Hyaluronan density influences adhesion, morphology and migration of cancer cells

Hyaluronan (HA) is a linear non-sulfated glycosaminoglycan present in the extracellular matrix and known to modulate cell-cell and cell-ECM interactions. In cancer, the synthesis, degradation and signaling of HA is altered. For instance, its main receptor, CD44, is overexpressed in several types of cancer and has been correlated with disease progression through cancer cell proliferation, migration and chemoresistance. Herein, we investigated the behavior of breast cancer cells with different CD44 expression and invasion profile on HA density gradients. These gradients were achieved by deposition of colloidal gold (Au) on amino-functionalized surfaces at different ionic strengths and following binding of end-on thiol modified HA on the Au. At low HA density, small number of adherent round cells were found for all studied cell lines. Cells adherent to the areas with high HA density presented a spindle-like morphology. The differences were more pronounced for cells overexpressing CD44. These cells also form long filopodia when adhered on areas with middle and high HA density. Of note, colocalization of CD44 and actin was observed at the filopodias edges. Cell motility was also affected by the gradient – at low densities cells presented higher motility, which decreased with the increase of HA density. Besides this common trend, we observed differences among the studied cells. CD44 cells had shorter persistent length displacement than CD44 and CD44cells. Upon CD44 blockage, all types of cells (CD44++, CD44+, and CD44-) behave similarly . These results suggest that cells recognize HA gradients through CD44 receptors and that the HA density can be used to sort cells with different expression of this receptor.info:eu-repo/semantics/publishedVersio

Análise da expressão gênica, sob condições de déficit hídrico, em limoeiro 'Cravo' (Citrus limonia OSBECK).

A citricultura brasileira é um dos setores mais competitivos do agronegócio global, e o Brasil ocupa a posição de maior produtor mundial de citros e exportador de suco concentrado congelado. O Nordeste brasileiro, por sua vez, detém, após o Estado de São Paulo, a citricultura de maior expressão, graças à liderança nesse setor dos Estados da Bahia e Sergipe, que praticamente se igualam na produção de citros. Um dos problemas que podem afetar drasticamente a produção nacional é a carência de genótipos capazes de tolerar a seca. O ácido abscísico (ABA) desempenha um papel crucial na regulação dos níveis de água através das células guardas, e também na indução de genes envolvidos na tolerância à seca. Dessa forma, o objetivo deste trabalho foi determinar, a partir de análise fisiológica, os níveis de expressão dos genes ost1 (Open Stomata1) e sad1 (ABA supersensitivo à seca) em plantas de limoeiro ‘Cravo‘ submetidas ao déficit hídrico, por meio da técnica de RT-qPCR. O papel do gene ost1 consiste em atuar como um regular positivo na indução do ABA no fechamento estomático. Já o sad1 é um importante regulador negativo que modula o metabolismo de RNA como splicing, exportação e degradação, controlando a sensibilidade do ABA à seca nas plantas. Neste estudo foram utilizadas dez plantas nucelares, das quais cinco controles e cinco submetidas ao estresse hídrico. O experimento foi conduzido em casa de vegetação com temperatura e umidade monitoradas por 15 dias com as plantas mantidas em vasos de 5 litros. Durante a análise fisiológica foi medido o conteúdo de água do solo em diferentes horários a cada dia, obtido pela TDR (reflectometria no domínio do tempo), e amostras foliares foram coletadas em 3 estágios do déficit para posteriores análises de expressão gênica. A partir da extração de RNA, seguido pela síntese de cDNA, foi detectada a presença dos genes ost1 e sad1 em folhas de limoeiro ‘Cravo’ pelo RT-qPCR. Comparando-se as plantas estressadas e as plantas controle, verificou-se o nível de expressão dos genes com a indução do ost1 de 2,37 vezes nas plantas estressadas e no sad1 uma repressão de 6,25 vezes. Dessa maneira, fica evidente a ativação do gene ost1 e este por sua vez, tende a desencadear o mecanismo de fechamento estomático. Já o observado com o sad1 é semelhante ao relatado em outros trabalhos onde o decréscimo de sua expressão ocorra pelo aumento da concentração de ABA. Confirmase então, o envolvimento destes genes nas respostas do limoeiro ‘Cravo’ à seca e que novos estudos estão sendo realizados a fim de elucidar o envolvimento de outros genes presentes na rota do ácido abscísico em relação ao estresse hídrico.PDF 104

Short carbohydrate amphiphiles as smart therapeutics targeting cancer

Biocatalytic self-assembly (BSA) emerged as selective and effective approach for cancer therapy. BSA makes use of enzyme-sensitive moiety that is incorporated in an amphiphilic molecule (usually peptide amphiphile, PA). This unit is transfomred/removed upon enzymatic action causing rebalance of the moleculeâ s amphiphilicity and self-assembling ability. Among different enzymes, phosphatases (e.g. alkaline phosphatase, ALP) are the best studied ones for BSA targeting cancer. Recently, we describe a simple carbohydrate amphiphile (CA) as an alternative of PA and demonstrated its potential for treatment of osteosarcoma using BSA. Herein, we discuss another advantage of CAs in cancer therapy: they can act as antagonists of the glucose transporters (GLUTs) due to their structural similarity with glucose. Cancer cells have an accelerated metabolism, which requires high consumption of glucose. As a result, they overexpressed GLUTs, particularly GLUT1 and GLUT3. We studied several cancer cell lines overexpressing GLUTs and demonstrate that indeed the presence of CAs alter the glucose transport: a competitive assay showed that CAs reduced significantly the uptake of glucose, suggesting a possible blocking of GLUTs and glycolysis. Cancer cells cultured in the presence of CAs also showed a decrease in cell proliferation, metabolic activity and activation of an apoptotic pathway, that ultimately led to cell death. We conclude that the selective apoptosis of cancer cells is based on two synergistic mechanisms: formation of pericellular net that traps selectively the phosphatase overexpressing cells and blockage of glucose transport in these cells.info:eu-repo/semantics/publishedVersio

Numerical Study and Geometric Investigation of the Influence of Rectangular Baffles over the Mixture of Turbulent Flows into Stirred Tanks

The present work aims to define strategies for numerical simulation of the mixture of turbulent flows in a stirred tank with a low computational effort, and to investigate the influence of the geometry of four rectangular baffles on the problem of performance. Two computational models based on momentum source and sliding mesh are validated by comparison with experimental results from the literature. For both models, the time‐averaged conservation equations of mass, momentum and transport of the mixture are solved using the finite volume method (FVM) (FLUENT® v.14.5). The standard k–ε model is used for closure of turbulence. Concerning the geometrical investigation, constructal design is employed to define the search space, degrees of freedom and performance indicators of the problem. More precisely, seven configurations with different width/length (L/B) ratios for the rectangular baffles are studied and compared with an unbaffled case. The momentum source model leads to valid results and significantly reduces the computational effort in comparison with the sliding mesh model. Concerning the design, the results indicate that the case without baffles creates the highest magnitude of turbulence kinetic energy, but poorly distributes it along the domain. The best configuration, (L/B)o = 1.0, leads to a mixture performance nearly two times superior than the case without baffles