Anti-proliferative effect of Kv1.3 blockers in A549 human lung adenocarcinoma in vitro and in vivo

Harnessing the potency of scorpion venom-derived proteins: applications in cancer therapy

Despite breakthroughs in the development of cancer diagnosis and therapy, most current therapeutic approaches lack precise specificity and sensitivity, resulting in damage to healthy cells. Selective delivery of anti-cancer agents is thus an important goal of cancer therapy. Scorpion venom (SV) and/or body parts have been used since early civilizations for medicinal purposes, and in cultures, SV is still applied to the treatment of several diseases including cancer. SV contains numerous active micro and macromolecules with diverse pharmacological effects. These include potent anti-microbial, anti-viral, anti-inflammatory, and anti-cancer properties. This review focuses on the recent advances of SV-derived peptides as promising anti-cancer agents and their diagnostic and therapeutic potential applications in cancers such as glioma, breast cancer, prostate cancer, and colon cancer. Well-characterized SV-derived peptides are thus needed to serve as potent and selective adjuvant therapy for cancer, to significantly enhance the patients' survival and wellbeing.

Bioelectric pharmacology of cancer: A systematic review of ion channel drugs affecting the cancer phenotype

Cancer is a pernicious and pressing medical problem; moreover, it is a failure of multicellular morphogenesis that sheds much light on evolutionary developmental biology. Numerous classes of pharmacological agents have been considered as cancer therapeutics and evaluated as potential carcinogenic agents; however, these are spread throughout the primary literature. Here, we briefly review recent work on ion channel drugs as promising anti-cancer treatments and present a systematic review of the known cancer-relevant effects of 109 drugs targeting ion channels. The roles of ion channels in cancer are consistent with the importance of bioelectrical parameters in cell regulation and with the functions of bioelectric signaling in morphogenetic signals that act as cancer suppressors. We find that compounds that are well-known for having targets in the nervous system, such as voltage-gated ion channels, ligand-gated ion channels, proton pumps, and gap junctions are especially relevant to cancer. Our review suggests further opportunities for the repurposing of numerous promising candidates in the field of cancer electroceuticals.

Voltage-gated potassium channel 1.3: A promising molecular target in multiple disease therapy

Voltage-gated potassium channel 1.3 (Kv1.3) has emerged as a pivotal player in numerous biological processes and pathological conditions, sparking considerable interest as a potential therapeutic target across various diseases. In this review, we present a comprehensive examination of Kv1.3 channels, highlighting their fundamental characteristics and recent advancements in utilizing Kv1.3 inhibitors for treating autoimmune disorders, neuroinflammation, and cancers. Notably, Kv1.3 is prominently expressed in immune cells and implicated in immune responses and inflammation associated with autoimmune diseases and chronic inflammatory conditions. Moreover, its aberrant expression in certain tumors underscores its role in cancer progression. While preclinical studies have demonstrated the efficacy of Kv1.3 inhibitors, their clinical translation remains pending. Molecular imaging techniques offer promising avenues for tracking Kv1.3 inhibitors and assessing their therapeutic efficacy, thereby facilitating their development and clinical application. Challenges and future directions in Kv1.3 inhibitor research are also discussed, emphasizing the significant potential of targeting Kv1.3 as a promising therapeutic strategy across a spectrum of diseases.

Phytochemical Modulation of Ion Channels in Oncologic Symptomatology and Treatment

Modern chemotherapies offer a broad approach to cancer treatment but eliminate both cancer and non-cancer cells indiscriminately and, thus, are associated with a host of side effects. Advances in precision oncology have brought about new targeted therapeutics, albeit mostly limited to a subset of patients with an actionable mutation. They too come with side effects and, ultimately, 'self-resistance' to the treatment. There is recent interest in the modulation of ion channels, transmembrane proteins that regulate the flow of electrically charged molecules in and out of cells, as an approach to aid treatment of cancer. Phytochemicals have been shown to act on ion channels with high specificity regardless of the tumor's genetic profile. This paper explores the use of phytochemicals in cancer symptom management and treatment.

Bioactive peptides: an alternative therapeutic approach for cancer management

Cancer is still considered a lethal disease worldwide and the patients' quality of life is affected by major side effects of the treatments including post-surgery complications, chemo-, and radiation therapy. Recently, new therapeutic approaches were considered globally for increasing conventional cancer therapy efficacy and decreasing the adverse effects. Bioactive peptides obtained from plant and animal sources have drawn increased attention because of their potential as complementary therapy. This review presents a contemporary examination of bioactive peptides derived from natural origins with demonstrated anticancer, ant invasion, and immunomodulation properties. For example, peptides derived from common beans, chickpeas, wheat germ, and mung beans exhibited antiproliferative and toxic effects on cancer cells, favoring cell cycle arrest and apoptosis. On the other hand, peptides from marine sources showed the potential for inhibiting tumor growth and metastasis. In this review we will discuss these data highlighting the potential befits of these approaches and the need of further investigations to fully characterize their potential in clinics.

Nanotechnology and Cancer Bioelectricity: Bridging the Gap Between Biology and Translational Medicine

Bioelectricity is the electrical activity that occurs within living cells and tissues. This activity is critical for regulating homeostatic cellular function and communication, and disruptions of the same can lead to a variety of conditions, including cancer. Cancer cells are known to exhibit abnormal electrical properties compared to their healthy counterparts, and this has driven researchers to investigate the potential of harnessing bioelectricity as a tool in cancer diagnosis, prognosis, and treatment. In parallel, bioelectricity represents one of the means to gain fundamental insights on how electrical signals and charges play a role in cancer insurgence, growth, and progression. This review provides a comprehensive analysis of the literature in this field, addressing the fundamentals of bioelectricity in single cancer cells, cancer cell cohorts, and cancerous tissues. The emerging role of bioelectricity in cancer proliferation and metastasis is introduced. Based on the acknowledgement that this biological information is still hard to access due to the existing gap between biological findings and translational medicine, the latest advancements in the field of nanotechnologies for cellular electrophysiology are examined, as well as the most recent developments in micro- and nano-devices for cancer diagnostics and therapy targeting bioelectricity.

Scorpion venom peptides: Molecular diversity, structural characteristics, and therapeutic use from channelopathies to viral infections and cancers

Animal venom is an important evolutionary innovation in nature. As one of the most representative animal venoms, scorpion venom contains an extremely diverse set of bioactive peptides. Scorpion venom peptides not only are 'poisons' that immobilize, paralyze, kill, or dissolve preys but also become important candidates for drug development and design. Here, the review focuses on the molecular diversity of scorpion venom peptides, their typical structural characteristics, and their multiple therapeutic or pharmaceutical applications in channelopathies, viral infections and cancers. Especially, the group of scorpion toxin TRPTx targeting transient receptor potential (TRP) channels is systematically summarized and worthy of attention because TRP channels play a crucial role in the regulation of homeostasis and the occurrence of diseases in human. We also further establish the potential relationship between the molecular characteristics and functional applications of scorpion venom peptides to provide a research basis for modern drug development and clinical utilization of scorpion venom resources.

Ion channels in lung cancer: biological and clinical relevance

Despite improvements in treatment, lung cancer is still a major health problem worldwide. Among lung cancer subtypes, the most frequent is represented by adenocarcinoma (belonging to the Non-Small Cell Lung Cancer class) although the most challenging and harder to treat is represented by Small Cell Lung Cancer, that occurs at lower frequency but has the worst prognosis. For these reasons, the standard of care for these patients is represented by a combination of surgery, radiation therapy and chemotherapy. In this view, searching for novel biomarkers that might help both in diagnosis and therapy is mandatory. In the last 30 years it was demonstrated that different families of ion channels are overexpressed in both lung cancer cell lines and primary tumours. The altered ion channel profile may be advantageous for diagnostic and therapeutic purposes since most of them are localised on the plasma membrane thus their detection is quite easy, as well as their block with specific drugs and antibodies. This review focuses on ion channels (Potassium, Sodium, Calcium, Chloride, Anion and Nicotinic Acetylcholine receptors) in lung cancer (both Non-Small Cell Lung Cancer and Small Cell Lung Cancer) and recapitulate the up-to-date knowledge about their role and clinical relevance for a potential use in the clinical setting, for lung cancer diagnosis and therapy.

Design of ion channel blocking, toxin-like Kunitz inhibitor peptides from the tapeworm, Echinococcus granulosus, with potential anti-cancer activity

Over-expression of K+ channels has been reported in human cancers and is associated with the poor prognosis of several malignancies. EAG1, a particular potassium ion channel, is widely expressed in the brain but poorly expressed in other normal tissues. Kunitz proteins are dominant in metazoan including the dog tapeworm, Echinococcus granulosus. Using computational analyses on one A-type potassium channel, EAG1, and in vitro cellular methods, including major cancer cell biomarkers expression, immunocytochemistry and whole-cell patch clamp, we demonstrated the anti-tumor activity of three synthetic small peptides derived from E. granulosus Kunitz4 protease inhibitors. Experiments showed induced significant apoptosis and inhibition of proliferation in both cancer cell lines via disruption in cell-cycle transition from the G0/G1 to S phase. Western blotting showed that the levels of cell cycle-related proteins including P27 and P53 were altered upon kunitz4-a and kunitz4-c treatment. Patch clamp analysis demonstrated a significant increase in spontaneous firing frequency in Purkinje neurons, and exposure to kunitz4-c was associated with an increase in the number of rebound action potentials after hyperpolarized current. This noteworthy component in nature could act as an ion channel blocker and is a potential candidate for cancer chemotherapy based on potassium channel blockage.

The Potent Antitumor Activity of Smp43 against Non-Small-Cell Lung Cancer A549 Cells via Inducing Membranolysis and Mitochondrial Dysfunction

Research has been conducted to investigate the potential application of scorpion venom-derived peptides in cancer therapy. Smp43, a cationic antimicrobial peptide from Scorpio maurus palmatus venom, has been found to exhibit suppressive activity against the proliferation of multiple cancer cell lines. However, its impact on non-small-cell lung cancer (NSCLC) cell lines has not been previously investigated. This study aimed to determine the cytotoxicity of Smp43 towards various NSCLC cell lines, particularly A549 cells with an IC₅₀ value of 2.58 μM. The results indicated that Smp43 was internalized into A549 cells through membranolysis and endocytosis, which caused cytoskeleton disorganization, a loss of mitochondrial membrane potential, an accumulation of reactive oxygen species (ROS), and abnormal apoptosis, cell cycle distribution, and autophagy due to mitochondrial dysfunction. Additionally, the study explored the in vivo protective effect of Smp43 in xenograft mice. The findings suggest that Smp43 has potential anticarcinoma properties exerted via the inducement of cellular processes related to cell membrane disruption and mitochondrial dysfunction.

Peptides with Diverse Functions from Scorpion Venom: A Great Opportunity for the Treatment of a Wide Variety of Diseases

Toxicology Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran

The venom glands are a rich source of biologically important peptides with pharmaceutical properties. Scorpion venoms have been identified as a reservoir for components that might be considered as great candidates for drug development. Pharmacological properties of the venom compounds have been confirmed in the treatment of different disorders. Ion channel blockers and AMPs are the main groups of scorpion venom components. Despite the existence of several studies about scorpion peptides, there are still valuable components to be discovered. Additionally, owing to the improvement of proteomics and transcriptomics, the number of peptide drugs is steadily increasing, which reflects the importance of these medications. This review evaluates available literatures on some important scorpion venom peptides with pharmaceutical activities. Given that the last three years have been dominated by the COVID-19 from the medical/pharmaceutical perspective, scorpion compounds with the potential against the coronavirus 2 (SARS-CoV-2) are discussed in this review.

A Meta-Analysis Study to Infer Voltage-Gated K+ Channels Prognostic Value in Different Cancer Types

Potassium channels are often highly expressed in cancer cells with respect to healthy ones, as they provide proliferative advantages through modulating membrane potential, calcium homeostasis, and various signaling pathways. Among potassium channels, Shaker type voltage-gated Kv channels are emerging as promising pharmacological targets in oncology. Here, we queried publicly available cancer patient databases to highlight if a correlation exists between Kv channel expression and survival rate in five different cancer types. By multiple gene comparison analysis, we found a predominant expression of KCNA2, KCNA3, and KCNA5 with respect to the other KCNA genes in skin cutaneous melanoma (SKCM), uterine corpus endometrial carcinoma (UCEC), stomach adenocarcinoma (STAD), lung adenocarcinoma (LUAD), and lung squamous cell carcinoma (LUSC). This analysis highlighted a prognostic role of KCNA3 and KCNA5 in SKCM, LUAD, LUSC, and STAD, respectively. Interestingly, KCNA3 was associated with a positive prognosis in SKCM and LUAD but not in LUSC. Results obtained by the analysis of KCNA3-related differentially expressed genes (DEGs); tumor immune cell infiltration highlighted differences that may account for such differential prognosis. A meta-analysis study was conducted to investigate the role of KCNA channels in cancer using cancer patients’ datasets. Our study underlines a promising correlation between Kv channel expression in tumor cells, in infiltrating immune cells, and survival rate.

Bioactive peptides from scorpion venoms: therapeutic scaffolds and pharmacological tools

Evolution and natural selection have endowed animal venoms, including scorpion venoms, with a wide range of pharmacological properties. Consequently, scorpions, their venoms, and/or their body parts have been used since time immemorial in traditional medicines, especially in Africa and Asia. With respect to their pharmacological potential, bioactive peptides from scorpion venoms have become an important source of scientific research. With the rapid increase in the characterization of various components from scorpion venoms, a large number of peptides are identified with an aim of combating a myriad of emerging global health problems. Moreover, some scorpion venom-derived peptides have been established as potential scaffolds helpful for drug development. In this review, we summarize the promising scorpion venoms-derived peptides as drug candidates. Accordingly, we highlight the data and knowledge needed for continuous characterization and development of additional natural peptides from scorpion venoms, as potential drugs that can treat related diseases.

Kv1.3 K+ Channel Physiology Assessed by Genetic and Pharmacological Modulation

Potassium channels are widespread over all kingdoms and play an important role in the maintenance of cellular ionic homeostasis. Kv1.3 is a voltage-gated potassium channel of the Shaker family with a wide tissue expression and a well-defined pharmacology. In recent decades, experiments mainly based on pharmacological modulation of Kv1.3 have highlighted its crucial contribution to different fundamental processes such as regulation of proliferation, apoptosis, and metabolism. These findings link channel function to various pathologies ranging from autoimmune diseases to obesity and cancer. In the present review, we briefly summarize studies employing Kv1.3 knockout animal models to confirm such roles and discuss the findings in comparison to the results obtained by pharmacological modulation of Kv1.3 in various pathophysiological settings. We also underline how these studies contributed to our understanding of channel function in vivo and propose possible future directions.

The modulation of ion channels in cancer chemo-resistance

Ion channels modulate the flow of ions into and out of a cell or intracellular organelle, leading to generation of electrical or chemical signals and regulating ion homeostasis. The abundance of ion channels in the plasma and intracellular membranes are subject to physiological and pathological regulations. Abnormal and dysregulated expressions of many ion channels are found to be linked to cancer and cancer chemo-resistance. Here, we will summarize ion channels distribution in multiple tumors. And the involvement of ion channels in cancer chemo-resistance will be highlighted.

A549 in-silico 1.0: A first computational model to simulate cell cycle dependent ion current modulation in the human lung adenocarcinoma

Lung cancer is still a leading cause of death worldwide. In recent years, knowledge has been obtained of the mechanisms modulating ion channel kinetics and thus of cell bioelectric properties, which is promising for oncological biomarkers and targets. The complex interplay of channel expression and its consequences on malignant processes, however, is still insufficiently understood. We here introduce the first approach of an in-silico whole-cell ion current model of a cancer cell, in particular of the A549 human lung adenocarcinoma, including the main functionally expressed ion channels in the plasma membrane as so far known. This hidden Markov-based model represents the electrophysiology behind proliferation of the A549 cell, describing its rhythmic oscillation of the membrane potential able to trigger the transition between cell cycle phases, and it predicts membrane potential changes over the cell cycle provoked by targeted ion channel modulation. This first A549 in-silico cell model opens up a deeper insight and understanding of possible ion channel interactions in tumor development and progression, and is a valuable tool for simulating altered ion channel function in lung cancer electrophysiology.

Review on Biological Characteristics of Kv1.3 and Its Role in Liver Diseases

The liver accounts for the largest proportion of macrophages in all solid organs of the human body. Liver macrophages are mainly composed of cytolytic cells inherent in the liver and mononuclear macrophages recruited from the blood. Monocytes recruitment occurs mainly in the context of liver injury and inflammation and can be recruited into the liver and achieve a KC-like phenotype. During the immune response of the liver, macrophages/KC cells release inflammatory cytokines and infiltrate into the liver, which are considered to be the common mechanism of various liver diseases in the early stage. Meanwhile, macrophages/KC cells form an interaction network with other liver cells, which can affect the occurrence and progression of liver diseases. From the perspective of liver disease treatment, knowing the full spectrum of macrophage activation, the underlying molecular mechanisms, and their implication in either promoting liver disease progression or repairing injured liver tissue is highly relevant from a therapeutic point of view. Kv1.3 is a subtype of the voltage-dependent potassium channel, whose function is closely related to the regulation of immune cell function. At present, there are few studies on the relationship between Kv1.3 and liver diseases, and the application of its blockers as a potential treatment for liver diseases has not been reported. This manuscript reviewed the physiological characteristics of Kv1.3, the relationship between Kv1.3 and cell proliferation and apoptosis, and the role of Kv1.3 in a variety of liver diseases, so as to provide new ideas and strategies for the prevention and treatment of liver diseases. In short, by understanding the role of Kv1.3 in regulating the functions of immune cells such as macrophages, selective blockers of Kv1.3 or compounds with similar functions can be applied to alleviate the progression of liver diseases and provide new ideas for the prevention and treatment of liver diseases.

The role of the voltage-gated potassium channel, Kv2.1 in prostate cancer cell migration

Voltage-gated potassium (Kv) channels are involved in many important cellular functions and play pivotal roles in cancer progression. The expression level of Kv2.1 was observed to be higher in the highly metastatic prostate cancer cells (PC-3), specifically in their membrane, than in immortalized prostate cells (WPMY-1 cells) and comparatively less metastatic prostate cancer cells (LNCaP and DU145 cells). However, Kv2.1 expression was significantly decreased when the cells were treated with anti-oxidants, such as N-acetylcysteine or ascorbic acid, implying that the highly expressed Kv2.1 could detect reactive oxygen species (ROS) in malignant prostate cancer cells. In addition, the blockade of Kv2.1 with stromatoxin-1 or siRNA targeting Kv2.1 significantly inhibited the migration of malignant prostate cancer cells. Our results suggested that Kv2.1 plays an important role as a ROS sensor and that it is a promising therapeutic molecular target in metastasis of prostate cancer.

Voltage-Gated Potassium Channels as Regulators of Cell Death

Ion channels allow the flux of specific ions across biological membranes, thereby determining ion homeostasis within the cells. Voltage-gated potassium-selective ion channels crucially contribute to the setting of the plasma membrane potential, to volume regulation and to the physiologically relevant modulation of intracellular potassium concentration. In turn, these factors affect cell cycle progression, proliferation and apoptosis. The present review summarizes our current knowledge about the involvement of various voltage-gated channels of the Kv family in the above processes and discusses the possibility of their pharmacological targeting in the context of cancer with special emphasis on Kv1.1, Kv1.3, Kv1.5, Kv2.1, Kv10.1, and Kv11.1.

Serum and Glucocorticoid-Inducible Kinase 1 (SGK1) in NSCLC Therapy

Non-small cell lung cancer (NSCLC) remains the most prevalent and one of the deadliest cancers worldwide. Despite recent success, there is still an urgent need for new therapeutic strategies. It is also becoming increasingly evident that combinatorial approaches are more effective than single modality treatments. This review proposes that the serum and glucocorticoid-inducible kinase 1 (SGK1) may represent an attractive target for therapy of NSCLC. Although ubiquitously expressed, SGK1 deletion in mice causes only mild defects of ion physiology. The frequent overexpression of SGK1 in tumors is likely stress-induced and provides a therapeutic window to spare normal tissues. SGK1 appears to promote oncogenic signaling aimed at preserving the survival and fitness of cancer cells. Most importantly, recent investigations have revealed the ability of SGK1 to skew immune-cell differentiation toward pro-tumorigenic phenotypes. Future studies are needed to fully evaluate the potential of SGK1 as a therapeutic target in combinatorial treatments of NSCLC. However, based on what is currently known, SGK1 inactivation can result in anti-oncogenic effects both on tumor cells and on the immune microenvironment. A first generation of small molecules to inactivate SGK1 has already been already produced.

Aquaporin-1 facilitates proliferation and invasion of gastric cancer cells via GRB7-mediated ERK and Ras activation

Gastric cancer, one of the most common malignant tumors of the digestive tract, is devoid of effective treatment owing to its highly invasive ability. Aquaporins (AQPs), transmembrane water channel proteins, has been shown to be involved in the malignancy of gastric cancer. This study aims to investigate the pathophysiological roles of AQP-1 in gastric cancer. We first demonstrated quantitative real-time polymerase chain reaction analysis and found up-regulation of AQP-1 in gastric cancer cell lines. Additionally, silence of AQP-1 inhibited cell proliferation via decrease of proliferating cell nuclear antigen (PCNA) and minichromosome maintenance complex component 2 (MCM2). Moreover, migration and invasion of gastric cancer cells were also suppressed by the interference of AQP-1. However, the tumorigenic mechanism of AQP-1 on gastric cancer is yet to be found. We demonstrated western blot analysis and found that knockdown of AQP-1 decreased protein expression of phospho (p)-GRB7 (growth factor receptor-bound protein 7) and led to a remarkable reduction of p-extracellular signal-regulated kinase (ERK) via inactivation of RAS. In general, our findings indicated that AQP-1 facilitates proliferation and invasion of gastric cancer cells via GRB7-mediated ERK and Ras activation, illuminating a novel AQP-1-RAS/ERK molecular axis as regulator in gastric cancer progression and suggesting potential implications in the treatment of gastric cancer.

Ion Channels in Cancer: Orchestrators of Electrical Signaling and Cellular Crosstalk

Ion channels are pore-forming transmembrane proteins that govern ion flux to regulate a myriad of biological processes in development, physiology, and disease. Across various types of cancer, ion channel expression and activity are often dysregulated. We review the contribution of ion channels to multiple stages of tumorigenesis based on data from in vivo model systems. As intertumoral and intratumoral heterogeneities are major obstacles in developing effective therapies, we provide perspectives on how ion channels in tumor cells and their microenvironment represent targetable vulnerabilities in the areas of tumor-stromal cell interactions, cancer neuroscience, and cancer mechanobiology.

Insight into the mechanism of cytotoxicity of membrane-permeant psoralenic Kv1.3 channel inhibitors by chemical dissection of a novel member of the family

The potassium channel Kv1.3, involved in several important pathologies, is the target of a family of psoralen-based drugs whose mechanism of action is not fully understood. Here we provide evidence for a physical interaction of the mitochondria-located Kv1.3 (mtKv1.3) and Complex I of the respiratory chain and show that this proximity underlies the death-inducing ability of psoralenic Kv1.3 inhibitors. The effects of PAP-1-MHEG (PAP-1, a Kv1.3 inhibitor, with six monomeric ethylene glycol units attached to the phenyl ring of PAP-1), a more soluble novel derivative of PAP-1 and of its various portions on mitochondrial physiology indicate that the psoralenic moiety of PAP-1 bound to mtKv1.3 facilitates the diversion of electrons from Complex I to molecular oxygen. The resulting massive production of toxic Reactive Oxygen Species leads to death of cancer cells expressing Kv1.3. In vivo, PAP-1-MHEG significantly decreased melanoma volume. In summary, PAP-1-MHEG offers insights into the mechanisms of cytotoxicity of this family of compounds and may represent a valuable clinical tool.

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The mitochondrial channel mitoKv1.3 is a promising pharmacological target.

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MitoKv1.3 interacts with Complex I of the respiratory chain.

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Psoralenic inhibitors of Kv1.3 facilitate the diversion of e⁻ from complex I to O₂.

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A novel psoralenic Kv1.3 inhibitor with increased solubility reduces melanoma volume.

Novel Therapeutic Approaches of Ion Channels and Transporters in Cancer

The expression and function of many ion channels and transporters in cancer cells display major differences in comparison to those from healthy cells. These differences provide the cancer cells with advantages for tumor development. Accordingly, targeting ion channels and transporters have beneficial anticancer effects including inhibition of cancer cell proliferation, migration, invasion, metastasis, tumor vascularization, and chemotherapy resistance, as well as promoting apoptosis. Some of the molecular mechanisms associating ion channels and transporters with cancer include the participation of oxidative stress, immune response, metabolic pathways, drug synergism, as well as noncanonical functions of ion channels. This diversity of mechanisms offers an exciting possibility to suggest novel and more effective therapeutic approaches to fight cancer. Here, we review and discuss most of the current knowledge suggesting novel therapeutic approaches for cancer therapy targeting ion channels and transporters. The role and regulation of ion channels and transporters in cancer provide a plethora of exceptional opportunities in drug design, as well as novel and promising therapeutic approaches that may be used for the benefit of cancer patients.

From Animal Poisons and Venoms to Medicines: Achievements, Challenges and Perspectives in Drug Discovery

Animal poisons and venoms are comprised of different classes of molecules displaying wide-ranging pharmacological activities. This review aims to provide an in-depth view of toxin-based compounds from terrestrial and marine organisms used as diagnostic tools, experimental molecules to validate postulated therapeutic targets, drug libraries, prototypes for the design of drugs, cosmeceuticals, and therapeutic agents. However, making these molecules applicable requires extensive preclinical trials, with some applications also demanding clinical trials, in order to validate their molecular target, mechanism of action, effective dose, potential adverse effects, as well as other fundamental parameters. Here we go through the pitfalls for a toxin-based potential therapeutic drug to become eligible for clinical trials and marketing. The manuscript also presents an overview of the current picture for several molecules from different animal venoms and poisons (such as those from amphibians, cone snails, hymenopterans, scorpions, sea anemones, snakes, spiders, tetraodontiformes, bats, and shrews) that have been used in clinical trials. Advances and perspectives on the therapeutic potential of molecules from other underexploited animals, such as caterpillars and ticks, are also reported. The challenges faced during the lengthy and costly preclinical and clinical studies and how to overcome these hindrances are also discussed for that drug candidates going to the bedside. It covers most of the drugs developed using toxins, the molecules that have failed and those that are currently in clinical trials. The article presents a detailed overview of toxins that have been used as therapeutic agents, including their discovery, formulation, dosage, indications, main adverse effects, and pregnancy and breastfeeding prescription warnings. Toxins in diagnosis, as well as cosmeceuticals and atypical therapies (bee venom and leech therapies) are also reported. The level of cumulative and detailed information provided in this review may help pharmacists, physicians, biotechnologists, pharmacologists, and scientists interested in toxinology, drug discovery, and development of toxin-based products.

Kv7 Channels in Lung Diseases

Lung diseases constitute a global health concern causing disability. According to WHO in 2016, respiratory diseases accounted for 24% of world population mortality, the second cause of death after cardiovascular diseases. The Kv7 channels family is a group of voltage-dependent K⁺ channels (Kv) encoded by KCNQ genes that are involved in various physiological functions in numerous cell types, especially, cardiac myocytes, smooth muscle cells, neurons, and epithelial cells. Kv7 channel α-subunits are regulated by KCNE1–5 ancillary β-subunits, which modulate several characteristics of Kv7 channels such as biophysical properties, cell-location, channel trafficking, and pharmacological sensitivity. Kv7 channels are mainly expressed in two large groups of lung tissues: pulmonary arteries (PAs) and bronchial tubes. In PA, Kv7 channels are expressed in pulmonary artery smooth muscle cells (PASMCs); while in the airway (trachea, bronchus, and bronchioles), Kv7 channels are expressed in airway smooth muscle cells (ASMCs), airway epithelial cells (AEPs), and vagal airway C-fibers (VACFs). The functional role of Kv7 channels may vary depending on the cell type. Several studies have demonstrated that the impairment of Kv7 channel has a strong impact on pulmonary physiology contributing to the pathophysiology of different respiratory diseases such as cystic fibrosis, asthma, chronic obstructive pulmonary disease, chronic coughing, lung cancer, and pulmonary hypertension. Kv7 channels are now recognized as playing relevant physiological roles in many tissues, which have encouraged the search for Kv7 channel modulators with potential therapeutic use in many diseases including those affecting the lung. Modulation of Kv7 channels has been proposed to provide beneficial effects in a number of lung conditions. Therefore, Kv7 channel openers/enhancers or drugs acting partly through these channels have been proposed as bronchodilators, expectorants, antitussives, chemotherapeutics and pulmonary vasodilators.

Potassium channels and their role in glioma: A mini review

K⁺ channels regulate a multitude of biological processes and play important roles in a variety of diseases by controlling potassium flow across cell membranes. They are widely expressed in the central and peripheral nervous system. As a malignant tumor derived from nerve epithelium, glioma has the characteristics of high incidence, high recurrence rate, high mortality rate, and low cure rate. Since glioma cells show invasive growth, current surgical methods cannot completely remove tumors. Adjuvant chemotherapy is still needed after surgery. Because the blood-brain barrier and other factors lead to a lower effective concentration of chemotherapeutic drugs in the tumor, the recurrence rate of residual lesions is extremely high. Therefore, new therapeutic methods are needed. Numerous studies have shown that different K⁺ channel subtypes are differentially expressed in glioma cells and are involved in the regulation of the cell cycle of glioma cells to arrest them at different stages of the cell cycle. Increasing evidence suggests that K⁺ channels express in glioma cells and regulate glioma cell behaviors such as cell cycle, proliferation and apoptosis. This review article aims to summarize the current knowledge on the function of K⁺ channels in glioma, suggests K⁺ channels participating in the development of glioma.

Voltage-Gated K+/Na+ Channels and Scorpion Venom Toxins in Cancer

Ion channels have recently been recognized as novel therapeutic targets in cancer research since they are overexpressed in different histological tissues, and their activity is linked to proliferation, tumor progression, angiogenesis, metastasis, and apoptosis. Voltage gated-potassium channels (VGKC) are involved in cell proliferation, cancer progression, cell cycle transition, and apoptosis. Moreover, voltage-dependent sodium channels (VGSC) contribute to decreases in extracellular pH, which, in turn, promotes cancer cell migration and invasion. Furthermore, VGSC and VGKC modulate voltage-sensitive Ca2+ channel activity by controlling the membrane potential and regulating Ca2+ influx, which functions as a second messenger in processes related to proliferation, invasion, migration, and metastasis. The subgroup of these types of channels that have shown a high oncogenic potential have become known as "oncochannels", and the evidence has highlighted them as key potential therapeutic targets. Scorpion venoms contain a high proportion of peptide toxins that act by modulating voltage-gated Na+/K+ channel activity. Increasing scientific data have pointed out that scorpion venoms and their toxins can affect the activity of oncochannels, thus showing their potential for anticancer therapy. In this review, we provide an update of the most relevant voltage-gated Na+\K+ ion channels as cellular targets and discuss the possibility of using scorpion venom and toxins for anticancer therapy.

Scorpion Toxins and Ion Channels: Potential Applications in Cancer Therapy

Apoptosis, a genetically directed process of cell death, has been studied for many years, and the biochemical mechanisms that surround it are well known and described. There are at least three pathways by which apoptosis occurs, and each pathway depends on extra or intracellular processes for activation. Apoptosis is a vital process, but disturbances in proliferation and cell death rates can lead to the development of diseases like cancer. Several compounds, isolated from scorpion venoms, exhibit inhibitory effects on different cancer cells. Indeed, some of these compounds can differentiate between healthy and cancer cells within the same tissue. During the carcinogenic process, morphological, biochemical, and biological changes occur that enable these compounds to modulate cancer but not healthy cells. This review highlights cancer cell features that enable modulation by scorpion neurotoxins. The properties of the isolated scorpion neurotoxins in cancer cells and the potential uses of these compounds as alternative treatments for cancer are discussed.

Pleiotropic Anticancer Properties of Scorpion Venom Peptides: Rhopalurus princeps Venom as an Anticancer Agent

To date, the success of conventional chemotherapy, radiotherapy, and targeted biological therapies in cancer treatment is not satisfactory. The main reasons for such outcomes rely on low target selectivity, primarily in chemo- and radiotherapy, ineffectiveness to metastatic disease, drug resistance, and severe side effects. Although immune checkpoint inhibitors may offer better clinical promise, success is still limited. Since cancer is a complex systemic disease, the need for new therapeutic modalities that can target or block several steps of cancer cell characteristics, modulate or repolarize immune cells, and are less toxic to healthy tissues is essential. Of these promising therapeutic modalities are pleiotropic natural products in which scorpion venom (SV) is an excellent example. SV consists of complex bioactive peptides that are disulfide-rich of different peptides’ length, potent, stable, and exerts various multi-pharmacological actions. SV peptides also contain ion channel inhibitors. These ion channels are dysregulated and overexpressed in cancer cells, and play essential roles in cancer development and invasion, as well as depolarizing immune cells. Furthermore, SV has been found to induce cancer cell apoptosis, and inhibit cancer cells proliferation, invasion, metastasis, and angiogenesis. In the current review, we are presenting data that show the pleiotropic effect of SV against different types of human cancer as well as revealing one potential anticancer agent, Rhopalurus princeps venom. Furthermore, we are addressing what is needed to be done to translate these potential cancer therapeutics to the clinic.

Ion Channels in Lung Cancer

Ion channels are a major class of membrane proteins that play central roles in signaling within and among cells, as well as in the coupling of extracellular events with cellular responses. Dysregulated ion channel activity plays a causative role in many diseases including cancer. Here, we will review their role in lung cancer. Lung cancer is one of the most frequently diagnosed cancers, and it causes the highest number of deaths of all cancer types. The overall 5-year survival rate of lung cancer patients is only 19% and decreases to 5% when patients are diagnosed with stage IV. Thus, new therapeutical strategies are urgently needed. The important contribution of ion channels to the progression of various types of cancer has been firmly established so that ion channel-based therapeutic concepts are currently developed. Thus far, the knowledge on ion channel function in lung cancer is still relatively limited. However, the published studies clearly show the impact of ion channel inhibitors on a number of cellular mechanisms underlying lung cancer cell aggressiveness such as proliferation, migration, invasion, cell cycle progression, or adhesion. Additionally, in vivo experiments reveal that ion channel inhibitors diminish tumor growth in mice. Furthermore, some studies give evidence that ion channel inhibitors can have an influence on the resistance or sensitivity of lung cancer cells to common chemotherapeutics such as paclitaxel or cisplatin.

Clinical Use of Toxic Proteins and Peptides from Tian Hua Fen and Scorpion Venom

Traditional Chinese Medicine (TCM) has been practiced in China for thousands of years. As a complementary and alternative treatment, herbal medicines that are frequently used in the TCM are the most accepted in the Western world. However, animal materials, which are equally important in the TCM practice, are not well-known in other countries. On the other hand, the Chinese doctors had documented the toxic profiles of hundreds of animals and plants thousand years ago. Furthermore, they saw the potential benefits of these materials and used their toxic properties to treat a wide variety of diseases, such as heavy pain and cancer. Since the 50s of the last century, efforts of the Chinese government and societies to modernize TCM have achieved tremendous scientific results in both laboratory and clinic. A number of toxic proteins have been isolated and their functions identified. Although most of the literature was written in Chinese, this review provide a summary, in English, regarding our knowledge of the clinical use of the toxic proteins isolated from a plant, Tian Hua Fen, and an animal, scorpion, both of which are famous toxic prescriptions in TCM.

Renal Alterations Induced by the Venom of Colombian Scorpion Centruroides Margaritatus

BACKGROUND

Scorpion venom causes renal injury and affects vascular ion-channels function. Centruroides margaritatus scorpion is found in Colombia and is frequently the cause of envenomation accidents; however, its renal impact has never been investigated.

OBJECTIVE

To evaluate the effects of C. margaritatus venom (CmV) on renal parameters using isolated rat kidney and renal cell culture models.

METHODS

Wistar rats (n = 5, weighing 240-300 g) were first perfused with Krebs-Henseleit solution containing 6 g 100 mL-1 bovine serum albumin. After 30 minutes, the kidneys were perfused with CmV to a final concentration of 10 μgmL-1; evaluation was performed by measuring Perfusion Pressure (PP), Renal Vascular Resistance (RVR), Urinary Flow (UF), Glomerular Filtration Rate (GFR), and percentage of electrolyte tubular transport. Moreover, kidney histological analyses and cell cytotoxicity in renal tubule epithelial cells (MDCK) and proximal tubular cells (LLC-MK2) were assessed.

RESULTS

CmV increased PP and RVR 60 min after perfusion. On the other hand, UF, GFR, and the percentages of sodium, potassium and chloride tubular transport decreased after experimental envenomation. UF dropped after 120 min, while GFR and percentage of electrolyte tubular transport diminished after 60, 90 and 120 min. CmV was not toxic to MDCK cell line but reduced the viability of LLC-MK2 cells at concentrations ranging from 6.25 to 200 μgmL-1. Histological analyses disclosed hydropic degeneration, edema, and protein deposits. Flow cytometry disclosed that cell death occurred predominantly by necrosis.

CONCLUSION

Our results suggest that C. margaritatus venom can trigger renal impairment, mainly in the proximal kidney tubule.

The recent progresses in shRNA-nanoparticle conjugate as a therapeutic approach

The recent trend of gene therapy is using short hairpin RNA conjugated with different types of nanoparticles. shRNAs have a significant role in gene silencing and have a promising role in treating several genetic and infectious diseases. There are several drawbacks of delivering bare shRNA in the blood as they are fragile in nature and readily degradable. To overcome this problem shRNAs can be conjugated with nanoparticles for a safe deliver. In this article several nanoparticles are mentioned which play significant role in delivery of this payload. On one hand they protect the shRNA from degradation on the other they help to penetrate this large molecule in to the cell. Some of these nanoconjugates are in clinical trials and have a promising role in treatment of diseases.

Scorpion Venom: New Promise in the Treatment of Cancer

Cancer is a public health problem due to its high worldwide morbimortality. Current treatment protocols do not guarantee complete remission, which has prompted to search for new and more effective antitumoral compounds. Several substances exhibiting cytostatic and cytotoxic effects over cancer cells might contribute to the treatment of this pathology. Some studies indicate the presence of such substances in scorpion venom. In this review, we report characteristics of the principal scorpion venom components found in recent literature and their potential activity against tumor cells.  There are different toxin groups present in the venom, and it seems that their mode of actions involves ionic channel blocking, disruption of the cell membrane integrity and damage to internal cell organelles.  These properties make good prospects for studies on drugs and adjuvants in cancer treatment.

Scorpion toxins targeting Kv1.3 channels: insights into immunosuppression

Scorpion venoms are natural sources of molecules that have, in addition to their toxic function, potential therapeutic applications. In this source the neurotoxins can be found especially those that act on potassium channels. Potassium channels are responsible for maintaining the membrane potential in the excitable cells, especially the voltage-dependent potassium channels (Kv), including Kv1.3 channels. These channels (Kv1.3) are expressed by various types of tissues and cells, being part of several physiological processes. However, the major studies of Kv1.3 are performed on T cells due its importance on autoimmune diseases. Scorpion toxins capable of acting on potassium channels (KTx), mainly on Kv1.3 channels, have gained a prominent role for their possible ability to control inflammatory autoimmune diseases. Some of these toxins have already left bench trials and are being evaluated in clinical trials, presenting great therapeutic potential. Thus, scorpion toxins are important natural molecules that should not be overlooked in the treatment of autoimmune and other diseases.

Tumor-reducing effect of the clinically used drug clofazimine in a SCID mouse model of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) represents the most common form of pancreatic cancer with rising incidence in developing countries. Unfortunately, the overall 5-year survival rate is still less than 5%. The most frequent oncogenic mutations in PDAC are loss-of function mutations in p53 and gain-of-function mutations in KRAS. Here we show that clofazimine (Lamprene), a drug already used in the clinic for autoimmune diseases and leprosy, is able to efficiently kill in vitro five different PDAC cell lines harboring p53 mutations. We provide evidence that clofazimine induces apoptosis in PDAC cells with an EC₅₀ in the μM range via its specific inhibitory action on the potassium channel Kv1.3. Intraperitoneal injection of clofazimine resulted in its accumulation in the pancreas of mice 8 hours after administration. Using an orthotopic PDAC xenotransplantation model in SCID beige mouse, we show that clofazimine significantly and strongly reduced the primary tumor weight. Thus, our work identifies clofazimine as a promising therapeutic agent against PDAC and further highlights ion channels as possible oncological targets.

Potassium channel inhibitors induce oxidative stress in breast cancer cells

Background

Antioxidant levels increase to protect cell homeostasis when oxidant generation is increased by drug or inhibitor treatment. If the oxidant–antioxidant equilibrium is disrupted, oxidative stress will occur.

Objectives

To determine the effects of various potassium channel inhibitors in the disruption of oxidant–antioxidant equilibrium in breast cancer cell lines with various phenotypes.

Methods

MCF-7 or MDA-MB-231 breast cancer cells were treated with tetraethylammonium chloride (5 mM; TEA), 4-aminopyridine (5 mM; 4-AP), margatoxin (25 nM; MgTX), or astemizole (200 nM; AST). After treatment, total antioxidant, oxidant, and oxidative stress levels were determined.

Results

Incubation with TEA, 4-AP, MgTX, and AST increased oxidative stress in both MCF-7 and MDA-MB-231 cells (P < 0.001). Specific inhibitors of calcium-activated potassium channels and ether á go-go 1-related potassium channels produce greater oxidative stress than other inhibitors in MCF-7 breast cancer cells, whereas in MDA-MB-231 cells, the nonselective channel inhibitor 4-AP produces the greatest oxidative stress.

Conclusions

Potassium channel inhibitors used in our study disrupted the antioxidant–oxidant equilibrium and increased oxidative stress in the cancer cell lines. Although all of the channel inhibitors increased oxidative stress in cells, TEA and AST were the most effective inhibitors in MCF-7 cells. 4-AP was the most effective inhibitor in MDA-MB-231 cells. Voltage-gated potassium channels are attractive targets for anticancer therapy, and their inhibitors may enhance the effects of anticancer drugs.

Regulation of Proliferation by a Mitochondrial Potassium Channel in Pancreatic Ductal Adenocarcinoma Cells

Previous results link the mitochondrial potassium channel Kv1.3 (mitoKv1.3) to the regulation of apoptosis. By synthesizing new, mitochondria-targeted derivatives (PAPTP and PCARBTP) of PAP-1, a specific membrane-permeant Kv1.3 inhibitor, we have recently provided evidence that both drugs acting on mitoKv1.3 are able to induce apoptosis and reduce tumor growth in vivo without affecting healthy tissues and cells. In the present article, by exploiting these new drugs, we addressed the question whether mitoKv1.3 contributes to the regulation of cell proliferation as well. When used at low concentrations, which do not compromise cell survival, both drugs slightly increased the percentage of cells in S phase while decreased the population at G0/G1 stage of cells from two different pancreatic ductal adenocarcinoma lines. Our data suggest that the observed modulation is related to ROS levels within the cells, opening the way to link mitochondrial ion channel function to downstream, ROS-related signaling events that might be important for cell cycle progression.

Direct Pharmacological Targeting of a Mitochondrial Ion Channel Selectively Kills Tumor Cells In Vivo

The potassium channel Kv1.3 is highly expressed in the mitochondria of various cancerous cells. Here we show that direct inhibition of Kv1.3 using two mitochondria-targeted inhibitors alters mitochondrial function and leads to reactive oxygen species (ROS)-mediated death of even chemoresistant cells independently of p53 status. These inhibitors killed 98% of ex vivo primary chronic B-lymphocytic leukemia tumor cells while sparing healthy B cells. In orthotopic mouse models of melanoma and pancreatic ductal adenocarcinoma, the compounds reduced tumor size by more than 90% and 60%, respectively, while sparing immune and cardiac functions. Our work provides direct evidence that specific pharmacological targeting of a mitochondrial potassium channel can lead to ROS-mediated selective apoptosis of cancer cells in vivo, without causing significant side effects.

Ion channels or aquaporins as novel molecular targets in gastric cancer

Gastric cancer (GC) is a common disease with few effective treatment choices and poor prognosis, and has the second-highest mortality rates among all cancers worldwide. Dysregulation and/or malfunction of ion channels or aquaporins (AQPs) are common in various human cancers. Furthermore, ion channels are involved in numerous important aspects of the tumor aggressive phonotype, such as proliferation, cell cycle, apoptosis, motility, migration, and invasion. Indeed, by localizing in the plasma membrane, ion channels or AQPs can sense and respond to extracellular environment changes; thus, they play a crucial role in cell signaling and cancer progression. These findings have expanded a new area of pharmaceutical exploration for various types of cancer, including GC. The involvement of multiple ion channels, such as voltage-gated potassium and sodium channels, intracellular chloride channels, ‘transient receptor potential’ channels, and AQPs, which have been shown to facilitate the pathogenesis of other tumors, also plays a role in GC. In this review, an overview of ion channel and aquaporin expression and function in carcinogenesis of GC is presented. Studies of ion channels or AQPs will advance our understanding of the molecular genesis of GC and may identify novel and effective targets for the clinical application of GC.

Regulation of voltage-gated potassium channels attenuates resistance of side-population cells to gefitinib in the human lung cancer cell line NCI-H460

BACKGROUND

Side-population (SP) cells that exclude anti-cancer drugs have been found in various tumor cell lines. Moreover, SP cells have a higher proliferative potential and drug resistance than main population cells (Non-SP cells). Also, several ion channels are responsible for the drug resistance and proliferation of SP cells in cancer.

METHODS

To confirm the expression and function of voltage-gated potassium (Kv) channels of SP cells, these cells, as well as highly expressed ATP-binding cassette (ABC) transporters and stemness genes, were isolated from a gefitinib-resistant human lung adenocarcinoma cell line (NCI-H460), using Hoechst 33342 efflux.

RESULTS

In the present study, we found that mRNA expression of Kv channels in SP cells was different compared to Non-SP cells, and the resistance of SP cells to gefitinib was weakened with a combination treatment of gefitinib and Kv channel blockers or a Kv7 opener, compared to single-treatment gefitinib, through inhibition of the Ras-Raf signaling pathway.

CONCLUSIONS

The findings indicate that Kv channels in SP cells could be new targets for reducing the resistance to gefitinib.