Tumor growth-promoting properties of macrophage migration inhibitory factor (MIF)

A functional heteromeric MIF receptor formed by CD74 and CXCR4

MIF is a chemokine-like inflammatory mediator that triggers leukocyte recruitment by binding to CXCR2 and CXCR4. MIF also interacts with CD74/invariant chain, a single-pass membrane-receptor. We identified complexes between CD74 and CXCR2 with a role in leukocyte recruitment. It is unknown whether CD74 also binds to CXCR4. We demonstrate that CD74/CXCR4 complexes formed when CD74 was expressed with CXCR4 in HEK293 cells. Expression of CD74-variants lacking an ER-retention signal showed CD74/CXCR4 complexes at the cell surface. Importantly, endogenous CD74/CXCR4 complexes were isolated by co-immunoprecipitation from monocytes. Finally, MIF-stimulated CD74-dependent AKT activation was blocked by anti-CXCR4 and anti-CD74 antibodies and AMD3100, whereas CXCL12-stimulated AKT activation was not reduced by anti-CD74. Thus, CD74 forms functional complexes with CXCR4 that mediate MIF-specific signaling.

Glucocorticoid-induced MIF expression by human CEM T cells

Macrophage migration inhibitory factor (MIF) is an upstream activator of the immune response that counter-regulates the immunosuppressive effects of glucocorticoids. While MIF is released by cells in response to diverse microbial and invasive stimuli, evidence that glucocorticoids in low concentrations also induce MIF secretion suggests an additional regulatory relationship between these mediators. We investigated the expression of MIF from the human CEM T cell line, which exists in two well-characterized, glucocorticoid-sensitive (CEM-C7) and glucocorticoid-resistant (CEM-C1) variant clones. Dexamethasone in low concentrations induced MIF secretion from CEM-C7 but not CEM-C1 T cells by a bell-shaped dose response that was similar to that reported previously for the release of MIF by monocytes/macrophages. Glucocorticoid stimulation of CEM-C7 T cells was accompanied by an MIF transcriptional response, which by promoter analysis was found to involve the GRE and ATF/CRE transcription factor binding sites. These data support a glucocorticoid-mediated MIF secretion response by T cells that may contribute to the regulation of the adaptive immune response.

Activation of nuclear factor kappa B and induction of migration inhibitory factor in tumors by surgical stress of laparotomy versus carbon dioxide pneumoperitoneum: an animal experiment

BACKGROUND

Surgical trauma may be associated with enhanced tumor growth and establishment. The authors studied the effect of carbon dioxide (CO(2)) pneumoperitoneum versus laparotomy on tumor necrosis factor-alpha (TNFalpha), migration inhibitory factor (MIF) expression, and nuclear factor kappa B (NFkappaB) activity in human gastric cancer.

METHODS

Nude mice were inoculated intraperitoneally with human gastric cancer cells (MKN45). Then laparotomy, CO(2) pneumoperitoneum, and anesthesia alone were performed randomly. Tumor growth and associated TNFalpha and MIF expression and NFkappaB activity were determined.

RESULTS

Total tumor weight, especially at the anterior abdominal wall, was higher after laparotomy than after CO(2) pneumoperitoneum (p < 0.05). The mRNA expression of TNFalpha was higher 24 and 48 h after laparotomy than after CO(2) pneumoperitoneum (p < 0.05 and p < 0.01, respectively). At all the examined time points, MIF mRNA expression also was higher after laparotomy than after CO(2) pneumoperitoneum (p < 0.05 until 1 week or p < 0.01 at 2 weeks). The NFkappaB protein was more activated after laparotomy than after CO(2) pneumoperitoneum 6 h subsequent to surgical procedures.

CONCLUSION

After CO(2) pneumoperitoneum, tumors have less TNFalpha and MIF expression and less NFkappaB activity than after laparotomy. This may be associated with less tumor growth, supporting minimal invasive techniques in gastrointestinal oncologic surgery.

Dual role of macrophage migration inhibitory factor (MIF) in human breast cancer

Background

Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine and mediator of acute and chronic inflammatory diseases. MIF is overexpressed in various tumours and has been suggested as a molecular link between chronic inflammation and cancer. MIF overexpression is observed in breast cancer but its causal role in the development of this tumour entity is unclear.

Methods

MIF levels in breast cancer cell lines were determined by ELISA and Western blot. CD74 was measured by Western blot, fluorescence microscopy and flow cytometry. Cell proliferation was studied by BrdU incorporation, cell adhesion by Matrigel adhesion assay, and cell invasion by migration assay through Matrigel-coated filters using the Transwell system. MIF expression in primary human breast cancers was measured by tissue microarray and a semi-quantitative immunoreactivity score (IRS) and comparison with histopathological parameters and patient outcome data.

Results

MIF was abundantly expressed in the non-invasive breast cancer cell lines MDA-MB-468 and ZR-75-1, but not in invasive MDA-MB-231 cells, which in turn expressed higher levels of the MIF-receptor CD74. Stimulation with exogenous MIF led to a dramatic upregulation of MIF secretion (50-fold) in MDA-MB-231 cells. Autocrine MIF promoted tumour cell proliferation, as indicated by blockade of MIF or CD74 in MDA-MB-231 and MDA-MB-468, and MDA-MB-231 invasiveness was enhanced by exogenous MIF. We correlated the expression of MIF with histopathological parameters and patient outcome data, using a tissue microarray of 175 primary invasive breast cancers and 35 normal control tissues. MIF was upregulated in breast cancer versus normal tissue (median IRS = 8 versus 6). MIF expression showed positive correlations with progesterone (p = 0.006) and estrogen (p = 0.028) receptor expression, markers of a favourable prognosis and a negative correlation to tumour size (p = 0.007). In line with these data, disease-specific overall (OS) as well as recurrence-free (RFS) survival was significantly improved in breast cancer patients with abundant cytosolic MIF expression compared to MIF low expressers (5-year OS = 67% versus 50%, p = 0.0019; 5-year RFS = 52% versus 36%, p = 0.0327).

Conclusion

We conclude that intracellular expression of MIF in breast cancer cells is beneficial, whereas extracellular MIF may play a pro-oncogenic role in promoting breast cancer cell-stroma interactions.

The role of macrophage inhibitory factor in tumorigenesis and central nervous system tumors

Macrophage migration inhibitory factor (MIF) has been described as a protein that plays an important role in both innate and acquired immunity. Further research has shown that MIF plays a particularly critical part in cell cycle regulation and therefore in tumorigenesis as well. Over the past few years, the significance of the role of MIF in a variety of both solid and hematologic tumors has been established. More recently, interest has increased in the role of MIF in the development of central nervous system (CNS) tumors, in which it appears to influence cell cycle control. In addition, MIF has been identified as an essential actor in metastasis and angiogenesis. Vascular growth factor concentration raises because of increased levels of MIF in brain tumors. Recently, the MIF receptor complex has been described, and it appears that this may be a suitable drug target for treatment of brain tumors. In light of these findings, the authors chose to conduct a systematic search for information regarding MIF that has been published within the past 15 years using the terms "inflammation," "glioblastoma," "brain tumor," "astrocytoma," "microglia," "glioblastoma," "immune system and brain tumors," "glioblastoma and MIF," and "brain tumor and MIF." The aim of this article was thus to present a detailed review of current knowledge regarding the role of MIF in CNS tumor pathophysiology.

Proliferation of NS0 cells in protein-free medium: the role of cell-derived proteins, known growth factors and cellular receptors

NS0 cells proliferate without external supply of growth factors in protein-free media. We hypothesize that the cells produce their own factors to support proliferation. Understanding the mechanisms behind this autocrine regulation of proliferation may open for the novel approaches to improve animal cell processes. The following proteins were identified in NS0 conditioned medium (CM): cyclophilin A, cyclophilin B (CypB), cystatin C, D-dopachrome tautomerase, IL-25, isopentenyl-diphosphate delta-isomerase, macrophage migration inhibitory factor (MIF), beta(2)-microglobulin, Niemann pick type C2, secretory leukocyte protease inhibitor, thioredoxin-1, TNF-alpha, tumour protein translationally controlled 1 and ubiquitin. Further, cDNA microarray analysis indicated that the genes for IL-11, TNF receptor 6, TGF-beta receptor 1 and the IFN-gamma receptor were transcribed. CypB, IFN-alpha/beta/gamma, IL-11, IL-25, MIF, TGF-beta and TNF-alpha as well as the known growth factors EGF, IGF-I/II, IL-6, leukaemia inhibitory factor and oncostatin M (OSM) were excluded as involved in autocrine regulation of NS0 cell proliferation. The receptors for TGF-beta, IGF and OSM are however present in NS0 cell membranes since TGF-beta(1) caused cell death, and IGF-I/II and OSM improved cell growth. Even though no ligand was found, the receptor subunit gp130, active in signal transduction of the IL-6 like proteins, was shown to be essential for NS0 cells as demonstrated by siRNA gene silencing.

A fluorinated analog of ISO-1 blocks the recognition and biological function of MIF and is orally efficacious in a murine model of colitis

A promising therapeutic approach to diminish pathological inflammation is to inhibit the synthesis and/or biological activity of macrophage migration inhibitory factor (MIF). Prior studies have shown that intraperitoneal administration of small-molecule inhibitors targeting the catalytic pocket of MIF (e.g., ISO-1) elicits a therapeutic effect in mouse inflammation models. However, it remains to be elucidated whether these tautomerase activity inhibitors block the synthesis and/or biological activity of MIF. In this study, we investigated and compared the activity of representative MIF inhibitors from isoxazole series (fluorinated analog of ISO-1; ISO-F) and substituted quinoline series (compound 7E; 7E). Our results demonstrate that ISO-F is a more potent MIF inhibitor than 7E. Both ISO-F and 7E do not inhibit MIF synthesis but "bind-onto" MIF thereby blocking its recognition. However, in contrast to 7E, ISO-F docks well in the active site of MIF and also has a stronger binding affinity towards MIF. In line with these observations, ISO-F, but not 7E, robustly inhibits the biological function of MIF. Most importantly, ISO-F, when administered orally in a therapeutic regimen, significantly suppresses dextran sulphate sodium (DSS)-induced murine colitis. This study, which provides mechanistic insights into the anti-inflammatory efficacy of ISO-F, is the first documented report of in vivo anti-inflammatory efficacy of a MIF inhibitor upon oral administration. Moreover, the findings from this study reinforce the potential of catalytic site of MIF as a target for eliciting therapeutic effect in inflammatory disorders. Compounds (e.g., ISO-F) that block not only the recognition but also the biological function of MIF are potentially attractive for reducing pathological inflammation.

Expression of CD74, the receptor for macrophage migration inhibitory factor, in non-small cell lung cancer

Macrophage migration inhibitory factor (MIF) is a multifunctional cytokine that is overexpressed in lung cancer. The MIF receptor was recently discovered and found to be the invariant chain of the HLA class II molecule, CD74. We hypothesized that the expression of this receptor-ligand pair in lung cancer is associated with the angiogenic activity and level of CXC chemokine expression in human specimens of non-small cell lung cancer. We, therefore, performed immunolocalization of CD74 and compared it with the localization of MIF in non-small cell lung cancer to determine their respective locations, as well as the relationship between the co-expression of MIF-CD74 and angiogenic CXC chemokines with tumor angiogenesis. We found intense CD74 expression by immunohistochemistry in 57 of 70 tumors with minimal to no staining in the remaining 13 tumors. Comparing the localization of CD74 with its putative ligand, MIF, we found that CD74 and MIF were co-expressed in tumors in close proximity, and that co-expression of the MIF-CD74 pair was associated with both higher levels of tumor-associated angiogenic CXC chemokines (ie, the ELR score) and greater vascularity compared with tumors in which MIF-CD74 co-expression was not present. We also found that MIF induced angiogenic CXC chemokine expression in an autocrine manner in vitro, a function that was specifically inhibited by antibodies to CD74.

Direct interaction between NM23-H1 and macrophage migration inhibitory factor (MIF) is critical for alleviation of MIF-mediated suppression of p53 activity

Macrophage migration inhibitory factor (MIF) is a pluripotent cytokine that is involved in host immune and inflammatory responses, as well as tumorigenesis. However, the regulatory mechanism of MIF function is unclear. Here we report that the NM23-H1 interacts with MIF in cells, as demonstrated by cotransfection and coimmunoprecipitation experiments. Analysis of cysteine (Cys) to serine (Ser) substitution mutants of NM23-H1 (C4S, C109S, and C145S) and MIF (C57S, C60S, and C81S) revealed that Cys(145) of NM23-H1 and Cys(60) of MIF are responsible for complex formation. NM23-H1-MIF complexes were dependent on reducing conditions, such as the presence of dithiothreitol or beta-mercaptoethanol, but not H(2)O(2). NM23-H1 alleviated the MIF-mediated suppression of p53-induced apoptosis and cell cycle arrest by promoting the dissociation of MIF from MIF-p53 complexes. In addition, NM23-H1 significantly inhibited the MIF-induced proliferation of quiescent NIH 3T3 cells through a direct interaction with MIF, and decreased the MIF-induced activation of phosphatidylinositol 3-kinase/PDK1 and p44/p42 extracellular signal-regulated (ERK) mitogen-activated protein kinase. The results of the current study suggest that the NM23-H1 functions as a negative regulator of MIF.

Zinc adaptation and resistance to cadmium toxicity in mammalian cells: molecular insight by proteomic analysis

To identify proteins involved in cellular adaptive responses to zinc, a comparative proteome analysis between a previously developed high zinc- and cadmium-resistant human epithelial cell line (high zinc-resistant HeLa cells, HZR) and the parental HeLa cells has been carried out. Differentially produced proteins included cochaperones, proteins associated with oxido-reductase activities, and ubiquitin. Biochemical pathways to which these proteins belong were probed for their involvement in the resistance of both cell lines against cadmium toxicity. Among ER stressors, thapsigargin sensitized HZR cells, but not HeLa cells, to cadmium toxicity more acutely than tunicamycin, implying that these cells heavily relied on proper intracellular calcium distribution. The similar sensitivity of both HeLa and HZR cells to inhibitors of the proteasome, such as MG-132 or lactacystin, excluded improved proteasome activity as a mechanism associated with zinc adaptation of HZR cells. The enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD) was overproduced in HZR cells as compared to HeLa cells. It transforms HPP to homogentisate in the second step of tyrosine catabolism. Inhibition of HPPD decreased the resistance of HZR cells against cadmium, but not that of HeLa cells, suggesting that adaptation to zinc overload and increased HPP removal are linked in HZR cells.

Expression of macrophage migration inhibitory factor by neuroblastoma leads to the inhibition of antitumor T cell reactivity in vivo

Neuroblastomas and many other solid tumors produce high amounts of macrophage migration inhibitory factor (MIF), which appears to play a role in tumor progression. We found that MIF expression in neuroblastoma inhibits T cell proliferation in vitro, raising the possibility that MIF promotes tumorigenesis, in part, by suppressing antitumor immunity. To examine whether tumor-derived MIF leads to suppression of T cell immunity in vivo, we generated MIF-deficient neuroblastoma cell lines using short hairpin small interfering RNAs (siRNA). The MIF knockdown (MIFKD) AGN2a neuroblastoma cells were more effectively rejected in immune-competent mice than control siRNA-transduced or wild-type AGN2a. However, the increased rejection of MIFKD AGN2a was not observed in T cell-depleted mice. MIFKD tumors had increased infiltration of CD8(+) and CD4(+) T cells, as well as increased numbers of macrophages, dendritic cells, and B cells. Immunization with MIFKD AGN2a cells significantly increased protection against tumor challenge as compared with immunization with wild-type AGN2a, and the increased protection correlated with elevated frequencies of tumor-reactive CD8(+) T cells in the lymphoid tissue of treated animals. Increased numbers of infiltrating tumor-reactive CD8(+) T cells were also observed at the site of tumor vaccination. In vitro, treatment of AGN2a-derived culture supernatants with neutralizing MIF-specific Ab failed to reverse T cell suppressive activity, suggesting that MIF is not directly responsible for the immune suppression in vivo. This supports a model whereby MIF expression in neuroblastoma initiates a pathway that leads to the suppression of T cell immunity in vivo.

Differentiation of the bovine dominant follicle from the cohort upregulates mRNA expression for new tissue development genes

This study was designed to identify genes that regulate the transition from FSH- to LH-dependent development in the bovine dominant follicle (DF). Serial analysis of gene expression (SAGE) was used to compare the transcriptome of granulosa cells isolated from the most oestrogenic growing cohort follicle (COH), the newly selected DF and its largest subordinate follicle (SF) which is destined for atresia. Follicle diameter, follicular fluid oestradiol (E) and E:progesterone ratio confirmed follicle identity. Results show that there are 93 transcript species differentially expressed in DF granulosa cells, but only 8 of these encode proteins known to be involved in DF development. Most characterised transcripts upregulated in the DF are from tissue development genes that regulate cell differentiation, proliferation, apoptosis, signalling and tissue remodelling. Semiquantitative real-time PCR analysis confirmed seven genes with upregulated (P≤0.05) mRNA expression in DF compared with both COH and SF granulosa cells. Thus, the new genes identified by SAGE and real-time PCR, which show enhanced mRNA expression in the DF, may regulate proliferation (cyclin D2;CCND2), prevention of apoptosis or DNA damage (growth arrest and DNA damage-inducible, β;GADD45B), RNA synthesis (splicing factor, arginine/serine rich 9;SFRS9) and unknown processes associated with enhanced steroidogenesis (ovary-specific acidic protein; DQ004742) in granulosa cells of DF at the onset of LH-dependent development. Further studies are required to show whether the expression of identified genes is dysregulated when abnormalities occur during DF selection or subsequent development.

Rac activation is associated with hepatocellular carcinoma metastasis by up-regulation of vascular endothelial growth factor expression

PURPOSE

Hepatocellular carcinoma (HCC) is associated with a propensity for vascular invasion and metastasis, which contribute to poor prognosis. Angiogenesis is a crucial process contributing to tumor growth and metastasis. Recently, Rac has been suggested to play a role in angiogenesis. However, the actual role of Rac in HCC angiogenesis remains unclear. Given that vascular endothelial growth factor (VEGF) is an important angiogenic factor in HCC, the purpose of this study was to evaluate the possible correlation between Rac activation and VEGF expression in HCC tumor samples, as well as the mechanism involved in Rac-induced HCC angiogenesis.

EXPERIMENTAL DESIGN

We evaluated Rac and VEGF expression in the HCC tissue microarray of paired primary and metastatic HCC samples using immunohistochemical staining. The role of Rac-induced HCC angiogenesis was also evaluated in vitro in HCC cell lines.

RESULTS

We first showed that activation of Rac was correlated with HCC metastasis (P<0.001), and its expression was significantly correlated with VEGF expression by tissue microarray. Ectopic Rac-dominant active transfection in Hep3B cells increased VEGF secretion, which induced the morphologic change and proliferation of human umbilical vein endothelial cells, resulting in the promotion of angiogenesis. Rac induced the transcriptional activation of VEGF by direct interaction with hypoxia-inducible factor-1alpha (HIF-1alpha) expression. In hypoxic conditions, Rac promoted angiogenesis through an increase in HIF-1alpha stabilization.

CONCLUSION

This study shows that Rac is a novel angiogenic factor for HCC through the enhancement of HIF-1alpha protein stability, which provides a possible therapeutic target in the development of inhibitors of angiogenesis.

Proteomic analysis of microvesicles derived from human colorectal cancer cells

Microvesicles (MV) are membrane vesicles secreted from the plasma and endosomal membrane compartment by various cell types such as hematopoietic, epithelial, and tumor cells. Actively growing tumor cells shed MV, and the rate of shedding increases in malignant tumors. Although recent progress in this area has revealed that tumor-derived MV play multiple roles in tumor growth and metastasis via immune escape, tumor invasion, and angiogenesis, the mechanism of vesicle formation and the biological roles of tumor-derived MV are not understood. Here, we report the first global proteomic analysis of highly purified MV from human colorectal cancer cells. Using 1D SDS gel electrophoresis and nano-LC-MS/MS analyses, we identified a total of 547 microvesicular proteins from three independent experiments with high confidence; 416 proteins were identified at least in two trials, including 181 as yet unreported proteins. We identified 49 proteins involved in the biogenesis of MV, including annexins, ADP-ribosylation factors, and Rab proteins. We also identified 28 proteins that may function in tumorigenesis via promotion of migration, invasion, and growth of tumor cells, immune modulation, metastasis, and angiogenesis. Taken together with previously reported results, our observations suggest that tumor-derived MV may act as communicasomes, that is, extracellular organelles that play diverse roles in intercellular communication. This information will help elucidate the biogenesis and functions of tumor-derived MV, and aid in the development of effective vaccines for various cancers, including colorectal cancer.

Macrophage migration inhibitory factor (MIF) promotes fibroblast migration in scratch-wounded monolayers in vitro

MIF was recently redefined as an inflammatory cytokine, which functions as a critical mediator of diseases such as septic shock, rheumatoid arthritis, atherosclerosis, and cancer. MIF also regulates wound healing processes. Given that fibroblast migration is a central event in wound healing and that MIF was recently demonstrated to promote leukocyte migration through an interaction with G-protein-coupled receptors, we investigated the effect of MIF on fibroblast migration in wounded monolayers in vitro. Transient but not permanent exposure of primary mouse or human fibroblasts with MIF significantly promoted wound closure, a response that encompassed both a proliferative and a pro-migratory component. Importantly, MIF-induced fibroblast activation was accompanied by an induction of calcium signalling, whereas chronic exposure with MIF down-regulated the calcium transient, suggesting receptor desensitization as the underlying mechanism.

Macrophage migration inhibitory factor (MIF) gene polymorphisms are associated with increased prostate cancer incidence

Recurrent or persistent inflammation has emerged as an important factor in cancer development. Overexpression of macrophage migration inhibitory factor (MIF), an upstream regulator of innate immunity with pleiotropic effects on cell proliferation, has been implicated in prostate cancer (CaP). Two polymorphisms in the promoter of the MIF gene (-173G to C transition and seven copies of the -794 CATT repeat) are associated with increased MIF expression in vivo and poor prognosis in autoimmune diseases. We conducted a retrospective analysis of 131 CaP patients and 128 controls from a group of Veterans' Administration patients undergoing routine prostate-specific antigen screening. Patients with CaP were enrolled regardless of treatment. Inclusion criteria for the control group were absence of documented diagnosis of cancer and/or chronic inflammation within patient computerized records. Logistic regression demonstrated a significant association between CaP and the -173G/C, the -173C/C and the -794 7-CATT MIF polymorphisms (P<0.001). Patients with the -794 7-CATT allele had an increased risk of CaP recurrence at 5 years. Individuals with -173G/C, -173C/C and -794 7-CATT MIF genotypes have an increased incidence of CaP and these genotypes may serve as an independent marker for cancer recurrence.

Structural and functional characterization of a secreted hookworm Macrophage Migration Inhibitory Factor (MIF) that interacts with the human MIF receptor CD74

Hookworms, parasitic nematodes that infect nearly one billion people worldwide, are a major cause of anemia and malnutrition. We hypothesize that hookworms actively manipulate the host immune response through the production of specific molecules designed to facilitate infection by larval stages and adult worm survival within the intestine. A full-length cDNA encoding a secreted orthologue of the human cytokine, Macrophage Migration Inhibitory Factor (MIF) has been cloned from the hookworm Ancylostoma ceylanicum. Elucidation of the three-dimensional crystal structure of recombinant AceMIF (rAceMIF) revealed an overall structural homology with significant differences in the tautomerase sites of the human and hookworm proteins. The relative bioactivities of human and hookworm MIF proteins were compared using in vitro assays of tautomerase activity, macrophage migration, and binding to MIF receptor CD74. The activity of rAceMIF was not inhibited by the ligand ISO-1, which was previously determined to be an inhibitor of the catalytic site of human MIF. These data define unique immunological, structural, and functional characteristics of AceMIF, thereby establishing the potential for selectively inhibiting the hookworm cytokine as a means of reducing parasite survival and disease pathogenesis.

Macrophage migration inhibitory factor expression in ovarian cancer

OBJECTIVE

We evaluated the hypothesis that ovarian cancer patients have significantly higher levels of serum macrophage migration inhibitory factor (MIF).

STUDY DESIGN

MIF levels were determined by enzyme-linked immunosorbent assay (ELISA) in epithelial ovarian cancer cell lines and immortalized normal ovarian surface epithelial cells and in serum of ovarian cancer patients (n = 54) and age-matched healthy women (n = 60). To determine the impact of Toll-like receptor-4 ligation on MIF levels, cells were treated for 48 hours with lipopolysaccharide.

RESULTS

Cancer cells, but not normal cells, secrete significant amounts of MIF. This correlates in vivo, where serum MIF levels are significantly higher in ovarian cancer patients. Treatment of cancer cells with lipopolysaccharide induced a significant increase in MIF secretion.

CONCLUSION

MIF may be relevant in the process of ovarian cancer formation and progression. The events leading to the induction of MIF expression and its contribution to ovarian cancer progression may open new venues for targeted therapy.

Macrophage migration inhibitory factor (MIF) promotes cell survival by activation of the Akt pathway and role for CSN5/JAB1 in the control of autocrine MIF activity

The phosphoinositide-3-kinase (PI3K)/Akt signaling pathway plays an important role in cell survival and the development of cancer. Macrophage migration inhibitory factor (MIF) is a critical inflammatory cytokine that was recently associated with tumorigenesis and that potently inhibits apoptosis. This may involve inhibition of p53-dependent genes, but the initiating molecular mechanism of how MIF controls survival/apoptosis is unknown. Here, we show that MIF prevents apoptosis and promotes tumor cell survival by directly activating the Akt pathway. MIF enhanced Akt activity in primary and immortalized fibroblasts (MEF and NIH/3T3), HeLa cervix carcinoma cells and various breast cancer cell lines. Activation was abolished by kinase inhibitors Ly294002 and PP2 and in Src/Yes/Fyn(SYF)(-/-) and CD74(-/-)(MEFs), while being enhanced in CD74-overexpressing MEFs, demonstrating that the MIF-induced Akt pathway encompasses signaling through the MIF receptor CD74 and the upstream kinases Src and PI3K. Akt was activated by exogenous rMIF and autocrine MIF action, as revealed by experiments in MIF(-/-)MEFs and antibody blockade. siRNA knockdown of CSN5/JAB1, a tumor marker and MIF-binding protein, showed that JAB1 controls autocrine MIF-mediated Akt signaling by inhibition of MIF secretion. Akt activation by MIF led to phosphorylation of the proapoptotic proteins BAD and Foxo3a. Apoptosis inhibition by MIF was functionally associated with Akt activation as it was abolished by overexpression of the Akt pathway inhibitor PTEN and occurred independently of p53. This was shown by studying DNA damage-induced apoptosis in fibroblasts, the Fas death pathway in HeLa cells that do not express functional p53, and etoposide-induced apoptosis in breast carcinoma cells expressing mutant p53. Importantly, dependence of breast cancer cell survival on MIF correlated with Akt activation and the PTEN status of these cells. Thus, MIF can directly promote cell survival through activation of the PI3K/Akt pathway and this effect is critical for tumor cell survival.

Inhibition of macrophage migration inhibitory factor or its receptor (CD74) attenuates growth and invasion of DU-145 prostate cancer cells

Macrophage migration inhibitory factor (MIF), a proinflammatory cytokine, is overexpressed in prostate cancer, but the mechanism by which MIF exerts effects on tumor cells remains undetermined. MIF interacts with its identified membrane receptor, CD74, in association with CD44, resulting in ERK 1/2 activation. Therefore, we hypothesized that increased expression or surface localization of CD74 and MIF overexpression by prostate cancer cells regulated tumor cell viability. Prostate cancer cell lines (LNCaP and DU-145) had increased MIF gene expression and protein levels compared with normal human prostate or benign prostate epithelial cells (p < 0.01). Although MIF, CD74, and CD44 variant 9 expression were increased in both androgen-dependent (LNCaP) and androgen-independent (DU-145) prostate cancer cells, cell surface of CD74 was only detected in androgen-independent (DU-145) prostate cancer cells. Therefore, treatments aimed at blocking CD74 and/or MIF (e.g., inhibition of MIF or CD74 expression by RNA interference or treatment with anti-MIF- or anti-CD74- neutralizing Abs or MIF-specific inhibitor, ISO-1) were only effective in androgen-independent prostate cancer cells (DU-145), resulting in decreased cell proliferation, MIF protein secretion, and invasion. In DU-145 xenografts, ISO-1 significantly decreased tumor volume and tumor angiogenesis. Our results showed greater cell surface CD74 in DU-145 prostate cancer cells that bind to MIF and, thus, mediate MIF-activated signal transduction. DU-145 prostate cancer cell growth and invasion required MIF activated signal transduction pathways that were not necessary for growth or viability of androgen-dependent prostate cells. Thus, blocking MIF either at the ligand (MIF) or receptor (CD74) may provide new, targeted specific therapies for androgen-independent prostate cancer.

Exhaustion is associated with low macrophage migration inhibitory factor expression in patients with coronary artery disease

OBJECTIVE

Macrophage migration inhibitory factor (MIF), a protein secreted by immune cells and the pituitary gland, may be associated with coronary artery disease (CAD) and the mental state of coronary patients. The first origin of MIF suggests positive, the second negative associations. The aim of this study was to explore the direction of the association of MIF with CAD and of MIF with exhaustion, if any.

METHODS

Participants were 194 patients who had been recently treated by percutaneous coronary intervention (PCI) and who were exhausted at the start of the study. Half entered a behavioral intervention program. MIF, C-reactive protein, interleukin (IL)-6, IL-1 receptor antagonist, and neopterin were measured in blood collected 6 weeks after PCI (baseline) and 6 and 18 months after baseline. A single measurement of MIF was also available for 129 age- and sex-matched healthy individuals (reference group).

RESULTS

At baseline, MIF in patients undergoing PCI was significantly lower than in the reference group (p < .01). New cardiac events occurred twice as often in the lowest quartile than in the highest quartile of MIF concentrations. However, the association was not significant (chi(2) = 2.27; df = 3; p = .52). During follow up, MIF concentrations increased significantly in patients undergoing PCI (p < .001). At 18 months, MIF concentrations were significantly lower in the exhausted patients than in the nonexhausted patients (p = .02). hsCRP, IL-1ra, IL-6, and neopter in concentrations did not change over this time period.

CONCLUSIONS

The data are suggestive of a negative association of MIF with CAD and of MIF with exhaustion. The observation that those patients who remained exhausted had lower concentrations of MIF fits into earlier observations that suggested that exhausted coronary patients may be characterized by a hypoactivity of the hypothalamic-pituitary-adrenocortical axis.

Molecular cloning and identification of macrophage migration inhibitory factor (MIF) in teleost fish

Macrophage migration inhibitory factor (MIF) is one of the first cytokines to be identified, which have been emerged to be an important mediator of the innate and adaptive immune system. Although MIF was well characterized in several mammal species, there was still little report in fish. In present study, we cloned the MIF gene from Tetraodon nigroviridis, and identified other six MIF genes from other teleost fishes, Fundulus heteroclitu, Oncorhynchus mykiss, Ictalurus punctatus, Danio rerio, Salmo salar and Haplochromis chilotes. The results showed that the fish MIF genes with the same organization as the mammalians consist of three exons and two introns. Tetraodon MIF gene located within a 1091bp genomic fragment of chromosome 1, transcribed into a 500bp mRNA including 14bp 5' untranslated region (UTR), 348bp ORF and 138bp 3'-UTR. Tetraodon MIF with 115aa has a calculated molecular mass of 12.5kDa and a theoretical pI of 6.81. The deduced amino-acid sequences of the teleost fish MIFs showed 64.1-73.5% sequence identity to mammalian MIFs, 61.5-70.1% to avian MIFs, 55.6-62.4% to amphibian MIFs, 74.4-97.4% among the teleost fishes. Phylogenetic analysis separates the teleost fish MIFs into an exclusive group. Genomic Southern blotting analyses suggest that Tetraodon has one copy of the MIF gene. RT-PCR and real-time PCR analyses reveal that Tetraodon MIF (TnMIF) mRNA was constitutively expressed in 10 selected tissues and induced by lipopolysaccharide (LPS) strikingly in head kidney and spleen. The bioactivity of recombinant TnMIF was tested by macrophage migration inhibition (MMI) assay. The result of MMI assay showed that the recombinant TnMIF inhibited the macrophage cells migration at rate of 35% (P<0.04). These results indicated that MIFs in fish may be involved in immune responses.

Three new serum markers for prostate cancer detection within a percent free PSA-based artificial neural network

BACKGROUND

We aimed to evaluate the value of macrophage inhibitory cytokine 1 (MIC-1), human kallikrein 11 (hK11) migration inhibitor factor (MIF) in comparison to prostate-specific antigen (PSA) and % fPSA and also to develop a % fPSA-based ANN with the new input factors to determine whether these additional markers can further eliminate unnecessary prostate biopsies.

METHODS

Serum samples from 371 patients with prostate cancer (PCa, n=135) or benign prostate hyperplasia (BPH, n=236) within the PSA range 0.5-20 microg/L were analyzed for total PSA, free PSA, MIC-1, hK11, and MIF. 'Leave one out' ANN models with these variables and prostate volume were constructed and compared to logistic regression (LR) and all single parameters.

RESULTS

The discriminatory power of MIC-1, hK11, and MIF was less than that for PSA despite significant differences in BPH compared to PCa patients. At 90% and 95% sensitivity, the artificial neural networks (ANNs) were only significantly better than % fPSA if prostate volume was included.

CONCLUSIONS

ANNs with the novel input factors of MIC-1, MIF, and/or hK11 and additional use of prostate volume demonstrated significant advantage compared with % fPSA and tPSA and may lead to a reduction in unnecessary prostate biopsies.

Macrophage migration inhibitory factor interacts with HBx and inhibits its apoptotic activity

HBx, a transcriptional transactivating protein of hepatitis B virus (HBV), is required for viral infection and has been implicated in virus-mediated liver oncogenesis. However, the precise molecular mechanism remains largely elusive. We used the yeast two-hybrid system to identify that HBx interacts with MIF directly. Macrophage migration inhibitory factor (MIF) is implicated in the regulation of inflammation, cell growth, and even tumor formation. The interaction between HBx and MIF was verified with co-immunoprecipitation, GST pull-down, and cellular colocalization. The expression of MIF was up-regulated in HBV particle producing cell 2.2.15 compared with HepG2 cell. Both HBx and MIF cause HepG2 cell G(0)/G(1) phase arrest, proliferation inhibition, and apoptosis. However, MIF can counteract the apoptotic effect of HBx. These results may provide evidence to explain the link between HBV infection and hepatocellular carcinoma.

Inhibition of tumor growth and metastasis in vitro and in vivo by targeting macrophage migration inhibitory factor in human neuroblastoma

Macrophage migration inhibitory factor (MIF) has been defined as a novel oncogene. Our previous results have shown that MIF may contribute to the progression of neuroblastoma by (a) inducing N-Myc expression and (b) upregulating the expression of angiogenic factors. The aim of this study was to test whether tumor growth could be inhibited by reduction of endogenous MIF expression in neuroblastoma and clarify the molecular mechanisms underlying MIF reduction on the control of neuroblastoma growth. We established human neuroblastoma cell lines stably expressing antisense MIF (AS-MIF) cDNA. These stable transfectants were characterized by cell proliferation, gene expression profile, tumorigenicity and metastasis in vitro and in vivo. Decreased MIF expression was observed after transfection with AS-MIF in neuroblastoma cells and downregulation of MIF expression significantly correlated with decreased expression of N-Myc, Ras, c-Met and TrkB at protein level. Affymetrix microarray analysis revealed that expression of IL-8 and c-met was inhibited and neuroblastoma-favorable genes such as EPHB6 and BLU were upregulated in MIF reduced cells. Neuroblastoma cell growth exhibited a nearly 80% reduction in AS-MIF transfectants in vitro. Furthermore, mice in which tumors formed after subcutaneous injection of AS-MIF transfectants showed a 90% reduction in tumor growth compared to control. Metastasis in mice was also suppressed dramatically. Our data demonstrate that targeting MIF expression is a promising therapeutic strategy in human neuroblastoma therapy, and also identifies the MIF target genes for further study.

Macrophage migration and gene expression in response to tumor hypoxia

Monocytes are recruited into tumors from the circulation along defined chemotactic gradients and they then differentiate into tumor-associated macrophages (TAMs). Recent evidence has shown that large numbers of TAMs are attracted to and retained in avascular and necrotic areas, where they are exposed to tumor hypoxia. At these sites, TAMs appear to undergo marked phenotypic changes with activation of hypoxia-inducible transcription factors, dramatically upregulating the expression of a large number of genes encoding mitogenic, proangiogenic and prometastatic cytokines and enzymes. As a consequence, high TAMs density has been correlated with increased tumor growth and angiogenesis in various tumor types. Since hypoxia is a hallmark feature of malignant tumors and hypoxic tumor cells are relatively resistant to radio- and chemotherapy, these areas have become a target for novel forms of anticancer therapy. These include hypoxia-targeted gene therapy in which macrophages are armed with therapeutic genes that are activated by hypoxia-responsive promoter elements. This restricts transgene expression to hypoxic areas, where the gene product is then released and acts on neighboring hypoxic tumor cells or proliferating blood vessels. In this way, the responses of macrophages to tumor hypoxia can be exploited to deliver potent antitumor agents to these poorly vascularized, and thus largely inaccessible, areas of tumors.

Removing intensity effects and identifying significant genes for Affymetrix arrays in macrophage migration inhibitory factor-suppressed neuroblastoma cells

A semilinear in-slide model is introduced to remove the intensity effect in the scanning process. It is demonstrated that the intensity effect can be estimated accurately and removed effectively. This normalization step is vital for Affymetrix arrays to reveal relevant biological results when comparing gene expression in multiple arrays. The normalized expression ratios are analyzed further by a modified two-sample t test along with a sieved permutation scheme for computing P values. The improved specificity and sensitivity are demonstrated by using a study on the impact of macrophage migration inhibitory factor (MIF) reduction in neuroblastoma cells. With semilinear in-slide model analysis, expression of 166 genes was altered with a P value no greater than 0.001. Among those genes, 44 were altered >2-fold. MIF-regulated genes associated with tumor development including IL-8 and C-met, which are overexpressed in many tumors, were down-regulated in MIF-reduced cells. On the other hand, some tumor-suppressor genes such as EPHB6, visinin-like protein 1 (VSNL-1), and BLU were up-regulated in MIF-reduced cells. In addition, we demonstrated that down-regulation of MIF expression could result in a reduction in cell proliferation and tumor growth in vitro and in vivo. Our data not only demonstrate that targeting MIF expression is a promising therapeutic strategy in human neuroblastoma therapy but also indicate the MIF target genes for additional study.

Link between macrophage migration inhibitory factor and cellular redox regulation

Macrophage migration inhibitory factor (MIF) is an evolutionary conserved 12.5-kDa protein mediator with multiple functions in innate and acquired immunity. Upon leaderless secretion, MIF acts as a typical inflammatory cytokine, but there is no structural homology between MIF and any of the known cytokine protein families. Also, MIF is unique among cytokines in that it exhibits certain endocrine properties and has enzymatic activity. The catalytic thiol-protein oxidoreductase (TPOR) activity of MIF is mediated by a Cys-Ala-Leu-Cys active site between residues 57 and 60 that can undergo reversible intramolecular disulfide formation. Such a redox motif is typically found in TPORs of the thioredoxin (Trx) family of proteins. MIF seems to act as a disulfide reductase, and structure-function analyses of the redox site indicate that this activity is not only observed in vitro, but plays a role in cellular redox homeostasis, apoptosis inhibition, MIF-mediated monocyte/macrophage activation, and possibly the modulation of the activity of MIF-binding proteins. In this Forum review, the biochemical and biological evidence for a role of the TPOR activity for various MIF functions is summarized and discussed. In particular, the marked functional homologies with Trx proteins, the MIF redox/MHC II link, and recent attempts to discern the intra- versus extracellular roles of the MIF TPOR activity are dealt with.

Macrophage migration inhibitory factor stimulates angiogenic factor expression and correlates with differentiation and lymph node status in patients with esophageal squamous cell carcinoma

OBJECTIVE

The objectives of this study were: 1) to examine the expression of macrophage migration inhibitory factor (MIF) in esophageal squamous cell carcinoma (ESCC); 2) to see if a relationship exists between MIF expression, clinicopathologic features, and long-term prognosis; and 3) to ascertain the possible biologic function of MIF in angiogenesis.

SUMMARY BACKGROUND DATA

MIF has been linked to fundamental processes such as those controlling cell proliferation, cell survival, angiogenesis, and tumor progression. Its role in ESCC, and the correlation of MIF expression and tumor pathologic features in patients, has not been elucidated.

METHODS

The expression of MIF in tumor and nontumor tissues was examined by immunohistochemical staining. Concentrations of MIF, vascular endothelial growth factor (VEGF), and interleukin-8 (IL-8) in patients' sera and in the supernatant of tumor cells culture were examined by ELISA. Correlations with clinicopathologic factors were made.

RESULTS

In 72 patients with ESCC, intracellular MIF was overexpressed in esophagectomy specimens. The expression of MIF correlated with both tumor differentiation and lymph node status. The median survival in the low-MIF expression group (<50% positively stained cancer cells on immunohistochemistry) and high expression group (>/=50% positively stained cancer cells) was 28.3 months and 15.8 months, respectively (P = 0.03). The 3-year survival rates for the 2 groups were 37.7% and 12.1%, respectively. MIF expression was related to microvessel density; increased MIF serum levels also correlated with higher serum levels of VEGF. In addition, in vitro MIF stimulation of esophageal cancer cell lines induced a dose-dependent increase in VEGF and IL-8 secretion.

CONCLUSIONS

These results demonstrate, for the first time, that human esophageal carcinomas express and secrete large amounts of MIF. Through its effects on VEGF and IL-8, MIF may serve as an autocrine factor in angiogenesis and thus play an important role in the pathogenesis of ESCC.

Expression of macrophage migration inhibitory factor is associated with enhanced angiogenesis and advanced stage in gastric carcinomas

AIM: Macrophage migration inhibitory factor (MIF) was reported to inactivate p53 and play an essential role in the growth and angiogenesis of tumors that arise at sites of chronic inflammation. Gastric inflammation is a prerequisite for the development of gastric carcinoma (GC), which has recently been linked to Helicobacter pylori (H pylori) infection. This study aimed to investigate clinicopathological significance of MIF expression in GCs.

METHODS: We selected 90 consecutive patients with GCs for investigation of the relation among MIF status, clinicopathological parameters, p53 expression and angiogenesis. MIF and p53 expression was assessed by immunohistochemistry as positive and negative groups. Tumor vascularity was evaluated by counting microvessel density on anti-CD34 stained sections. Expression status of MIF was correlated with determined clinicopathological data, p53 immunoreactivity and microvessel counts.

RESULTS: Strong immunostainings of MIF were observed in the cytoplasm of cancerous cells in 40% (36/90) of cases but not in normal or metaplastic epithelia. There was no statistically significant correlation between MIF expression and age, gender, H pylori infection, tumor location, histological subtypes, lymph node metastasis or p53 expression. Early GC less frequently overexpressed MIF as compared to advanced GCs (4/20 vs 32/70, P = 0.04). A remarkably increased microvessel count was noted in GCs with MIF expression than those without MIF expression (55.1±30.1 vs 31.3±28.8, P = 0.0001).

CONCLUSION: Our results suggest that expression of MIF may contribute to the progression and enhanced angiogenesis in a substantial portion of GCs.

Gene expression changes induced by bismuth in a macrophage cell line

We have investigated the effect of bismuth by autometallography, cell viability, TUNEL assay and microarray analysis of a macrophage cell line. The cells accumulate bismuth in their lysosomes in a time- and dose-dependent manner. Cell viability assays show a significant decrease in the number of viable cells related to both bismuth concentrations and exposure time. TUNEL assays after 12 h and 24 h at a bismuth-citrate concentration of 50 microM revealed the presence of 30% and 70% TUNEL-positive cells, respectively, compared with 8% in the controls. We have analysed gene expression profiles for cells exposed to 50 microM bismuth-citrate and for untreated controls at 12 h and 24 h by microarray analysis, which confirmed that bismuth is a powerful metallothionein inducer. A number of glycolytic enzymes are induced by bismuth, suggesting that bismuth is able to induce "hypoxia-like" stress. BCL2/adenovirus E1B 19-kDa-interacting protein 3 (Bnip3) has been suggested as a regulator of hypoxia-induced cell death independent of caspase-3 activation and cytochrome c release. Bnip3 is up-regulated indicating the involvement of Bnip3 as a possible mechanism for bismuth-induced cell death. Differences have been noticed in cell viability and in the modification of the mRNA expression levels at 12 and 24 h. Only 13 genes are modified at both these times, suggesting a time-dependent molecular cascade in which bismuth-exposed cells enter a dormant stage with mRNA down-regulation being followed by cell death of susceptible cells.

Charge heterogeneity of bovine brain macrophage migration inhibitory factor

Macrophage migration inhibitory factor (MIF) is known as a ubiquitous pluripotent cytokine originally identified for its capacity to inhibit the random migration of macrophages in vitro. It is recognized as an important regulator of the immunological, neuroendocrine and enzymatic processes. MIF is widely expressed in brain, but its role in the nervous system is not yet understood. In the course of the study of the primary structure of bovine brain MIF we have previously identified a number of MIF-related proteins having identical N-terminal sequences. In this paper we report the results of isoelectric focusing of MIF isolated to a homogeneous state from bovine brain that revealed MIF charge heterogeneity. We have detected isoelectric forms of MIF with pI values of 6.9, 7.0, 7.3, and 7.8. The diverse actions of MIF within the immuno-neuroendocrine system is suggested to be a result of its occurrence in different isoforms and oligomerization states.

Macrophage migration inhibitory factor stimulated by Helicobacter pylori increases proliferation of gastric epithelial cells

AIM

Helicobacter pylori (H pylori) is associated with increased gastric inflammatory and epithelial expression of macrophage migration inhibitory factor (MIF) and gastric epithelial cell proliferation. This study aimed at determining whether H pylori directly stimulates release of MIF in monocytes, whether the cag pathogenicity island (PAI) is involved for this function, and whether MIF stimulated by H pylori increases gastric epithelial cell proliferation in vitro.

METHODS

A cytotoxic wild-type H pylori strain (TN2), its three isogenic mutants (TN2Deltacag, TN2DeltacagA and TN2DeltacagE) were co-cultured with cells of a human monocyte cell line, THP-1, for 24 h at different organism/cell ratios. MIF in the supernatants was measured by an ELISA. Cells of a human gastric cancer cell line, MKN45, were then co-cultured with the supernatants, with and without monoclonal anti-MIF antibody for 24 h. The cells were further incubated for 12 h after addition of 3H-thymidine, and the levels of incorporation of 3H-thymidine were measured with a liquid scintillation counter.

RESULTS

The wild-type strain and the isogenic mutants, TN2DeltacagA and TN2 DeltacagE, increased MIF release at organism/cell ratios of 200/1 and 400/1, but not at the ratios of 50/1 and 100/1. However, the mutant TN2delta cag did not increase the release of MIF at any of the four ratios. 3H-thymidine readings for MKN-45 cells were significantly increased with supernatants derived from the wild-type strain and the mutants TN2DeltacagA and TN2DeltacagE, but not from the mutant TN2Deltacag. Moreover, in the presence of monoclonal anti-MIF antibody, the stimulatory effects of the wild-type strain on cell proliferation disappeared.

CONCLUSION

H pylori stimulates MIF release in monocytes, likely through its cag PAI, but not related to cagA or cagE. H pylori-stimulated monocyte culture supernatant increases gastric cell proliferation, which is blocked by anti-MIF antibody, suggesting that MIF plays an important role in H pylori-induced gastric epithelial cell proliferation.

Defining minimum genomic regions of imbalance involved in testicular germ cell tumors of adolescents and adults through genome wide microarray analysis of cDNA clones

Identifying changes in DNA copy number can pinpoint genes that may be involved in tumor development. Here we have defined the smallest overlapping regions of imbalance (SORI) in testicular germ cell tumors other than the 12p region, which has been previously investigated. Definition of the regions was achieved through comparative genomic hybridization (CGH) analysis of a 4559 cDNA clone microarray. A total of 14 SORI were identified, which involved at least five of the 11 samples analysed. Many of these refined regions were previously reported using chromosomal or allelic imbalance studies. The SORI included gain of material from the regions 4q12, 17q21.3, 22q11.23 and Xq22, and loss from 5q33, 11q12.1, 16q22.3 and 22q11. Comparison with parallel chromosomal CGH data supported involvement of most regions. The various SORI span between one and 20 genes and highlight potential oncogenes/tumor suppressor genes to be investigated further.

Binding of JAB1/CSN5 to MIF is mediated by the MPN domain but is independent of the JAMM motif

Macrophage migration inhibitory factor (MIF) binds to c-Jun activation domain binding protein-1 (JAB1)/subunit 5 of COP9 signalosome (CSN5) and modulates cell signaling and the cell cycle through JAB1. The binding domain of JAB1 responsible for binding to MIF is unknown. We hypothesized that the conserved Mpr1p Pad1p N-terminal (MPN) domain of JAB1 may mediate binding to MIF. In fact, yeast two hybrid (YTH) and in vitro translation/coimmunoprecipitation (CoIP) analysis showed that a core MPN domain, which did not cover the functional JAB1/MPN/Mov34 metalloenzyme (JAMM) deneddylase sequence, binds to MIF comparable to full-length JAB1. YTH and pull-down analysis in conjunction with nanobead affinity matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry demonstrated that MIF(50-65) and MPN are sufficient to mediate MIF-JAB1 interaction, respectively. Finally, endogenous CoIP of MIF-CSN6 complexes from mammalian cells demonstrated that MPN is responsible for MIF-JAB1 binding in vivo, and, as CSN6 does not contain a functional JAMM motif, confirmed that the interaction does not require JAMM.

Diagnostic validity of macrophage migration inhibitory factor in serum of patients with prostate cancer: a re-evaluation

BACKGROUND

Recent studies suggest that macrophage migration inhibitory factor (MIF) in serum is of prognostic significance for prostate cancer. The aim of this study was to re-evaluate this hypothesis.

METHODS

Serum MIF levels were measured in healthy men (n = 86), untreated patients with benign prostate hyperplasia (BPH; n = 50), prostate cancer (PCa; n = 163), and after radical prostatectomy for 3 days (n = 5). PCa patients were classified according to the TNM system and the WHO grading scale. Prostate specific antigen (PSA) and C-reactive protein (CRP) were additionally determined.

RESULTS

The MIF concentrations of healthy men and BPH patients did not differ (mean +/- SD, 2.08 +/- 1.08 microg/L vs. 2.04 +/- 1.08 microg/L), whereas the mean value of MIF in PCa patients was significantly decreased (1.77 +/- 1.12 microg/L). There was no any correlation between MIF and PSA (r(s) = -0.049, P = 0.271). MIF concentrations in patients with T1 tumors were higher than in those with T2 tumors (2.29 +/- 1.26 vs. 1.67 +/- 1.11 microg/L; P = 0.044). No any effect of grading was observed. After prostatectomy, the changes of PSA and MIF were not always concordant as MIF partly increased while PSA continuously decreased. Analyses of receiver-operating curves and logistic regressions did not show that MIF alone or MIF related variables (MIF/tPSA; fPSA/(tPSA x MIF); fPSA x MIF/tPSA) could improve specificity or sensitivity to detect prostate cancer in comparison to total PSA.

CONCLUSION

Serum MIF alone or MIF to PSA related variables did not seem suitable for providing additional information on PCa patients. That re-evaluated diagnostic validity of MIF was in contrast to results by another group shown previously.

Mechanisms and effectors of MIF-dependent promotion of tumourigenesis

The importance of secreted cytokines and growth factors in the development and promotion of malignancies is often underestimated. Many different soluble, extracellular gene products participate in processes that collectively contribute to the growth and survival of a developing neoplasm. These secreted molecules can, directly or indirectly, play a central role in uncontrolled tumour cell division, angiogenic stimulation or suppression of tumour cell immune surveillance. One of the first cytokine activities ever described, macrophage migration inhibitory factor (MIF), is unique to these soluble mediators in that it participates in all of these pro-tumourigenic processes. Overexpressed in most tumour types examined, MIF has been shown to promote malignant cell transformation, inhibit tumour cell-specific immune cytolytic responses and strongly enhance neovascularization. Despite this broad array of activities, the elucidation of molecular and cellular mechanisms involved in MIF-dependent bioactions has remained elusive. This review will focus on recently characterized phenotypes and mechanistic effectors thought to be associated with MIF-dependent promotion of neoplastic processes and discuss their relative importance in carcinogenesis.

Elevations in peritoneal fluid macrophage migration inhibitory factor are independent of the depth of invasion or stage of endometriosis

OBJECTIVE

To quantify levels of macrophage migration inhibitory factor (MIF) in the peritoneal fluid (PF) of women with endometriosis, and to correlate these levels with the extent of disease.

DESIGN

Controlled clinical study.

SETTING

Academic medical center.

PATIENT(S)

Peritoneal fluid samples were collected during laparoscopic surgery in 60 women with endometriosis and 16 controls undergoing tubal ligation; 52 of the women with endometriosis had received no hormonal treatment in the 6 months prior to surgery, while 8 were using gonadotropin-releasing hormone (GnRH) agonists.

MAIN OUTCOME MEASURE(S)

Peritoneal fluid migration inhibitory factor (PF MIF) levels.

RESULT(S)

Women with endometriosis had significantly higher PF MIF levels (10.8 +/- 0.9 ng/mL) than controls (3.0 +/- 0.7 ng/mL). However, no correlation existed between MIF levels and the stage of disease (r = 0.05) or the depth of endometriotic invasion (r = 0.08). Moreover, treatment with a GnRH agonist did not suppress PF MIF levels. Peritoneal fluid MIF levels did not vary significantly between the proliferative and secretory phases of the cycle, and did not distinguish women with endometriosis-associated infertility from women with endometriosis-associated pain.

CONCLUSION(S)

Peritoneal fluid migration inhibitory factor levels are markedly elevated in women with endometriosis but are independent of the extent of disease.

Inhibition of macrophage migration inhibitory factor decreases proliferation and cytokine expression in bladder cancer cells

BACKGROUND

The importance of various inflammatory cytokines in maintaining tumor cell growth and viability is well established. Increased expression of the proinflammatory cytokine macrophage migration inhibitory factor (MIF) has previously been associated with various types of adenocarcinoma.

METHODS

MIF IHC was used to localize MIF in human bladder tissue. ELISA and Western blot analysis determined the synthesis and secretion of MIF by human bladder transitional cell carcinoma cells. The effects of MIF inhibitors (high molecular weight hyaluronate (HA), anti-MIF antibody or MIF anti-sense) on cell growth and cytokine expression were analyzed.

RESULTS

Human bladder cancer cells (HT-1376) secrete detectable amounts of MIF protein. Treatment with HA, anti-MIF antibody and MIF anti-sense reduced HT-1376 cell proliferation, MIF protein secretion, MIF gene expression and secreted inflammatory cytokines. Our evidence suggests MIF interacts with the invariant chain, CD74 and the major cell surface receptor for HA, CD44.

CONCLUSIONS

This study is the first to report MIF expression in the human bladder and these findings support a role for MIF in tumor cell proliferation. Since MIF participates in the inflammatory response and bladder cancer is associated with chronic inflammatory conditions, these new findings suggest that neutralizing bladder tumor MIF may serve as a novel therapeutic treatment for bladder carcinoma.

Mechanisms regulating the recruitment of macrophages into hypoxic areas of tumors and other ischemic tissues

The mechanisms responsible for recruiting monocytes from the bloodstream into solid tumors are now well characterized. However, recent evidence has shown that these cells then differentiate into macrophages and accumulate in large numbers in avascular and necrotic areas where they are exposed to hypoxia. This parallels their tendency to congregate in ischemic areas of other diseased tissues such as atherosclerotic plaques and arthritic joints. In tumors, macrophages appear to undergo marked phenotypic changes when exposed to hypoxia and to switch on their expression of a number of mitogenic and proangiogenic cytokines and enzymes. This then promotes tumor growth, angiogenesis, and metastasis. Here, we compare the various mechanisms responsible for monocyte recruitment into tumors with those regulating the accumulation of macrophages in hypoxic/necrotic areas. Because the latter are best characterized in human tumors, we focus mainly on these but also discuss their relevance to macrophage migration in ischemic areas of other diseased tissues. Finally, we discuss the relevance of these mechanisms to the development of novel cancer therapies, both in providing targets to reduce the proangiogenic contribution made by hypoxic macrophages in tumors and in developing the use of macrophages to deliver therapeutic gene constructs to hypoxic areas of diseased tissues.

Upregulation of macrophage migration inhibitory factor contributes to induced N-Myc expression by the activation of ERK signaling pathway and increased expression of interleukin-8 and VEGF in neuroblastoma

Macrophage migration inhibitory factor (MIF) has been linked to fundamental processes such as control of cell proliferation, cell survival, angiogenesis, and tumor progression. The expression of MIF has been reported in several tumors. However, the precise role of MIF in tumor cells remains unclear. In the present study, we investigated the expression pattern and the function of MIF in neuroblastoma. Our results showed that intracellular MIF was upregulated in neuroblastoma tumor tissues and cell lines. MIF protein expression significantly correlated with the grade of tumor differentiation. In addition, we found that MIF induced a significant dose-dependent increase of vascular endothelial growth factor and interleukin-8 secretion. We also observed that an increased MIF expression level correlated with N-Myc protein (the N-myc oncogene product) expression in neuroblastoma tissues. MIF increased the expression of N-myc mRNA and N-Myc protein and induced N-Myc translocation from the cytoplasm to nucleus in neuroblastoma cell lines. MIF-induced N-Myc expression was found to be dependent on ERK signaling pathways. The inhibition of ERK activation reduced MIF-mediated N-Myc expression. These results suggest that MIF may contribute to the progression of neuroblastoma by (a) inducing N-Myc expression and (b) upregulating the expression of angiogenic factors.

Type 1 and type 2 tumor infiltrating effector cell subpopulations in progressive breast cancer

Effector T cells fall into two subpopulations based on cytokine-secretion. Type 1 cells secrete IFN-gamma, whereas type 2 cells secrete IL-4, IL-10, and GM-CSF. NKT cells represent a third subpopulation that secretes similar cytokines and have been associated with immunoregulation. Using the TS/A adenocarcinoma, we assessed the phenotype and kinetics of tumor-infiltrating lymphocytes (TIL) in mice challenged subcutaneously in the mammary region. Flow cytometric analysis shows that T cells do not infiltrate the primary tumor site until days 7-14 following tumor challenge. Both CD4 and CD8 TILs were predominantly CD44(High) and expressed CD25, CD69, and CD95 cell surface activation markers. Activated CD4/CD44(High) TIL numbers reached peak levels at day 21 that precipitously decreased by day 28 whereas corresponding CD8 cell numbers progressively increased, however, at lower levels and with later kinetics. Intracellular cytokine staining showed that greater numbers of IL-4-producing Th2 cells were elicited and with earlier kinetics than that of IFN-gamma-producing Th1 cells. T cells co-expressing DX5 (CD3(+)/DX5(+)) emerged (>21 days), suggesting a recruitment of NK-like T cells at later stages of tumor progression. Moreover, tumors selectively up-regulated TGF-beta, MIF, and IP-10 gene expression at times as early as day 4, with peak levels at day 7 in vivo. Such gene expression remained elevated and correlated with a continued progression in tumor growth suggesting that preferential effector cell recruitment and production of select factors during different stages of tumor maturation may aid in regulating effective endogenous antitumor responses in progressive breast cancer.

Estrogen-inducible uterine flavonoid binding sites: is it time to reconsider?

Epidemiological data support the beneficial effect of plant flavonoids on human health including anti-inflammatory and cancer preventing actions. The phytoestrogen flavonoids might interfere with estrogen action. The possible relations between the steroid- and the flavonoid-signalling in animal and plant cells have been addressed in numerous studies in the past decade. In search for possible sites of conjunction between these phenomena the post-receptor targets must not be disregarded. The estrogen-inducible type II estrogen binding sites of rat uteri have first been reported 25 years ago by Clark and coworkers [Biochem. Biophys. Res. Commun. 81 (1978) 1]. These sites are known to bind catecholic flavonoids with considerable affinity. Behaviour of the tyrosinase-like enzymatic activity associated with these sites appeared reminiscent to the recently described dopachrome oxidase or tautomerase activity exhibited by the cytokine macrophage migration inhibitory factor (MIF) inasmuch as it also accepts a broad range of catecholic melanogenic precursors. Therefore we assessed, whether the known type II ligand flavonoids interfere with the MIF tautomerase. We report here, that luteolin and quercetin have a biphasic effect on the enol-keto conversion of phenylpyruvate mediated by MIF tautomerase. We also demonstrate the presence of MIF immunoreactivity by Western blotting in rat uterine nuclear extracts prepared according to the method that yields high type II binding activity. These data support the possible participation of MIF in type II estrogen binding phenomena.

Normalization and analysis of cDNA microarrays using within-array replications applied to neuroblastoma cell response to a cytokine

The quantitative comparison of two or more microarrays can reveal, for example, the distinct patterns of gene expression that define different cellular phenotypes or the genes that are induced in the cellular response to certain stimulations. Normalization of the measured intensities is a prerequisite of such comparisons. However, a fundamental problem in cDNA microarray analysis is the lack of a common standard to compare the expression levels of different samples. Several normalization protocols have been proposed to overcome the variabilities inherent in this technology. We have developed a normalization procedure based on within-array replications via a semilinear in-slide model, which adjusts objectively experimental variations without making critical biological assumptions. The significant analysis of gene expressions is based on a weighted t statistic, which accounts for the heteroscedasticity of the observed log ratios of expressions, and a balanced sign permutation test. We illustrated the use of the techniques in a comparison of the expression profiles of neuroblastoma cells that were stimulated with a growth factor, macrophage migration inhibitory factor (MIF). The analysis of expression changes at mRNA levels showed that approximately 99 genes were up-regulated and 24 were reduced significantly (P <0.001) in MIF-stimulated neuroblastoma cells. The regulated genes included several oncogenes, growth-related genes, tumor metastatic genes, and immuno-related genes. The findings provide clues as to the molecular mechanisms of MIF-mediated tumor progression and supply therapeutic targets for neuroblastoma treatment.

c-Jun and the dominant-negative mutant, TAM67, induce vimentin gene expression by interacting with the activator Sp1

Vimentin exhibits a complex pattern of developmental- and tissue-specific expression. Since it is aberrantly expressed in metastatic tumors, which have progressed through the epithelial-mesenchymal transition, it has been cited as a marker for tumor progression. Previous studies have indicated that the transcription factor activator protein (AP1) is important in tumor progression. The stable transformation of the MCF7 cell line with the oncogene c-Jun resulted in a cell line (MCF7Jun), which displayed a change in morphology, enhanced migratory and invasive properties, and metastatic behavior. Of the 21 genes whose expression levels were altered in the MCF7Jun cell line, the greatest change in expression occurred for the vimentin gene. Previously, tandem AP1 sites in the promoter were reported to be important for the serum and TPA inducibility of the vimentin gene. However, we find that the AP1 elements only contribute in part to c-Jun activation. Moreover, this activation can be duplicated in COS-1 or S2 cells by expression of c-Jun or TAM67, and is dependent only on the leucine-zipper region of c-Jun. Transient transfection analyses, electrophoretic mobility shift assays, DNA precipitation assays, and coimmunoprecipitation studies suggest that c-Jun is able to synergize with the activator protein Sp1 in binding to GC-box1 to enhance vimentin gene expression.

Macrophage migration inhibitory factor is a cardiac-derived myocardial depressant factor

Macrophage migration inhibitory factor (MIF) is a pluripotent proinflammatory cytokine that is ubiquitously expressed in organs, including the heart. However, no specific role for MIF in modulating cardiac performance has yet been described. Therefore, we examined cardiac MIF expression in mice after LPS challenge (4 mg/kg) and tested the hypothesis that MIF is a mediator of LPS-induced cardiac dysfunction. Western blots of whole heart lysates, as well as immunohistochemistry, documented constitutive MIF protein expression in the heart. Cardiac MIF protein levels significantly decreased after LPS challenge, reaching a nadir at 12 h, and then returned to baseline by 24 h. This pattern was consistent with MIF release from cytoplasmic stores after endotoxin challenge. After release of protein, MIF mRNA levels increased 24-48 h postchallenge. To determine the functional consequences of MIF release, we treated LPS-challenged mice with anti-MIF neutralizing antibodies or isotype control antibodies. Anti-MIF-treated animals had significantly improved cardiac function, as evidenced by a significant improvement in left ventricular (LV) fractional shortening percentage at 8, 12, 24, and 48 h after endotoxin challenge. In support of these findings, perfusion of isolated beating mouse hearts (Langendorff preparation) with recombinant MIF (20 ng/ml) led to a significant decrease in both systolic and diastolic performance [LV pressure (LVP), positive and negative first derivative of LVP with respect to time, and rate of LVP rise at developed pressure of 40 mmHg]. This study demonstrates that MIF mediates LPS-induced cardiac dysfunction and suggests that MIF should be considered a pharmacological target for the treatment of cardiac dysfunction in sepsis and potentially other cardiac diseases.

Macrophage migration inhibitory factor: a regulator of innate immunity

Cytokines are essential effector molecules of innate immunity that initiate and coordinate the cellular and humoral responses aimed, for example, at the eradication of microbial pathogens.

Discovered in the late 1960s as a product of activated T cells, the cytokine macrophage migration inhibitory factor (MIF) has been discovered recently to carry out important functions as a mediator of the innate immune system.

Constitutively expressed by a broad spectrum of cells and tissues, including monocytes and macrophages, MIF is rapidly released after exposure to microbial products and pro-inflammatory mediators, and in response to stress. After it is released, MIF induces pro-inflammatory biological responses that act as a regulator of immune responses.

MIF activates the extracellular signal-regulated kinase 1 (ERK1)/ERK2–mitogen-activated protein kinase pathway, inhibits the activity of JUN activation domain-binding protein 1 (JAB1) — a co-activator of the activator protein 1 (AP1) — upregulates the expression of Toll-like receptor 4 to promote the recognition of endotoxin-expressing bacterial pathogens, sustains pro-inflammatory function by inhibiting p53-dependent apoptosis of macrophages and counter-regulates the immunosuppressive effects of glucocorticoids on immune cells.

As a pro-inflammatory mediator, MIF has been shown to be implicated in the pathogenesis of severe sepsis and septic shock, acute respiratory distress syndrome, and several other inflammatory and autoimmune diseases, including rheumatoid arthritis, glomerulonephritis and inflammatory bowel diseases.

Given its crucial role as a regulator of innate and acquired immunity, pharmacological or immunological modulation of MIF activity might offer new treatment opportunities for the management of acute and chronic inflammatory diseases.

For more than a quarter of a century, macrophage migration inhibitory factor (MIF) has been a mysterious cytokine. In recent years, MIF has assumed an important role as a pivotal regulator of innate immunity. MIF is an integral component of the host antimicrobial alarm system and stress response that promotes the pro-inflammatory functions of immune cells. A rapidly increasing amount of literature indicates that MIF is implicated in the pathogenesis of sepsis, and inflammatory and autoimmune diseases, suggesting that MIF-directed therapies might offer new treatment opportunities for human diseases in the future.

Macrophage migration inhibitory factor: roles in regulating tumor cell migration and expression of angiogenic factors in hepatocellular carcinoma

Macrophage migration inhibitory factor (MIF) may contribute to multiple aspects of tumor progression, including control of cell proliferation, differentiation, cell survival and angiogenesis. However, the potential roles of MIF in regulating hepatocellular carcinoma (HCC) tumor cell migration and the expression of angiogenic factors by HCC tumor cells have not been studied yet. In our study, we reported that intracellular MIF mRNA and protein were overexpressed in HCC tissues compared to nontumor tissues by using in situ hybridization and immunohistochemic staining. HCC tumor cell lines also secreted large amounts of MIF into the supernatants of tumor cell culture. To assess the role of MIF in HCC, we employed the transwell invasion chamber to study the effect of MIF on tumor cell migration. Our results showed that recombinant MIF and the supernatants of tumor cell line culture could enhance the invasion and migration of HCC cells. This effect can be inhibited by the addition of a neutralizing anti-MIF antibody. We observed that increased MIF serum levels correlated with higher levels of interleukin-8 (IL-8) in the sera of patients with HCC than in normal volunteers. We therefore hypothesized that MIF may regulate the production of angiogenic factors by HCC cells. To test this hypothesis, we examined the effect of MIF treatment on vascular endothelial growth factor (VEGF) and IL-8 expression by HCC cell lines. MIF induced a significant dose-dependent increase in IL-8 and VEGF production. Taken together, our results indicated that MIF may act as an autocrine-acting factor that stimulates angiogenesis and metastasis in HCC by promoting expression of angiogenic factors and migration of tumor cells. A more detailed understanding of the MIF regulatory mechanisms involved may provide insight into new direction in the treatment of HCC.