Glioma and Peptidergic Systems: Oncogenic and Anticancer Peptides

Glioma cells overexpress different peptide receptors that are useful for research, diagnosis, management, and treatment of the disease. Oncogenic peptides favor the proliferation, migration, and invasion of glioma cells, as well as angiogenesis, whereas anticancer peptides exert antiproliferative, antimigration, and anti-angiogenic effects against gliomas. Other peptides exert a dual effect on gliomas, that is, both proliferative and antiproliferative actions. Peptidergic systems are therapeutic targets, as peptide receptor antagonists/peptides or peptide receptor agonists can be administered to treat gliomas. Other anticancer strategies exerting beneficial effects against gliomas are discussed herein, and future research lines to be developed for gliomas are also suggested. Despite the large amount of data supporting the involvement of peptides in glioma progression, no anticancer drugs targeting peptidergic systems are currently available in clinical practice to treat gliomas.

Effect of amisulpride on the expression of serotonin receptors, neurotrophic factor BDNF and its receptors in mice with overexpression of the aggregation-prone [R406W] mutant tau protein

Serotonin 5-HT7 receptors (5-HT7R) are attracting increasing attention as important participants in the mechanisms of Alzheimer's disease and as a possible target for the treatment of various tau pathologies. In this study, we investigated the effects of amisulpride (5-HT7R inverse agonist) in C57BL/6J mice with experimentally induced expression of the gene encoding the aggregation-prone human Tau[R406W] protein in the prefrontal cortex. In these animals we examined short-term memory and the expression of genes involved in the development of tauopathy (Htr7 and Cdk5), as well as biomarkers of neurodegenerative processes - the Bdnf gene and its receptors TrkB (the Ntrk2 gene) and p75NTR (the Ngfr gene). In a short-term memory test, there was no difference in the discrimination index between mice treated with AAV-Tau[R406W] and mice treated with AAV-EGFP. Amisulpride did not affect this parameter. Administration of AAV-Tau[R406W] resulted in increased expression of the Htr7, Htr1a, and Cdk5 genes in the prefrontal cortex compared to AAV-EGFP animals. At the same time, amisulpride at the dose of 10 mg/kg in animals from the AAV-Tau[R406W] group caused a decrease in the Htr7, Htr1a genes mRNA levels compared to animals from the AAV-Tau[R406W] group treated with saline. A decrease in the expression of the Bdnf and Ntrk2 genes in the prefrontal cortex was revealed after administration of AAV-Tau[R406W]. Moreover, amisulpride at various doses (3 and 10 mg/kg) caused the same decrease in the transcription of these genes in mice without tauopathy. It is also interesting that in mice of the AAV-EGFP group, administration of amisulpride at the dose of 10 mg/kg increased the Ngfr gene mRNA level. The data obtained allow us to propose the use of amisulpride in restoring normal tau protein function. However, it should be noted that prolonged administration may result in adverse effects such as an increase in Ngfr expression and a decrease in Bdnf and Ntrk2 expression, which is probably indicative of an increase in neurodegenerative processes.

Mini review of molecules involved in altered postnatal neurogenesis in autism

The neurobiology of autism is complex, but emerging research points to potential abnormalities and alterations in neurogenesis. The aim of the present review is to describe the advances in the understanding of the role of selected neurotrophins, neuropeptides, and other compounds secreted by neuronal cells in the processes of postnatal neurogenesis in conjunction with autism. We characterize the fundamental mechanisms of neuronal cell proliferation, generation of major neuronal cell types with special emphasis on neurogenic niches - the subventricular zone and hippocampal areas. We also discuss changes in intracellular calcium levels and calcium-dependent transcription factors in the context of the regulation of neurogenesis and cell fate determination. To sum up, this review provides specific insight into the known association between alterations in the function of the entire spectrum of molecules involved in neurogenesis and the etiology of autism pathogenesis.

Identification of co-expressed gene networks promoting CD8+ T cell infiltration and having prognostic value in uveal melanoma

Current immunotherapies are unsatisfactory against uveal melanoma (UM); however, elevated CD8+ T cell infiltration level indicates poor prognosis in UM. Here, we aimed to identify co-expressed gene networks promoting CD8+ T cell infiltration in UM and created a prognostic hazard model based on the identified hub genes. Raw data and clinical information were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Stromal-immune comprehensive score (ESTIMATE) was used to evaluate the immune-infiltration landscape of the tumor microenvironment. Single-Sample Gene Set Enrichment Analysis (ssGSEA) and Weighted Correlation Network Analysis (WGCNA) were used to quantify CD8+ T cell infiltration level and identify hub genes. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to analyze the biological processes. Least absolute shrinkage and selection operator (LASSO) Cox regression were used to establish a prognostic model, which was further validated. Finally, pan-cancer analysis evaluated these genes to be associated with CD8+ T cell infiltration in other tumors. In conclusion, the proposed four-gene (PTPN12, IDH2, P2RX4, and KDELR2) prognostic hazard model had satisfactory prognostic ability. These hub genes may promote CD8+ T cell infiltration in UM through antigen presentation, and CD8+ T cell possibly function as Treg, resulting in poor prognosis. These findings might facilitate the development of novel immunotherapies.

Pituitary Adenylate Cyclase-Activating Polypeptide Protects Against Cognitive Impairment Caused by Chronic Cerebral Hypoperfusion

BACKGROUND

Pituitary adenylate cyclase-activating polypeptide (PACAP) has beneficial effects in learning and memory. However, the mechanism by which PACAP improves cognitive impairment of vascular dementia (VaD) is not clear.

METHODS

We established a VaD model by bilateral common carotid stenosis (BCAS) to investigate the molecular mechanism of cognitive impairment. Protein levels of PACAP, Sirtuin 3 (Sirt3), brain-derived neurotrophic factor (BDNF), and postsynaptic density 95 (PSD-95) were assessed by Western blot. In vitro, oxygen glucose deprivation (OGD) was used to simulate the ischemia/hypoxia state. HT22 cells were transfected with Sirt3 knockdown and overexpression to study the relationship between PACAP, Sirt3, and BDNF. In vivo, PACAP was administered intranasally to assess its protective effects on BCAS.

RESULTS

The study showed that the levels of PACAP, Sirt3, BDNF, and PSD-95 were decreased in the BCAS model of VaD. PACAP increased the protein levels of Sirt3, BDNF, PSD-95, Bcl-2, and Bax under OGD condition in vitro. Sirt3 regulated BDNF and synaptic plasticity. Intranasal PACAP increased the protein levels of PAC1, Sirt3, BDNF, and PSD-95 in vivo.

CONCLUSIONS

This study provides evidence that PACAP regulates synaptic plasticity and plays an antiapoptotic role through Sirt3.

A Fragrant Environment Containing α-Pinene Suppresses Tumor Growth in Mice by Modulating the Hypothalamus/Sympathetic Nerve/Leptin Axis and Immune System

The environment is thought to affect outcomes in patients with cancer; however, this relationship has not been proven directly. Recently, an enriched environment, as a model of a positive environment, has been shown to suppress tumor growth by lowering leptin production through a pathway involving the hypothalamus/sympathetic nerve/leptin axis. We previously reported that a fragrant environment (FE) containing α-pinene suppressed tumor growth in mice; however, the underlying mechanism has not been elucidated. Accordingly, in this study, we investigated changes in the neuroendocrine and immune systems following exposure to an FE. Mice were exposed to α-pinene (5 h/day) for 4 weeks prior to tumor implantation with murine melanoma cells and 3 weeks after transplantation. In addition to the evaluation of tumor growth, the blood, spleen, and hypothalamus were collected 3 weeks after transplantation, and neuroendocrinological and immunological parameters were measured. Tumor size was ~40% smaller in mice exposed to FE. Moreover, plasma noradrenaline concentrations, which reflected sympathetic nervous activity, tended to increase, and leptin levels were significantly decreased in FE-exposed mice. Levels of stress hormones, such as plasma corticosterone and adrenaline, did not change in the 2 groups. In the hypothalamus, brain-derived neurotrophic factor protein levels and glucose-1-phosphate concentrations were decreased in the FE group. Additionally, numbers of B cells, CD4⁺ T cells, CD8⁺ T cells, and natural killer cells increased in the FE-exposed mice. These neurohormonal and immunological changes in the FE-exposed mice suggested that the FE may activate the hypothalamus/sympathetic nerve/leptin axis and immune system, thereby retarding tumor growth.

Emerging therapeutic potential of anti-psychotic drugs in the management of human glioma: A comprehensive review

Despite numerous advancements in the last decade, human gliomas such as astrocytoma and glioblastoma multiforme have the worst prognoses among all cancers. Anti-psychotic drugs are commonly prescribed to treat mental disorders among cancer patients, and growing empirical evidence has revealed their antitumor, anti-metastatic, anti-angiogenic, anti-proliferative, chemo-preventive, and neo-adjuvant efficacies in various in vitro, in vivo, and clinical glioma models. Anti-psychotic drugs have drawn the attention of physicians and researchers owing to their beneficial effects in the prevention and treatment of gliomas. This review highlights data on the therapeutic potential of various anti-psychotic drugs as anti-proliferative, chemopreventive, and anti-angiogenic agents in various glioma models via the modulation of upstream and downstream molecular targets involved in apoptosis, autophagy, oxidative stress, inflammation, and the cell cycle in in vitro and in vivo preclinical and clinical stages among glioma patients. The ability of anti-psychotic drugs to modulate various signaling pathways and multidrug resistance-conferring proteins that enhance the efficacy of chemotherapeutic drugs with low side-effects exemplifies their great potential as neo-adjuvants and potential chemotherapeutics in single or multimodal treatment approach. Moreover, anti-psychotic drugs confer the ability to induce glioma into oligodendrocyte-like cells and neuronal-like phenotype cells with reversal of epigenetic alterations through inhibition of histone deacetylase further rationalize their use in glioma treatment. The improved understanding of anti-psychotic drugs as potential chemotherapeutic drugs or as neo-adjuvants will provide better information for their use globally as affordable, well-tolerated, and effective anticancer agents for human glioma.

P2X4R silence suppresses glioma cell growth through BDNF/TrkB/ATF4 signaling pathway

Purinergic receptor P2X 4 (P2X4R), a member of purinergic channels family and a subtype of ionotropic adenosine triphosphate receptors, plays a critical role in tumorigenesis. Evidence suggested that P2X4R is expressed in rat C6 glioma model, however, its role and the underlying mechanism of action are still unclear in human glioblastoma multiforme (GBM). In the current study, our aim is to examine the function and the molecular basis of P2X4R in GBM. We first observed that GBM cells, U251, T98, U87, U373, and A172 were all high expressed P2X4R, when compared with the normal human astrocytes (NHA) cells. To gain the function of P2X4R, P2X4R silence cells were constructed by transfection with P2X4R small interfering RNA (siRNA). We found that P2X4R deletion impeded T98 and U87 cell viability and proliferation, and further studies indicated that cell apoptosis and caspase-3 activity was increased in T98 and U87 cell transfected with P2X4R siRNA. Subsequently, we confirmed that P2X4R silence suppressed brain-derived neurotrophic factor (BDNF), Trk receptor tyrosine kinases (TrkB), and activating transcription factor 4 (ATF4) expression in T98 and U87 cells. And P2X4R siRNA-induced ATF4-expression inhibition dependent on BDNF/TrkB signaling pathway. The impact of P2X4R silence on T98 and U87 cell growth and apoptosis was reversed by ATF4 overexpression. In summary, this study provides the first evidence that P2X4R plays important roles in GBM cell growth and apoptosis.

Involvement of vascular endothelial growth factor (VEGF) and mitogen-activated protein kinases (MAPK) in the mechanism of neuroleptic drugs

BACKGROUND

Recent evidence suggests that the mitogen activated protein kinase (MAPK)-associated signaling pathway in the frontal cortical areas demonstrates abnormal activity in cases of schizophrenia. Moreover, schizophrenia patients often display alterations in the regional cellular energy metabolism and blood flow of the brain; these are shown to parallel changes in angiogenesis primarily mediated by vascular endothelial growth factor (VEGF).

METHODS

The present study examines the differential effects of time-dependent treatment with haloperidol, olanzapine and amisulpride (20μM) on VEGF and MAPK mRNA expression and VEGF level, using the T98 cell line as an example of nerve cells. For the purposes of comparison, the effect of neuroprotective pituitary adenylate cyclase-activating polypeptide (PACAP) on the expression of VEGF mRNA and secretion were also evaluated in this cell model.

RESULTS

RT-PCR analysis revealed that all the tested neuroleptics increased VEGF mRNA expression after 72-h incubation; however, only haloperidol and olanzapine also increased the level of VEGF detected by ELISA, and they demonstrated significantly stronger effects than PACAP. Haloperidol and olanzapine, but not amisulpride, decreased MAPK14 mRNA expression in T98G cells after 72-h incubation.

CONCLUSION

The obtained results suggest that haloperidol and olanzapine can trigger the MAPK and VEGF signaling pathway, which may contribute to their neuroprotective mechanism of action.