Quinolinic Acid, an Endogenous Molecule Combining Excitotoxicity, Oxidative Stress and Other Toxic Mechanisms

Quinolinic acid (QUIN), an endogenous metabolite of the kynurenine pathway, is involved in several neurological disorders, including Huntington’s disease, Alzheimer’s disease, schizophrenia, HIV associated dementia (HAD) etc. QUIN toxicity involves several mechanisms which trigger various metabolic pathways and transcription factors. The primary mechanism exerted by this excitotoxin in the central nervous system (CNS) has been largely related with the overactivation of N-methyl-D-aspartate receptors and increased cytosolic Ca2+ concentrations, followed by mitochondrial dysfunction, cytochrome c release, ATP exhaustion, free radical formation and oxidative damage. As a result, this toxic pattern is responsible for selective loss of middle size striatal spiny GABAergic neurons and motor alterations in lesioned animals. This toxin has recently gained attention in biomedical research as, in addition to its proven excitotoxic profile, a considerable amount of evidence suggests that oxidative stress and energetic disturbances are major constituents of its toxic pattern in the CNS. Hence, this profile has changed our perception of how QUIN-related disorders combine different toxic mechanisms resulting in brain damage. This review will focus on the description and integration of recent evidence supporting old and suggesting new mechanisms to explain QUIN toxicity

Preparation and Characterization of Kynurenic Acid Occluded in Sol-Gel Silica and SBA-15 Silica as Release Reservoirs

Kynurenic acid (KYNA) may have important therapeutic effects in neurological disorders; however, its use as a neuroprotective agent is restricted due to its very limited ability to cross the blood brain barrier (BBB). For this reason, we are looking for new alternatives for KYNA to reach the brain; one of them is using drug delivery systems. To obtain KYNA release reservoirs, KYNA molecules were hosted in two different silica materials. The different KYNA-silica materials were characterized by means of several physical techniques. The spectroscopic studies showed that KYNA molecules remained unchanged once hosted in silica materials. The surface area values of KYNA-silica samples were substantially lower than those for pure silica materials due to the addition of the drug. The electronic micrographs showed that the sol-gel KYNA-silica material consisted of aggregates of nanoparticles around 50 nm in size. On the other hand, the typical SBA-15 hexagonal arrangement was observed, even when hosting KYNA molecules. KYNA release profiles, carried out during approximately 300 hours, showed a first stage of fast drug release followed by a slow release phase. The experimental values fitted to the Peppas equation indicate that the release mechanism was controlled by Fickian diffusion

3-Hydroxykynurenine and 3-Hydroxyanthranilic Acid Enhance the Toxicity Induced by Copper in Rat Astrocyte Culture

Copper is an integral component of various enzymes, necessary for mitochondrial respiration and other biological functions. Excess copper is related with neurodegenerative diseases as Alzheimer and is able to modify cellular redox environment, influencing its functions, signaling, and catabolic pathways. Tryptophan degradation through kynurenine pathway produces some metabolites with redox properties as 3-hydroxykynurenine (3-HK) and 3-hydroxyanthranilic acid (3-HANA). The imbalance in their production is related with some neuropathologies, where the common factors are oxidative stress, inflammation, and cell death. This study evaluated the effect of these kynurenines on the copper toxicity in astrocyte cultures. It assessed the CuSO4 effect, alone and in combination with 3-HK or 3-HANA on MTT reduction, ROS production, mitochondrial membrane potential (MMP), GHS levels, and cell viability in primary cultured astrocytes. Also, the chelating copper effect of 3-HK and 3-HANA was evaluated. The results showed that CuSO4 decreased MTT reduction, MMP, and GSH levels while ROS production and cell death are increasing. Coincubation with 3-HK and 3-HANA enhances the toxic effect of copper in all the markers tested except in ROS production, which was abolished by these kynurenines. Data suggest that 3-HK and 3-HANA increased copper toxicity in an independent manner to ROS production

Role of Kynurenine Pathway in Glioblastoma

In brain, the tryptophan degradation products through the kynurenine pathway exhibit neuromodulatory and inflammatory effects and have been related to the progression of neurodegenerative disorders, furthermore, their protagonism on the modulation of immune response and in cancer development has been reported. The immunosuppressive role of kynurenines has been described on glioblastoma models. In patients, the elevated activity of indoleamine-2,3-dioxygenase (IDO) such as the increase of kynurenine/tryptophan ratio have been also reported, suggesting that activation of kynurenine pathway is present during glioblastoma formation and can be related with tumor progression. The importance of the kynurenine pathway during cancer development has encouraged recent studies to the use of IDO inhibitors as a therapeutic strategy for treatment of breast, lung and ovarian cancer, until to get its use in clinical trials. IDO inhibitors also have been used in in vitro and in vivo models of glioblastoma showing promising results. The effect of kynurenines on glioblastoma offer a new perspective about the tryptophan metabolism during cancer. Due to the relevance of the kynurenine pathway in brain homeostasis, immunomodulation and cancer, we discuss the relevance of the kynurenine pathway on the development of glioblastoma multiforme as well as a possible molecular target for glioblastoma treatment

RB mutation and RAS overexpression induce resistance to NK cell-mediated cytotoxicity in glioma cells

Several theories aim to explain the malignant transformation of cells, including the mutation of tumor suppressors and proto-oncogenes. Deletion of Rb (a tumor suppressor), overexpression of mutated Ras (a proto-oncogene), or both, are sufficient for in vitro gliomagenesis, and these genetic traits are associated with their proliferative capacity. An emerging hallmark of cancer is the ability of tumor cells to evade the immune system. Whether specific mutations are related with this, remains to be analyzed. To address this issue, three transformed glioma cell lines were obtained (Rb(-/-), Ras(V12), and Rb(-/-)/Ras(V12)) by in vitro retroviral transformation of astrocytes, as previously reported. In addition, Ras(V12) and Rb(-/-)/Ras(V12) transformed cells were injected into SCID mice and after tumor growth two stable glioma cell lines were derived. All these cells were characterized in terms of Rb and Ras gene expression, morphology, proliferative capacity, expression of MHC I, Rae1delta, and Rae1alphabetagammadeltaepsilon, mult1, H60a, H60b, H60c, as ligands for NK cell receptors, and their susceptibility to NK cell-mediated cytotoxicity. Our results show that transformation of astrocytes (Rb loss, Ras overexpression, or both) induced phenotypical and functional changes associated with resistance to NK cell-mediated cytotoxicity. Moreover, the transfer of cell lines of transformed astrocytes into SCID mice increased resistance to NK cell-mediated cytotoxicity, thus suggesting that specific changes in a tumor suppressor (Rb) and a proto-oncogene (Ras) are enough to confer resistance to NK cell-mediated cytotoxicity in glioma cells and therefore provide some insight into the ability of tumor cells to evade immune responses.Xunta de GaliciaComisión EuropeaInstituto de Salud Carlos IIIConsejo Nacional de Ciencia y Tecnologia (CONACyT)Consejo Nacional de Ciencia y Tecnologia (CONACyT)FOSSISXunta de Galicia/PXIB208091PRISCIII/CB158340ISCIII/CB180851FOSSIS/18236

Cytotoxicity induced by carbon nanotubes in experimental malignant glioma

"Despite multiple advances in the diagnosis of brain tumors, there is no effective treatment for glioblastoma. Multiwalled carbon nanotubes (MWCNTs), which were previously used as a diagnostic and drug delivery tool, have now been explored as a possible therapy against neoplasms. However, although the toxicity profile of nanotubes is dependent on the physicochemical characteristics of specific particles, there are no studies exploring how the effectivity of the carbon nanotubes (CNTs) is affected by different methods of production. In this study, we characterize the structure and biocompatibility of four different types of MWCNTs in rat astrocytes and in RG2 glioma cells as well as the induction of cell lysis and possible additive effect of the combination of MWCNTs with temozolomide. We used undoped MWCNTs (labeled simply as MWCNTs) and nitrogen-doped MWCNTs (labeled as N-MWCNTs). The average diameter of both pristine MWCNTs and pristine N-MWCNTs was ~22 and ~35 nm, respectively. In vitro and in vivo results suggested that these CNTs can be used as adjuvant therapy along with the standard treatment to increase the survival of rats implanted with malignant glioma.

Suppression of cell migration is promoted by miR-944 through targeting of SIAH1 and PTP4A1 in breast cancer cells

Background: Aberrant expression of microRNAs has been associated with migration of tumor cells. In this study, we aimed to investigate the biological significance of miR-944 whose function is unknown in breast cancer. Methods: MiR-944 expression in breast cancer cells and tumors was evaluated by Taqman qRT-PCR assays. Transcriptional profiling of MDA-MB-231 cells expressing miR-944 was performed using DNA microarrays. Cell viability, migration and invasion were assessed by MTT, scratch/wound-healing and transwell chamber assays, respectively. The luciferase reporter assay was used to evaluate targeting of SIAH1, PTP4A1 and PRKCA genes by miR-944. SIAH1 protein levels were measured by Western blot. Silencing of SIAH1 gene was performed by RNA interference using shRNAs. Results: Our data showed that miR-944 expression was severely repressed in clinical specimens and breast cancer cell lines. Suppression of miR-944 levels was independent of hormonal status and metastatic potential of breast cancer cells. Gain-of-function analysis indicated that miR-944 altered the actin cytoskeleton dynamics and impaired cell migration and invasion. Genome-wide transcriptional profiling of MDA-MB-231 cells that ectopically express miR-944 showed that 15 genes involved in migration were significantly repressed. Notably, luciferase reporter assays confirmed the ability of miR-944 to bind the 3´UTR of SIAH1 and PTP4A1 genes, but not PRKCA gene. Congruently, an inverse correlation between miR-944 and SIAH1 protein expression was found in breast cancer cells. Moreover, SIAH1 was upregulated in 75 % of miR-944-deficient breast tumors. Finally, SIAH1 gene silencing by RNA interference significantly impaired cell migration of breast cancer cells. Conclusions: Our results pointed out that miR-944 is a novel upstream negative regulator of SIAH1 and PTP4A1 genes and provided for the first time evidence for its functional role in migration and invasion of breast cancer cells. They also suggest that miR-944 restoration may represent a potential strategy for breast cancer therapy

Reflexiones desde la enseñanza y el aprendizaje de la arquitectura

DOCEO nace como una idea del Decano del Departamento de Arquitectura y Diseño de la Universidad de la Costa, Samuel Padilla-Llano para divulgar todos los procesos creativos y las experiencias exitosas en el noble ejercicio de enseñanza y aprendizaje de la Arquitectura y el Diseño que se dan a través de las dinámicas en el Aula

Multicentric study of cervical cancer screening with human papillomavirus testing and assessment of triage methods in Latin America : the ESTAMPA screening study protocol

Q1Q1Introduction Human papillomavirus (HPV) testing is replacing cytology in primary screening. Its limited specificity demands using a second (triage) test to better identify women at high-risk of cervical disease. Cytology represents the immediate triage but its low sensitivity might hamper HPV testing sensitivity, particularly in low-income and middle-income countries (LMICs), where cytology performance has been suboptimal. The ESTAMPA (EStudio multicéntrico de TAMizaje y triaje de cáncer de cuello uterino con pruebas del virus del PApiloma humano; Spanish acronym) study will: (1) evaluate the performance of different triage techniques to detect cervical precancer and (2) inform on how to implement HPV-based screening programmes in LMIC. Methods and analysis Women aged 30–64 years are screened with HPV testing and Pap across 12 study centres in Latin America. Screened positives have colposcopy with biopsy and treatment of lesions. Women with no evident disease are recalled 18 months later for another HPV test; those HPV-positive undergo colposcopy with biopsy and treatment as needed. Biological specimens are collected in different visits for triage testing, which is not used for clinical management. The study outcome is histological high-grade squamous intraepithelial or worse lesions (HSIL+) under the lower anogenital squamous terminology. About 50 000 women will be screened and 500 HSIL+ cases detected (at initial and 18 months screening). Performance measures (sensitivity, specificity and predictive values) of triage techniques to detect HSIL+ will be estimated and compared with adjustment by age and study centre. Ethics and dissemination The study protocol has been approved by the Ethics Committee of the International Agency for Research on Cancer (IARC), of the Pan American Health Organisation (PAHO) and by those in each participating centre. A Data and Safety Monitoring Board (DSMB) has been established to monitor progress of the study, assure participant safety, advice on scientific conduct and analysis and suggest protocol improvements. Study findings will be published in peer-reviewed journals and presented at scientific meetings. Trial registration number NCT01881659Revista Internacional - Indexad