Interferon regulatory factors: A key to tumour immunity

Interference without interferon: interferon-independent induction of interferon-stimulated genes and its role in cellular innate immunity

Interferons (IFNs) are multifaceted proteins that play pivotal roles in orchestrating robust antiviral immune responses and modulating the intricate landscape of host immunity. The major signaling pathway activated by IFNs is the JAK/STAT (Janus kinase/signal transducer and activator of transcription) pathway, which leads to the transcription of a battery of genes, collectively known as IFN-stimulated genes (ISGs). While the well-established role of IFNs in coordinating the innate immune response against viral infections is widely acknowledged, recent years have provided a more distinct comprehension of the functional significance attributed to non-canonical, IFN-independent induction of ISGs. In this review, we summarize the non-conventional signaling pathways of ISG induction. These alternative pathways offer new avenues for developing antiviral strategies or immunomodulation in various diseases.

Crystal Structures of DNA-bound Fish IRF10 and IRF11 Reveal the Determinants of IFN Regulation

IFN regulatory factors (IRFs) are transcription factors that mediate homeostatic mechanisms of host defense against pathogens. In addition to IRF1-9, which are conserved across vertebrates, teleost fishes have two other IRFs, IRF10 and IRF11. In zebrafish (Danio rerio), IRF10 represses the expression of IFNφ1 and IFNφ3, whereas IRF11 exerts the opposite effect. In this study, we found IRF10 could significantly inhibit the expression of IFNφ1 and IFNφ3 induced by IFN11 to synergistically regulate type I IFN expression. To clarify the synergistically regulatory mechanism of IRF10 and IRF11 in type I IFN expression, we determined and analyzed the crystal structures of the DNA-binding domains (DBDs) of zebrafish IRF10 and IRF11 bound to DNA, as well as IRF11 DBD in apo form. The interactions of IRF10-DBD and IRF11-DBD with DNA backbone were elaborated in detail. Further analysis showed that IRF10 and IRF11 have the same binding patterns and comparable affinities with the IFN-sensitive response elements of IFNφ1 and IFNφ3 promoters. Therefore, IRF10 could function as a controlling factor for IRF11 by competitive binding of the IFN-sensitive response elements to coregulate the host IFN response. Accordingly, similar to IRF1 and IRF2 in mammals, IRF10 and IRF11 act as another pair of negative and positive regulators to balance the antiviral responses in fish.

Type I Interferon Activates PD-1 Expression through Activation of the STAT1-IRF2 Pathway in Myeloid Cells

PD-1 (Programmed cell death protein 1) regulates the metabolic reprogramming of myeloid-derived suppressor cells and myeloid cell differentiation, as well as the type I interferon (IFN-I) signaling pathway in myeloid cells in the tumor microenvironment. PD-1, therefore, is a key inhibitory receptor in myeloid cells. However, the regulation of PD-1 expression in myeloid cells is unknown. We report that the expression level of PDCD1, the gene that encodes the PD-1 protein, is positively correlated with the levels of IFNB1 and IFNAR1 in myeloid cells in human colorectal cancer. Treatment of mouse myeloid cell lines with recombinant IFNβ protein elevated PD-1 expression in myeloid cells in vitro. Knocking out IFNAR1, the gene that encodes the IFN-I-specific receptor, diminished the inductive effect of IFNβ on PD-1 expression in myeloid cells in vitro. Treatment of tumor-bearing mice with a lipid nanoparticle-encapsulated IFNβ-encoding plasmid (IFNBCOL01) increased IFNβ expression, resulting in elevated PD-1 expression in tumor-infiltrating myeloid cells. At the molecular level, we determined that IFNβ activates STAT1 (signal transducer and activator of transcription 1) and IRFs (interferon regulatory factors) in myeloid cells. Analysis of the cd279 promoter identified IRF2-binding consensus sequence elements. ChIP (chromatin immunoprecipitation) analysis determined that the pSTAT1 directly binds to the irf2 promoter and that IRF2 directly binds to the cd279 promoter in myeloid cells in vitro and in vivo. In colon cancer patients, the expression levels of STAT1, IRF2 and PDCD1 are positively correlated in tumor-infiltrating myeloid cells. Our findings determine that IFNβ activates PD-1 expression at least in part by an autocrine mechanism via the stimulation of the pSTAT1-IRF2 axis in myeloid cells.

The Role of Interferon Regulatory Factors in Liver Diseases

The interferon regulatory factors (IRFs) family comprises 11 members that are involved in various biological processes such as antiviral defense, cell proliferation regulation, differentiation, and apoptosis. Recent studies have highlighted the roles of IRF1-9 in a range of liver diseases, including hepatic ischemia-reperfusion injury (IRI), alcohol-induced liver injury, Con A-induced liver injury, nonalcoholic fatty liver disease (NAFLD), cirrhosis, and hepatocellular carcinoma (HCC). IRF1 is involved in the progression of hepatic IRI through signaling pathways such as PIAS1/NFATc1/HDAC1/IRF1/p38 MAPK and IRF1/JNK. The regulation of downstream IL-12, IL-15, p21, p38, HMGB1, JNK, Beclin1, β-catenin, caspase 3, caspase 8, IFN-γ, IFN-β and other genes are involved in the progression of hepatic IRI, and in the development of HCC through the regulation of PD-L1, IL-6, IL-8, CXCL1, CXCL10, and CXCR3. In addition, IRF3-PPP2R1B and IRF4-FSTL1-DIP2A/CD14 pathways are involved in the development of NAFLD. Other members of the IRF family also play moderately important functions in different liver diseases. Therefore, given the significance of IRFs in liver diseases and the lack of a comprehensive compilation of their molecular mechanisms in different liver diseases, this review is dedicated to exploring the molecular mechanisms of IRFs in various liver diseases.

Expression of interferon regulatory factor family and its prognostic value in acute myeloid leukemia

Aim: To elucidate the clinicopathological and prognostic values of interferon regulatory factor (IRF) family genes in acute myeloid leukemia (AML). Patients & methods: Differential expression analysis and survival analysis from several reliable databases were conducted and further validated using patients with AML. Results: The expression level of IRF1/2/4/5/7/8/9 in patients with AML was upregulated, while IRF3/6 expression was downregulated. High IRF1/7/9 expression indicated a worse overall survival rate. Conclusion: Overexpression of IRF1/7/9 may be associated with poor survival in patients with AML, suggesting that the IRF family may be a promising therapeutic target.

Targeting cGAS/STING signaling-mediated myeloid immune cell dysfunction in TIME

Myeloid immune cells (MICs) are potent innate immune cells serving as first responders to invading pathogens and internal changes to cellular homeostasis. Cancer is a stage of altered cellular homeostasis that can originate in response to different pathogens, chemical carcinogens, and internal genetic/epigenetic changes. MICs express several pattern recognition receptors (PRRs) on their membranes, cytosol, and organelles, recognizing systemic, tissue, and organ-specific altered homeostasis. cGAS/STING signaling is a cytosolic PRR system for identifying cytosolic double-stranded DNA (dsDNA) in a sequence-independent but size-dependent manner. The longer the cytosolic dsDNA size, the stronger the cGAS/STING signaling activation with increased type 1 interferon (IFN) and NF-κB-dependent cytokines and chemokines' generation. The present article discusses tumor-supportive changes occurring in the tumor microenvironment (TME) or tumor immune microenvironment (TIME) MICs, specifically emphasizing cGAS/STING signaling-dependent alteration. The article further discusses utilizing MIC-specific cGAS/STING signaling modulation as critical tumor immunotherapy to alter TIME.

Construction of an interferon regulatory factors-related risk model for predicting prognosis, immune microenvironment and immunotherapy in clear cell renal cell carcinoma

Background

Interferon regulatory factors (IRFs) played complex and essential roles in progression, prognosis, and immune microenvironment in clear cell renal cell carcinoma (ccRCC). The purpose of this study was to construct a novel IRFs-related risk model to predict prognosis, tumor microenvironment (TME) and immunotherapy response in ccRCC.

Methods

Multi-omics analysis of IRFs in ccRCC was performed based on bulk RNA sequencing and single cell RNA sequencing data. According to the expression profiles of IRFs, the ccRCC samples were clustered by non-negative matrix factorization (NMF) algorithm. Then, least absolute shrinkage and selection operator (LASSO) and Cox regression analyses were applied to construct a risk model to predict prognosis, immune cells infiltration, immunotherapy response and targeted drug sensitivity in ccRCC. Furthermore, a nomogram comprising the risk model and clinical characteristics was established.

Results

Two molecular subtypes with different prognosis, clinical characteristics and infiltration levels of immune cells were identified in ccRCC. The IRFs-related risk model was developed as an independent prognostic indicator in the TCGA-KIRC cohort and validated in the E-MTAB-1980 cohort. The overall survival of patients in the low-risk group was better than that in the high-risk group. The risk model was superior to clinical characteristics and the ClearCode34 model in predicting the prognosis. In addition, a nomogram was developed to improve the clinical utility of the risk model. Moreover, the high-risk group had higher infiltration levels of CD8⁺ T cell, macrophages, T follicular helper cells and T helper (Th1) cells and activity score of type I IFN response but lower infiltration levels of mast cells and activity score of type II IFN response. Cancer immunity cycle showed that the immune activity score of most steps was remarkably higher in the high-risk group. TIDE scores indicated that patients in the low-risk group were more likely responsive to immunotherapy. Patients in different risk groups showed diverse drug sensitivity to axitinib, sorafenib, gefitinib, erlotinib, dasatinib and rapamycin.

Conclusions

In brief, a robust and effective risk model was developed to predict prognosis, TME characteristics and responses to immunotherapy and targeted drugs in ccRCC, which might provide new insights into personalized and precise therapeutic strategies.

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.

Health risks of phthalates: A review of immunotoxicity

Phthalates (PAEs) are known environmental endocrine disruptors that have been widely detected in several environments, and many studies have reported the immunotoxic effects of these compounds. Here, we reviewed relevant published studies, summarized the occurrence and major metabolic pathways of six typical PAEs (DMP, DEP, DBP, BBP, DEHP, and DOP) in water, soil, and the atmosphere, degradation and metabolic pathways under aerobic and anaerobic conditions, and explored the molecular mechanisms of the toxic effects of eleven PAEs (DEHP, DPP, DPrP, DHP, DEP, DBP, MBP, MBzP, BBP, DiNP, and DMP) on the immune system of different organisms at the gene, protein, and cellular levels. A comprehensive understanding of the mechanisms by which PAEs affect immune system function through regulation of immune gene expression and enzymes, increased ROS, immune signaling pathways, specific and non-specific immunosuppression, and interference with the complement system. By summarizing the effects of these compounds on typical model organisms, this review provides insights into the mechanisms by which PAEs affect the immune system, thus supplementing human immune experiments. Finally, we discuss the future direction of PAEs immunotoxicity research, thus providing a framework for the analysis of other environmental pollutants, as well as a basis for PAEs management and safe use.

The roles of glycolysis in osteosarcoma

Metabolic reprogramming is of great significance in the progression of various cancers and is critical for cancer progression, diagnosis, and treatment. Cellular metabolic pathways mainly include glycolysis, fat metabolism, glutamine decomposition, and oxidative phosphorylation. In cancer cells, reprogramming metabolic pathways is used to meet the massive energy requirement for tumorigenesis and development. Metabolisms are also altered in malignant osteosarcoma (OS) cells. Among reprogrammed metabolisms, alterations in aerobic glycolysis are key to the massive biosynthesis and energy demands of OS cells to sustain their growth and metastasis. Numerous studies have demonstrated that compared to normal cells, glycolysis in OS cells under aerobic conditions is substantially enhanced to promote malignant behaviors such as proliferation, invasion, metastasis, and drug resistance of OS. Glycolysis in OS is closely related to various oncogenes and tumor suppressor genes, and numerous signaling pathways have been reported to be involved in the regulation of glycolysis. In recent years, a vast number of inhibitors and natural products have been discovered to inhibit OS progression by targeting glycolysis-related proteins. These potential inhibitors and natural products may be ideal candidates for the treatment of osteosarcoma following hundreds of preclinical and clinical trials. In this article, we explore key pathways, glycolysis enzymes, non-coding RNAs, inhibitors, and natural products regulating aerobic glycolysis in OS cells to gain a deeper understanding of the relationship between glycolysis and the progression of OS and discover novel therapeutic approaches targeting glycolytic metabolism in OS.

IRF7 inhibits the Warburg effect via transcriptional suppression of PKM2 in osteosarcoma

Osteosarcoma (OS) is a malignant bone tumor among adolescents and young adults. IRF7 belongs to the transcription factor family of interferon regulatory factors (IRFs) and has previously been described to function as a tumor suppressor in multiple cancer types. However, the biological functions and cellular mechanism of IRF7 in OS remain elusive. In this study, by quantitative real-time PCR (qRT-PCR) and western blotting, we found that IRF7 was downregulated in OS, and the higher expression of IRF7 was correlated with a better survival prognosis. Moreover, loss-of-function and gain-of-function studies have proved the critical functions of IRF7 in suppressing aerobic glycolysis of osteosarcoma cells as evidenced by glucose uptake, lactate production, extracellular acidification rate, and oxygen consumption rate. Mechanistically, IRF7 inhibited the expression of key glycolytic gene PKM2 via direct transcriptional regulation. Moreover, the in vitro and in vivo tumor-suppressive roles of IRF7 were uncovered in OS and these effects were largely glycolysis-dependent. Therefore, our study unveils a previous unprecedented role of IRF7 in glucose metabolism reprogram and suggests that IRF7 might serve as a potential therapeutic target for patients with OS.

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/β-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/β-catenin signaling pathway.

IRF2 inhibits ZIKV replication by promoting FAM111A expression to enhance the host restriction effect of RFC3

BACKGROUND

Although interferon regulatory factor 2 (IRF2) was reported to stimulate virus replication by suppressing the type I interferon signaling pathway, because cell cycle arrest was found to promote viral replication, IRF2-regulated replication fork factor (FAM111A and RFC3) might be able to affect ZIKV replication. In this study, we aimed to investigate the function of IRF2, FAM111A and RFC3 to ZIKV replication and underlying mechanism.

METHODS

siIRF2, siFAM111A, siRFC3 and pIRF2 in ZIKV-infected A549, 2FTGH and U5A cells were used to explore the mechanism of IRF2 to inhibit ZIKV replication. In addition, their expression was analyzed by RT-qPCR and western blots, respectively.

RESULTS

In this study, we found IRF2 expression was increased in ZIKV-infected A549 cells and IRF2 inhibited ZIKV replication independent of type I IFN signaling pathway. IRF2 could activate FAM111A expression and then enhanced the host restriction effect of RFC3 to inhibit replication of ZIKV.

CONCLUSIONS

We speculated the type I interferon signaling pathway might not play a leading role in regulating ZIKV replication in IRF2-silenced cells. We found IRF2 was able to upregulate FAM111A expression and thus enhance the host restriction effect of RFC3 on ZIKV.

Interferon regulatory factor family influences tumor immunity and prognosis of patients with colorectal cancer

Background

Since interferon regulatory factor (IRF) family functions in immune response to viral infection, its role in colorectal cancer (CRC) has not been inspected before. This study tries to investigate members of IRF family using bioinformatics approaches in aspect of differential expressions, biological function, tumor immune infiltration and clinical prognostic value for patients with CRC.

Methods

Transcriptome profiles data, somatic mutations and clinical information of CRC were obtained from COAD/READ dataset of The Cancer Genome Atlas (TCGA) as a training set. Gene expression data (GSE17536 and GSE39582) were downloaded from the Gene Expression Omnibus as a validating set. A random forest algorithm was used to score the risk for every case. Analyzing gene and function enrichment, constructing protein–protein interaction and noncoding RNA network, identifying hub-gene, characterizing tumor immune infiltration, evaluating differences in tumor mutational burden (TMB) and sensitivity to chemotherapeutics or immunotherapy were performed by a series of online tools and R packages. Immunohistochemical (IHC) examinations were carried out validation in tissue samples.

Results

Principal-component analysis (PCA) suggested that the transcript expression levels of nine members of IRF family differed between normal colorectum and CRC. The risk score constructed by IRF family not only acted as an independent factor for predicting survival in CRC patients with different biological processes, signaling pathways and TMB, but also indicated different immunotherapy response with diverse immune and stromal cells infiltration. IRF3 and IRF7 were upregulated in CRC and suggested a shorter survival time in patients with CRC. Differentially expressed members of IRF family exhibited varying degrees of immune cell infiltration. IHC analysis showed a positive association between IRF3 and IRF7 expression and tumor-infiltrating immune cells, including CD4⁺ T cell and CD68⁺ macrophages.

Conclusions

On account of differential expression, IRF family members can help to predict both response to immunotherapy and clinical prognosis of patients with CRC. Our bioinformatic investigation not only gives a preliminary picture of the genetic features as well as tumor microenvironment, but it may provide a clue for further experimental exploration and verification on IRF family members in CRC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03054-3.

Clinically used JAK inhibitor blunts dsRNA-induced inflammation and calcification in aortic valve interstitial cells

Calcific aortic valve disease (CAVD) is the most prevalent valvulopathy worldwide. Growing evidence supports a role for viral and cell-derived double-stranded (ds)-RNA in cardiovascular pathophysiology. Poly(I:C), a dsRNA surrogate, has been shown to induce inflammation, type I interferon (IFN) responses, and osteogenesis through Toll-like receptor 3 in aortic valve interstitial cells (VIC). Here, we aimed to determine whether IFN signaling via Janus kinase (JAK)/Signal transducers and activators of transcription (STAT) mediates dsRNA-induced responses in primary human VIC. Western blot, ELISA, qPCR, calcification, flow cytometry, and enzymatic assays were performed to evaluate the mechanisms of dsRNA-induced inflammation and calcification. Poly(I:C) triggered a type I IFN response characterized by IFN-regulatory factors gene upregulation, IFN-β secretion, and STAT1 activation. Additionally, Poly(I:C) promoted VIC inflammation via NF-κB and subsequent adhesion molecule expression, and cytokine secretion. Pretreatment with ruxolitinib, a clinically used JAK inhibitor, abrogated these responses. Moreover, Poly(I:C) promoted a pro-osteogenic phenotype and increased VIC calcification to a higher extent in cells from males. Inhibition of JAK with ruxolitinib or a type I IFN receptor blocking antibody blunted Poly(I:C)-induced calcification. Mechanistically, Poly(I:C) promoted VIC apoptosis in calcification medium, which was inhibited by ruxolitinib. Moreover, Poly(I:C) co-operated with IFN-γ to increase VIC calcification by synergistically activating extracellular signal-regulated kinases and hypoxia-inducible factor-1α pathways. In conclusion, JAK/STAT signaling mediates dsRNA-triggered inflammation, apoptosis, and calcification and may contribute to a positive autocrine loop in human VIC in the presence of IFN-γ. Blockade of dsRNA responses with JAK inhibitors may be a promising therapeutic avenue for CAVD.

Interferon regulatory factor transcript levels correlate with clinical outcomes in human glioma

Members of the interferon regulatory factor (IRF) gene family are crucial regulators of type I interferon signaling, which may play a role in the resistance of glioma to immune checkpoint blockade. However, the expression profiles, potential functions, and clinical significance of IRF family members remain largely unknown. Here, we examined IRF transcript levels and clinicopathological data from glioma patients using several bioinformatic databases, including ONCOMINE, GEPIA, TCGA, and cBioPortal. We found that IRF1, IRF2, IRF5, IRF8 and IRF9 were significantly upregulated in glioma compared to normal brain tissue. Higher IRF1, IRF2, IRF3, IRF4, IRF5, IRF7, IRF8 and IRF9 mRNA levels correlated with more advanced tumor grades and poorer outcomes. Moreover, although IRFs mutation rates were low (ranging from 0.5% to 2.3%) in glioma patients, genetic alterations in IRFs were associated with more favorable patient survival. Functional analysis showed that IRFs participated in glioma pathology mainly through multiple inflammation- and immunity-related pathways. Additionally, correlations were identified between IRFs and infiltration of immune cells within glioma tissues. Collectively, these results indicate that IRF family members, including IRF1, IRF2, IRF5, IRF8 and IRF9, may serve as prognostic biomarkers and indicators of immune status in glioma patients.

Negative Regulation of SIRT1 by IRF9 Involved in Hyperlipidemia Acute Pancreatitis Associated with Kidney Injury

BACKGROUND

Interferon regulatory factor 9 (IRF9) acts as a negative regulator of sirtuin-1 (SIRT1) to participate in many diseases. However, the role of SIRT1 and IRF9 in hyperlipidemia acute pancreatitis associated with kidney injury is unclear.

AIMS

To explore the function of SIRT1 and IRF9 in hyperlipidemia acute pancreatitis associated with kidney injury and provide theoretical guidance for disease diagnosis and treatment.

METHODS

Model rats were established by intraperitoneal injection of 20% L-arginine. Apoptosis of kidney tissue was determined by TUNEL staining. Expressions of IRF9, SIRT1, p53, and acetylated p53 were detected by qRT-PCR and Western blot. Dual-Luciferase Reporter Assay was carried out to validate the regulation of IRF9 on SIRT1.

RESULTS

Pancreatic and renal injury was more serious, and apoptosis of kidney epithelial cells increased in acute pancreatitis (AP) and hyperlipidemia acute pancreatitis (HLAP) group. IRF9, p53, and acetylated p53 were up-regulated, and SIRT1 was down-regulated in AP and HLAP group (p < 0.05). Down-regulation of SIRT1 was negatively correlated with up-regulation of IRF9 in AP and HLAP group (p < 0.05). Pancreatic and renal injury and kidney epithelial cells apoptosis in HLAP group were more obvious than AP group (p < 0.05). The up-regulation of IRF9 and down-regulation of SIRT1 in HLAP group were more than AP group (p < 0.05). The promoter activity of SIRT1 was repressed by IRF9.

CONCLUSION

In pancreatitis associated with kidney injury, IRF9 was a negative regulator of SIRT1, down-regulated the expression of SIRT1, increased acetylated p53, and promoted renal cell apoptosis. Hyperlipidemia further aggravated pancreatic and renal injury and renal cell apoptosis.

Interferon regulatory factor 6 correlates with the progression of non-small cell lung cancer and can be regulated by miR-320

OBJECTIVES

The expression of interferon regulatory factor 6 (IRF6) has been reported in several cancer types, but its roles underlying the progression of lung cancer have not been detailedly investigated.

METHODS

The pairs of lung cancer tissues and para-carcinoma tissues and The Cancer Genome Atlas database were collected to detect IRF6 expression. Cell counting kit-8, transwell and terminal-deoxynucleoitidyl transferase-mediated nick end labelling assays were used to evaluate cell proliferation, migration and apoptosis.

KEY FINDINGS

A significant up-regulation of IRF6 in both lung adenocarcinoma and lung squamous cell carcinoma tissues compared with normal non-tumor tissues. Subsequently, Immunostaining also revealed that canceration of lung tissues predisposed to evoke IRF6 expression. In vitro experiments revealed the antitumour effects, including growth and migration inhibition, of IRF6 siRNA transfection. Considering miR-320 as an endogenous inhibitor to IRF6, miR-320 mimics transfection led to the inhibition of proliferation and migration of lung cancer cells. However, overexpressed IRF6 neutralized the antineoplastic activities of miR-320 in lung cancer cells.

CONCLUSIONS

The miR-320/IRF6 signalling axis was implicated in pulmonary canceration. miR-320 as an endogenous inhibitor of IRF6 provided a novel therapeutic strategy for the treatment of lung cancer.

M2 macrophages contribute to cell proliferation and migration of breast cancer

Breast cancer is a kind of malignant tumor that severely threatens women's lives and health worldwide. Tumor-associated macrophages (TAMs) have been reported to mediate tumor progression, while the mechanism still needs further identification. In this study, we found that M2 macrophages promoted increased cell proliferation and migration as well as reduced expression of interferon regulatory factor 7 (IRF7) and increased the expression of miR-1587 in breast cancer cells. Overexpression of IRF7 or miR-1587 knockdown reversed M2 macrophage-induced cell proliferation and migration as well as tumor growth in vivo. Mechanistically, miR-1587 targeted the 3'-untranslated region (3'-UTR) of IRF7 mRNA to regulate its protein expression leading to tumor progression. Collectively, this study revealed that the miR-1587/IRF7 axis mediates M2 macrophage-induced breast cancer progression, and this sheds light on further clinical therapy for breast cancer by targeting TAMs as well as the miR-1587/IRF7 axis.

Identification of the Prognostic Value and Clinical Significance of Interferon Regulatory Factors (IRFs) in Colon Adenocarcinoma

BACKGROUND Colon adenocarcinoma (COAD) is one of the most common malignant tumors and has high incidence and mortality rates. The interferon regulatory factor (IRF) family is known as a key transcription factor in the IFN signaling pathway and cellular immunity. This research explored the relationship between the IRF family and COAD through use of bioinformatics technology. MATERIAL AND METHODS Using the UALCAN and GEPIA databases, we analyzed the transcription and prognostic value of IRFs in COAD, and GSCALite was used in cancer genomics analysis. TIMER, LinkedOmics, and Metascape were used to assess the potential function of IRFs in COAD. RESULTS The transcription levels of IRF3 were elevated in COAD tissues, while IRF2/4/6 were downregulated compared with normal patients in subgroup analyses of race, age, weight, sex, nodal metastasis, individual cancer stages, TP53 mutation status, and histological subtypes. IRF3 and IRF7 in COAD were significantly associated with a poor prognosis. Drug sensitivity analysis revealed that the expression level of IRF2/4/8 was negatively associated with drug resistance. A significant correlation was found between the IRF family and immune cell infiltration. Moreover, enrichment analysis revealed that the IRFs were associated with response to tumor necrosis factor, transcription misregulation in cancer, and JAK-STAT signaling pathway. We also identified several kinase and miRNA targets of the IRF family in COAD. CONCLUSIONS We identified IRF3 and IRF7 as prognostic biomarkers in COAD, and the IRF family was associated with immune cell infiltration and gene regulation networks, providing additional evidence showing the significant role of the IRF family in COAD.

A novel function of IRF9 in acute pancreatitis by modulating cell apoptosis, proliferation, migration, and suppressing SIRT1-p53

Acute pancreatitis (AP) is an inflammatory disease caused by the abnormal activation of pancreatic enzymes in the pancreas, with a considerably high morbidity and mortality. However, the etiological factor and pathogenesis of AP are still unclear. This study was aimed to explore the role and mechanism of interferon regulatory factor 9 (IRF9) in the occurrence of AP and to provide experimental and theoretical foundation for AP diagnosis and treatment. AP model in vitro was established by caerulein-induced group. Small interfering RNA (siRNA) was designed and constructed to silence IRF9 gene. After siRNA transfected and caerulein treated successfully, the expression levels of IRF9, SIRT1, and acetylated p53 (Ac-p53) were determined by qRT-PCR and Western blot. The apoptosis, proliferation, and migration of AR42J cells were checked by flow cytometry, MTT, and transwell assay. Dual-luciferase reporter assay was implemented to validate the regulatory effect of IRF9 on SIRT1. Here, our study showed that the expression of IRF9 and Ac-p53 was increased, SIRT1 was decreased, and cell apoptosis, proliferation, and migration of AR42J cells were increased after caerulein induced. IRF9 gene silencing upregulated SIRT1, downregulated Ac-p53, and inhibited cell apoptosis, proliferation, and migration. Dual-Luciferase reporter assay showed that IRF9 could negatively regulate SIRT1. The potential mechanism was that IRF9 could modulate cell apoptosis, proliferation, migration, and bind the promoter of SIRT1 to repress SIRT1-p53. It hinted that IRF9 showed a novel function in AP by modulating cell apoptosis, proliferation, migration, and suppressing SIRT1-p53. IRF9 might be a good potential treatment target for AP.

Functional Analysis of IRF1 Reveals its Role in the Activation of the Type I IFN Pathway in Golden Pompano, Trachinotus ovatus (Linnaeus 1758)

Interferon (IFN) regulatory factor 1 (IRF1), a transcription factor with a novel helix–turn–helix DNA-binding domain, plays a crucial role in innate immunity by regulating the type I IFN signaling pathway. However, the regulatory mechanism through which IRF1 regulates type I IFN in fish is not yet elucidated. In the present study, IRF1 was characterized from golden pompano, Trachinotus ovatus (designated ToIRF1), and its immune function was identified to elucidate the transcriptional regulatory mechanism of ToIFNa3. The full-length complementary DNA (cDNA) of IRF1 is 1763 bp, including a 900-bp open reading frame (ORF) encoding a 299-amino-acid polypeptide. The putative protein sequence has 42.7–71.7% identity to fish IRF1 and possesses a representative conserved domain (a DNA-binding domain (DBD) at the N-terminus). The genomic DNA sequence of ToIRF1 consists of eight exons and seven introns. Moreover, ToIRF1 is constitutively expressed in all examined tissues, with higher levels being observed in immune-relevant tissues (whole blood, gill, and skin). Additionally, Cryptocaryon irritans challenge in vivo increases ToIRF1 expression in the skin as determined by Western blotting (WB); however, protein levels of ToIRF1 in the gill did not change significantly. The subcellular localization indicates that ToIRF1 is localized in the nucleus and cytoplasm with or without polyinosinic/polycytidylic acid (poly (I:C)) induction. Furthermore, overexpression of ToIRF1 or ToIFNa3 shows that ToIRF1 can notably activate ToIFNa3 and interferon signaling molecule expression. Promoter sequence analysis finds that several interferon stimulating response element (ISRE) binding sites are present in the promoter of ToIFNa3. Additionally, truncation, point mutation, and electrophoretic mobile shift (EMSA) assays confirmed that ToIRF1 M5 ISRE binding sites are functionally important for ToIFNa3 transcription. These results may help to illuminate the roles of teleost IRF1 in the transcriptional mechanisms of type I IFN in the immune process.

Taking the lead - how keratinocytes orchestrate skin T cell immunity

The skin comprises a complex coordinated system of epithelial tissue cells and immune cells that ensure adequate immune reactions against trauma, toxins and pathogens, while maintaining tissue homeostasis. Keratinocytes form the outermost barrier of the skin, and sense changes in barrier integrity, intrusion of microbial components and stress molecules. Thus, they act as sentinels that continuously communicate the status of the organ to the cutaneous immune system. Upon damage the keratinocytes initiate a pro-inflammatory signaling cascade that leads to the activation of resident immune cells. Simultaneously, the tissue mediates and supports immune-suppressive functions to contain inflammation locally. After resolution of inflammation, the skin provides a niche for regulatory and effector memory T cells that can quickly respond to reoccurring antigens. In this review we discuss the central role of keratinocyte-derived signals in controlling cutaneous T cell immunity.