Down-regulation Of Heme Oxygenase-1 Research Articles

Heme oxygenase 1 linked to inactivation of subchondral osteoclasts in osteoarthritis.

Osteoarthritis (OA) is a chronic progressive osteoarthropathy in the elderly. Osteoclast activation plays a crucial role in the occurrence of subchondral bone loss in early OA. However, the specific mechanism of osteoclast differentiation in OA remains unclear. In our study, gene expression profiles related to OA disease progression and osteoclast activation were screened from the Gene Expression Omnibus (GEO) repository. GEO2R and Funrich analysis tools were employed to find differentially expressed genes (DEGs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses demonstrated that chemical carcinogenesis, reactive oxygen species (ROS), and response to oxidative stress were mainly involved in osteoclast differentiation in OA subchondral bone. Furthermore, fourteen DEGs that are associated with oxidative stress were identified. The first ranked differential gene, heme oxygenase 1 (HMOX1), was selected for further validation. Related results showed that osteoclast activation in the pathogenesis of OA subchondral bone is accompanied by the downregulation of HMOX1. Carnosol was revealed to inhibit osteoclastogenesis by targeting HMOX1 and upregulating the expression of antioxidant protein in vitro. Meanwhile, carnosol was found to alleviate the severity of OA by inhibiting the activation of subchondral osteoclasts in vivo. Our research indicated that the activation of osteoclasts due to subchondral bone redox dysplasia may serve as a significant pathway for the advancement of OA. Targeting HMOX1 in subchondral osteoclasts may offer novel insights for the treatment of early OA.

Mechanism of Fat Mass and Obesity-Related Gene-Mediated Heme Oxygenase-1 m6A Modification in the Recovery of Neurological Function in Mice with Spinal Cord Injury.

This study examined the mechanism of fat mass and obesity-related gene (FTO)-mediated heme oxygenase-1 (HO-1) m6A modification facilitating neurological recovery in spinal cord injury (SCI) mice. FTO/HO-1 was identified as a key regulator of SCI as well as a potential target for treatment of SCI. An SCI mouse was treated with pcDNA3.1-FTO/pcDNA3.1-NC/Dac51. An oxygen/glucose deprivation (OGD) cell model simulated SCI, with cells treated with pcDNA3.1-FTO/si-HO-1/Dac51. Motor function and neurobehavioral evaluation were assessed using the Basso, Beattie, and Bresnahan (BBB) scale and modified neurological severity score (mNSS). Spinal cord pathology and neuronal apoptosis were assessed. Further, FTO/HO-1 mRNA and protein levels, HO-1 mRNA stability, the interaction of YTHDF2 with HO-1 mRNA, neuronal viability/apoptosis, and HO-1 m6A modification were evaluated. Spinal cord injury mice exhibited reduced BBB, elevated mNSS scores, disorganized spinal cord cells, scattered nuclei, and severe nucleus pyknosis. pcDNA3.1-FTO elevated FTO mRNA, protein expression, and BBB score; reduced the mNSS score of SCI mice; decreased neuronal apoptosis; improvedthe cell arrangement; and improved nucleus pyknosis in spinal cord tissues. OGD decreased FTO expression. FTO upregulation ameliorated OGD-induced neuronal apoptosis. pcDNA3.1-FTO reduced HO-1 mRNA and protein and HO-1 m6A modification, while increasing HO-1 mRNA stability and FTO in OGD-treated cells. FTO upregulated HO-1 by modulating m6A modification. HO-1 downregulation attenuated the effect of FTO. pcDNA3.1-FTO/Dac51 increased the HO-1 m6A level in mouse spinal cord tissue homogenate, reduced BBB, boosted mNSS scores of SCI mice, aggravated nucleus pyknosis, and increased neuronal apoptosis in spinal cord tissues, confirming that FTO mediated HO-1 m6A modification facilitated neurological recovery in SCI mice. The fat mass and obesity-related gene modulates HO-1 mRNA stability by regulating m6A modification levels, thereby influencing HO-1 expression and promoting neurological recovery in SCI mice.

α-Pyrrolidinononanophenone derivatives induce differentiated SH-SY5Y neuroblastoma cell apoptosis via reduction of antioxidant capacity: Involvement of NO depletion and inactivation of Nrf2/HO1 signaling pathway

α-Pyrrolidinononanophenone (α-PNP) derivatives are known to be one of the hazardous new psychoactive substances due to the most extended hydrocarbon chains of any pyrrolidinophenones on the illicit drug market. Our previous report showed that 4'-iodo-α-PNP (I-α-PNP) is the most potent cytotoxic compound among α-PNP derivatives and induces apoptosis due to mitochondrial dysfunction and suppression of nitric oxide (NO) production in differentiated human neuronal SH-SY5Y cells. In this study, to clarify the detailed action mechanisms by I-α-PNP, we investigated the mechanism of reactive oxygen species (ROS) -dependent apoptosis by I-α-PNP in differentiated SH-SY5Y with a focus on the antioxidant activities. Treatment with I-α-PNP elicits overproduction of ROS such as H2O2, hydroxyl radical, and 4-hydroxy-2-nonenal, and pretreatment with antioxidant N-acetyl-L-cysteine is attenuated the SH-SY5Y cells apoptosis by I-α-PNP. These results suggested that the overproduction of ROS is related to SH-SY5Y cell apoptosis by I-α-PNP. In addition, I-α-PNP markedly decreased antioxidant capacity in differentiated cells than in undifferentiated cells and inhibited the upregulation of hemeoxygenase 1 (HO1) and glutathione peroxidase 4 (GPX4) expression caused by induction of differentiation. Furthermore, the treatment with I-α-PNP increased the nuclear expression level of BTB Domain And CNC Homolog 1 (Bach1), a transcriptional repressor of Nrf2, only in differentiated cells, suggesting that the marked decrease in antioxidant capacity in differentiated cells was due to suppression of Nrf2/HO1 signaling by Bach1. Additionally, pretreatment with an NO donor suppresses the I-α-PNP-evoked ROS overproduction, HO1 down-regulation, increased nuclear Bach1 expression and reduced antioxidant activity in the differentiated cells. These findings suggest that the ROS-dependent apoptosis by I-α-PNP in differentiated cells is attributed to the inactivation of the Nrf2/HO1 signaling pathway triggered by NO depletion.

Abstract P1156: Potential Role Of Ferroptosis In Duchenne Muscular Dystrophy-associated Cardiomyopathy

Background and Aims: Duchenne muscular dystrophy (DMD) is the most common and fatal form of muscular dystrophy. DMD-associated cardiomyopathy (DMD-CM) is a major cause of morbidity and mortality in patients with DMD. Ferroptosis, a new type of regulated cell death characterized by iron-dependence and the accumulation of cell membrane lipid peroxidation, has been manifested in various cardiovascular disease conditions. However, ferroptosis has not been studied in DMD-CM. Here, we aim to determine whether ferroptosis play a potential role in DMD-CM. Methods and Results: We used a dystrophin/utrophin double knockout (mdx:utr -/- ) mouse model that displays clinical signs of DMD and DMD-CM. We performed RNA isolation from the ventricles of 3-month-old wild type (WT) and mdx:utr -/- mice (n=3) and performed RNA-Seq analysis. We found alterations of ferroptosis-related pathways such as GTP cyclohydrolase 1, transferrin receptor, glutamine transporter SLC38A1, heme oxygenase-1 (HMOX-1), and arachidonate 5-lipoxygenase (ALOX5) pathways in mdx:utr -/- hearts compared to WT hearts. Western blots confirmed the upregulation of ALOX5 and downregulation of HMOX-1, ferroptosis suppressor protein 1, and NADPH oxidase 4 in mdx:utr -/- hearts, while there was no change in glutathione peroxidase 4 (GPX4) levels. We also observed an increased level of lipid peroxidation in mdx:utr -/- hearts compared to WT as estimated by the level of malondialdehyde. Live/dead viability assays demonstrated a higher cell death rate in cardiomyocytes from mdx:utr -/- mice (53.7±7.2%, n=24) compared to those from WT mice (11.7±1.1%, n=17, p< 0.01) under control conditions. The observed cell death in mdx:utr -/- cardiomyocytes was efficiently prevented by the selective ferroptosis inhibitor ferrostatin-1 (10 μM) (7.4±1.5%, n=9, p<0.01), but not by the apoptosis inhibitor emricasan (20 μM) (56.0±1.6%, n=3, NS). Similarly, higher death rates were also observed in mdx:utr -/- than in WT cardiomyocytes when they were treated with various ferroptosis inducers such as iron overload and the GPX4 inhibitor RSL3. Conclusion: We have deciphered the link between ferroptosis and DMD-CM for the first time. Our data suggest novel targets for the treatment of DMD-CM by inhibiting ferroptosis.

Veronica persica Ethanol Extract Ameliorates Dinitrochlorobenzene-Induced Atopic Dermatitis-like Skin Inflammation in Mice, Likely by Inducing Nrf2/HO-1 Signaling.

Atopic dermatitis (AD) is chronic allergic contact dermatitis with immune dysregulation. Veronica persica has pharmacological activity that prevents asthmatic inflammation by ameliorating inflammatory cell activation. However, the potential effects of the ethanol extract of V. persica (EEVP) on AD remain elusive. This study evaluated the activity and underlying molecular pathway of EEVP in two AD models: dinitrochlorobenzene (DNCB)-induced mice and interferon (IFN)-γ/tumor necrosis factor (TNF)-α-stimulated human HaCaT keratinocytes. EEVP attenuated the DNCB-induced increase in serum immunoglobulin E and histamine levels, mast cell counts in toluidine-blue-stained dorsal skin, inflammatory cytokine (IFN-γ, interleukin [IL]-4, IL-5, and IL-13) levels in cultured splenocytes, and the mRNA expression of IL6, IL13, IL31 receptor, CCR-3, and TNFα in dorsal tissue. Additionally, EEVP inhibited the IFN-γ/TNF-α-induced mRNA expression of IL6, IL13, and CXCL10 in HaCaT cells. Furthermore, EEVP restored the IFN-γ/TNF-α-induced downregulation of heme oxygenase (HO)-1 in HaCaT cells by inducing nuclear factor erythroid 2-related factor 2 (Nrf2) expression. A molecular docking analysis demonstrated that EEVP components have a strong affinity to the Kelch-like ECH-associated protein 1 Kelch domain. In summary, EEVP inhibits inflammatory AD by attenuating immune cell activation and inducing the Nrf2/HO-1 signaling pathway in skin keratinocytes.

Betanin ameliorates fipronil-induced nephrotoxicity via activation of Nrf2-HO-1/NQO-1 pathway in albino rat model.

Fipronil (FPN) is phenylpyrazole insecticide extensively used to control a wide variety of pests. Betanin (BET) is a natural colorant with promising antioxidant and anti-inflammatory effects. This study aimed to investigate the potential protective effect of BET on FPN induced nephrotoxicity in adult male albino rats. Forty rats were assigned into 4 equal groups; Group I (Control); Group II (BET) received 20mg/kg b.wt/day; Group III (FPN) received 4.8mg/kg b.wt/day; and Group IV (BET/FPN). All treatments were given orally for 90days. At the end of experiment, blood samples were collected for analysis of serum urea and creatinine. Kidneys were harvested for determination of kidney injury molecule-1(KIM-1) level; gene expression of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and NAD(P)H: quinone oxidoreductase-1 (NQO-1); oxidative stress biomarkers including malondialdehyde (MDA), protein carbonyl content (PCC), catalase activity (CAT), glutathione peroxidase (GPx), and reduced glutathione (GSH). Histopathological examination and immunohistochemical investigation of Nrf2, nuclear factor kappa B (NF-κB), and caspase-3 were also undertaken. The results revealed kidney dysfunction, downregulation of Nrf2, HO-1, and NQO-1 genes, redox imbalance, structural damage, decreased Nrf2 and increased NF-κB immune-expression, in addition to strong caspase-3 immunoreactivity in FPN-treated group. In the combined group, BET co-administration resulted in functional and structural amelioration, up-regulation of Nrf2, HO-1, and NQO-1 genes, mitigation of redox imbalance, and strong anti-inflammatory and antiapoptotic effects. In conclusion, BET via activation of Nrf2-HO-1/NQO-1 pathway, exhibits beneficial antioxidant, anti-inflammatory, and antiapoptotic effects against FPN-induced nephrotoxicity.

BACH1 promotes clear cell renal cell carcinoma progression by upregulating oxidative stress-related tumorigenicity.

The carcinogenesis and progression of renal cell carcinoma (RCC), a heterogeneous cancer derived from renal tubular epithelial cells, is closely related to oxidative stress responses (OSRs). Oxidative stress responses participate in various biological processes related to the metabolism and metastatic potential of cancer such as inflammation, epithelial-mesenchymal transition (EMT), and angiogenesis. In this study, we investigated the role of broad complex-tramtrack-bric-a-brac and cap 'n' collar homology 1 (BACH1), a key transcription factor for OSRs, in clear cell RCC (ccRCC) development and prognosis. The poor prognosis and elevation of serum inflammation markers in nephrectomized ccRCC patients were correlated with the intratumor expression of BACH1 accompanied by a downregulation of heme oxygenase-1. BACH1 contributes to the invasion and migration abilities of RCC cell lines without affecting their proliferation in vitro. In contrast, BACH1 contributes to tumor progression in vivo, in relation to OSRs with the activation of EMT-related pathways. BACH1 involvement in other OSR-linked pathways, including inflammatory responses, angiogenesis, and mTOR signaling, was further revealed by RNA sequencing analysis of BACH1-knockdown cells. In conclusion, the crucial role of BACH1 in the pathogenesis and poor prognosis of ccRCC through the promotion of OSRs is suggested.

Investigation of the toxicity of a glyphosate-based herbicide in a human liver cell line: Assessing the involvement of Nrf2 pathway and protective effects of vitamin E and α-lipoic acid

Glyphosate-based herbicides (GBHs) are the most widely used herbicides all over the world and has gained more attention in recent years because of health safety concerns. In this study, Roundup, one of the most popular glyphosate formulations, was used to evaluate cytotoxic, oxidative stress and apoptosis inducing effects of GBHs in a human hepatocellular cell line (HepG2). Roundup was shown to significantly increase cellular reactive oxygen species (ROS) levels, which lead to activation of the nuclear factor-erythroid-2-related factor 2 (Nrf2) antioxidant defense pathway including reduced levels of heme oxygenase 1 (HO-1). Furthermore, Roundup was found to induce apoptosis and further analysis confirmed involvement of a mitochondrial-dependent pathway verified by increased Bax/Bcl-2 ratios. Investigation of the protective effects of antioxidants vitamin E (Vit E) and α-lipoic acid (LA) against Roundup toxicity showed that both antioxidants significantly reduced the cytotoxicity, ROS formation, HO-1 downregulation, and apoptosis and that Vit E did so more efficiently than LA. In conclusion, our findings highlight the ROS producing and apoptosis inducing effects associated with GBHs, the activation of Nrf2 pathway as a defense mechanism and the protective effects of Vit E and LA against GBH toxicity.

Metformin suppresses foam cell formation, inflammation and ferroptosis via the AMPK/ERK signaling pathway in ox‑LDL‑induced THP‑1 monocytes.

Numerous studies have shown that the formation of foam cells is of vital importance in the process of atherosclerosis. The aim of the present study was to assess the effects of metformin on foam cell formation in oxidized low-density lipoprotein (ox-LDL)-treated THP-1 cells and explore its associated mechanism of action. Human monocytic THP-1 cells were pretreated with metformin for 2 h and subsequently treated with ox-LDL for 24 h. The data indicated that metformin significantly inhibited lipid accumulation in ox-LDL-treated THP-1 cells by decreasing the expression of scavenger receptor A, cluster of differentiation 36 and adipocyte enhancer-binding protein 1. In addition, metformin increased the expression levels of scavenger receptor B1 and ATP binding cassette transporter G1 and suppresses the esterification of free cholesterol. Furthermore, it markedly inhibited ferroptosis (reflected by the upregulation of glutathione peroxidase glutathione peroxidase 4 and the downregulation of Heme oxygenase-1). In addition, it caused a marked suppression in the expression levels of cysteinyl aspartate specific proteinase-1, IL-1β, NOD-like receptor protein 3, IL-18 secretion and in the levels of oxidative stress. Metformin attenuated the activation of ERK and facilitated the phosphorylation of 5' adenosine monophosphate-activated protein kinase (AMPK). Treatment of THP-1 cells with an ERK inhibitor reversed these effects, while inhibition of AMPK activity exacerbated the effects noted in ox-LDL-treated THP-1 cells. In conclusion, the present study suggested that metformin suppressed foam cell formation, inflammatory responses and inhibited ferroptosis in ox-LDL-treated macrophages via the AMPK/ERK signaling pathway.

Metallothionein 2A with Antioxidant and Antitumor Activity Is Upregulated by Caffeic Acid Phenethyl Ester in Human Bladder Carcinoma Cells.

Functions of metallothionein 2A (MT2A) in bladder cancer have not been extensively explored even though metallothioneins are regarded as modulators in several biological regulations including oxidation and cancerous development. We evaluated MT2A in bladder carcinoma cells in terms of the mechanisms of regulation and the underlying functions. MT2A overexpression not only downregulated endogenous ROS but also blocked ROS induced by H2O2. We used the annexin V-FITC apoptosis assay to determine the modulation of H2O2-induced cell apoptosis by MT2A expression. Results of immunoblot and reporter assays indicated that caffeic acid phenethyl ester (CAPE) treatment induced MT2A and heme oxygenase-1 (HO-1) expressions; moreover, the involvement of CAPE in either upregulation of the HO-1 expression or downregulation of endogenous ROS is MT2A dependent in bladder carcinoma cells. Knockdown of MT2A increased invasion and cell growth in vitro and in vivo, whereas ectopic overexpression of MT2A had the reverse effect in bladder carcinoma cells. Unlike bladder cancer tissues, the real-time reverse transcriptase-polymerase chain reaction (RT-qPCR) analysis showed a significant level of MT2A mRNA in the normal bladder tissues. Collectively, our results indicated that MT2A is acting as an antioxidant and also a tumor suppressor in human bladder carcinoma cells.

Downregulation of Vascular Hemeoxygenase-1 Leads to Vasculopathy in Systemic Sclerosis.

Systemic sclerosis (SSc) is a terminal disease characterized by vasculopathy, tissue fibrosis, and autoimmunity. Although the exact etiology of SSc remains unknown, endothelial dysfunction, oxidative stress, and calcium handling dysregulation have been associated with a large number of SSc-related complications such as neointima formation, vasculogenesis, pulmonary arterial hypertension, impaired angiogenesis, and cardiac arrhythmias. Hemeoxygenase-1 (HO-1) is an antioxidant enzyme involved in multiple biological actions in the cardiovascular system including vascular tone, angiogenesis, cellular proliferation, apoptosis, and oxidative stress. The aim of this work was to investigate the physiological role of HO-1 and its relevance in the cardiovascular complications occurring in SSc. We found that, in early phases of SSc, the expression of HO-1 in dermal fibroblast is lower compared to those isolated from healthy control individuals. This is particularly relevant as reduction of the HO-1/CO signaling pathway is associated with endothelial dysfunction and vasculopathy. We show evidence of the role of HO-1/carbon monoxide (CO) signaling pathway in calcium handling. Using an in vitro model of pulmonary arterial hypertension (PAH) we investigated the role of HO-1 in Ca2+ mobilization from intracellular stores. Our results indicate that HO-1 regulates calcium release from intracellular stores of human pulmonary arterial endothelial cells. We interrogated the activity of HO-1 in angiogenesis using an organotypic co-culture of fibroblast-endothelial cell. Inhibition of HO-1 significantly reduced the ability of endothelial cells to form tubules. We further investigated if this could be associated with cell motility or migration of endothelial cells into the extracellular matrix synthesized by fibroblasts. By mean of holographic imaging, we studied the morphological and functional features of endothelial cells in the presence of an HO-1 activator and selective inhibitors. Our results demonstrate that inhibition of HO-1 significantly reduces cell proliferation and cell motility (migration) of cultured endothelial cells, whilst activation of HO-1 does not modify either morphology, proliferation or motility. In addition, we investigated the actions of CO on the Kv7.1 (KCQN1) channel current, an important component of the cardiac action potential repolarization. Using electrophysiology (whole-cell patch-clamp in a recombinant system overexpressing the KCQN1 channel), we assessed the regulation of KCQN1 by CO. CORM-2, a CO donor, significantly reduced the Kv7.1 current, suggesting that HO-1/CO signaling may play a role in the modulation of the cardiac action potential via regulation of this ion channel. In summary, our results indicate a clear link between: 1) downregulation of HO-1/CO signaling; and 2) pathophysiological processes occurring in early phases of SSc, such as calcium homeostasis dysregulation, impaired angiogenesis and cardiac arrhythmias. A better understanding of the canonical actions (mainly due to the biological actions of CO), and non-canonical actions of HO-1, as well as the interaction of HO-1/CO signaling with other gasotransmitters in SSc will contribute to the development of novel therapeutic approaches.

Role of MicroRNA-155 in Triptolide-induced hepatotoxicity via the Nrf2-Dependent pathway

Ethnopharmacological relevanceTriptolide (TP), the main bioactive and toxic ingredient of Tripterygium wilfordii Hook F, causes severe toxicity, particularly for hepatotoxicity. However, the underlying mechanisms for its hepatotoxicity are not entirely clear. Aim of the studyThe purpose of the study was to explore the role of miR-155, a microRNA closely related to various liver injuries and a regulator of the nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant pathway, in TP-induced liver injury in vitro and in vivo. Materials and methodsFirst, in vitro L02 cells were treated with different concentrations of TP. The protein levels of Nrf2 and its downstream genes Heme oxygenase1 (HO-1) were determined by Western blot. The mRNA expression of miR-155, Nrf2, NAD(P)H: quinone oxidoreductase 1 (NQO1) and HO-1 were measured using qRT-PCR. And we transfected miR-155 inhibitor and miminc before TP treatment to determine the mRNA and/or protein levels of miR-155, Nrf2 and HO-1. Then, we further confirmed the interaction between miR-155 and Nrf2 pathway in TP-induced hepatic injury in BALB/C mice. The degree of liver injury was determined by HE staining and serum biochemical. The mRNA expression of miR-155 was examined with qRT-PCR and Nrf2 and HO-1 gene expression in liver were evaluated by immunohistochemistry and/or Western blot. ResultsThe results showed that TP significantly induced the expression of miR-155 both in L02 cells and in rodents liver tissue, and the inhibition of miR-155 could mitigate the hepatic damages caused by TP. Further experiments demonstrated that the inhibition of miR-155 reversed the down-regulation of Nrf2 and HO-1 by TP, while the miR-155 mimic enhanced the effects of TP. Animal experiments also showed that the inhibition of miR-155 by miR-155 antagomir reversed the decrease of Nrf2 induced by TP administration. ConclusionsThese results indicated that miR-155 played an important role in TP-induced hepatotoxicity by regulating the Nrf2 signaling pathway.

Antitumor Effect of 5-Aminolevulinic Acid Through Ferroptosis in Esophageal Squamous Cell Carcinoma.

Due to its tumor-specific metabolic pathway characteristics, 5-aminolevulinic acid (5-ALA) is a natural amino acid widely used in cancer treatment. The current study, demonstrated that 5-ALA induced ferroptosis via glutathione peroxidase 4 (GPX4) and heme oxygenase 1 (HMOX1) and had an antitumor effect in esophageal squamous cell carcinoma (ESCC). Expression of GPX4 and HMOX1 in pathologic specimens of 97 ESCC patients was examined, and prognostic analyses were performed. Real-time polymerase chain reaction (RT-PCR), RNA microarray, and Western blotting analyses were used to evaluate the role of 5-ALA in ferroptosis in vitro. In addition, this study used ferrostatin-1, a ferroptosis inhibitor, and a lipid peroxidation reagent against cell lines treated with 5-ALA. Finally, the role of 5-ALA was confirmed by its effect on an ESCC subcutaneous xenograft mouse model. The study showed that upregulation of GPX4 and downregulation of HMOX1 were poor prognostic factors in ESCC. In an RNA microarray analysis of KYSE30, ferroptosis was one of the most frequently induced pathways, with GPX4 suppressed and HMOX1 overexpressed by 5-ALA treatment. These findings were verified by RT-PCR and Western blotting. Furthermore, 5-ALA led to an increase in lipid peroxidation and exerted an antitumor effect in various cancer cell lines, which was inhibited by ferrostatin-1. In vivo, 5-ALA suppressed GPX4 and overexpressed HMOX1 in tumor tissues and led to a reduction in tumor size. Modulation of GPX4 and HMOX1 by 5-ALA induced ferroptosis in ESCC. Thus, 5-ALA could be a promising new therapeutic agent for ESCC.

Heme/Hemeoxygenase-1 System Is a Potential Therapeutic Intervention for COVID-19 Patients with Severe Complications.

Acute respiratory distress syndrome (ARDS) is one of the critical stages of COVID-19, leading to lung injury and hemolysis. Dysfunctional hemoglobin (Hb) suffers low-level oxygenation, overloaded iron, and down-regulation of hemeoxygenase-1 (HO-1), representing potential therapeutic interventions. This Viewpoint outlines the Hb-HO-1 system as a host-cell target, and proposes possible therapies, including iron chelation and CO therapies, against COVID-19 with ARDS.

Heme oxygenase-1 inhibition mediates Gas6 to enhance bortezomib-sensitivity in multiple myeloma via ERK/STAT3 axis.

Chemoresistance is still a critical challenge for efficient treatment of multiple myeloma (MM) during the bortezomib-based chemotherapy. Recent studies have suggested that heme oxygenase-1 (HO-1) is involved in apoptosis, proliferation and chemoresistance in cancer cells. Here we aim to investigate the role and mechanism of HO-1 in bortezomib-sensitivity to myeloma cells. In the study population, we found that HO-1 was highly expressed in CD138+ primary myeloma cells, which was positively associated with Gas6 expression and Gas6 plasma levels in MM patients. Downregulation of HO-1 using pharmacological inhibitor ZnPPIX or siRNA knockdown significantly enhanced myeloma cell sensitivity to bortezomib in human primary CD138+ cells, U266 and RPMI8226 cell lines. Mechanistically, HO-1 regulated Gas6 production via ERK/STAT3 axis. Combination with HO-1 inhibition increased bortezomib-induced apoptosis and antiproliferative effects via suppressing Gas6 production. These findings suggest that combination of bortezomib and HO-1 inhibitor may serve as a promising therapeutic target against bortezomib-resistant MM.

Lysosomal Destabilizing Drug Siramesine and the Dual Tyrosine Kinase Inhibitor Lapatinib Induce a Synergistic Ferroptosis through Reduced Heme Oxygenase-1 (HO-1) Levels.

Ferroptosis is an iron-dependent type of cell death distinct from apoptosis or necrosis characterized by accumulation of reactive oxygen species. The combination of siramesine, a lysosomotropic agent, and lapatinib, a dual tyrosine kinase inhibitor (TKI), synergistically induced cell death in breast cancer cells mediated by ferroptosis. In this study, we showed that this combination of siramesine and lapatinib induces synergistic cell death in glioma cell line U87 and lung adenocarcinoma cell line A549. This cell death was characterized by the increase in iron content, reactive oxygen species (ROS) production, and lipid peroxidation accumulation after 24 hours of treatment. Moreover, iron chelator DFO and ferrostatin-1, a ferroptosis inhibitor, significantly reduced cell death. The mechanism underlying the activation of the ferroptotic pathway involves lysosomal permeabilization and increase in reactive iron levels in these cells. In addition, the downregulation of heme oxygenase-1 (HO-1) protein occurred. Overexpression of HO-1 resulted in reduction of ROS and lipid peroxidation production and cell death. Furthermore, knocking down of HO-1 combined with siramesine treatment resulted in increased cell death. Finally, we found that the inhibition of the proteasome system rescued HO-1 expression levels. Our results suggest that the induction of ferroptosis by combining a lysosomotropic agent and a tyrosine kinase inhibitor is mediated by iron release from lysosomes and HO-1 degradation by the proteasome system.

HO-1 downregulation favors BRAFV600 melanoma cell death induced by Vemurafenib/PLX4032 and increases NK recognition.

Heme oxygenase 1 (HO-1) plays a pivotal role in preventing cell damage. Indeed, through the antioxidant, antiapoptotic and anti-inflammatory properties of its metabolic products, it favors cell adaptation against different stressors. However, HO-1 induction has also been related to the gain of resistance to therapy in different types of cancers and its involvement in cancer immune-escape has been hypothesized. We have investigated the role of HO-1 expression in Vemurafenib-treated BRAFV600 melanoma cells in modulating their susceptibility to NK cell-mediated recognition. Different cell lines, isolated in house from melanoma patients, have been exposed to 1-10 μM PLX4032, which efficiently reduced ERK phosphorylation. In three lines, Vemurafenib was able to induce only a limited decrease in cell viability, while HO-1 expression was upregulated. HO-1 silencing/inhibition was able to induce a further significant reduction of Vemurafenib-treated melanoma viability. Moreover, while NK cell degranulation and killing activity were decreased upon interaction with melanoma exposed to Vemurafenib, HO-1 silencing was able to completely restore NK cell ability to degranulate and kill. Furthermore, melanoma cell treatment with Vemurafenib downregulated the expression of ligands of NKp30 and NKG2D activating receptors, and HO-1 silencing/inhibition was able to restore their expression. Our results indicate that HO-1 downregulation can both improve the efficacy of Vemurafenib on melanoma cells and favor melanoma susceptibility to NK cell-mediated recognition and killing.

Cellular cholesterol modifies flow-mediated gene expression.

Downregulation of heme oxygenase-1 (HO-1), cyclooxygenase-2 (COX2), and nitric oxide synthase-2 (NOS2) in the kidneys of Dahl rodents causes salt sensitivity, while restoring their expression aids in Na+ excretion and blood pressure reduction. Loading cholesterol into collecting duct (CD) cells represses fluid shear stress (FSS)-mediated COX2 activity. Thus, we hypothesized that cholesterol represses flow-responsive genes necessary to effectuate Na+ excretion. To this end, CD cells were used to test whether FSS induces these genes and if cholesterol loading represses them. Mice fed either 0% or 1% cholesterol diet were injected with saline, urine volume and electrolytes were measured, and renal gene expression determined. FSS-exposed CD cells demonstrated increases in HO-1 mRNA by 350-fold, COX2 by 25-fold, and NOS2 by 8-fold in sheared cells compared with static cells (P < 0.01). Immunoblot analysis of sheared cells showed increases in HO-1, COX2, and NOS2 protein, whereas conditioned media contained more HO-1 and PGE2 than static cells. Cholesterol loading repressed the sheared mediated protein abundance of HO-1 and NOS2 as well as HO-1 and PGE2 concentrations in media. In cholesterol-fed mice, urine volume was less at 6 h after injection of isotonic saline (P < 0.05). Urinary Na+ concentration, urinary K+ concentration, and osmolality were greater, whereas Na+ excretion was less, at the 6-h urine collection time point in cholesterol-fed versus control mice (P < 0.05). Renal cortical and medullary HO-1 (P < 0.05) and NOS2 (P < 0.05) mRNA were repressed in cholesterol-fed compared with control mice. Cholesterol acts to repress flow induced natriuretic gene expression, and this effect, in vivo, may contribute to renal Na+ avidity.

Beneficial Role of HO-1-SIRT1 Axis in Attenuating Angiotensin II-Induced Adipocyte Dysfunction.

Background: Angiotensin II (Ang II), released by the renin–angiotensin–aldosterone system (RAAS), contributes to the modulatory role of the RAAS in adipose tissue dysfunction. Investigators have shown that inhibition of AngII improved adipose tissue function and insulin resistance in mice with metabolic syndrome. Heme Oxygenase-1 (HO-1), a potent antioxidant, has been demonstrated to improve oxidative stress and adipocyte phenotype. Molecular effects of high oxidative stress include suppression of sirtuin-1 (SIRT1), which is amenable to redox manipulations. The mechanisms involved, however, in these metabolic effects of the RAAS remain incompletely understood. Hypothesis: We hypothesize that AngII-induced oxidative stress has the potential to suppress adipocyte SIRT1 via down regulation of HO-1. This effect of AngII will, in turn, upregulate mineralocorticoid receptor (MR). The induction of HO-1 will rescue SIRT1, hence improving oxidative stress and adipocyte phenotype. Methods and Results: We examined the effect of AngII on lipid accumulation, oxidative stress, and inflammatory cytokines in mouse pre-adipocytes in the presence and absence of cobalt protoporphyrin (CoPP), HO-1 inducer, tin mesoporphyrin (SnMP), and HO-1 inhibitor. Our results show that treatment of mouse pre-adipocytes with AngII increased lipid accumulation, superoxide levels, inflammatory cytokine levels, interleukin-6 (IL-6) and tumor necrosis factor α (TNFα), and adiponectin levels. This effect was attenuated by HO-1 induction, which was further reversed by SnMP, suggesting HO-1 mediated improvement in adipocyte phenotype. AngII-treated pre-adipocytes also showed upregulated levels of MR and suppressed SIRT1 that was rescued by HO-1. Subsequent treatment with CoPP and SIRT1 siRNA in mouse pre-adipocytes increased lipid accumulation and fatty acid synthase (FAS) levels, suggesting that beneficial effects of HO-1 are mediated via SIRT1. Conclusion: Our study demonstrates for the first time that HO-1 has the ability to restore cellular redox, rescue SIRT1, and prevent AngII-induced impaired effects on adipocytes and the systemic metabolic profile.

A metal-free near-infrared fluorescent probe for tracking the glucose-induced fluctuations of carbon monoxide in living cells and zebrafish

In this work, by taking full advantage of the transformation of nitro group into amino moiety under the direct reduction of CO, a new metal-free colorimetric and near-infrared fluorescent probe NIR-CO for rapid and specific tracing of intracellular CO has been constructed, and it also become the first reaction-based near-infrared fluorescent probe for CO detection without additional reagents. Probe NIR-CO could quantitatively detect CO at the nanomolar level and the detection limit was calculated as low as 6.1 nM. Additionally, probe NIR-CO with preeminent sensing properties was successfully applied to monitor the fluctuations of endogenous CO levels in living systems. In particular, the up-regulation of heme oxygenase-1 (HO-1) caused by transient glucose deprivation (TGD) in living cells and the down-regulation of HO-1 inhibited by high glucose (HG) in zebrafish were confirmed for the first time via mapping the glucose-induced fluctuations of CO levels. Thus, we anticipate that probe NIR-CO not only can serve as a powerful tool to investigate the detailed biological functions of CO in the pathophysiological processes, but also possesses potential applications of in situ monitoring HO-1 activity in the complex biological systems.