The Role of Chloride Channels in the Multidrug Resistance

Chloride channels and mast cell function: pioneering new frontiers in IBD therapy

Emerging evidence indicates that chloride channels (ClCs) significantly affect the pathogenesis of inflammatory bowel disease (IBD) through their regulatory roles in mast cell function and epithelial integrity. IBD, encompassing conditions such as Crohn's disease and ulcerative colitis, involves chronic inflammation of the gastrointestinal tract, where channels influence immune responses, fluid balance, and cellular signalling pathways essential for maintaining mucosal homeostasis. This review examines the specific roles of ClC in mast cells, focussing on the regulation of mast cell activation, degranulation, cytokine release, and immune cell recruitment in inflamed tissues. Key channels, including Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) and ClC-2, are discussed in detail because of their involvement in maintaining intestinal epithelial barrier function, a critical factor disrupted in IBD. For example, CFTR facilitates chloride ion transport across epithelial cells, which is essential for mucosal hydration and maintenance of the intestinal barrier. Reduced CFTR function can compromise this barrier, permitting microbial antigens to penetrate the underlying tissues and triggering excessive immune responses. ClC-2, another chloride channel expressed in mast cells and epithelial cells, supports tight junction integrity, contributes to barrier function, and reduces intestinal permeability. Dysregulation of these channels is linked to altered mast cell activity and excessive release of pro-inflammatory mediators, exacerbating IBD symptoms, such as diarrhoea, abdominal pain, and tissue damage. Here, we review recent pharmacological strategies targeting ClC, including CFTR potentiators and ClC-2 activators, which show the potential to mitigate inflammatory responses. Additionally, experimental approaches for selective modulation of chloride channels in mast cells have been explored. Although targeting ClC offers promising therapeutic avenues, challenges remain in achieving specificity and minimizing side effects. This review highlights the therapeutic potential of Cl channel modulation in mast cells as a novel approach for IBD treatment, aiming to reduce inflammation and restore intestinal homeostasis in affected patients.

Osmotic stress influences microtubule drug response via WNK1 kinase signaling

Ion homeostasis is critical for numerous cellular processes, and disturbances in ionic balance underlie diverse pathological conditions, including cancer progression. Targeting ion homeostasis is even considered as a strategy to treat cancer. However, very little is known about how ion homeostasis may influence anticancer drug response. In a genome-wide CRISPR-Cas9 resistance drug screen, we identified and validated the master osmostress regulator WNK1 kinase as a modulator of the response to the mitotic inhibitor rigosertib. Osmotic stress and WNK1 inactivation lead to an altered response not only to rigosertib treatment but also to other microtubule-related drugs, minimizing the prototypical mitotic arrest produced by these compounds. This effect is due to an alteration in microtubule stability and polymerization dynamics, likely maintained by fluctuations in intracellular molecular crowding upon WNK1 inactivation. This promotes resistance to microtubule depolymerizing compounds, and increased sensitivity to microtubule stabilizing drugs. In summary, our data proposes WNK1 osmoregulation activity as an important modulator for microtubule-associated chemotherapy response.

Hypoxia, Ion Channels and Glioblastoma Malignancy

The malignancy of glioblastoma (GBM), the most aggressive type of human brain tumor, strongly correlates with the presence of hypoxic areas within the tumor mass. Oxygen levels have been shown to control several critical aspects of tumor aggressiveness, such as migration/invasion and cell death resistance, but the underlying mechanisms are still unclear. GBM cells express abundant K+ and Cl- channels, whose activity supports cell volume and membrane potential changes, critical for cell proliferation, migration and death. Volume-regulated anion channels (VRAC), which mediate the swelling-activated Cl- current, and the large-conductance Ca2+-activated K+ channels (BK) are both functionally upregulated in GBM cells, where they control different aspects underlying GBM malignancy/aggressiveness. The functional expression/activity of both VRAC and BK channels are under the control of the oxygen levels, and these regulations are involved in the hypoxia-induced GBM cell aggressiveness. The present review will provide a comprehensive overview of the literature supporting the role of these two channels in the hypoxia-mediated GBM malignancy, suggesting them as potential therapeutic targets in the treatment of GBM.

Physiological roles of chloride ions in bodily and cellular functions

Physiological roles of Cl-, a major anion in the body, are not well known compared with those of cations. This review article introduces: (1) roles of Cl- in bodily and cellular functions; (2) the range of cytosolic Cl- concentration ([Cl-]c); (3) whether [Cl-]c could change with cell volume change under an isosmotic condition; (4) whether [Cl-]c could change under conditions where multiple Cl- transporters and channels contribute to Cl- influx and efflux in an isosmotic state; (5) whether the change in [Cl-]c could be large enough to act as signals; (6) effects of Cl- on cytoskeletal tubulin polymerization through inhibition of GTPase activity and tubulin polymerization-dependent biological activity; (7) roles of cytosolic Cl- in cell proliferation; (8) Cl--regulatory mechanisms of ciliary motility; (9) roles of Cl- in sweet/umami taste receptors; (10) Cl--regulatory mechanisms of with-no-lysine kinase (WNK); (11) roles of Cl- in regulation of epithelial Na+ transport; (12) relationship between roles of Cl- and H+ in body functions.

Autism Spectrum Disorder: Neurodevelopmental Risk Factors, Biological Mechanism, and Precision Therapy

Autism spectrum disorder (ASD) is a heterogeneous, behaviorally defined neurodevelopmental disorder. Over the past two decades, the prevalence of autism spectrum disorders has progressively increased, however, no clear diagnostic markers and specifically targeted medications for autism have emerged. As a result, neurobehavioral abnormalities, neurobiological alterations in ASD, and the development of novel ASD pharmacological therapy necessitate multidisciplinary collaboration. In this review, we discuss the development of multiple animal models of ASD to contribute to the disease mechanisms of ASD, as well as new studies from multiple disciplines to assess the behavioral pathology of ASD. In addition, we summarize and highlight the mechanistic advances regarding gene transcription, RNA and non-coding RNA translation, abnormal synaptic signaling pathways, epigenetic post-translational modifications, brain-gut axis, immune inflammation and neural loop abnormalities in autism to provide a theoretical basis for the next step of precision therapy. Furthermore, we review existing autism therapy tactics and limits and present challenges and opportunities for translating multidisciplinary knowledge of ASD into clinical practice.

Progress in the studies on the molecular mechanisms associated with multidrug resistance in cancers

Chemotherapy is one of the important methods to treat cancer, and the emergence of multidrug resistance (MDR) is one major cause for the failure of cancer chemotherapy. Almost all anti-tumor drugs develop drug resistance over a period of time of application in cancer patients, reducing their effects on killing cancer cells. Chemoresistance can lead to a rapid recurrence of cancers and ultimately patient death. MDR may be induced by multiple mechanisms, which are associated with a complex process of multiple genes, factors, pathways, and multiple steps, and today the MDR-associated mechanisms are largely unknown. In this paper, from the aspects of protein-protein interactions, alternative splicing (AS) in pre-mRNA, non-coding RNA (ncRNA) mediation, genome mutations, variance in cell functions, and influence from the tumor microenvironment, we summarize the molecular mechanisms associated with MDR in cancers. In the end, prospects for the exploration of antitumor drugs that can reverse MDR are briefly discussed from the angle of drug systems with improved targeting properties, biocompatibility, availability, and other advantages.

Ion Channels in Multiple Myeloma: Pathogenic Role and Therapeutic Perspectives

Ion channels are pore-forming proteins that allow ions to flow across plasma membranes and intracellular organelles in both excitable and non-excitable cells. They are involved in the regulation of several biological processes (i.e., proliferation, cell volume and shape, differentiation, migration, and apoptosis). Recently, the aberrant expression of ion channels has emerged as an important step of malignant transformation, tumor progression, and drug resistance, leading to the idea of “onco-channelopathy”. Here, we review the contribution of ion channels and transporters in multiple myeloma (MM), a hematological neoplasia characterized by the expansion of tumor plasma cells (MM cells) in the bone marrow (BM). Deregulation of ion channels sustains MM progression by modulating intracellular pathways that promote MM cells’ survival, proliferation, and drug resistance. Finally, we focus on the promising role of ion channels as therapeutic targets for the treatment of MM patients in a combination strategy with currently used anti-MM drugs to improve their cytotoxic activity and reduce adverse effects.

Novel Perspective of Cardiovascular Diseases: Volume-Regulatory Anion Channels in the Cell Membrane

Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality worldwide. Although there are established mechanisms and preventions for CVDs, they are not totally elucidative and effective. Emerging evidence suggests that the dysregulation of ion channels in the cell membranes underpins the dysfunction of the cardiovascular system. To date, a variety of cation channels have been widely recognized as important targets for the treatment of CVDs. As a critical component of the anion channels, the volume-regulated anion channel (VRAC) is involved in a series of cell functions by the volume regulation and maintenance of membrane homeostasis. It has been confirmed to play crucial roles in cell action potential generation, cell proliferation, differentiation and apoptosis, and the VRAC appears to be a major participant in metabolic processes during CVDs. This review summarizes the current evidence and progress concerning the VRAC, to determine the future directions and challenges for CVDs for both preventive and therapeutic purposes.