RESUMO
Colon cancer is one of the most common cancer around the world. Exopolysaccharides (EPSs) produced by lactobacilli as potential prebiotics have been found to have an anti-tumor effect. In this study, lyophilized EPSs of four Lactobacillus spp. for their impact on apoptosis in colon cancer cells (HT-29) was evaluated using flow cytometry. The relationship between capability of a lactobacilli-EPS to induce apoptosis and their monosaccharide composition, molecular weight (MW), and linkage type was investigated by HPLC, SEC, and NMR, respectively. Changes in apoptotic-markers were examined by qPCR and Western Blotting. EPSs were capable of inhibiting proliferation in a time-dependent manner and induced apoptosis via increasing the expression of Bax, Caspase 3 and 9 while decreasing Bcl-2 and Survivin. All EPSs contained mannose, glucose, and N-acetylglucosamine with different relative proportions. Some contained arabinose or fructose. MW ranged from 102-104Da with two or three fractions. EPS of L. delbrueckii ssp. bulgaricus B3 having the highest amount of mannose and the lowest amount of glucose, showed the highest apoptosis induction. In conclusion, lactobacilli-EPSs inhibit cell proliferation in HT-29 via apoptosis. Results suggest that a relationship exists between the ability of EPS to induce apoptosis and its mannose and glucose composition.
Assuntos
Apoptose/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Neoplasias do Colo/tratamento farmacológico , Polissacarídeos Bacterianos/farmacologia , Acetilglucosamina/química , Acetilglucosamina/farmacologia , Cromatografia Líquida de Alta Pressão , Neoplasias do Colo/genética , Neoplasias do Colo/patologia , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Glucose/química , Glucose/farmacologia , Células HT29 , Humanos , Lactobacillus/química , Espectroscopia de Ressonância Magnética , Manose/química , Manose/farmacologia , Monossacarídeos/química , Monossacarídeos/farmacologia , Polissacarídeos Bacterianos/química , Polissacarídeos Bacterianos/ultraestrutura , Proteínas Proto-Oncogênicas c-bcl-2/genética , Survivina/genéticaRESUMO
One iron(III) and two manganese(III) complexes based on thiosemicarbazone were synthesized and characterized using analytical and spectroscopic data. The crystallographic analysis showed the square pyramid structures of the complexes. Electronic spectra analysis was performed to determine the nature of the interaction between the complexes and calf thymus DNA (CT-DNA). DNA cleavage activities of the complexes were examined by gel electrophoresis (pBR322 DNA). The cytotoxicity of the complexes was determined against human cervical carcinoma (HeLa) and human colorectal adenocarcinoma (HT-29) cell lines by MTT assay. The results indicated that complex Fe1 is bound to CT-DNA via the intercalation mode, while complexes Mn1 and Mn2 are bound to CT-DNA via groove binding and/or electrostatic interactions rather than the intercalation mode. In addition, they showed good binding activity, which followed the order of Fe1 > Mn2 > Mn1. Complexes were found to promote the cleavage of DNA from supercoiled form (SC, Form I) to nicked circular form (NC, Form II) without concurrent formation of Form III, revealing the single-strand DNA cleavage. No significant cleavage was found in the presence of Mn1 and Mn2; however, it was observed at 2000 and 3000 µM concentrations of Fe1. The ability of Fe1 to cleave DNA was greater than that of other complexes and these results are in conformity with their DNA-binding affinities. Cytotoxicity determination tests revealed that the complex Fe1 on HeLa and HT-29 cells exhibited a higher anti-proliferative effect than Mn1 and Mn2 (Fe1 > Mn2 > Mn1). These studies suggested that the complex Fe1 could be a good candidate as a chemotherapeutic drug targeting DNA.
