Fluoride Induces Neurocytotoxicity by Disrupting Lysosomal Iron Metabolism and Membrane Permeability.

The detrimental effects of fluoride on neurotoxicity have been widely recorded, yet the detailed mechanisms underlying these effects remain unclear. This study explores lysosomal iron metabolism in fluoride-related neurotoxicity, with a focus on the Steap3/TRPML1 axis. Utilizing sodium fluoride (NaF)-treated human neuroblastoma (SH-SY5Y) and mouse hippocampal neuron (HT22) cell lines, our research demonstrates that NaF enhances the accumulation of ferrous ions (Fe2+) in these cells, disrupting lysosomal iron metabolism through the Steap3/TRPML1 axis. Notably, NaF exposure upregulated ACSL4 and downregulated GPX4, accompanied by reduced glutathione (GSH) levels and superoxide dismutase (SOD) activity and increased malondialdehyde (MDA) levels. These changes indicate increased vulnerability to ferroptosis within neuronal cells. The iron chelator deferoxamine (DFO) mitigates this disruption. DFO binds to lysosomal Fe2+ and inhibits the Steap3/TRPML1 axis, restoring normal lysosomal iron metabolism, preventing lysosomal membrane permeabilization (LMP), and reducing neuronal cell ferroptosis. Our findings suggest that interference in lysosomal iron metabolism may mitigate fluoride-induced neurotoxicity, underscoring the critical role of the Steap3/TRPML1 axis in this pathological process.

Exploiting the ferroaddiction of pancreatic cancer cells using Fe-doped nanoparticles.

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with poor survival rates. Here, we evaluated iron-doped hydroxyapatite (FeHA) as a potential nanomedicine-based approach to combat PDAC. FeHA, in combination with a sublethal dose of the glutathione peroxidase 4 (GPX4) inhibitor RSL3, was found to trigger ferroptosis in KRAS mutant PANC-1 cells, but not in BxPC3 cells, while sparing normal human cells (fibroblasts and peripheral blood mononuclear cells). These findings were recapitulated in 3D spheroids generated using PDAC cells harboring wild-type versus mutant KRAS. Moreover, ferroptosis induction by FeHA plus RSL3 was reversed by the knockdown of STEAP3, a metalloreductase responsible for converting Fe3+ to Fe2+. Taken together, our data show that FeHA is capable of triggering cancer cell death in a KRAS-selective, STEAP3-dependent manner in PDAC cells.

Molecular characterization of STEAP3 in lung squamous cell carcinoma: Regulating EGFR to affect cell proliferation and ferroptosis.

Six-transmembrane epithelial antigen of the prostate 3 (STEAP3) has been reported to play a regulatory role in various types of cancers. However, its involvement in lung squamous cell carcinoma (LUSC) remains understudied. Here, we aimed to explore the biological functions and underlying mechanisms of STEAP3 in LUSC. Intersection genes associated with LUSC and ferroptosis were analyzed using the Venn method, STRING, GEPIA and UALCAN databases. The expression of STEAP3 was detected by qPCR and western blotting assay. Cell proliferation and viability were determined using the cell counting kit-8 assay and EDU staining. Oxidative stress and lipid peroxidation were measured by corresponding kits and DCFH-DA staining. Ferroptosis was evaluated by Phen Green SK and Western blot assay. The correlation between STEAP3 and EGFR was predicted by the TIMER and starBase database. Co-immunoprecipitation was conducted to verify the binding of STEAP3 and EGFR. The data demonstrated a significant upregulation of STEAP3 expression in LUSC cell lines. Silencing of STEAP3 suppressed H2170 cell viability and proliferation while promoting oxidative stress and lipid peroxidation through increased levels of MDA and ROS, as well as inhibited SOD activity. In addition, knockdown of STEAP3 induced ferroptosis through the regulation of ferroptosis-related proteins. Moreover, the binding between STEAP3 and EGFR was predicted and confirmed in LUSC. EGFR overexpression reversed the effects of STEAP3 silencing on H2170 cell viability, proliferation, oxidative stress, and ferroptosis. To summarize, the inhibition of STEAP3/EGFR may serve as a promising therapeutic target for LUSC treatment, as it can suppress LUSC proliferation and promote lipid peroxidation and ferroptosis.

STEAP3 is a prognostic biomarker that promotes glioma progression by regulating immune microenvironment and PI3K-AKT pathway.

BACKGROUND: STEAP3 is a metal reductase located on the plasma membrane close to the nucleus and vesicles. Despite numerous studies indicating the involvement of STEAP3 in tumor advancement, the prognostic value of STEAP3 in glioma and the related mechanisms have not been fully investigated. METHODS: Initially, we examined the correlation between STEAP3 expression and the survival rate in various glioma datasets. To assess the prognostic capability of STEAP3 for one-year, three-year, and five-year survival, we created receiver operating characteristic (ROC) curves and nomograms. Additionally, an investigation was carried out to examine the mechanisms that contribute to the involvement of STEAP3 in gliomas, including immune and enrichment analysis. To confirm the expression of STEAP3 in LGG and GBM, tumor tissue samples were gathered, and cell experiments were conducted to explore the impacts of STEAP3. The function of STEAP3 in the tumor immune microenvironment was assessed using the M2 macrophage infiltration assay. RESULTS: We found that STEAP3 expressed differently in group with different age, tumor grade IDH and 1p19q status. The analysis of survival illustrated that glioma patients with high level of STEAP3 experienced shorter survival durations, especially for IDH-mutant astrocytoma. Cox analysis demonstrated that STEAP3 had potential to act as an independent prognostic factor for glioma. The predictive value of STEAP3 for glioma prognosis was demonstrated by ROC curves and nomogram. Immune analysis showed that STEAP3 may lead to a suppressive immune microenvironment through the control of immunosuppressive cell infiltration and Cancer-Immunity Cycle. Combining enrichment analysis and cell experiments, we discovered that STEAP3 can promote glioma progression through regulation of PI3K-AKT pathway and M2 macrophage infiltration. CONCLUSION: STEAP3 plays significant roles in the advancement of glioma by regulating immune microenvironment and PI3K-AKT pathway. It has the potential to serve as a therapy target for glioma.

Research of STEAP3 interaction with Rab7A and RACK1 to modulate the MAPK and JAK/STAT signaling in Osteoarthritis.

Osteoarthritis (OA) is a degenerative joint disease characterized by cartilage degradation and inflammation. The molecular mechanisms underlying OA progression remain incompletely understood. In this study, we investigated the role of STEAP3 (Six Transmembrane Epithelial Antigen of the Prostate 3) in the development of OA. Our results demonstrated that STEAP3 was upregulated in OA cartilage tissues and contributes to the progression of the disease. To elucidate the mechanism, we employed transcriptomic and interaction proteomics analysis, and identified dysregulated genes and pathways associated with STEAP3 overexpression. Specifically, we found that STEAP3 interacted with Rab7A, a protein involved in intracellular trafficking and autophagy, and suppressed its activity. In addition, STEAP3 interacted with activated C kinase 1 (RACK1) and enhanced its activity. Furthermore, our data indicated that the suppression of Rab7A activity by STEAP3 promoted the activation of receptor tyrosine kinases (RTKs) and the promoting effects of RACK1 by STEAP3, both of which in turn activated the MAPK and JAK/STAT signaling pathways. In conclusion, our findings highlighted the role of STEAP3 in promoting OA progression. By inhibiting Rab7A activity and promoting RACK1 activity, STEAP3 enhanced inflammation through the activation of RTKs and subsequent activation of the MAPK and JAK/STAT signaling pathways. Targeting STEAP3 may provide a potential therapeutic strategy for the treatment of OA by modulating these interconnected pathways.

Chronic cadmium exposure triggered ferroptosis by perturbing the STEAP3-mediated glutathione redox balance linked to altered metabolomic signatures in humans.

Cadmium (Cd), a predominant environmental pollutant, is a canonical toxicant that acts on the kidneys. However, the nephrotoxic effect and underlying mechanism activated by chronic exposure to Cd remain unclear. In the present study, male mice (C57BL/6J, 8 weeks) were treated with 0.6 mg/L cadmium chloride (CdCl2) administered orally for 6 months, and tubular epithelial cells (TCMK-1 cells) were treated with low-dose (1, 2, and 3 µM) CdCl2 for 72 h (h). Our study results revealed that environmental Cd exposure triggered ferroptosis and renal dysfunction. Spatially resolved metabolomics enabled delineation of metabolic profiles and visualization of the disruption to glutathione homeostasis related to ferroptosis in mouse kidneys. Multiomics analysis revealed that chronic Cd exposure induced glutathione redox imbalance that depended on STEAP3-driven lysosomal iron overload. In particular, glutathione metabolic reprogramming linked to ferroptosis emerged as a metabolic hallmark in the blood of Cd-exposed workers. In conclusion, this study provides the first evidence indicating that chronic Cd exposure triggers ferroptosis and renal dysfunction that depend on STEAP3-mediated glutathione redox imbalance, greatly increasing our understanding of the metabolic reprogramming induced by Cd exposure in the kidneys and providing novel clues linking chronic Cd exposure to nephrotoxicity.

Bioinformatics analysis and prediction of Alzheimer's disease and alcohol dependence based on Ferroptosis-related genes.

Background: Alzheimer's disease (AD) is a neurodegenerative disease whose origins have not been universally accepted. Numerous studies have demonstrated the relationship between AD and alcohol dependence; however, few studies have combined the origins of AD, alcohol dependence, and programmed cell death (PCD) to analyze the mechanistic relationship between the development of this pair of diseases. We demonstrated in previous studies the relationship between psychiatric disorders and PCD, and in the same concerning neurodegeneration-related AD, we found an interesting link with the Ferroptosis pathway. In the present study, we explored the bioinformatic interactions between AD, alcohol dependence, and Ferroptosis and tried to elucidate and predict the development of AD from this aspect. Methods: We selected the Alzheimer's disease dataset GSE118553 and alcohol dependence dataset GSE44456 from the Gene Expression Omnibus (GEO) database. Ferroptosis-related genes were gathered through Gene Set Enrichment Analysis (GSEA), Kyoto Encyclopedia of Genes and Genomes (KEGG), and relevant literature, resulting in a total of 88 related genes. For the AD and alcohol dependence datasets, we conducted Limma analysis to identify differentially expressed genes (DEGs) and performed functional enrichment analysis on the intersection set. Furthermore, we used ferroptosis-related genes and the DEGs to perform machine learning crossover analysis, employing Least Absolute Shrinkage and Selection Operator (LASSO) regression to identify candidate immune-related central genes. This analysis was also used to construct protein-protein interaction networks (PPI) and artificial neural networks (ANN), as well as to plot receiver operating characteristic (ROC) curves for diagnosing AD and alcohol dependence. We analyzed immune cell infiltration to explore the role of immune cell dysregulation in AD. Subsequently, we conducted consensus clustering analysis of AD using three relevant candidate gene models and examined the immune microenvironment and functional pathways between different subgroups. Finally, we generated a network of gene-gene interactions and miRNA-gene interactions using Networkanalyst. Results: The crossover of AD and alcohol dependence DEG contains 278 genes, and functional enrichment analysis showed that both AD and alcohol dependence were strongly correlated with Ferroptosis, and then crossed them with Ferroptosis-related genes to obtain seven genes. Three candidate genes were finally identified by machine learning to build a diagnostic prediction model. After validation by ANN and PPI analysis, ROC curves were plotted to assess the diagnostic value of AD and alcohol dependence. The results showed a high diagnostic value of the predictive model. In the immune infiltration analysis, functional metabolism and immune microenvironment of AD patients were significantly associated with Ferroptosis. Finally, analysis of target genes and miRNA-gene interaction networks showed that hsa-mir-34a-5p and has-mir-106b-5p could simultaneously regulate the expression of both CYBB and ACSL4. Conclusion: We obtained a diagnostic prediction model with good effect by comprehensive analysis, and validation of ROC in AD and alcohol dependence data sets showed good diagnostic, predictive value for both AD (AUC 0. 75, CI 0.91-0.60), and alcohol dependence (AUC 0.81, CI 0.95-0.68). In the consensus clustering grouping, we identified variability in the metabolic and immune microenvironment between subgroups as a likely cause of the different prognosis, which was all related to Ferroptosis function. Finally, we discovered that hsa-mir-34a-5p and has-mir-106b-5p could simultaneously regulate the expression of both CYBB and ACSL4.

Identification of STEAP3-based molecular subtype and risk model in ovarian cancer.

BACKGROUND: Ovarian cancer (OC) is one of the most common malignancies in women. It has a poor prognosis owing to its recurrence and metastasis. Unfortunately, reliable markers for early diagnosis and prognosis of OC are lacking. Our research aimed to investigate the value of the six-transmembrane epithelial antigen of prostate family member 3 (STEAP3) as a prognostic predictor and therapeutic target in OC using bioinformatics analysis. METHODS: STEAP3 expression and clinical data were acquired from The Cancer Genome Atlas (TCGA), Genotype-Tissue Expression (GTEx), and Gene Expression Omnibus (GEO). Unsupervised clustering was used to identify molecular subtypes. Prognosis, tumor immune microenvironment (TIME), stemness indexes, and functional enrichment analysis were compared between two definite clusters. Through the least absolute shrinkage and selection operator (LASSO) regression analysis, a STEAP3-based risk model was developed, and the predictive effectiveness of this signature was confirmed using GEO datasets. A nomogram was used to predict the survival possibility of patients. Additionally, TIME, tumor immune dysfunction and exclusion (TIDE), stemness indexes, somatic mutations, and drug sensitivity were evaluated in different risk groups with OC. STEAP3 protein expression was detected using immunohistochemistry (IHC). RESULTS: STEAP3 displayed marked overexpression in OC. STEAP3 is an independent risk factor for OC. Based on the mRNA levels of STEAP3-related genes (SRGs), two distinct clusters were identified. Patients in the cluster 2 (C2) subgroup had a considerably worse prognosis, higher immune cell infiltration, and lower stemness scores. Pathways involved in tumorigenesis and immunity were highly enriched in the C2 subgroup. A prognostic model based on 13 SRGs was further developed. Kaplan-Meier analysis indicated that the overall survival (OS) of high-risk patients was poor. The risk score was significantly associated with TIME, TIDE, stemness indexes, tumor mutation burden (TMB), immunotherapy response, and drug sensitivity. Finally, IHC revealed that STEAP3 protein expression was noticeably elevated in OC, and overexpression of STEAP3 predicted poor OS and relapse-free survival (RFS) of patients. CONCLUSION: In summary, this study revealed that STEAP3 reliably predicts patient prognosis and provides novel ideas for OC immunotherapy.

Six-transmembrane epithelial antigen of prostate 3 (STEAP3) is a potential prognostic biomarker in clear cell renal cell carcinoma that correlates with M2 macrophage infiltration and epithelial-mesenchymal.

BACKGROUND: The six-transmembrane epithelial antigen of the prostate 3 (STEAP3) is a metalloreductase, which is essential for iron uptake. Existing literature has shown that STEAP3 may perform an important role in the onset and progression of tumors. Nonetheless, a complete pan-cancer investigation of the prognostic significance and immune properties of STEAP3 is currently unavailable. AIMS: As part of our investigation into the possible functions of STEAP3 in malignancies, we conducted a comprehensive analysis to examine the prognostic value and immune features of STEAP3 in human pan-cancer. METHODS AND RESULTS: R and Cytoscape programs were applied to analyze and visualize the data. The expression of STEAP3 in both cell lines and tissues was measured utilizing a variety of approaches. Using the shRNA knockdown technique, we tested the viability of the A498 and 786-O cell lines and validated their functions. Both CCK-8 and transwell assays were conducted to estimate cell proliferation and invasion. The expression of STEAP3 was substantially elevated and was shown to be linked to prognosis in the majority of malignancies, notably in clear cell renal cell carcinoma (ccRCC). In addition, the expression of STEAP3 was shown to have a strong correlation with immune infiltrates, which in turn triggered the recruitment and polarization of M2 macrophages in ccRCC. The protein STEAP3 shows promise as a predictor of responses to immune-checkpoint blockade (ICB) therapy. Positive links between STEAP3 and the epithelial-mesenchymal transition (EMT), the p53 pathway, and the immune-associated pathways were also found in the enrichment analysis. Our results illustrated that the STEAP3 expression level was substantially elevated in ccRCC tissues and suggested that it could stimulate EMT in ccRCC by downregulating CDH1. CONCLUSION: In a diverse range of cancers, STEAP3 might serve as a biomarker for determining the prognosis as well as a predictor of immunotherapy responsiveness. STEAP3 is a novel biological marker for determining prognosis, and it also performs a remarkable function in the promotion of tumor growth in ccRCC by enhancing invasion and EMT, as well as by triggering the recruitment and polarization of M2 macrophages.

High expression of six-transmembrane epithelial antigen of prostate 3 promotes the migration and invasion and predicts unfavorable prognosis in glioma.

Recent studies have suggested that ferroptosis, a form of iron-dependent regulated cell death, might play essential roles in tumor initiation and progression. Six-transmembrane epithelial antigen of prostate 3 (STEAP3) is a ferrireductase involved in the regulation of intracellular iron homeostasis. However, the clinical significance and biological function of STEAP3 in human cancers remain poorly understood. Through a comprehensive bioinformatics analysis, we found that STEAP3 mRNA and protein expression were up-regulated in GBM, LUAD, and UCEC, and down-regulated in LIHC. Survival analysis indicated that STEAP3 had prognostic significance only in glioma. Multivariate Cox regression analysis revealed that high STEPA3 expression was correlated with poor prognosis. STEAP3 expression was significantly negatively correlated with promoter methylation level, and patients with lower STEAP3 methylation level had worse prognosis than those with higher STEAP3 methylation level. Single-cell functional state atlas showed that STEAP3 regulated epithelial-to-mesenchymal transition (EMT) in GBM. Furthermore, the results of wound healing and transwell invasion assays demonstrated that knocking down STEAP3 inhibited the migration and invasion of T98G and U251 cells. Functional enrichment analysis suggested that genes co-expressed with STEAP3 mainly participated in inflammation and immune-related pathways. Immunological analysis revealed that STEAP3 expression was significantly correlated with immune infiltration cells, including macrophages and neutrophils, especially the M2 macrophages. Individuals with low STEAP3 expression were more likely to respond to immunotherapy than those with high STEAP3 expression. These results suggest that STEAP3 promotes glioma progression and highlight its pivotal role in regulating immune microenvironment.

Upregulation of the ferroptosis-related STEAP3 gene is a specific predictor of poor triple-negative breast cancer patient outcomes.

Objective: This study was designed to assess ferroptosis regulator gene (FRG) expression patterns in patients with TNBC based on data derived from The Cancer Genome Atlas (TCGA). Further, it was utilized to establish a TNBC FRG signature, after which the association between this signature and the tumor immune microenvironment (TIME) composition was assessed, and relevant prognostic factors were explored. Methods: The TCGA database was used to obtain RNA expression datasets and clinical information about 190 TNBC patients, after which a prognostic TNBC-related FRG signature was established using a least absolute shrinkage and selection operator (LASSO) Cox regression approach. These results were validated with separate data from the Gene Expression Omnibus (GEO). The TNBC-specific prognostic gene was identified via this method. The STEAP3 was then validated through Western immunoblotting, immunohistochemical staining, and quantitative real-time polymerase chain reaction (RT-qPCR) analyses of clinical tissue samples and TNBC cell lines. Chemotherapy interactions and predicted drug sensitivity studies were investigated to learn more about the potential clinical relevance of these observations. Results: These data revealed that 87 FRGs were differentially expressed when comparing TNBC tumors and healthy tissue samples (87/259, 33.59%). Seven of these genes (CA9, CISD1, STEAP3, HMOX1, DUSP1, TAZ, HBA1) are significantly related to the overall survival of TNBC patients. Kaplan-Meier analyses and established FRG signatures and nomograms identified CISD1 and STEAP3 genes of prognostic relevance. Prognostic Risk Score values were positively correlated with the infiltration of CD4+ T cells (p = 0.001) and myeloid dendritic cells (p =0.004). Further evidence showed that STEAP3 was strongly and specifically associated with TNBC patient OS (P<0.05). The results above were confirmed by additional examinations of STEAP3 expression changes in TNBC patient samples and cell lines. High STEAP3 levels were negatively correlated with half-maximal inhibitory concentration (IC50) values for GSK1904529A (IGF1R inhibitor), AS601245 (JNK inhibitor), XMD8-85 (Erk5 inhibitor), Gefitinib, Sorafenib, and 5-Fluorouracil (P < 0.05) in patients with TNBC based on information derived from the TCGA-TNBC dataset. Conclusion: In the present study, a novel FRG model was developed and used to forecast the prognosis of TNBC patients accurately. Furthermore, it was discovered that STEAP3 was highly overexpressed in people with TNBC and associated with overall survival rates, laying the groundwork for the eventually targeted therapy of individuals with this form of cancer.

Six-Transmembrane Epithelial Antigen of Prostate 3 Promotes Hepatic Insulin Resistance and Steatosis.

Nonalcoholic fatty liver disease (NAFLD) is a clinicopathological syndrome characterized by excessive deposition of fatty acids in the liver. Further deterioration leads to nonalcoholic steatohepatitis, cirrhosis, and hepatocellular carcinoma, creating a heavy burden on human health and the social economy. Currently, there are no effective and specific drugs for the treatment of NAFLD. Therefore, it is important to further investigate the pathogenesis of NAFLD and explore effective therapeutic targets for the prevention and treatment of the disease. Six-transmembrane epithelial antigen of prostate 3 (STEAP3), a STEAP family protein, is a metalloreductase. Studies have shown that it can participate in the regulation of liver ischemia-reperfusion injury, hepatocellular carcinoma, myocardial hypertrophy, and other diseases. In this study, we found that the expression of STEAP3 is upregulated in NAFLD. Deletion of STEAP3 inhibits the development of NAFLD in vivo and in vitro, whereas its overexpression promotes palmitic acid/oleic acid stimulation-induced lipid deposition in hepatocytes. Mechanistically, it interacts with transforming growth factor beta-activated kinase 1 (TAK1) to regulate the progression of NAFLD by promoting TAK1 phosphorylation and activating the TAK1-c-Jun N-terminal kinase/p38 signaling pathway. Taken together, our results provide further insight into the involvement of STEAP3 in liver pathology.

STEAP3 can predict the prognosis and shape the tumor microenvironment of clear cell renal cell carcinoma.

Clear cell renal cell carcinoma (ccRCC) is a common malignant tumor of the urinary system characterized by poor prognosis and difficult treatment. It has been reported that iron metabolism dysregulation is a common phenomenon in ccRCC and is closely related to the process of ccRCC. But still now, the exact function and underlying mechanisms of iron metabolism dysregulation in ccRCC have not been fully elucidated. In this study, we comprehensively investigated the prognostic value and potential role of STEAP3 (an iron metabolism-related gene) in ccRCC. STEAP3 is significantly up-regulated in ccRCC. High STEAP3 expression is associated with gender, hemoglobin level, pathological grade, tumor stage and significantly predicts an unfavorable prognosis of ccRCC patients. Functional enrichment analysis and evaluation of the tumor microenvironment indicated that STEAP3 was involved in the remodeling of tumor extracellular matrix and the shaping of an immune-suppressive tumor microenvironment to promote tumor metastasis and evade immune killing. Besides, the expression of STEAP3 is also associated with the expression of various immune checkpoint molecules and the IC50 of targeted drugs. Finally, we verified STEAP3 by RT-qPCR and IHC staining. In conclusion, we found that STEAP3 can serve as a candidate prognostic biomarker for ccRCC, and targeting STEAP3 and its biological processes may provide new references for the individualized treatment of ccRCC.

Hypoxia-induced lncRNA STEAP3-AS1 activates Wnt/ß-catenin signaling to promote colorectal cancer progression by preventing m6A-mediated degradation of STEAP3 mRNA.

BACKGROUND: Hypoxia, a typical hallmark of solid tumors, exhibits an essential role in the progression of colorectal cancer (CRC), in which the dysregulation of long non-coding RNAs (lncRNAs) is frequently observed. However, the underlying mechanisms are not clearly defined. METHODS: The TCGA database was analyzed to identify differential lncRNA expression involved in hypoxia-induced CRC progression. qRT-PCR was conducted to validate the upregulation of lncRNA STEAP3-AS1 in CRC cell lines and tumor-bearing mouse and zebrafish models under hypoxia. ChIP-qRT-PCR was used to detect the transcriptional activation of STEAP3-AS1 mediated by HIF-1α. RNA-seq, fluorescent in situ hybridization, RNA pulldown, RNA immunoprecipitation, co-immunoprecipitation, immunofluorescence and immunoblot experiments were used to ascertain the involved mechanisms. Functional assays were performed in both in vitro and in vivo models to investigate the regulatory role of STEAP3-AS1/STEAP3/Wnt/ß-catenin axis in CRC proliferation and metastasis. RESULTS: Here, we identified a hypoxia-induced antisense lncRNA STEAP3-AS1 that was highly expressed in clinical CRC tissues and positively correlated with poor prognosis of CRC patients. Upregulation of lncRNA STEAP3-AS1, which was induced by HIF-1α-mediated transcriptional activation, facilitated the proliferation and metastasis of CRC cells both in vitro and in vivo. Mechanistically, STEAP3-AS1 interacted competitively with the YTH domain-containing family protein 2 (YTHDF2), a N6-methyladenosine (m6A) reader, leading to the disassociation of YTHDF2 with STEAP3 mRNA. This effect protected STEAP3 mRNA from m6A-mediated degradation, enabling the high expression of STEAP3 protein and subsequent production of cellular ferrous iron (Fe2+). Increased Fe2+ levels elevated Ser 9 phosphorylation of glycogen synthase kinase 3 beta (GSK3ß) and inhibited its kinase activity, thus releasing ß-catenin for nuclear translocation and subsequent activation of Wnt signaling to support CRC progression. CONCLUSIONS: Taken together, our study highlights the mechanisms of lncRNA STEAP3-AS1 in facilitating CRC progression involving the STEAP3-AS1/STEAP3/Wnt/ß-catenin axis, which may provide novel diagnostic biomarkers or therapeutic targets to benefit CRC treatment. Hypoxia-induced HIF-1α transcriptionally upregulates the expression of lncRNA STEAP3-AS1, which interacts competitively with YTHDF2, thus upregulating mRNA stability of STEAP3 and consequent STEAP3 protein expression. The enhanced STEAP3 expression results in production of cellular ferrous iron (Fe2+), which induces the Ser 9 phosphorylation and inactivation of GSK3ß, releasing ß-catenin for nuclear translocation and contributing to subsequent activation of Wnt signaling to promote CRC progression.

Label-free quantitative proteomics reveals the Steap3-Gm2a axis inhibiting the phagosomal escape of Listeria monocytogenes.

As a pathogenic microorganism, Listeria monocytogenes is widely used in the research of bacterial pathogenesis and host defense. The phagosomal escape of L. monocytogenes is essential for its replication in the cytoplasm of the host. Here, we reported that the protein abundance of the Six-transmembrane epithelial antigen of the prostate 3 (Steap3) was decreased upon L. monocytogenes infection compared to uninfected cells in macrophages. However, the decreased Steap3 abundance was not regulated by the host but was caused by LLO secreted by L. monocytogenes. Functional experiments showed that deletion of Steap3 facilitated entry of L. monocytogenes from the phagosome into the cytoplasm. Then, the comprehensive proteomic analysis revealed that the deletion of Steap3 could affect the proteins abundance of the lysosomal signaling pathway in macrophages. Among these proteins affected by Steap3, we discovered that only the Ganglioside GM2 activator (Gm2a) inhibited the phagosomal escape of L. monocytogenes as Steap3. In summary, we found that the Steap3-Gm2a axis could restrict the phagosomal escape of L. monocytogenes and serve the potential molecular drug targets for antibacterial treatment.

miR-124-3p delivered by exosomes from heme oxygenase-1 modified bone marrow mesenchymal stem cells inhibits ferroptosis to attenuate ischemia-reperfusion injury in steatotic grafts.

BACKGROUND: Steatotic livers tolerate ischemia-reperfusion injury (IRI) poorly, increasing the risk of organ dysfunction. Ferroptosis is considered the initiating factor of organ IRI. Heme oxygenase oxygen-1 (HO-1)-modified bone marrow mesenchymal stem cells (BMMSCs) (HO-1/BMMSCs) can reduce hepatic IRI; however, the role of ferroptosis in IRI of steatotic grafts and the effect of HO-1/BMMSCs-derived exosomes (HM-exos) on ferroptosis remain unknown. METHODS: A model of rat liver transplantation (LT) with a severe steatotic donor liver and a model of hypoxia and reoxygenation (H/R) of steatotic hepatocytes were established. Exosomes were obtained by differential centrifugation, and the differentially expressed genes (DEGs) in liver after HM-exo treatment were detected using RNA sequencing. The expression of ferroptosis markers was analyzed. microRNA (miRNA) sequencing was used to analyze the miRNA profiles in HM-exos. RESULTS: We verified the effect of a candidate miRNA on ferroptosis of H/R treated hepatocytes, and observed the effect of exosomes knockout of the candidate miRNA on hepatocytes ferroptosis. In vitro, HM-exo treatment reduced the IRI in steatotic grafts, and enrichment analysis of DEGs suggested that HM-exos were involved in the regulation of the ferroptosis pathway. In vitro, inhibition of ferroptosis by HM-exos reduced hepatocyte injury. HM-exos contained more abundant miR-124-3p, which reduced ferroptosis of H/R-treated cells by inhibiting prostate six transmembrane epithelial antigen 3 (STEAP3), while overexpression of Steap3 reversed the effect of mir-124-3p. In addition, HM-exos from cell knocked out for miR-124-3p showed a weakened inhibitory effect on ferroptosis. Similarly, HM-exo treatment increased the content of miR-124-3p in grafts, while decreasing the level of STEAP3 and reducing the degree of hepatic ferroptosis. CONCLUSION: Ferroptosis is involved in the IRI during LT with a severe steatotic donor liver. miR-124-3p in HM-exos downregulates Steap3 expression to inhibit ferroptosis, thereby attenuating graft IRI, which might be a promising strategy to treat IRI in steatotic grafts.

STEAP3 Affects Ferroptosis and Progression of Renal Cell Carcinoma Through the p53/xCT Pathway.

Renal cell carcinoma is particularly sensitive to ferroptosis, an iron-dependent non-apoptotic form of cell death. This mechanism does not require activation of caspase or the participation of other apoptotic effector molecules (such as BAX or BAK), nor is it accompanied by the morphological characteristics or biochemical processes of apoptosis. The STEAP3 gene was found because it promotes tumor apoptosis in prostate cancer, but its role in renal cell carcinoma has not been studied in depth. Through real-time quantitative polymerase chain reaction, we found that the expression of the STEAP3 gene was upregulated in renal cell carcinoma tissue samples and cell lines, and it was found to be highly expressed in renal cell carcinoma tissue through immunohistochemistry. This upregulation is related to poor survival and prognosis of patients. We used erastin, a ferroptosis inducer, found that renal cell carcinoma became more susceptible to ferroptosis after knocking down STEAP3. The results indicate that renal cell carcinoma cell lines with knocked down STEAP3 expression are more sensitive to ferroptosis, and this effect occurs through the p53/xCT pathway. In summary, our research helps to identify new biomarkers and provides new targets for the treatment of renal cell carcinoma.

Whole exome sequencing identifies the potential role of genes involved in p53 pathway in Nasopharyngeal Carcinoma from Northeast India.

Nasopharyngeal Carcinoma (NPC) found to be dependent on geographical and racial variation and is more prevalent in Northeast (NE) India. WES-based study was conducted in three states (tribes); Nagaland (Naga), Mizoram (Mizo) and Manipur (Manipuri), which provided an overview of germline variants involved inthemajor signaling pathways. Validation and recurrence assessment of WES data confirmed the risk effect of STEAP3_rs138941861 and JAG1_rs2273059, and the protective role of PARP4_rs17080653 and TGFBR1_rs11568778 variants, where STEAP3_rs138941861conferring Arg290His substitution was the only exonic non-synonymous variant and to be located in proximity to the linking region between the transmembrane and oxidoreductasedomainsof STEAP3 protein, andaffectedits structural and functional dynamics by altering the Electrostatic Potential around this connecting region. Moreover, these significantly associated variants having deleterious effect were observed to have interactions in p53 signaling pathway which emphasizes the importance of this pathway in the causation of NPC.

Downregulated Ferroptosis-Related Gene STEAP3 as a Novel Diagnostic and Prognostic Target for Hepatocellular Carcinoma and Its Roles in Immune Regulation.

Ferroptosis, a distinct type of regulated cell death, has been reported to be involved in the tumorigenesis of liver hepatocellular carcinoma (LIHC). However, the precise functions and potential mechanisms of ferroptosis in LIHC were still poorly understood. Herein, we investigated the biological roles of ferroptosis-related gene STEAP3 in LIHC. STEAP3 was previously proved to serve a key regulator in ferroptosis via mediating the iron metabolism. Comprehensive bioinformatics from several databases revealed that STEAP3 was significantly downregulated in LIHC tissues and exhibited the favorable prognostic significance in LIHC patients. The downregulated STEAP3 was further confirmed in two LIHC cells Huh7 and MHCC97H using real-time PCR and western blot. And STEAP3 overexpression significantly inhibited the cell proliferation in Huh7 and MHCC97H cells. In addition, clinical data identified the relationship between STEAP3 expression and several clinicopathological parameters of LIHC patients, including histologic grade, alpha fetal protein (AFP) concentration, etc. Receiver operation characteristic (ROC) curve revealed STEAP3 as a potential diagnostic biomarker for LIHC patients. Moreover, the co-expression network of STEAP3 was explored to gain a better insight into its underlying signaling pathways. Finally, aberrant STEAP3 might participate in varieties of immune-associated signatures in LIHC pathogenesis, including immunostimulators, immunoinhibitors, chemokines, and chemokine receptors. Taken together, these findings could enhance our knowledge regarding the inhibitory roles and underlying biological significance of STEAP3 in LIHC tumorigenesis.

A risk stratification model based on four novel biomarkers predicts prognosis for patients with renal cell carcinoma.

BACKGROUND: Accurate prediction of the prognosis of RCC using a single biomarker is challenging due to the genetic heterogeneity of the disease. However, it is essential to develop an accurate system to allow better patient selection for optimal treatment strategies. ARL4C, ECT2, SOD2, and STEAP3 are novel molecular biomarkers identified in earlier studies as survival-related genes by comprehensive analyses of 43 primary RCC tissues and RCC cell lines. METHODS: To develop a prognostic model based on these multiple biomarkers, the expression of four biomarkers ARL4C, ECT2, SOD2, and STEAP3 in primary RCC tissue were semi-quantitatively investigated by immunohistochemical analysis in an independent cohort of 97 patients who underwent nephrectomy, and the clinical significance of these biomarkers were analyzed by survival analysis using Kaplan-Meier curves. The prognostic model was constructed by calculation of the contribution score to prognosis of each biomarker on Cox regression analysis, and its prognostic performance was validated. RESULTS: Patients whose tumors had high expression of the individual biomarkers had shorter cancer-specific survival (CSS) from the time of primary nephrectomy. The prognostic model based on four biomarkers segregated the patients into a high- and low-risk scored group according to defined cut-off value. This approach was more robust in predicting CSS compared to each single biomarker alone in the total of 97 patients with RCC. Especially in the 36 metastatic RCC patients, our prognostic model could more accurately predict early events within 2 years of diagnosis of metastasis. In addition, high risk-scored patients with particular strong SOD2 expression had a much worse prognosis in 25 patients with metastatic RCC who were treated with molecular targeting agents. CONCLUSIONS: Our findings indicate that a prognostic model based on four novel biomarkers provides valuable data for prediction of clinical prognosis and useful information for considering the follow-up conditions and therapeutic strategies for patients with primary and metastatic RCC.