Isolation and Characterization of a Lactose-Binding Lectin from Ocimum sanctum.

A novel lectin has been isolated from Ocimum sanctum and purified to homogeneity by gel filtration chromatography, which eluted as a single symmetrical peak from a Biogel P-100 column with a molecular mass of 66 kDa. The lectin had a special agglutinating activity with human erythrocytes at a minimum concentration of 0.7 ug/ml. The lectin was stable in the pH range 5-12 and temperature 80 °C for 30 min. Ocimum sanctum had shown highest agglutinating activity at pH7 and 250C temperature after one hour incubation. Of the various sugars tested, even at 1000 mM sugar concentration, no inhibition was observed. The isolated lectin was found to be lactose-biding lectin sugar moieties and contain 2.6 mg/ml total sugar and 9.3 mg/ml of total protein.

Mecanismos celulares e moleculares envolvidos com alterações na expressão de glicanos durante a progressão do câncer colorretal / Cellular and molecular mechanisms involved with altered glycans expression colorectal cancer progression

O câncer colorretal representa uma das maiores causas de morbidade e mortalidade relacionadas ao câncer. No Brasil, é o terceiro tipo de câncer mais frequente em homens e mulheres. Muitos estudos estão sendo desenvolvidos no sentido de esclarecer os diversos aspectos moleculares que regulam as alterações fenotípicas exibidas pelas células que constituem o câncer colorretal, no entanto, comparativamente, ainda são poucos os que são dedicados a investigar o papel de modificações co- e pós-traducionais neste processo. Entre os vários tipos destas modificações que ocorrem em proteínas, a glicosilação é a mais comum. Cogita-se que aproximadamente cinquenta por cento de todas as proteínas são glicosiladas. Durante a transformação maligna, mudanças no perfil de expressão de glicanos (carboidratos covalentemente ligados a proteínas ou lipídios) estão envolvidas em uma variedade de mecanismos celulares, tais como: perda da adesão célula-célula e célula matriz, migração, invasão e evasão da apoptose. Neste estudo, foi investigada a atividade antitumoral de inibidores da biossíntese de N-glicanos, swainsonina e tunicamicina, em células derivadas de câncer colorretal (Caco-2, HCT-116 e HT-29). Os resultados obtidos mostram que o tratamento das células HCT-116 com tunicamicina inibe mecanismos celulares relacionados ao fenótipo maligno, como formação de colônia dependente e independente de ancoragem, migração e invasão. Estes resultados sugerem que modulação da biossíntese de N-glicanos parece ser uma potencial ferramenta terapêutica para o tratamento do câncer colorretal. Em outra etapa do trabalho, foram avaliados também o impacto da estimulação com insulina e IGF-1 na expressão N-glicanos bissectados em células tumorais MDA-MB-435. Os resultados obtidos confirmaram também a existência de uma relação entre a estimulação dos receptores de insulina e IGF-1 e a regulação da expressão de N-glicanos bissectados em células tumorais MDA-MB-435, fornecendo assim informações ...

Colorectal cancer is a major cause of cancer-related morbidity and mortality. In Brazil, it is the third most common cancer. Many studies have been developed to clarify several molecular features which regulate phenotypic changes exhibited by cells that constitute colorectal cancer, however, comparatively, there are few studies dedicated to investigate co- and post-translational modifications of proteins in this process. Glycosylation is the most common post-translational modification of proteins. Approximately fifty percent of all proteins are glycosylated. During malignant transformation, changes in the expression profile of glycans (carbohydrates covalently bound to proteins or lipids) may be involved in a variety of events, including the loss of cell–cell and cell–matrix adhesion, migration, invasion, and evasion of apoptosis. In this study, we investigated the in vitro anticancer activity of the N-glycan biosynthesis inhibitors, swainsonine and tunicamycin, in cells derived from colorectal cancer (Caco-2, HCT-116 e HT-29). Our results show that treatment with tunicamycin inhibits cellular mechanisms related to the malignant phenotype, such as anchorage-dependent and anchorage-independent colony formation, migration and invasion, in HCT-116 colon cancer cells. Given these results, we suggest that the modulation of N-glycan biosynthesis appears to be a potential therapeutic tool for CRC treatment. Moreover, we confirmthe existence of an interplay between stimulation with insulin and IGF-1 and bisecting GlcNAc N-glycans expression in MDA-MB435 cancer cells, providing new insights into the role that Insulin/IGF-I signaling play during carcinoma progression

Carbohydrate Vaccines- A burgeoning field of Glycomics.

Glycomics is the study that deals with the structures and functions of carbohydrates. The discovery Of novel and increasing number of numerous biological roles of carbohydrates , glycomics has explored the field of carbohydrate vaccines. Glycoconjugate vaccines in which the cell surface carbohydrate from a microorganism is covalently attached to a carrier protein are proving to be highly effective in generating protective immune responses to prevent a wide range of diseases. The carbohydrate based agents – glycoproteins and polysaccharides can be difficult to isolate from natural sources and the natural isolates can have heterogeneity and contamination. So, the alternative would be to identify antigenic carbohydrates and then synthesize them in the laboratory. Novel chemical and enzymatic oligosaccharide techniques are making it possible to envision a new generation of carbohydrate based vaccines. Carbohydrate vaccines have leading roles in cancer, haemophilus influenza B, malaria, candidiasis, AIDS etc. The present article focuses on the potential of carbohydrate vaccines, thus paving the way for development in the field of glycomics.