DTCM-glutarimide Delays Growth and Radiosensitizes Glioblastoma.

BACKGROUND AND PURPOSE: Glioblastoma (GBM) is the most aggressive brain tumor. Even with the advent of temozolomide, patient survival remains poor, with expected median survival around 1 year from diagnosis. Consequently, the relentless search for new therapeutic strategies able to increase patient outcome persists. 3-[(dodecylthiocarbonyl) methyl] glutarimide (DTCM-g) is a new anti-inflammatory compound that already showed antitumor effects. MATERIALS AND METHODS: Clonogenic survival, proliferation, apoptosis, cell cycle progression and invasion capacity of pediatric and adult GBM cell lines (U87MG, U251MG, SF188 and KNS-42) were evaluated under treatment with DTCM-g. The combined treatment with radiation was also evaluated in vitro and in vivo through xerographic models. RESULTS: DTCM-g is able to impair proliferation, reduce clonogenic capacity and induce cell cycle arrest in GBM cell lines. No alteration in apoptosis rates was found after treatment. DTCM-g also reduces the invasion capacity of all GBM cell lines without alterations in MMP2 and uPa expression. Moreover, the drug radiosensitized GBM in vitro and in vivo. CONCLUSION: Although additional studies are still necessary to support our findings, our results suggest that DTCM-g may be a promising drug on the adjuvant treatment of GBM exhibiting antitumor effects, especially through radiosensitization.

Reversine triggers mitotic catastrophe and apoptosis in K562 cells.

Chronic myeloid leukemia (CML) is a clonal myeloproliferative neoplasm of the hematopoietic stem cell characterized by presence of the oncoprotein BCR-ABL1, which have constitutive tyrosine kinase activity. BCR-ABL1 activation induces aurora kinase A (AURKA) and aurora kinase B (AURKB) expression, which are serine-threonine kinases that play an important function in chromosome alignment, segregation and cytokinesis during mitosis. Acquisition of resistance to tyrosine kinase inhibitors has emerged as a problem for CML patients and the identification of novel targets with an important contribution for CML phenotype is of interest. In the present study, we explored the cellular effects of reversine, an AURKA and AURKB inhibitor, in the BCR-ABL1+ K562 cells. Our results indicate that reversine reduces AURKA and AURKB expression, leads to reduction of cell viability and increased apoptosis in a dose- and time-dependent manner, as well as, induces mitotic catastrophe in K562 cells. Our preclinical study establishes that reversine presents an effective antileukemia activity against K562 cells and provide new insights on anticancer opportunities for CML.

Isolation, functional, and partial biochemical characterization of galatrox, an acidic lectin from Bothrops atrox snake venom.

Snake venom lectins have been studied in regard to their chemical structure and biological functions. However, little is known about lectins isolated from Bothrops atrox snake venom. We report here the isolation and partial functional and biochemical characterization of an acidic glycan-binding protein called galatrox from this venom. This lectin was purified by affinity chromatography using a lactosyl-sepharose column, and its homogeneity and molecular mass were evaluated by high-performance liquid chromatography, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. The purified galatrox was homogeneous and characterized as an acidic protein (pI 5.2) with a monomeric and dimeric molecular mass of 16.2 and 32.5 kDa, respectively. Alignment of N-terminal and internal amino acid sequences of galatrox indicated that this protein exhibits high homology to other C-type snake venom lectins. Galatrox showed optimal hemagglutinating activity at a concentration of 100 µg/ml and this effect was drastically inhibited by lactose, ethylenediaminetetraacetic acid, and heating, which confirmed galatrox's lectin activity. While galatrox failed to induce the same level of paw edema or mast cell degranulation as B. atrox crude venom, galatrox did alter cellular viability, which suggested that galatrox might contribute to venom toxicity by directly inducing cell death.

Cell cycle arrest evidence, parasiticidal and bactericidal properties induced by L-amino acid oxidase from Bothrops atrox snake venom.

The present article describes an l-amino acid oxidase from Bothrops atrox snake venom as with antiprotozoal activities in Trypanosoma cruzi and in different species of Leishmania (Leishmania braziliensis, Leishmania donovani and Leishmania major). Leishmanicidal effects were inhibited by catalase, suggesting that they are mediated by H(2)O(2) production. Leishmania spp. cause a spectrum of diseases, ranging from self-healing ulcers to disseminated and often fatal infections, depending on the species involved and the host's immune response. BatroxLAAO also displays bactericidal activity against both Gram-positive and Gram-negative bacteria. The apoptosis induced by BatroxLAAO on HL-60 cell lines and PBMC cells was determined by morphological cell evaluation using a mix of fluorescent dyes. As revealed by flow cytometry analysis, suppression of cell proliferation with BatroxLAAO was accompanied by the significant accumulation of cells in the G0/G1 phase boundary in HL-60 cells. BatroxLAAO at 25 µg/mL and 50 µg/mL blocked G0-G1 transition, resulting in G0/G1 phase cell cycle arrest, thereby delaying the progression of cells through S and G2/M phase in HL-60 cells. This was shown by an accentuated decrease in the proportion of cells in S phase, and the almost absence of G2/M phase cell population. BatroxLAAO is an interesting enzyme that provides a better understanding of the ophidian envenomation mechanism, and has biotechnological potential as a model for therapeutic agents.

Evidence of caspase-mediated apoptosis induced by l-amino acid oxidase isolated from Bothrops atrox snake venom.

The aim of this work was to investigate the involvement of caspases in apoptosis induced by l-amino acid oxidase isolated from Bothrops atrox snake venom. The isolation of LAAO involved three chromatographic steps: molecular exclusion on a G-75 column; ion exchange column by HPLC and affinity chromatography on a Lentil Lectin column. SDS-PAGE was used to confirm the expected high purity level of BatroxLAAO. It is a glycoprotein with 12% sugar and an acidic character, as confirmed by its amino acid composition, rich in "Asp and Glu" residues. It displays high specificity toward hydrophobic l-amino acids. The N-terminal amino acid sequence and internal peptide sequences showed close structural homology to other snake venom LAAOs. This enzyme induces in vitro platelet aggregation, which may be due to H2O2 production by LAAOs, since the addition of catalase completely inhibited the aggregation effect. It also showed cytotoxicity towards several cancer cell lines: HL60, Jurkat, B16F10 and PC12. The cytotoxicity activity was abolished by catalase. A fluorescence microscopy evaluation revealed a significant increase in the apoptotic index of these cells after BatroxLAAO treatment. This observation was confirmed by phosphatidyl serine exposure and activation of caspases. BatroxLAAO is a protein with various biological functions that can be involved in envenomation. Further investigations of its function will contribute to toxicology advances.

Molecular characterization of swine hepatitis E virus from Southeastern Brazil

Despite serological evidences of presence of hepatitis E virus (HEV) in humans or other animals, until this study the virus had not been detected and molecular characterization of the isolate that circulates in Brazil had not been described. Thus, we collected stool samples of young pigs and tested for presence of HEV RNA by RT-PCR, using primers for partial amplification of ORF2 sequence. Phylogenetic analysis with sequence obtained from the amplified products revealed that the HEV isolate identified here was most closely related to HEV isolates of genotype 3, which is commonly detected in HEV infected pigs. Nucleotide sequence analyses carried out with the entire amplified fragment, ORF2/ORF3 overlapping and ORF2 non-overlapping sequences showed highest identities with the US isolate of genotype 3. Similarly, amino acid sequence analyses done with the entire amplified fragment, ORF2 non-overlapping, ORF2 and ORF3 overlapping sequences also showed highest identities with the genotype 3 isolate. Presence, in Brazil, of HEV of genotype 4, which also infects pigs, as well as HEV strains that infect humans still remain to be detected and characterized.

Apesar de evidências sorológicas da presença do vírus da hepatite E (VHE) em humanos ou outros animais, até o presente estudo o vírus não havia sido detectado e a caracterização molecular da cepa que circula no Brasil não havia sido descrita. Assim, amostras de fezes de porcos jovens foram colhidas e analizadas quanto a presença do ARN do VHE por RT-PCR, utilizando-se oligonucleotídeos para amplificação da seqüência parcial do ORF2 viral. Análise filogenética realizada com a seqüência obtida dos produtos amplificados revelou que a cepa encontrada apresentou relação próxima com cepas do genótipo 3 que são detectadas com freqüência em porcos. Análises das seqüências nucleotídicas realizadas com todo o segmento amplificado, com somente o segmento sobreposto do ORF2/ORF3 e aquele sem sobreposição do ORF2, em comparação com isolados de genótipos conhecidos, mostraram maior identidade com o isolado encontrado nos Estados Unidos (US) do genótipo 3. De maneira semelhante, análises da seqüência de aminoácidos realizadas com os mesmos segmentos também mostraram maior identidade com o isolado de genótipo 3. Presença ou não do vírus de genótipo 4, que também infecta porcos, ainda necessita ser verificada. Da mesma forma, cepas do VHE que infectam humanos ainda necessitam ser detectadas e caracterizadas.