Role for calcium-activated potassium channels (BK) in migration control of human hepatocellular carcinoma cells

Metal Ion Signaling in Biomedicine

Complex multicellular organisms are composed of distinct tissues involving specialized cells that can perform specific functions, making such life forms possible. Species are defined by their genomes, and differences between individuals within a given species directly result from variations in their genetic codes. While genetic alterations can give rise to disease-causing acquisitions of distinct cell identities, it is now well-established that biochemical imbalances within a cell can also lead to cellular dysfunction and diseases. Specifically, nongenetic chemical events orchestrate cell metabolism and transcriptional programs that govern functional cell identity. Thus, imbalances in cell signaling, which broadly defines the conversion of extracellular signals into intracellular biochemical changes, can also contribute to the acquisition of diseased cell states. Metal ions exhibit unique chemical properties that can be exploited by the cell. For instance, metal ions maintain the ionic balance within the cell, coordinate amino acid residues or nucleobases altering folding and function of biomolecules, or directly catalyze specific chemical reactions. Thus, metals are essential cell signaling effectors in normal physiology and disease. Deciphering metal ion signaling is a challenging endeavor that can illuminate pathways to be targeted for therapeutic intervention. Here, we review key cellular processes where metal ions play essential roles and describe how targeting metal ion signaling pathways has been instrumental to dissecting the biochemistry of the cell and how this has led to the development of effective therapeutic strategies.

Functional expression of the proton sensors ASIC1a, TMEM206, and OGR1 together with BKCa channels is associated with cell volume changes and cell death under strongly acidic conditions in DAOY medulloblastoma cells

Fast growing solid tumors are frequently surrounded by an acidic microenvironment. Tumor cells employ a variety of mechanisms to survive and proliferate under these harsh conditions. In that regard, acid-sensitive membrane receptors constitute a particularly interesting target, since they can affect cellular functions through ion flow and second messenger cascades. Our knowledge of these processes remains sparse, however, especially regarding medulloblastoma, the most common pediatric CNS malignancy. In this study, using RT-qPCR, whole-cell patch clamp, and Ca2+-imaging, we uncovered several ion channels and a G protein-coupled receptor, which were regulated directly or indirectly by low extracellular pH in DAOY and UW228 medulloblastoma cells. Acidification directly activated acid-sensing ion channel 1a (ASIC1a), the proton-activated Cl- channel (PAC, ASOR, or TMEM206), and the proton-activated G protein-coupled receptor OGR1. The resulting Ca2+ signal secondarily activated the large conductance calcium-activated potassium channel (BKCa). Our analyses uncover a complex relationship of these transmembrane proteins in DAOY cells that resulted in cell volume changes and induced cell death under strongly acidic conditions. Collectively, our results suggest that these ion channels in concert with OGR1 may shape the growth and evolution of medulloblastoma cells in their acidic microenvironment.

Challenges in the Therapeutic Targeting of KCa Channels: From Basic Physiology to Clinical Applications

Calcium-activated potassium (KCa) channels are ubiquitously expressed throughout the body and are able to regulate membrane potential and intracellular calcium concentrations, thereby playing key roles in cellular physiology and signal transmission. Consequently, it is unsurprising that KCa channels have been implicated in various diseases, making them potential targets for pharmaceutical interventions. Over the past two decades, numerous studies have been conducted to develop KCa channel-targeting drugs, including those for disorders of the central and peripheral nervous, cardiovascular, and urinary systems and for cancer. In this review, we synthesize recent findings regarding the structure and activating mechanisms of KCa channels. We also discuss the role of KCa channel modulators in therapeutic medicine. Finally, we identify the major reasons behind the delay in bringing these modulators to the pharmaceutical market and propose new strategies to promote their application.

Enhancing Human Cutaneous Wound Healing through Targeted Suppression of Large Conductance Ca2+-Activated K+ Channels

The modulation of K+ channels plays a crucial role in cell migration and proliferation, but the effect of K+ channels on human cutaneous wound healing (CWH) remains underexplored. This study aimed to determine the necessity of modulating K+ channel activity and expression for human CWH. The use of 25 mM KCl as a K+ channel blocker markedly improved wound healing in vitro (in keratinocytes and fibroblasts) and in vivo (in rat and porcine models). K+ channel blockers, such as quinine and tetraethylammonium, aided in vitro wound healing, while Ba2+ was the exception and did not show similar effects. Single-channel recordings revealed that the Ba2+-insensitive large conductance Ca2+-activated K+ (BKCa) channel was predominantly present in human keratinocytes. NS1619, an opener of the BKCa channel, hindered wound healing processes like proliferation, migration, and filopodia formation. Conversely, charybdotoxin and iberiotoxin, which are BKCa channel blockers, dramatically enhanced these processes. The downregulation of BKCa also improved CWH, whereas its overexpression impeded these healing processes. These findings underscore the facilitative effect of BKCa channel suppression on CWH, proposing BKCa channels as potential molecular targets for enhancing human cutaneous wound healing.

Deciphering essential druggable genes reveals potential immune-inflammatory axis in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is a malignant tumor with a high mortality rate and poor prognosis in patients. Its pathogenesis is a complex process of multi-factors and multi-steps. However, the etiology and exact molecular mechanism are not completely clear.

METHODS

Here, we constructed a specific-expressed network based on RNA sequencing data. Gene and miRNA expression profiles and clinical evidence were integrated to detect hepatocellular carcinoma survival modules. Finally, we attempted to identify potential key biomarkers and drug targets by integrating drug sensitivity analysis and immune infiltration analysis.

RESULTS

A total of 42 prognostic modules for hepatocellular carcinoma were detected. The prognostic modules were significantly enriched with known cancer-related molecules and 12.93 % molecules of prognostic modules had been found were the targets of small molecule drug. In addition, we found that 38 of 42 (90.48 %) essential genes were associated with the proportions of at least one of the 7 immune cell types.

CONCLUSION

We integrated clinical prognosis information, RNA sequencing data, and drug activity data to explore risk modules of hepatocellular carcinoma. Through drug sensitivity analysis and immune infiltration analysis, we assessed the value of hub genes in the modules as potential biomarkers and drug targets for hepatocellular carcinoma. The protocol provides new insight into parsing the molecular mechanism and theoretical basis of hepatocellular carcinoma.

Potassium channels as novel molecular targets in hepatocellular carcinoma (Review)

Hepatocellular carcinoma (HCC) poses a serious health burden worldwide. It is often not diagnosed until the patient is at an advanced stage of the disease, when treatment options are limited and the prognosis is poor. Therefore, novel treatment strategies are urgently required. Potassium (K+) channels have an important role in HCC, including regulating the proliferation, migration, invasion and drug resistance of HCC cells. The aim of the present review was therefore to survey the relevant publications that have investigated K+ channels not only as markers for the early diagnosis of HCC, but also as potential therapeutic targets for the treatment of HCC. Several of these channels have been indicated to be the sites of action for natural products previously known to inhibit HCC; however, more systematic studies are required to determine which K+ channels may be utilized for the clinical treatment of HCC, particularly in the advanced stages of the disease and in cases where patients are resistant to the existing drugs.

Potassium channels, tumorigenesis and targeted drugs

Potassium channels play an important role in human physiological function. Recently, various molecular mechanisms have implicated abnormal functioning of potassium channels in the proliferation, migration, invasion, apoptosis, and cancer stem cell phenotype formation. Potassium channels also mediate the association of tumor cells with the tumor microenvironment. Meanwhile, potassium channels are important targets for cancer chemotherapy. A variety of drugs exert anti-cancer effects by modulating potassium channels in tumor cells. Therefore, there is a need to understand how potassium channels participate in tumor development and progression, which could reveal new, novel targets for cancer diagnosis and treatment. This review summarizes the roles of voltage-gated potassium channels, calcium-activated potassium channels, inwardly rectifying potassium channels, and two-pore domain potassium channels in tumorigenesis and the underlying mechanism of potassium channel-targeted drugs. Therefore, the study lays the foundation for rational and effective drug design and individualized clinical therapeutics.

Potassium channels: Novel targets for tumor diagnosis and chemoresistance

In recent years, the role of potassium channels in tumors has been intensively studied. Potassium channel proteins are widely involved in various physiological and pathological processes of cells. The expression and dysfunction of potassium channels are closely related to tumor progression. Potassium channel blockers or activators present antitumor effects by directly inhibiting tumor growth or enhancing the potency of classical antitumor agents in combination therapy. This article reviews the mechanisms by which potassium channels contribute to tumor development in various tumors in recent years, introduces the potential of potassium channels as diagnostic targets and therapeutic means for tumors, and provides further ideas for the proper individualized treatment of tumors.

The expression characteristics and clinical significance of ACP6, a potential target of nitidine chloride, in hepatocellular carcinoma

BACKGROUND

Acid phosphatase type 6 (ACP6) is a mitochondrial lipid phosphate phosphatase that played a role in regulating lipid metabolism and there is still blank in the clinico-pathological significance and functional roles of ACP6 in human cancers. No investigations have been conducted on ACP6 in hepatocellular carcinoma (HCC) up to date.

METHODS

Herein, we appraised the clinico-pathological significance of ACP6 in HCC via organizing expression profiles from globally multi-center microarrays and RNA-seq datasets. The molecular basis of ACP6 in HCC was explored through multidimensional analysis. We also carried out in vitro and in vivo experiment on nude mice to investigate the effect of knocking down ACP6 expression on biological functions of HCC cells, and to evaluate the expression variance of ACP6 in xenograft of HCC tissues before and after the treatment of NC.

RESULTS

ACP6 displayed significant overexpression in HCC samples (standard mean difference (SMD) = 0.69, 95% confidence interval (CI) = 0.56-0.83) and up-regulated ACP6 performed well in screening HCC samples from non-cancer liver samples. ACP6 expression was also remarkably correlated with clinical progression and worse overall survival of HCC patients. There were close links between ACP6 expression and immune cells including B cells, CD8 + T cells and naive CD4 + T cells. Co-expressed genes of ACP6 mainly participated in pathways including cytokine-cytokine receptor interaction, glucocorticoid receptor pathway and NABA proteoglycans. The proliferation and migration rate of HCC cells transfected with ACP6 siRNA was significantly suppressed compared with those transfected with negative control siRNA. ACP6 expression was significantly inhibited by nitidine chloride (NC) in xenograft HCC tissues.

CONCLUSIONS

ACP6 expression may serve as novel clinical biomarker indicating the clinical development of HCC and ACP6 might be potential target of anti-cancer effect by NC in HCC.

Nonsynonymous C1653T Mutation of Hepatitis B Virus X Gene Enhances Malignancy of Hepatocellular Carcinoma Cells

Purpose

Methods

Results

Conclusion

Role for calcium-activated potassium channels (BK) in migration control of human hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is a leading cause of cancer‐related death worldwide. Its high metastasis rate is significantly correlated with poor patient prognosis. Elucidating the molecular mechanism underlying HCC metastasis is essential for HCC treatment. Owing to their high conductance, large‐conductance calcium‐activated potassium channels (BK channels) play a critical role in the control of membrane potential and have repeatedly been proposed as potential targets for cancer therapy. Emerging evidence suggests that BK channels are involved in the progression of cancer malignancies. The present study investigated the role of BK channels in mediating the hypoxia‐stimulated migration of HCC cells both in vitro and in vivo in the absence and presence of various BK channels modulators. We found that BK channels were functionally expressed on the membranes of the SMMC‐7721 and Huh7 HCC cell lines. Furthermore, blockage or activation of BK channels on the surface of HCC cells correspondingly inhibited or promoted HCC cell proliferation, migration and invasion in hypoxia conditions, with altered expression and distribution of cell‐cell adhesion molecule E‐cadherin and typical marker of mesenchymal cells, Vimentin, but not N‐cadherin. Hypoxia conditions did not alter BK channels expression but increased its open probability. Moreover, BK channels blocker IbTX significantly inhibited HCC cell remote colonization in HCC cell xenografted mice. In conclusion, the results of this study suggest that blocking BK channels offers an attractive strategy for treating HCC.