Fusion of the Genes for Interferon Regulatory Factor 2 Binding Protein 2 (IRF2BP2) and Caudal Type Homeobox 1 (CDX1) in a Chondrogenic Tumor.

BACKGROUND/AIM: Chondrogenic tumors are benign, intermediate or malignant neoplasms showing cartilaginous differentiation. In 2012, we reported a mesenchymal chondrosarcoma carrying a t(1;5)(q42;q32) leading to an IRF2BP2::CDX1 fusion gene. Here, we report a second chondrogenic tumor carrying an IRF2BP2::CDX1 chimera. CASE REPORT: Radiological examination of a 41 years old woman showed an osteolytic lesion in the os pubis with a large soft tissue component. Examination of a core needle biopsy led to the diagnosis chondromyxoid fibroma, and the patient was treated with curettage. Microscopic examination of the specimen showed a tumor tissue in which a pink-bluish background matrix was studded with small spindled to stellate cells without atypia, fitting well the chondromyxoid fibroma diagnosis. Focally, a more cartilage-like appearance was observed with cells lying in lacunae and areas with calcification. G-banding analysis of short-term cultured tumor cells yielded the karyotype 46,XX,der(1)inv(1)(p33~34q42) add(1)(p32)?ins(1;?)(q42;?),del(5)(q31),der(5)t(1;5)(q42;q35)[12]/46,XX[3]. RT-PCR together with Sanger sequencing showed the presence of two IRF2BP2::CDX1 chimeric transcripts in which exon 1 of the IRF2BP2 reference sequence NM_182972.3 or NM_001077397.1 was fused to exon 2 of CDX1. Both chimeras were predicted to code for proteins containing the zinc finger domain of IRF2BP2 and homeobox domain of CDX1. CONCLUSION: IRF2BP2::CDX1 chimera is recurrent in chondrogenic tumors. The data are still too sparse to conclude whether it is a hallmark of benign or malignant tumors.

Long noncoding RNA SENCR facilitates the progression of acute myeloid leukemia through the miR-4731-5p/IRF2 pathway.

BACKGROUND: Acute myeloid leukemia (AML) is a type of hematological tumor caused by malignant clone hematopoietic stem cells. The relationship between lncRNAs and tumor occurrence and progression has been gaining attention. Research has shown that Smooth muscle and endothelial cell-enriched migration/differentiation-associated lncRNA (SENCR) is abnormally expressed in various diseases, whereas its role in AML is still poorly understood. METHODS: The expression of SENCR, microRNA-4731-5p (miR-4731-5p) and Interferon regulatory factor 2 (IRF2) were measured using qRT-PCR. The proliferation, cycle and apoptosis of AML cells with or without knockdown of SENCR were detected by CCK-8 assay, EdU assay, flow cytometry, western blotting and TUNEL assay, respectively. Consistently, SENCR knockdown was impaired the AML progression in immunodeficient mice. In addition, the binding of miR-4731-5p to SENCR or IRF2 was confirmed by luciferase reporter genes assay. Finally, rescue experiments were conducted to confirm the role of SENCR/miR-4731-5p/IRF2 axis in AML. RESULTS: SENCR is highly expressed in AML patients and cell lines. The patients with high SENCR expression had poorer prognosis compared with those with low SENCR expression. Interestingly, knockdown of SENCR inhibits the growth of AML cells. Further results demonstrated that the reduction of SENCR slows the progression of AML in vivo. SENCR could function as a competing endogenous RNA (ceRNA) to negatively regulate miR-4731-5p in AML cells. Furthermore, IRF2 was validated as a direct target gene of miR-4731-5p in AML cells. CONCLUSIONS: Our findings underscore the important role of SENCR in regulating the malignant phenotype of AML cells by targeting the miR-4731-5p/IRF2 axis.

Basal and immune-responsive transcript expression of two Atlantic salmon interferon regulatory factor 2 (irf2) paralogues.

Atlantic salmon (Salmo salar) is one of the most economically important aquaculture species globally. However, disease has become a prevalent threat to this industry. A thorough understanding of the genes and molecular pathways involved in the immune responses of Atlantic salmon is imperative for selective breeding of disease-resistant broodstock, as well as developing new diets and vaccines to mitigate the impact of disease. Members of the interferon regulatory factor (IRF) family of transcription factors play roles in the induction of interferons and other cytokines involved in host immune responses to intracellular and parasitic pathogens. IRF family members also play diverse roles in other biological processes, such as stress response, reproduction and development. The current study focused on one member of the IRF family: interferon regulatory factor 2 (irf2). As previously shown, due to the genome duplication that occurred ∼80 million years ago in the salmonid lineage, there are two irf2 paralogues in the Atlantic salmon genome. In silico analyses at the cDNA and deduced amino acid levels were conducted followed by phylogenetic tree construction with IRF2 amino acid sequences from various ray-finned fishes, cartilaginous fish and tetrapods. qPCR was then used to analyze paralogue-specific irf2 constitutive expression across 17 adult tissues, as well as responses to the viral mimic pIC (i.e., synthetic double-stranded RNA analog) in cultured macrophage-like cells (in vitro) and to infection with the Gram-negative bacterium Moritella viscosa in skin samples (in vivo). The qPCR studies showed sex- and paralogue-specific differences in expression across tissues. For example, expression of both paralogues was higher in ovary than in testes; expression (considering both sexes together) was highest for irf2-1 in gonad and for irf2-2 in hindgut. Both irf2 paralogues were responsive to pIC stimulation, but varied in their induction level, with irf2-1 having an overall stronger response than irf2-2. Only one paralogue, irf2-2, was significantly responsive to M. viscosa infection. Differences in irf2-1 and irf2-2 transcript expression levels constitutively across tissues, and in response to pIC and M. viscosa, may suggest neo- or subfunctionalization of the duplicated genes. This novel information expands current knowledge and provides insight into how genome duplication events may impact host regulation of important immune markers.

IRF2 is required for development and functional maturation of human NK cells.

Natural killer (NK) cells are cytotoxic and cytokine-producing lymphocytes that play an important role in the first line of defense against malignant or virus-infected cells. A better understanding of the transcriptional regulation of human NK cell differentiation is crucial to improve the efficacy of NK cell-mediated immunotherapy for cancer treatment. Here, we studied the role of the transcription factor interferon regulatory factor (IRF) 2 in human NK cell differentiation by stable knockdown or overexpression in cord blood hematopoietic stem cells and investigated its effect on development and function of the NK cell progeny. IRF2 overexpression had limited effects in these processes, indicating that endogenous IRF2 expression levels are sufficient. However, IRF2 knockdown greatly reduced the cell numbers of all early differentiation stages, resulting in decimated NK cell numbers. This was not caused by increased apoptosis, but by decreased proliferation. Expression of IRF2 is also required for functional maturation of NK cells, as the remaining NK cells after silencing of IRF2 had a less mature phenotype and showed decreased cytotoxic potential, as well as a greatly reduced cytokine secretion. Thus, IRF2 plays an important role during development and functional maturation of human NK cells.

IRF2 integrates inflammatory signals to balance T cell exhaustion.

The transcription factor interferon regulatory factor 2 (IRF2) translates interferon signaling to regulate T cells. In this issue of Immunity, Lukhele et al. identify IRF2 in tumor-infiltrating T cells as a sensor for extrinsic signals that drives an exhaustion program.

The transcription factor IRF2 drives interferon-mediated CD8+ T cell exhaustion to restrict anti-tumor immunity.

Type I and II interferons (IFNs) stimulate pro-inflammatory programs that are critical for immune activation, but also induce immune-suppressive feedback circuits that impede control of cancer growth. Here, we sought to determine how these opposing programs are differentially induced. We demonstrated that the transcription factor interferon regulatory factor 2 (IRF2) was expressed by many immune cells in the tumor in response to sustained IFN signaling. CD8+ T cell-specific deletion of IRF2 prevented acquisition of the T cell exhaustion program within the tumor and instead enabled sustained effector functions that promoted long-term tumor control and increased responsiveness to immune checkpoint and adoptive cell therapies. The long-term tumor control by IRF2-deficient CD8+ T cells required continuous integration of both IFN-I and IFN-II signals. Thus, IRF2 is a foundational feedback molecule that redirects IFN signals to suppress T cell responses and represents a potential target to enhance cancer control.

Characterisation of the Circulating Transcriptomic Landscape in Inflammatory Bowel Disease Provides Evidence for Dysregulation of Multiple Transcription Factors Including NFE2, SPI1, CEBPB, and IRF2.

AIM: To assess the pathobiological and translational importance of whole-blood transcriptomic analysis in inflammatory bowel disease [IBD]. METHODS: We analysed whole-blood expression profiles from paired-end sequencing in a discovery cohort of 590 Europeans recruited across six countries in the IBD Character initiative (newly diagnosed patients with Crohn's disease [CD; n = 156], ulcerative colitis [UC; n = 167], and controls [n = 267]), exploring differential expression [DESeq2], co-expression networks [WGCNA], and transcription factor involvement [EPEE, ChEA, DoRothEA]. Findings were validated by analysis of an independent replication cohort [99 CD, 100 UC, 95 controls]. In the discovery cohort, we also defined baseline expression correlates of future treatment escalation using cross-validated elastic-net and random forest modelling, along with a pragmatic ratio detection procedure. RESULTS: Disease-specific transcriptomes were defined in IBD [8697 transcripts], CD [7152], and UC [8521], with the most highly significant changes in single genes, including CD177 (log2-fold change [LFC] = 4.63, p = 4.05 × 10-118), MCEMP1 [LFC = 2.45, p = 7.37 × 10-109], and S100A12 [LFC = 2.31, p = 2.15 × 10-93]. Significantly over-represented pathways included IL-1 [p = 1.58 × 10-11], IL-4, and IL-13 [p = 8.96 × 10-9]. Highly concordant results were obtained using multiple regulatory activity inference tools applied to the discovery and replication cohorts. These analyses demonstrated central roles in IBD for the transcription factors NFE2, SPI1 [PU.1], CEBPB, and IRF2, all regulators of cytokine signalling, based on a consistent signal across cohorts and transcription factor ranking methods. A number of simple transcriptome-based models were associated with the need for treatment escalation, including the binary CLEC5A/CDH2 expression ratio in UC (hazard ratio = 23.4, 95% confidence interval [CI] 5.3-102.0). CONCLUSIONS: Transcriptomic analysis has allowed for a detailed characterisation of IBD pathobiology, with important potential translational implications.

IRF-2 inhibits cancer proliferation by promoting AMER-1 transcription in human gastric cancer.

BACKGROUND: Interferon regulatory factor 2 (IRF-2) acts as an anti-oncogene in gastric cancer (GC); however, the underlying mechanism remains unknown. METHODS: This study determined the expression of IRF-2 in GC tissues and adjacent non-tumor tissues using immunohistochemistry (IHC) and explored the predictive value of IRF-2 for the prognoses of GC patients. Cell function and xenograft tumor growth experiments in nude mice were performed to test tumor proliferation ability, both in vitro and in vivo. Chromatin immunoprecipitation sequencing (ChIP-Seq) assay was used to verify the direct target of IRF-2. RESULTS: We found that IRF-2 expression was downregulated in GC tissues and was negatively correlated with the prognoses of GC patients. IRF-2 negatively affected GC cell proliferation both in vitro and in vivo. ChIP-Seq assay showed that IRF-2 could directly activate AMER-1 transcription and regulate the Wnt/ß-catenin signaling pathway, which was validated using IHC, in both tissue microarray and xenografted tumor tissues, western blot analysis, and cell function experiments. CONCLUSIONS: Increased expression of IRF-2 can inhibit tumor growth and affect the prognoses of patients by directly regulating AMER-1 transcription in GC and inhibiting the Wnt/ß-catenin signaling pathway.

IRF2 enhances RANKL-induced osteoclast differentiation via regulating NF-κB/NFATc1 signaling.

Interferon regulatory factors (IRFs) play roles in various biological processes including cytokine signaling, cell growth regulation and hematopoietic development. Although it has been reported that several IRFs are involved in bone metabolism, the role of IRF2 in bone cells has not been elucidated. Here, we investigated the involvement of IRF2 in RANKL-induced osteoclast differentiation. IRF2 overexpression in osteoclast precursor cells enhanced osteoclast differentiation by regulating the expression of NFATc1, a master regulator of osteoclastogenesis. Conversely, IRF2 knockdown inhibited osteoclast differentiation and decreased the NFATc1 expression. Moreover, IRF2 increased the translocation of NF-κB subunit p65 to the nucleus in response to RANKL and subsequently induced the expression of NFATc1. IRF2 plays an important role in RANKL-induced osteoclast differentiation by regulating NF-κB/NFATc1 signaling pathway. Taken together, we demonstrated the molecular mechanism of IRF2 in osteoclast differentiation, and provide a molecular basis for potential therapeutic targets for the treatment of bone diseases characterized by excessive bone resorption. [BMB Reports 2021; 54(9): 482-487].

Molecular characterization and immune functional analysis of IRF2 in common carp (Cyprinus carpio L.): different regulatory role in the IFN and NF-κB signalling pathway.

BACKGROUND: Interferon regulatory factor 2 (IRF2) is an important transcription factor, which can regulate the IFN response and plays a role in antiviral innate immunity in teleost. RESULTS: In the present study, the full-length cDNA sequence of IRF2 (CcIRF2) was characterized in common carp (Cyprinus carpio L.), which encoded a protein containing a conserved DNA-binding domain (DBD) and an IRF-associated domain (IAD). Phylogenetic analysis showed that CcIRF2 was most closely related with IRF2 of Ctenopharyngodon idella. CcIRF2 transcripts were detectable in all examined tissues, with higher expression in the gills, spleen and brain. CcIRF2 expression was upregulated in immune-related tissues of common carp upon polyinosinic:polycytidylic acid (poly (I:C)) and Aeromonas hydrophila stimulation and induced by poly (I:C), lipopolysaccharide (LPS), peptidoglycan (PGN) and flagellin in the peripheral blood leucocytes (PBLs) and head kidney leukocytes (HKLs). In addition, overexpression of CcIRF2 decreased the expression of IFN and IFN-stimulated genes (ISGs), and a dual-luciferase reporter assay revealed that CcIRF2 could increase the activation of NF-κB. CONCLUSIONS: These results indicate that CcIRF2 participates in antiviral and antibacterial immune response and negatively regulates the IFN response, which provide a new insight into the regulation of IFN system in common carp, and are helpful for the prevention and control of infectious diseases in carp farming.

Propofol Ameliorates Microglia Activation by Targeting MicroRNA-221/222-IRF2 Axis.

BACKGROUND: Propofol is a widely used intravenous anesthetic drug with potential neuroprotective effect in diverse diseases of neuronal injuries such as traumatic brain injury and ischemic stroke. However, the underlying molecular mechanism remains largely unknown. METHODS: Real-time qPCR, enzyme-linked immunosorbent assay, and Western blotting were used to identify the expression pattern of miR-221/222, inflammatory genes, cytokines, and IRF2. The biological roles and mechanisms of propofol in microglia activation were determined in BV2 cells and primary microglia. Bioinformatic analysis and luciferase reporter assay were used to confirm the regulatory role of miR-221/222 in Irf2 expression. RESULTS: We found that miR-221 and miR-222 were downstream targets of propofol and were consistently upregulated in lipopolysaccharide- (LPS-) primed BV2 cells. Gain- and loss-of-function studies revealed that miR-221 and miR-222 were profoundly implicated in microglia activation. Then, interferon regulatory factor 2 (Irf2) was identified as a direct target gene of miR-221/222. IRF2 protein levels were reduced by miR-221/222 and increased by propofol treatment. Ectopic expression of IRF2 attenuated the proinflammatory roles induced by LPS in BV2 cells. More importantly, the suppressive effects of propofol on LPS-primed activation of BV2 cells or primary mouse microglia involved the inhibition of miR-221/222-IRF2 axis. CONCLUSIONS: Our study highlights the critical function of miR-221/222, which inhibited Irf2 translation, in the anti-inflammatory effects of propofol, and provides a new perspective for the molecular mechanism of propofol-mediated neuroprotective effect.

Grass carp (Ctenopharyngodon idella) interferon regulatory factor 8 down-regulates interferon1 expression via interaction with interferon regulatory factor 2 in vitro.

Interferon regulatory factor 8 (IRF8), also known as interferon consensus sequence-binding protein (ICSBP), is a negative regulatory factor of interferon (IFN) and plays an important role in cell differentiation and innate immunity in mammals. In recent years, some irf8 homologous genes have been cloned and confirmed to take part in innate immune response in fish, but the mechanism still remains unclear. In this paper, a grass carp (Ctenopharyngodon idella) irf8 gene (Ciirf8) was cloned and characterized. The deduced protein (CiIRF8) possesses a highly conserved N-terminal DNA binding domain but a less well-conserved C-terminal IRF association domain (IAD). Ciirf8 was widely expressed in all tested tissues of grass carp and up-regulated following poly(I:C) stimulation. Ciirf8 expression was also up-regulated in CIK cells upon treatment with poly(I:C). To explore the molecular mechanism of how fish IRF8 regulates ifn1 expression, the similarities and differences of grass carp IRF8 and IRF2 were compared and contrasted. Subcellular localization analysis showed that CiIRF8 is located both in the cytoplasm and nucleus; however, CiIRF2 is only located in the nucleus. The nuclear-cytoplasmic translocation of CiIRF8 was observed in CIK cells under stimulation with poly(I:C). The interaction of CiIRF8 and CiIRF2 was further confirmed by a co-immunoprecipitation assay in the nucleus. Dual-luciferase reporter assays showed that the promoter activity of Ciifn1 was significantly inhibited by co-transfection with CiIRF2 and CiIRF8. The transcription inhibition of Ciifn1 was alleviated by competitive binding of CiIRF2 and CiIRF8 to CiIRF1. In conclusion, CiIRF8 down-regulates Ciifn1 expression via interaction with CiIRF2 in cells.

IRF2-mediated upregulation of lncRNA HHAS1 facilitates the osteogenic differentiation of bone marrow-derived mesenchymal stem cells by acting as a competing endogenous RNA.

BACKGROUND: Mesenchymal stem cells (MSCs) are the major source of osteoblasts. Long noncoding RNAs (lncRNAs) are abundantly expressed RNAs that lack protein-coding potential and play an extensive regulatory role in cellular biological activities. However, the regulatory network of lncRNAs in MSC osteogenesis needs further investigation. METHODS: QRT-PCR, western blot, immunofluorescence, and immunohistochemistry assays were used to determine the levels of relevant genes. The osteogenic differentiation capability was evaluated by using Alizarin Red S (ARS) staining, alkaline phosphatase activity assays, hematoxylin & eosin staining or micro-CT. RNA fluorescence in situ hybridization (FISH) and RNAscope were used to detect HHAS1 expression in cells and bone tissue. A microarray assay was performed to identify differentially expressed microRNAs. RNA immunoprecipitation and RNA pull-down were used to explore the interactions between related proteins and nucleic acids. RESULTS: The level of lncRNA HHAS1 increased during bone marrow-derived MSC (BMSC) osteogenesis and was positively related to the levels of osteogenic genes and ARS intensity. HHAS1 was located in both the cytoplasm and the nucleus and was expressed in human bone tissue. HHAS1 facilitated BMSC osteogenic differentiation by downregulating miR-204-5p expression and enhancing the level of RUNX family transcription factor 2 (RUNX2). In addition, interferon regulatory factor 2 (IRF2) was increased during BMSC osteogenic differentiation and interacted with the promoter of HHAS1, which resulted in the transcriptional activation of HHAS1. Furthermore, IRF2 and HHAS1 helped improve bone defect repair in vivo. CONCLUSIONS: Our study identified a novel lncRNA, HHAS1, that facilitates BMSC osteogenic differentiation and proposed a role for the IRF2/HHAS1/miR-204-5p/RUNX2 axis in BMSC osteogenesis regulation. These findings help elucidate the regulatory network of BMSC osteogenesis and provide potential targets for clinical application.

LncRNA GAS5 modulates the progression of non-small cell lung cancer through repressing miR-221-3p and up-regulating IRF2.

BACKGROUND: Long non-coding RNA growth arrest specific 5 (GAS5) is a regulator in non-small cell lung cancer (NSCLC) progression. Nonetheless, the mechanism by which GAS5 exerts its biological function in NSCLC cells remains unclear. METHODS: GAS5, miR-221-3p relative expression levels in NSCLC tissues and cells were examined by qPCR. After gain-of-function and loss-of-function models were established, the viability of H1299 and A549 cells were examined by CCK-8 and EdU assays. Cell migration and invasion were examined by the Transwell experiment. The binding sequence of GAS5 for miR-221-3p was confirmed by the dual-luciferase reporter gene experiment. The regulatory function of GAS5 and miR-221-3p on IRF2 was investigated by Western blot. RESULTS: GAS5 expression was down-modulated in NSCLC tissues and cell lines. GAS5 overexpression restrained the proliferation, migration and invasion of NSCLC cells, while miR-221-3p, which was targeted and negatively modulated by GAS5, worked oppositely. Restoration of miR-221-3p markedly reversed the effects of GAS5 on NSCLC cells. Additionally, GAS5 increased IRF2 expression in NSCLC cells by repressing miR-221-3p. CONCLUSIONS: GAS5 blocks the progression of NSCLC partly via increasing IRF2 expression level via repressing miR-221-3p.

Circular RNA hsa_circ_0000658 inhibits osteosarcoma cell proliferation and migration via the miR-1227/IRF2 axis.

Osteosarcoma (OS) is the most frequently occurring bone cancer. Circular RNAs (circRNAs) have been shown to exert pivotal impact in modulation of gene expression, but their roles in OS are still not fully understood. In this study, we analysed the role of circ-0000658 in OS. Thereafter, molecular techniques such as Western blot, qRT-PCR, RNA-binding protein immunoprecipitation and Dual-Luciferase reporter assays were implemented to investigate the role of circ-0000658/miR-1227/interferon regulatory factor-2 (IRF2) axis in OS. Eventually, the impact of circ-0000658 on tumour growth and metastasis was observed in a xenograft mouse model. The results of this study revealed that circ-0000658 exhibits low levels in OS tissues and cell lines. Moreover, circ-0000658 repression promoted cell cycle, proliferation, invasion and migration but inhibited the apoptosis of OS cells. Researches have previously shown that circ-0000658 contains a binding site for miR-1227 and thus can abundantly sponge miR-1227 to up-regulate the expression of its target gene IRF2. Moreover, both inhibition of miR-1227 and overexpression of IRF2 reversed cell proliferation and invasion, which was triggered by circ-0000658 repression. Conclusively, circ-0000658 modulates biological function of OS cells through the miR-1227/IRF2 axis. Therefore, circ-0000658 might act as a possible novel therapeutic target for the treatment of OS.

Identification of Interleukin1ß as an Amplifier of Interferon alpha-induced Antiviral Responses.

The induction of an interferon-mediated response is the first line of defense against pathogens such as viruses. Yet, the dynamics and extent of interferon alpha (IFNα)-induced antiviral genes vary remarkably and comprise three expression clusters: early, intermediate and late. By mathematical modeling based on time-resolved quantitative data, we identified mRNA stability as well as a negative regulatory loop as key mechanisms endogenously controlling the expression dynamics of IFNα-induced antiviral genes in hepatocytes. Guided by the mathematical model, we uncovered that this regulatory loop is mediated by the transcription factor IRF2 and showed that knock-down of IRF2 results in enhanced expression of early, intermediate and late IFNα-induced antiviral genes. Co-stimulation experiments with different pro-inflammatory cytokines revealed that this amplified expression dynamics of the early, intermediate and late IFNα-induced antiviral genes can also be achieved by co-application of IFNα and interleukin1 beta (IL1ß). Consistently, we found that IL1ß enhances IFNα-mediated repression of viral replication. Conversely, we observed that in IL1ß receptor knock-out mice replication of viruses sensitive to IFNα is increased. Thus, IL1ß is capable to potentiate IFNα-induced antiviral responses and could be exploited to improve antiviral therapies.

Development of an IFNγ response-related signature for predicting the survival of cutaneous melanoma.

BACKGROUND: The tumor microenvironment (TME) plays a critical role in tumorigenesis, development, and therapeutic efficacy. Major advances have been achieved in the treatment of various cancers through immunotherapy. Nevertheless, only a minority of patients have positive responses to immunotherapy, which is partly due to conditions of the immunosuppressive microenvironment. Therefore, it is essential to identify prognostic biomarkers that reflect heterogeneous landscapes of the TME. METHODS AND MATERIALS: Based upon the ESTIMATE algorithm, we evaluated the infiltrating levels of immune and stromal components derived from patients afflicted by various types of cancer from The Cancer Genome Atlas database (TCGA). According to respective patient immune and stromal scores, we categorized cases into high- and low-scoring subgroups for each cancer type to explore associations between TME and patient prognosis. Gene Set Enrichment Analyses (GSEA) were conducted and genes enriched in IFNγ response signaling pathway were selected to facilitate establishment of a risk model for predicting overall survival (OS). Furthermore, we investigated the associations between the prognostic signature and tumor immune infiltration landscape by using CIBERSORT algorithm and TIMER database. RESULTS: Among the cancers assessed, the immune scores for skin cutaneous melanoma (SKCM) were the most significantly correlated with patients' survival time (P < .0001). We identified and validated a five-IFNγ response-related gene signature (UBE2L6, PARP14, IFIH1, IRF2, and GBP4), which was closely correlated with the prognosis for SKCM afflicted patients. Multivariate Cox regression analysis indicated that this risk model was an independent prognostic factor for SKCM. Tumor-infiltrating lymphocytes and specific immune checkpoint molecules had notably differential levels of expression in high- compared to low-risk samples. CONCLUSION: In this study, we established a novel five-IFNγ response-related gene signature that provided a better and increasingly comprehensive understanding of tumor immune landscape, and which demonstrated good performance in predicting outcomes for patients afflicted by SKCM.

IRF2 maintains the stemness of colonic stem cells by limiting physiological stress from interferon.

The physiological stresses that diminish tissue stem-cell characteristics remain largely unknown. We previously reported that type I interferon (IFN), which is essential for host antiviral responses, is a physiological stressor for hematopoietic stem cells (HSCs) and small intestinal stem cells (ISCs) and that interferon regulatory factor-2 (IRF2), which attenuates IFN signaling, maintains their stemness. Here, using a dextran sodium sulfate (DSS)-induced colitis model, we explore the role of IRF2 in maintaining colonic epithelial stem cells (CoSCs). In mice with a conditional Irf2 deletion in the intestinal epithelium (hereafter Irf2ΔIEC mice), both the number and the organoid-forming potential of CoSCs were markedly reduced. Consistent with this finding, the ability of Irf2ΔIEC mice to regenerate colon epithelium after inducing colitis was severely impaired, independently of microbial dysbiosis. Mechanistically, CoSCs differentiated prematurely into transit-amplifying (TA) cells in Irf2ΔIEC mice, which might explain their low CoSC counts. A similar phenotype was induced in wild-type mice by repeated injections of low doses of poly(I:C), which induces type I IFN. Collectively, we demonstrated that chronic IFN signaling physiologically stresses CoSCs. This study provides new insight into the development of colitis and molecular mechanisms that maintain functional CoSCs throughout life.

Disentangling molecular mechanisms regulating sensitization of interferon alpha signal transduction.

Tightly interlinked feedback regulators control the dynamics of intracellular responses elicited by the activation of signal transduction pathways. Interferon alpha (IFNα) orchestrates antiviral responses in hepatocytes, yet mechanisms that define pathway sensitization in response to prestimulation with different IFNα doses remained unresolved. We establish, based on quantitative measurements obtained for the hepatoma cell line Huh7.5, an ordinary differential equation model for IFNα signal transduction that comprises the feedback regulators STAT1, STAT2, IRF9, USP18, SOCS1, SOCS3, and IRF2. The model-based analysis shows that, mediated by the signaling proteins STAT2 and IRF9, prestimulation with a low IFNα dose hypersensitizes the pathway. In contrast, prestimulation with a high dose of IFNα leads to a dose-dependent desensitization, mediated by the negative regulators USP18 and SOCS1 that act at the receptor. The analysis of basal protein abundance in primary human hepatocytes reveals high heterogeneity in patient-specific amounts of STAT1, STAT2, IRF9, and USP18. The mathematical modeling approach shows that the basal amount of USP18 determines patient-specific pathway desensitization, while the abundance of STAT2 predicts the patient-specific IFNα signal response.

ELF1 activated long non-coding RNA CASC2 inhibits cisplatin resistance of non-small cell lung cancer via the miR-18a/IRF-2 signaling pathway.

OBJECTIVE: Chemoresistance is the leading cause of recurrence in non-small cell lung cancer (NSCLC). The long non-coding RNA (lncRNA) cancer susceptibility candidate 2 (CASC2) inhibits the tumorigenesis of various cancers. However, the regulatory function of CASC2 on the chemoresistance of NSCLC remains unclear. PATIENTS AND METHODS: The levels of CASC2 and miR-18a in cisplatin (DDP)-resistant NSCLC tissues and cell lines were evaluated by quantitative Polymerase Chain Reaction (qPCR). The role of low CASC2 levels on overall survival in patients with NSCLC was tested using the log-rank test. The Chi-squared test was used to assess the relation between CASC2 expression and clinicopathological features of NSCLC patients. Cell Counting Kit-8 (CCK-8) assays tested the cell proliferation of cisplatin-resistant NSCLC cells (H226/DDP and A549/DDP). The underlying regulatory mechanism between CASC2 and miR-18a or miR-18a and interferon regulatory factor 2 (IRF-2) was predicted by bioinformatics and verified by a Dual-Luciferase reporter assay, RNA transfection, qPCR, and Western blotting. Chromatin immunoprecipitation (ChIP) assay was done to exam the relation between E74 like factor 1 (ELF1) and CASC2 gene. Mice xenografts were applied to exam the function of CASC2 on chemosensitivity of cisplatin of NSCLC cells in vivo. RESULTS: Low CASC2 expression is more likely to present in patients with advanced TNM stage (IV), cisplatin-resistance, and poor overall survival. The expression of CASC2 sharply decreased in cisplatin-resistant NSCLC tissues and cell lines (H226/DDP and A549/DDP). CASC2 overexpression strongly inhibited proliferation, migration, and invasion of cisplatin-resistant NSCLC cells (H226/DDP and A549/DDP) in vitro and inhibited tumor growth in vivo. Besides, CASC2 repressed miR-18a function by binding to the complementary sites of miR-18a as competing endogenous RNAs (ceRNAs). MiR-18a released by the declining expression of CASC2 reduced the protein concentration of IRF-2 in NSCLC cells. Furthermore, the transcription factor ELF1 was found to be promotor of CASC2 and increased its levels in cisplatin-resistant NSCLC cells. CONCLUSIONS: IRF-2 expression mediated by the ELF1/CASC2/miR-18a axis is markedly associated with the proliferation, migration, and invasion of cisplatin-resistant NSCLC, resulting in inferior survival. These findings suggest that this regulatory axis may serve as a novel therapeutic target in NSCLC.