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

Copper metabolism-related risk score identifies hepatocellular carcinoma subtypes and SLC27A5 as a potential regulator of cuproptosis

AIMS

Dysregulated copper metabolism has been noticed in many types of cancer including hepatocellular carcinoma (HCC); however, a comprehensive understanding about this dysregulation still remains unclear in HCC.

METHODS

A set of bioinformatic tools was integrated to analyze the expression and prognostic significance of copper metabolism-related genes. A related risk score, termed as CMscore, was developed via univariate Cox regression, least absolute shrinkage and selection operator (LASSO) Cox regression and multivariate Cox regression. Pathway enrichment analyses and tumor immune cell infiltration were further investigated in CMscore stratified HCC patients. Weighted correlation network analysis (WGCNA) was used to identify potential regulator of cuproptosis.

RESULTS

Copper metabolism was dysregulated in HCC. HCC patients in the high-CMscore group showed a significantly lower overall survival (OS) and enriched in most cancer-related pathways. Besides, HCC patients with high CMscore had higher expression of pro-tumor immune infiltrates and immune checkpoints. Moreover, cancer patients with high CMscore from two large cohorts exhibited significantly prolonged survival time after immunotherapy. WGCNA and subsequently correlation analysis revealed that SLC27A5 might be a potential regulator of cuproptosis in HCC. In vitro experiments revealed that SLC27A5 inhibited cell proliferation and migration of HCC cells and could upregulate FDX1, the key regulator of cuproptosis.

SIGNIFICANCE

The CMscore is helpful in clustering HCC patients with distinct prognosis, gene mutation signatures, and sensitivity to immunotherapy. SLC27A5 might serve as a potential target in the induction of cuproptosis in HCC.

Purine and purinergic receptors in health and disease

Purines and purinergic receptors are widely distributed throughout the human body. Purine molecules within cells play crucial roles in regulating energy metabolism and other cellular processes, while extracellular purines transmit signals through specific purinergic receptors. The ubiquitous purinergic signaling maintains normal neural excitability, digestion and absorption, respiratory movement, and other complex physiological activities, and participates in cell proliferation, differentiation, migration, and death. Pathological dysregulation of purinergic signaling can result in the development of various diseases, including neurodegeneration, inflammatory reactions, and malignant tumors. The dysregulation or dysfunction of purines and purinergic receptors has been demonstrated to be closely associated with tumor progression. Compared with other subtypes of purinergic receptors, the P2X7 receptor (P2X7R) exhibits distinct characteristics (i.e., a low affinity for ATP, dual functionality upon activation, the mediation of ion channels, and nonselective pores formation) and is considered a promising target for antitumor therapy, particularly in patients with poor response to immunotherapy This review summarizes the physiological and pathological significance of purinergic signaling and purinergic receptors, analyzes their complex relationship with tumors, and proposes potential antitumor immunotherapy strategies from tumor P2X7R inhibition, tumor P2X7R overactivation, and host P2X7R activation. This review provides a reference for clinical immunotherapy and mechanism investigation.

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.

Insight into the transcription factors regulating Ischemic Stroke and Glioma in Response to Shared Stimuli

Cerebral ischemic stroke and glioma are the two leading causes of patient mortality globally. Despite physiological variations, 1 in 10 people who have an ischemic stroke go on to develop brain cancer, most notably gliomas. In addition, glioma treatments have also been shown to increase the risk of ischemic strokes. Stroke occurs more frequently in cancer patients than in the general population, according to traditional literature. Unbelievably, these events share multiple pathways, but the precise mechanism underlying their co-occurrence remains unknown. Transcription factors (TFs), the main components of gene expression programmes, finally determine the fate of cells and homeostasis. Both ischemic stroke and glioma exhibit aberrant expression of a large number of TFs, which are strongly linked to the pathophysiology and progression of both diseases. The precise genomic binding locations of TFs and how TF binding ultimately relates to transcriptional regulation remain elusive despite a strong interest in understanding how TFs regulate gene expression in both stroke and glioma. As a result, the importance of continuing efforts to understand TF-mediated gene regulation is highlighted in this review, along with some of the primary shared events in stroke and glioma.

Sevoflurane Induces Ferroptosis of Glioma Cells Through Activating the ATF4-CHAC1 Pathway

Objective

To clarify the function and mechanisms of sevoflurane (Sev) on ferroptosis in glioma cells.

Methods

Different concentrations of Sev were used to treat glioma cells U87 and U251. Ferroptosis inducer Erastin was used to incubate glioma cells combined with Sev and ATF4 siRNA transfection treatment. CCK-8 assay and colorimetric assay were performed to analyze cell viability and Fe+ concentration, respectively. The releases of reactive oxygen species (ROS) were determined by flow cytometry analysis. Transcriptional sequencing was used to screen the differential genes affected by Sev in U251 cells. The mRNA and protein expression of ferroptosis-associated genes was detected by qRT-PCR and Western blotting.

Results

Sev could suppress cell viability, increase ROS levels and Fe+ concentration, downregulate the protein expression levels of GPX4, and upregulate transferrin, ferritin, and Beclin-1 in a dose-dependent manner in U87 and U251 cells. The expression of ferroptosis and mitophagy-related gene activating transcription factor 4 (ATF4) was identified to be enhanced by Sev analyzed by transcriptional sequencing. ChaC glutathione-specific gamma-glutamylcyclotransferase 1 (CHAC1), which is involved in ferroptosis, is a downstream gene of ATF4. Inhibition of ATF4 could interrupt the expression of CHAC1 induced by Sev in U87 and U251 cells. Ferroptosis inducer Erastin treatment obviously inhibited the cell viability, elevated the Fe2+ concentration, and promoted ROS generation in U87 and U251 cells. The protein level of ATF4 and CHAC1 was increased in Erastin-treated U87 and U251 cells. Moreover, the interruption of Sev-induced ferroptosis and CHAC1 activating induced by ATF4 suppression could be reversed by Erastin.

Conclusions

In summary, this study suggested that Sev exposure-induced ferroptosis by the ATF4-CHAC1 pathway in glioma cells.

Ligand-Gated Ion Channels as Targets for Treatment and Management of Cancers

Ligand-gated ion channels are an ionotropic receptor subtype characterized by the binding of an extracellular ligand, followed by the transient passage of ions through a transmembrane pore. Ligand-gated ion channels are commonly subcategorized into three superfamilies: purinoreceptors, glutamate receptors, and Cys-loop receptors. This classification is based on the differing topographical morphology of the receptors, which in turn confers functional differences. Ligand-gated ion channels have a diverse spatial and temporal expression which implicate them in key cellular processes. Given that the transcellular electrochemical gradient is finely tuned in eukaryotic cells, any disruption in this homeostasis can contribute to aberrancies, including altering the activity of pro-tumorigenic molecular pathways, such as the MAPK/ERK, RAS, and mTOR pathways. Ligand-gated ion channels therefore serve as a potential targetable system for cancer therapeutics. In this review, we analyze the role that each of the three ligand-gated ion channel superfamilies has concerning tumor proliferation and as a target for the treatment of cancer symptomatology.

Function of the P2X7 receptor in hematopoiesis and leukemogenesis

Adenosine triphosphate (ATP) accumulates at tissue injury and inflammation sites. The P2X7 receptor is an ATP-gated ion channel known for its cytotoxic activity. However, P2X7 receptors also play important roles in the growth of cancer and the immune regulation. Functional P2X7 receptor is widely expressed in murine and human hematopoietic stem cells and their lineages, including monocytes, macrophages, mast cells, and B or T lymphocytes, and participates in various physiological and pathologic activities. Therefore, it is not surprising that the P2X7 receptor is important for the normal hematopoiesis and leukemogenesis. Here, we summarize the biological functions of P2X7 receptor during both normal hematopoiesis and leukemogenesis. In particular, we found that ATP levels are dramatically increased in the leukemic bone marrow niche and the fates of leukemia-initiating cells of acute myeloid leukemia are tightly controlled by P2X7 expression and ATP-P2X7-mediated signaling pathways. These findings strongly indicate that the P2X7 receptor may be considered a potential biomarker of hematological malignancies in bone marrow niches, and its antagonists may be useful for the leukemia treatment in addition to the traditional chemotherapy.

Bone marrow niche ATP levels determine leukemia-initiating cell activity via P2X7 in leukemic models

How particular bone marrow niche factors contribute to the leukemogenic activities of leukemia-initiating cells (LICs) remains largely unknown. Here, we showed that ATP levels were markedly increased in the bone marrow niches of mice with acute myeloid leukemia (AML), and LICs preferentially localized to the endosteal niche with relatively high ATP levels, as indicated by a sensitive ATP indicator. ATP could efficiently induce the influx of ions into LICs in an MLL-AF9-induced murine AML model via the ligand-gated ion channel P2X7. P2x7 deletion led to notably impaired homing and self-renewal capacities of LICs and contributed to an approximately 5-fold decrease in the number of functional LICs but had no effect on normal hematopoiesis. ATP/P2X7 signaling enhanced the calcium flux-mediated phosphorylation of CREB, which further transactivated phosphoglycerate dehydrogenase (Phgdh) expression to maintain serine metabolism and LIC fates. P2X7 knockdown resulted in a markedly extended survival of recipients transplanted with either human AML cell lines or primary leukemia cells. Blockade of ATP/P2X7 signaling could efficiently inhibit leukemogenesis. Here, we provide a perspective for understanding how ATP/P2X7 signaling sustains LIC activities, which may benefit the development of specific strategies for targeting LICs or other types of cancer stem cells.

Identification of robust diagnostic and prognostic gene signatures in different grades of gliomas: a retrospective study

Background

Gliomas are the most common primary tumors of the central nervous system. The complexity and heterogeneity of the tumor makes it difficult to obtain good biomarkers for drug development. In this study, through The Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas (CGGA), we analyze the common diagnostic and prognostic moleculer markers in Caucasian and Asian populations, which can be used as drug targets in the future.

Methods

The RNA-seq data from Genotype-Tissue Expression (GTEx) and The Cancer Genome Atlas (TCGA) were analyzed to identify signatures. Based on the signatures, the prognosis index (PI) of every patient was constructed to predict the prognostic risk. Also, gene ontology (GO) functional enrichment analysis and KEGG analysis were conducted to investigate the biological functions of these mRNAs. Glioma patients’ data in the CGGA database were introduced to validate the effectiveness of the signatures among Chinese populations. Excluding the previously reported prognostic markers of gliomas from this study, the expression of HSPA5 and MTPN were examined by qRT-PCR and immunohistochemical assay.

Results

In total, 20 mRNAs were finally selected to build PI for patients from TCGA, including 16 high-risk genes and four low-risk genes. For Chinese patients, the log-rank test p values of PI were both less than 0.0001 in two independent datasets. And the AUCs were 0.831 and 0.907 for 3 years of two datasets, respectively. Moreover, among these 20 mRNAs, 10 and 15 mRNAs also had a significant predictive effect via univariate COX analysis in CGGA_693 and CGGA_325, respectively. qRT-PCR and Immunohistochemistry assay indicated that HSPA5 and MTPN over-expressed in Glioma samples compared to normal samples.

Conclusion

The 20-gene signature can forecast the risk of Glioma in TCGA effectively, moreover it can also predict the risks of Chinese patients through validation in the CGGA database. HSPA5 and MTPN are possible biomarkers of gliomas suitable for all populations to improve the prognosis of these patients.

P2X receptors in cancer growth and progression

It is increasingly appreciated that ion channels have a crucial role in tumors, either as promoters of cancer cell growth, or modulators of immune cell functions, or both. Among ion channels, P2X receptors have a special status because they are gated by ATP, a common and abundant component of the tumor microenvironment. Furthermore, one P2X receptor, i.e. P2X7, may also function as a conduit for ATP release, thus fuelling the increased extracellular ATP level in the tumor interstitium. These findings show that P2X receptors and extracellular ATP are indissoluble partners and key regulators of tumor growth, and suggest the exploitation of the extracellular ATP-P2X partnership to develop innovative therapeutic approaches to cancer.

Inhibiting the P2X4 Receptor Suppresses Prostate Cancer Growth In Vitro and In Vivo, Suggesting a Potential Clinical Target

Prostate cancer (PCa) is the most frequently diagnosed cancer in men, causing considerable morbidity and mortality. The P2X4 receptor (P2X4R) is the most ubiquitously expressed P2X receptor in mammals and is positively associated with tumorigenesis in many cancer types. However, its involvement in PCa progression is less understood. We hypothesized that P2X4R activity enhanced tumour formation by PCa cells. We showed that P2X4R was the most highly expressed, functional P2 receptor in these cells using quantitative reverse transcription PCR (RT-PCR) and a calcium influx assay. The effect of inhibiting P2X4R on PCa (PC3 and C4-2B4 cells) viability, proliferation, migration, invasion, and apoptosis were examined using the selective P2XR4 antagonists 5-BDBD and PSB-12062. The results demonstrated that inhibiting P2X4R impaired the growth and mobility of PCa cells but not apoptosis. In BALB/c immunocompromised nude mice inoculated with human PC3 cells subcutaneously, 5-BDBD showed anti-tumourigenic effects. Finally, a retrospective analysis of P2RX4 expression in clinical datasets (GDS1439, GDS1746, and GDS3289) suggested that P2X4R was positively associated with PCa malignancy. These studies suggest that P2X4R has a role in enhancing PCa tumour formation and is a clinically targetable candidate for which inhibitors are already available and have the potential to suppress disease progression.

Ion Channels as Therapeutic Targets in High Grade Gliomas

Simple Summary

Glioblastoma multiforme is an aggressive grade IV lethal brain tumour with a median survival of 14 months. Despite surgery to remove the tumour, and subsequent concurrent chemotherapy and radiotherapy, there is little in terms of effective treatment options. Because of this, exploring new treatment avenues is vital. Brain tumours are intrinsically electrically active; expressing unique patterns of ion channels, and this is a characteristic we can exploit. Ion channels are specialised proteins in the cell’s membrane that allow for the passage of positive and negatively charged ions in and out of the cell, controlling membrane potential. Membrane potential is a crucial biophysical signal in normal and cancerous cells. Research has identified that specific classes of ion channels not only move the cell through its cell cycle, thus encouraging growth and proliferation, but may also be essential in the development of brain tumours. Inhibition of sodium, potassium, calcium, and chloride channels has been shown to reduce the capacity of glioblastoma cells to grow and invade. Therefore, we propose that targeting ion channels and repurposing commercially available ion channel inhibitors may hold the key to new therapeutic avenues in high grade gliomas.

Abstract

Glioblastoma multiforme (GBM) is a lethal brain cancer with an average survival of 14–15 months even with exhaustive treatment. High grade gliomas (HGG) represent the leading cause of CNS cancer-related death in children and adults due to the aggressive nature of the tumour and limited treatment options. The scarcity of treatment available for GBM has opened the field to new modalities such as electrotherapy. Previous studies have identified the clinical benefit of electrotherapy in combination with chemotherapeutics, however the mechanistic action is unclear. Increasing evidence indicates that not only are ion channels key in regulating electrical signaling and membrane potential of excitable cells, they perform a crucial role in the development and neoplastic progression of brain tumours. Unlike other tissue types, neural tissue is intrinsically electrically active and reliant on ion channels and their function. Ion channels are essential in cell cycle control, invasion and migration of cancer cells and therefore present as valuable therapeutic targets. This review aims to discuss the role that ion channels hold in gliomagenesis and whether we can target and exploit these channels to provide new therapeutic targets and whether ion channels hold the mechanistic key to the newfound success of electrotherapies.