Utilização de lectinas na caracterização bioquímica de antígenos de natureza glicídica presentes na membrana de cinco variantes de células de cancer de cólon humano

Abstract

In the present work carbohydrate of membrane from 05 cellular cellular variants of the human colon cancer (LS 180, EB3, 3LNLN, 5W and 8W) were analysed. In order to discriminate the types of glycan present on those cell surfaces, 15 lectins with known specificity and coupled to PITC were used. They were obtained from seeds plants namely Canavalia ensiformis (Con A), Canavalia brasiliensis (Con Br), Canavalia bonariensis (Con Bo) Canavalia grandiflora (Con Gr) and Canavalia maritima (Con M); Dioclea grandiflora (DGL), Dioclea guianensis (Dgui), Dioclea virgata (Dvir), Dioclea violacea (Dvio) and Dioclea rostrata (Dros); Cratylia floribunda (CFL); Parkia platycephala (PPL); Vatairea macrocarpa (VML); Lotus tetragonolobus (LTA) and Ulex europeus (UEA-I). The results of flow cytometry revealed that all lectins tested are able to recognise were the glycans structures on the cell surface studied. However, some of the lectins assayed were able to differentiate one or more variant cell (as in the case of Con Bo). Despite the high homology, lectins from Diocleinae sub-tribe exhibited different capacity to recognise the cells from different strands. From all lectins tested UEA-I and LTA (both fucose-specific) have showed higher binding capacity indicating the presence of high levels of fucosylated glycans. The fucosyltranferases analysis has revealed the presence of a great amount of enzymes that catalyse the formation of fucosylated type Lewis structures with higher levels of Lewis x and lewis a, and low levels of Lewis b. Lewis " type structures were not detected. Upon the bioadhesive capacity of the lectins using confocal microscopy it was possible to confirm the high levels of fucosylated structures (recognized by UEA-I and LTA). Interestingly, it was been found that both Con Bo and Dros lectins seem to potentialize theiruptake, since they appear almost completely in the cytoplasm after a hour at 37° C.