ABSTRACT
AIM: To study the effects of total phytohemagglutinin (PHA) and its isolectins on cell death and apoptosis in human HEp-2 carcinoma cells and to analyze the possible molecular mechanisms of lectin induced apoptosis. MATERIALS AND METHODS: The commercial preparation of the kidney beans (Phaseolus vulgaris) lectins and HEp-2 cells were used. Apoptosis index was determined using acridine orange and ethidium bromide staining. The expression levels of apoptosis mediator cleaved caspase-3 and proapoptotic Bax protein were studied by Western blot analysis. The gene expression levels were analyzed by qPCR. RESULTS: PHA and its isolectins induced apoptosis in HEp-2 cells accompanied by the increased expression of caspase-3 cleaved form, with PHA-E being the most effective. The treatment of HEp-2 cells with PHA or its isolectins resulted in a marked increase of Bax on both mRNA and protein levels. CONCLUSIONS: PHA and its isolectins were shown to induce the apoptosis in human HEp-2 carcinoma cells via increasing proapoptotic protein Bax and activating caspases-3.
Subject(s)
Antineoplastic Agents, Phytogenic/pharmacology , Apoptosis/drug effects , Phytohemagglutinins/pharmacology , Apoptosis Regulatory Proteins/genetics , Apoptosis Regulatory Proteins/metabolism , Cell Line, Tumor , Drug Screening Assays, Antitumor , HumansABSTRACT
Phytohemagglutinine (PHA) is widely investigated lectin with mitogenic properties. Recently it was shown that PHA is not only cell proliferation inducer, but also has a toxic or cytostatic effect. However concentration dependence and molecular mechanisms of this effect are not enough investigated. To study proapoptotic properties of total phytohemagglutinine and its isolectins in human cell culture of not tumor origin 4BL we observed a change in the frequency of apoptotic cells in the tested cell culture under the influence of the total phytohemagglutinine and erythroagglutinin by the method of specific color luminescent dye. The activation of caspases-3 and -8 and induction of protein Bax expression under the influence of lectins were detected by Western blot analysis. It was revealed that erythroagglutinin induced apoptosis with the highest efficiency compared with leukoagglutinin and total phytohemagglutinine. The induction of apoptosis in human cell culture of not tumor origin 4BL is probably caused by activating caspase-dependent and mitochondrial signalling.
Subject(s)
Apoptosis/drug effects , Phytohemagglutinins/pharmacology , Caspase 3/metabolism , Caspase 8/metabolism , Cell Culture Techniques , Cell Line , Electrophoresis, Polyacrylamide Gel , Humans , Plant Lectins/pharmacology , bcl-2-Associated X Protein/metabolismABSTRACT
Using the bacterium B. subtilis as a model and antibiotics as metabolic inhibitors which can suppress replication (mitomycin), transcription (rifampycin) or translation (streptomycin), it is shown that carbohydrate-binding proteins (lectins of plant origin) have different action on intracellular processes under study. The effect depends on lectin's structure and on the condition of bacterial reparation/recombination system. Lectins with chitin-binding domain (STA, WGA) is characterized by the most expressed effect on the repair-proficient strain when the inhibitor of template function of DNA (mitomycin C) was used. The absence of such effect on mutants recP and polC may prove that the corresponding bacterial proteins play the role of mediators in transmission of the signal influence of lectins. The representative of ribosome-inactivating lectins--SNA-I--could increase the streptomycin effect. It is proposed that intracellular effects of lectins have complex mechanisms which need participation of repair functions.
