Influence of nNav1.5 on MHC class I expression in breast cancer

Identification of a gene score related to antigen processing and presentation machinery for predicting prognosis in head and neck squamous cell carcinoma and its potential implications for immunotherapy

BACKGROUND

Despite its crucial role in immune surveillance and cell survival of tumors, the significance of MHC antigen processing and presentation machinery (APM) is still not fully understood in head and neck squamous cell carcinoma (HNSCC). We sought to develop an APM gene score (APMGS) to predict prognosis and reveal the molecular and immune traits of the APMGS-defined subgroups in HNSCC.

METHODS

Based on the APM-related genes acquired from 6 databases, 117 combined machine learning algorithms were applied to develop APMGS with The Cancer Genome Atlas (TCGA)-HNSCC database and validated with the Gene Expression Omnibus (GEO) dataset. Comprehensive analysis was performed to investigate the molecular and immune features of APMGS subgroups.

RESULTS

The APMGS constructed by StepCox [both] + Ridge method achieved the highest C-index and area under curve (AUC) at 3 years and were thus adopted as the final model. Low-APMGS patients exhibited superior overall survival compared with high-APMGS patients in both TCGA and GEO cohorts. Subsequent analysis confirmed that a low APMGS was associated with immune response-related pathways; low TP53 mutation rate and low tumor mutation burden (TMB); a less aggressive phenotype; high infiltration of activated CD4+ memory T cells, CD8+ T cells, follicular helper T cells, and Tregs; active immunity; and higher sensitivity to chemotherapeutic and targeted agents. In contrast, a high APMGS linked to proteasome and protein export pathways; high TP53 mutation rate and high TMB; a more aggressive phenotype; high infiltration of M0 macrophages and eosinophils; suppressed immunity; and lower sensitivity to chemotherapeutic and targeted agents.

CONCLUSIONS

Our findings suggest that APMGS has potential to predict the prognosis, and molecular and immune characteristics of HNSCC, and may also serve as an indicator for immunotherapy benefit.

nNav1.5 expression is associated with glutamate level in breast cancer cells

Background

Glutamate and voltage-gated sodium channels, both have been the target of intense investigation for its involvement in carcinogenesis and progression of malignant disease. Breast cancer with increased level of glutamate often metastasize to other organs (especially bone), whilst re-expression of ‘neonatal’ Nav1.5, nNav1.5 in breast cancer is known to promote cell invasion in vitro, metastasis in vivo and positive lymph node metastasis in patients.

Methods

In this study, the role of nNav1.5 in regulating glutamate level in human breast cancer cells was examined using pharmacological approach (VGSCs specific blocker, TTX, glutamate release inhibitor, riluzole and siRNA-nNav1.5). Effect of these agents were evaluated based on endogenous and exogenous glutamate concentration using glutamate fluorometric assay, mRNA expression of nNav1.5 using qPCR and finally, invasion using 3D culture assay.

Results

Endogenous and exogenous glutamate levels were significantly higher in aggressive human breast cancer cells, MDA-MB-231 cells compared to less aggressive human breast cancer cells, MCF-7 and non-cancerous human breast epithelial cells, MCF-10A. Treatment with TTX to MDA-MB-231 cells resulted in significant reduction of endogenous and exogenous glutamate levels corresponded with significant suppression of cell invasion. Subsequently, downregulation of nNav1.5 gene was observed in TTX-treated cells.

Conclusions

An interesting link between nNav1.5 expression and glutamate level in aggressive breast cancer cells was detected and requires further investigation.

Discovering the Triad between Nav1.5, Breast Cancer, and the Immune System: A Fundamental Review and Future Perspectives

Nav1.5 is one of the nine voltage-gated sodium channel-alpha subunit (VGSC-α) family members. The Nav1.5 channel typically carries an inward sodium ion current that depolarises the membrane potential during the upstroke of the cardiac action potential. The neonatal isoform of Nav1.5, nNav1.5, is produced via VGSC-α alternative splicing. nNav1.5 is known to potentiate breast cancer metastasis. Despite their well-known biological functions, the immunological perspectives of these channels are poorly explored. The current review has attempted to summarise the triad between Nav1.5 (nNav1.5), breast cancer, and the immune system. To date, there is no such review available that encompasses these three components as most reviews focus on the molecular and pharmacological prospects of Nav1.5. This review is divided into three major subsections: (1) the review highlights the roles of Nav1.5 and nNav1.5 in potentiating the progression of breast cancer, (2) focuses on the general connection between breast cancer and the immune system, and finally (3) the review emphasises the involvements of Nav1.5 and nNav1.5 in the functionality of the immune system and the immunogenicity. Compared to the other subsections, section three is pretty unexploited; it would be interesting to study this subsection as it completes the triad.

Brugada Syndrome: Warning of a Systemic Condition?

Brugada syndrome (BrS) is a hereditary disorder, characterized by a specific electrocardiogram pattern and highly related to an increased risk of sudden cardiac death. BrS has been associated with other cardiac and non-cardiac pathologies, probably because of protein expression shared by the heart and other tissue types. In fact, the most commonly found mutated gene in BrS, SCN5A, is expressed throughout nearly the entire body. Consistent with this, large meals and alcohol consumption can trigger arrhythmic events in patients with BrS, suggesting a role for organs involved in the digestive and metabolic pathways. Ajmaline, a drug used to diagnose BrS, can have side effects on non-cardiac tissues, such as the liver, further supporting the idea of a role for organs involved in the digestive and metabolic pathways in BrS. The BrS electrocardiogram (ECG) sign has been associated with neural, digestive, and metabolic pathways, and potential biomarkers for BrS have been found in the serum or plasma. Here, we review the known associations between BrS and various organ systems, and demonstrate support for the hypothesis that BrS is not only a cardiac disorder, but rather a systemic one that affects virtually the whole body. Any time that the BrS ECG sign is found, it should be considered not a single disease, but rather the final step in any number of pathways that ultimately threaten the patient's life. A multi-omics approach would be appropriate to study this syndrome, including genetics, epigenomics, transcriptomics, proteomics, metabolomics, lipidomics, and glycomics, resulting eventually in a biomarker for BrS and the ability to diagnose this syndrome using a minimally invasive blood test, avoiding the risk associated with ajmaline testing.