Osteomesopyknosis associated with a novel ALOX5 variant that impacts the RANKL pathway.

BACKGROUND: Bone tissue homeostasis relies on the coordinated activity of the bone-forming osteoblasts and bone-resorbing osteoclasts. Osteomesopyknosis is considered a distinctive rare sclerosing skeletal disorder of unelucidated pathophysiology and presumably autosomal dominant transmission. However, the causal genes are unknown. METHODS: We present a case report encompassing clinical assessments, imaging studies, and whole-exome sequencing analysis, complemented by functional in vitro experiments. RESULTS: This new case of osteomesopyknosis was associated with a missense ALOX5 variant predicted to induce protein misfolding and proteasomal degradation. Transfection experiments demonstrated that the variant was associated with reduced protein levels restored by proteasomal inhibition with bortezomib. Likewise, gene expression analysis showed that the mutated gene was associated with a decreased RANKL/OPG ratio, which is a critical driver of osteoclast precursor differentiation. CONCLUSION: Our data indicate impaired bone resorption as the underlying mechanism of this rare osteosclerosis, implicating ALOX5 pathogenic variants as potential etiological factors.

In Vitro Inhibition of Colorectal Cancer Gene Targets by Withania somnifera L. Methanolic Extracts: A Focus on Specific Genome Regulation.

An approach that shows promise for quickening the evolution of innovative anticancer drugs is the assessment of natural biomass sources. Our study sought to assess the effect of W. somnifera L. (WS) methanolic root and stem extracts on the expression of five targeted genes (cyclooxygenase-2, caspase-9, 5-Lipoxygenase, B-cell lymphoma-extra-large, and B-cell lymphoma 2) in colon cancer cell lines (Caco-2 cell lines). Plant extracts were prepared for bioassay by dissolving them in dimethyl sulfoxide. Caco-2 cell lines were exposed to various concentrations of plant extracts, followed by RNA extraction for analysis. By explicitly relating phytoconstituents of WS to the dose-dependent overexpression of caspase-9 genes and the inhibition of cyclooxygenase-2, 5-Lipoxygenase, B-cell lymphoma-extra-large, and B-cell lymphoma 2 genes, our novel findings characterize WS as a promising natural inhibitor of colorectal cancer (CRC) growth. Nonetheless, we recommend additional in vitro research to verify the current findings. With significant clinical benefits hypothesized, we offer WS methanolic root and stem extracts as potential organic antagonists for colorectal carcinogenesis and suggest further in vivo and clinical investigations, following successful in vitro trials. We recommend more investigation into the specific phytoconstituents in WS that contribute to the regulatory mechanisms that inhibit the growth of colon cancer cells.

The role of human 5-Lipoxygenase (5-LO) in carcinogenesis - a question of canonical and non-canonical functions.

5-Lipoxygenase (5-LO), a fatty acid oxygenase, is the central enzyme in leukotriene (LT) biosynthesis, potent arachidonic acid-derived lipid mediators released by innate immune cells, that control inflammatory and allergic responses. In addition, through interaction with 12- and 15-lipoxgenases, the enzyme is involved in the formation of omega-3 fatty acid-based oxylipins, which are thought to be involved in the resolution of inflammation. The expression of 5-LO is frequently deregulated in solid and liquid tumors, and there is strong evidence that the enzyme plays an important role in carcinogenesis. However, global inhibition of LT formation and signaling has not yet shown the desired success in clinical trials. Curiously, the release of 5-LO-derived lipid mediators from tumor cells is often low, and the exact mechanism by which 5-LO influences tumor cell function is poorly understood. Recent data now show that in addition to releasing oxylipins, 5-LO can also influence gene expression in a lipid mediator-independent manner. These non-canonical functions, including modulation of miRNA processing and transcription factor shuttling, most likely influence cancer cell function and the tumor microenvironment and might explain the low clinical efficacy of pharmacological strategies that previously only targeted oxylipin formation and signaling by 5-LO. This review summarizes the canonical and non-canonical functions of 5-LO with a particular focus on tumorigenesis, highlights unresolved issues, and suggests future research directions.

ALOX5 drives the pyroptosis of CD4+ T cells and tissue inflammation in rheumatoid arthritis.

Pyroptosis, an inflammatory form of programmed cell death, is linked to the pathology of rheumatoid arthritis (RA). Here, we investigated the molecular mechanism underlying pyroptosis in T cells isolated from patients with RA. Compared with healthy individuals, patients with RA had more pyroptotic CD4+ T cells in blood and synovia, which correlated with clinical measures of disease activity. Moreover, the mRNA expression and protein abundance of arachidonate 5-lipoxygenase (ALOX5), which converts arachidonic acid to leukotriene A4 (LTA4), were increased in CD4+ T cells from patients with RA and, among patients with RA, were lowest in those in clinical remission. Knockdown or pharmacological inhibition of ALOX5 suppressed CD4+ T cell pyroptosis and improved symptoms in two rodent models of RA. Mechanistically, the increase in ALOX5 activity in RA CD4+ T cells enhanced the production of the LTA4 derivative LTB4, which stimulated Ca2+ influx through ORAI3 channels, leading to the activation of NLRP3 inflammasomes and pyroptosis. Our findings reveal a role for ALOX5 in RA and provide a molecular basis for further exploring the clinical utility of ALOX5 inhibition in RA and for using ALOX5 as a biomarker to distinguish active disease and remission in RA.

Magnolin alleviated DSS-induced colitis by inhibiting ALOX5-mediated ferroptosis.

Inflammatory bowel disease (IBD) is a chronic and incurable disorder associated with higher cancer risk and currently faces unsatisfactory treatment outcomes. Ferroptotic cells secrete damage-associated molecular patterns (DAMPs) that recruit and activate immune cells, particularly macrophages. Magnolin has excellent antioxidant and anti-inflammatory properties, but its effect on IBD has not yet been clearly understood. This study aimed to investigate the therapeutic effects and mechanism of magnolin in IBD. For this purpose, in vivo and in vitro colitis models were established using dextran sulfate sodium (DSS), followed by optimization of magnolin concentration 2.5 µg/mL in vitro and 5 mg/kg in vivo. Bioinformatics analysis identified potential magnolin target sites and evaluated ferroptosis-associated gene expressions. Body weight, food intake, disease activity index (DAI), pathological changes, and inflammation levels were assessed. The effect of magnolin on ferroptosis and macrophages was evaluated using quantitative real time-polymerase chain reaction (qRT-PCR), immunofluorescent staining, flow cytometry, enzyme-linked immunosorbent assay (ELISA), and western blotting. Results indicated that magnolin at a lower dose (5 mg/kg) alleviated DSS-induced colitis symptoms and reduced inflammation in mice. The bioinformatics analysis showed arachidonate 5-lipoxygenase (ALOX5) as a potential magnolin target. Furthermore, magnolin inhibited the expression of ALOX5 with no effect on GPX4. Moreover, magnolin regulated macrophage differentiation into the M2 phenotype and suppressed pro-inflammatory factors, that is, interleukin-6 and tumor necrosis factor-α (IL-6 and TNFα). These results suggested that magnolin possesses significant therapeutic potential in treating IBD by suppressing ALOX5-mediated ferroptosis, inhibiting M1 while promoting M2 macrophages, which is envisaged to provide novel strategies for treating IBD.

Dysregulated Leukotriene Metabolism in Patients with COVID-19.

This study aimed to examine the leukotriene metabolism during COVID-19. In total, 180 participants were included in this study, of which 60 were healthy controls, 60 required intensive care units (ICU), and 60 did not require intensive care (non-ICU). The serum levels of 5-lipoxygenase (5-LO), 5-LO activating protein (ALOX5AP), and cysteinyl leukotriene (CYSLT) were measured, and the mRNA expression levels of 5-LO, ALOX5AP, and cysteinyl leukotriene receptor 1 (CYSLTR1) were investigated. Compared with the control group, both the non-ICU and ICU groups had lower levels of 5-LO and mRNA expression. ICU patients had lower levels of 5-LO and mRNA expression than non-ICU patients. CYSLTR1 mRNA expression was highest in the ICU group, followed by the non-ICU group, and healthy controls had the lowest mRNA expression levels. CYSLT levels were higher in the control group than in the non-ICU and ICU groups. CYSLTR1 expression was higher in patients than in controls; therefore, selective leukotriene receptor blockers can be used as treatment options. CYSLTR1 expression was higher in the ICU group than in the non-ICU group. Furthermore, CYSLTR1 mRNA expression may be a promising biomarker of COVID-19 severity.

ALOX5 deficiency contributes to bladder cancer progression by mediating ferroptosis escape.

Ferroptosis is an iron-dependent form of regulated cell death driven by the lethal lipid peroxides. Previous studies have demonstrated that inducing ferroptosis holds great potential in cancer therapy, especially for patients with traditional therapy failure. However, cancer cells can acquire ferroptosis evasion during progression. To date, the therapeutic potential of inducing ferroptosis in bladder cancer (BCa) remains unclear, and whether a ferroptosis escape mechanism exists in BCa needs further investigation. This study verified that low pathological stage BCa cells were highly sensitive to RSL3-induced ferroptosis, whereas high pathological stage BCa cells exhibited obviously ferroptosis resistance. RNA-seq, RNAi-mediated loss-of-function, and CRISPR/Cas9 experiments demonstrated that ALOX5 deficiency was the crucial factor of BCa resistance to ferroptosis in vitro and in vivo. Mechanistically, we found that ALOX5 deficiency was regulated by EGR1 at the transcriptional level. Clinically, ALOX5 expression was decreased in BCa tissues, and its low expression was associated with poor survival. Collectively, this study uncovers a novel mechanism for BCa ferroptosis escape and proposes that ALOX5 may be a valuable therapeutic target and prognostic biomarker in BCa treatment.

Oncogenic PIK3CA recruits myeloid-derived suppressor cells to shape the immunosuppressive tumour microenvironment in luminal breast cancer through the 5-lipoxygenase-dependent arachidonic acid pathway.

BACKGROUND: Oncogenic PIK3CA mutations (PIK3CAmut ) frequently occur in a higher proportion in luminal breast cancer (LBC), especially in refractory advanced cases, and are associated with changes in tumour cellular metabolism. Nevertheless, its effect on the progression of the immune microenvironment (TIME) within tumours and vital molecular events remains veiled. METHODS: Multiplex immunohistochemistry (mIHC) and single-cell mass cytometry (CyTOF) was used to describe the landscape of TIME in PIK3CAmut LBC. The PIK3CA mutant cell lines were established using CRISPER/Cas9 system. The gene expression levels, protein secretion and activity of signaling pathways were measured by real-time RT-PCR, ELISA, immunofluorescence staining or western blotting. GSEA analysis, transwell chemotaxis assay, live cell imaging, flow cytometry metabolite analysis targeting arachidonic acid, Dual-luciferase reporter assay, and Chromatin immunoprecipitation assay were used to investigate the underlying function and mechanism of the PI3K/5-LOX/LTB4 axis. RESULTS: PIK3CAmut LBC cells can induce an immunosuppressive TIME by recruiting myeloid-derived suppressor cells (MDSCs) and excluding cytotoxic T cells via the arachidonic acid (AA) metabolism pathway. Mechanistically, PIK3CAmut activates the transcription of 5-lipoxygenase (5-LOX) in a STAT3-dependent manner, which in turn directly results in high LTB4 production, binding to BLT2 on MDSCs and promoting their infiltration. Since a suppressive TIME is a critical barrier for the success of cancer immunotherapy, the strategies that can convert "cold" tumours into "hot" tumours were compared. Targeted therapy against the PI3K/5-LOX/LTB4 axis synergizing with immune checkpoint blockade (ICB) therapy achieved dramatic shrinkage in vivo. CONCLUSIONS: The results emphasize that PIK3CAmut can induce immune evasion by recruiting MDSCs through the 5-LOX-dependent AA pathway, and combination targeted therapy with ICB may provide a promising treatment option for refractory advanced LBC patients.

Human cytomegalovirus infection enhances 5­lipoxygenase and cycloxygenase­2 expression in colorectal cancer.

Colorectal cancer (CRC) is one of the most common and fatal types of cancer. Inflammation promotes CRC development, however, the underlying etiological factors are unknown. Human cytomegalovirus (HCMV), a virus that induces inflammation and other cancer hallmarks, has been detected in several types of malignancy, including CRC. The present study investigated whether HCMV infection was associated with expression of the pro­inflammatory enzymes 5­lipoxygenase (5­LO) and cyclooxygenase­2 (COX­2) and other molecular, genetic and clinicopathological CRC features. The present study assessed 146 individual paraffin­embedded CRC tissue microarray (TMA) cores already characterized for TP53 and KRAS mutations, microsatellite instability (MSI) status, Ki­67 index and EGFR by immunohistochemistry (IHC). The cores were further analyzed by IHC for the expression of two HCMV proteins (Immediate Early, IE and pp65) and the inflammatory markers 5­LO and COX­2. The CRC cell lines Caco­2 and LS­174T were infected with HCMV strain VR1814, treated with antiviral drug ganciclovir (GCV) and/or anti­inflammatory drug celecoxib (CCX) and analyzed by reverse transcription­quantitative PCR and immunofluorescence for 5­LO, COX­2, IE and pp65 transcripts and proteins. HCMV IE and pp65 proteins were detected in ~90% of the CRC cases tested; this was correlated with COX­2, 5­LO and KI­67 expression, but not with EGFR immunostaining, TP53 and KRAS mutations or MSI status. In vitro, HCMV infection upregulated 5­LO and COX­2 transcript and proteins in both Caco­2 and LS­174T cells and enhanced cell proliferation as determined by MTT assay. Treatment with GCV and CCX significantly decreased the transcript levels of COX­2, 5­LO, HCMV IE and pp65 in infected cells. HCMV was widely expressed in CRC and may promote inflammation and serve as a potential new target for CRC therapy.

Association between a single nucleotide polymorphism of the ALOX5 gene and susceptibility to multisystem tuberculosis in a Chinese Han population.

BACKGROUND: Host genetic single nucleotide polymorphisms can exert an influence susceptibility to tuberculosis infection. Previous investigations have demonstrated an association between the polymorphism in the ALOX5 gene and a range of diseases, encompassing not only noninfectious conditions like asthma, acute myocardial infarction, and cerebral infarction but also infections caused by various pathogens. However, the relationship between ALOX5 gene polymorphism and susceptibility to tuberculosis has received limited research attention. The ALOX5 gene encodes arachidonic acid 5-lipoxygenase(5-LO), which serves as the initiating catalyst in the generation of the inflammatory mediator leukotriene. Leukotrienes, products derived from the 5-LO pathway, are potent proinflammatory lipid mediators that assume a pivotal role in tuberculosis infections.Consequently, ALOX5 gene variants may be intricately associated with the pathogenesis of tuberculosis. In instances where the host exhibits immunocompromisation, infection with Mycobacterium tuberculosis can impact multiple systems. The involvement of multiple systems significantly augments the complexity of treatment and escalates patient mortality rates. Regrettably, the underlying mechanisms driving multisystem tuberculosis pathogenesis remain enigmatic, with clinicians paying scant attention to this aspect. Although the protein encoded by the ALOX5 gene represents a pivotal enzyme that catalyzes the metabolism of arachidonic acid into LXA4, and thereby plays a significant role in the inflammatory response during tuberculosis infection, studies investigating ALOX5 gene polymorphism and its association with susceptibility to multisystem tuberculosis in the Chinese Han population are exceptionally scarce. Therefore, the primary objective of this study is to comprehensively examine the correlation between ALOX5 gene polymorphisms and susceptibility to tuberculosis within the Chinese Han population, with particular emphasis on multisystemic tuberculosis. METHODS: A case‒control study design was employed, encompassing 382 individuals with pulmonary tuberculosis and 367 individuals with multisystemic tuberculosis as the case groups, along with 577 healthy controls.Whole blood DNA was extracted from all patients and healthy controls. Subsequently, three tag polymorphisms (rs2029253, rs7896431, rs2115819) within the ALOX5 gene were selectively identified and genotyped. RESULTS: After adjusting for age and sex, the presence of allele A at rs2029253 exhibited a pronounced association with an elevated risk of TB susceptibility when compared to the tuberculosis group and healthy control group. (ORa: 2.174, 95% CI: 1.827-2.587; Pa<0.001, respectively). Notably, the rs2029253 AG genotype and AA genotype displayed a significantly increased susceptibility to tuberculosis (ORa: 2.236, 95% CI: 1.769-2.825; Pa <0.001 and ORa: 4.577, 95% CI: 2.950-7.100; Pa <0.001, respectively) compared to the GG genotype. Moreover, in the analysis utilizing genetic models, rs2029253 also exhibited a markedly heightened susceptibility to tuberculosis in additive models, dominant models, and recessive models (Pa <0.001). Conversely, no significant association was observed between rs7896431, rs2115819, and tuberculosis. In the subgroup analysis, when comparing the pulmonary tuberculosis group with the healthy control group, we observed no significant disparities in the distribution frequencies of alleles, genotypes, and gene models (additive model, dominant model, and recessive model) for the three tag SNPs, with P-values were >0.05 after adjusting for age and sex. Additionally, we noted that the presence of allele A at rs2029253 was linked to an increased susceptibility to tuberculosis in the multisystemic tuberculosis group relative to the healthy control group (ORa: 2.292, 95% CI: 1.870-2.810; Pa<0.001). Similarly, the rs2029253 AG genotype, AA genotype, and gene models, including the additive model, dominant model, and recessive model, demonstrated a significantly elevated risk of tuberculosis susceptibility. CONCLUSIONS: The polymorphism in the ALOX5 gene is associated with susceptibility to multisystemic tuberculosis in the Chinese Han population.

Transcriptome Analysis of Leg Muscles and the Effects of ALOX5 on Proliferation and Differentiation of Myoblasts in Haiyang Yellow Chickens.

Skeletal muscle growth and development from embryo to adult consists of a series of carefully regulated changes in gene expression. This study aimed to identify candidate genes involved in Haiyang Yellow Chickens' growth and to understand the regulatory role of the key gene ALOX5 (arachidonate 5-lipoxygenase) in myoblast proliferation and differentiation. In order to search the key candidate genes in the process of muscle growth and development, RNA sequencing was used to compare the transcriptomes of chicken muscle tissues at four developmental stages and to analyze the effects of ALOX5 gene interference and overexpression on myoblast proliferation and differentiation at the cellular level. The results showed that 5743 differentially expressed genes (DEGs) (|fold change| ≥ 2; FDR ≤ 0.05) were detected by pairwise comparison in male chickens. Functional analysis showed that the DEGs were mainly involved in the processes of cell proliferation, growth, and developmental process. Many of the DEGs, such as MYOCD (Myocardin), MUSTN1 (Musculoskeletal Embryonic Nuclear Protein 1), MYOG (MYOGenin), MYOD1 (MYOGenic differentiation 1), FGF8 (fibroblast growth factor 8), FGF9 (fibroblast growth factor 9), and IGF-1 (insulin-like growth factor-1), were related to chicken growth and development. KEGG pathway (Kyoto Encyclopedia of Genes and Genomes pathway) analysis showed that the DEGs were significantly enriched in two pathways related to growth and development: ECM-receptor interaction (Extracellular Matrix) and MAPK signaling pathway (Mitogen-Activated Protein Kinase). With the extension of differentiation time, the expression of the ALOX5 gene showed an increasing trend, and it was found that interference with the ALOX5 gene could inhibit the proliferation and differentiation of myoblasts and that overexpression of the ALOX5 gene could promote the proliferation and differentiation of myoblasts. This study identified a range of genes and several pathways that may be involved in regulating early growth, and it can provide theoretical research for understanding the regulation mechanism of muscle growth and development of Haiyang Yellow Chickens.

Role of ALOX5 in non-small cell lung cancer: A potential therapeutic target associated with immune cell infiltration. / ALOX5å¯ä½œä¸ºä¸Žå ç–«ç»†èƒžæµ¸æ¶¦ç›¸å ³çš„éžå°ç»†èƒžè‚ºç™Œé¢„åŽç”Ÿç‰©æ ‡å¿—ç‰©.

OBJECTIVES: The efficacy of immunotherapy for lung cancer is closely related to immune cell infiltration. Arachidonic acid 5-lipoxygenase (ALOX5) can activate inflammatory responses and trigger various cell death patterns; however, the relevance of ALOX5 to immune cell infiltration in lung cancer is unclear. The expression of ALOX5 in non-small cell lung cancer (NSCLC) is analyzed using an online database to explore the correlation between ALOX5 and immune cell infiltration in NSCLC and its relationship with prognosis. METHODS: Differences in ALOX5 expression in NSCLC and normal lung tissues were analyzed by online databases such as TIMER, GEPIA and HPA; the UALCAN database was used to reveal the relationship between ALOX5 and clinical features; Kaplan-Meier database was applied to explore the prognostic value of ALOX5; GeneMANIA and String Website was used to explore genes and proteins associated with ALOX5 expression, respectively; the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were used to analyze ALOX5 differential genes which were picked up through the TCGA database; GSEA software was applied to predict the signal pathways that ALOX5 may be involved in; and the TIMER database was used to analyze the effect of ALOX5 expression on the level of immune cell infiltration. RESULTS: Compared with the normal lung tissues, the ALOX5 expression was low in NSCLC tissues (P<0.05), and which affected the prognosis of lung cancer patients. The expression level of ALOX5 was related to clinical features such as sex, age, metastasis, and pathological staging in NSCLC patients (all P<0.05). The gene interaction network analysis found that the genes interacting with ALOX5 mainly included the genes related to lipid oxidation and pro-inflammatory mediators such as coactosin like protein 1 (COTL1), leukotriene C4 synthase (LTC4S), and prostaglandin endoperoxide synthase 2 (PTGS2), and the protein-protein interaction analysis results were consistent. GO and KEGG analysis found that ALOX5 was involved in the biological process of activation of immune cell function and was involved in immune response function pathways. The GSEA analysis showed that ALOX5 may activate immune responses and mediate immune-related prognosis by affecting the cytokine-cytokine receptor interactions, natural killer-mediated cytotoxicity, and T cell receptor signaling pathways. The ALOX5 mRNA expressions in lung adenocarcinoma and lung squamous cell carcinoma were positively correlated with the tumor infiltration immune cells (B cells, CD8+ T cells, CD4+ T cells, etc.) (all P<0.05), and the ALOX5 mRNA expression was positively correlated with the expression of classic T cell immune checkpoint inhibitor genes (P<0.001). CONCLUSIONS: The ALOX5 gene expression in NSCLC is significantly downregulated, and which can affect NSCLC prognosis and immune cell infiltration levels. ALOX5 gene may be a potential biomarker of NSCLC prognosis associated with immune cell infiltration.

Hematopoietic 12/15-lipoxygenase activity negatively contributes to fungal-associated allergic asthma.

Asthma is one of the most common noncommunicable diseases in the world. Approximately 30% of severe cases are associated with fungal sensitization, often associated with allergy to the opportunistic mold Aspergillus fumigatus. Leukotrienes, immunopathogenic mediators derived from the metabolism of arachidonic acid (AA) by 5-lipoxygenase (5-LOX), are often elevated in severe asthma. As such, these mediators are Food and Drug Administration-approved therapeutic targets of the antiasthmatic drugs Zileuton/Zyflo and Singulair/Montelukast. A second enzyme involved in AA metabolism is 12/15-lipoxygenase (12/15-LOX; Alox15). Here, C57BL/6 wild-type (WT) mice subjected to experimental fungal asthma had increased expression of Alox15 mRNA and increased levels of 12-HETE, a product of 12/15-LOX activity, in the lung when compared with naïve and vehicle-treated mice. Mice deficient in 12/15-LOX (Alox15-/-) demonstrated better lung function, as measured by airway hyperresponsiveness (AHR), during fungal asthma. Histological assessment revealed reduced inflammation in the lungs of Alox15-/- mice compared with WT mice, which was corroborated by flow cytometric analysis of multiple myeloid (eosinophils and neutrophils) and lymphoid (CD4+ T and γδ T) cell populations. This was further supported by decreased levels of specific chemokines that promote the recruitment of these cells. Likewise, type 1 and 2, but not type 17 cytokines, were significantly lower in the lungs of Alox15-/- mice. Bone marrow chimera studies revealed that the presence of 12/15-LOX in hematopoietic cells contributed to AHR during fungal asthma. Taken together, our data support the hypothesis that hematopoietic-associated 12/15-LOX contributes to type 1 and 2 responses and exacerbation of allergic fungal asthma.NEW & NOTEWORTHY Humans with asthma sensitized to fungi often have more severe asthma than those who are not sensitized to fungi. Products of arachidonic acid generated via 5-lipoxygenase are often elevated in severe asthma and are successful FDA-approved drug targets. Less understood is the role of products generated via 12/15-lipoxygenase. We demonstrate that 12/15-lipoxygenase expression in hematopoietic cells contributes to type 1 and 2 responses and impaired lung function during allergic fungal asthma.

Multi-walled carbon nanotubes induce arachidonate 5-lipoxygenase expression and enhance the polarization and function of M1 macrophages in vitro.

Fibrogenic carbon nanotubes (CNTs) induce the polarization of M1 and M2 macrophages in mouse lungs. Polarization of the macrophages regulates the production of proinflammatory and pro-resolving lipid mediators (LMs) to mediate acute inflammation and its resolution in a time-dependent manner. Here we examined the molecular mechanism by which multi-walled CNTs (MWCNTs, Mitsui-7) induce M1 polarization in vitro. Treatment of murine macrophages (J774A.1) with Mitsui-7 MWCNTs increased the expression of Alox5 mRNA and protein in a concentration- and time-dependent manner. The MWCNTs induced the expression of CD68 and that induction persisted for up to 3 days post-exposure. The expression and activity of inducible nitric oxide synthase, an intracellular marker of M1, were increased by MWCNTs. Consistent with M1 polarization, the MWCNTs induced the production and secretion of proinflammatory cytokines tumor necrosis factor-α and interleukin-1ß, and proinflammatory LMs leukotriene B4 (LTB4) and prostaglandin E2 (PGE2). The cell-free media from MWCNT-polarized macrophages induced the migration of neutrophilic cells (differentiated from HL-60), which was blocked by Acebilustat, a specific leukotriene A4 hydrolase inhibitor, or LY239111, an LTB4 receptor antagonist, but not NS-398, a cyclooxygenase 2 inhibitor, revealing LTB4 as a major mediator of neutrophil chemotaxis from MWCNT-polarized macrophages. Knockdown of Alox5 using specific small hairpin-RNA suppressed MWCNT-induced M1 polarization, LTB4 secretion, and migration of neutrophils. Taken together, these findings demonstrate the polarization of M1 macrophages by Mitsui-7 MWCNTs in vitro and that induction of Alox5 is an important mechanism by which the MWCNTs promote proinflammatory responses by boosting M1 polarization and production of proinflammatory LMs.

ALOX5 promotes autophagy-dependent ferroptosis by activating the AMPK/mTOR pathway in melanoma.

BACKGROUND: Melanoma has become more common, and its therapeutic management has remained challenging in recent decades. The purpose of our study is to explore new prognostic therapeutic markers of melanoma and to find new therapeutic methods and therapeutic targets of novel drugs, which have great significance. METHOD: First, the arachidonate 5-lipoxygenase (ALOX5) gene associated with both autophagy and ferroptosis was identified by R version 4.2.0. We used human melanoma and para-cancer tissues, human melanoma cell lines, and melanoma-bearing mouse tissues. We used qRT-PCR, Western blotting, immunohistochemistry, immunofluorescence staining, CCK-8, iron ion assay, GSH assay, and MDA assay. In vivo, the ferroptosis activation and antitumor effects of recombinant human ALOX5 protein were evaluated using a xenograft model. RESULT: We report that the downregulation of ALOX5 in melanoma is positively correlated with the prognosis of patients and is an independent prognostic factor. Elevated ALOX5 contributes to autophagy and ferroptosis in vitro and in vivo. At the same time, inhibition of autophagy can reduce ferroptosis enhanced by ALOX5, and autophagy and ALOX5 have a synergistic effect. The results of the mechanistic study showed that the increase in ALOX5 could activate the AMPK/mTOR pathway and inhibit GPX4 expression, promoting the occurrence of autophagy-dependent ferroptosis, while the decrease in p-AMPK/AMPK inhibited the occurrence of ferroptosis. CONCLUSION: ALOX5 deficiency was resistant to autophagy and ferroptosis by inhibiting the AMPK/mTOR pathway. Therefore, it can provide new targets and methods for melanoma drug development.

Three-dimensional growth reveals fine-tuning of 5-lipoxygenase by proliferative pathways in cancer.

The leukotriene (LT) pathway is positively correlated with the progression of solid malignancies, but the factors that control the expression of 5-lipoxygenase (5-LO), the central enzyme in LT biosynthesis, in tumors are poorly understood. Here, we report that 5-LO along with other members of the LT pathway is up-regulated in multicellular colon tumor spheroids. This up-regulation was inversely correlated with cell proliferation and activation of PI3K/mTORC-2- and MEK-1/ERK-dependent pathways. Furthermore, we found that E2F1 and its target gene MYBL2 were involved in the repression of 5-LO during cell proliferation. Importantly, we found that this PI3K/mTORC-2- and MEK-1/ERK-dependent suppression of 5-LO is also existent in tumor cells from other origins, suggesting that this mechanism is widely applicable to other tumor entities. Our data show that tumor cells fine-tune 5-LO and LT biosynthesis in response to environmental changes repressing the enzyme during proliferation while making use of the enzyme under cell stress conditions, implying that tumor-derived 5-LO plays a role in the manipulation of the tumor stroma to quickly restore cell proliferation.

5-Lipoxygenase Contributes to Benzo[a]pyrene-Induced Cytotoxicity and DNA Damage in Human Bronchial Epithelial Cells.

Metabolic activation of indirect-acting carcinogens in target organs is a recognized mechanism of carcinogenesis. This study aimed to determine the role of benzo[a]pyrene (BaP) metabolism enzymes lipoxygenase (LOX), cytochrome P4501A1 (CYP1A1), and prostaglandin synthetase (PGS) in the cytotoxicity and DNA damage induced by BaP in the human tracheobronchial epithelial cells (HBECs) using RNA interference strategy and metabolic enzyme inhibitors. Our results showed that in three epithelial cell lines (HBE, HTR-8/SVneo, and HaCat), BaP significantly upregulated 5-LOX protein expression. 15-LOX-2 expression also increased with increasing BaP concentration, but the change was less pronounced than that of 5-LOX. BaP caused significant cytotoxicity, DNA strand breaks, and 8-hydroxy-2'-deoxyguanosine formation in HBE, which was inhibited by 5-LOXshRNA, a specific inhibitor of 5-LOX (AA861), the CYP1A1 inhibitor α-naphthoflavone, and the PGS inhibitor naproxen. The protective effects of 5-LOXshRNA were stronger than AA861, naproxen and α-naphthoflavone. We conclude that BaP may be activated more by 5-LOX than by CYP1A1 and PGS to produce cytotoxicity and DNA damage in HBE.

Very important pharmacogenes polymorphism landscape and potential clinical relevance in the Chinese Mongolian.

PURPOSE: Our study genotyped pharmacogenes in 200 individuals from Inner Mongolia Autonomous Region, China. Aim to find distinct pharmacogenomic variations among the Mongolian population and to investigate the potential clinically operable gene-drug connection and genotype-phenotype correlation of differential variation in the Mongolian population. METHODS: We sampled 61 variations of 28 genes in PharmGKB and genotyped them using Agena MassARRAY Assay. We also obtained the allele frequency and genotype distribution data of 26 populations from the 1000 Genomes Project (1000G), and then conducted comparison and statistical analysis. RESULTS: After Bonferroni correction, there were significant genotype frequency distribution differences between the Mongolian and 26 populations: PTGS2 (rs20417), NAT2 (rs1801280, rs1799929, and rs1208), ALOX5(rs2115819), and CYP2D6 (rs1065852). It was also found that the KHV showed the smallest differences from the Mongolian and the GWD showed the largest differences. Furthermore, the differences in variants might be related to the risk of non-steroidal anti-inflammatory drug use, the slow acetylation phenotype, and other pharmacological effectiveness and toxicity in the Mongolian population. CONCLUSION: Our study demonstrates different pharmacogenomic variants in the Mongolian and fills the gaps in pharmacogenomic information of the Mongolian. Our analysis of VIPs variants in the Mongolian population may contribute to the development of safer treatment regimens and the use of personalized treatment approaches.

Knock-out of 5-lipoxygenase in overexpressing tumor cells-consequences on gene expression and cellular function.

5-Lipoxygenase (5-LO), the central enzyme in the biosynthesis of leukotrienes, is frequently expressed in human solid malignancies even though the enzyme is not present in the corresponding healthy tissues. There is little knowledge on the consequences of this expression for the tumor cells regarding gene expression and cellular function. We established a knockout (KO) of 5-LO in different cancer cell lines (HCT-116, HT-29, U-2 OS) and studied the consequences on global gene expression using next generation sequencing. Furthermore, cell viability, proliferation, migration and multicellular tumor spheroid (MCTS) formation were studied in these cells. Our results show that 5-LO influences the gene expression and cancer cell function in a cell type-dependent manner. The enzyme affected genes involved in cell adhesion, extracellular matrix formation, G protein signaling and cytoskeleton organization. Furthermore, absence of 5-LO elevated TGFß2 expression in HCT-116 cells while MCP-1, fractalkine and platelet-derived growth factor expression was attenuated in U-2 OS cells suggesting that tumor cell-derived 5-LO shapes the tumor microenvironment. In line with the gene expression data, KO of 5-LO had an impact on cell proliferation, motility and MCTS formation. Interestingly, pharmacological inhibition of 5-LO only partly mimicked the KO suggesting that also noncanonical functions are involved.

Diminished arachidonate 5-lipoxygenase perturbs phase separation and transcriptional response of Runx2 to reverse pathological ventricular remodeling.

BACKGROUND: Arachidonate 5-lipoxygenase (Alox5) belongs to a class of nonheme iron-containing dioxygenases involved in the catalysis of leukotriene biosynthesis. However, the effects of Alox5 itself on pathological cardiac remodeling and heart failure remain elusive. METHODS: The role of Alox5 in pathological cardiac remodeling was investigated by Alox5 genetic depletion, AAV9-mediated overexpression in cardiomyocytes, and a bone marrow (BM) transplantation approach. Neonatal rat cardiomyocytes were used to explore the effects of Alox5 in vitro. Molecular and signaling pathways were revealed by CUT &Tag, IP-MS, RNA sequencing and bioinformatic analyses. FINDINGS: Untargeted metabolomics showed that serum 5-HETE (a primary product of Alox5) levels were little changed in patients with cardiac hypertrophy, while Alox5 expression was significantly upregulated in murine hypertensive cardiac samples and human cardiac samples of hypertrophy, which prompted us to test whether high Alox5 levels under hypertensive stimuli were directly associated with pathologic myocardium in an enzymatic activity-independent manner. Herein, we revealed that Alox5 deficiency significantly ameliorated transverse aortic constriction (TAC)-induced hypertrophy. Cardiomyocyte-specific Alox5 depletion attenuated hypertensive ventricular remodeling. Conversely, cardiac-specifical Alox5 overexpression showed a pro-hypertrophic cardiac phenotype. Ablation of Alox5 in bone marrow-derived cells did not affect pathological cardiac remodeling and heart failure. Mechanically, Runx2 was identified as a target of Alox5. In this regard, Alox5 PEST domain could directly bind to Runx2 PTS domain, promoting nuclear localization of Runx2 in an enzymatic activity-independent manner, simultaneously contributed to liquid-liquid phase separation (LLPS) of Runx2 at specific domain in the nucleus and increased transcription of EGFR in cardiomyocytes. Runx2 depletion alleviated hypertrophy in Ang II-pretreated Alox5-overexpressing cardiomyocytes. INTERPRETATION: Overall, our study demonstrated that targeting Alox5 exerted a protective effect against cardiac remodeling and heart failure under hypertensive stimuli by disturbing LLPS of Runx2 and substantial reduction of EGFR transcription activation in cardiomyocytes. Our findings suggest that negative modulation of Alox5-Runx2 may provide a therapeutic approach against pathological cardiac remodeling and heart failure. FUNDING: National Natural Science Foundation of China.