Transient receptor potential melastatin 4 contributes to early-stage endothelial injury induced by arsenic trioxide

Role of the transient receptor potential melastatin 4 in inhibition effect of arsenic trioxide on the tumor biological features of colorectal cancer cell

Background

To investigate the effects of arsenic trioxide (ATO) on human colorectal cancer cells (HCT116) growth and the role of transient receptor potential melastatin 4 (TRPM4) channel in this process.

Methods

The viability of HCT116 cells was assessed using the CCK-8 assay. Western blot analysis was employed to examine the protein expression of TRPM4. The apoptosis of HCT116 cells was determined using TUNEL and Flow cytometry. Cell migration was assessed through the cell scratch recovery assay and Transwell cell migration assay. Additionally, Transwell cell invasion assay was performed to determine the invasion ability of HCT116 cells.

Results

ATO suppressed the viability of HCT116 cells in a dose-dependent manner, accompanied by a decline in cell migration and invasion, and an increase in apoptosis. 9-phenanthroline (9-Ph), a specific inhibitor of TRPM4, abrogated the ATO-induced upregulation of TRPM4 expression. Additionally, blocking TRPM4 reversed the effects of ATO on HCT116 cells proliferation, including restoration of cell viability, migration and invasion, as well as the inhibition of apoptosis.

Conclusion

ATO inhibits CRC cell growth by inducing TRPM4 expression, our findings indicate that ATO is a promising therapeutic strategy and TRPM4 may be a novel target for the treatment of CRC.

Transient receptor potential channel TRPM4 favors oxidized low-density lipoprotein-induced coronary endothelial cell dysfunction via a mechanism involving ferroptosis

Accelerating the repair of damaged endothelium can effectively inhibit the progression of atherosclerosis (AS). Transient receptor potential channel TRPM4 is a non-selective cation channel activated by internal Ca2+, which is expressed in endothelial cells. This study aimed to reveal the potential role of TRPM4 in AS along with the mechanism. Human coronary artery endothelial cells (HCAECs) induced by ox-LDL was regarded as an in vitro model. The impacts of TRPM4 knockdown on cellular inflammation response, oxidative stress, normal endothelial function and lipid peroxidation were evaluated. Given that ferroptosis promotes AS progression, the effects of TRPM4 on intracellular iron ions and ferroptosis-related proteins was determined. Afterwards, HCAECs were treated with ferroptosis inducer erastin, and the influence of ferroptosis in the cellular model was revealed. TRPM4 was elevated in response to ox-LDL treatment in HCAECs. TRPM4 knockdown reduced the inflammation response, oxidative stress and lipid peroxidation caused by ox-LDL, and maintained the normal function of HCAECs. Erastin treatment destroyed the impacts of TRPM4 knockdown that are beneficial for cells to resist ox-LDL, showing the enhancement of the above adverse factors. Together, this study found that TRPM4 knockdown reduced ox-LDL-induced inflammation, oxidative stress, and dysfunction in HCAECs, possibly via a mechanism involving Fe2+ and ferroptosis-related proteins.

miR-133a-3p/TRPM4 axis improves palmitic acid induced vascular endothelial injury

Background: Vascular endothelial injury is a contributing factor to the development of atherosclerosis and the resulting cardiovascular diseases. One particular factor involved in endothelial cell apoptosis and atherosclerosis is palmitic acid (PA), which is a long-chain saturated fatty acid. In addition, transient receptor potential melastatin 4 (TRPM4), a non-selective cation channel, plays a significant role in endothelial dysfunction caused by various factors related to cardiovascular diseases. Despite this, the specific role and mechanisms of TRPM4 in atherosclerosis have not been fully understood. Methods: The protein and mRNA expressions of TRPM4, apoptosis - and inflammation-related factors were measured after PA treatment. The effect of TRPM4 knockout on the protein and mRNA expression of apoptosis and inflammation-related factors was detected. The changes of intracellular Ca2+, mitochondrial membrane potential, and reactive oxygen species were detected by Fluo-4 AM, JC-1, and DCFH-DA probes, respectively. To confirm the binding of miR-133a-3p to TRPM4, a dual luciferase reporter gene assay was conducted. Finally, the effects of miR-133a-3p and TRPM4 on intracellular Ca2+, mitochondrial membrane potential, and reactive oxygen species were examined. Results: Following PA treatment, the expression of TRPM4 increases, leading to calcium overload in endothelial cells. This calcium influx causes the assemblage of Bcl-2, resulting in the opening of mitochondrial calcium channels and mitochondrial damage, ultimately triggering apoptosis. Throughout this process, the mRNA and protein levels of IL-1β, ICAM-1, and VCAM1 significantly increase. Database screenings and luciferase assays have shown that miR-133a-3p preferentially binds to the 3'UTR region of TRPM4 mRNA, suppressing TRPM4 expression. During PA-induced endothelial injury, miR-133a-3p is significantly decreased, but overexpression of miR-133a-3p can attenuate the progression of endothelial injury. On the other hand, overexpression of TRPM4 counteracts the aforementioned changes. Conclusion: TRPM4 participates in vascular endothelial injury caused by PA. Therefore, targeting TRPM4 or miR-133a-3p may offer a novel pharmacological approach to preventing endothelial injury.

Phytochemicals in the Management of Arsenic Toxicity

Arsenic toxicity is a major concern due to its deleterious consequences for human health. Rapid industrialization also has weakened the quality of the environment by introducing pollutants that may disrupt balanced ecosystems, adversely and irreversibly impacting humans, plants, and animals. Arsenic, an important toxicant among all environmental hazards, can lead to several detrimental effects on cells and organs, impacting the overall quality of life. Nevertheless, arsenic also has a rich history as a chemotherapeutic agent used in ancient days for the treatment of diseases such as malaria, cancer, plague, and syphilis when other chemotherapeutic agents were yet to be discovered. Arsenicosis-mediated disorders remain a serious problem due to the lack of effective therapeutic options. Initially, chelation therapy was used to metabolically eliminate arsenic by forming a complex, but adverse effects limited their pharmacological use. More recently, plant-based products have been found to provide significant relief from the toxic effects of arsenic poisoning. They act by different mechanisms affecting various cellular processes. Phytoconstituents such as curcumin, quercetin, diallyl trisulfide, thymoquinone, and others act via various molecular pathways, primarily by attenuating oxidative damage, membrane damage, DNA damage, and proteinopathies. Nonetheless, most of the phytochemicals reviewed here protect against the adverse effects of metal or metalloid exposure, supporting their consideration as alternatives to chelation therapy. These agents, if used prophylactically and in conjunction with other chemotherapeutic agents, may provide an effective approach for management of arsenic toxicity. In a few instances, such strategies like coadministration of phytochemicals with a known chelating agent have led to more pronounced elimination of arsenic from the body with lesser off-site adverse effects. This is possible because combination treatment ensures the use of a reduced dose of chelating agent with a phytochemical without compromising treatment. Thus, these therapies are more practical than conventional therapeutic agents in ameliorating arsenic-mediated toxicity. This review summarizes the potential of phytochemicals in alleviating arsenic toxicity on the basis of available experimental and clinical evidence.

Arsenic exposure from drinking water and endothelial dysfunction in Bangladeshi adolescents

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide, with ∼80% of CVD-related deaths occurring in low- and middle-income countries. Growing evidence suggests that chronic arsenic exposure may contribute to CVD through its effect on endothelial function in adults. However, few studies have examined the influence of arsenic exposure on cardiovascular health in children and adolescents. To examine arsenic's relation to preclinical markers of endothelial dysfunction, we enrolled 200 adolescent children (ages 15-19 years; median 17) of adult participants in the Health Effects of Arsenic Longitudinal Study (HEALS), in Araihazar, Bangladesh. Participants' arsenic exposure was determined by recall of lifetime well usage for drinking water. As part of HEALS, wells were color-coded to indicate arsenic level (<10 μg/L, 10-50 μg/L, >50 μg/L). Endothelial function was measured by recording fingertip arterial pulsatile volume change and reactive hyperemia index (RHI) score, an independent CVD risk factor, was calculated from these measurements. In linear regression models adjusted for participant's sex, age, education, maternal education, land ownership and body weight, individuals who reported always drinking water from wells with >50 μg/L arsenic had a 11.75% lower level of RHI (95% CI: -21.26, -1.09, p = 0.03), as compared to participants who drank exclusively from wells with ≤50 μg/L arsenic. Sex-stratified analyses suggest that these associations were stronger in female participants. As compared to individuals who drank exclusively from wells with ≤50 μg/L arsenic, the use of wells with >50 μg/L arsenic was associated with 14.36% lower RHI (95% CI: -25.69, -1.29, p = 0.03) in females, as compared to 5.35% lower RHI (95% CI: -22.28, 15.37, p = 0.58) in males for the same comparison. Our results suggest that chronic arsenic exposure may be related to endothelial dysfunction in adolescents, especially among females. Further work is needed to confirm these findings and examine whether these changes may increase risk of later adverse cardiovascular health events.

Pharmacological Modulation and (Patho)Physiological Roles of TRPM4 Channel—Part 1: Modulation of TRPM4

Transient receptor potential melastatin 4 is a unique member of the TRPM protein family and, similarly to TRPM5, is Ca²⁺-sensitive and permeable to monovalent but not divalent cations. It is widely expressed in many organs and is involved in several functions by regulating the membrane potential and Ca²⁺ homeostasis in both excitable and non-excitable cells. This part of the review discusses the pharmacological modulation of TRPM4 by listing, comparing, and describing both endogenous and exogenous activators and inhibitors of the ion channel. Moreover, other strategies used to study TRPM4 functions are listed and described. These strategies include siRNA-mediated silencing of TRPM4, dominant-negative TRPM4 variants, and anti-TRPM4 antibodies. TRPM4 is receiving more and more attention and is likely to be the topic of research in the future.

Reactive Oxygen Species and Endothelial Ca2+ Signaling: Brothers in Arms or Partners in Crime?

An increase in intracellular Ca²⁺ concentration ([Ca²⁺]_i) controls virtually all endothelial cell functions and is, therefore, crucial to maintain cardiovascular homeostasis. An aberrant elevation in endothelial can indeed lead to severe cardiovascular disorders. Likewise, moderate amounts of reactive oxygen species (ROS) induce intracellular Ca²⁺ signals to regulate vascular functions, while excessive ROS production may exploit dysregulated Ca²⁺ dynamics to induce endothelial injury. Herein, we survey how ROS induce endothelial Ca²⁺ signals to regulate vascular functions and, vice versa, how aberrant ROS generation may exploit the Ca²⁺ handling machinery to promote endothelial dysfunction. ROS elicit endothelial Ca²⁺ signals by regulating inositol-1,4,5-trisphosphate receptors, sarco-endoplasmic reticulum Ca²⁺-ATPase 2B, two-pore channels, store-operated Ca²⁺ entry (SOCE), and multiple isoforms of transient receptor potential (TRP) channels. ROS-induced endothelial Ca²⁺ signals regulate endothelial permeability, angiogenesis, and generation of vasorelaxing mediators and can be exploited to induce therapeutic angiogenesis, rescue neurovascular coupling, and induce cancer regression. However, an increase in endothelial [Ca²⁺]_i induced by aberrant ROS formation may result in endothelial dysfunction, inflammatory diseases, metabolic disorders, and pulmonary artery hypertension. This information could pave the way to design alternative treatments to interfere with the life-threatening interconnection between endothelial ROS and Ca²⁺ signaling under multiple pathological conditions.

HBCD, TBECH, and BTBPE exhibit cytotoxic effects in human vascular endothelial cells by regulating mitochondria function and ROS production

Brominated flame retardants (BFRs), such as, 1,2,5,6-tetrabromocyclooctane (HBCD), 1,2-dibromo-4-(1,2-dibromopropyl)cyclohexane (TBECH), and 1 1,2-bis-(2,4,6-tribromophenoxy)ethane (BTBPE), have garnered increasing attention due to their potent biological effects. In the present study, the toxicity of HBCD, TBECH, and BTBPE in human vascular endothelial cells (ECs) was explored. The data showed that HBCD, TBECH, and BTBPE induced cytotoxicity, namely dose-dependent cell viability reduction, cell membrane permeability and apoptosis increase, migration, and lumen formation inhibition. Moreover, HBCD was found to be more toxic than BTBPE or TBECH. Exposure to HBCD, TBECH, and BTBPE led to the production of reactive oxygen species, mitochondrial superoxide generation, and mitochondrial membrane potential collapse, implying that reactive stress caused the cytotoxicity. The ATP content, glutathione content, superoxide dismutase, and MDA activities were reduced, indicating that mitochondrial dysfunction may be the key mechanisms responsible for apoptosis. The present study suggested that mitochondria are a new target of BFRs in ECs and further deepened our understanding of the developmental toxicity of BFRs.

Protective Effects of Baicalin on Arsenic Trioxide-induced Oxidative Damage and Apoptosis in Human Umbilical Vein Endothelial Cells

BACKGROUND/AIM

Arsenic trioxide (As₂O₃) is an environmental pollutant. However, the detailed mechanisms about As₂O₃-induced loss of endothelial integrity are unknown. This study aimed at investigating how As₂O₃ causes endothelial dysfunction and whether baicalin can reverse such dysfunction.

MATERIALS AND METHODS

Human umbilical vein endothelial cells (HUVECs) were used to examine As₂O₃-induced oxidative stress, and apoptosis. The influence of baicalin on As₂O₃-induced endothelial dysfunction were investigated.

RESULTS

The viability of HUVECs was inhibited by As₂O₃ and cells underwent apoptosis. As₂O₃ treatment increased NADPH oxidase activity, and elevated the level of reactive oxygen species (ROS). Formamidopyrimidine DNA-glycosylase- and endonuclease III-digestible adducts were accumulated. Baicalin reversed As₂O₃-induced apoptosis and As₂O₃-suppressed cell viability. Baicalin caused a decrease in NADPH oxidase activity, and re-balanced the ROS level. As₂O₃-induced formamidopyrimidine DNA-glycosylase- and endonuclease III-digestible adducts were down-regulated.

CONCLUSION

Baicalin was found to have the potential capacity to protect endothelial cells from As₂O₃-induced cytotoxicity.

Counteracting arsenic toxicity: Curcumin to the rescue?

Arsenicosis leads to various irreversible damages in several organs and is considered to be a carcinogen. The effects of chronic arsenic poisoning are a result of an imbalance between pro- and antioxidant homeostasis, oxidative stress, as well as DNA and protein damage. Curcumin, the polyphenolic pigment extracted from the rhizome of Curcuma longa, is well-known for its pleiotropic medicinal effects. Curcumin has been shown to have ameliorative effects in arsenic-induced genotoxicity, nephrotoxicity, hepatotoxicity, angiogenesis, skin diseases, reproductive toxicity, neurotoxicity, and immunotoxicity. This review aims to summarize the scientific evidence on arsenic toxicity in various organs and the ameliorative effects of curcumin on the arsenic toxicity.

TRPM4 non-selective cation channel in human atrial fibroblast growth

Cardiac fibroblasts play an important role in cardiac matrix turnover and are involved in cardiac fibrosis development. Ca²⁺ is a driving belt in this phenomenon. This study evaluates the functional expression and contribution of the Ca²⁺-activated channel TRPM4 in atrial fibroblast phenotype. Molecular and electrophysiological investigations were conducted in human atrial fibroblasts in primary culture and in atrial fibroblasts obtained from wild-type and transgenic mice with disrupted Trpm4 gene (Trpm4^-/-). A typical TRPM4 current was recorded on human cells (equal selectivity for Na⁺ and K⁺, activation by internal Ca²⁺, voltage sensitivity, conductance of 23.2 pS, inhibition by 9-phenanthrol (IC₅₀ = 6.1 × 10^-6 mol L^-1)). Its detection rate was 13% on patches at days 2-4 in culture but raised to 100% on patches at day 28. By the same time, a cell growth was observed. This growth was smaller when cells were maintained in the presence of 9-phenanthrol. Similar cell growth was measured on wild-type mice atrial fibroblasts during culture. However, this growth was minimized on Trpm4^-/- mice fibroblasts compared to control animals. In addition, the expression of alpha smooth muscle actin increased during culture of atrial fibroblasts from wild-type mice. This was not observed in Trpm4^-/- mice fibroblasts. It is concluded that TRPM4 participates in fibroblast growth and could thus be involved in cardiac fibrosis.