Efflux inhibition by H2S confers sensitivity to doxorubicin-induced cell death in liver cancer cells

The association of ABC proteins with multidrug resistance in cancer

Multidrug resistance (MDR) poses one of the primary challenges for cancer treatment, especially in cases of metastatic disease. Various mechanisms contribute to MDR, including the overexpression of ATP-binding cassette (ABC) proteins. In this context, we reviewed the literature to establish a correlation between the overexpression of ABC proteins and MDR in cancer, considering both in vitro and clinical studies. Initially, we presented an overview of the seven subfamilies of ABC proteins, along with the subcellular localization of each protein. Subsequently, we identified a panel of 20 ABC proteins (ABCA1-3, ABCA7, ABCB1-2, ABCB4-6, ABCC1-5, ABCC10-11, ABCE1, ABCF2, ABCG1, and ABCG2) associated with MDR. We also emphasize the significance of drug sequestration by certain ABC proteins into intracellular compartments. Among the anticancer drugs linked to MDR, 29 were definitively identified as substrates for at least one of the three most crucial ABC transporters: ABCB1, ABCC1, and ABCG2. We further discussed that the most commonly used drugs in standard regimens for mainly breast cancer, lung cancer, and acute lymphoblastic leukemia could be subject to MDR mediated by ABC transporters. Collectively, these insights will aid in conducting new studies aimed at a deeper understanding of the clinical MDR mediated by ABC proteins and in designing more effective pharmacological treatments to enhance the objective response rate in cancer patients.

The role of cystathionine β-synthase in cancer

Cystathionine β-synthase (CBS) occupies a key position as the initiating and rate-limiting enzyme in the sulfur transfer pathway and plays a vital role in health and disease. CBS is responsible for regulating the metabolism of cysteine, the precursor of glutathione (GSH), an important antioxidant in the body. Additionally, CBS is one of the three enzymes that produce hydrogen sulfide (H2S) in mammals through a variety of mechanisms. The dysregulation of CBS expression in cancer cells affects H2S production through direct or indirect pathways, thereby influencing cancer growth and metastasis by inducing angiogenesis, facilitating proliferation, migration, and invasion, modulating cellular energy metabolism, promoting cell cycle progression, and inhibiting apoptosis. It is noteworthy that CBS expression exhibits complex changes in different cancer models. In this paper, we focus on the CBS synthesis and metabolism, tissue distribution, potential mechanisms influencing tumor growth, and relevant signaling pathways. We also discuss the impact of pharmacological CBS inhibitors and silencing CBS in preclinical cancer models, supporting their potential as targeted cancer therapies.

Hydrogen Sulfide and Liver Health: Insights into Liver Diseases

Significance: Hydrogen sulfide (H2S) is a recently recognized gasotransmitter involved in physiological and pathological conditions in mammals. It protects organs from oxidative stress, inflammation, hypertension, and cell death. With abundant expression of H2S-production enzymes, the liver is closely linked to H2S signaling. Recent Advances: Hepatic H2S comes from various sources, including gut microbiota, exogenous sulfur salts, and endogenous production. Recent studies highlight the importance of hepatic H2S in liver diseases such as nonalcoholic fatty liver disease (NAFLD), liver injury, and cancer, particularly at advanced stages. Endogenous H2S production deficiency is associated with severe liver disease, while exogenous H2S donors protect against liver dysfunction. Critical Issues: However, the roles of H2S in NAFLD, liver injury, and liver cancer are still debated, and its effects depend on donor type, dosage, treatment duration, and cell type, suggesting a multifaceted role. This review aimed to critically evaluate H2S production, metabolism, mode of action, and roles in liver function and disease. Future Direction: Understanding H2S's precise roles and mechanisms in liver health will advance potential therapeutic applications in preclinical and clinical research. Targeting H2S-producing enzymes and exogenous H2S sources, alone or in combination with other drugs, could be explored. Quantifying endogenous H2S levels may aid in diagnosing and managing liver diseases. Antioxid. Redox Signal. 40, 122-144.

Protein Persulfidation: Recent Progress and Future Directions

Significance: Hydrogen sulfide (H2S) is considered to be a gasotransmitter along with carbon monoxide (CO) and nitric oxide (NO), and is known as a key regulator of physiological and pathological activities. S-sulfhydration (also known as persulfidation), a mechanism involving the formation of protein persulfides by modification of cysteine residues, is proposed here to explain the multiple biological functions of H2S. Investigating the properties of protein persulfides can provide a foundation for further understanding of the potential functions of H2S. Recent Advances: Multiple methods have been developed to determine the level of protein persulfides. It has been demonstrated that protein persulfidation is involved in many biological processes through various mechanisms including the regulation of ion channels, enzymes, and transcription factors, as well as influencing protein-protein interactions. Critical Issues: Some technical and theoretical questions remain to be solved. These include how to improve the specificity of the detection methods for protein persulfidation, why persulfidation typically occurs on one or a few thiols within a protein, how this modification alters protein functions, and whether protein persulfidation has organ-specific patterns. Future Directions: Optimizing the detection methods and elucidating the properties and molecular functions of protein persulfidation would be beneficial for current therapeutics. In this review, we introduce the detailed mechanism of the persulfidation process and discuss persulfidation detection methods. In addition, this review summarizes recent discoveries of the selectivity of protein persulfidation and the regulation of protein functions and cell signaling pathways by persulfidation. Antioxid. Redox Signal. 39, 829-852.

The double-edged sword role of hydrogen sulfide in hepatocellular carcinoma

With an increasing worldwide prevalence, hepatocellular carcinoma (HCC) is the most common primary malignant tumor of the liver in the world. It is also the primary reason for cancer-related death in the world. The pathogenesis of HCC is complex, such as DNA methylation changes, immune regulatory disorders, cell cycle disorders, chromosomal instability, and so on. Although many studies have been conducted on HCC, the molecular mechanisms of HCC are not completely understood. At present, there is no effective treatment for HCC. Hydrogen sulfide (H2S) has long been regarded as a toxic gas with the smell of rotten eggs, but recent studies have shown that it is an important gasotransmitter along with carbon monoxide (CO) and nitric oxide (NO). Increasing evidence indicates that H2S has multiple biological functions, such as anti-inflammation, anti-apoptosis, anti-oxidative stress, and so on. Recently, a lot of evidence has shown that H2S has a "double-edged sword" effect in HCC, but the mechanism is not fully understood. Here, we reviewed the progress on the role and mechanism of H2S in HCC in recent years, hoping to provide a theoretical reference for future related research.

Smart Nanoplatform for Visualizing Hydrogen Sulfide and Amplifying Oxidative Stress to Tumor Apoptosis

Oxidative stress is involved in various signaling pathways and serves a key role in inducing cell apoptosis. Therefore, it is significant to monitor oxidative stress upon drug release for the assessment of therapeutic effects in cancer cells. Herein, a glutathione (GSH)-responsive surface-enhanced Raman scattering (SERS) nanoplatform is proposed for ultra-sensitively monitoring the substance related with oxidative stress (hydrogen sulfide, H2S), depleting reactive sulfur species and releasing anticancer drugs to amplify oxidative stress for tumor apoptosis. The Au@Raman reporter@Ag (Au@M@Ag) nanoparticles, where a 4-mercaptobenzonitrile molecule as a Raman reporter was embedded between layers of gold and silver to obtain sensitive SERS response, were coated with a covalent organic framework (COF) shell to form a core-shell structure (Au@M@Ag@COFs) as the SERS nanoplatform. The COF shell loading doxorubicin (DOX) of Au@M@Ag@COFs exhibited the GSH-responsive degradation capacity to release DOX, and its Ag layer as the sensing agent was oxidized to Ag2S by H2S to result in its prominent changes in SERS signals with a low detection limit of 0.33 nM. Moreover, the releasing DOX can inhibit the generation of H2S to promote the production of reactive oxygen species, and the depletion of reactive sulfur species (GSH and H2S) in cancer cells can further enhance the oxidative stress to induce tumor apoptosis. Overall, the SERS strategy could provide a powerful tool to monitor the dynamic changes of oxidative stress during therapeutic processes in a tumor microenvironment.

Cystathionine gamma-lyase/H2 S signaling facilitates myogenesis under aging and injury condition

Hydrogen sulfide (H₂ S) can be endogenously produced and belongs to the class of signaling molecules known as gasotransmitters. Cystathionine gamma-lyase (CSE)-derived H₂ S is implicated in the regulation of cell differentiation and the aging process, but the involvements of the CSE/H₂ S system in myogenesis upon aging and injury have not been explored. In this study, we demonstrated that CSE acts as a major H₂ S-generating enzyme in skeletal muscles and is significantly down-regulated in aged skeletal muscles in mice. CSE deficiency exacerbated the age-dependent sarcopenia and cardiotoxin-induced injury/regeneration in mouse skeletal muscle, possibly attributed to inefficient myogenesis. In contrast, supplement of NaHS (an H₂ S donor) induced the expressions of myogenic genes and promoted muscle regeneration in mice. In vitro, incubation of myoblast cells (C2C12) with H₂ S promoted myogenesis, as evidenced by the inhibition of cell cycle progression and migration, altered expressions of myogenic markers, elongation of myoblasts, and formation of multinucleated myotubes. Myogenesis was also found to upregulate CSE expression, while blockage of CSE/H₂ S signaling resulted in a suppression of myogenesis. Mechanically, H₂ S significantly induced the heterodimer formation between MEF2c and MRF4 and promoted the binding of MEF2c/MRF4 to myogenin promoter. MEF2c was S-sulfhydrated at both cysteine 361 and 420 in the C-terminal transactivation domain, and blockage of MEF2c S-sulfhydration abolished the stimulatory role of H₂ S on MEF2c/MRF4 heterodimer formation. These findings support an essential role for H₂ S in maintaining myogenesis, presenting it as a potential candidate for the prevention of age-related sarcopenia and treatment of muscle injury.

The interaction of disulfiram and H2S metabolism in inhibition of aldehyde dehydrogenase activity and liver cancer cell growth

Disulfiram (DSF), a sulfur-containing compound, has been used to treat chronic alcoholism and cancer for decades by inactivating aldehyde dehydrogenase (ALDH). Hydrogen sulfide (H₂S) is a new gasotransmitter and regulates various cellular functions by S-sulfhydrating cysteine in the target proteins. H₂S exhibits similar properties to DSF in the sensitization of cancer cells. The interaction of DSF and H₂S on ALDH activity and liver cancer cell survival are not clear. Here it was demonstrated that DSF facilitated H₂S release from thiol-containing compounds, and DSF and H₂S were both capable of regulating ALDH through inhibition of gene expression and enzymatic activity. The supplement of H₂S sensitized human liver cancer cells (HepG2) to DSF-inhibited cell viability. The expression of cystathionine gamma-lyase (a major H₂S-generating enzyme) was lower but ALDH was higher in mouse liver cancer stem cells (Dt81Hepa1-6) in comparison with their parental cells (Hepa1-6), and H₂S was able to inhibit liver cancer stem cell adhesion. In conclusion, these data point to the potential of combining DSF and H₂S for inhibition of cancer cell growth and tumor development by targeting ALDH.

Cysteine metabolic circuitries: druggable targets in cancer

To enable survival in adverse conditions, cancer cells undergo global metabolic adaptations. The amino acid cysteine actively contributes to cancer metabolic remodelling on three different levels: first, in its free form, in redox control, as a component of the antioxidant glutathione or its involvement in protein s-cysteinylation, a reversible post-translational modification; second, as a substrate for the production of hydrogen sulphide (H2S), which feeds the mitochondrial electron transfer chain and mediates per-sulphidation of ATPase and glycolytic enzymes, thereby stimulating cellular bioenergetics; and, finally, as a carbon source for epigenetic regulation, biomass production and energy production. This review will provide a systematic portrayal of the role of cysteine in cancer biology as a source of carbon and sulphur atoms, the pivotal role of cysteine in different metabolic pathways and the importance of H2S as an energetic substrate and signalling molecule. The different pools of cysteine in the cell and within the body, and their putative use as prognostic cancer markers will be also addressed. Finally, we will discuss the pharmacological means and potential of targeting cysteine metabolism for the treatment of cancer.

Transcriptional regulation of alcohol induced liver fibrosis in a translational porcine hepatocellular carcinoma model

Hepatocellular carcinoma (HCC) is the 5th most common and 2nd deadliest cancer worldwide. HCC risk factors include alcohol induced liver cirrhosis, which prompts hepatic inflammation, cell necrosis, and fibrosis deposition. As 25% of HCC cases are associated with alcohol induced liver disease, understanding the effects of the cirrhotic liver microenvironment on HCC tumor biology and therapeutic responses are critical. This study utilized the Oncopig Cancer Model-a transgenic pig model that recapitulates human HCC through induced expression of KRAS^G12D and TP53^R167H driver mutations-to investigate the molecular mechanisms underlying alcohol induced liver disease. Oncopigs (n = 5) underwent fibrosis induction via infusion of ethanol and ethiodized oil (1:3 v/v dosed at 0.75 mL/kg) into the hepatic arterial circulation. Eight-weeks post induction, liver tissue samples from fibrotic and age-matched control (n = 5) Oncopigs were collected for histological evaluation and transcriptional profiling. Increased hepatic inflammation and fibrosis was observed in fibrotic Oncopigs via pathological assessment. Transcriptional profiling (RNA-seq) resulted in the identification of 4387 differentially expressed genes between Oncopig fibrotic and control livers. GO term enrichment analysis identified pathway alterations associated with cirrhosis progression in humans, including cell proliferation, angiogenesis, extracellular matrix deposition, and oxidation-reduction. Key alterations include activation of hepatic stellate cells, increased matrix metalloproteinase production, and altered expression of ABC and SLC transporter genes involved in transport of anticancer drugs.These results demonstrate Oncopig liver fibrosis recapitulates transcriptional hallmarks of human cirrhosis, making the Oncopig an ideal model for studying the effects of the cirrhotic liver microenvironment on HCC tumor biology and therapeutic response.

S-Persulfidation: Chemistry, Chemical Biology, and Significance in Health and Disease

Significance: S-Persulfidation generates persulfide adducts (RSSH) on both small molecules and proteins. This process is believed to be critical in the regulation of biological functions of reactive sulfur species such as H₂S, as well as in signal transduction. S-Persulfidation also plays regulatory roles in human health and diseases. Recent Advances: Some mechanisms underlying the generation of low-molecular-weight persulfides and protein S-persulfidation in living organisms have been uncovered. Some methods for the specific delivery of persulfides and the detection of persulfides in biological systems have been developed. These advances help to pave the road to better understand the functions of S-persulfidation. Critical Issues: Persulfides are highly reactive and unstable. Currently, their identification relies on trapping them by S-alkylation, but this is not always reliable due to rapid sulfur exchange reactions. Therefore, the presence, identity, and fates of persulfides in biological environments are sometimes difficult to track. Future Directions: Further understanding the fundamental chemistry/biochemistry of persulfides and development of more reliable detection methods are needed. S-Persulfidation in specific protein targets is essential in organismal physiological health and human disease states. Besides cardiovascular and neuronal systems, the roles of persulfidation in other systems need to be further explored. Contradictory results of persulfidation in biology, especially in cancer, need to be clarified.

The multifaceted roles of sulfane sulfur species in cancer-associated processes

Sulfane sulfur species comprise a variety of biologically relevant hydrogen sulfide (H₂S)-derived species, including per- and poly-sulfidated low molecular weight compounds and proteins. A growing body of evidence suggests that H₂S, currently recognized as a key signaling molecule in human physiology and pathophysiology, plays an important role in cancer biology by modulating cell bioenergetics and contributing to metabolic reprogramming. This is accomplished through functional modulation of target proteins via H₂S binding to heme iron centers or H₂S-mediated reversible per- or poly-sulfidation of specific cysteine residues. Since sulfane sulfur species are increasingly viewed not only as a major source of H₂S but also as key mediators of some of the biological effects commonly attributed to H₂S, the multifaceted role of these species in cancer biology is reviewed here with reference to H₂S, focusing on their metabolism, signaling function, impact on cell bioenergetics and anti-tumoral properties.

Inhibition of endogenous hydrogen sulfide biosynthesis enhances the anti-cancer effect of 3,3'-diindolylmethane in human gastric cancer cells

AIMS

3,3'-Diindolylmethane (DIM) has limited anti-cancer effects in gastric cancer. Hydrogen sulfide (H₂S) plays an important role in the tumor development and therapy, cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE), two key endogenous H₂S biosynthesis enzymes, can affect endogenous H₂S levels and alter cancer treatment. Our main objective was to investigate whether the aminooxyacetic acid (AOAA) and DL-Propargylglycine (PAG), two specific inhibitors of CBS and CSE, could assist DIM to exert a stronger anti-cancer effects in gastric cancer BGC-823 and SGC-7901 cells.

MATERIALS AND METHODS

Cell proliferation was assayed by MTT and cell colony-forming assay. Apoptosis and migration were detected by Hoechst staining and scratch test respectively. Western blot was used to evaluate the expression of proteins related to proliferation, apoptosis and migration.

KEY FINDINGS

Combination of AOAA or PAG with DIM synergistically inhibited proliferation and migration, increased apoptosis in gastric cancer cells. The p38-p53 axis was also further activated by the combination of AOAA or PAG with DIM. Exogenous H₂S from sodium hydrosulfide, attenuated the efficacy of DIM in cancer cells by reducing the activation level of p38-p53 axis. Taken together, AOAA or PAG inhibited the expression of endogenous H₂S biosynthesis enzymes and effectively enhanced susceptibility of gastric cancer to DIM through activating p38-p53 axis.

SIGNIFICANCE

The current study highlight more precise requirements for the clinical application of sulfur-containing anti-cancer drugs, and open a new way to enhance the sensitivity of DIM in chemotherapy of gastric cancer.

Hydrogen sulfide signaling in regulation of cell behaviors

Recent advances in the biomedical importance of H₂S have help us understand various cellular functions and pathophysiological processes from a new aspect. Specially, H₂S has been demonstrated to play multiple roles in regulating cell behaviors, including cell survival, cell differentiation, cell senescence, cell hypertrophy, cell atrophy, cell metaplasia, and cell death, etc. H₂S contributes to cell behavior changes via various mechanisms, such as histone modification, DNA methylation, non-coding RNA changes, DNA damage repair, transcription factor activity, and post-translational modification of proteins by S-sulfhydration, etc. In this review, we summarized the recent research progress on H₂S signaling in control of cell behaviors and discussed the ways of H₂S regulation of gene expressions. Given the key roles of H₂S in both health and diseases, a better understanding of the regulation of H₂S on cell behavior change and the underlying molecular mechanisms will help us to develop novel and more effective strategies for clinical therapy.

Cystathionine gamma-lyase/H2S system suppresses hepatic acetyl-CoA accumulation and nonalcoholic fatty liver disease in mice

AIMS

Hydrogen sulfide (H₂S) as a novel gasotransmitter can be endogenously produced in liver by cystathionine gamma-lyase (CSE). The dysfunctions of CSE/H₂S system have been linked to various liver diseases. Acetyl-CoA is the key intermediate from the metabolism of lipid. This study examined the roles of H₂S in hepatic acetyl-CoA and lipid metabolism.

MATERIALS AND METHODS

Both in vitro cell model and in vivo animal model of lipid accumulation were used in this study. Western blotting and real-time PCR were used for analysis of protein and mRNA expression. Acetyl-CoA was analyzed by a coupled enzyme assay, and lipid accumulation was observed with Oil Red O staining.

KEY FINDINGS

Incubation of human liver carcinoma (HepG2) cells with a mixture of free fatty acids (FFAs) or high glucose reduced CSE expression and H₂S production, promoted intracellular accumulation of acetyl-CoA and lipid. Supply of exogenous NaHS or cysteine reduced acetyl-CoA contents and lipid accumulation, while blockage of CSE activity promoted intracellular lipid accumulation. Furthermore, H₂S blocked FFAs-induced transcriptions of de novo lipogenesis, inflammation, and fibrosis-related genes. In vivo, knockout of CSE gene stimulated more hepatic acetyl-CoA and lipid accumulation in mice induced by high-fat choline-deficient diet. The expressions of lipogenesis, inflammation, and fibrosis-related genes were significantly higher in liver tissues from CSE knockout mice when compared with wild-type mice.

SIGNIFICANCE

CSE/H₂S system is indispensable for maintaining the homeostasis of acetyl-CoA and lipid accumulation and protecting from the development of inflammation and fibrosis in liver under excessive caloric ingestion.

Golgi Stress Response, Hydrogen Sulfide Metabolism, and Intracellular Calcium Homeostasis

Aims: The physiological and pathological importance of hydrogen sulfide (H₂S) as a novel gasotransmitter has been widely recognized. Cystathionine gamma-lyase (CSE) is one of the major H₂S-producing enzymes and it regulates diverse functions in connection with intracellular calcium (Ca²⁺). The aim of this study is to examine the role of H₂S in Golgi stress-related cell injury and skeletal muscle disorders. Results: Golgi stressors (brefeldin A [BFA] and monensin) decreased the expression of GM130 and ATP2C1 (two markers of Golgi stress response), induced Golgi apparatus fragmentation, and caused a higher level of oxidative stress and cell apoptosis in mouse myoblast cells. In addition, Golgi stressors upregulated CSE expression and endogenous H₂S generation, and exogenously applied H₂S was able to protect but inhibition of CSE/H₂S system deteriorated Golgi stress response. Activating transcription factor 4 (ATF4) acted as an upstream molecule to increase CSE expression on Golgi stress response. Mechanically, Golgi stressors induced intracellular level of Ca²⁺, and chelating cellular Ca²⁺ markedly attenuated Golgi stress response, indicating the key role of Ca²⁺ in initiating Golgi stress and cell apoptosis. Further, administration of either angiotensin II or BFA initiated Golgi stress response and induced skeletal muscle atrophy in mice, which was further deteriorated by CSE deficiency but rescued by exogenously applied sodium hydrosulfide (NaHS). Innovation and Conclusion: The activation of the CSE/H₂S pathway and the decrease of intracellular Ca²⁺ are two cellular protective mechanisms against Golgi stress, and the CSE/H₂S system would be a target for preventing skeletal muscle dysfunctions.

Hydrogen Sulfide Metabolism and Signaling in the Tumor Microenvironment

Hydrogen sulfide (H2S), while historically perceived merely as a toxicant, has progressively emerged as a key regulator of numerous processes in mammalian physiology, exerting its signaling function essentially through interaction with and/or modification of proteins, targeting mainly cysteine residues and metal centers. As a gaseous signaling molecule that freely diffuses across aqueous and hydrophobic biological milieu, it has been designated the third 'gasotransmitter' in mammalian physiology. H2S is synthesized and detoxified by specialized endogenous enzymes that operate under a tight regulation, ensuring homeostatic levels of this otherwise toxic molecule. Indeed, imbalances in H2S levels associated with dysfunctional H2S metabolism have been growingly correlated with various human pathologies, from cardiovascular and neurodegenerative diseases to cancer. Several cancer cell lines and specimens have been shown to naturally overexpress one or more of the H2S-synthesizing enzymes. The resulting increased H2S levels have been proposed to promote cancer development through the regulation of various cancer-related processes, which led to the interest in pharmacological targeting of H2S metabolism. Herein are summarized some of the key observations that place H2S metabolism and signaling pathways at the forefront of the cellular mechanisms that support the establishment and development of a tumor within its complex and challenging microenvironment. Special emphasis is given to the mechanisms whereby H2S helps shaping cancer cell bioenergetic metabolism and affords resistance and adaptive mechanisms to hypoxia.

Screening of Molecular Targets of Action of Atractylodin in Cholangiocarcinoma by Applying Proteomic and Metabolomic Approaches

Cholangiocarcinoma (CCA) is cancer of the bile duct and the highest incidence of CCA in the world is reported in Thailand. Our previous in vitro and in vivo studies identified Atractylodes lancea (Thunb) D.C. as a promising candidate for CCA treatment. The present study aimed to examine the molecular targets of action of atractylodin, the bioactive compound isolated from A. lancea, in CCA cell line by applying proteomic and metabolomic approaches. Intra- and extracellular proteins and metabolites were identified by LC-MS/MS following exposure of CL-6, the CCA cell line, to atractylodin for 24 and 48 h. Analysis of the protein functions and pathways involved was performed using a Venn diagram, PANTHER, and STITCH software. Analysis of the metabolite functions and pathways involved, including the correlation between proteins and metabolites identified was performed using MetaboAnalyst software. Results suggested the involvement of atractylodin in various cell biology processes. These include the cell cycle, apoptosis, DNA repair, immune response regulation, wound healing, blood vessel development, pyrimidine metabolism, the citrate cycle, purine metabolism, arginine and proline metabolism, glyoxylate and dicarboxylate metabolism, the pentose phosphate pathway, and fatty acid biosynthesis. Therefore, it was proposed that the action of atractylodin may involve the destruction of the DNA of cancer cells, leading to cell cycle arrest and cell apoptosis.

Induction of cystathionine gamma-lyase expression and metallothionein-1 S-sulfhydration alleviate cadmium-induced cell death in myoblast cells

Hydrogen sulfide (H₂S), a multifunctional gasotransmitter, participates in a wide range of cellular signal transduction and pathophysiological processes. Cystathionine gamma-lyase (CSE) acts as a major H₂S-generating enzyme in peripheral organs and tissues. As a cysteine-rich and heavy metal-binding protein, metallothionein-1 (MT-1) is known to protect cells from various environmental stresses. Here we demonstrated that exposure of cadmium (Cd) induced oxidative stress, depleted intracellular thiols, and stimulated apoptotic cell death in mouse myoblast cells. CSE expression and H₂S production were significantly enhanced by Cd treatment. NaHS, a well-known H₂S donor, at physiologically relevant concentration significantly alleviated Cd-induced damage in both myoblasts and mouse skeletal muscles. In contrast, down-regulation of CSE/H₂S system deteriorated Cd-stimulated oxidative stress and cell death. Exposure of the cells to Cd lead to increased expressions of metal regulatory transcription factor 1 and MT-1, while siRNA-mediated MT-1 knockdown alleviated Cd-induced CSE expression and caused more oxidative stress and cell death. In addition, H₂S post-translationally modified MT-1 by S-sulfhydration and stabilized zinc-protein complex. Taken together, these data suggest that CSE/H₂S system would protect myoblasts and skeletal muscles from Cd-induced damage by S-sufhydrating MT-1.