of poor prognosis of the disease. Therefore, it is possible to propose that immunoreactivity assessment of NMMIIB in EA and NMMIIC in IZ could be used in the analysis of operative parts, as a complement to routine morphological analysis.

O carcinoma espinocelular (CEC) de cabeça e pescoço é uma neoplasia maligna de prognóstico desfavorável e baixa taxa de sobrevida. Entender os processos biológicos envolvidos na carcinogênese poderá ser de extrema importância para o desenvolvimento de novas tecnologias de tratamento e melhora do prognóstico em pacientes acometidos pela doença. A maior causa de insucessos clínicos em termos de terapia e prognóstico em pacientes com câncer é a invasão tecidual e o desenvolvimento de potencial metastático. A migração celular é indispensável para a progressão tumoral e as células apresentam motores moleculares desempenhados especialmente pela família da Miosina II não muscular (MNMII). Codificadas por diferentes genes, existem três isoformas conhecidas em células de mamíferos (MNMIIA, MNMIIB, MNMIIC). As MNMIIs estão envolvidas em funções celulares como migração, adesão e citocinese. Sendo o entendimento da migração, adesão celular e citocinese fatores chave na progressão tumoral, e que o a invasão tecidual e o desenvolvimento de potencial metastático são essenciais na definição do prognóstico dos pacientes, o objetivo deste estudo foi descrever o perfil e exposição à fatores de risco como álcool e fumo dos pacientes diagnosticados com CEC de cabeça e pescoço, graduação histológica, parâmetros clínicos tumorais (TNM), padrão de expressão das isoformas de MNMII (MNMIIA, MNMIIB, MNMIIC) no centro do tumor, zona de invasão e tecido epitelial não neoplásico adjacente ao tumor, relacionando a expressão e localização dessas proteínas com os dados descritos bem como evolução dos pacientes após 5 anos de acompanhamento. De acordo com os resultados sugere-se que a MNMIIB expressa no EA possa indicar o potencial de metástase regional do CEC e a MNMIIC presente na zona de invasão tumoral (ZI) seja um fator predictor de prognóstico ruim da doença. Sendo assim, é possível propor que a avaliação de imunorreatividade da MNMIIB no EA e MNMIIC na ZI seja utilizada na análise das peças operatórias, como complemento à análise morfológica de rotina. / Squamous cell carcinoma (SCC) of the head and neck is a malignant neoplasm of poor prognosis and low survival rate. Understand the biological processes involved in carcinogenesis can be extremely important for the development of new treatment technologies and improved prognosis in patients affected by the disease. The major cause of clinical failure in terms of therapy and prognosis in cancer patients is the development of tissue invasion and metastatic potential. Cell migration is essential for tumor progression and the cells have molecular motors especially formed from non-muscular myosin II family (NMMII). Encoded by different genes, there are three known isoforms in mammalian cells (NMMIIA, NMMIIB, NMMIIC). The NMMIIs are involved in cellular functions such as migration, adhesion, and cytokinesis. As the understanding of migration, cell adhesion and cytokinesis key factors in tumor progression, and that the tissue invasion and metastatic potential for development are essential in defining the prognosis of patients, the objective of this study was to describe the profile and exposure to risk factors such as alcohol and tobacco of patients diagnosed with head and neck SCC, histological grading, tumor clinical parameters (TNM), pattern of expression of isoforms NMMII (NMMIIA, NMMIIB, NMMIIC) in the center of the tumor (CT), tumor invasion zone area and not neoplastic adjacent to the tumor (AE), relating the expression and localization of these proteins with the data described and outcome of patients after 5 years of follow-up. According to the results it is suggested that the NMMIIB expressed in AE may indicate the potential regional metastasis of SCC and NMMIIC present in the tumor invasion zone (IZ) is a predictor factor of poor prognosis of the disease. Therefore, it is possible to propose that immunoreactivity assessment of NMMIIB in EA and NMMIIC in IZ could be used in the analysis of operative parts, as a complement to routine morphological analysis.

To understand the role of nonmuscle myosin II in cardiac and skeletal muscle, we used a number of polyclonal antibodies, three detecting nonmuscle myosin heavy chain II-B (NMHC II-B) and two detecting NMHC II-A, to examine the localization of these two proteins in fresh-frozen, acetone-fixed sections of normal human and mouse hearts and human skeletal muscles. Results were similar in both species and were confirmed by examination of fresh- frozen sections of human hearts subjected to no fixation or to treatment with either 4% p-formaldehyde or 50% glycerol. NMHC II-B was diffusely distributed in the cytoplasm of cardiac myocytes during development, but after birth it was localized to the Z-lines and intercalated discs. Dual labeling showed almost complete colocalization of NMHC II-B with α-actinin. Whereas endothelial cells, smooth muscle cells and fibroblasts showed strong immunoreactivity for NMHC II-A and NMHC II-B, cardiac myocytes only showed reactivity for the latter. The Z-lines of human skeletal muscle cells, in contrast to those of cardiac myocytes, gave positive reactions for both NMHC II-A and NMHC II-B. The presence of a motor protein in the Z-lines and intercalated discs raises the possibility that these structures may play a more dynamic role in the contraction/relaxation mechanism of cardiac and skeletal muscle than has been previously suspected.

No description available.

Le complexe actomyosine, formé de l’association de la myosine II avec les filaments d’actine, stabilise le cytosquelette d’actine et génère la contraction cellulaire nécessaire à plusieurs processus comme la motilité et l’apoptose dans les cellules non-musculaires. La myosine II est un hexamère formé d’une paire de chaînes lourdes (MHCs) et de deux paires de chaînes légères MLC20 et MLC17. La régulation de l’activité de la myosine II, c'est-à-dire son interaction avec les filaments d’actine, est directement liée à l’état de phosphorylation des MLC20, mais il reste beaucoup à découvrir sur l’implication des MHCs. Il existe trois isoformes de MHCs de myosine II, MHCIIA, MHCIIB et MHCIIC qui possèdent des fonctions à la fois communes et distinctes. Notre but est de mettre en évidence les différences de fonction entre les isoformes de myosine II, au niveau structurale, dans la stabilisation du cytosquelette d’actine, et au niveau de leur activité contractile, dans la génération des forces de tension. Nous nous sommes intéressés au rôle des isoformes des MHCs dans l’activité du complexe actomyosine qui est sollicité durant le processus de contraction cellulaire de l’apoptose. Dans quatre lignées cellulaires différentes, le traitement conjoint au TNFα et à la cycloheximide causait la contraction et le rétrécissement des cellules suivi de leur détachement du support de culture. Par Western blot, nous avons confirmé que la phosphorylation des MLC20 est augmentée suite au clivage de ROCK1 par la caspase-3, permettant ainsi l’interaction entre la myosine II et les filaments d’actine et par conséquent, la contraction des cellules apoptotiques. Cette contraction est bloquée par l’inhibition des caspases et de ROCK1. MHCIIA est dégradée suite à l’activation de la caspase-3 alors que MHCIIB n’est pas affectée. En utilisant une lignée cellulaire déficiente en MHCIIB, ou MHCIIB (-/-), nous avons observé que la contraction et le détachement cellulaires durant l’induction de l’apoptose se produisaient moins rapidement que dans la lignée de type sauvage (Wt) ce qui suggère que l’isoforme B est impliquée dans la contraction des cellules apoptotiques. Parallèlement, la kinase atypique PKCζ, qui phosphoryle MHCIIB et non MHCIIA, est activée durant l’apoptose. PKCζ joue un rôle important puisque son inhibition bloque la contraction des cellules apoptotiques. Par la suite, nous nous sommes intéressés à la modulation de la morphologie cellulaire par la myosine II. Les fibroblastes MHCIIB (-/-), présentent un large lamellipode dont la formation semble dû uniquement à l’absence de l’isoforme MHCIIB, alors que les fibroblastes Wt ont une morphologie cellulaire étoilée. La formation du lamellipode dans les fibroblastes MHCIIB (-/-) est caractérisée par l’association de la cortactine avec la membrane plasmique. L’observation en microscopie confocale nous indique que MHCIIA interagit avec la cortactine dans les fibroblastes Wt mais très peu dans les fibroblastes MHCIIB (-/-). Le bFGF active la voie des MAP kinases dans les fibroblastes Wt et MHCIIB (-/-) et induit des extensions cellulaires aberrantes dans les fibroblastes MHCIIB (-/-). Nos résultats montrent que l’implication de l’isoforme B de la myosine II dans la modulation de la morphologie cellulaire. L’ensemble de nos résultats participe à distinguer la fonction structurale et contractile de chacune des isoformes de myosine II dans la physiologie cellulaire. / We are interested in studying the modulation of the actomyosin complex which is involved in different cellular processes such as cell locomotion and apoptosis. The actomyosin complex is formed by the association of actin filaments and myosin II. The non-muscle myosin II is a hexamer formed by one pair of heavy chains (MHCs) and two pairs of light chain (MLC20 and MLC17). The actomyosin activity is dependent on MLC20 and MHCs phosphorylation. There are three isoforms of MHCs (MHCIIA, MHCIIB and MHCIIC) which have common but also distinctive roles in several cellular processes. Our aim is to clarify the structural and contractile functions of each isoforme of myosin II in different cellular processes, in particular, cell contraction and cell morphology. First, we studied the implication of myosin II isoforms in cell shrinkage and detachment during apoptosis which are both dependent on actomyosin contractility. We treated four different cell lines with TNFα in combination with cycloheximide (CHX) to trigger apoptosis. We confirmed that TNFα induced caspase-3 activation, ROCK1 cleavage and increased MLC20 phosphorylation. We showed that TNFα/CHX induced the caspase-dependent MHCIIA degradation, whereas MHCIIB levels and association with the actin cytoskeleton remained virtually unchanged. Cell shrinkage and detachment were blocked by caspase and ROCK1 inhibitors. Using the MHCIIB (-/-) cell line, we observed that the absence of MHCIIB did not affect cell death rate. However, MHCIIB (-/-) fibroblasts showed more resistance to TNFα-induced actin disassembly, cell shrinkage and detachment than wild type (Wt) fibroblasts, indicating the participation of MHCIIB in these events. PKCζ, which only phosphorylates MHCIIB, was cleaved during apoptosis, co-immunoprecipitated preferentially with MHCIIB and, interestedly, PKCζ inhibition blocked TNFα-induced shrinkage and detachment. Our results demonstrate that MHCIIB, together with MLC phosphorylation and actin, constitute the actomyosin cytoskeleton that mediates contractility during apoptosis. Second, we studied the involvement of myosin II isoforms in cell shape modulation. Fibroblasts MHCIIB (-/-) spontaneously formed lamellipodia whereas Wt fibroblasts presented a stellate shape. Cortactin was associated with the leading edge of lamellipodia in MHCIIB (-/-) fibroblasts, but it localised diffusely in the cytoplasm or at the end of fine cellular projections in Wt fibroblasts. The levels of cortactin and cortactin phosphorylated in Tyr421 associated with membrane in MHCIIB (-/-) fibroblasts were higher than in Wt fibroblasts. Confocal microscopy showed cortactin/MHCIIA colocalization in wild type but not in MHCIIB (-/-) fibroblasts. bFGF activates Erk1/2 in wild type and MHCIIB (-/-) fibroblasts and induces the formation of aberrant membrane projections in MHCIIB (-/-) fibroblasts. In conclusion, our results contribute to characterize the structural and contractile role of each myosin II isoforms in the physiology of the cell.

No description available.