Induction of apoptosis by Polygonatum odoratum lectin and its molecular mechanisms in murine fibrosarcoma L929 cells.

BACKGROUND: The Galanthus nivalis agglutinin (GNA)-related lectins have been reported to bear antiproliferative and apoptosis-inducing activities in cancer cells; however, the precise mechanisms by which GNA-related lectins induce cell death are still only rudimentarily understood. METHODS: In the present study, Polygonatum odoratum lectin (designated POL), a mannose-binding specific GNA-related lectin, possessed a remarkable antiproliferative activity toward murine fibrosarcoma L929 cells. And, this lectin induced L929 cell apoptosis in a caspase-dependent manner. In addition, POL treatment increased the levels of FasL and Fas-Associated protein with Death Domain (FADD) proteins and resulted in caspase-8 activation. Also, POL treatment caused mitochondrial transmembrane potential collapse and cytochrome c release, leading to activations of caspase-9 and caspase-3. Moreover, POL treatment enhanced tumor necrosis factor alpha (TNFalpha)-induced L929 cell apoptosis. RESULTS: Our data demonstrate for the first time that this lectin induces apoptosis through both death-receptor and mitochondrial pathways, as well as amplifies TNFalpha-induced L929 cell apoptosis. GENERAL SIGNIFICANCE: These inspiring findings would provide new molecular basis for further understanding cell death mechanisms of the Galanthus nivalis agglutinin (GNA)-related lectins in future cancer investigations.

A novel sialic acid-specific lectin from Phaseolus coccineus seeds with potent antineoplastic and antifungal activities.

A novel lectin (PCL) with specificity towards sialic acid was purified from Phaseolus coccineus L. (P. multiflorus willd) seeds using ion exchange chromatography on CM and DEAE-Sepharose, and gel filtration on Sephacryl S-200 column. PCL was a homodimer consisting of 29,831.265 Da subunits as determined by gel filtration and MS. Also, PCL was a non-metalloprotein and its N-terminal 23-amino acid sequence, ATETSFSFQRLNLANLVLNKESS, was determined. Subsequently, MTT method, cell morphological analysis and LDH activity-based cytotoxicity assays demonstrated that PCL was highly cytotoxic to L929 cells and induced apoptosis in a dose-dependent manner. Using caspase inhibitors, a typical caspase-dependent pathway was confirmed. PCL also showed remarkable antifungal activity towards some plant pathogenic fungi. Furthermore, when sialic acid-specific activity was fully inhibited, cytotoxicity and antifungal activity were abruptly decreased, respectively, suggesting a significant correlation between sialic acid-specific site and its bi-functional bioactivities.

Nebrodeolysin, a novel hemolytic protein from mushroom Pleurotus nebrodensis with apoptosis-inducing and anti-HIV-1 effects.

A novel hemolysin was isolated from the edible mushroom Pleurotus nebrodensis by ion exchange and gel filtration chromatography on DEAE-Sepharose and Sephacryl S-100. The hemolysin from Pleurotus nebrodensis hemolysin (nebrodeolysin) is a monomeric protein with a molecular weight of approximately 27 kDa as determined by gel filtration and SDS-PAGE. Nebrodeolysin exhibited remarkable hemolytic activity towards rabbit erythrocytes and caused efflux of potassium ions from erythrocytes. Subsequently, this hemolysin showed strong cytotoxicity against Lu-04, Bre-04, HepG2, L929, and HeLa cells. It was also found that this hemolysin induced apoptosis in L929 and HeLa cells as evidenced by microscopic observations and DNA ladder, respectively. Moreover, this hemolysin was shown to possess anti-HIV-1 activity in CEM cell culture.

A mannose-binding lectin from Sophora flavescens induces apoptosis in HeLa cells.

The objective of this study was to investigate the anti-tumor activity of a lectin from Sophora flavescens and explore its potential apoptotic induction mechanism. Here, an elegant series of biochemical and cell biology methods were carried out in a sequential procedure (e.g., MTT, cell morphologic changes and LDH assays, DNA ladder as well as flow cytometric assay). As a result, we found that this lectin shows a strong cytotoxicity against HeLa cells and induces apoptosis in a time- and dose-dependent manner. Subsequently, according to caspase inhibition and Western blot analysis, we further demonstrated that it is a typical caspase-dependent apoptotic mechanism. Furthermore, we also exerted some bioinformatics methods to identify the mannose-binding specificity of this lectin. In conclusion, all experimental results demonstrated that this lectin seems to be a potent anti-tumor agent for its cytotoxicity and apoptosis effects on HeLa cells. Also, bioinformatics analyses showed that this lectin is speculated to bind a certain mannose-containing receptor on cancer cell surface thereby initiating downstream caspase cascade.