IRF8

Gene Summary

Gene:IRF8; interferon regulatory factor 8
Aliases: ICSBP, IRF-8, ICSBP1, IMD32A, IMD32B, H-ICSBP
Location:16q24.1
Summary:Interferon consensus sequence-binding protein (ICSBP) is a transcription factor of the interferon (IFN) regulatory factor (IRF) family. Proteins of this family are composed of a conserved DNA-binding domain in the N-terminal region and a divergent C-terminal region that serves as the regulatory domain. The IRF family proteins bind to the IFN-stimulated response element (ISRE) and regulate expression of genes stimulated by type I IFNs, namely IFN-alpha and IFN-beta. IRF family proteins also control expression of IFN-alpha and IFN-beta-regulated genes that are induced by viral infection. [provided by RefSeq, Jul 2008]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:interferon regulatory factor 8
Source:NCBIAccessed: 11 March, 2017

Ontology:

What does this gene/protein do?
Show (21)

Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 11 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.

  • Cancer Gene Expression Regulation
  • Interferon Regulatory Factors
  • Biomarkers, Tumor
  • Base Sequence
  • Mutation
  • Acute Myeloid Leukaemia
  • Promoter Regions
  • Exome
  • Molecular Sequence Data
  • Case-Control Studies
  • Disease Progression
  • Hematopoietic Stem Cells
  • Stomach Cancer
  • Urothelium
  • Cell Differentiation
  • Apoptosis
  • Down-Regulation
  • Gene Expression Profiling
  • Transfection
  • Epigenetics
  • Transcription Factors
  • Up-Regulation
  • Cancer DNA
  • Western Blotting
  • Signal Transduction
  • Single Nucleotide Polymorphism
  • Immunohistochemistry
  • Knockout Mice
  • Cancer Stem Cells
  • Myeloid Cells
  • HEK293 Cells
  • Leukemic Gene Expression Regulation
  • Tumor Suppressor Gene
  • Messenger RNA
  • Bladder Cancer
  • Chromosome 16
  • Chronic Myelogenous Leukemia
  • Gene Silencing
  • Oligonucleotide Array Sequence Analysis
  • Immunophenotyping
  • DNA Methylation
Tag cloud generated 11 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

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: IRF8 (cancer-related)

Li Y, Cui W, Woodroof JM, Zhang D
Extranodal B Cell Lymphoma with Prominent Spindle Cell Features Arising in Uterus and in Maxillary Sinus: Report of Two Cases and Literature Review.
Ann Clin Lab Sci. 2016; 46(2):213-8 [PubMed] Related Publications
Primary B-cell lymphoma exhibiting a spindle dominant pattern is extremely rare and represents a potential diagnostic pitfall. Here we report two cases of extranodal B cell lymphoma with spindle cell dominant morphology (sp-BCL) of uterus and maxillary sinus. Case 1 was a 54-year-old female with a large mass in the lower uterine segment, inseparable from the wall of the rectum and the urinary bladder. This is the first report of primary sp-BCL arising in the lower uterine segment. Case 2 was a 54-year-old male with a permeative mass involving the maxillary sinus wall with extension into the premaxillary soft tissues. Biopsies of both cases revealed a diffuse infiltration by medium to large atypical spindle cells. A panel of immunohistochemical stains was performed to rule out the possibilities of sarcoma, carcinoma, or melanoma. The final diagnosis was diffuse large B cell lymphoma, germinal center type. This is the first report of sp-BCL incorporating molecular genetic studies and the next-generation sequencing analysis performed on the maxillary lymphoma revealed three genomic alterations in genes of EZH2 (Y646N), IRF8 (S55A), and TNFRSF14 (splice site 304+2T>C). These genes were reported to play important roles in the pathogenesis of diffuse large B cell lymphoma. Both patients achieved complete remission after excision and chemo-radiation therapy despite the extensive local involvement.

Montano G, Ullmark T, Jernmark-Nilsson H, et al.
The hematopoietic tumor suppressor interferon regulatory factor 8 (IRF8) is upregulated by the antimetabolite cytarabine in leukemic cells involving the zinc finger protein ZNF224, acting as a cofactor of the Wilms' tumor gene 1 (WT1) protein.
Leuk Res. 2016; 40:60-7 [PubMed] Related Publications
The transcription factor interferon regulatory factor-8 (IRF8) is highly expressed in myeloid progenitors, while most myeloid leukemias show low or absent expression. Loss of IRF8 in mice leads to a myeloproliferative disorder, indicating a tumor-suppressive role of IRF8. The Wilms tumor gene 1 (WT1) protein represses the IRF8-promoter. The zinc finger protein ZNF224 can act as a transcriptional co-factor of WT1 and potentiate the cytotoxic response to the cytostatic drug cytarabine. We hypothesized that cytarabine upregulates IRF8 and that transcriptional control of IRF8 involves WT1 and ZNF224. Treatment of leukemic K562 cells with cytarabine upregulated IRF8 protein and mRNA, which was correlated to increased expression of ZNF224. Knock down of ZNF224 with shRNA suppressed both basal and cytarabine-induced IRF8 expression. While ZNF224 alone did not affect IRF8 promoter activity, ZNF224 partially reversed the suppressive effect of WT1 on the IRF8 promoter, as judged by luciferase reporter experiments. Coprecipitation revealed nuclear binding of WT1 and ZNF224, and by chromatin immunoprecipitation (ChIP) experiments it was demonstrated that WT1 recruits ZNF224 to the IRF8 promoter. We conclude that cytarabine-induced upregulation of the IRF8 in leukemic cells involves increased levels of ZNF224, which can counteract the repressive activity of WT1 on the IRF8-promoter.

Simon PS, Sharman SK, Lu C, et al.
The NF-κB p65 and p50 homodimer cooperate with IRF8 to activate iNOS transcription.
BMC Cancer. 2015; 15:770 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Inducible nitric oxide synthase (iNOS) metabolizes L-arginine to produce nitric oxide (NO) which was originally identified in myeloid cells as a host defense mechanism against pathogens. Recent studies, however, have revealed that iNOS is often induced in tumor cells and myeloid cells in the tumor microenvironment. Compelling experimental data have shown that iNOS promotes tumor development in certain cellular context and suppresses tumor development in other cellular conditions. The molecular mechanisms underlying these contrasting functions of iNOS is unknown. Because iNOS is often induced by inflammatory signals, it is therefore likely that these contrasting functions of iNOS could be controlled by the inflammatory signaling pathways, which remains to be determined.
METHODS: iNOS is expressed in colon carcinoma and myeloid cells in the tumor microenvironment. Colon carcinoma and myeloid cell lines were used to elucidate the molecular mechanisms underlying iNOS expression. Chromatin immunoprecipitation and electrophoretic mobility shift assay were used to determine the IFNγ-activated pSTAT1 and NF-κB association with the chromatin DNA of the nos2 promoter.
RESULTS: We show here that iNOS is dramatically up-regulated in inflammed human colon tissues and in human colon carcinoma as compared to normal colon tissue. iNOS is expressed in either the colon carcinoma cells or immune cells within the tumor microenvironment. On the molecular level, the proinflammatory IFNγ and NF-κB signals induce iNOS expression in human colon cancer cells. We further demonstrate that NF-κB directly binds to the NOS2 promoter to regulate iNOS expression. Although neither the IFNγ signaling pathway nor the NF-κB signaling pathway alone is sufficient to induce iNOS expression in myeloid cells, IFNγ and NF-κB synergistically induce iNOS expression in myeloid cells. Furthermore, we determine that IFNγ up-regulates IRF8 expression to augment NF-κB induction of iNOS expression. More interestingly, we observed that the p65/p65 and p50/p50 homodimers, not the canonical p65/p50 heterodimer, directly binds to the nos2 promoter to regulate iNOS expression in myeloid cells.
CONCLUSIONS: IFNγ-induced IRF8 acts in concert with NF-κB to regulate iNOS expression in both colon carcinoma and myeloid cells. In myeloid cells, the NF-κB complexes that bind to the nos2 promoter are p65/p65 and p50/p50 homodimers.

Pelish HE, Liau BB, Nitulescu II, et al.
Mediator kinase inhibition further activates super-enhancer-associated genes in AML.
Nature. 2015; 526(7572):273-6 [PubMed] Free Access to Full Article Related Publications
Super-enhancers (SEs), which are composed of large clusters of enhancers densely loaded with the Mediator complex, transcription factors and chromatin regulators, drive high expression of genes implicated in cell identity and disease, such as lineage-controlling transcription factors and oncogenes. BRD4 and CDK7 are positive regulators of SE-mediated transcription. By contrast, negative regulators of SE-associated genes have not been well described. Here we show that the Mediator-associated kinases cyclin-dependent kinase 8 (CDK8) and CDK19 restrain increased activation of key SE-associated genes in acute myeloid leukaemia (AML) cells. We report that the natural product cortistatin A (CA) selectively inhibits Mediator kinases, has anti-leukaemic activity in vitro and in vivo, and disproportionately induces upregulation of SE-associated genes in CA-sensitive AML cell lines but not in CA-insensitive cell lines. In AML cells, CA upregulated SE-associated genes with tumour suppressor and lineage-controlling functions, including the transcription factors CEBPA, IRF8, IRF1 and ETV6 (refs 6-8). The BRD4 inhibitor I-BET151 downregulated these SE-associated genes, yet also has anti-leukaemic activity. Individually increasing or decreasing the expression of these transcription factors suppressed AML cell growth, providing evidence that leukaemia cells are sensitive to the dosage of SE-associated genes. Our results demonstrate that Mediator kinases can negatively regulate SE-associated gene expression in specific cell types, and can be pharmacologically targeted as a therapeutic approach to AML.

Yeh CM, Chen PC, Hsieh HY, et al.
Methylomics analysis identifies ZNF671 as an epigenetically repressed novel tumor suppressor and a potential non-invasive biomarker for the detection of urothelial carcinoma.
Oncotarget. 2015; 6(30):29555-72 [PubMed] Free Access to Full Article Related Publications
The molecular mechanism underlying the lethal phenomenon of urothelial carcinoma (UC) tumor recurrence remains unresolved. Here, by methylation microarray, we identified promoter methylation of the zinc-finger protein gene, ZNF671 in bladder UC tumor tissue samples, a finding that was independently validated by bisulphite pyrosequencing in cell lines and tissue samples. Subsequent assays including treatment with epigenetic depressive agents and in vitro methylation showed ZNF671 methylation to result in its transcriptional repression. ZNF671 re-expression in UC cell lines, via ectopic expression, inhibited tumor growth and invasion, in possible conjunction with downregulation of cancer stem cell markers (c-KIT, NANOG, OCT4). Clinically, high ZNF671 methylation in UC tumor tissues (n=96; 63 bladder, 33 upper urinary tract) associated with tumor grade and poor locoregional disease-free survival. Quantitative MSP analysis in a training (n=97) and test (n=61) sets of voided urine samples from bladder UC patients revealed a sensitivity and specificity of 42%-48% and 89%-92.8%, respectively, for UC cancer detection. Moreover, combining DNA methylation of ZNF671 and 2 other genes (IRF8 and sFRP1) further increased the sensitivity to 96.2%, suggesting a possible three-gene UC biomarker. In summary, ZNF671, an epigenetically silenced novel tumor suppressor, represents a potential predictor for UC relapse and non-invasive biomarker that could assist in UC clinical decision-making.

Strauss L, Sangaletti S, Consonni FM, et al.
RORC1 Regulates Tumor-Promoting "Emergency" Granulo-Monocytopoiesis.
Cancer Cell. 2015; 28(2):253-69 [PubMed] Related Publications
Cancer-driven granulo-monocytopoiesis stimulates expansion of tumor promoting myeloid populations, mostly myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs). We identified subsets of MDSCs and TAMs based on the expression of retinoic-acid-related orphan receptor (RORC1/RORγ) in human and mouse tumor bearers. RORC1 orchestrates myelopoiesis by suppressing negative (Socs3 and Bcl3) and promoting positive (C/EBPβ) regulators of granulopoiesis, as well as the key transcriptional mediators of myeloid progenitor commitment and differentiation to the monocytic/macrophage lineage (IRF8 and PU.1). RORC1 supported tumor-promoting innate immunity by protecting MDSCs from apoptosis, mediating TAM differentiation and M2 polarization, and limiting tumor infiltration by mature neutrophils. Accordingly, ablation of RORC1 in the hematopoietic compartment prevented cancer-driven myelopoiesis, resulting in inhibition of tumor growth and metastasis.

Banik D, Netherby CS, Bogner PN, Abrams SI
MMP3-mediated tumor progression is controlled transcriptionally by a novel IRF8-MMP3 interaction.
Oncotarget. 2015; 6(17):15164-79 [PubMed] Free Access to Full Article Related Publications
Interferon regulatory factor-8 (IRF8), originally identified as a leukemic tumor suppressor, can also exert anti-neoplastic activities in solid tumors. We previously showed that IRF8-loss enhanced tumor growth, which was accompanied by reduced tumor-cell susceptibility to apoptosis. However, the impact of IRF8 expression on tumor growth could not be explained solely by its effects on regulating apoptotic response. Exploratory gene expression profiling further revealed an inverse relationship between IRF8 and MMP3 expression, implying additional intrinsic mechanisms by which IRF8 modulated neoplastic behavior. Although MMP3 expression was originally linked to tumor initiation, the role of MMP3 beyond this stage has remained unclear. Therefore, we hypothesized that MMP3 governed later stages of disease, including progression to metastasis, and did so through a novel IRF8-MMP3 axis. Altogether, we showed an inverse mechanistic relationship between IRF8 and MMP3 expression in tumor progression. Importantly, the growth advantage due to IRF8-loss was significantly compromised after silencing MMP3 expression. Moreover, MMP3-loss reduced spontaneous lung metastasis in an orthotopic mouse model of mammary carcinoma. MMP3 acted, in part, in a cell-intrinsic manner and served as a direct transcriptional target of IRF8. Thus, we identified a novel role of an IRF8-MMP3 axis in tumor progression, which unveils new therapeutic opportunities.

Papaspyridonos M, Matei I, Huang Y, et al.
Id1 suppresses anti-tumour immune responses and promotes tumour progression by impairing myeloid cell maturation.
Nat Commun. 2015; 6:6840 [PubMed] Free Access to Full Article Related Publications
A central mechanism of tumour progression and metastasis involves the generation of an immunosuppressive 'macroenvironment' mediated in part through tumour-secreted factors. Here we demonstrate that upregulation of the Inhibitor of Differentiation 1 (Id1), in response to tumour-derived factors, such as TGFβ, is responsible for the switch from dendritic cell (DC) differentiation to myeloid-derived suppressor cell expansion during tumour progression. Genetic inactivation of Id1 largely corrects the myeloid imbalance, whereas Id1 overexpression in the absence of tumour-derived factors re-creates it. Id1 overexpression leads to systemic immunosuppression by downregulation of key molecules involved in DC differentiation and suppression of CD8 T-cell proliferation, thus promoting primary tumour growth and metastatic progression. Furthermore, advanced melanoma patients have increased plasma TGFβ levels and express higher levels of ID1 in myeloid peripheral blood cells. This study reveals a critical role for Id1 in suppressing the anti-tumour immune response during tumour progression and metastasis.

Hansen MC, Nyvold CG, Roug AS, et al.
Nature and nurture: a case of transcending haematological pre-malignancies in a pair of monozygotic twins adding possible clues on the pathogenesis of B-cell proliferations.
Br J Haematol. 2015; 169(3):391-400 [PubMed] Related Publications
We describe a comprehensive molecular analysis of a pair of monozygotic twins, who came to our attention when one experienced amaurosis fugax and was diagnosed with JAK2+ polycythaemia vera. He (Twin A) was also found to have an asymptomatic B-cell chronic lymphocytic leukaemia (B-CLL). Although JAK2-, Twin B was subsequently shown to have a benign monoclonal B-cell lymphocytosis (MBL). Flow cytometric and molecular analyses of the B-cell compartments revealed different immunoglobulin light and heavy chain usage in each twin. We hypothesized that whole exome sequencing could help delineating the pattern of germline B-cell disorder susceptibility and reveal somatic mutations potentially contributing to the differential patterns of pre-malignancy. Comparing bone marrow cells and T cells and employing in-house engineered integrative analysis, we found aberrations in Twin A consistent with a myeloid neoplasm, i.e. in TET2, RUNX1, PLCB1 and ELF4. Employing the method for detecting high-ranking variants by extensive annotation and relevance scoring, we also identified shared germline variants in genes of proteins interacting with B-cell receptor signalling mediators and the WNT-pathway, including IRF8, PTPRO, BCL9L, SIT1 and SIRPB1, all with possible implications in B-cell proliferation. Similar patterns of IGHV-gene usage to those demonstrated here have been observed in inherited acute lymphoblastic leukaemia. Collectively, these findings may help in facilitating identification of putative master gene(s) involved in B-cell proliferations in general and MBL and B-CLL in particular.

Tamura T, Kurotaki D, Koizumi S
Regulation of myelopoiesis by the transcription factor IRF8.
Int J Hematol. 2015; 101(4):342-51 [PubMed] Related Publications
Interferon regulatory factor-8 (IRF8) is a transcription factor expressed in hematopoietic cells, particularly in mononuclear phagocytes [monocytes/macrophages and dendritic cells (DCs)] and their progenitors. Various studies have demonstrated that IRF8 is essential for the development of monocytes, DCs, eosinophils, and basophils. Conversely, IRF8 suppresses the generation of neutrophils. Accordingly, Irf8 (-/-) mice develop immunodeficiency and a chronic myeloid leukemia (CML)-like disease. Mutations and loss of expression of the human IRF8 gene are also associated with immunodeficiency and CML, respectively. Recent findings have begun to reveal the transcription factor network and epigenetic changes governed by IRF8. For example, in mononuclear phagocyte progenitors, IRF8 cooperates with PU.1 to promote the formation of promoter-distal enhancers to induce monocyte-related genes including the critical downstream transcription factor gene Klf4. On the other hand, IRF8 blocks C/EBPα activity to suppress the neutrophil differentiation program. Indeed, Irf8 (-/-) mononuclear phagocyte progenitors fail to efficiently generate monocytes and DCs and, instead, aberrantly give rise to neutrophils. This article provides an overview of recent advances in our understanding of the role of IRF8 in myelopoiesis and related diseases.

Gao F, Yang Y, Wang Z, et al.
BRAD4 plays a critical role in germinal center response by regulating Bcl-6 and NF-κB activation.
Cell Immunol. 2015; 294(1):1-8 [PubMed] Related Publications
Germinal center (GC) reaction is a T cell-dependent process in which activated B cells undergo clonal expansion and functional maturation to produce high affinity antibodies and differentiate into memory B cells(1). Here we demonstrate a new role of bromodomain and extraterminal domain (BET) protein BRD4 in GC B cell development. We found that during B cell differentiation stage there was an elevated expression of BRD4 in GC B cells and inhibition of BRD4 by small molecule inhibitors led to the suppression of GC formation and correspondent antibody responses in a Td antigen immunization model. At the molecular level, we found that the effects of BRD4 in primary GC B cell differentiation and B cell lymphoma were mediated through the impaired phosphorylation and translocation of NF-κBp65 and further down-regulation of B-cell lymphoma 6 (Bcl6) expression. Thus this study reveals a novel function of BRD4 in controlling the GC B cell development pathway.

Zhang Q, Zhang L, Li L, et al.
Interferon regulatory factor 8 functions as a tumor suppressor in renal cell carcinoma and its promoter methylation is associated with patient poor prognosis.
Cancer Lett. 2014; 354(2):227-34 [PubMed] Related Publications
Interferon regulatory factor 8 (IRF8), as a central element of IFN-γ-signaling, plays a critical role in tumor suppression. However, its expression and underlying molecular mechanism remain elusive in renal cell carcinoma (RCC). Here, we examined IRF8 expression and methylation in RCC cell lines and primary tumors, and further assessed its tumor suppressive functions. We found that IRF8 was widely expressed in human normal tissues including kidney, but frequently downregulated by promoter methylation in RCC cell lines. IRF8 methylation was detected in 25% of primary tumors, but not in adjacent non-malignant renal tissues, and associated with higher tumor nuclear grade of RCC. Ectopic expression of IRF8 inhibited colony formation and migration abilities of RCC cells, through inducing cell cycle G2/M arrest and apoptosis. IFN-γ could induce IRF8 expression in RCC cells, together with increased cleaved-PARP. We further found that IRF8 inhibited expression of oncogenes YAP1 and Survivin, as well as upregulated expression of tumor suppressor genes CASP1, p21 and PTEN. Collectively, our data demonstrate that IRF8 as a functional tumor suppressor is frequently methylated in RCC, and IRF8-mediated interferon signaling is involved in RCC pathogenesis.

Chen Y, Peng C, Abraham SA, et al.
Arachidonate 15-lipoxygenase is required for chronic myeloid leukemia stem cell survival.
J Clin Invest. 2014; 124(9):3847-62 [PubMed] Free Access to Full Article Related Publications
Cancer stem cells (CSCs) are responsible for the initiation and maintenance of some types of cancer, suggesting that inhibition of these cells may limit disease progression and relapse. Unfortunately, few CSC-specific genes have been identified. Here, we determined that the gene encoding arachidonate 15-lipoxygenase (Alox15/15-LO) is essential for the survival of leukemia stem cells (LSCs) in a murine model of BCR-ABL-induced chronic myeloid leukemia (CML). In the absence of Alox15, BCR-ABL was unable to induce CML in mice. Furthermore, Alox15 deletion impaired LSC function by affecting cell division and apoptosis, leading to an eventual depletion of LSCs. Moreover, chemical inhibition of 15-LO function impaired LSC function and attenuated CML in mice. The defective CML phenotype in Alox15-deficient animals was rescued by depleting the gene encoding P-selectin, which is upregulated in Alox15-deficient animals. Both deletion and overexpression of P-selectin affected the survival of LSCs. In human CML cell lines and CD34+ cells, knockdown of Alox15 or inhibition of 15-LO dramatically reduced survival. Loss of Alox15 altered expression of PTEN, PI3K/AKT, and the transcription factor ICSBP, which are known mediators of cancer pathogenesis. These results suggest that ALOX15 has potential as a therapeutic target for eradicating LSCs in CML.

Sharma A, Yun H, Jyotsana N, et al.
Constitutive IRF8 expression inhibits AML by activation of repressed immune response signaling.
Leukemia. 2015; 29(1):157-68 [PubMed] Related Publications
Myeloid differentiation is blocked in acute myeloid leukemia (AML), but the molecular mechanisms are not well characterized. Meningioma 1 (MN1) is overexpressed in AML patients and confers resistance to all-trans retinoic acid-induced differentiation. To understand the role of MN1 as a transcriptional regulator in myeloid differentiation, we fused transcriptional activation (VP16) or repression (M33) domains with MN1 and characterized these cells in vivo. Transcriptional activation of MN1 target genes induced myeloproliferative disease with long latency and differentiation potential to mature neutrophils. A large proportion of differentially expressed genes between leukemic MN1 and differentiation-permissive MN1VP16 cells belonged to the immune response pathway like interferon-response factor (Irf) 8 and Ccl9. As MN1 is a cofactor of MEIS1 and retinoic acid receptor alpha (RARA), we compared chromatin occupancy between these genes. Immune response genes that were upregulated in MN1VP16 cells were co-targeted by MN1 and MEIS1, but not RARA, suggesting that myeloid differentiation is blocked through transcriptional repression of shared target genes of MN1 and MEIS1. Constitutive expression of Irf8 or its target gene Ccl9 identified these genes as potent inhibitors of murine and human leukemias in vivo. Our data show that MN1 prevents activation of the immune response pathway, and suggest restoration of IRF8 signaling as therapeutic target in AML.

Dzikiewicz-Krawczyk A, Macieja A, Mały E, et al.
Polymorphisms in microRNA target sites modulate risk of lymphoblastic and myeloid leukemias and affect microRNA binding.
J Hematol Oncol. 2014; 7:43 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: MicroRNA dysregulation is a common event in leukemia. Polymorphisms in microRNA-binding sites (miRSNPs) in target genes may alter the strength of microRNA interaction with target transcripts thereby affecting protein levels. In this study we aimed at identifying miRSNPs associated with leukemia risk and assessing impact of these miRSNPs on miRNA binding to target transcripts.
METHODS: We analyzed with specialized algorithms the 3' untranslated regions of 137 leukemia-associated genes and identified 111 putative miRSNPs, of which 10 were chosen for further investigation. We genotyped patients with acute myeloid leukemia (AML, n = 87), chronic myeloid leukemia (CML, n = 140), childhood acute lymphoblastic leukemia (ALL, n = 101) and healthy controls (n = 471). Association between SNPs and leukemia risk was calculated by estimating odds ratios in the multivariate logistic regression analysis. For miRSNPs that were associated with leukemia risk we performed luciferase reporter assays to examine whether they influence miRNA binding.
RESULTS: Here we show that variant alleles of TLX1_rs2742038 and ETV6_rs1573613 were associated with increased risk of childhood ALL (OR (95% CI) = 3.97 (1.43-11.02) and 1.9 (1.16-3.11), respectively), while PML_rs9479 was associated with decreased ALL risk (OR = 0.55 (0.36-0.86). In adult myeloid leukemias we found significant associations between the variant allele of PML_rs9479 and decreased AML risk (OR = 0.61 (0.38-0.97), and between variant alleles of IRF8_ rs10514611 and ARHGAP26_rs187729 and increased CML risk (OR = 2.4 (1.12-5.15) and 1.63 (1.07-2.47), respectively). Moreover, we observed a significant trend for an increasing ALL and CML risk with the growing number of risk genotypes with OR = 13.91 (4.38-44.11) for carriers of ≥3 risk genotypes in ALL and OR = 4.9 (1.27-18.85) for carriers of 2 risk genotypes in CML. Luciferase reporter assays revealed that the C allele of ARHGAP26_rs187729 creates an illegitimate binding site for miR-18a-3p, while the A allele of PML_rs9479 enhances binding of miR-510-5p and the C allele of ETV6_rs1573613 weakens binding of miR-34c-5p and miR-449b-5p.
CONCLUSIONS: Our study implicates that microRNA-binding site polymorphisms modulate leukemia risk by interfering with the miRNA-mediated regulation. Our findings underscore the significance of variability in 3' untranslated regions in leukemia.

Sung JY, Park SY, Kim JH, et al.
Interferon consensus sequence-binding protein (ICSBP) promotes epithelial-to-mesenchymal transition (EMT)-like phenomena, cell-motility, and invasion via TGF-β signaling in U2OS cells.
Cell Death Dis. 2014; 5:e1224 [PubMed] Free Access to Full Article Related Publications
Interferon consensus sequence-binding protein (ICSBP) is a transcription factor induced by interferon gamma (IFN-γ) and a member of the interferon regulatory factor (IRF) family. ICSBP is predominantly expressed in hematopoietic cells and regulates the immune response and cell growth and differentiation. However, little is known about its function in non-hematopoietic cells. Here we show a novel function for ICSBP in epithelial-to-mesenchymal transition (EMT)-like phenomena (ELP), cell motility, and invasion in human osteosarcoma cell lines, including U2OS cells. IFN-γ treatment induced ICSBP expression and EMT-like morphological change in U2OS cells, which were suppressed by ICSBP knockdown. To further investigate the role of ICSBP in ELP, we established a stable U2OS cell line that overexpresses ICSBP. ICSBP expression caused U2OS cells to have a more elongated shape and an increased vimentin and fibronectin expression. ICSBP expression also promoted adhesiveness, motility, and invasiveness of U2OS cells. ICSBP upregulated transforming growth factor (TGF)-β receptors and activated TGF-β signaling cascades, which were responsible for ELP as well as increased cell motility and invasion. In addition, ICSBP-induced TGF-β receptor activation resulted in the upregulation of Snail. Knockdown of Snail attenuated the ICSBP-induced augmentation of cell motility and invasion. Upregulation of Snail, ELP, and increased invasion by ICSBP expression were also observed in other osteosarcoma cell lines, such as Saos-2 and 143B. Furthermore, ICSBP and TGF-β receptor I were expressed in 45/54 (84%) and 47/54 (87%) of human osteosarcoma tissues, respectively, and showed significant correlation (r=0.47, P=0.0007) with respect to their expression levels. Taken altogether, these data demonstrate a novel function for ICSBP in ELP, cell motility, and invasion through the TGF-β and Snail signaling pathways.

Waight JD, Banik D, Griffiths EA, et al.
Regulation of the interferon regulatory factor-8 (IRF-8) tumor suppressor gene by the signal transducer and activator of transcription 5 (STAT5) transcription factor in chronic myeloid leukemia.
J Biol Chem. 2014; 289(22):15642-52 [PubMed] Free Access to Full Article Related Publications
Tyrosine kinase inhibitors such as imatinib can effectively target the BCR-ABL oncoprotein in a majority of patients with chronic myeloid leukemia (CML). Unfortunately, some patients are resistant primarily to imatinib and others develop drug resistance, prompting interest in the discovery of new drug targets. Although much of this resistance can be explained by the presence of mutations within the tyrosine kinase domain of BCR-ABL, such mutations are not universally identified. Interferon regulatory factor-8 (IRF-8) is a transcription factor that is essential for myelopoiesis. Depressed IRF-8 levels are observed in a majority of CML patients and Irf-8(-/-) mice exhibit a CML-like disease. The underlying mechanisms of IRF-8 loss in CML are unknown. We hypothesized that BCR-ABL suppresses transcription of IRF-8 through STAT5, a proximal BCR-ABL target. Treatment of primary cells from newly diagnosed CML patients in chronic phase as well as BCR-ABL(+) cell lines with imatinib increased IRF-8 transcription. Furthermore, IRF-8 expression in cell line models was necessary for imatinib-induced antitumor responses. We have demonstrated that IRF-8 is a direct target of STAT5 and that silencing of STAT5 induced IRF-8 expression. Conversely, activating STAT5 suppressed IRF-8 transcription. Finally, we showed that STAT5 blockade using a recently discovered antagonist increased IRF-8 expression in patient samples. These data reveal a previously unrecognized BCR-ABL-STAT5-IRF-8 network, which widens the repertoire of potentially new anti-CML targets.

Li H, Kaminski MS, Li Y, et al.
Mutations in linker histone genes HIST1H1 B, C, D, and E; OCT2 (POU2F2); IRF8; and ARID1A underlying the pathogenesis of follicular lymphoma.
Blood. 2014; 123(10):1487-98 [PubMed] Free Access to Full Article Related Publications
Follicular lymphoma (FL) constitutes the second most common non-Hodgkin lymphoma in the western world. FL carries characteristic recurrent structural genomic aberrations. However, information regarding the coding genome in FL is still evolving. Here, we describe the results of massively parallel exome sequencing and single nucleotide polymorphism 6.0 array genomic profiling of 11 highly purified FL cases, and 1 transformed FL case and the validation of selected mutations in 102 FL cases. We report the identification of 15 novel recurrently mutated genes in FL. These include frequent mutations in the linker histone genes HIST1H1 B-E (27%) and mutations in OCT2 (also known as POU2F2; 8%), IRF8 (6%), and ARID1A (11%). A subset of the mutations in HIST1H1 B-E affected binding to DNMT3B, and mutations in HIST1H1 B-E and in EZH2 or ARID1A were largely mutually exclusive, implicating HIST1H1 B-E in epigenetic deregulation in FL. Mutations in OCT2 (POU2F2) affected its transcriptional and functional properties as measured through luciferase assays, the biological analysis of stably transduced cell lines, and global expression profiling. Finally, multiple novel mutated genes located within regions of acquired uniparental disomy in FL are identified. In aggregate, these data substantially broaden our understanding of the genomic pathogenesis of FL.

Scheller M, Schönheit J, Zimmermann K, et al.
Cross talk between Wnt/β-catenin and Irf8 in leukemia progression and drug resistance.
J Exp Med. 2013; 210(11):2239-56 [PubMed] Free Access to Full Article Related Publications
Progression and disease relapse of chronic myeloid leukemia (CML) depends on leukemia-initiating cells (LIC) that resist treatment. Using mouse genetics and a BCR-ABL model of CML, we observed cross talk between Wnt/β-catenin signaling and the interferon-regulatory factor 8 (Irf8). In normal hematopoiesis, activation of β-catenin results in up-regulation of Irf8, which in turn limits oncogenic β-catenin functions. Self-renewal and myeloproliferation become dependent on β-catenin in Irf8-deficient animals that develop a CML-like disease. Combined Irf8 deletion and constitutive β-catenin activation result in progression of CML into fatal blast crisis, elevated leukemic potential of BCR-ABL-induced LICs, and Imatinib resistance. Interestingly, activated β-catenin enhances a preexisting Irf8-deficient gene signature, identifying β-catenin as an amplifier of progression-specific gene regulation in the shift of CML to blast crisis. Collectively, our data uncover Irf8 as a roadblock for β-catenin-driven leukemia and imply both factors as targets in combinatorial therapy.

Waight JD, Netherby C, Hensen ML, et al.
Myeloid-derived suppressor cell development is regulated by a STAT/IRF-8 axis.
J Clin Invest. 2013; 123(10):4464-78 [PubMed] Free Access to Full Article Related Publications
Myeloid-derived suppressor cells (MDSCs) comprise immature myeloid populations produced in diverse pathologies, including neoplasia. Because MDSCs can impair antitumor immunity, these cells have emerged as a significant barrier to cancer therapy. Although much research has focused on how MDSCs promote tumor progression, it remains unclear how MDSCs develop and why the MDSC response is heavily granulocytic. Given that MDSCs are a manifestation of aberrant myelopoiesis, we hypothesized that MDSCs arise from perturbations in the regulation of interferon regulatory factor-8 (IRF-8), an integral transcriptional component of myeloid differentiation and lineage commitment. Overall, we demonstrated that (a) Irf8-deficient mice generated myeloid populations highly homologous to tumor-induced MDSCs with respect to phenotype, function, and gene expression profiles; (b) IRF-8 overexpression in mice attenuated MDSC accumulation and enhanced immunotherapeutic efficacy; (c) the MDSC-inducing factors G-CSF and GM-CSF facilitated IRF-8 downregulation via STAT3- and STAT5-dependent pathways; and (d) IRF-8 levels in MDSCs of breast cancer patients declined with increasing MDSC frequency, implicating IRF-8 as a negative regulator in human MDSC biology. Together, our results reveal a previously unrecognized role for IRF-8 expression in MDSC subset development, which may provide new avenues to target MDSCs in neoplasia.

Pogosova-Agadjanyan EL, Kopecky KJ, Ostronoff F, et al.
The prognostic significance of IRF8 transcripts in adult patients with acute myeloid leukemia.
PLoS One. 2013; 8(8):e70812 [PubMed] Free Access to Full Article Related Publications
Interferon regulatory factor 8 (IRF8) is a transcription factor that plays a critical role in normal hematopoiesis, such that disruption of IRF8 activity promotes leukemogenesis. We and others have identified aberrant expression of IRF8 transcripts, including novel splice variants, in acute myeloid leukemia (AML), but studies have not investigated the prognostic significance of these transcripts. Therefore, we developed and optimized quantitative expression assays for both, the wild type, or the reference sequence (WT-IRF8) and novel splice variants (SV-IRF8). These assays were used to quantify IRF8 transcript levels in 194 adult patients with AML, and multivariate analyses investigated the prognostic significance of these expression levels. After adjusting for known prognostic factors, expression levels of WT- or SV-IRF8 transcripts were not significantly associated with complete responses or overall survival. However, increased expression of WT-IRF8 was associated with decreased relapse-free survival (RFS) in both univariate (P = 0.010) and multivariate (P = 0.019) analyses. Similarly, increased expression of SV-IRF8 was associated with a decreased RFS (univariate, P = 0.026 and multivariate, P = 0.021). These studies show for the first time that WT-IRF8 and SV-IRF8 are independent adverse prognostic factors for patients with AML. Additional studies are planned to examine the prognostic significance of IRF8 transcripts in other populations of AML patients.

Bouamar H, Abbas S, Lin AP, et al.
A capture-sequencing strategy identifies IRF8, EBF1, and APRIL as novel IGH fusion partners in B-cell lymphoma.
Blood. 2013; 122(5):726-33 [PubMed] Free Access to Full Article Related Publications
The characterization of immunoglobulin heavy chain (IGH) translocations provides information on the diagnosis and guides therapeutic decisions in mature B-cell malignancies while enhancing our understanding of normal and malignant B-cell biology. However, existing methodologies for the detection of IGH translocations are labor intensive, often require viable cells, and are biased toward known IGH fusions. To overcome these limitations, we developed a capture sequencing strategy for the identification of IGH rearrangements at nucleotide level resolution and tested its capabilities as a diagnostic and discovery tool in 78 primary diffuse large B-cell lymphomas (DLBCLs). We readily identified IGH-BCL2, IGH-BCL6, IGH-MYC, and IGH-CCND1 fusions and discovered IRF8, EBF1, and TNFSF13 (APRIL) as novel IGH partners in these tumors. IRF8 and TNFSF13 expression was significantly higher in lymphomas with IGH rearrangements targeting these loci. Modeling the deregulation of IRF8 and EBF1 in vitro defined a lymphomagenic profile characterized by up-regulation of AID and/or BCL6, down-regulation of PRMD1, and resistance to apoptosis. Using a capture sequencing strategy, we discovered the B-cell relevant genes IRF8, EBF1, and TNFSF13 as novel targets for IGH deregulation. This methodology is poised to change how IGH translocations are identified in clinical settings while remaining a powerful tool to uncover the pathogenesis of B-cell malignancies.

Hu X, Bardhan K, Paschall AV, et al.
Deregulation of apoptotic factors Bcl-xL and Bax confers apoptotic resistance to myeloid-derived suppressor cells and contributes to their persistence in cancer.
J Biol Chem. 2013; 288(26):19103-15 [PubMed] Free Access to Full Article Related Publications
Myeloid-derived suppressor cells (MDSCs) are heterogeneous immature myeloid cells that accumulate in response to tumor progression. Compelling data from mouse models and human cancer patients showed that tumor-induced inflammatory mediators induce MDSC differentiation. However, the mechanisms underlying MDSC persistence is largely unknown. Here, we demonstrated that tumor-induced MDSCs exhibit significantly decreased spontaneous apoptosis as compared with myeloid cells with the same phenotypes from tumor-free mice. Consistent with the decreased apoptosis, cell surface Fas receptor decreased significantly in tumor-induced MDSCs. Screening for changes of key apoptosis mediators downstream the Fas receptor revealed that expression levels of IRF8 and Bax are diminished, whereas expression of Bcl-xL is increased in tumor-induced MDSCs. We further determined that IRF8 binds directly to Bax and Bcl-x promoter in primary myeloid cells in vivo, and IRF8-deficient MDSC-like cells also exhibit increased Bcl-xL and decreased Bax expression. Analysis of CD69 and CD25 levels revealed that cytotoxic T lymphocytes (CTLs) are partially activated in tumor-bearing hosts. Strikingly, FasL but not perforin and granzymes were selectively activated in CTLs in the tumor-bearing host. ABT-737 significantly increased the sensitivity of MDSCs to Fas-mediated apoptosis in vitro. More importantly, ABT-737 therapy increased MDSC spontaneous apoptosis and decreased MDSC accumulation in tumor-bearing mice. Our data thus determined that MDSCs use down-regulation of IRF8 to alter Bax and Bcl-xL expression to deregulate the Fas-mediated apoptosis pathway to evade elimination by host CTLs. Therefore, targeting Bcl-xL is potentially effective in suppression of MDSC persistence in cancer therapy.

Tinguely M, Thies S, Frigerio S, et al.
IRF8 is associated with germinal center B-cell-like type of diffuse large B-cell lymphoma and exceptionally involved in translocation t(14;16)(q32.33;q24.1).
Leuk Lymphoma. 2014; 55(1):136-42 [PubMed] Related Publications
Chromosomal translocations involving the immunoglobulin loci represent frequent oncogenic events in B-cell lymphoma development. Although IRF8 (ICSBP-1) protein expression has been demonstrated in germinal center B-cells and related lymphomas in a single report, the IRF8 gene was not described as an immunoglobulin heavy chain (IGH) translocation partner. In a discovery-driven approach we searched for new translocation partners of IGH in diffuse large B-cell lymphoma (DLBCL) by long distance inverse polymerase chain reaction (LDI-PCR) and Sanger sequencing. A t(14;16)(q32.33;q24.1) IGH/IRF8 was detected in a CD5+de novo DLBCL, confirmed by translocation specific PCR and fluorescence in situ hybridization (FISH) analysis. No further IRF8 aberration could be identified either by LDI-PCR in an additional five CD5+DLBCLs or by FISH on 78 formalin-fixed paraffin-embedded biopsies. Subsequent screening for IRF8 by immunohistochemistry revealed IRF8 expression in 18/78 (23%), correlating with a germinal center B-cell-like (GCB) type of DLBCL. This hitherto unknown translocation t(14;16)(q32.33;q24.1) is likely to represent the initiator of a multistep lymphomagenesis in a CD5+de novo DLBCL.

Mattei F, Schiavoni G, Sestili P, et al.
IRF-8 controls melanoma progression by regulating the cross talk between cancer and immune cells within the tumor microenvironment.
Neoplasia. 2012; 14(12):1223-35 [PubMed] Free Access to Full Article Related Publications
The transcription factor interferon regulatory factor-8 (IRF-8) is crucial for myeloid cell development and immune response and also acts as a tumor suppressor gene. Here, we analyzed the role of IRF-8 in the cross talk between melanoma cells and tumor-infiltrating leukocytes. B16-F10 melanoma cells transplanted into IRF-8-deficient (IRF-8(-/-)) mice grow more rapidly, leading to higher numbers of lung metastasis, with respect to control animals. These events correlated with reduced dendritic cell and T cell infiltration, accumulation of myeloid-derived suppressor cells and a chemokine/chemokine receptor expression profile within the tumor microenvironment supporting tumor growth, angiogenesis, and metastasis. Noticeably, primary tumors developing in IRF-8(-/-) mice displayed a clear-cut inhibition of IRF-8 expression in melanoma cells. Injection of the demethylating agent 5-aza-2'-deoxycytidine into melanoma-bearing IRF-8(-/-) animals induced intratumoral IRF-8 expression and resulted in the re-establishment of a chemokine/ chemokine receptor pattern favoring leukocyte infiltration and melanoma growth arrest. Importantly, intrinsic IRF-8 expression was progressively down-modulated during melanoma growth in mice and in human metastatic melanoma cells with respect to primary tumors. Lastly, IRF-8 expression in melanoma cells was directly modulated by soluble factors, among which interleukin-27 (IL-27), released by immune cells from tumor-bearing mice. Collectively, these results underscore a key role of IRF-8 in the cross talk between melanoma and immune cells, thus revealing its critical function within the tumor microenvironment in regulating melanoma progression and invasiveness.

Slager SL, Achenbach SJ, Asmann YW, et al.
Mapping of the IRF8 gene identifies a 3'UTR variant associated with risk of chronic lymphocytic leukemia but not other common non-Hodgkin lymphoma subtypes.
Cancer Epidemiol Biomarkers Prev. 2013; 22(3):461-6 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Our genome-wide association study (GWAS) of chronic lymphocytic leukemia (CLL) identified 4 highly correlated intronic variants within the IRF8 gene that were associated with CLL. These results were further supported by a recent meta-analysis of our GWAS with two other GWAS of CLL, supporting the IRF8 gene as a strong candidate for CLL risk.
METHODS: To refine the genetic association of CLL risk, we conducted Sanger sequencing of IRF8 in 94 CLL cases and 96 controls. We then conducted fine mapping by genotyping 39 variants (of which 10 were identified from sequencing) in 745 CLL cases and 1,521 controls. We also assessed these associations with risk of other non-Hodgkin lymphoma (NHL) subtypes.
RESULTS: The strongest association with CLL risk was observed with a common single-nucleotide polymorphism (SNP) located within the 3' untranslated region (UTR) of IRF8 (rs1044873, log additive OR = 0.7, P = 1.81 × 10(-6)). This SNP was not associated with the other NHL subtypes (all P > 0.05).
CONCLUSIONS: We provide evidence that rs1044873 in the IRF8 gene accounts for the initial GWAS signal for CLL risk. This association appears to be unique to CLL with little support for association with other common NHL subtypes. Future work is needed to assess functional role of IRF8 in CLL etiology.
IMPACT: These data provide support that a functional variant within the 3'UTR of IRF8 may be driving the GWAS signal seen on 16q24.1 for CLL risk.

Zhang J, Grubor V, Love CL, et al.
Genetic heterogeneity of diffuse large B-cell lymphoma.
Proc Natl Acad Sci U S A. 2013; 110(4):1398-403 [PubMed] Free Access to Full Article Related Publications
Diffuse large B-cell lymphoma (DLBCL) is the most common form of lymphoma in adults. The disease exhibits a striking heterogeneity in gene expression profiles and clinical outcomes, but its genetic causes remain to be fully defined. Through whole genome and exome sequencing, we characterized the genetic diversity of DLBCL. In all, we sequenced 73 DLBCL primary tumors (34 with matched normal DNA). Separately, we sequenced the exomes of 21 DLBCL cell lines. We identified 322 DLBCL cancer genes that were recurrently mutated in primary DLBCLs. We identified recurrent mutations implicating a number of known and not previously identified genes and pathways in DLBCL including those related to chromatin modification (ARID1A and MEF2B), NF-κB (CARD11 and TNFAIP3), PI3 kinase (PIK3CD, PIK3R1, and MTOR), B-cell lineage (IRF8, POU2F2, and GNA13), and WNT signaling (WIF1). We also experimentally validated a mutation in PIK3CD, a gene not previously implicated in lymphomas. The patterns of mutation demonstrated a classic long tail distribution with substantial variation of mutated genes from patient to patient and also between published studies. Thus, our study reveals the tremendous genetic heterogeneity that underlies lymphomas and highlights the need for personalized medicine approaches to treating these patients.

Lin HY, Huang TT, Lee MS, et al.
Unexpected close surgical margin in resected buccal cancer: very close margin and DAPK promoter hypermethylation predict poor clinical outcomes.
Oral Oncol. 2013; 49(4):336-44 [PubMed] Related Publications
OBJECTIVES: In resected buccal cancer patients, an unexpected close surgical margin has been observed to correlate with poor clinical outcomes. However, close surgical margin alone does not independently guide post-operative therapies, revealing a clinical debate. Hence, the present study intended to explore epigenetic-based bio-predictors for further stratifying this debating patient population.
MATERIALS AND METHODS: Between 2000 and 2008, we retrospectively recruited 44 resected buccal cancer patients with a close surgical margin of ≤5 mm. All patients had post-operative radiotherapy. Genomic DNA was extracted from tumor-enrich areas that contained cancer cells of >70%. Methylation-specific PCR was performed to detect promoter methylation of four tumor suppressor genes, including RASSF1A, DAPK, IRF8, and SFRP1. Post-irradiation locoregional control was defined as the primary end point.
RESULTS: There were 40 males and 4 females, with a median age of 53.5 years (range, 32-82 years). Multivariate analysis identified two independent predictors for locoregional recurrence: very close margin of ≤1 mm (HR: 4.96; 95% CI, 1.63-15.09; P=0.018) and promoter hypermethylation of DAPK (HR: 2.83; 95% CI, 1.05-7.63; P=0.042). The highest risk of locoregional recurrence was observed in patients with both of the two factors (HR, 8.05; 95% CI, 2.56-25.82; P=0.002) when compared with patients with none. Shorter disease-free survival, but not overall survival, was also observed.
CONCLUSION: More aggressive managements should be considered in resected buccal cancer patients with both very close margin and DAPK promoter hypermethylation rather than post-operative observation or radiotherapy alone.

Eto M, Kamba T, Miyake H, et al.
STAT3 polymorphism can predict the response to interferon-α therapy in patients with metastatic renal cell carcinoma.
Eur Urol. 2013; 63(4):745-52 [PubMed] Related Publications
BACKGROUND: In our 2007 retrospective study, we reported that single nucleotide polymorphisms (SNPs) in the signal transducer and activator of transcription 3 (acute-phase response factor) (STAT3) gene were significantly associated with better response to interferon (IFN)-α in patients with metastatic renal cell carcinoma (mRCC).
OBJECTIVE: To prospectively confirm those results, the Japan Immunotherapy SNPs-Study Group for Kidney Cancer conducted this trial.
DESIGN, SETTING, AND PARTICIPANTS: In this multicenter, prospective study, 203 eligible patients were enrolled. We evaluated the correlation between the antitumor effects of IFN-α and 11 SNPs (STAT3-2, STAT3-0, SOCS3-1, IL4R-34, PTGS1-3, PTGS1-4, PTGS1-5, PTGS2-12, IRF2-67, ICSBP-38, and TAP2-5) in eight genes in 180 patients who received IFN-α for >12 wk.
INTERVENTIONS: Patients were treated with three doses per week of IFN-α 5 million IU.
OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: We analyzed the association of response to IFN-α and overall survival (OS) with genetic polymorphisms using a chi-square test and a logistic regression model.
RESULTS AND LIMITATIONS: The response rate of IFN-α was 13.8% (28 of 203 patients; 9 complete responses [CRs], 19 partial responses [PRs]). The CR rate of 4.4% was higher than we expected. Response to IFN-α was not associated with any of the 11 SNPs examined. However, when we assessed patients with CR, PR, and stable disease >24 wk as a group representing those with clinical response, a significant association was observed between STAT3-2 (rs1905341) and the clinical response of IFN-α (p=0.039). Namely, C/C genotype of STAT3-2 was significantly associated with the clinical response of IFN-α and OS. These results were generated in Japanese patients and should be studied in other ethnic groups.
CONCLUSIONS: This is the first prospective study demonstrating that a STAT3 polymorphism can be a predictive marker for treatment with IFN-α for patients with mRCC.

Zimmerman MA, Rahman NT, Yang D, et al.
Unphosphorylated STAT1 promotes sarcoma development through repressing expression of Fas and bad and conferring apoptotic resistance.
Cancer Res. 2012; 72(18):4724-32 [PubMed] Free Access to Full Article Related Publications
STAT1 exists in phosphorylated (pSTAT1) and unphosphorylated (uSTAT1) forms each regulated by IFN-γ. Although STAT1 is a key mediator of the IFN-γ signaling pathway, an essential component of the host cancer immunosurveillance system, STAT1 is also overexpressed in certain human cancers where the functions of pSTAT1 and uSTAT1 are ill defined. Using a murine model of soft tissue sarcoma (STS), we show that disruption of the IFN effector molecule IRF8 decreases pSTAT1 and increases uSTAT1 in STS cells, thereby increasing their metastatic potential. We determined that the IRF8 gene promoter was hypermethylated frequently in human STS. An analysis of 123 human STS specimens revealed that high uSTAT1 levels in tumor cells was correlated with a reduction in disease-specific survival (DSS), whereas high pSTAT1 levels in tumor cells were correlated with an increase in DSS. In addition, uSTAT1 levels were negatively correlated with pSTAT1 levels in these STS specimens. Mechanistic investigations revealed that IRF8 suppressed STAT1 transcription by binding the STAT1 promoter. RNAi-mediated silencing of STAT1 in STS cells was sufficient to increase expression of the apoptotic mediators Fas and Bad and to elevate the sensitivity of STS cells to Fas-mediated apoptosis. Together, our findings show how the phosphorylation status of pSTAT1 determines its function as a tumor suppressor, with uSTAT1 acting as a tumor promoter that acts by elevating resistance to Fas-mediated apoptosis to promote immune escape.

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