Gene Summary

Gene:IDO1; indoleamine 2,3-dioxygenase 1
Aliases: IDO, INDO, IDO-1
Summary:This gene encodes indoleamine 2,3-dioxygenase (IDO) - a heme enzyme that catalyzes the first and rate-limiting step in tryptophan catabolism to N-formyl-kynurenine. This enzyme acts on multiple tryptophan substrates including D-tryptophan, L-tryptophan, 5-hydroxy-tryptophan, tryptamine, and serotonin. This enzyme is thought to play a role in a variety of pathophysiological processes such as antimicrobial and antitumor defense, neuropathology, immunoregulation, and antioxidant activity. Through its expression in dendritic cells, monocytes, and macrophages this enzyme modulates T-cell behavior by its peri-cellular catabolization of the essential amino acid tryptophan.[provided by RefSeq, Feb 2011]
Databases:OMIM, HGNC, GeneCard, Gene
Protein:indoleamine 2,3-dioxygenase 1
Source:NCBIAccessed: 08 August, 2015


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 08 August 2015 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.

  • Follicular Adenocarcinoma
  • Inflammation
  • Thyroid Cancer
  • Cancer Gene Expression Regulation
  • Viral Proteins
  • Virus Latency
  • Carcinoma, Medullary
  • Neoplastic Cell Transformation
  • Young Adult
  • Genomics
  • Herpesvirus 4, Human
  • U937 Cells
  • Ovarian Cancer
  • T-Lymphocytes, Regulatory
  • Host-Pathogen Interactions
  • Tumor Virus Infections
  • Genetic Variation
  • Interleukin-2 Receptor alpha Subunit
  • HEK293 Cells
  • Estrogen Receptors
  • Cancer RNA
  • Lung Cancer
  • Herpesviridae Infections
  • Gene Expression
  • Forkhead Transcription Factors
  • Chromosome 8
  • Single Nucleotide Polymorphism
  • Western Blotting
  • Epstein-Barr Virus Infections
  • Endometrium
  • Non-Hodgkin Lymphoma
  • Immunotherapy
  • Gene Expression Profiling
  • Virus Replication
  • Angiogenesis
  • Cultured Cells
  • Up-Regulation
  • Stomach Cancer
  • Indoleamine-Pyrrole 2,3,-Dioxygenase
  • Tumor Microenvironment
  • Cell Proliferation
  • 1-methyltryptophan
  • Databases, Nucleic Acid
Tag cloud generated 08 August, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (6)

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: IDO1 (cancer-related)

Yoshii M, Tanaka H, Ohira M, et al.
Regulation of neutrophil infiltration into peritoneal cavity by laparoscopic gastrectomy.
Hepatogastroenterology. 2015 Mar-Apr; 62(138):546-50 [PubMed] Related Publications
BACKGROUND/AIMS: Laparoscopic surgery is a minimally invasive operation developed for treating gastrointestinal malignancies. We aimed to characterize the differences in the intra-abdominal environment following open and laparoscopic surgeries.
METHODOLOGY: We investigated data of 48 patients who underwent gastrectomy between 2010 and 2012. We analyzed the mRNA expression of chemokines, indoleamine 2, 3-dioxygenase (IDO), and so on in peritoneal lavage fluid with real-time RT-PCR. We also determined the leukocyte population and calculated the granulocyte/lymphocyte (G/L) ratio in peritoneal lavage fluid using flow cytometry.
RESULTS: CCL3 mRNA was significantly upregulated, whereas IDO mRNA was significantly downregulated, in the open group compared to the laparoscopic surgery group. Flow cytometry revealed that the G/L ratio was significantly higher in the open group.
CONCLUSIONS: We suggest that the production of chemokines and neutrophil infiltration into the abdominal cavity may be suppressed in the laparoscopic surgery. Thus, laparoscopic surgery may be beneficial in preserving local immunity.

Denkert C, von Minckwitz G, Brase JC, et al.
Tumor-infiltrating lymphocytes and response to neoadjuvant chemotherapy with or without carboplatin in human epidermal growth factor receptor 2-positive and triple-negative primary breast cancers.
J Clin Oncol. 2015; 33(9):983-91 [PubMed] Related Publications
PURPOSE: Modulation of immunologic interactions in cancer tissue is a promising therapeutic strategy. To investigate the immunogenicity of human epidermal growth factor receptor 2 (HER2) -positive and triple-negative (TN) breast cancers (BCs), we evaluated tumor-infiltrating lymphocytes (TILs) and immunologically relevant genes in the neoadjuvant GeparSixto trial.
PATIENTS AND METHODS: GeparSixto investigated the effect of adding carboplatin (Cb) to an anthracycline-plus-taxane combination (PM) on pathologic complete response (pCR). A total of 580 tumors were evaluated before random assignment for stromal TILs and lymphocyte-predominant BC (LPBC). mRNA expression of immune-activating (CXCL9, CCL5, CD8A, CD80, CXCL13, IGKC, CD21) as well as immunosuppressive factors (IDO1, PD-1, PD-L1, CTLA4, FOXP3) was measured in 481 tumors.
RESULTS: Increased levels of stromal TILs predicted pCR in univariable (P < .001) and multivariable analyses (P < .001). pCR rate was 59.9% in LPBC and 33.8% for non-LPBC (P < .001). pCR rates ≥ 75% were observed in patients with LPBC tumors treated with PMCb, with a significant test for interaction with therapy in the complete (P = .002) and HER2-positive (P = .006), but not the TNBC, cohorts. Hierarchic clustering of mRNA markers revealed three immune subtypes with different pCR rates (P < .001). All 12 immune mRNA markers were predictive for increased pCR. The highest odds ratios (ORs) were observed for PD-L1 (OR, 1.57; 95% CI, 1.34 to 1.86; P < .001) and CCL5 (OR, 1.41; 95% CI, 1.23 to 1.62; P < .001).
CONCLUSION: Immunologic factors were highly significant predictors of therapy response in the GeparSixto trial, particularly in patients treated with Cb. After further standardization, they could be included in histopathologic assessment of BC.

Nallapalle SR, Daripally S, Prasad VT
Promoter polymorphism of FASL confers protection against female-specific cancers and those of FAS impact the cancers divergently.
Tumour Biol. 2015; 36(4):2709-24 [PubMed] Related Publications
We investigated risk association of FAS (-1377 G>A and -670 A>G) and FASL (-844 T>C) promoter polymorphisms with breast, ovarian, cervical, and endometrial cancers and report that the FASL -844 CC genotype was protective against breast, ovarian, cervical, and endometrial cancers (P ≤ 0.01). On the other hand, FAS -1377 GA and AA variants increased risk of breast cancer. However, the GA variant of FAS -1377 was also found to be a risk factor for cervical cancer. In contrast, FAS -670 AG variant significantly lowered risk of breast cancer. Further, we also observed that risk association of co-occurrence of FAS and/or FASL variants with the cancers varied as compared to the presence of individual polymorphisms. Although risk and protective haplotypes of FAS SNPs were observed across the cancer phenotypes, the association of the haplotypes was significant for breast cancer alone with a 3-fold enhanced risk. The protective effect of the FASL CC genotype seen in this study suggests that similar biomolecular mechanisms involving FASL might play a role in female-specific cancers.

Adams S, Teo C, McDonald KL, et al.
Involvement of the kynurenine pathway in human glioma pathophysiology.
PLoS One. 2014; 9(11):e112945 [PubMed] Free Access to Full Article Related Publications
The kynurenine pathway (KP) is the principal route of L-tryptophan (TRP) catabolism leading to the production of kynurenine (KYN), the neuroprotectants, kynurenic acid (KYNA) and picolinic acid (PIC), the excitotoxin, quinolinic acid (QUIN) and the essential pyridine nucleotide, nicotinamide adenine dinucleotide (NAD(+)). The enzymes indoleamine 2,3-dioxygenase-1 (IDO-1), indoleamine 2,3-dioxygenase-2 (IDO-2) and tryptophan 2,3-dioxygenase (TDO-2) initiate the first step of the KP. IDO-1 and TDO-2 induction in tumors are crucial mechanisms implicated to play pivotal roles in suppressing anti-tumor immunity. Here, we report the first comprehensive characterisation of the KP in 1) cultured human glioma cells and 2) plasma from patients with glioblastoma (GBM). Our data revealed that interferon-gamma (IFN-γ) stimulation significantly potentiated the expression of the KP enzymes, IDO-1 IDO-2, kynureninase (KYNU), kynurenine hydroxylase (KMO) and significantly down-regulated 2-amino-3-carboxymuconate semialdehyde decarboxylase (ACMSD) and kynurenine aminotransferase-I (KAT-I) expression in cultured human glioma cells. This significantly increased KP activity but significantly lowered the KYNA/KYN neuroprotective ratio in human cultured glioma cells. KP activation (KYN/TRP) was significantly higher, whereas the concentrations of the neuroreactive KP metabolites TRP, KYNA, QUIN and PIC and the KYNA/KYN ratio were significantly lower in GBM patient plasma (n = 18) compared to controls. These results provide further evidence for the involvement of the KP in glioma pathophysiology and highlight a potential role of KP products as novel and highly attractive therapeutic targets to evaluate for the treatment of brain tumors, aimed at restoring anti-tumor immunity and reducing the capacity for malignant cells to produce NAD(+), which is necessary for energy production and DNA repair.

Sioud M, Mobergslien A, Sæbøe-Larssen S
Immunosuppressive factor blockade in dendritic cells via siRNAs results in objective clinical responses.
Methods Mol Biol. 2015; 1218:269-76 [PubMed] Related Publications
Over the past decade, immunotherapy has emerged as a promising new form of cancer treatment with the potential to eradicate tumor metastasis. However, its curative potential is in general limited by the existence of negative feedback mechanisms that control dendritic cells (DCs) and T-cell activation. For clinically effective immunity, there is a need of inhibiting the expression of these immune suppressors. This could enhance the activation of DCs, T cells, and natural killer cells, and might be beneficial for cancer immunotherapy. Among the immune inhibitory molecules expressed by DCs is indoleamine 2,3-dioxygenase (IDO), an enzyme that conveys immunosuppressive effects by degrading tryptophan, an essential amino acid required for T-cell proliferation and survival. Depletion of tryptophan by IDO-positive DCs induces T-cell apoptosis and the conversion of naïve CD4+ T cells into regulatory T cells that further suppress antitumor immunity. Herein, we describe a protocol for in vitro synthesis of small interfering RNA against IDO and other immunosuppressive factors such as interleukin-10 and programmed cell death-1 ligands in order to reverse immune suppression mediated by DCs. Vaccination with IDO-silenced DC vaccines enhanced immune responses and antitumor immunity in cancer patients.

Jacca S, Franceschi V, Agosti M, et al.
Interferon gamma-mediated BoHV-4 replication restriction in bovine endometrial stromal cells is host IDO1 gene expression independent and BoHV-4 IE2 gene expression dependent.
Biol Reprod. 2014; 91(5):112 [PubMed] Related Publications
In the present work the interaction between bovine herpesvirus 4 (BoHV-4)-infected bovine endometrial stromal cells (BESCs) and interferon gamma (IFNG) was investigated. Starting from the particular tropism of BoHV-4 toward BESCs, a pure population of these cells, free of CD45-positive cells, was prepared and proven to have a bona fide mesenchymal derivation as shown by vimentin-positive and cytokeratin-negative staining. BESCs expressed functional IFNG receptors (IFNGR) 1 and 2 but not IFNG ligand. BESCs transfected with a new reporter construct made by cloning the bovine indoleamine 2, 3-dioxygenase 1 (IDO1) promoter in front of the luciferase reporter gene responded to exogenous IFNG treatment. Further, IFNG-treated or constitutively secreting IFNG BESCs strongly restricted BoHV-4 replication and consequent cytopathic effect. IDO1 expression in BESCs was tightly induced by IFNG and IDO1 was previously shown to be the mediator for some of the IFNG pathogenostatic effects. However, IDO1 inhibitors and IDO1 constitutive expression could not respectively abrogate or recapitulate IFNG effect on BoHV-4-infected BESCs, whereas BoHV-4 immediate early (IE2) gene expression was transcriptionally depressed by IFNG axis activation independently from IDO1 expression; this was further confirmed by revealing a BoHV-4 IE2 gene promoter area containing potential responsive elements interacting with inhibitory transcription factors induced by IFNG in BESCs. The data achieved in this work highlight at least two issues: first, the role of BESCs as target/effector cells for the IFNG; second, the importance of uterine IFNG integrity to control BoHV-4 infection recrudescence from a persistent/latent state to a chronic disease, endometritis.

Bi WW, Zhang WH, Yin GH, et al.
Analysis of indoleamine 2-3 dioxygenase (IDO) and EGFR co-expression in breast cancer tissue by immunohistochemistry.
Asian Pac J Cancer Prev. 2014; 15(14):5535-8 [PubMed] Related Publications
BACKGROUND: To determine the amount of co-expression of IDO and EGFR in breast cancer patients.
MATERIALS AND METHODS: In order to obtain the distribution of co-expression of IDO and EGFR in breast cancer, we tested 110 breast cancer paraffin tissue blocks with immunohistochemical methods. Then we investigated the relationship between the diagnostic and pathologic characteristics (tumor size, lymph node status, histologic grade, the gene expression of ER, PR, HER2, p53, Ki67 and PCNA) with the situation of co-expression of IDO and EGFR by reviewing the medical records of 32 breast cancer patients.
RESULTS: Among 110 breast cancers, 32 cases demonstrated IDO and EGFR co-expression (29.1%), IDO and EGFR synchronous co-expression being found in 19.1% and asynchronous in 10.0%.
CONCLUSIONS: IDO and EGFR were co-expressed in breast cancer, including synchronous and asynchronous co-expression. The results suggest that considering IDO and EGFR as two indicators for breast cancer treatment or prognosis analysis provides a potential option of individual treatment for the portion of breast cancer patients with co-expression of IDO and EGFR.

Yu J, Wang Y, Yan F, et al.
Noncanonical NF-κB activation mediates STAT3-stimulated IDO upregulation in myeloid-derived suppressor cells in breast cancer.
J Immunol. 2014; 193(5):2574-86 [PubMed] Related Publications
Immunotherapy for cancer treatment is achieved through the activation of competent immune effector cells and the inhibition of immunosuppressive cells, such as myeloid-derived suppressor cells (MDSCs). Although MDSCs have been shown to contribute to breast cancer development, the mechanism underlying MDSC-mediated immunosuppression is unclear. We have identified a poorly differentiated MDSC subset in breast cancer-suppressing T cell function through STAT3-dependent IDO upregulation. In this study we investigated the mechanisms underlying aberrant expression of IDO in MDSCs. MDSCs were induced by coculturing human CD33(+) myeloid progenitors with MDA-MB-231 breast cancer cells. Increased STAT3 activation in MDSCs was correlated with activation of the noncanonical NF-κB pathway, including increased NF-κB-inducing kinase (NIK) protein level, phosphorylation of cytoplasmic inhibitor of NF-κB kinase α and p100, and RelB-p52 nuclear translocation. Blocking STAT3 activation with the small molecule inhibitor JSI-124 significantly inhibited the accumulation of NIK and IDO expression in MDSCs. Knockdown of NIK in MDSCs suppressed IDO expression but not STAT3 activation. RelB-p52 dimers were found to directly bind to the IDO promoter, leading to IDO expression in MDSCs. IL-6 was found to stimulate STAT3-dependent, NF-κB-mediated IDO upregulation in MDSCs. Furthermore, significant positive correlation between the numbers of pSTAT3(+) MDSCs, IDO(+) MDSCs, and NIK(+) MDSCs was observed in human breast cancers. These results demonstrate a STAT3/NF-κB/IDO pathway in breast cancer-derived MDSCs, which provides insight into understanding immunosuppressive mechanisms of MDSCs in breast cancer.

Chen JY, Li CF, Kuo CC, et al.
Cancer/stroma interplay via cyclooxygenase-2 and indoleamine 2,3-dioxygenase promotes breast cancer progression.
Breast Cancer Res. 2014; 16(4):410 [PubMed] Free Access to Full Article Related Publications
INTRODUCTION: Expression of indoleamine 2,3-dioxygenase (IDO) in primary breast cancer increases tumor growth and metastasis. However, the clinical significance of stromal IDO and the regulation of stromal IDO are unclear.
METHODS: Metabolomics and enzyme-linked immunosorbent assay (ELISA) were used to study the effect of cyclooxygenase-2 (COX-2)-overexpressing breast cancer cells on IDO expression in co-cultured human breast fibroblasts. Biochemical inhibitors and short-hairpin RNA (shRNA) were used to clarify how prostaglandin E2 (PGE2) upregulates IDO expression. Associations of stromal IDO with clinicopathologic parameters were tested in tumor specimens. An orthotopic animal model was used to examine the effect of COX-2 and IDO inhibitors on tumor growth.
RESULTS: Kynurenine, the metabolite generated by IDO, increases in the supernatant of fibroblasts co-cultured with COX-2-overexpressing breast cancer cells. PGE2 released by cancer cells upregulates IDO expression in fibroblasts through an EP4/signal transducer and activator of transcription 3 (STAT3)-dependent pathway. Conversely, fibroblast-secreted kynurenine promotes the formation of the E-cadherin/Aryl hydrocarbon receptor (AhR)/S-phase kinase-associated protein 2 (Skp2) complex, resulting in degradation of E-cadherin to increase breast cancer invasiveness. The enhancement of motility of breast cancer cells induced by co-culture with fibroblasts is suppressed by the IDO inhibitor 1-methyl-tryptophan. Pathological analysis demonstrates that upregulation of stromal IDO is a poor prognosis factor and is associated with of COX-2 overexpression. Co-expression of cancer COX-2 and stromal IDO predicts a worse disease-free and metastasis-free survival. Finally, COX-2 and IDO inhibitors inhibit tumor growth in vivo.
CONCLUSION: Integration of metabolomics and molecular and pathological approaches reveals the interplay between cancer and stroma via COX-2, and IDO promotes tumor progression and predicts poor patient survival.

Jitschin R, Braun M, Büttner M, et al.
CLL-cells induce IDOhi CD14+HLA-DRlo myeloid-derived suppressor cells that inhibit T-cell responses and promote TRegs.
Blood. 2014; 124(5):750-60 [PubMed] Related Publications
Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population that shares certain characteristics including an aberrant myeloid phenotype and the ability to suppress T cells. MDSCs have been predominantly studied in malignant diseases and findings suggest involvement in tumor-associated immune suppression. Chronic lymphocytic leukemia (CLL) is the leukemia with the highest incidence among adults. Immune defects occur already at early disease stages and impact the clinical course. We assessed presence, frequency, association to other immune parameters, and functional properties of circulating CD14(+) cells lacking HLA-DR expression (HLA-DR(lo)) in patients with untreated CLL. These monocytic cells represent one of the best-defined human MDSC subsets. Frequency of CD14(+)HLA-DR(lo) cells was significantly increased in CLL patients. Furthermore, MDSCs suppressed in vitro T-cell activation and induced suppressive regulatory T cells (TRegs). The MDSC-mediated modulation of T cells could be attributed to their increased indoleamine 2,3-dioxygenase (IDO) activity. CLL cells induced IDO(hi) MDSCs from healthy donor monocytes suggesting bidirectional crosstalk between CLL-cells, MDSCs, and TRegs. Overall, we identified a MDSC population that expands in CLL. The exact mechanisms responsible for such accumulation remain to be elucidated and it will be of interest to test whether antagonizing suppressive functions of CLL MDSCs could represent a mean for enhancing immune responses.

Jin P, Civini S, Zhao Y, et al.
Direct T cell-tumour interaction triggers TH1 phenotype activation through the modification of the mesenchymal stromal cells transcriptional programme.
Br J Cancer. 2014; 110(12):2955-64 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Mesenchymal stromal cells (MSCs) are heterogeneous cells with immunoregulatory and wound-healing properties. In cancer, they are known to be an essential part of the tumour microenvironment. However, their role in tumour growth and rejection remains unclear. To investigate this, we co-cultured human MSCs, tumour infiltrating lymphocytes (TIL), and melanoma cells to investigate the role of MSCs in the tumour environment.
METHODS: Mesenchymal stromal cells were co-cultured with melanoma antigen-specific TIL that were stimulated either with HLA-A*0201(+) melanoma cells or with a corresponding clone that had lost HLA-A*0201 expression.
RESULTS: Activated TIL induced profound pro-inflammatory gene expression signature in MSCs. Analysis of culture supernatant found that MSCs secreted pro-inflammatory cytokines, including TH1 cytokines that have been previously associated with immune-mediated antitumor responses. In addition, immunohistochemical analysis on selected markers revealed that the same activated MSCs secreted both the TH1 cytokine (interleukin-12) and indoleamine 2,3 dioxygenase (IDO), a classical immunosuppressive factor.
CONCLUSIONS: This study reflected that the plasticity of MSCs is highly dependent upon microenvironment conditions. Tumour-activated TIL induced TH1 phenotype change in MSCs that is qualitatively similar to the previously described immunologic constant of rejection signature observed during immune-mediated, tissue-specific destruction. This response may be responsible for the in loco amplification of antigen-specific anti-cancer immune response.

Charbonneau B, Moysich KB, Kalli KR, et al.
Large-scale evaluation of common variation in regulatory T cell-related genes and ovarian cancer outcome.
Cancer Immunol Res. 2014; 2(4):332-40 [PubMed] Free Access to Full Article Related Publications
The presence of regulatory T cells (Treg) in solid tumors is known to play a role in patient survival in ovarian cancer and other malignancies. We assessed inherited genetic variations via 749 tag single-nucleotide polymorphisms (SNP) in 25 Treg-associated genes (CD28, CTLA4, FOXP3, IDO1, IL10, IL10RA, IL15, 1L17RA, IL23A, IL23R, IL2RA, IL6, IL6R, IL8, LGALS1, LGALS9, MAP3K8, STAT5A, STAT5B, TGFB1, TGFB2, TGFB3, TGFBR1, TGRBR2, and TGFBR3) in relation to ovarian cancer survival. We analyzed genotype and overall survival in 10,084 women with invasive epithelial ovarian cancer, including 5,248 high-grade serous, 1,452 endometrioid, 795 clear cell, and 661 mucinous carcinoma cases of European descent across 28 studies from the Ovarian Cancer Association Consortium (OCAC). The strongest associations were found for endometrioid carcinoma and IL2RA SNPs rs11256497 [HR, 1.42; 95% confidence interval (CI), 1.22-1.64; P = 5.7 × 10(-6)], rs791587 (HR, 1.36; 95% CI, 1.17-1.57; P = 6.2 × 10(-5)), rs2476491 (HR, = 1.40; 95% CI, 1.19-1.64; P = 5.6 × 10(-5)), and rs10795763 (HR, 1.35; 95% CI, 1.17-1.57; P = 7.9 × 10(-5)), and for clear cell carcinoma and CTLA4 SNP rs231775 (HR, 0.67; 95% CI, 0.54-0.82; P = 9.3 × 10(-5)) after adjustment for age, study site, population stratification, stage, grade, and oral contraceptive use. The rs231775 allele associated with improved survival in our study also results in an amino acid change in CTLA4 and previously has been reported to be associated with autoimmune conditions. Thus, we found evidence that SNPs in genes related to Tregs seem to play a role in ovarian cancer survival, particularly in patients with clear cell and endometrioid epithelial ovarian cancer.

Gundimeda SD, Ahmed F, Mundada MC, et al.
A near tetraploid clone in acute myeloid leukemia with CD56 expression.
J Cancer Res Ther. 2014 Jan-Mar; 10(1):187-90 [PubMed] Related Publications
Acute myeloid leukemia (AML) is a heterogeneous disorder characterized by specific morphology, immunophenotype and genetic rearrangements. Multiple recurrent chromosomal aberrations have been identified by conventional cytogenetic analysis, which are now widely recognized as one of the most important diagnostic and prognostic determinants in AML. Here, we present a case with unusual cytogenetics, which has been described in very few patients.

Isla Larrain MT, Rabassa ME, Lacunza E, et al.
IDO is highly expressed in breast cancer and breast cancer-derived circulating microvesicles and associated to aggressive types of tumors by in silico analysis.
Tumour Biol. 2014; 35(7):6511-9 [PubMed] Related Publications
Indoleamine-2,3-dioxygenase (IDO) has been established as a normal mechanism of peripheral tolerance and immunosuppression. Besides, malignant tumors release microvesicles (MV) related with tumor dissemination. The aims of this study were to determine the expression of IDO in breast cancer and circulating microvesicles from breast cancer patients and to perform an in silico analysis to find genes co-expressed to IDO. One hundred and twenty-two tissue and serum breast samples (91 malignant, 21 benign, and 10 normal), and MCF7, MDA-MB-231, and T47D breast cancer cell lines were included. Standard immunohistochemistry (IHC), immunocytochemistry (ICC), Western blot (WB), and RT-PCR were employed. Microvesicle isolation from plasma samples was obtained by serial centrifugation and ultracentrifugation. By IHC, 60 % breast cancer, 43 % benign, and 20 % normal samples were positive. Significant differences were found among normal, benign, and malignant samples. Breast cancer stages I, II, and III expressed IDO in 42, 66, and 71 % of samples, respectively, while breast cancer cell lines also reacted; by WB, 9/25 microvesicles fractions showed bands at 42 kD. In silico analysis of IDO 1 gene expression in breast cancer showed its association with several genes related to immune response and apoptosis. Moreover, IDO and co-expressed genes were found predominately in basal and erbB2 subtypes. The cumulative data indicate a high expression of IDO in breast cancer which increased with higher stages. Furthermore, IDO was found in association with circulating breast cancer MV, while experimental and in silico gene expression revealed that IDO was mainly expressed in a triple-negative subgroup.

Litzenburger UM, Opitz CA, Sahm F, et al.
Constitutive IDO expression in human cancer is sustained by an autocrine signaling loop involving IL-6, STAT3 and the AHR.
Oncotarget. 2014; 5(4):1038-51 [PubMed] Free Access to Full Article Related Publications
Indoleamine-2,3-dioxygenase (IDO) inhibitors have entered clinical trials based on their ability to restore anti-tumor immunity in preclinical studies. However, the mechanisms leading to constitutive expression of IDO in human tumors are largely unknown. Here we analyzed the pathways mediating constitutive IDO expression in human cancer. IDO-positive tumor cells and tissues showed basal phosphorylation and acetylation of STAT3 as evidenced by western blotting and immunoprecipitation. Inhibition of IL-6 or STAT3 using siRNA and/or pharmacological inhibitors reduced IDO mRNA and protein expression as well as kynurenine formation. In turn, IDO enzymatic activity activated the AHR as shown by the induction of AHR target genes. IDO-mediated AHR activation induced IL-6 expression, while inhibition or knockdown of the AHR reduced IL-6 expression. IDO activity thus sustains its own expression via an autocrine AHR-IL-6-STAT3 signaling loop. Inhibition of the AHR-IL-6-STAT3 signaling loop restored T-cell proliferation in mixed leukocyte reactions performed in the presence of IDO-expressing human cancer cells. Identification of the IDO-AHR-IL-6-STAT3 signaling loop maintaining IDO expression in human cancers reveals novel therapeutic targets for the inhibition of this core pathway promoting immunosuppression of human cancers. The relevance of the IDO-AHR-IL-6-STAT3 transcriptional circuit is underscored by the finding that high expression of its members IDO, STAT3 and the AHR target gene CYP1B1 is associated with reduced relapse-free survival in lung cancer patients.

Mandegary A, Torshabi M, Seyedabadi M, et al.
Indomethacin-enhanced anticancer effect of arsenic trioxide in A549 cell line: involvement of apoptosis and phospho-ERK and p38 MAPK pathways.
Biomed Res Int. 2013; 2013:237543 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Focusing on novel drug combinations that target different pathways especially apoptosis and MAPK could be a rationale for combination therapy in successful treatment of lung cancer. Concurrent use of cyclooxygenase (COX) inhibitors with arsenic trioxide (ATO) might be a possible treatment option.
METHODS: Cytotoxicity of ATO, dexamethasone (Dex), celecoxib (Cel), and Indomethacin (Indo) individually or in combination was determined at 24, 48, and 72 hrs in A549 lung cancer cells. The COX-2 gene and protein expression, MAPK pathway proteins, and caspase-3 activity were studied for the most cytotoxic combinations.
RESULTS: The IC50s of ATO and Indo were 68.7 μmol/L and 396.5 μmol/L, respectively. Treatment of cells with combinations of clinically relevant concentrations of ATO and Indo resulted in greater growth inhibition and apoptosis induction than did either agent alone. Caspase-3 activity was considerably high in the presence of ATO and Indo but showed no difference in single or combination use. Phosphorylation of p38 and ERK1/2 was remarkable in the concurrent presence of both drugs.
CONCLUSIONS: Combination therapy with ATO and Indo exerted a very potent in vitro cytotoxic effect against A549 lung cancer cells. Activation of ERK and p38 pathways might be the mechanism of higher cytotoxic effect of ATO-Indo combination.

Trivanović D, Nikolić S, Krstić J, et al.
Characteristics of human adipose mesenchymal stem cells isolated from healthy and cancer affected people and their interactions with human breast cancer cell line MCF-7 in vitro.
Cell Biol Int. 2014; 38(2):254-65 [PubMed] Related Publications
Adipose tissue is an attractive source of mesenchymal stem/stromal cells (MSCs) with potential applications in reconstructive plastic surgery and regenerative medicine. The aim of this study was to characterise human adipose tissue MSCs (ASCs) derived from healthy individuals and cancer patients and to compare their interactions with tumour cells. ASCs were isolated from adipose tissue of healthy donors, breast cancer-adjacent adipose tissue of breast cancer patients and tumour-adjacent adipose tissue of non-breast cancer patients. Their proliferation, differentiation, immunophenotype and gene expression were assessed and effects on the proliferation of human breast cancer cell line MCF-7 compared. ASCs from all sources exhibited similar morphology, proliferative and differentiation potential, showing the characteristic pattern of mesenchymal surface markers expression (CD90, CD105, CD44H, CD73) and the lack of HLA-DR and hematopoietic markers (CD11a, CD33, CD45, Glycophorin-CD235a), but uneven expression of CD34. ASCs also shared a common positive gene expression of HLA-DR, HLA-A, IL-6, TGF-β and HIF-1, but were negative for HLA-G, while the expression levels of Cox-2 and IDO-1 varied. All ASCs significantly stimulated the proliferation of MCF-7 tumour cells in direct mixed co-cultures and transwell system, although their conditioned media displayed antiproliferative activity. Data obtained showed that ASCs with similar characteristics are easily isolated from various donors and sites of origin, although ASCs could both suppress and favour tumour cells growth, emphasising the importance of cellular context within the microenvironment and pointing to the significance of safety studies to exclude any potential clinical risk of their application in regenerative medicine.

Pooja S, Francis A, Rajender S, et al.
Strong impact of TGF-β1 gene polymorphisms on breast cancer risk in Indian women: a case-control and population-based study.
PLoS One. 2013; 8(10):e75979 [PubMed] Free Access to Full Article Related Publications
INTRODUCTION: TGF-β1 is a multi-functional cytokine that plays an important role in breast carcinogenesis. Critical role of TGF-β1 signaling in breast cancer progression is well documented. Some TGF-β1 polymorphisms influence its expression; however, their impact on breast cancer risk is not clear.
METHODS: We analyzed 1222 samples in a candidate gene-based genetic association study on two distantly located and ethnically divergent case-control groups of Indian women, followed by a population-based genetic epidemiology study analyzing these polymorphisms in other Indian populations. The c.29C>T (Pro10Leu, rs1982073 or rs1800470) and c.74G>C (Arg25Pro, rs1800471) polymorphisms in the TGF-β1 gene were analyzed using direct DNA sequencing, and peripheral level of TGF-β1 were measured by ELISA.
RESULTS: c.29C>T substitution increased breast cancer risk, irrespective of ethnicity and menopausal status. On the other hand, c.74G>C substitution reduced breast cancer risk significantly in the north Indian group (p = 0.0005) and only in the pre-menopausal women. The protective effect of c.74G>C polymorphism may be ethnicity-specific, as no association was seen in south Indian group. The polymorphic status of c.29C>T was comparable among Indo-Europeans, Dravidians, and Tibeto-Burmans. Interestingly, we found that Tibeto-Burmans lack polymorphism at c.74G>C locus as true for the Chinese populations. However, the Brahmins of Nepal (Indo-Europeans) showed polymorphism in 2.08% of alleles. Mean TGF-β1 was significantly elevated in patients in comparison to controls (p<0.001).
CONCLUSION: c.29C>T and c.74G>C polymorphisms in the TGF-β1 gene significantly affect breast cancer risk, which correlates with elevated TGF-β1 level in the patients. The c.29C>T locus is polymorphic across ethnically different populations, but c.74G>C locus is monomorphic in Tibeto-Burmans and polymorphic in other Indian populations.

Duechler M, Peczek L, Zuk K, et al.
The heterogeneous immune microenvironment in breast cancer is affected by hypoxia-related genes.
Immunobiology. 2014; 219(2):158-65 [PubMed] Related Publications
The immune system constitutes an important first-line defence against malignant transformation. However, cancer mediated immunosuppression inactivates the mechanisms of host immune surveillance. Cancer cells shut down anti-cancer immunity through direct cell-cell interactions with leukocytes and through soluble factors, establishing an immunosuppressive environment for unimpeded cancer growth. The composition of the immunosuppressive microenvironment in breast tumours is not well documented. To address this question, selected immunosuppressive factors were analyzed in tumour specimens from 33 breast cancer patients after surgery. The mRNA expression of selected genes was quantified in fresh tumour samples. Tumour infiltrating leukocytes were characterized by flow cytometry to identify regulatory T cells, myeloid derived suppressor cells, and type 2 macrophages. Statistical analysis revealed several interesting correlations between the studied parameters and clinical features. Overall, a surprisingly high degree of heterogeneity in the composition of the immunosuppressive environment was found across all breast cancer samples which adds to the complexity of this disease. The influence of the hypoxia inducible factors (HIFs) on the immune microenvironment was also addressed. The level of HIFs correlated with hormone receptor status and the expression of several immunosuppressive molecules. Targeting HIFs might not only sensitize breast tumours for radiation and chemotherapies but also interfere with cancer immunosuppression.

Iachininoto MG, Nuzzolo ER, Bonanno G, et al.
Cyclooxygenase-2 (COX-2) inhibition constrains indoleamine 2,3-dioxygenase 1 (IDO1) activity in acute myeloid leukaemia cells.
Molecules. 2013; 18(9):10132-45 [PubMed] Related Publications
Indoleamine 2,3-dioxygenase 1 (IDO1) metabolizes L-tryptophan to kynurenines (KYN), inducing T-cell suppression either directly or by altering antigen-presenting-cell function. Cyclooxygenase (COX)-2, the rate-limiting enzyme in the synthesis of prostaglandins, is over-expressed by several tumours. We aimed at determining whether COX-2 inhibitors down-regulate the IFN-g-induced expression of IDO1 in acute myeloid leukaemia (AML) cells. IFN-γ at 100 ng/mL up-regulated COX-2 and IDO1 in HL-60 AML cells, both at mRNA and protein level. The increased COX-2 and IDO1 expression correlated with heightened production of prostaglandin (PG)E₂ and kynurenines, respectively. Nimesulide, a preferential COX-2 inhibitor, down-regulated IDO1 mRNA/protein and attenuated kynurenine synthesis, suggesting that overall IDO inhibition resulted both from reduced IDO1 gene transcription and from inhibited IDO1 catalytic activity. From a functional standpoint, IFN-g-challenged HL-60 cells promoted the in vitro conversion of allogeneic CD4⁺CD25⁻ T cells into bona fide CD4⁺CD25⁺FoxP3⁺ regulatory T cells, an effect that was significantly reduced by treatment of IFN-γ-activated HL-60 cells with nimesulide. Overall, these data point to COX-2 inhibition as a potential strategy to be pursued with the aim at circumventing leukaemia-induced, IDO-mediated immune dysfunction.

He YW, Wang HS, Zeng J, et al.
Sodium butyrate inhibits interferon-gamma induced indoleamine 2,3-dioxygenase expression via STAT1 in nasopharyngeal carcinoma cells.
Life Sci. 2013; 93(15):509-15 [PubMed] Related Publications
AIMS: Indoleamine 2,3-dioxygenase (IDO) inhibits T-cell proliferation by catalyzing the conversion of l-tryptophan to l-kynurenine. IDO-induced immune tolerance weakens the clinical outcomes of immunotherapies. Sodium butyrate (NaB), one of the histone deacetylase inhibitors (HDACIs), has potential anti-tumor effects. Our previous studies revealed that NaB could inhibit IFN-γ induced IDO expression in nasopharyngeal carcinoma cells, CNE2. In the present study, we aim to investigate to the mechanism of NaB interfering with the interferon-gamma (IFN-γ)-mediated IDO expression signaling transduction.
MAIN METHODS: IDO expression and STAT1 phosphorylation in CNE2 cells were analyzed by western blotting and STAT1 acetylation was evaluated by immunoprecipitation. STAT1 nuclear translocation and NF-κB activity were detected by transient transfection and reporter gene assay.
KEY FINDINGS: We found that NaB inhibited IFN-γ-induced IDO expression in CNE2 cells via decreasing phosphorylation and nuclear translocation of STAT1, but not via down-regulation of IFN-γ-receptor (IFNGR). Immunoprecipitation assays revealed that NaB increased STAT1 acetylation. Furthermore, NaB elevated the activity of NF-κB in CNE2 cells, and blocking the NF-κB activity had no effect on the IFN-γ-induced IDO expression.
SIGNIFICANCE: These results suggest that NaB inhibited IFN-γ-induced IDO expression via STAT1 increased acetylation, decreased phosphorylation, and reduced nuclear translocation. These provided new evidence for the anti-tumor action of NaB and potential drug targets to reduce the IDO-induced immune tolerance.

Zhang H, Maric I, DiPrima MJ, et al.
Fibrocytes represent a novel MDSC subset circulating in patients with metastatic cancer.
Blood. 2013; 122(7):1105-13 [PubMed] Free Access to Full Article Related Publications
Fibrocytes are hematopoietic stem cell-derived fibroblast precursors that are implicated in chronic inflammation, fibrosis, and wound healing. Myeloid-derived suppressor cells (MDSCs) expand in cancer-bearing hosts and contribute to tumor immune evasion. They are typically described as CD11b⁺HLA-DR⁻ in humans. We report abnormal expansions of CD11b⁺HLA-DR⁺ myeloid cells in peripheral blood mononuclear fractions of subjects with metastatic pediatric sarcomas. Like classical fibrocytes, they display cell surface α smooth muscle actin, collagen I/V, and mediate angiogenesis. However, classical fibrocytes serve as antigen presenters and augment immune reactivity, whereas fibrocytes from cancer subjects suppressed anti-CD3-mediated T-cell proliferation, primarily via indoleamine oxidase (IDO). The degree of fibrocyte expansion observed in individual subjects directly correlated with the frequency of circulating GATA3⁺CD4⁺ cells (R = 0.80) and monocytes from healthy donors cultured with IL-4 differentiated into fibrocytes with the same phenotypic profile and immunosuppressive properties as those observed in patients with cancer. We thus describe a novel subset of cancer-induced myeloid-derived suppressor cells, which bear the phenotypic and functional hallmarks of fibrocytes but mediate immune suppression. These cells are likely expanded in response to Th2 immune deviation and may contribute to tumor progression via both immune evasion and angiogenesis.

Liu XQ, Lu K, Feng LL, et al.
Up-regulated expression of indoleamine 2,3-dioxygenase 1 in non-Hodgkin lymphoma correlates with increased regulatory T-cell infiltration.
Leuk Lymphoma. 2014; 55(2):405-14 [PubMed] Related Publications
Indoleamine 2,3-dioxygenase 1 (IDO1), which is a key enzyme in tryptophan metabolism expressed in some subsets of normal and neoplastic cells, participates in tumor-induced tolerance. However, the mechanisms involved are not clearly understood. A hypothesis suggests that IDO1 may be involved in proliferation and conversion of regulatory T cells (Tregs). In this study, we evaluated the levels of IDO1 and forkhead box P3 (FoxP3) in non-Hodgkin lymphoma (NHL) tissues and performed ex vivo experiments to investigate the role of IDO1 on T-cell tolerance in NHL. The results showed that expressions of IDO1 mRNA and protein were coincidentally higher in NHL tissues than in reactive hyperplasia of lymph node tissues. Up-regulation of IDO1 was correlated with later clinical phases, larger tumors and higher serum lactate dehydrogenase (LDH), and indicated a worse prognosis. FoxP3 mRNA and protein levels were markedly increased alongside elevated IDO1 levels. Co-culture of murine CD4 + CD25- T cells with A20 cells could initiate the conversion of CD4 + CD25+ T cells, which showed a suppressive function in the mixed lymphocyte reaction. Moreover, the potent inhibitor of IDO1, 1-methyl-l-tryptophan, attenuated the conversion of CD4 + CD25- T cells into CD4 + CD25+ FoxP3 + T cells. The results suggested that up-regulation of IDO1 in NHL tissues could induce local immune tolerance by favoring development and infiltration of FoxP3 + Tregs through the conversion of CD4 + CD25- T cells into CD4 + CD25+ FoxP3 + T cells in the tumor microenvironment. This could be a novel mechanism of NHL escape from immune control.

Yen MC, Weng TY, Chen YL, et al.
An HDAC inhibitor enhances cancer therapeutic efficiency of RNA polymerase III promoter-driven IDO shRNA.
Cancer Gene Ther. 2013; 20(6):351-7 [PubMed] Related Publications
Histone deacetylase (HDAC) inhibitors are used in treating certain human malignancies. Our laboratories demonstrated their capability in enhancing antitumor effect of DNA vaccine driven by an RNA polymerase II (RNA pol II) promoter. However, it is unknown whether HDAC inhibitors enhance the therapeutic short hairpin RNA (shRNA) expressed by an RNA polymerase III (RNA pol III) promoter. We investigated whether HDAC inhibitors augmented antitumor effect of indoleamine 2,3 dioxygenase (IDO) shRNA. HDAC inhibitor OSU-HDAC42 and suberoylanilide hydroxamic acid enhanced RNA pol III-driven U6 and H1 promoter activity in three different cell types in vitro: 293, NIH3T3 and dendritic cell line DC2.4. Subcutaneous injection of OSU-HDAC42 enhanced U6 and H1 promoter activity on abdominal skin of mice in vivo. Combination of IDO shRNA and OSU-HDAC42 increased antitumor effect of IDO shRNA in MBT-2 murine bladder tumor model. IDO shRNA induced tumor-infiltrating CD8⁺ and CD4⁺ T cells, whereas OSU-HDAC42 treatment induced tumor-infiltrating CD4⁺ T cells. Combination of OSU-HDAC42 and IDO shRNA further induced tumor-infiltrating natural killer cells and enhanced interferon-γ in lymphocytes, but suppressed interleukin (IL)-4 expression of lymphocytes. In addition, OSU-HDAC42 treatment did not alter mRNA expression of IL-12 and tumor necrosis factor-α. In conclusion, HDAC inhibitor OSU-HDAC42 may serve as adjuvant of the therapeutic shRNA expressed by an RNA pol III promoter.

Strong MJ, Xu G, Coco J, et al.
Differences in gastric carcinoma microenvironment stratify according to EBV infection intensity: implications for possible immune adjuvant therapy.
PLoS Pathog. 2013; 9(5):e1003341 [PubMed] Free Access to Full Article Related Publications
Epstein-Barr virus (EBV) is associated with roughly 10% of gastric carcinomas worldwide (EBVaGC). Although previous investigations provide a strong link between EBV and gastric carcinomas, these studies were performed using selected EBV gene probes. Using a cohort of gastric carcinoma RNA-seq data sets from The Cancer Genome Atlas (TCGA), we performed a quantitative and global assessment of EBV gene expression in gastric carcinomas and assessed EBV associated cellular pathway alterations. EBV transcripts were detected in 17% of samples but these samples varied significantly in EBV coverage depth. In four samples with the highest EBV coverage (hiEBVaGC - high EBV associated gastric carcinoma), transcripts from the BamHI A region comprised the majority of EBV reads. Expression of LMP2, and to a lesser extent, LMP1 were also observed as was evidence of abortive lytic replication. Analysis of cellular gene expression indicated significant immune cell infiltration and a predominant IFNG response in samples expressing high levels of EBV transcripts relative to samples expressing low or no EBV transcripts. Despite the apparent immune cell infiltration, high levels of the cytotoxic T-cell (CTL) and natural killer (NK) cell inhibitor, IDO1, was observed in the hiEBVaGCs samples suggesting an active tolerance inducing pathway in this subgroup. These results were confirmed in a separate cohort of 21 Vietnamese gastric carcinoma samples using qRT-PCR and on tissue samples using in situ hybridization and immunohistochemistry. Lastly, a panel of tumor suppressors and candidate oncogenes were expressed at lower levels in hiEBVaGC versus EBV-low and EBV-negative gastric cancers suggesting the direct regulation of tumor pathways by EBV.

Thaker AI, Rao MS, Bishnupuri KS, et al.
IDO1 metabolites activate β-catenin signaling to promote cancer cell proliferation and colon tumorigenesis in mice.
Gastroenterology. 2013; 145(2):416-25.e1-4 [PubMed] Free Access to Full Article Related Publications
BACKGROUND & AIMS: Indoleamine 2,3 dioxygenase-1 (IDO1) catabolizes tryptophan along the kynurenine pathway. Although IDO1 is expressed in inflamed and neoplastic epithelial cells of the colon, its role in colon tumorigenesis is not well understood. We used genetic and pharmacologic approaches to manipulate IDO1 activity in mice with colitis-associated cancer and human colon cancer cell lines.
METHODS: C57Bl6 wild-type (control), IDO1-/-, Rag1-/-, and Rag1/IDO1 double-knockout mice were exposed to azoxymethane and dextran sodium sulfate to induce colitis and tumorigenesis. Colitis severity was assessed by measurements of disease activity, cytokine levels, and histologic analysis. In vitro experiments were conducted using HCT 116 and HT-29 human colon cancer cells. 1-methyl tryptophan and small interfering RNA were used to inhibit IDO1. Kynurenine pathway metabolites were used to simulate IDO1 activity.
RESULTS: C57Bl6 mice given pharmacologic inhibitors of IDO1 and IDO1-/- mice had lower tumor burdens and reduced proliferation in the neoplastic epithelium after administration of dextran sodium sulfate and azoxymethane than control mice. These reductions also were observed in Rag1/IDO1 double-knockout mice compared with Rag1-/- mice (which lack mature adaptive immunity). In human colon cancer cells, blockade of IDO1 activity reduced nuclear and activated β-catenin, transcription of its target genes (cyclin D1 and Axin2), and, ultimately, proliferation. Exogenous administration of IDO1 pathway metabolites kynurenine and quinolinic acid led to activation of β-catenin and proliferation of human colon cancer cells, and increased tumor growth in mice.
CONCLUSIONS: IDO1, which catabolizes tryptophan, promotes colitis-associated tumorigenesis in mice, independent of its ability to limit T-cell-mediated immune surveillance. The epithelial cell-autonomous survival advantage provided by IDO1 to colon epithelial cells indicate its potential as a therapeutic target.

Mittal D, Kassianos AJ, Tran LS, et al.
Indoleamine 2,3-dioxygenase activity contributes to local immune suppression in the skin expressing human papillomavirus oncoprotein e7.
J Invest Dermatol. 2013; 133(12):2686-94 [PubMed] Free Access to Full Article Related Publications
Chronic infection of anogenital epithelium with human papillomavirus (HPV) promotes development of cancer. Many pathogens evoke immunosuppressive mechanisms to enable persistent infection. We have previously shown that grafted skin expressing HPV16 E7 oncoprotein from a keratin-14 promoter (K14E7) is not rejected by a syngeneic, immunocompetent host. In this study we show that indoleamine 2,3-dioxygenase (IDO) 1, an IFN-γ-inducible immunoregulatory molecule, is more highly expressed by langerin(-ve) dermal dendritic cells (DCs) from K14E7 skin than nontransgenic control skin. Furthermore, inhibiting IDO activity using 1-methyl-dl-tryptophan (1-D/L-MT) promotes K14E7 skin graft rejection. Increased IDO1 expression and activity in K14E7 skin requires IFN-γ and invariant natural killer T (iNKT) cells, both of which have been shown to negatively regulate T-cell effector function and suppress K14E7 graft rejection. Furthermore, DCs from K14E7 skin express higher levels of IFN-γ receptor (IFN-γR) than DCs from control skin. K14E7 transgenic skin recruits significantly higher numbers of DCs, independent of IFN-γ and IFN-γR expression. Consistent with these observations in a murine model, we found higher expression of IDO1 and IFN-γ but not IDO2 in the cervical epithelium of patients with HPV-associated cervical intraepithelial neoplasia (CIN) 2/3. Our data support a hypothesis that induction of IDO1 in HPV-infected skin contributes to evasion of host immunity.

Sioud M, Saebøe-Larssen S, Hetland TE, et al.
Silencing of indoleamine 2,3-dioxygenase enhances dendritic cell immunogenicity and antitumour immunity in cancer patients.
Int J Oncol. 2013; 43(1):280-8 [PubMed] Related Publications
Dendritic cells (DCs) are being explored as a therapeutic vaccine for cancers. However, their immunogenic potential is limited by the presence of immunosuppressive factors. Among these factors is the tryptophan-degrading enzyme indoleamine 2,3-dioxygenase (IDO). In this study, we have investigated the safety, immunogenicity and clinical response of IDO-silenced DC vaccine in four patients with gynecological cancers. DCs were transfected with IDO small interfering RNA and mRNA encoding human telomerase reverse transcriptase (hTERT) or survivin, two universal tumour antigens. Silencing of IDO in DCs did not affect the expression of the co-stimulatory molecules CD80 and CD86, but enhanced the expression of the CCR7 and CD40 molecules. IDO-silenced DCs showed superior potency to activate allogeneic T cells compared to their IDO-positive counterparts. The immunisation with this novel DC cancer vaccine was well tolerated and all patients developed delayed-type hypersensitivity skin reaction and specific T-cell response against hTERT and survivin tumour antigens. Perhaps most importantly, the immune response seen in the patients was related to objective clinical response. Thus, IDO silencing can enhance the immunogenic function of DCs in vitro and in vivo. Overall, the data provide proof-of-principle that immunisation with IDO-silenced DC vaccine is safe and effective in inducing antitumour immunity.

Morscio J, Dierickx D, Ferreiro JF, et al.
Gene expression profiling reveals clear differences between EBV-positive and EBV-negative posttransplant lymphoproliferative disorders.
Am J Transplant. 2013; 13(5):1305-16 [PubMed] Related Publications
Posttransplant patients are at risk of developing a potentially life-threatening posttransplantation lymphoproliferative disorder (PTLD), most often of diffuse large B cell lymphoma (DLBCL) morphology and associated with Epstein-Barr Virus (EBV) infection. The aim of this study was to characterize the clinicopathological and molecular-genetic characteristics of posttransplant DLBCL and to elucidate whether EBV(+) and EBV(-) posttransplant DLBCL are biologically different. We performed gene expression profiling studies on 48 DLBCL of which 33 arose posttransplantation (PT-DLBCL; 72% EBV+) and 15 in immunocompetent hosts (IC-DLBCL; none EBV+). Unsupervised hierarchical analysis showed clustering of samples related to EBV-status rather than immune status. Except for decreased T cell signaling these cases were inseparable from EBV(-) IC-DLBCL. In contrast, a viral response signature clearly segregated EBV(+) PT-DLBCL from EBV(-) PT-DLBCL and IC-DLBCL cases that were intermixed. The broad EBV latency profile (LMP1+/EBNA2+) was expressed in 59% of EBV(+) PT-DLBCL and associated with a more elaborate inflammatory response compared to intermediate latency (LMP1+/EBNA2-). Inference analysis revealed a role for innate and tolerogenic immune responses (including VSIG4 and IDO1) in EBV(+) PT-DLBCL. In conclusion we can state that the EBV signature is the most determining factor in the pathogenesis of EBV(+) PT-DLBCL.

Chakraborty NG, Yadav M, Dadras SS, et al.
Analyses of T cell-mediated immune response to a human melanoma-associated antigen by the young and the elderly.
Hum Immunol. 2013; 74(5):640-7 [PubMed] Related Publications
Elderly cancer patients are often excluded from immune-based clinical trials and therapies based on the belief that they respond poorly to tumor antigens. Using melanoma as a model and melanoma related Mart-127-35 epitope specific T cell receptor (TCR) engineered T cells as a tool we compared the T cell responses from young and elderly to the Mart-127-35 epitope, ex vivo. We also compared the natural Treg (nTreg) activities and the expression of a number of genes associated with immune response by quantitative real-time reverse Transcription Polymerase Chain Reaction (qRTPCR) in formalin fixed primary melanomas, in situ. We detected a significant difference in CD8(+) T cell response to Flu antigen (influenza matrix peptide Flu MP58-66), but the responses of the two cohorts to melanoma antigen were comparable. nTreg activities in the elderly was significantly compromised. The qPCR analyses of tissues from elderly patients revealed lower levels of Fox-P3 expression but comparable levels of expression of IL-2, IFNγ, TNFα, IL-4, IL-10, IDO, and TGFβ. These findings indicate that elderly patients might be capable of responding to tumor antigens, and need not be excluded from immune-based therapies or clinical trials.

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