Neonatal Nav1.5 Protein Expression in Human Colorectal Cancer: Immunohistochemical Characterization and Clinical Evaluation

Clinical relevance of macromolecular complexes involving integrins, potassium and sodium ion channels and the sodium/proton antiporter in human breast cancer

BACKGROUND

Mounting evidence underline the relevance of macromolecular complexes in cancer. Integrins frequently recruit ion channels and transporters within complexes which behave as signaling hubs. A complex composed by β1 integrin, hERG1 K+ channel, the neonatal form of the Na+ channel NaV 1.5 (nNaV1.5) and the Na+/H+ antiporter NHE1 (NHE1/hERG1/β1/nNaV1.5 complex) has been recently described to be expressed and regulate relevant cancer related behaviors in Breast Cancer (BCa) cells.

METHODS

We analyzed the expression and impact on outcome of the genes encoding the four proteins forming the NHE1/hERG1/β1/nNaV1.5 complex (SLC9A1, KCNH2, ITGB1 and SCN5A) in public datasets. The corresponding proteins were also evaluated by immunohistochemistry and their expression was correlated with clinic-pathological and molecular characteristics and patients' survival.

RESULTS

The expression of KCNH2 and SCN5A was significantly correlated in primary BCa as occurs in the heart, although with a broader distribution, forming a functional network which also included ITGB1 and SLC9A1. The co-expression proteins emerged from the immunohistochemistry analysis. Interestingly, hERG1, nNav1.5 and the hERG1/β1 integrin complex associated with several clinical features, including molecular subtype and hormone receptor status. Moreover, hERG1 and the combination of hERG1 and nNav1.5 had impact on prognosis, contributing to identifying a group of patients with worse prognosis.

CONCLUSIONS

hERG1 and nNav1.5 channels along with β1 integrins and the NHE1 antiporter are co-expressed in BCa both at gene and protein levels, assembling into a macromolecular complex. The NHE1/hERG1/β1/nNaV1.5 complex can be considered a novel biomarker and potential target for therapy for BCa patients.

Effects of NaV1.5 and Rac1 on the Epithelial-Mesenchymal Transition in Breast Cancer

Breast cancer is a disease that seriously endangers the health of women. However, it is difficult to treat due to the emergence of metastasis and drug resistance. Exploring the metastasis mechanism of breast cancer is helpful to aim for the appropriate target. The epithelial-mesenchymal transition (EMT) is an important mechanism of breast cancer metastasis. Sodium channel 1.5(NaV1.5) and the GTPase Rac1 are factors related to the degree of malignancy of breast tumors. The expression of NaV1.5 and the activation of Rac1 are both involved in EMT. In addition, NaV1.5 can change the plasma membrane potential (Vm) by promoting the inflow of Na+ to depolarize the cell membrane, induce the activation of Rac1 and produce a cascade of reactions that lead to EMT in breast cancer cells; this sequence of events further induces the movement, migration and invasion of tumor cells and affects the prognosis of breast cancer patients. In this paper, the roles of NaV1.5 and Rac1 in EMT-mediated breast cancer progression were reviewed.

Voltage-gated sodium channels in cancers

Voltage-gated sodium channels (VGSCs) initiate action potentials in electrically excitable cells and tissues. Surprisingly, some VGSC genes are aberrantly expressed in a variety of cancers, derived from "non-excitable" tissues that do not generate classic action potentials, showing potential as a promising pharmacological target for cancer. Most of the previous review articles on this topic are limited in scope, and largely unable to provide researchers with a comprehensive understanding of the role of VGSC in cancers. Here, we review the expression patterns of all nine VGSC α-subunit genes (SCN1A-11A) and their four regulatory β-subunit genes (SCN1B-4B). We reviewed data from the Cancer Genome Atlas (TCGA) database, complemented by an extensive search of the published papers. We summarized and reviewed previous independent studies and analyzed the VGSC genes in the TCGA database regarding the potential impact of VGSC on cancers. A comparison between evidence gathered from independent studies and data review was performed to scrutinize potential biases in prior research and provide insights into future research directions. The review supports the view that VGSCs play an important role in diagnostics as well as therapeutics of some cancer types, such as breast, colon, prostate, and lung cancer. This paper provides an overview of the current knowledge on voltage-gated sodium channels in cancer, as well as potential avenues for further research. While further research is required to fully understand the role of VGSCs in cancer, the potential of VGSCs for clinical diagnosis and treatment is promising.

Overexpression of SCN5A overcomes ABC transporter-mediated multidrug resistance in acute myeloid leukemia through promoting apoptosis

BACKGROUND

This study aimed to explore the effect and mechanism of SCN5A overcoming ATP-binding cassette (ABC) transporter-mediated multidrug resistance (MDR) in acute myeloid leukemia (AML) through promoting apoptosis.

RESEARCH DESIGN AND METHODS

The tissues derived from AML patients were divided into Sensitive group and Resistance group according to the presence of drug-resistance. Human AML cell line HL-60 and drug-resistant strain HL-60/ADR were divided into HL-60/ADR-vector group, HL-60/ADR-SCN5A group, HL-60-vector group and HL-60-SCN5A group. RT-qPCR was used to detect the mRNA expression level of SCN5A; MTT assay to assess the survival rate and proliferation level of cells; flow cytometry to determine the apoptosis level; and western blot to check the levels of SCN5A, P-glycoprotein (P-gp), MDR protein 1 (MRP1), MDR gene 1 (MDR1), breast cancer resistance protein (BCRP), Bcl-2-associated X protein (Bax), and B-cell lymphoma 2 (Bcl-2) proteins in cells.

RESULTS

SCN5A expressed lowly in drug-resistant AML tissues and cells. Up-regulation of SCN5A inhibited MDR in HL-60 cells, enhanced the chemosensitivity of HL-60/ADR, and increased the apoptosis levels of HL-60 and HL-60/ADR cells. However, over-expression of SCN5A inhibited the expression of MDR-related proteins.

CONCLUSIONS

SCN5A may overcome ABC transporter-mediated MDR in AML through enhancing the apoptosis and inhibiting the expression of MDR proteins.

Tetracaine downregulates matrix metalloproteinase activity and inhibits invasiveness of strongly metastatic MDA-MB-231 human breast cancer cells

Tetracaine, a long-acting amino ester-type local anesthetic, prevents the initiation and propagation of action potentials by reversibly blocking voltage-gated sodium channels (VGSCs). These channels, which are highly expressed in several carcinomas (e.g. breast, prostate, colon and lung cancers) have been implicated in promoting metastatic behaviours. Recent evidence suggests that local anesthetics can suppress cancer progression. In this paper, we aimed to explore whether tetracaine would reduce the invasive characteristics of breast cancer cells. In a comparative approach, we used two cell lines of contracting metastatic potential: MDA-MB-231 (strongly metastatic) and MCF-7 (weakly metastatic). Tetracaine (50 μM and 75 μM) did not affect the proliferation of both MDA-MB-231 and MCF-7 cells. Importantly, tetracaine suppressed the migratory, invasive, and adhesive capacities of MDA-MB-231 cells; there was no effect on the motility of MCF-7 cells. Tetracaine treatment also significantly decreased the expression and activity levels of MMP-2 and MMP-9, whilst increasing TIMP-2 expression in MDA-MB-231 cells. On the other hand, VGSC α/Nav1.5 and VGSC-β1 mRNA and protein expression levels were not affected. We conclude that tetracaine has anti-invasive effects on breast cancer cells and may be exploited clinically, for example, in surgery and/or in combination therapies.

From HDAC to Voltage-Gated Ion Channels: What's Next? The Long Road of Antiepileptic Drugs Repositioning in Cancer

Simple Summary

Although in the last decades the clinical outcome of cancer patients considerably improved, the major drawbacks still associated with chemotherapy are the unwanted side effects and the development of drug resistance. Therefore, a continuous effort in trying to discover new tumor markers, possibly of diagnostic, prognostic and therapeutic value, is being made. This review is aimed at highlighting the anti-tumor activity that several antiepileptic drugs (AEDs) exert in breast, prostate and other types of cancers, mainly focusing on their ability to block the voltage-gated Na⁺ and Ca⁺⁺ channels, as well as to inhibit the activity of histone deacetylases (HDACs), all well-documented tumor markers and/or molecular targets. The existence of additional AEDs molecular targets is highly suspected. Therefore, the repurposing of already available drugs as adjuvants in cancer treatment would have several advantages, such as reductions in dose-related toxicity CVs will be sent in a separate mail to the indicated address of combined treatments, lower production costs, and faster approval for clinical use.

Abstract

Cancer is a major health burden worldwide. Although the plethora of molecular targets identified in the last decades and the deriving developed treatments, which significantly improved patients’ outcome, the occurrence of resistance to therapies remains the major cause of relapse and mortality. Thus, efforts in identifying new markers to be exploited as molecular targets in cancer therapy are needed. This review will first give a glance on the diagnostic and therapeutic significance of histone deacetylase (HDAC) and voltage gated ion channels (VGICs) in cancer. Nevertheless, HDAC and VGICs have also been reported as molecular targets through which antiepileptic drugs (AEDs) seem to exert their anticancer activity. This should be claimed as a great advantage. Indeed, due to the slowness of drug approval procedures, the attempt to turn to off-label use of already approved medicines would be highly preferable. Therefore, an updated and accurate overview of both preclinical and clinical data of commonly prescribed AEDs (mainly valproic acid, lamotrigine, carbamazepine, phenytoin and gabapentin) in breast, prostate, brain and other cancers will follow. Finally, a glance at the emerging attempt to administer AEDs by means of opportunely designed drug delivery systems (DDSs), so to limit toxicity and improve bioavailability, is also given.

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.