ABSTRACT
A glioblastoma (GBM) is a highly malignant primary brain tumor with a poor prognosis because of its invasiveness and high resistance to current therapies. In GBMs, abnormal glycosylation patterns are associated with malignancy, which allows for the use of lectins as tools for recognition and therapy. More specifically, lectins can interact with glycan structures found on the malignant cell surface. In this context, the present work aimed to investigate the antiglioma potential of ConGF, a lectin purified from Canavalia grandiflora seeds, against C6 cells. The treatment of C6 cells with ConGF impaired the mitochondrial transmembrane potential, reduced cell viability, and induced morphological changes. ConGF also induced massive autophagy, as evaluated by acridine orange (AO) staining and LC3AB-II expression, but without prominent propidium iodide (PI) labeling. The mechanism of action appears to involve the carbohydrate-binding capacity of ConGF, and in silico studies suggested that the lectin can interact with the glycan structures of matrix metalloproteinase 1 (MMP1), a prominent protein found in malignant cells, likely explaining the observed effects.
Subject(s)
Canavalia , Fabaceae , Canavalia/chemistry , Fabaceae/chemistry , Lectins/chemistry , Matrix Metalloproteinase 1 , Propidium , Acridine Orange , Plant Lectins/chemistry , Seeds/chemistry , Carbohydrates/analysisSubject(s)
Dioclea/chemistry , Mannose-Binding Lectins/chemistry , Plant Lectins/chemistry , Seeds/chemistry , Animals , Apoptosis/drug effects , Binding Sites , Cell Line, Tumor , Cell Movement/drug effects , Cell Survival/drug effects , Crystallization , Glioma , Mannose-Binding Lectins/isolation & purification , Mannose-Binding Lectins/pharmacology , Molecular Docking Simulation , Plant Lectins/isolation & purification , Plant Lectins/pharmacology , Protein Binding , Protein Conformation , RatsABSTRACT
CaBo is a mannose/glucose-specific lectin purified from seeds of Canavalia bonariensis. In the present work, we report the CaBo crystal structure determined to atomic resolution in the presence of X-man, a specific ligand. Similar to the structural characteristics of other legume lectins, CaBo presented the jellyroll motif, a metal binding site occupied by calcium and manganese ions close to the carbohydrate-recognition domain (CRD). In vitro test of CaBo cytotoxicity against glioma cells demonstrated its ability to decrease the cellular viability and migration by induction of autophagy and cell death. Molecular docking simulations corroborate previous data indicating that the lectin's biological activities occur mostly through interactions with glycoproteins since the lectin interacted favorably with several N-glycans, especially those of the high-mannose type. Together, these results suggest that CaBo interacts with glycosylated cell targets and elicits a remarkable antiglioma activity.
Subject(s)
Antineoplastic Agents/chemistry , Autophagy/drug effects , Canavalia/chemistry , Methylmannosides/chemistry , Neuroglia/drug effects , Plant Lectins/chemistry , Amino Acid Motifs , Animals , Antineoplastic Agents/isolation & purification , Antineoplastic Agents/pharmacology , Binding Sites , Calcium/chemistry , Calcium/metabolism , Carbohydrate Sequence , Cations, Divalent , Cell Line, Tumor , Cell Movement/drug effects , Cell Survival/drug effects , Crystallography, X-Ray , Manganese/chemistry , Manganese/metabolism , Methylmannosides/metabolism , Molecular Docking Simulation , Neuroglia/pathology , Plant Lectins/isolation & purification , Plant Lectins/pharmacology , Protein Binding , Protein Interaction Domains and Motifs , Protein Multimerization , Protein Structure, Secondary , Rats , Substrate SpecificityABSTRACT
Lectins are multidomain proteins that specifically recognize various carbohydrates. The structural characterization of these molecules is crucial in understanding their function and activity in systems and organisms. Most cancer cells exhibit changes in glycosylation patterns, and lectins may be able to recognize these changes. In this work, Dioclea lasiocarpa seed lectin (DLL) was structurally characterized. The lectin presented a high degree of similarity with other lectins isolated from legumes, presenting a jelly roll motif and a metal-binding site stabilizing the carbohydrate-recognition domain. DLL demonstrated differential interactions with carbohydrates, depending on type of glycosidic linkage present in ligands. As observed by the reduction of cell viability in C6 cells, DLL showed strong antiglioma activity by mechanisms involving activation of caspase 3.
Subject(s)
Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Dioclea/chemistry , Glioma/pathology , Plant Lectins/chemistry , Plant Lectins/pharmacology , Animals , Antineoplastic Agents/metabolism , Carbohydrate Metabolism , Cell Line, Tumor , Cell Survival/drug effects , Molecular Docking Simulation , Plant Lectins/metabolism , Protein Conformation , Rats , Seeds/chemistryABSTRACT
A lectin from Canavalia virosa, Diocleinae subtribe, was purified by affinity chromatography with Sephadex G-50 matrix and named ConV. The primary structure of ConV was obtained by mass spectrometry and crystals were obtained by the vapor diffusion method at 293K and belonged to orthorhombic space group P21221 with two molecules in its asymmetric unit. The structure obtained presented Rfactor and Rfree of 18.91% and 24.92% respectively, with no residues in nonallowed regions of Ramachandran plot. The crystal structure was solved at 2.53Å and was demonstrated to be very similar to other lectins from the same subtribe. In inflammatory tests, ConV elicited paw edema, but incubation of lectin with glucose beforehand was able to reduce the edematogenic effect, indicating the involvement of the carbohydrate recognition domain in this process. The lectin also showed toxicity to rat C6 glioma cells, disrupting the mitochondrial membrane potential (ΔYm) and decreasing cell viability, indicating an anticancer potential for ConV. In silico studies confirmed that ConV interacts strongly with carbohydrates that comprise the N-glycans of glycoproteins. This finding corroborates the hypothesis which holds that the lectin domain interacts with glycans in molecular targets and that this contributes to the effects observed in biological activities.
