Francisco Arenas-Huertero

Reductions in the expression of miR-124-3p, miR-128-1, and miR-221-3p in pediatric astrocytomas are related to high-grade supratentorial, and recurrent tumors in Mexican children

PurposeAstrocytomas are the most frequent type of tumor of the central nervous system in children. Hence, it is important to describe markers that may improve our understanding of their behavior. Mature microRNAs (miRNAs) may be such biological markers. They are small molecules of RNA that regulate gene expression post-transcriptionally. Due to their importance in cancer, the objective of the present study was to determine the profile of expression of precursor and mature forms of miR-124-3p, miR-128-1, and miR-221-3p using RT-qPCR in pediatric samples.MethodsA total of 57 astrocytomas embedded in paraffin were selected. As controls, the study included 13 samples of normal brain tissue.ResultsThree of eight miRNAs were selected after a preliminary screening. All the miRNAs showed higher levels of expression in normal brain tissue. The expression of miR-124-3p and miR-128-1 decreased in astrocytomas than in normal brain tissue in all grades (p < 0.05 in both cases), and this reduction was most evident in GIV (407- and 1,469-fold, respectively); however, the expression of the precursor forms pre-miR-128-1 and pre-miR-221 was higher in GIV (3.5-fold) than in GI. The levels of miR-128-1 were higher in infratentorial tumors than in supratentorial cases (p = 0.006). Finally, the expression of miR-221-3p was higher in non-recurrent tumors and live patients (p = 0.0185 and p = 0.0004, respectively).ConclusionsThe low expression of these miRNAs may constitute a potential marker of astrocytomas that correlates with localization, possibly due to alterations in the maturation processes of these miRNAs that produced low mature forms in patients with recurrent pediatric astrocytomas.

Molecular Markers Associated with the Biological Response to Aromatic Hydrocarbons from Urban Air in Humans

Morbidity and mortality attributable to air pollution continue to be a growing problem in several parts of the world. Both epidemiologic and clinical studies have demonstrated a strong link between exposure to particulate matter (PM) and adverse effects on health. From the PM generated in the atmospheres of several countries, the respirable fraction of PM2.5 (PM2.5) and diesel exhaust particles (DEP) represent some of the largest products of vehicularand industrial-emitted airborne PM that can persist in the air, where they are readily inhaled and deposited throughout the respiratory tract. PM2.5 and DEP have been associated with cardiac and pulmonary alterations. Also, exposure to DEP has been associated with lung cancer, pulmonary inflammation, an increased susceptibility to respiratory infections and the exacerbation of asthma and chronic obstructive pulmonary diseases. Furthermore, the effect of tobacco and its smoke, a complex mixture, represents another source of polycyclic aromatic hydrocarbons (PAH). The three, PM2.5, DEP and tobacco smoke, are the main foci of several studies that evaluate the principal effects of PAH, and represent the via to/source of PAH exposure. Normally, black carbon particles, also products of incomplete fuel combustion, act as condensation nuclei for organic chemicals, such as aromatic aliphatic compounds, including PAH, but they are not considered in this chapter. Rather, this chapter will centre on a molecular description of the cellular responses (AHR pathway) after exposure to PAH from urban air, including relatively new markers, microRNAs and their utility as new biomarkers of exposure to PAH. We propose the use of lung tissue embedded in paraffin as a source of biological material to perform any kind of study: retrospective and prospectives. First, however, an important general description of PAH, its main sources and its concentrations in urban air and their metabolism will be presented in order to contextualize the main objective of this study of molecular markers associated with PAH exposure.

Effects of Sodium Butyrate on Cell Death Induced by Photodynamic Therapy in U373-MG and D54-MG Astrocytoma Cell Lines

The damage induced by end products of photodynamic therapy (PDT) in astrocytoma tumors leads to cytotoxicity and cell death. Chromatin modifiers such as sodium butyrate (NaB) induce several genes involved in apoptosis, among others. The PDT improvement was evaluated by the measurement of its effectiveness in the treatment of U373‐MG and D54‐MG astrocytoma cell lines exposed to NaB. Cells exposed to 80 μg mL−1 of δ‐aminolevulinic acid (ALA) as precursor of endogenous photosensitizer (PS), protoporphyrin IX (PpIX), induced 16.67% and 28.9% of mortality in U373‐MG and D54‐MG, respectively. The mortality increased to 70.62% and 96.7%, respectively, when U373‐MG and D54‐MG cells were exposed for 24 h to 8 mm NaB prior to ALA‐induction. In this condition, re‐expression of some genes related to apoptosis in U373‐MG, and differentiation in D54‐MG were induced. PpIX accumulation was higher than ALA‐induction and the acetylation of histone H4 induced by NaB was verified by immunocytochemistry in both cells. It can be concluded that modified chromatin and genes induced by NaB increment the cellular death induced by PDT in astrocytoma cells using PpIX as endogenous PS.

Brachmann-Cornelia de Lange syndrome with a papilloma of the choroid plexus: analyses of molecular genetic characteristics of the patient and the tumor. A single-case study.

PurposeA 10-month-old girl with a Brachmann-Cornelia de Lange syndrome and a choroid plexus papilloma of the brain was studied at the Hospital Infantil de México Federico Gómez (HIMFG) in Mexico City.Methods and resultsPresumptive papilloma of the third ventricle was evidenced on CT and MR images and removed. Pathological analysis confirmed its origin. A posterior radiosurgery was required due to a tumor relapse. Karyotypes (GTG bands) of the patient and her parents undertaken at HIMFG were normal. Array comparative genomic hybridization (array CGH) analyses of blood DNA of the patient and her parents carried out at BlueGnome’s Laboratory in Cambridge, UK, set in evidence amplification of genes SPNS2, GGT6, SMTNL2, PELP1, MYBBP1A, and ALOX15 in chromosome 17p of the patient. Since MYBBP1A is a proto-oncogene and ALOX15 participates in the development of cancer and metastases of tumors, further fluorescent in situ hybridization (FISH) analyses of these two genes were implemented at HIMFG. Amplification of the two genes was found in the tumor of the case under study but not in an unrelated papilloma of the choroid plexus.DiscussionFurther analyses of the association of choroid plexus papillomas with disorders of psycho-neural development and its relationship to molecular genetic modifications at chromosome 17p are now under way at HIMFG.

Benzo[ghi]perylene activates the AHR pathway to exert biological effects on the NL-20 human bronchial cell line.

Polycyclic aromatic hydrocarbons (PAH) are produced by incomplete combustion of organic material. In the Mexico City atmosphere, the most abundant PAH is benzo[ghi]perylene (BghiP), a gasoline combustion marker. At present, there are no reports of the effects of BghiP on human bronchial cells, so the aim of the study was to evaluate the effects in vitro of BghiP on the NL-20 cell line. Results showed that BghiP induced the formation of small vesicles throughout the cytoplasm, with absence of nuclear fragmentation. At 48h exposition, damage in cell membrane increased significantly at 1.24μg/mL of BghiP (p<0.05). Immunocytochemistry revealed that BghiP provokes nuclear translocation of AhR receptor, which indicates that this compound can induce transcription of genes via receptor binding (AhR pathway activation). BghiP induced a two-fold increase (p<0.05) in the expression of AhR and CYP4B1 (a lung-specific pathway effector). In the presence of the receptor antagonist CH-223191, the loss of viability, the nuclear translocation and the overexpression of genes decreased, though this did not prevent the formation of vesicles. BghiP induced oxidative stress and in presence of the receptor antagonist this increased significantly. In conclusion, BghiP can activate the overexpression of AhR and CYP4B1, and the effects are abated by the AhR receptor antagonist. This is the first report to prove that BghiP utilizes the AhR pathway to exert its toxic effects on the NL-20 human bronchial cell line .

Diversification of the vacAs1m1 and vacAs2m2 Strains of Helicobacter pylori in Meriones unguiculatus

The bacterium Helicobacter pylori exhibits great genetic diversity, and the pathogenic roles of its virulence factors have been widely studied. However, the evolutionary dynamics of H. pylori strains during stomach colonization are not well-characterized. Here, we analyzed the microevolutionary dynamics of the toxigenic strain vacAs1m1, the non-toxigenic strain vacAs2m2, and a combination of both strains in an animal model over time. Meriones unguiculatus were inoculated with the following bacteria: group 1-toxigenic strain vacAs1m1/cagA+/cagE+/babA2+; ST181, group 2-non-toxigenic strain vacAs2m2/cagA+/cagE+/babA2+; ST2901, and group 3-both strains. The gerbils were euthanized at different time points (3, 6, 12, and 18 months). In group 1, genetic alterations were observed at 6 and 12 months. With the combination of both strains, group 3 also exhibited genetic alterations at 3 and 18 months; moreover, a chimera, vacA m1-m2, was detected. Additionally, four new sequence types (STs) were reported in the PubMLST database for H. pylori. Synonymous and non-synonymous mutations were analyzed and associated with alterations in amino acids. Microevolutionary analysis of the STs (PHYLOViZ) identified in each group revealed many mutational changes in the toxigenic (vacAs1m1) and non-toxigenic (vacAs2m2) strains. Phylogenetic assessments (eBURST) did not reveal clonal complexes. Our findings indicate that the toxigenic strain, vacAs1m1, and a combination of toxigenic and non-toxigenic strains acquired genetic material by recombination. The allelic combination, vacAs2m1, displayed the best adaptation in the animal model over time, and a chimera, m1-m2, was also identified, which confirmed previous reports.

Expression of histone acetylases p300 and PCAF in pediatric astrocytomas

ObjectsThe protein 300 (p300) and p300/CBP-binding protein-associated factor (PCAF) are enzymes with histone acetyltransferase (HAT) activity, a function that can become deregulated in different tumors and affect biological responses.MethodsDue to the lack of information on the deregulation of these HATs in pediatric tumors, this study evaluated the expression of both the mRNA and proteins of p300 and PCAF in 54 samples of pediatric astrocytomas embedded in paraffin.ResultsPCAF was not expressed in normal brain tissue. In grade I tumors, the expression of p300 (1.1 ± 0.1) and PCAF (1.2 ± 0.11) was greater than those observed in grade III tumors: 0.72 ± 0.15 for p300 and 0.55 ± 0.11 for PCAF, and grade IV tumors: 0.74 ± 0.13 for p300 and 0.55 ± 0.13 for PCAF (p < 0.05). Immunohistochemical staining revealed the same tendency towards a decrease in the expression of the protein as the degree of clinical severity increased. Patients with recurrent grades I, III, and IV tumors had the highest levels of PCAF, compared to those who showed no recurrence (p < 0.05).ConclusionsThis work describes and confirms that these HATs play important roles in regulating genes and in the biological behavior of pediatric astrocytomas.

Kinetic of the Intracellular Incorporation of New Phthalocyanines Synthesized in mexico and Its Potential as Photosensibilizers in the Photodynamic Therapy

The search of more specific and efficient photosensitizer in low oxygen tensions is a need in the Photodynamic Therapy (PDT). Phthalocyanines have demonstrated to have the above mentioned activity. The aim of this work was to determine the efficiency of PDT using two phthalocyanines synthesized in Mexico to eliminate melanoma cells. B16F0 melanoma mouse cells were exposed to concentrations from 8.95×10−5 to 0.733 m/mL of F16VoPc and F16NbPcC13 during 24h, afterwards cellular mortality was measured. One kinetic was realized to determine the intracellular incorporation of phthalocyanines by confocal microscopy at 1, 2, 4, 8, 16 and 24 h of exposition. The PDT was applied exposing the cells to innocuous concentration (that does not provoke cellular death with out irradiation) and irradiating with an argon laser at 100 J/cm2. For each phthalocyanine a control group was used; one group was not treated neither with light nor with phthalocyanine, the other group it was only irradiated. 24 h after treatment the c...

Induced Protoporphyrin IX Accumulation by the δ‐Aminolevulinic Acid in Bacteria and its Potential Use in the Photodynamic Therapy

The increasing incident of resistant strains to antibiotic has encouraged the search of new antibacterial treatments, such as the photodynamic therapy. In recent years, photodynamic therapy has demonstrated being a good technology for the treatment of recurrent bacteria infection. PDT presents a hopeful approach to eliminate Gram positive and negative bacteria in immunological compromised patients. This therapy uses a laser in combination with a photosensibilizer in presence of intracellular molecular oxygen. The process generates an effect of phototoxicity in bacterial cells.The aim of this work was to determine the in vitro conditions to accumulate PpIX in effective concentrations in Staphylococcus aureus ATCC25923 and Streptococcus pyogenes, which are responsible of human cutaneous diseases. A cellular suspension of both strains was prepared in TSB to obtain growth in Log‐phase, then, the suspensions were adjusted to a final concentration of 2.61×108 cells/mL. The strains were exposed to increasing con...

Expression of miR-210, miR130A, miR-200B in tumors of the adrenal cortex of pediatric patients

&NA; Currently, the diagnosis of adrenocortical tumor behavior in children, cannot be made using the same morphologic criteria used in adult tumors. The lack of application of diagnostic tools with adequate sensitivity and specificity, has promoted research for potential molecular markers to differentiate, by molecular expression, a neoplasm of aggressive behavior from one with benign course. Such is the case of microRNAs that regulate gene expression favoring or inhibiting oncogenesis. At the moment, there are not studies of pediatric adrenocortical neoplasms that have evaluated the differential expression of microRNAs as potential markers of malignant behavior of these tumors, in contrast to what so far has been reported for these tumors in adults. Objective: To describe the pattern of expression of microRNAs-210, 130a, and-200b in adrenocortical neoplasms in children. Methods: Total RNA was extracted from patient adrenocortical tumors and normal adrenal gland (controls) matched for age and sex. MicroRNAs-210, 130a, and 200b were amplified by RT-PCR endpoint in tumors and normal tissues. The expression of micro RNAs in tumors of benign and uncertain biological behavior, malignant tumors and normal tissues, was quantified and compared according to age, sex and clinical response. Results: The sample consisted of 16 cases. The expression of microRNAs in each tumor was evaluated. The expression of microRNA evaluated in tumors was higher than that observed for the controls. There was a statistically significant difference in the expression of miR-130a and miR-200b between tumors and control cases. Conclusions: There is a statistically significant differential expression of miR-130 and miR-200b in adrenocortical tumors in children compared to normal adrenal tissue. The expression of miR-210 in adrenocortical tumors in children was higher than that observed in normal adrenal tissue, although not statistically significant. These three microRNAs may constitute part of the molecular markers could be used to identify an adrenocortical neoplasm malignant behavior in childhood. Further studies are needed to validate these results in another group of pediatric adrenocortical tumors.