IRF1

Gene Summary

Gene:IRF1; interferon regulatory factor 1
Aliases: MAR, IRF-1
Location:5q31.1
Summary:IRF1 encodes interferon regulatory factor 1, a member of the interferon regulatory transcription factor (IRF) family. IRF1 serves as an activator of interferons alpha and beta transcription, and in mouse it has been shown to be required for double-stranded RNA induction of these genes. IRF1 also functions as a transcription activator of genes induced by interferons alpha, beta, and gamma. Further, IRF1 has been shown to play roles in regulating apoptosis and tumor-suppressoion. [provided by RefSeq, Jul 2008]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:interferon regulatory factor 1
Source:NCBIAccessed: 16 March, 2017

Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 16 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Selection, Genetic
  • Neoplastic Cell Transformation
  • Cell Proliferation
  • Young Adult
  • Molecular Sequence Data
  • Phosphoproteins
  • Interferon Regulatory Factor-2
  • Phosphorylation
  • Single Nucleotide Polymorphism
  • Antineoplastic Agents
  • Retinoic Acid
  • RTPCR
  • Th2 Cells
  • Polymerase Chain Reaction
  • Messenger RNA
  • Interferon-alpha
  • Cancer Gene Expression Regulation
  • p53 Protein
  • Gene Expression
  • Tumor Escape
  • Western Blotting
  • Breast Cancer
  • Upstream Stimulatory Factors
  • IRF1
  • Signal Transduction
  • DNA-Binding Proteins
  • Promoter Regions
  • Trans-Activators
  • STAT1 Transcription Factor
  • Stomach Cancer
  • Viral Proteins
  • Apoptosis
  • Base Sequence
  • Interferon-gamma
  • Uvea
  • Transcription Factors
  • Cell Division
  • Chromosome 5
  • Repressor Proteins
  • TNF
  • Gene Expression Regulation
Tag cloud generated 16 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (2)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: IRF1 (cancer-related)

Wang B, Yang H, Shen L, et al.
Rs56288038 (C/G) in 3'UTR of IRF-1 Regulated by MiR-502-5p Promotes Gastric Cancer Development.
Cell Physiol Biochem. 2016; 40(1-2):391-399 [PubMed] Related Publications
BACKGROUND/AIMS: Interferon regulatory factor 1 (IRF-1) has been shown to function as a transcriptional activator or repressor of a variety of target genes. However, its upstream, non-coding RNA-related regulatory capacity remains unknown. In this study, we focus on the miRNA-associated single nucleotide polymorphisms (SNPs) in the 3'untranslated region (UTR) of IRF-1 to further investigate the functional relationship and potential diagnostic value of the SNPs and miRNAs among Chinese gastric cancer (GC) patients.
METHODS: We performed a case-control study with 819 GC patients and 756 cancer-free controls. Genotyping by realtime PCR assay, cell transfection, and the dual luciferase reporter assay were used in our study, and the 5-year overall survival rate and relapse-free survival rate in different groups were investigated.
RESULTS: We found that patients suffering from Helicobacter pylori (Hp) infection were the susceptible population compared to controls. SNP rs56288038 (C/G) in IRF-1 3'UTR was involved in the occurrence of GC by acting as a tumor promoter factor. SNP rs56288038 (C/G) could be up-regulated by miR-502-5p, which caused a down-regulation of IRF-1 in cell lines and decreased apoptosis induced by IFN-γ. Carrying the G genotype was related to significantly low expression of IRF-1 and Hp infection, poor differentiation, big tumor size, invasion depth, as well as the high probability of metastasis, and moreover, the C/G SNP was associated with shorter survival of GC patients with five years of follow-up study.
CONCLUSIONS: our findings have shown that the SNP rs56288038 (C/G) in IRF-1 3'UTR acted as a promotion factor in GC development through enhancing the regulatory role of miR-502-5p in IRF-1 expression.

Xie C, Guo B, Liu C, et al.
[Endogenous IFN-β maintains M1 polarization status and inhibits proliferation and invasion of hepatocellular carcinoma cells].
Xi Bao Yu Fen Zi Mian Yi Xue Za Zhi. 2016; 32(7):865-9 [PubMed] Related Publications
Objective To investigate the effect of endogenous interferon β (IFN-β) on the polarization of M1 macrophages as well as the proliferation and invasion activities of hepatocellular carcinoma cells (HCCs) mediated by M1 macrophages. Methods U937-M1 macrophages derived from human monocytic tumor cells U937 was established and the cell phenotypes were identified by real-time quantitative PCR, ELISA and flow cytometry. After IFN-β gene was knocked down with siRNA or IFN-β was neutralized with IFN-β monoantibody in U937-M1 macrophages, the change of M1/M2 phenotype was again analyzed by the above methods. The expressions of interferon regulatory factor 1 (IRF1) and IRF5 were detected by real-time quantitative PCR and Western blotting. The proliferation and invasion activities of HCCs, which were cultured with conditioned medium (CM) collected from different macrophage groups, were analyzed by CCK-8 assay and Transwell(TM) experiments, respectively. Results U937-M1 macrophages showed higher expressions of interleukin 12p35 (IL-12p35), interleukin 12p40 (IL-12p40), interleukin 12p70 (IL-12p70), interleukin 23p19 (IL-23p19), interleukin 6 (IL-6), tumor necrosis factor α (TNF-α) and CD86 than U937-M0 did. But both U937-M0 macrophages and U937-M1 macrophages showed low expression of CD206. However, compared with the U937-M1 macrophages, the IFN-β-blocked U937-M1 macrophages presented decreased expressions of the above M1 macrophages-associated markers, but increased expressions of M2 macrophages-associated markers IL-10 and CD206, as well as lower expressions of IRF1 and IRF5. The inhibited proliferation/invasion activities of HCCs mediated by U937-M1 macrophages were reversed by IFN-β-blocked U937-M1 macrophages. Conclusion Blocking endogenous IFN-β could inhibit the U937-M1 polarization status and U937-M1 macrophages-mediated anti-tumor activity of HCCs. IFN-β might be involved in modulating the expressions of IRF1 and IRF5 as well as maintaining the M1 polarization status and its function.

Yan Y, Liang Z, Du Q, et al.
MicroRNA-23a downregulates the expression of interferon regulatory factor-1 in hepatocellular carcinoma cells.
Oncol Rep. 2016; 36(2):633-40 [PubMed] Free Access to Full Article Related Publications
Interferon regulatory factor-1 (IRF-1) is a tumor-suppressor gene induced by interferon-γ (IFNγ) and plays an important role in the cell death of hepatocellular carcinoma (HCC). HCC tumors evade death in part by downregulating IRF-1 expression, yet the molecular mechanisms accounting for IRF-1 suppression in HCC have not yet been characterized. Previous studies have shown that microRNA-23a (miR-23a) can suppress apoptosis by targeting IRF-1. Therefore, we hypothesized that miR-23a promotes HCC growth by downregulating IRF-1. For the in vivo studies, 7 cases of resected HCC and adjacent liver samples were analyzed. For the in vitro studies, IRF-1 mRNA and protein were examined in HepG2 and Huh-7 HCC cells after IFNγ stimulation by real-time PCR and western blotting, respectively. To determine the role of miR-23a in regulating IRF-1, HepG2 cells were transfected with an miR-23a mimic or inhibitor, and IRF-1 expression was examined. Binding of miR-23a was assessed by cloning the 528-bp human IRF-1 3'-untranslated region (3'UTR) into luciferase reporter plasmid pMIR-IRF-1-3'UTR. The results showed that IRF-1 mRNA expression was downregulated in the human HCC tumor tissues compared to that in the adjacent background liver tissues. IFNγ-induced IRF-1 protein was less in the HepG2 tumor cells compared to that in the primary human hepatocytes. miR-23a expression was inversely correlated with IRF-1, and addition of the miR-23a inhibitor increased basal IRF-1 mRNA and protein. Likewise, the miR-23a mimic downregulated IFNγ-induced IRF-1 protein expression, while the miR-23a inhibitor increased IRF-1. Furthermore, the miR-23a mimic repressed IRF-1-3'UTR reporter activity, while the miR-23a inhibitor increased the reporter activity. These results demonstrated that IRF-1 expression is downregulated in human HCC tumors compared to that noted in the background liver. miR-23a downregulates the expression of IRF-1 in HCC cells, and the IRF-1 3'UTR has an miR‑23a binding site that binds miR-23a and decreases reporter activity. These findings suggest that the targeting of IRF-1 by miR-23a may be the molecular basis for IRF-1 downregulation in HCC and provide new insight into the regulation of HCC by miRNAs.

Kochupurakkal BS, Wang ZC, Hua T, et al.
RelA-Induced Interferon Response Negatively Regulates Proliferation.
PLoS One. 2015; 10(10):e0140243 [PubMed] Free Access to Full Article Related Publications
Both oncogenic and tumor-suppressor activities are attributed to the Nuclear Factor kappa B (NF-kB) pathway. Moreover, NF-kB may positively or negatively regulate proliferation. The molecular determinants of these opposing roles of NF-kB are unclear. Using primary human mammary epithelial cells (HMEC) as a model, we show that increased RelA levels and consequent increase in basal transcriptional activity of RelA induces IRF1, a target gene. Induced IRF1 upregulates STAT1 and IRF7, and in consort, these factors induce the expression of interferon response genes. Activation of the interferon pathway down-regulates CDK4 and up-regulates p27 resulting in Rb hypo-phosphorylation and cell cycle arrest. Stimulation of HMEC with IFN-γ elicits similar phenotypic and molecular changes suggesting that basal activity of RelA and IFN-γ converge on IRF1 to regulate proliferation. The anti-proliferative RelA-IRF1-CDK4 signaling axis is retained in ER+/HER2- breast tumors analyzed by The Cancer Genome Atlas (TCGA). Using immuno-histochemical analysis of breast tumors, we confirm the negative correlation between RelA levels and proliferation rate in ER+/HER2- breast tumors. These findings attribute an anti-proliferative tumor-suppressor role to basal RelA activity. Inactivation of Rb, down-regulation of RelA or IRF1, or upregulation of CDK4 or IRF2 rescues the RelA-IRF1-CDK4 induced proliferation arrest in HMEC and are points of disruption in aggressive tumors. Activity of the RelA-IRF1-CDK4 axis may explain favorable response to CDK4/6 inhibition observed in patients with ER+ Rb competent tumors.

Care MA, Westhead DR, Tooze RM
Gene expression meta-analysis reveals immune response convergence on the IFNγ-STAT1-IRF1 axis and adaptive immune resistance mechanisms in lymphoma.
Genome Med. 2015; 7:96 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Cancers adapt to immune-surveillance through evasion. Immune responses against carcinoma and melanoma converge on cytotoxic effectors and IFNγ-STAT1-IRF1 signalling. Local IFN-driven immune checkpoint expression can mediate feedback inhibition and adaptive immune resistance. Whether such coupled immune polarization and adaptive resistance is generalisable to lymphoid malignancies is incompletely defined. The host response in diffuse large B-cell lymphoma (DLBCL), the commonest aggressive lymphoid malignancy, provides an empirical model.
METHODS: Using ten publicly available gene expression data sets encompassing 2030 cases we explore the nature of host response in DLBCL. Starting from the "cell of origin" paradigm for DLBCL classification, we use the consistency of differential expression to define polarized patterns of immune response genes in DLBCL, and derive a linear classifier of immune response gene expression. We validate and extend the results in an approach independent of "cell of origin" classification based on gene expression correlations across all data sets.
RESULTS: T-cell and cytotoxic gene expression with polarization along the IFNγ-STAT1-IRF1 axis provides a defining feature of the immune response in DLBCL. This response is associated with improved outcome, particularly in the germinal centre B-cell subsets of DLBCL. Analysis of gene correlations across all data sets, independent of "cell of origin" class, demonstrates a consistent association with a hierarchy of immune-regulatory gene expression that places IDO1, LAG3 and FGL2 ahead of PD1-ligands CD274 and PDCD1LG2.
CONCLUSION: Immune responses in DLBCL converge onto the IFNγ-STAT1-IRF1 axis and link to diverse potential mediators of adaptive immune resistance identifying future therapeutic targets.

Liang J, Piao Y, Henry V, et al.
Interferon-regulatory factor-1 (IRF1) regulates bevacizumab induced autophagy.
Oncotarget. 2015; 6(31):31479-92 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Antiangiogenic therapy is commonly being used for the treatment of glioblastoma. However, the benefits of angiogenesis inhibitors are typically transient and resistance often develops. Determining the mechanism of treatment failure of the VEGF monoclonal antibody bevacizumab for malignant glioma would provide insight into approaches to overcome therapeutic resistance.
EXPERIMENTAL DESIGN: In this study, we evaluated the effects of bevacizumab on the autophagy of glioma cells and determined target genes involving in the regulation of bevacizumab-induced autophagy.
RESULTS: We demonstrated that bevacizumab treatment increased expression of autophagy markers and autophagosome formation in cell culture experiments as well as in in vivo studies. Gene expression profile analysis performed on murine xenograft models of glioblastoma showed increased transcriptional levels of STAT1/IRF1 signaling in bevacizumab resistant tumors compared to control tumors. In vitro experiments showed that bevacizumab treatment increased IRF1 expression in a dose and time dependent manner, which was coincident with bevacizumab-mediated autophagy. Down regulation of IRF1 by shRNA blocked autophagy and increased AIF-dependent apoptosis in bevacizumab-treated glioma cells. Consistently, IRF1 depletion increased the efficacy of anti-VEGF therapy in a glioma xenograft model, which was due to less bevacizumab-promoted autophagy and increased apoptosis in tumors with down-regulated IRF1.
CONCLUSIONS: These data suggest that IRF1 may regulate bevacizumab-induced autophagy, and may be one important mediator of glioblastoma resistant to bevacizumab.

Hayashi T, Horiuchi A, Sano K, et al.
Uterine Leiomyosarcoma Tumorigenesis in Lmp2-deficient Mice: Involvement of Impaired Anti-oncogenic Factor IRF1.
Anticancer Res. 2015; 35(9):4665-79 [PubMed] Related Publications
BACKGROUND/AIM: Uterine leiomyosarcoma (Ut-LMS) is a highly metastatic smooth muscle neoplasm. We have previously reported that low molecular mass protein2 Lmp2-deficient mice spontaneously developed Ut-LMS, which implicated this protein as an anti-oncogenic candidate. We also suggested that LMP2 may negatively regulate Ut-LMS independently of its role in the proteasome. Initially described as a transcription factor able to activate the expression of interferon-gamma (IFN-γ)-responsive genes, interferon regulatory factor-1 (IRF1) has been shown to play roles in the immune response, and tumor suppression. The aim of this study was to elucidate the molecular mechanism of sarcomagenesis of Ut-LMS using human and mouse uterine tissues.
MATERIALS AND METHODS: The expression of the IFN-γ signal molecules, IRF1 and -2, STAT1, and LMP2, -3, -7 and -10 were examined by western blot analysis, electrophoretic mobility shift assay and immunohistochemistry in human and mouse uterine tissues. Physiological significance of IRF1 in sarcomagenesis of Ut-LMS was demonstrated by xenograft studies.
RESULTS: In the present study, several lines of evidence indicated that although treatment with IFN-γ strongly induced the activation of STAT1 as a transcriptional activator, its target molecule, IRF1, was not clearly produced in Lmp2-deficient uterine smooth muscle cells (Ut-SMCs).
CONCLUSION: Defective expression of IRF1 in the IFN-γ-induced signaling molecules may result in the malignant transformation of Ut-SMCs. The modulation of LMP2 may lead to new therapeutic approaches in human Ut-LMS.

Armstrong MJ, Stang MT, Liu Y, et al.
IRF-1 inhibits NF-κB activity, suppresses TRAF2 and cIAP1 and induces breast cancer cell specific growth inhibition.
Cancer Biol Ther. 2015; 16(7):1029-41 [PubMed] Free Access to Full Article Related Publications
Interferon Regulatory Factor (IRF)-1, originally identified as a transcription factor of the human interferon (IFN)-β gene, mediates tumor suppression and may inhibit oncogenesis. We have shown that IRF-1 in human breast cancer cells results in the down-regulation of survivin, tumor cell death, and the inhibition of tumor growth in vivo in xenogeneic mouse models. In this current report, we initiate studies comparing the effect of IRF-1 in human nonmalignant breast cell and breast cancer cell lines. While IRF-1 in breast cancer cells results in growth inhibition and cell death, profound growth inhibition and cell death are not observed in nonmalignant human breast cells. We show that TNF-α or IFN-γ induces IRF-1 in breast cancer cells and results in enhanced cell death. Abrogation of IRF-1 diminishes TNF-α and IFN-γ-induced apoptosis. We test the hypothesis that IRF-1 augments TNF-α-induced apoptosis in breast cancer cells. Potential signaling networks elicited by IRF-1 are investigated by evaluating the NF-κB pathway. TNF-α and/or IFN-γ results in decreased presence of NF-κB p65 in the nucleus of breast cancer cells. While TNF-α and/or IFN-γ can induce IRF-1 in nonmalignant breast cells, a marked change in NF-κB p65 is not observed. Moreover, the ectopic expression of IRF-1 in breast cancer cells results in caspase-3, -7, -8 cleavage, inhibits NF-κB activity, and suppresses the expression of molecules involved in the NF-κB pathway. These data show that IRF-1 in human breast cancer cells elicits multiple signaling networks including intrinsic and extrinsic cell death and down-regulates molecules involved in the NF-κB pathway.

Chopjitt P, Pientong C, Bumrungthai S, et al.
Activities of E6 Protein of Human Papillomavirus 16 Asian Variant on miR-21 Up-regulation and Expression of Human Immune Response Genes.
Asian Pac J Cancer Prev. 2015; 16(9):3961-8 [PubMed] Related Publications
BACKGROUND: Variants of human papillomavirus (HPV) show more oncogenicity than do prototypes. The HPV16 Asian variant (HPV16As) plays a major role in cervical cancer of Asian populations. Some amino acid changes in the E6 protein of HPV16 variants affect E6 functions such as p53 interaction and host immune surveillance. This study aimed to investigate activities of HPV16As E6 protein on modulation of expression of miRNA-21 as well as interferon regulatory factors (IRFs) 1, 3, 7 and c-fos.
MATERIALS AND METHODS: Vectors expressing E6 protein of HPV16As (E6D25E) or HPV16 prototype (E6Pro) were constructed and transfected into C33A cells. HCK1T cells expressing E6D25E or E6Pro were established by transducing retrovirus-containing E6D25E or 16E6Pro. The E6AP-binding activity of E6 and proliferation of the transfected C33A cells were determined. MiR-21 and mRNA of interesting genes were detected in the transfected C33A cells and/or the HCK1T cells, with or without treatment by culture medium from HeLa cells (HeLa-CM).
RESULTS: E6D25E showed binding activity with E6AP similar to that of E6Pro. Interestingly, E6D25E showed a higher activity of miR-21 induction than did E6Pro in C33A cells expressing E6 protein. This result was similar to the HCK1T cells expressing E6 protein, with HeLa-CM treatment. The miR-21 up-regulation significantly corresponded to its target expression. Different levels of expression of IRFs were also observed in the HCK1T cells expressing E6 protein. Interestingly, when treated with HeLa-CM, IRFs 1, 3 and 7 as well as c-fos were significantly suppressed in the HCK1T cells expressing E6D25E, whereas those in the HCK1T cells expressing E6Pro were induced. A similar situation was seen for IFN-α and IFN-β.
CONCLUSIONS: E6D25E of the HPV16As variant differed from the E6 prototype in its activities on epigenetic modulation and immune surveillance and this might be a key factor for the important role of this variant in cervical cancer progression.

Li Z, Chen B, Feng M, et al.
MicroRNA-23b Promotes Avian Leukosis Virus Subgroup J (ALV-J) Replication by Targeting IRF1.
Sci Rep. 2015; 5:10294 [PubMed] Free Access to Full Article Related Publications
Avian leukosis virus subgroup J (ALV-J) can cause several different leukemia-like proliferative diseases in the hemopoietic system of chickens. Here, we investigated the transcriptome profiles and miRNA expression profiles of ALV-J-infected and uninfected chicken spleens to identify the genes and miRNAs related to ALV-J invasion. In total, 252 genes and 167 miRNAs were differentially expressed in ALV-J-infected spleens compared to control uninfected spleens. miR-23b expression was up-regulated in ALV-J-infected spleens compared with the control spleens, and transcriptome analysis revealed that the expression of interferon regulatory factor 1 (IRF1) was down-regulated in ALV-J-infected spleens compared to uninfected spleens. A dual-luciferase reporter assay showed that IRF1 was a direct target of miR-23b. miR-23b overexpression significantly (P = 0.0022) decreased IRF1 mRNA levels and repressed IRF1-3'-UTR reporter activity. In vitro experiments revealed that miR-23b overexpression strengthened ALV-J replication, whereas miR-23b loss of function inhibited ALV-J replication. IRF1 overexpression inhibited ALV-J replication, and IRF1 knockdown enhanced ALV-J replication. Moreover, IRF1 overexpression significantly (P = 0.0014) increased IFN-β expression. In conclusion, these results suggested that miR-23b may play an important role in ALV-J replication by targeting IRF1.

Chen X, Liu L, Mims J, et al.
Analysis of DNA methylation and gene expression in radiation-resistant head and neck tumors.
Epigenetics. 2015; 10(6):545-61 [PubMed] Free Access to Full Article Related Publications
Resistance to radiation therapy constitutes a significant challenge in the treatment of head and neck squamous cell cancer (HNSCC). Alteration in DNA methylation is thought to play a role in this resistance. Here, we analyzed DNA methylation changes in a matched model of radiation resistance for HNSCC using the Illumina HumanMethylation450 BeadChip. Our results show that compared to radiation-sensitive cells (SCC-61), radiation-resistant cells (rSCC-61) had a significant increase in DNA methylation. After combining these results with microarray gene expression data, we identified 84 differentially methylated and expressed genes between these 2 cell lines. Ingenuity Pathway Analysis revealed ILK signaling, glucocorticoid receptor signaling, fatty acid α-oxidation, and cell cycle regulation as top canonical pathways associated with radiation resistance. Validation studies focused on CCND2, a protein involved in cell cycle regulation, which was identified as hypermethylated in the promoter region and downregulated in rSCC-61 relative to SCC-61 cells. Treatment of rSCC-61 and SCC-61 with the DNA hypomethylating agent 5-aza-2'deoxycitidine increased CCND2 levels only in rSCC-61 cells, while treatment with the control reagent cytosine arabinoside did not influence the expression of this gene. Further analysis of HNSCC data from The Cancer Genome Atlas found increased methylation in radiation-resistant tumors, consistent with the cell culture data. Our findings point to global DNA methylation status as a biomarker of radiation resistance in HNSCC, and suggest a need for targeted manipulation of DNA methylation to increase radiation response in HNSCC.

Osborn JL, Greer SF
Metastatic melanoma cells evade immune detection by silencing STAT1.
Int J Mol Sci. 2015; 16(2):4343-61 [PubMed] Free Access to Full Article Related Publications
Transcriptional activation of major histocompatibility complex (MHC) I and II molecules by the cytokine, interferon γ (IFN-γ), is a key step in cell-mediated immunity against pathogens and tumors. Recent evidence suggests that suppression of MHC I and II expression on multiple tumor types plays important roles in tumor immunoevasion. One such tumor is malignant melanoma, a leading cause of skin cancer-related deaths. Despite growing awareness of MHC expression defects, the molecular mechanisms by which melanoma cells suppress MHC and escape from immune-mediated elimination remain unknown. Here, we analyze the dysregulation of the Janus kinase (JAK)/STAT pathway and its role in the suppression of MHC II in melanoma cell lines at the radial growth phase (RGP), the vertical growth phase (VGP) and the metastatic phase (MET). While RGP and VGP cells both express MHC II, MET cells lack not only MHC II, but also the critical transcription factors, interferon response factor (IRF) 1 and its upstream activator, signal transducer and activator of transcription 1 (STAT1). Suppression of STAT1 in vitro was also observed in patient tumor samples, suggesting STAT1 silencing as a global mechanism of MHC II suppression and immunoevasion.

Mao L, Zhang Y, Mo W, et al.
BANF1 is downregulated by IRF1-regulated microRNA-203 in cervical cancer.
PLoS One. 2015; 10(2):e0117035 [PubMed] Free Access to Full Article Related Publications
MicroRNAs (miRNAs) play important roles in various biological processes and are closely associated with the development of cancer. In fact, aberrant expression of miRNAs has been implicated in numerous cancers. In cervical cancer, miR-203 levels are decreased, although the cause of this aberrant expression remains unclear. In this study, we investigate the molecular mechanisms regulating miR-203 gene transcription. We identify the miR-203 transcription start site by 5' rapid amplification of cDNA ends and subsequently identify the miR-203 promoter region. Promoter analysis revealed that IRF1, a transcription factor, regulates miR-203 transcription by binding to the miR-203 promoter. We also demonstrate that miR-203 targets the 3' untranslated region of BANF1, thus downregulating its expression, whereas miR-203 expression is driven by IRF1. MiR-203 is involved in cell cycle regulation and overexpression of miR-203 suppresses cervical cancer cell proliferation, colony formation, migration and invasion. The inhibitory effect of miR-203 on the cancer cells is partially mediated by downregulating its target, BANF1, since knockdown of BANF1 also suppresses colony formation, migration and invasion.

Lin YH, Wu MH, Liao CJ, et al.
Repression of microRNA-130b by thyroid hormone enhances cell motility.
J Hepatol. 2015; 62(6):1328-40 [PubMed] Related Publications
BACKGROUND & AIMS: Thyroid hormone (T3) and its receptor (TR) are involved in cell growth and cancer progression. Although deregulation of microRNA (miRNA) expression has been detected in many tumor types, the mechanisms underlying functional impairment and specific involvement of miRNAs in tumor metastasis remain unclear. In the current study, we aimed to elucidate the involvement of deregulated miRNA-130b (miR-130b) and its target genes mediated by T3/TR in cancer progression.
METHODS: Quantitative reverse transcription-PCR, luciferase and chromatin immunoprecipitation assays were performed to identify the miR-130b transcript and the mechanisms implicated in its regulation. The effects of miR-130b on hepatocellular carcinoma (HCC) invasion were further examined in vitro and in vivo. Clinical correlations among miR-130b, TRs and interferon regulatory factor 1 (IRF1) were examined in HCC samples using Spearman correlation analysis.
RESULTS: Our experiments disclosed negative regulation of miR-130b expression by T3/TR. Overexpression of miR-130b led to marked inhibition of cell migration and invasion, which was mediated via suppression of IRF1. Cell migration ability was promoted by T3, but partially suppressed upon miR-130b overexpression. Furthermore, miR-130b suppressed expression of epithelial-mesenchymal transition (EMT)-related genes, matrix metalloproteinase-9, phosphorylated mammalian target of rapamycin (mTOR), p-ERK1/2, p-AKT and p-signal transducer and activator of transcription (STAT)-3. Notably, miR-130b was downregulated in hepatoma samples and its expression patterns were inversely correlated with those of TRα1 and IRF1.
CONCLUSIONS: Our data collectively highlight a novel pathway interlinking T3/TR, miR-130b, IRF1, the EMT-related genes, p-mTOR, p-STAT3 and the p-AKT cascade, which regulates the motility and invasion of hepatoma cells.

Yuan L, Zhou C, Lu Y, et al.
IFN-γ-mediated IRF1/miR-29b feedback loop suppresses colorectal cancer cell growth and metastasis by repressing IGF1.
Cancer Lett. 2015; 359(1):136-47 [PubMed] Related Publications
To investigate the clinicopathological significance and underlying mechanism of microRNA-29b (miR-29b) in colorectal cancer (CRC), the role of miR-29b was investigated using in vivo and in vitro assays. Luciferase reporter assays were conducted to determine the association between miR-29b and the insulin-like growth factor 1 (IGF1) 3' untranslated region (3'UTR). Chromatin immunoprecipitation (ChIP) assays were employed to assess the direct binding of interferon regulatory factor 1 (IRF1) to miR-29b. We found that interferon (IFN)-γ could induce miR-29b by recruiting IRF1 to binding sites in the miR-29b promoter. A low level of miR-29b was significantly associated with an aggressive phenotype. MiR-29b inhibited CRC cell growth and invasion. IGF1, an activator of PI3K/Akt signaling, was confirmed as a novel target of miR-29b. Moreover, miR-29b increased IRF1 expression, and the inhibition of miR-29b suppressed IFN-γ-induced apoptosis. We elucidated the potential signaling pathway, IFN-γ/IRF1/miR-29b/IGF1, and its implication for CRC tumorigenesis. A positive feedback loop between IRF1 and miR-29b may contribute to the sensitivity of CRC cells to IFN-γ. Targeting miR-29b may provide a strategy for blocking CRC growth and metastasis.

Schwartz-Roberts JL, Cook KL, Chen C, et al.
Interferon regulatory factor-1 signaling regulates the switch between autophagy and apoptosis to determine breast cancer cell fate.
Cancer Res. 2015; 75(6):1046-55 [PubMed] Free Access to Full Article Related Publications
Interferon regulatory factor-1 (IRF1) is a tumor suppressor that regulates cell fate in several cell types. Here, we report an inverse correlation in expression of nuclear IRF1 and the autophagy regulator ATG7 in human breast cancer cells that directly affects their cell fate. In mice harboring mutant Atg7, nuclear IRF1 was increased in mammary tumors, spleen, and kidney. Mechanistic investigations identified ATG7 and the cell death modulator beclin-1 (BECN1) as negative regulators of IRF1. Silencing ATG7 or BECN1 caused estrogen receptor-α to exit the nucleus at the time when IRF1 nuclear localization occurred. Conversely, silencing IRF1 promoted autophagy by increasing BECN1 and blunting IGF1 receptor and mTOR survival signaling. Loss of IRF1 promoted resistance to antiestrogens, whereas combined silencing of ATG7 and IRF1 restored sensitivity to these agents. Using a mathematical model to prompt signaling hypotheses, we developed evidence that ATG7 silencing could resensitize IRF1-attenuated cells to apoptosis through mechanisms that involve other estrogen-regulated genes. Overall, our work shows how inhibiting the autophagy proteins ATG7 and BECN1 can regulate IRF1-dependent and -independent signaling pathways in ways that engender a new therapeutic strategy to attack breast cancer.

AbuSara N, Razavi S, Derwish L, et al.
Restoration of IRF1-dependent anticancer effects by MEK inhibition in human cancer cells.
Cancer Lett. 2015; 357(2):575-81 [PubMed] Related Publications
Interferon regulatory factor (IRF1) is a potent antiviral, antitumor and immune regulatory protein. Recently, we found that activated Ras/MEK inhibits antiviral response by downregulating IRF1 expression and renders cancer cells susceptible to oncolytic viruses. In this study, we sought to determine whether IRF1 downregulation underlies oncogenesis induced by Ras/MEK activation in human cancer cells. Treatment of the MEK inhibitor U0126 promoted IRF1 expression in 7 of 11 cancer cell lines we tested. IRF1 promotion was also observed in human cancer cell lines treated with different MEK inhibitors or with RNAi oligonucleotides against extracellular signal-regulated kinases (ERKs). Restoration of the expression of antitumor genes, p27 and p53 upregulated modulator of apoptosis (PUMA), by MEK inhibition was less in IRF1 shRNA knockdown cancer cells than in vector control cancer cells, suggesting that Ras/MEK targets IRF1 for the downregulation of the antitumor genes. Moreover, apoptosis induction by U0126 was significantly reduced in IRF1 shRNA knockdown cells than vector control cells. This study demonstrates that IRF1 expression is suppressed by activated Ras/MEK in human cancer cells and that IRF1 plays essential roles in apoptosis induced by Ras/MEK inhibition.

Xu Y, Wang W, Gou A, et al.
Effects of suppressor of cytokine signaling 1 silencing on human melanoma cell proliferation and interferon-γ sensitivity.
Mol Med Rep. 2015; 11(1):583-8 [PubMed] Related Publications
The aim of the current study was to observe the effects of suppressor of cytokine signaling 1 (SOCS1) silencing in human melanoma cells on cell biological behavior and interferon-γ (IFN-γ) sensitivity, and to investigate the use of SOCS1 as a therapeutic target in the treatment of melanoma. Western blot analysis and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) were used to verify that SOCS1 interference effectively silenced the expression of SOCS1 in the Mel526 human melanoma cell line. For IFN-γ stimulation, western blot analysis was used to observe changes in expression levels of signal transduction and transcription activator (STAT) 1 and phosphorylated STAT (pSTAT) 1. Changes in the expression levels of IFN-γ regulatory factor 1 (IRF-1) were measured with RT-qPCR. Changes in the sensitivity of melanoma cells to IFN-γ were detected using an MTT assay. The cell proliferation rate was observed by cell counting and changes in the cell cycle were detected with flow cytometry. The results revealed that SOCS1 interference effectively silences SOCS1 expression in Mel526 cells. However, the S stage of the cell cycle was markedly extended. Following the inhibition of SOCS1 expression, the proliferation experiment demonstrated that the proliferation ability of Mel526 cells was decreased. Following IFN-γ stimulation, the expression levels of pSTAT and IRF-1 increased significantly compared with those in the controls. The MTT experiment showed that SOCS1 interference caused the median inhibitory concentration (IC50) of oxaliplatin in Mel526 cells to decrease significantly. In conclusion, SOCS1 interference reduced the proliferation ability of Mel526 human melanoma cells and increased their sensitivity to IFN-γ.

Dou L, Liang HF, Geller DA, et al.
The regulation role of interferon regulatory factor-1 gene and clinical relevance.
Hum Immunol. 2014; 75(11):1110-4 [PubMed] Related Publications
IRF-1, a kind of transcription factors, is expressed constitutively in all cells types except early embryonal cells. By virtue of its interaction with specific DNA sequence, IRF-1 regulates the transcription of a set of target genes which play essential roles in various physiological and pathological processes, including viral infection, tumor immune surveillance, pro-inflammatory injury, development of immunity system. What's more, IRF-1 also interacts with other transcription factors to regulate the specific genes transcription in the nucleus. In immunity system, IRF-1 is suggested to provide a link between innate and adoptive immune system. Although IRF-1 has been demonstrated with essential role in human immunity, the comprehensive understanding of the role of IRF-1 has been restrained because of extensive target genes, Here, we review the clinical relevance of IRF-1 and underlying mechanism based on the latest researches.

Wang YC, Chen CL, Sheu BS, et al.
Helicobacter pylori infection activates Src homology-2 domain-containing phosphatase 2 to suppress IFN-γ signaling.
J Immunol. 2014; 193(8):4149-58 [PubMed] Related Publications
Helicobacter pylori infection not only induces gastric inflammation but also increases the risk of gastric tumorigenesis. IFN-γ has antimicrobial effects; however, H. pylori infection elevates IFN-γ-mediated gastric inflammation and may suppress IFN-γ signaling as a strategy to avoid immune destruction through an as-yet-unknown mechanism. This study was aimed at investigating the mechanism of H. pylori-induced IFN-γ resistance. Postinfection of viable H. pylori decreased IFN-γ-activated signal transducers and activators of transcription 1 and IFN regulatory factor 1 not only in human gastric epithelial MKN45 and AZ-521 but also in human monocytic U937 cells. H. pylori caused an increase in the C-terminal tyrosine phosphorylation of Src homology-2 domain-containing phosphatase (SHP) 2. Pharmacologically and genetically inhibiting SHP2 reversed H. pylori-induced IFN-γ resistance. In contrast to a clinically isolated H. pylori strain HP238, the cytotoxin-associated gene A (CagA) isogenic mutant strain HP238(CagAm) failed to induce IFN-γ resistance, indicating that CagA regulates this effect. Notably, HP238 and HP238(CagAm) differently caused SHP2 phosphorylation; however, imaging and biochemical analyses demonstrated CagA-mediated membrane-associated binding with phosphorylated SHP2. CagA-independent generation of reactive oxygen species (ROS) contributed to H. pylori-induced SHP2 phosphorylation; however, ROS/SHP2 mediated IFN-γ resistance in a CagA-regulated manner. This finding not only provides an alternative mechanism for how CagA and ROS coregulate SHP2 activation but may also explain their roles in H. pylori-induced IFN-γ resistance.

Seo SK, Seo DI, Park WS, et al.
Attenuation of IFN-γ-induced B7-H1 expression by 15-deoxy-delta(12,14)-prostaglandin J2 via downregulation of the Jak/STAT/IRF-1 signaling pathway.
Life Sci. 2014; 112(1-2):82-9 [PubMed] Related Publications
AIM: B7-H1, which belongs to the B7 family of costimulatory molecules, is implicated in the ability of tumors to evade the host immune response. The development of evasion mechanisms within the tumor microenvironment may be responsible for poor therapeutic responses. In this manuscript, we report that the 15-deoxy-δ(12,14)-prostaglandin J2 (15d-PGJ2), peroxisome proliferator-activated receptor gamma (PPARγ) activator leads to the downregulation of the cancer-associated expression of B7-H1 in response to interferon-gamma (IFN-γ) and the associated signaling cascades.
MAIN METHODS: The expression of B7-H1 from IFN-γ-induced B16F10 melanoma cells was measured with flow cytometric analysis. The regulatory mechanisms of 15d-PGJ2 on cellular signaling pathways were examined using Western blot and electrophoretic mobility shift assays.
KEY FINDINGS: The flow cytometric analysis revealed that the B7-H1 costimulatory molecule is significantly upregulated in B16F10 melanoma cells by stimulation with IFN-γ. However, 15d-PGJ2 strongly downregulates B7-H1 expression in IFN-γ-stimulated B16F10 melanoma cells. Furthermore, the significant damping effect of 15d-PGJ2 on B7-H1 expression involves the inhibition of the tyrosine phosphorylation of Janus kinase (Jak) and signal transducer(s) and activator(s) of transcription (STAT) and, thereby, the interferon regulatory factor-1 (IRF-1) trans-activation of STAT. These effects of 15d-PGJ2 were not abrogated by the PPARγ antagonist GW9662, indicating that they occur through a PPARγ-independent mechanism.
SIGNIFICANCE: In this study, we demonstrate that 15d-PGJ2 suppresses the IFN-γ-elicited expression of B7-H1 by the inhibition of IRF-1 transcription via the Jak/STAT signaling pathway through a PPARγ-independent mechanism in mouse melanoma cells.

Cohen S, Mosig R, Moshier E, et al.
Interferon regulatory factor 1 is an independent predictor of platinum resistance and survival in high-grade serous ovarian carcinoma.
Gynecol Oncol. 2014; 134(3):591-8 [PubMed] Related Publications
OBJECTIVE: High-grade serous ovarian cancer (HGSOC) that is resistant to platinum-based chemotherapy has a particularly poor prognosis. Response to platinum has both prognostic survival value and dictates secondary treatment strategies. Using transcriptome analysis, we sought to identify differentially expressed genes/pathways based on a tumor's platinum response for discovering novel predictive biomarkers.
METHODS: Seven primary HGSOC tumor samples, representing two extremes of platinum sensitivity/timing of disease recurrence, were analyzed by RNA-Seq, Ingenuity Pathways Analysis (IPA) and Upstream Regulator Analysis (URA), and used to explore differentially expressed genes and prevalent molecular and cellular processes. Progression-free and overall survival (PFS, OS) was estimated using the Kaplan-Meier method in two different sample sets including GEO and TCGA data sets.
RESULTS: IPA and URA highlighted an IRF1-driven transcriptional program (P=0.0017; z-score of 3.091) in the platinum sensitive improved PFS group. QRT-PCR analysis of 31 HGSOC samples demonstrated a significant difference in PFS between low and high IRF1 expression groups (P=0.048) and between groups that were platinum sensitive versus not (P=0.016). In a larger validation data set, increased levels of IRF1 were associated with both increased PFS (P=0.043) and OS (P=0.019) and the effect on OS was independent of debulking status (optimal debulking, P=0.025; suboptimal, P=0.041).
CONCLUSION: Transcriptome analysis identifies IRF1, a transcription factor that functions both in immune regulation and as a tumor suppressor, as being associated with platinum sensitivity and an independent predictor of both PFS and OS in HGSOC.

Wang J, Ni Z, Duan Z, et al.
Altered expression of hypoxia-inducible factor-1α (HIF-1α) and its regulatory genes in gastric cancer tissues.
PLoS One. 2014; 9(6):e99835 [PubMed] Free Access to Full Article Related Publications
Tissue hypoxia induces reprogramming of cell metabolism and may result in normal cell transformation and cancer progression. Hypoxia-inducible factor 1-alpha (HIF-1α), the key transcription factor, plays an important role in gastric cancer development and progression. This study aimed to investigate the underlying regulatory signaling pathway in gastric cancer using gastric cancer tissue specimens. The integration of gene expression profile and transcriptional regulatory element database (TRED) was pursued to identify HIF-1α ↔ NFκB1 → BRCA1 → STAT3 ← STAT1 gene pathways and their regulated genes. The data showed that there were 82 differentially expressed genes that could be regulated by these five transcription factors in gastric cancer tissues and these genes formed 95 regulation modes, among which seven genes (MMP1, TIMP1, TLR2, FCGR3A, IRF1, FAS, and TFF3) were hub molecules that are regulated at least by two of these five transcription factors simultaneously and were associated with hypoxia, inflammation, and immune disorder. Real-Time PCR and western blot showed increasing of HIF-1α in mRNA and protein levels as well as TIMP1, TFF3 in mRNA levels in gastric cancer tissues. The data are the first study to demonstrate HIF-1α-regulated transcription factors and their corresponding network genes in gastric cancer. Further study with a larger sample size and more functional experiments is needed to confirm these data and then translate into clinical biomarker discovery and treatment strategy for gastric cancer.

Sakai T, Mashima H, Yamada Y, et al.
The roles of interferon regulatory factors 1 and 2 in the progression of human pancreatic cancer.
Pancreas. 2014; 43(6):909-16 [PubMed] Related Publications
OBJECTIVE: Pancreatic cancer is one of the most malignant diseases worldwide. Interferon regulatory factor (IRF) 1 and IRF2 function as a tumor suppressor and oncoprotein, respectively, in several types of cancers. We investigated whether IRF1 and IRF2 are involved in the progression of pancreatic cancer.
METHODS: We examined the expressions of IRF1 and IRF2 in pancreatic cancer specimens and analyzed the association with clinicopathologic features. We evaluated the biological effects of IRF1 and IRF2 using a pancreatic cancer cell line.
RESULTS: The expression levels of IRF1 and IRF2 were decreased and increased, respectively, in the pancreatic cancer cells compared with those observed in the paired normal areas. A higher expression of IRF1 was associated with better features of tumor differentiation, infiltration depth, tumor size, and survival, whereas that of IRF2 was associated with a worse feature of tumor infiltration depth. Interferon regulatory factor 2-overexpressing PANC-1 cells exhibited an increase in cell growth, less apoptotic features, and chemoresistance to gemcitabine treatment. In contrast, IRF1-overexpressing cells exhibited the opposite characteristics.
CONCLUSIONS: Interferon regulatory factors 1 and 2 may regulate the progression of pancreatic cancer by functioning as an antioncoprotein and oncoprotein, respectively. These molecules may serve as potential targets of therapy.

Mauro JA, Blanck G
Functionally distinct gene classes as bigger or smaller transcription factor traps: a possible stochastic component to sequential gene expression programs in cancer.
Gene. 2014; 536(2):398-406 [PubMed] Related Publications
In cancer biology, most molecular regulatory mechanisms are casually treated as on/off switches for specific cancer hallmarks, despite the lack of compelling evidence that cancer hallmarks can be exclusively attributed to specific regulatory proteins. To consider a novel paradigm for the basis of regulating a set of effector genes for proliferation, versus apoptosis-effector genes, we used a bioinformatics approach to ascertain differences between the transcription factor binding site occurrences in the two sets of genes. Results indicated that there are more binding sites per gene, for transcription factors that regulate both proliferation and apoptosis, among the proliferation-effector genes than among the apoptosis-effector genes. Proliferation-effector genes also had more open chromatin regions. We also applied this paradigm to the question of why p53 and interferon regulatory factor-1 (IRF-1) first activate cell cycle arrest genes followed by apoptosis genes, with results indicating the cycle arrest genes are bigger p53 and IRF-1 traps. These data support the idea that, as a set of transcription factors becomes active, there is a stochastic component leading to the accumulation of these transcription factors on genes that effect an initial phenotype before their accumulation on genes that effect a subsequent phenotype.

Yamaoka S, Ito N, Ohka S, et al.
Involvement of the rabies virus phosphoprotein gene in neuroinvasiveness.
J Virol. 2013; 87(22):12327-38 [PubMed] Free Access to Full Article Related Publications
Rabies virus (RABV), which is transmitted via a bite wound caused by a rabid animal, infects peripheral nerves and then spreads to the central nervous system (CNS) before causing severe neurological symptoms and death in the infected individual. Despite the importance of this ability of the virus to spread from a peripheral site to the CNS (neuroinvasiveness) in the pathogenesis of rabies, little is known about the mechanism underlying the neuroinvasiveness of RABV. In this study, to obtain insights into the mechanism, we conducted comparative analysis of two fixed RABV strains, Nishigahara and the derivative strain Ni-CE, which cause lethal and asymptomatic infections, respectively, in mice after intramuscular inoculation. Examination of a series of chimeric viruses harboring the respective genes from Nishigahara in the genetic background of Ni-CE revealed that the Nishigahara phosphoprotein (P) gene plays a major role in the neuroinvasiveness by mediating infection of peripheral nerves. The results obtained from both in vivo and in vitro experiments strongly suggested that the Nishigahara P gene, but not the Ni-CE P gene, is important for stable viral replication in muscle cells. Further investigation based on the previous finding that RABV phosphoprotein counteracts the host interferon (IFN) system demonstrated that the Nishigahara P gene, but not the Ni-CE P gene, functions to suppress expression of the beta interferon (IFN-β) gene (Ifn-β) and IFN-stimulated genes in muscle cells. In conclusion, we provide the first data strongly suggesting that RABV phosphoprotein assists viral replication in muscle cells by counteracting the host IFN system and, consequently, enhances infection of peripheral nerves.

Liu X, Ru J, Zhang J, et al.
miR-23a targets interferon regulatory factor 1 and modulates cellular proliferation and paclitaxel-induced apoptosis in gastric adenocarcinoma cells.
PLoS One. 2013; 8(6):e64707 [PubMed] Free Access to Full Article Related Publications
MicroRNAs are a class of non-coding RNAs that function as key regulators of gene expression at the post-transcriptional level. In our previous research, we found that miR-23a was significantly up-regulated in human gastric adenocarcinoma cells. In the current study, we demonstrate that miR-23a suppresses paclitaxel-induced apoptosis and promotes the cell proliferation and colony formation ability of gastric adenocarcinoma cells. We have identified tumor suppressor interferon regulator factor 1 (IRF1) as a direct target gene of miR-23a. We performed a fluorescent reporter assay to confirm that miR-23a bound to the IRF1 mRNA 3'UTR directly and specifically. The ectopic expression of IRF1 markedly promoted paclitaxel-induced apoptosis and inhibited cell viability and colony formation ability, whereas the knockdown of IRF1 had the opposite effects. The restoration of IRF1 expression counteracted the effects of miR-23a on the paclitaxel-induced apoptosis and cell proliferation of gastric adenocarcinoma cells. Quantitative real-time PCR showed that miR-23a is frequently up-regulated in gastric adenocarcinoma tissues, whereas IRF1 is down-regulated in cancer tissues. Altogether, these results indicate that miR-23a suppresses paclitaxel-induced apoptosis and promotes cell viability and the colony formation ability of gastric adenocarcinoma cells by targeting IRF1 at the post-transcriptional level.

Camicia R, Bachmann SB, Winkler HC, et al.
BAL1/ARTD9 represses the anti-proliferative and pro-apoptotic IFNγ-STAT1-IRF1-p53 axis in diffuse large B-cell lymphoma.
J Cell Sci. 2013; 126(Pt 9):1969-80 [PubMed] Related Publications
The B-aggressive lymphoma-1 protein and ADP-ribosyltransferase BAL1/ARTD9 has been recently identified as a risk-related gene product in aggressive diffuse large B-cell lymphoma (DLBCL). BAL1 is constitutively expressed in a subset of high-risk DLBCLs with an active host inflammatory response and has been suggested to be associated with interferon-related gene expression. Here we identify BAL1 as a novel oncogenic survival factor in DLBCL and show that constitutive overexpression of BAL1 in DLBCL tightly associates with intrinsic interferon-gamma (IFNγ) signaling and constitutive activity of signal transducer and activator of transcription (STAT)-1. Remarkably, BAL1 stimulates the phosphorylation of both STAT1 isoforms, STAT1α and STAT1β, on Y701 and thereby promotes the nuclear accumulation of the antagonistically acting and transcriptionally repressive isoform STAT1β. Moreover, BAL1 physically interacts with both STAT1α and STAT1β through its macrodomains in an ADP-ribosylation-dependent manner. BAL1 directly inhibits, together with STAT1β, the expression of tumor suppressor and interferon response factor (IRF)-1. Conversely, BAL1 enhances the expression of the proto-oncogenes IRF2 and B-cell CLL/lymphoma (BCL)-6 in DLBCL. Our results show for the first time that BAL1 represses the anti-proliferative and pro-apoptotic IFNγ-STAT1-IRF1-p53 axis and mediates proliferation, survival and chemo-resistance in DLBCL. As a consequence constitutive IFNγ-STAT1 signaling does not lead to apoptosis but rather to chemo-resistance in DLBCL overexpressing BAL1. Our results suggest that BAL1 may induce an switch in STAT1 from a tumor suppressor to an oncogene in high-risk DLBCL.

Nazarov PV, Reinsbach SE, Muller A, et al.
Interplay of microRNAs, transcription factors and target genes: linking dynamic expression changes to function.
Nucleic Acids Res. 2013; 41(5):2817-31 [PubMed] Free Access to Full Article Related Publications
MicroRNAs (miRNAs) are ubiquitously expressed small non-coding RNAs that, in most cases, negatively regulate gene expression at the post-transcriptional level. miRNAs are involved in fine-tuning fundamental cellular processes such as proliferation, cell death and cell cycle control and are believed to confer robustness to biological responses. Here, we investigated simultaneously the transcriptional changes of miRNA and mRNA expression levels over time after activation of the Janus kinase/Signal transducer and activator of transcription (Jak/STAT) pathway by interferon-γ stimulation of melanoma cells. To examine global miRNA and mRNA expression patterns, time-series microarray data were analysed. We observed delayed responses of miRNAs (after 24-48 h) with respect to mRNAs (12-24 h) and identified biological functions involved at each step of the cellular response. Inference of the upstream regulators allowed for identification of transcriptional regulators involved in cellular reactions to interferon-γ stimulation. Linking expression profiles of transcriptional regulators and miRNAs with their annotated functions, we demonstrate the dynamic interplay of miRNAs and upstream regulators with biological functions. Finally, our data revealed network motifs in the form of feed-forward loops involving transcriptional regulators, mRNAs and miRNAs. Additional information obtained from integrating time-series mRNA and miRNA data may represent an important step towards understanding the regulatory principles of gene expression.

Pavan S, Olivero M, Corà D, Di Renzo MF
IRF-1 expression is induced by cisplatin in ovarian cancer cells and limits drug effectiveness.
Eur J Cancer. 2013; 49(4):964-73 [PubMed] Related Publications
BACKGROUND: The Interferon Regulatory Factors (IRFs) are transcription factors involved in immune responses and oncogenesis and most of them are classified as tumour suppressors. The expression and activation of IRF(s) are stimulated by several cytokines and by DNA damage. Here we examine the role of the IRF-1 in the response of ovarian cancer cells to the front-line chemotherapeutic drug cisplatin (CDDP).
METHODS: We evaluated the transcriptional response of three ovarian cancer cell lines to CDDP both under control conditions and after IRF-1 silencing using expression microarrays. The role played by IRF-1 in the response of these cells to CDDP was evaluated after silencing and overexpressing IRF-1. We studied cell cycle progression, colony forming ability in monolayer culture and semisolid medium, and apoptosis in the response to the drug.
RESULTS: The treatment of ovarian cancer cells with CDDP boosted the expression and the nuclear translocation of IRF-1, which in turn modulated the expression of putative IRF-1 target genes. Accordingly, IRF-1 silencing re-orchestrated the expression profiles of CDDP-treated cells. In agreement with its role as a tumour suppressor, overexpressing IRF-1 suppressed the transformed phenotype of ovarian cancer cells. Nevertheless, IRF-1 silencing sensitized cells to the apoptotic death induced by CDDP. Over-expression was associated with cell G1 arrest and p21 induction irrespective of p53 proficiency, while IRF-1 silencing reduced the induction of p21 by CDDP.
CONCLUSIONS: These data demonstrate that IRF-1 is up-regulated by CDDP in ovarian cancer cells and might limit the cell response to CDDP, likely by inhibiting cell proliferation. Data suggest that IRF-1 induction might interfere with the effectiveness of combination therapy with platinum drugs and cytokines.

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