The Kv10.1 Channel: A Promising Target in Cancer

Novel insights into voltage-gated ion channels: Translational breakthroughs in medical oncology

Preclinical evidence suggests that voltage gradients can act as a kind of top-down master regulator during embryogenesis and orchestrate downstream molecular-genetic pathways during organ regeneration or repair. Moreover, electrical stimulation shifts response to injury toward regeneration instead of healing or scarring. Cancer and embryogenesis not only share common phenotypical features but also commonly upregulated molecular pathways. Voltage-gated ion channel activity is directly or indirectly linked to the pathogenesis of cancer hallmarks, while experimental and clinical studies suggest that their modulation, e.g., by anesthetic agents, may exert antitumor effects. A large recent clinical trial served as a proof-of-principle for the benefit of preoperative use of topical sodium channel blockade as a potential anticancer strategy against early human breast cancers. Regardless of whether ion channel aberrations are primary or secondary cancer drivers, understanding the functional consequences of these events may guide us toward the development of novel therapeutic approaches.

Cell-Based Thallium-Influx Fluorescence Assay for Kv10.1 Channels

The development of cell-based fluorescent assays has resulted in an incredible tool for searching new ion channels' modulators with a biophysical and clinical profile. Among all the ion channels, potassium (K+)-permeable channels represent the most diverse and relevant for cell function, making them attractive targets for drug discovery. Some of the cell-based assays for K+ channels take advantage of a thallium-sensitive dye whose fluorescence increased upon the binding of thallium (Tl+), an ion able to move through K+ channels. We optimize the FLIPR Potassium Assay Kit based on thallium influx to measure the Kv10.1 activity.

SKCa- and Kv1-type potassium channels and cancer: Promising therapeutic targets?

Ion channels are transmembrane structures that allow the passage of ions across cell membranes such as the plasma membrane or the membranes of various organelles like the nucleus, endoplasmic reticulum, Golgi apparatus or mitochondria. Aberrant expression of various ion channels has been demonstrated in several tumor cells, leading to the promotion of key functions in tumor development, such as cell proliferation, resistance to apoptosis, angiogenesis, invasion and metastasis. The link between ion channels and these key biological functions that promote tumor development has led to the classification of cancers as oncochannelopathies. Among all ion channels, the most varied and numerous, forming the largest family, are the potassium channels, with over 70 genes encoding them in humans. In this context, this review will provide a non-exhaustive overview of the role of plasma membrane potassium channels in cancer, describing 1) the nomenclature and structure of potassium channels, 2) the role of these channels in the control of biological functions that promotes tumor development such as proliferation, migration and cell death, and 3) the role of two particular classes of potassium channels, the SKCa- and Kv1- type potassium channels in cancer progression.

Fluorescent membrane potential assay for drug screening on Kv10.1 channel: identification of BL-1249 as a channel activator

Resting membrane potential is a bioelectric property of all cells. Multiple players govern this property, the ion channels being the most important. Ion channel dysfunction can affect cells' resting membrane potential and could be associated with numerous diseases. Therefore, the drug discovery focus on ion channels has increased yearly. In addition to patch-clamp, cell-based fluorescent assays have shown a rapid and reliable method for searching new ion channel modulators. Here, we used a cell-based membrane potential assay to search for new blockers of the Kv10.1, a potassium channel strongly associated with cancer progression and a promising target in anticancer therapy. We found that fluoxetine and miconazole can inhibit the Kv10.1 channel in the micromolar range. In contrast, BL-1249 potentiates Kv10.1 currents in a dose-dependent manner, becoming the first molecule described as an activator of the channel. These results demonstrate that cell-based membrane potential assay can accelerate the discovery of new Kv10.1 modulators.

Nanoparticles-mediated ion channels manipulation: From their membrane interactions to bioapplications

Ion channels are transmembrane proteins ubiquitously expressed in all cells that control various ions (e.g. Na⁺, K⁺, Ca²⁺ and Cl^- etc) crossing cellular plasma membrane, which play critical roles in physiological processes including regulating signal transduction, cell proliferation as well as excitatory cell excitation and conduction. Abnormal ion channel function is usually associated with dysfunctions and many diseases, such as neurodegenerative disorders, ophthalmic diseases, pulmonary diseases and even cancers. The precise regulation of ion channels not only helps to decipher physiological and pathological processes, but also is expected to become cutting-edge means for disease treatment. Recently, nanoparticles-mediated ion channel manipulation emerges as a highly promising way to meet the increasing requirements with respect to their simple, efficient, precise, spatiotemporally controllable and non-invasive regulation in biomedicine and other research frontiers. Thanks the advantages of their unique properties, nanoparticles can not only directly block the pore sites or kinetics of ion channels through their tiny size effect, and perturb active voltage-gated ion channel by their charged surface, but they can also act as antennas to conduct or enhance external physical stimuli to achieve spatiotemporal, precise and efficient regulation of various ion channel activities (e.g. light-, mechanical-, and temperature-gated ion channels etc). So far, nanoparticles-mediated ion channel regulation has shown potential prospects in many biomedical fields at the interfaces of neuro- and cardiovascular modulation, physiological function regeneration and tumor therapy et al. Towards such important fields, in this typical review, we specifically outline the latest studies of different types of ion channels and their activities relevant to the diseases. In addition, the different types of stimulation responsive nanoparticles, their interaction modes and targeting strategies towards the plasma membrane ion channels will be systematically summarized. More importantly, the ion channel regulatory methods mediated by functional nanoparticles and their bioapplications associated with physiological modulation and therapeutic development will be discussed. Last but not least, current challenges and future perspectives in this field will be covered as well.

A Multidisciplinary Approach Establishes a Link between Transglutaminase 2 and the Kv10.1 Voltage-Dependent K+ Channel in Breast Cancer

Since the multifunctionality of transglutaminase 2 (TG2) includes extra- and intracellular functions, we investigated the effects of intracellular administration of TG2 inhibitors in three breast cancer cell lines, MDA-MB-231, MDA-MB-436 and MDA-MB-468, which are representative of different triple-negative phenotypes, using a patch-clamp technique. The first cell line has a highly voltage-dependent a membrane current, which is low in the second and almost absent in the third one. While applying a voltage protocol to responsive single cells, injection of TG2 inhibitors triggered a significant decrease of the current in MDA-MB-231 that we attributed to voltage-dependent K⁺ channels using the specific inhibitors 4-aminopyridine and astemizole. Since the Kv10.1 channel plays a dominant role as a marker of cell migration and survival in breast cancer, we investigated its relationship with TG2 by immunoprecipitation. Our data reveal their physical interaction affects membrane currents in MDA-MB-231 but not in the less sensitive MDA-MB-436 cells. We further correlated the efficacy of TG2 inhibition with metabolic changes in the supernatants of treated cells, resulting in increased concentration of methyl- and dimethylamines, representing possible response markers. In conclusion, our findings highlight the interference of TG2 inhibitors with the Kv10.1 channel as a potential therapeutic tool depending on the specific features of cancer cells.

Potassium Ion Channels in Malignant Central Nervous System Cancers

Malignant central nervous system (CNS) cancers are among the most difficult to treat, with low rates of survival and a high likelihood of recurrence. This is primarily due to their location within the CNS, hindering adequate drug delivery and tumour access via surgery. Furthermore, CNS cancer cells are highly plastic, an adaptive property that enables them to bypass targeted treatment strategies and develop drug resistance. Potassium ion channels have long been implicated in the progression of many cancers due to their integral role in several hallmarks of the disease. Here, we will explore this relationship further, with a focus on malignant CNS cancers, including high-grade glioma (HGG). HGG is the most lethal form of primary brain tumour in adults, with the majority of patient mortality attributed to drug-resistant secondary tumours. Hence, targeting proteins that are integral to cellular plasticity could reduce tumour recurrence, improving survival. This review summarises the role of potassium ion channels in malignant CNS cancers, specifically how they contribute to proliferation, invasion, metastasis, angiogenesis, and plasticity. We will also explore how specific modulation of these proteins may provide a novel way to overcome drug resistance and improve patient outcomes.