Metabolic dysregulation of tricarboxylic acid cycle and oxidative phosphorylation in glioblastoma.

Glioblastoma multiforme (GBM) exhibits genetic alterations that induce the deregulation of oncogenic pathways, thus promoting metabolic adaptation. The modulation of metabolic enzyme activities is necessary to generate nucleotides, amino acids, and fatty acids, which provide energy and metabolic intermediates essential for fulfilling the biosynthetic needs of glioma cells. Moreover, the TCA cycle produces intermediates that play important roles in the metabolism of glucose, fatty acids, or non-essential amino acids, and act as signaling molecules associated with the activation of oncogenic pathways, transcriptional changes, and epigenetic modifications. In this review, we aim to explore how dysregulated metabolic enzymes from the TCA cycle and oxidative phosphorylation, along with their metabolites, modulate both catabolic and anabolic metabolic pathways, as well as pro-oncogenic signaling pathways, transcriptional changes, and epigenetic modifications in GBM cells, contributing to the formation, survival, growth, and invasion of glioma cells. Additionally, we discuss promising therapeutic strategies targeting key players in metabolic regulation. Therefore, understanding metabolic reprogramming is necessary to fully comprehend the biology of malignant gliomas and significantly improve patient survival.

Role of Glycolytic and Glutamine Metabolism Reprogramming on the Proliferation, Invasion, and Apoptosis Resistance through Modulation of Signaling Pathways in Glioblastoma.

Glioma cells exhibit genetic and metabolic alterations that affect the deregulation of several cellular signal transduction pathways, including those related to glucose metabolism. Moreover, oncogenic signaling pathways induce the expression of metabolic genes, increasing the metabolic enzyme activities and thus the critical biosynthetic pathways to generate nucleotides, amino acids, and fatty acids, which provide energy and metabolic intermediates that are essential to accomplish the biosynthetic needs of glioma cells. In this review, we aim to explore how dysregulated metabolic enzymes and their metabolites from primary metabolism pathways in glioblastoma (GBM) such as glycolysis and glutaminolysis modulate anabolic and catabolic metabolic pathways as well as pro-oncogenic signaling and contribute to the formation, survival, growth, and malignancy of glioma cells. Also, we discuss promising therapeutic strategies by targeting the key players in metabolic regulation. Therefore, the knowledge of metabolic reprogramming is necessary to fully understand the biology of malignant gliomas to improve patient survival significantly.

Crosstalk of the Wnt/ß-Catenin Signaling Pathway in the Induction of Apoptosis on Cancer Cells.

The Wnt/ß-catenin signaling pathway plays a major role in cell survival and proliferation, as well as in angiogenesis, migration, invasion, metastasis, and stem cell renewal in various cancer types. However, the modulation (either up- or downregulation) of this pathway can inhibit cell proliferation and apoptosis both through ß-catenin-dependent and independent mechanisms, and by crosstalk with other signaling pathways in a wide range of malignant tumors. Existing studies have reported conflicting results, indicating that the Wnt signaling can have both oncogenic and tumor-suppressing roles, depending on the cellular context. This review summarizes the available information on the role of the Wnt/ß-catenin pathway and its crosstalk with other signaling pathways in apoptosis induction in cancer cells and presents a modified dual-signal model for the function of ß-catenin. Understanding the proapoptotic mechanisms induced by the Wnt/ß-catenin pathway could open new therapeutic opportunities.

Anti-proliferative, pro-apoptotic and anti-invasive effect of the copper coordination compound Cas III-La through the induction of reactive oxygen species and regulation of Wnt/ß-catenin pathway in glioma.

Gliomas are the most aggressive neoplasms that affect the central nervous system, being glioblastoma multiforme (GBM) the most malignant. The resistance of GBM to therapies is attributed to its high rate of cell proliferation, angiogenesis, invasion, and resistance to apoptosis; thus, finding alternative therapeutic approaches is vital. In this work, the anti-proliferative, pro-apoptotic, and anti-invasive effect of the copper coordination compound Casiopeina III-La (Cas III-La) on human U373 MG cells was determined in vitro and in vivo. Our results indicate that Cas III-La exerts an anti-proliferative effect, promoting apoptotic cell death and inactivating the invasive process by generating reactive oxygen species (ROS), inactivating GSK3ß, activating JNK and ERK, and promoting the nuclear accumulation of ß-catenin. The inhibition of ROS generation by N-acetyl-l-cysteine not only recovered cell migration and viability, but also reduced ß-catenin accumulation and JNK and ERK activation. Additionally, Cas III-La significantly reduced tumor volume, cell proliferation and mitotic indices, and increased the apoptotic index in mice xenotransplanted with U373 glioma cells. Thus, Cas III-La is a promising agent to treat GBM.

Autophagy as a Potential Therapy for Malignant Glioma.

Glioma is the most frequent and aggressive type of brain neoplasm, being anaplastic astrocytoma (AA) and glioblastoma multiforme (GBM), its most malignant forms. The survival rate in patients with these neoplasms is 15 months after diagnosis, despite a diversity of treatments, including surgery, radiation, chemotherapy, and immunotherapy. The resistance of GBM to various therapies is due to a highly mutated genome; these genetic changes induce a de-regulation of several signaling pathways and result in higher cell proliferation rates, angiogenesis, invasion, and a marked resistance to apoptosis; this latter trait is a hallmark of highly invasive tumor cells, such as glioma cells. Due to a defective apoptosis in gliomas, induced autophagic death can be an alternative to remove tumor cells. Paradoxically, however, autophagy in cancer can promote either a cell death or survival. Modulating the autophagic pathway as a death mechanism for cancer cells has prompted the use of both inhibitors and autophagy inducers. The autophagic process, either as a cancer suppressing or inducing mechanism in high-grade gliomas is discussed in this review, along with therapeutic approaches to inhibit or induce autophagy in pre-clinical and clinical studies, aiming to increase the efficiency of conventional treatments to remove glioma neoplastic cells.

Autophagic and Apoptotic Pathways as Targets for Chemotherapy in Glioblastoma.

Glioblastoma multiforme is the most malignant and aggressive type of brain tumor, with a mean life expectancy of less than 15 months. This is due in part to the high resistance to apoptosis and moderate resistant to autophagic cell death in glioblastoma cells, and to the poor therapeutic response to conventional therapies. Autophagic cell death represents an alternative mechanism to overcome the resistance of glioblastoma to pro-apoptosis-related therapies. Nevertheless, apoptosis induction plays a major conceptual role in several experimental studies to develop novel therapies against brain tumors. In this review, we outline the different components of the apoptotic and autophagic pathways and explore the mechanisms of resistance to these cell death pathways in glioblastoma cells. Finally, we discuss drugs with clinical and preclinical use that interfere with the mechanisms of survival, proliferation, angiogenesis, migration, invasion, and cell death of malignant cells, favoring the induction of apoptosis and autophagy, or the inhibition of the latter leading to cell death, as well as their therapeutic potential in glioma, and examine new perspectives in this promising research field.

In vitro evaluation of apoptotic effect of bis(acetylacetonato-k2 O,O')(1,10-phenanthroline-k2 N,N')Zn(II) complex.

Phenanthroline derivatives have been reported as potential bioactive compounds because of their ability to interact with DNA. To evaluate the antiproliferative effect of bis(acetylacetonate-k2 O,O)(1,10-phenanthroline-k2 N,N)Zn(II) or Zn(acac)2 (phen) complex, the compound was obtained in a simple manner and further characterized to determine crystal structure, thermal behavior, morphology, and spectroscopic properties. The structure of the complex was confirmed by X-ray single structure as well as by 1H and 13C nuclear magnetic resonance (NMR) in dmso-d6 (dimethyl sulfoxide) solution and in the solid state by 13C CP/MAS. Although preparation of this compound has been described previously, there are no reports on its biological activity; here, we assessed its antiproliferative effect on fibroblasts, A253, FaDu, Cal-27, RH-30, RD, U-373, C6, A-549, MDA-MB-231, and MCF-7 cancer cell lines at different doses (50-100 and 150 µg/ml). The cell viability was determined by MTT assay and high activity was observed for the most of the cell lines, and TUNEL results showed the induction of apoptosis.

[Preventive and remineralization effect over incipient lesions of caries decay by phosphopeptide-amorphous calcium phosphate]. / Efecto preventivo y de remineralizacion de caries incipientes del fosfopeptido de caseina fosfato de calcio amorfo.

INTRODUCTION. Dental caries continues to affect a large percentage of Mexican children and currently advises that if diagnosed at an early stage can be reversed with minimally invasive treatments. The casein phosphopeptide amorphous calcium phosphate known as CPP-ACP is a phosphoprotein capable of releasing calcium and phosphate ions in the oral environment promoting remineralization. OBJECTIVE. To evaluate the effect of CPP-ACP with fluoride added in a scholar preventive program. MATERIAL AND METHODS. A cuasi- experimental study was conducted in 104 schools of six years old. The children were classified into three groups and received six months biweekly applications of different treatments: casein phosphopeptide amorphous calcium phosphate added fluoride (CPP-ACPF), sodium fluoride (NaF) and a control group. Clinical evaluation was performed with the laser fluorescence technique (Diagnodent model 2095). 1340 teeth were included: 294 teeth with incipient lesions and 1,046 healthy teeth. Statistical tests of χ2 y Mc Nemar were used. RESULTS. In the group that received the application of CPP-ACPF, 38% of incipient carious lesions were remineralizing compared with 21% in the group receiving the NaF (p < 0.001) and 15% in the control group (p < 0.0001) The percentage of teeth free of caries were preserved in the therapy group phosphoprotein was the biggest. This group also showed the lower proportion of deep carious lesion development (p < 0.0001). CONCLUSION. The application biweekly for six months of CPP-ACPF showed a protective and remineralizing effect on incipient carious lesions. His action was better than the application of NaF. However, to reduce the impact from dental caries in schoolchildren is important to have a comprehensive preventive approach that includes promoting self-care, as well as the application of sealants.

Multiple molecular and cellular mechanisms of action of lycopene in cancer inhibition.

Epidemiological studies suggest that including fruits, vegetables, and whole grains in regular dietary intake might prevent and reverse cellular carcinogenesis, reducing the incidence of primary tumours. Bioactive components present in food can simultaneously modulate more than one carcinogenic process, including cancer metabolism, hormonal balance, transcriptional activity, cell-cycle control, apoptosis, inflammation, angiogenesis and metastasis. Some studies have shown an inverse correlation between a diet rich in fruits, vegetables, and carotenoids and a low incidence of different types of cancer. Lycopene, the predominant carotenoid found in tomatoes, exhibits a high antioxidant capacity and has been shown to prevent cancer, as evidenced by clinical trials and studies in cell culture and animal models. In vitro studies have shown that lycopene treatment can selectively arrest cell growth and induce apoptosis in cancer cells without affecting normal cells. In vivo studies have revealed that lycopene treatment inhibits tumour growth in the liver, lung, prostate, breast, and colon. Clinical studies have shown that lycopene protects against prostate cancer. One of the main challenges in cancer prevention is the integration of new molecular findings into clinical practice. Thus, the identification of molecular biomarkers associated with lycopene levels is essential for improving our understanding of the mechanisms underlying its antineoplastic activity.

Copper compound induces autophagy and apoptosis of glioma cells by reactive oxygen species and JNK activation.

BACKGROUND: Glioblastoma multiforme (GBM) is the most aggressive of the primary brain tumors, with a grim prognosis despite intensive treatment. In the past decades, progress in research has not significantly increased overall survival rate. METHODS: The in vitro antineoplastic effect and mechanism of action of Casiopeina III-ia (Cas III-ia), a copper compound, on rat malignant glioma C6 cells was investigated. RESULTS: Cas III-ia significantly inhibited cell proliferation, inducing autophagy and apoptosis, which correlated with the formation of autophagic vacuoles, overexpression of LC3, Beclin 1, Atg 7, Bax and Bid proteins. A decrease was detected in the mitochondrial membrane potential and in the activity of caspase 3 and 8, together with the generation of intracellular reactive oxygen species (ROS) and increased activity of c-jun NH(2)-terminal kinase (JNK). The presence of 3-methyladenine (as selective autophagy inhibitor) increased the antineoplastic effect of Cas III-ia, while Z-VAD-FMK only showed partial protection from the antineoplastic effect induced by Cas III-ia, and ROS antioxidants (N-acetylcysteine) decreased apoptosis, autophagy and JNK activity. Moreover, the JNK -specific inhibitor SP600125 prevented Cas III-ia-induced cell death. CONCLUSIONS: Our data suggest that Cas III-ia induces cell death by autophagy and apoptosis, in part due to the activation of ROS -dependent JNK signaling. These findings support further studies of Cas III-ia as candidate for treatment of human malignant glioma.

[Fluoride urinary excretion in Mexico City's preschool children]. / Excreción urinaria de flúor por preescolares en la ciudad de México.

OBJECTIVE: The assessment of urinary fluoride excretion during dental developing stage has been reported for different countries with community fluoride programs. Also, one of the factors that could influence on retention and excretion of fluoride is the deficient nutrition so the aim of this study was to determine fluoride urinary excretion by a group of preschool children with and without malnutrition. MATERIALS AND METHODS: Urinary samples from 24 hours were collected from 60 preschool children selected by convenience from Iztapalapa area of Mexico City, 30 with malnutrition and 30 with standard nutritrional status by weight for age. The samples were analyzed by fluoride especific electrode. Orion 720A. RESULTS: The average concentration of fluoride in urine from preschool children with and without malnutrition were 0.89 +/- 0.4 mg/L and 0.80 +/- 0.3 mg/L, respectively. The mean of 24 hours total fluoride excreted were 367 +/- 150 microg/24 hrs. in malnutrition children and 355 +/- 169 microg/24 hrs. for those with standard nutritional status. There were no differences statistically significant between groups. CONCLUSION: The urinary fluoride excretion for children with and without malnutrition were in the optimal range of fluoridation for the prevention of caries decay. Malnutrition was no associated with changes on fluoride orine concentration and excretion rates.

Immunoexpression of the HLA-DR class II molecule in cells from inflamed dental pulp.

BACKGROUND: Despite that the role of inflammatory cells in chronic inflammatory reactions of pulpal origin (CIRPOs) has been extensively studied, function of the HLA-DR+ cells (HLA-DR+ Cs) is poorly understood. The aim of this study was to quantify their number and clarify their role in these lesions. METHODS: We studied 11 CIRPOs immunostained with an anti-HLA-DR class II monoclonal antibody and the number and location of the HLA-DR+ Cs quantified. CIRPOs were divided in periapical granulomas (PGs), epithelized granulomas (EGs) and periapical cysts (PCs). RESULTS: HLA-DR+ Cs were observed within epithelium, inflammatory infiltrate and close to blood vessels. In PGs, they account for 19-256 cells/mm2, in EGs they were 20-494 cells/mm2 and in PCs quantification numbered 39-316 cells/mm2. CONCLUSIONS: Our results suggest that HLA-DR+ Cs present antigens to lymphocytes, collaborating in initiation, regulation, development and perpetuation of CIRPOs. Also, these results suggest that these cells have an active role during initiation of epithelial proliferation in PGs and that they are partially responsible for cystic transformation from EGs to periapical cysts. They may also play an active role in bone resorption.

Alteration of the sialylation pattern of the murine tooth germ after ethanol exposure.

BACKGROUND: Ethanol consumption during pregnancy leads to changes in murine dental morphogenesis, dental size, cellular differentiation, enamel mineralization, and delayed eruption. It has been proposed that glycoproteins play a role during embryonic dental development that may determine the dental morphological pattern and extracellular matrix secretion. O-glycosylation and sialylation appear to actively participate in the differentiation and maturation processes. Because glycosylation may be affected by teratogens that can alter the maturation of several organisms, in this work we describe the main modifications of the sialylation pattern in prenatal day (PD) 18.5 murine tooth germs exposed to ethanol. METHODS: Pregnant female mice were divided into groups that were given 15% or 20% ethanol solutions, or water as a control. The histochemistry of tooth germs from PD 18.5 fetuses was revealed with lectins specific for sialic acid (Neu5Ac), such as Sambucus nigra (SNA), Maackia amurensis (MAA), and Machrobrachium rosenbergii (MRL), and for sialylated-O-glycosidically linked glycans, such as Amaranthus leucocarpus (ALL). RESULTS: The basement membrane, preameloblasts, inner-enamel epithelium, preodontoblasts, and subodontoblastic cells of the test groups showed changes in labeling according to the 4 lectins used. Intranuclear staining was observed with SNA (specific for Neu5Acalpha2,6Gal/GalNAc) in the control group, but this was reduced in the test groups. The nuclei of dental papillary cells under the experimental conditions were stained with MAA (Neu5Acalpha2,3Gal). CONCLUSIONS: Dental development involves different types of sialylated O-glycosidically linked glycans that are likely to regulate cell-to-cell and cell-to-matrix interactions. Our results suggest that ethanol consumption during pregnancy alters the sialylation pattern during murine dental morphogenesis.

EGF-R and erbB-2 in murine tooth development after ethanol exposure.

BACKGROUND: Alcohol consumption during pregnancy can frequently lead to a congenital disorder known as fetal alcohol syndrome (FAS); however, not all children born to alcoholic women develop FAS. Alcohol consumption may affect diverse organs and systems during embryonic development, including craniofacial structures. Small teeth, enamel alterations, and delayed eruption have been observed after ethanol exposure. Epidermal growth factor receptors (EGF-Rs) participate in dental proliferation and differentiation, and changes in these receptors were considered here to be a likely mechanism associated to the dental anomalies observed in this syndrome. Epidermal growth factor receptor type 1 (EGF-R) and epidermal growth factor receptor type 2 (erbB-2) immunoexpression during the lower first molar morphogenesis was investigated in mouse fetuses exposed to ethanol during gestation. METHODS: Pregnant female mice were divided into groups, consuming either 5, 10, 15, 20, or 25% ethanol solutions, or water (control group). Heads were obtained from 16.5- and 18.5-day fetuses. Immunohistochemistry was applied to EGF-R and erbB-2. RESULTS: At days 16.5 and 18.5, fetuses from 15%, 20%, and 25% ethanol groups showed delayed differentiation, degenerative changes in dental epithelial tissues and reduced dental size; additionally, they displayed an enhanced immunoreactivity to EGF-R and erbB-2. CONCLUSIONS: Our results suggest that ethanol consumption during pregnancy affects the expression of EGF receptors and induces a delay in murine fetal dental morphogenesis. Dental development is a process that involves a number of growth factors; hence we consider that further research is required to show whether the changes in glycosylation and growth-factor signaling pathways observed in other cells are also involved in the alterations observed in this study.

[Prevalence of Dental Fluorosis and Caries in Mexico City Schoolchildren]. / Prevalencia de fluorosis dental y caries en escolares de la ciudad de México.

UNLABELLED: This study was conducted to determine prevalence and severity of dental fluorosis and dental caries in school-children living in two zones of the Mexico City's East Area. METHODS: Fluorosis and caries scores were recorded for 1,569 children according to the Dean Community Index, DMFT and DMFS indexes, and the relationship between fluorosis and fluoride sources was investigated. RESULTS: Dental fluorosis was found in 60.42% of children. Dean's Community score was 0.96 (SD-0.58). Quantity of toothpaste employed, toothbrushing frequency, and early initiation of toothbrushing correlated well with fluorosis (p = 0.03). Caries was present in 70.52% of children, DMFT and DMFS scores were 2.64 (SD 2.4) and 3.97 (SD 4.18) respectively. DMFT and DMFS scores were lower in children with mild and moderate fluorosis than in those fluorosis-free children. (p = 0.03).