PGA1-induced apoptosis involves specific activation of H-Ras and N-Ras in cellular endomembranes.

The cyclopentenone prostaglandin A1 (PGA1) is an inducer of cell death in cancer cells. However, the mechanism that initiates this cytotoxic response remains elusive. Here we report that PGA1 triggers apoptosis by a process that entails the specific activation of H- and N-Ras isoforms, leading to caspase activation. Cells without H- and N-Ras did not undergo apoptosis upon PGA1 treatment; in these cells, the cellular demise was rescued by overexpression of either H-Ras or N-Ras. Consistently, the mutant H-Ras-C118S, defective for binding PGA1, did not produce cell death. Molecular analysis revealed a key role for the RAF-MEK-ERK signaling pathway in the apoptotic process through the induction of calpain activity and caspase-12 cleavage. We propose that PGA1 evokes a specific physiological cell death program, through H- and N-Ras, but not K-Ras, activation at endomembranes. Our results highlight a novel mechanism that may be of potential interest for tumor treatment.

Imidazole-containing phthalazine derivatives inhibit Fe-SOD performance in Leishmania species and are active in vitro against visceral and mucosal leishmaniasis.

The in vitro leishmanicidal activity of a series of imidazole-containing phthalazine derivatives 1-4 was tested on Leishmania infantum, Leishmania braziliensis and Leishmania donovani parasites, and their cytotoxicity on J774·2 macrophage cells was also measured. All compounds tested showed selectivity indexes higher than that of the reference drug glucantime for the three Leishmania species, and the less bulky monoalkylamino substituted derivatives 2 and 4 were clearly more effective than their bisalkylamino substituted counterparts 1 and 3. Both infection rate measures and ultrastructural alterations studies confirmed that 2 and 4 were highly leishmanicidal and induced extensive parasite cell damage. Modifications to the excretion products of parasites treated with 2 and 4 were also consistent with substantial cytoplasmic alterations. On the other hand, the most active compounds 2 and 4 were potent inhibitors of iron superoxide dismutase enzyme (Fe-SOD) in the three species considered, whereas their impact on human CuZn-SOD was low. Molecular modelling suggests that 2 and 4 could deactivate Fe-SOD due to a sterically favoured enhanced ability to interact with the H-bonding net that supports the antioxidant features of the enzyme.

In vitro leishmanicidal activity of pyrazole-containing polyamine macrocycles which inhibit the Fe-SOD enzyme of Leishmania infantum and Leishmania braziliensis species.

The in vitro leishmanicidal activity and cytotoxicity of pyrazole-containing macrocyclic polyamines 1-4 was assayed on Leishmania infantum and Leishmania braziliensis species. Compounds 1-4 were more active and less toxic than glucantime and both infection rates and ultrastructural alterations confirmed that 1 and 2 were highly leishmanicidal and induced extensive parasite cell damage. Modifications in the excretion products of parasites treated with 1-3 were also consistent with substantial cytoplasm alterations. Compound 2 was highlighted as a potent inhibitor of Fe-SOD in both species, whereas its effect on human CuZn-SOD was poor. Molecular modelling suggested that 2 could deactivate Fe-SOD due to a sterically favoured enhanced ability to interact with the H-bonding net that supports the enzyme`s antioxidant features.

Los MicroRNAs neuroprotectores en el daño secundario de la lesión medular traumática / Neuroprotective microRNAs in the secondary damage of the traumatic spinal cord injury

Objetivo: Identificar microRNAs cuyos niveles varían específicamente tras una lesión medular traumática. Material y método: en un modelo animal murino (Rattus norvegicus (rata) de la cepa Wistar) se realizó lesión medular mediante contusión, y los fragmentos medulares fueron extraídos a las 24 horas, 3 días y 7 días postlesión. Los patrones de expresión de los animales lesionados se compararon con animales control en los que se realizó laminectomía sin lesión y con un grupo de animales en los que no se realizó ninguna cirugía anterior a la extracción. Resultados: Entre los microRNAs que mostraron una alteración tras la lesión de la médula espinal destaca miR-21, el cual ha sido implicado en el proceso de apoptosis en el sistema nervioso. Conclusión: la lesión de la médula espinal produce alteraciones importantes en los niveles de expresión de microRNAs que participan en los procesos que acontecen en dicha lesión, tales como apoptosis e inflamación (AU)

Aim: Identify microRNAs whose levels change specifically after traumatic spinal cord injury. Materials and methods: in a murine animal model (Rattus norvegicus (rat) Wistar), spinal cord injury was induced by contusion and the medullar fragments were extracted 24 hours, 3 days and 7 days post-injury. The expression patterns of the injured animals were compared with animals that had laminectomy without injury and animals that had no surgery before the extraction. Result: among the microRNAs that change after spinal cord injury it is miR-21 that has been implicated in apoptosis in the nervous system. Conclusion: spinal cord injury causes dramatic changes in the microRNA expression pattern that have a role in the proccesses that take place in the injury as apoptosis and inflamation (AU)

Aberrant expression of tetraspanin molecules in B-cell chronic lymphoproliferative disorders and its correlation with normal B-cell maturation.

Tetraspanin proteins form signaling complexes between them and with other membrane proteins and modulate cell adhesion and migration properties. The surface expression of several tetraspanin antigens (CD9, CD37, CD53, CD63, and CD81), and their interacting proteins (CD19, CD21, and HLA-DR) were analyzed during normal B-cell maturation and compared to a group of 67 B-cell neoplasias. Three patterns of tetraspanin expression were identified in normal B cells. The first corresponded to bone marrow CD10(+) B-cell precursors (BCP) which showed high expression of CD81 and CD9, low reactivity for CD53 and negativity for CD37. CD10(-) B-lymphocytes showed downregulation of CD9/CD81 and upregulation of CD53/CD37. Plasma cells showed re-expressed CD9 and downregulated CD37. Hierarchical clustering analysis of flow cytometry immunophenotypic data showed a good correlation between the tumor differentiation stage and the pattern of tetraspanin expression, with all analyzed individual samples classified into three major groups, independently of their normal or neoplastic origin. Despite this, neoplastic B-cells frequently showed aberrantly high/low expression of the different markers analyzed. Interestingly, in B-cell chronic lymphocytic leukemia, abnormal expression of CD53 and CD9 were associated with different patterns of disease infiltration, which would support the role of these molecules on modulating adhesion and migration of neoplastic B cells.

Differential cooperation between regulatory sequences required for human CD53 gene expression.

CD53 is a tetraspanin protein mostly expressed in to the lymphoid-myeloid lineage. We have characterized the human CD53 gene regulatory region. Within the proximal 2 kilobases, and with opposite transcriptional orientation, is located the promoter-enhancer of a second gene, which does not affect CD53. Twenty-four copies of a CA dinucleotide repeat separate these two gene promoters. The proximal enhanceosome of the human CD53 gene is comprised between residues -266 and +84, and can be subdivided into four major subregions, two of them within exon 1. Mutational analysis identified several cooperating sequences. An Sp1 and an ets-1 site, at positions -115 and +62, respectively, are essential for transcriptional competence in all cell lines. Five other regulatory sequences have a dual role, activator or down-regulator, depending on the cell line. At the end of the non-coding exon 1, +64 to +83, there is a second ets-1 regulatory element, which is required for high level of transcription, in cooperation with the Sp1 site, in K562 and Molt-4, but not in Namalwa cells, where it functions as a repressor. This Sp1 site also cooperates with another ets-1/PU.1 site at -172. Different cell types use different regulatory sequences in the enhanceosome for the expression of the same gene.

Pattern of expression of tetraspanin antigen genes in Burkitt lymphoma cell lines.

Tetraspanin antigens are implicated in the prognosis of different types of tumours. In this study we determine by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) the level of 13 tetraspan messages in 21 Burkitt lymphoma (BL) cell lines. All tumour cell lines have a common pattern of tetraspanin gene expression. There are five antigens which are detected in 90% of cell lines at high levels, CD53, CD81, CD63, SAS and CD82. Another two, CD9 and CD37, were detected in 60% of cell lines, and have a very variable level of expression. The remaining antigens, A15, CoO29, KRAG, L6, TI-1 and il-TMP, are expressed at low levels in very few cell lines without any specific pattern. The level of gene expression corresponds with the level of cell surface antigen determined by flow cytometry. The average number of tetraspan proteins expressed per cell line is six. These proteins may form subunits of an oligomeric structure with 24 transmembrane domains. There are no major differences in tetraspan expression pattern among sporadic or endemic tumours, type of translocation or Epstein-Barr virus status, suggesting the original cell of these tumours is the same, probably a late pre-B cell, at the CD9 to CD37 transition point. Tetraspanin gene expression is consistent with BL being a single entity, despite variations in other parameters.

[Quantitative structure-activity relationship of quinoline derivatives]. / Relación cuantitativa estructura-actividad en algunos derivados de quinoleina.

Quantum-chemical computations using the Hückel method have been performed on quinoline derivatives that exhibit antibacterial activity against E. coli, in order to obtain quantitative structure-activity relationship and drug-receptor interaction data.