PANX2 and brain lower grade glioma genesis: A bioinformatic analysis

Ligand-Gated Ion Channels: Prognostic and Therapeutic Implications for Gliomas

Gliomas are common primary brain malignancies that remain difficult to treat due to their overall aggressiveness and heterogeneity. Although a variety of therapeutic strategies have been employed for the treatment of gliomas, there is increasing evidence that suggests ligand-gated ion channels (LGICs) can serve as a valuable biomarker and diagnostic tool in the pathogenesis of gliomas. Various LGICs, including P2X, SYT16, and PANX2, have the potential to become altered in the pathogenesis of glioma, which can disrupt the homeostatic activity of neurons, microglia, and astrocytes, further exacerbating the symptoms and progression of glioma. Consequently, LGICs, including purinoceptors, glutamate-gated receptors, and Cys-loop receptors, have been targeted in clinical trials for their potential therapeutic benefit in the diagnosis and treatment of gliomas. In this review, we discuss the role of LGICs in the pathogenesis of glioma, including genetic factors and the effect of altered LGIC activity on the biological functioning of neuronal cells. Additionally, we discuss current and emerging investigations regarding the use of LGICs as a clinical target and potential therapeutic for gliomas.

Rocuronium bromide suppresses esophageal cancer via blocking the secretion of C-X-C motif chemokine ligand 12 from cancer associated fibroblasts

BACKGROUND

Cancer associated fibroblasts (CAFs) communicate metabolically with tumor genesis and development. Rocuronium bromide (RB) is reported to exert certain inhibitory effect on tumor. Here, we investigate the role of RB in esophageal cancer (EC) malignant progression.

METHODS

Tumor xenograft models with EC cells were locally and systemically administrated with RB to detect the influence of different administrations on tumor progression. Mouse CAFs PDGFRα⁺/F4/80^- were sorted by Flow cytometry with specific antibodies. CAFs were treated with RB and co-cultured with EC cells. The proliferation, invasion and apoptosis assays of EC cells were performed to detect the influences of RB targeting CAFs on EC cell malignant progression. Human fibroblasts were employed to perform these detections to confirm RB indirect effect on EC cells. The gene expression changes of CAFs response to RB treatment were detected using RNA sequencing and verified by Western blot, immunohistochemistry and ELISA.

RESULTS

Tumors in xenograft mice were observed significantly inhibited by local RB administration, but not by systemic administration. Moreover EC cells did not show obvious change in viability when direct stimulated with RB in vitro. However, when CAFs treated with RB were co-cultured with EC cells, obvious suppressions were observed in EC cell malignancy, including proliferation, invasion and apoptosis. Human fibroblasts were employed to perform these assays and similar results were obtained. RNA sequencing data of human fibroblast treated with RB, and Western blot, immunohistochemistry and ELISA results all showed that CXCL12 expression was significantly diminished in vivo and in vitro by RB. EC cells direct treated with CXCL12 showed much higher malignancy. Moreover cell autophagy and PI3K/AKT/mTOR signaling pathway in CAFs were both suppressed by RB which can be reversed by Rapamycin pretreatment.

CONCLUSIONS

Our data suggest that RB could repress PI3K/AKT/mTOR signaling pathway and autophagy to block the CXCL12 expression in CAFs, thereby weakening the CXCL12-mediated EC tumor progression. Our data provide a novel insight into the underlying mechanism of RB inhibiting EC, and emphasize the importance of tumor microenvironment (cytokines from CAFs) in modulating cancer malignant progression.

Cryo-EM structure of human heptameric pannexin 2 channel

Pannexin 2 (Panx2) is a large-pore ATP-permeable channel with critical roles in various physiological processes, such as the inflammatory response, energy production and apoptosis. Its dysfunction is related to numerous pathological conditions including ischemic brain injury, glioma and glioblastoma multiforme. However, the working mechanism of Panx2 remains unclear. Here, we present the cryo-electron microscopy structure of human Panx2 at a resolution of 3.4 Å. Panx2 structure assembles as a heptamer, forming an exceptionally wide channel pore across the transmembrane and intracellular domains, which is compatible with ATP permeation. Comparing Panx2 with Panx1 structures in different states reveals that the Panx2 structure corresponds to an open channel state. A ring of seven arginine residues located at the extracellular entrance forms the narrowest site of the channel, which serves as the critical molecular filter controlling the permeation of substrate molecules. This is further verified by molecular dynamics simulations and ATP release assays. Our studies reveal the architecture of the Panx2 channel and provide insights into the molecular mechanism of its channel gating.

PriPath: identifying dysregulated pathways from differential gene expression via grouping, scoring, and modeling with an embedded feature selection approach

BACKGROUND

Cell homeostasis relies on the concerted actions of genes, and dysregulated genes can lead to diseases. In living organisms, genes or their products do not act alone but within networks. Subsets of these networks can be viewed as modules that provide specific functionality to an organism. The Kyoto encyclopedia of genes and genomes (KEGG) systematically analyzes gene functions, proteins, and molecules and combines them into pathways. Measurements of gene expression (e.g., RNA-seq data) can be mapped to KEGG pathways to determine which modules are affected or dysregulated in the disease. However, genes acting in multiple pathways and other inherent issues complicate such analyses. Many current approaches may only employ gene expression data and need to pay more attention to some of the existing knowledge stored in KEGG pathways for detecting dysregulated pathways. New methods that consider more precompiled information are required for a more holistic association between gene expression and diseases.

RESULTS

PriPath is a novel approach that transfers the generic process of grouping and scoring, followed by modeling to analyze gene expression with KEGG pathways. In PriPath, KEGG pathways are utilized as the grouping function as part of a machine learning algorithm for selecting the most significant KEGG pathways. A machine learning model is trained to differentiate between diseases and controls using those groups. We have tested PriPath on 13 gene expression datasets of various cancers and other diseases. Our proposed approach successfully assigned biologically and clinically relevant KEGG terms to the samples based on the differentially expressed genes. We have comparatively evaluated the performance of PriPath against other tools, which are similar in their merit. For each dataset, we manually confirmed the top results of PriPath in the literature and found that most predictions can be supported by previous experimental research.

CONCLUSIONS

PriPath can thus aid in determining dysregulated pathways, which applies to medical diagnostics. In the future, we aim to advance this approach so that it can perform patient stratification based on gene expression and identify druggable targets. Thereby, we cover two aspects of precision medicine.

Development and validation of a prognostic 9-gene signature for colorectal cancer

Introduction

Colorectal cancer (CRC) is one of the most prevalent cancers globally with a high mortality rate. Predicting prognosis using disease progression and cancer pathologic stage is insufficient, and a prognostic factor that can accurately evaluate patient prognosis needs to be developed. In this study, we aimed to infer a prognostic gene signature to identify a functional signature associated with the prognosis of CRC patients.

Methods

First, we used univariate Cox regression, least absolute shrinkage and selection operator (lasso) regression, and multivariate Cox regression analyses to screen genes significantly associated with CRC patient prognosis, from colorectal cancer RNA sequencing data in The Cancer Genome Atlas (TCGA) database. We then calculated the risk score (RS) for each patient based on the expression of the nine candidate genes and developed a prognostic signature.

Results

Based on the optimal cut-off on the receiver operating characteristic (ROC) curve, patients were separated into high- and low-risk groups, and the difference in overall survival between the two groups was examined. Patients in the low-risk group had a better overall survival rate than those in the high-risk group. The results were validated using the GSE72970, GSE39582, and GSE17536 Gene Expression Omnibus (GEO) datasets, and the same conclusions were reached. ROC curve test of the RS signature also indicated that it had excellent accuracy. The RS signature was then compared with traditional clinical factors as a prognostic indicator, and we discovered that the RS signature had superior predictive ability.

Conclusion

The RS signature developed in this study has excellent predictive power for the prognosis of patients with CRC and broad applicability as a prognostic indicator for patients.

Th1 immune maturation effects of

Nocardia rubra cell-wall skeleton (Nr-CWS) is reported as an external immunotherapeutic enhancer with the advantage of antitumor effect on human cancers. However, the immune regulatory role of Nr-CWS is not fully illustrated. We studied mouse CD4+ T lymphocytes isolated from mice spleen were induced by Nr-CWS and observed that the differentiation of Th1 CD4+ T cells and the cytokines of IL-2, TNF-α, IFN-γ were all enhanced by Nr-CWS. Furthermore, RNA sequencing was conducted to investigate the different mRNA profiling induced by Nr-CWS. We observed that paired box 8 (PAX8) was significantly up-regulated in Nr-CWS-treated Th1 cells compared to control. As a transcription factor, chromatin immunoprecipitation sequencing was carried out to study the genome-wide distribution of PAX8. Interestingly, we found that the binding domain of PAX8 was elevated by Nr-CWS, and the target genes associated with these binding sites showed a positive correlation between their transcription and PAX8 binding strength. Finally, we determined that Nr-CWS could enhance the activity of the PI3 K/Akt signaling pathway. Akt agonist could mimic the effect of Nr-CWS for PAX8 up-regulation, while Akt inhibitor compromised the expression of PAX8. Taken together, we determined a novel role of Nr-CWS in boosting the activity of Th1 maturation via the PI3 K/Akt/PAX8 axis.

Pannexin 2 is expressed in murine skin and promotes UVB-induced apoptosis of keratinocytes

Pannexins (PANX) are a family of three channel-forming membrane glycoproteins expressed in the skin. Previous studies have focused on the role of PANX1 and PANX3 in the regulation of cellular functions in skin cells while PANX2, the largest member of this protein family, has not been investigated. In the current study, we explored the temporal PANX2 expression in murine skin and found that one Panx2 splice variant (Panx2-202) tends to be more abundant at the protein level and is continuously expressed in developed skin. PANX2 was detected in the suprabasal layers of the mouse epidermis and up-regulated in an in vitro model of rat epidermal keratinocyte differentiation. Furthermore, we show that in apoptotic rat keratinocytes, upon UV light B (UVB)-induced caspase-3/7 activation, ectopically overexpressed PANX2 is cleaved in its C-terminal domain at the D416 residue without increasing the apoptotic rate measured by caspase-3/7 activation. Notably, CRISPR-Cas9 mediated genetic deletion of rat Panx2 delays but does not impair caspase-3/7 activation and cytotoxicity in UVB-irradiated keratinocytes. We propose that endogenous PANX2 expression in keratinocytes promotes cell death after UVB insult and may contribute to skin homeostasis.

Pannexin biology and emerging linkages to cancer

Pannexins are a family of glycoproteins that comprises three members, PANX1, PANX2, and PANX3. The widely expressed and interrogated PANX1 forms heptameric membrane channels that primarily serve to connect the cytoplasm to the extracellular milieu by being selectively permeable to small signaling molecules when activated. Apart from notable exceptions, PANX1 in many tumor cells appears to facilitate tumor growth and metastasis, suggesting that pannexin-blocking therapeutics may have utility in cancer. Attenuation of PANX1 function must also consider the fact that PANX1 is found in stromal cells of the tumor microenvironment (TME), including immune cells. This review highlights the key discoveries of the past 5 years that suggest pannexins facilitate, or in some cases inhibit, tumor cell growth and metastasis via direct protein interactions and through the regulated efflux of signaling molecules.