Further evidence for increased macrophage migration inhibitory factor expression in prostate cancer

The Tautomerase Activity of Tumor Exosomal MIF Promotes Pancreatic Cancer Progression by Modulating MDSC Differentiation

Pancreatic cancer is a deadly disease that is largely resistant to immunotherapy, in part because of the accumulation of immunosuppressive cells in the tumor microenvironment (TME). Much evidence suggests that tumor-derived exosomes (TDE) contribute to the immunosuppressive activity mediated by myeloid-derived suppressor cells (MDSC) within the pancreatic cancer TME. However, the underlying mechanisms remain elusive. Herein, we report that macrophage migration inhibitory factor (MIF) in TDEs has a key role in inducing MDSC formation in pancreatic cancer. We identified MIF in both human and murine pancreatic cancer-derived exosomes. Upon specific shRNA-mediated knockdown of MIF, the ability of pancreatic cancer-derived exosomes to promote MDSC differentiation was abrogated. This phenotype was rescued by reexpression of the wild-type form of MIF rather than a tautomerase-null mutant or a thiol-protein oxidoreductase-null mutant, indicating that both MIF enzyme activity sites play a role in exosome-induced MDSC formation in pancreatic cancer. RNA sequencing data indicated that MIF tautomerase regulated the expression of genes required for MDSC differentiation, recruitment, and activation. We therefore developed a MIF tautomerase inhibitor, IPG1576. The inhibitor effectively inhibited exosome-induced MDSC differentiation in vitro and reduced tumor growth in an orthotopic pancreatic cancer model, which was associated with decreased numbers of MDSCs and increased infiltration of CD8+ T cells in the TME. Collectively, our findings highlight a pivotal role for MIF in exosome-induced MDSC differentiation in pancreatic cancer and underscore the potential of MIF tautomerase inhibitors to reverse the immunosuppressive pancreatic cancer microenvironment, thereby augmenting anticancer immune responses.

Hallmarks of Cancer Affected by the MIF Cytokine Family

New diagnostic methods and treatments have significantly decreased the mortality rates of cancer patients, but further improvements are warranted based on the identification of novel tumor-promoting molecules that can serve as therapeutic targets. The macrophage migration inhibitory factor (MIF) family of cytokines, comprising MIF and DDT (also known as MIF2), are overexpressed in almost all cancer types, and their high expressions are related to a worse prognosis for the patients. MIF is involved in 9 of the 10 hallmarks of cancer, and its inhibition by antibodies, nanobodies, or small synthetic molecules has shown promising results. Even though DDT is also proposed to be involved in several of the hallmarks of cancer, the available information about its pro-tumoral role and mechanism of action is more limited. Here, we provide an overview of the involvement of both MIF and DDT in cancer, and we propose that blocking both cytokines is needed to obtain the maximum anti-tumor response.

Bone Marrow Macrophages Induce Inflammation by Efferocytosis of Apoptotic Prostate Cancer Cells via HIF-1α Stabilization

The clearance of apoptotic cancer cells by macrophages, known as efferocytosis, fuels the bone-metastatic growth of prostate cancer cells via pro-inflammatory and immunosuppressive processes. However, the exact molecular mechanisms remain unclear. In this study, single-cell transcriptomics of bone marrow (BM) macrophages undergoing efferocytosis of apoptotic prostate cancer cells revealed a significant enrichment in their cellular response to hypoxia. Here, we show that BM macrophage efferocytosis increased hypoxia inducible factor-1alpha (HIF-1α) and STAT3 phosphorylation (p-STAT3 at Tyr705) under normoxic conditions, while inhibitors of p-STAT3 reduced HIF-1α. Efferocytosis promoted HIF-1α stabilization, reduced its ubiquitination, and induced HIF-1α and p-STAT3 nuclear translocation. HIF-1α stabilization in efferocytic BM macrophages resulted in enhanced expression of pro-inflammatory cytokine MIF, whereas BM macrophages with inactive HIF-1α reduced MIF expression upon efferocytosis. Stabilization of HIF-1α using the HIF-prolyl-hydroxylase inhibitor, Roxadustat, enhanced MIF expression in BM macrophages. Furthermore, BM macrophages treated with recombinant MIF protein activated NF-κB (p65) signaling and increased the expression of pro-inflammatory cytokines. Altogether, these findings suggest that the clearance of apoptotic cancer cells by BM macrophages triggers p-STAT3/HIF-1α/MIF signaling to promote further inflammation in the bone tumor microenvironment where a significant number of apoptotic cancer cells are present.

Peripheral blood and tissue assessment highlights differential tumor-circulatory gradients of IL2 and MIF with prognostic significance in resectable pancreatic ductal adenocarcinoma

Various reports have pointed out the potential of cytokines as diagnostic and prognostic biomarkers for pancreatic ductal adenocarcinoma (PDA). Nonetheless, the evidence is contradictory and the role of chronic inflammation and relationship between circulatory and corresponding tumoral cytokine levels remain elusive. Utilizing a broad array of cytokines, we identified two opposing parameters: serum levels of interleukin 2 (IL2) and macrophage migration inhibitory factor (MIF) are diagnostic and prognostic factors. While low IL2 levels are associated with PDA, they also relate to a favorable prognosis of patients. In contrast, high MIF levels are associated with PDA and simultaneously related to an unfavorable outcome. MIF levels are associated with the intratumoral density of M2 macrophages (CD163⁺). Focusing on the tumor-to-serum gradient, we unveiled a different pattern of compartmental cytokine expression between IL2 and MIF. Our findings indicate that an extra-tumoral source of IL2 exists in PDA patients leading to increased detectability in the circulatory system. In case of MIF, the tumor microenvironment is presumably the main site of production and thereby reflected by serum measurements. Taken together, our study describes IL2 and MIF levels as biomarker candidates for diagnosis and prognosis of PDA, highlighting the need for compartmental cytokine analyses. From the perspective of tumor immunobiology, we identify multiple inflammatory states (proposed as types I-III) and see that systemic chronic dysregulation, independent of tumor microenvironment, can be measured and is a possible tool for stratification. Thus, direct correlation of local cytokine levels to peripheral blood levels needs to be regarded with caution.

Phase I study of imalumab (BAX69), a fully human recombinant antioxidized macrophage migration inhibitory factor antibody in advanced solid tumours

Aim

Preclinical evidence suggests that oxidized macrophage migration inhibitory factor (oxMIF) may be involved in carcinogenesis. This phase 1 study (NCT01765790) assessed the safety, tolerability, pharmacokinetics and antitumour activity of imalumab, an oxMIF inhibitor, in patients with advanced cancer using ‘3 + 3’ dose escalation.

Methods

In Schedule 1, patients with solid tumours received doses from 1 to 50 mg/kg IV every 2 weeks. In Schedule 2, patients with metastatic colorectal adenocarcinoma, non‐small‐cell lung, or ovarian cancer received weekly doses of 10 or 25 mg/kg IV (1 cycle = 28 days). Treatment continued until disease progression, unacceptable toxicity, dose‐limiting toxicity, or withdrawal of consent.

Results

Fifty of 68 enrolled patients received imalumab. The most common treatment‐related adverse events (TRAEs) included fatigue (10%) and vomiting (6%); four grade 3 serious TRAEs (two patients) occurred. The dose‐limiting toxicity was allergic alveolitis (one patient, 50 mg/kg every 2 weeks). The maximum tolerated and biologically active doses were 37.5 mg/kg every 2 weeks and 10 mg/kg weekly, respectively. Of 39 assessed patients, 13 had stable disease (≥4 months in 8 patients).

Conclusions

Imalumab had a maximum tolerated dose of 37.5 mg/kg every 2 weeks in patients with advanced solid tumours, with a biologically active dose of 10 mg/kg weekly. Further investigation will help define the role of oxMIF as a cancer treatment target.

MIF-173G/C (rs755622) polymorphism as a risk factor for acute lymphoblastic leukemia development in children

BACKGROUND

Macrophage inhibitory factor (MIF) is a pro-inflammatory cytokine modulating monocyte motility and a pleiotropic regulator of different biological and cellular processes. The MIF-173G/C (rs755622) polymorphism is found in the promoter region and affects its activity. The present study investigated the MIF polymorphism as a risk factor for the development of acute lymphoblastic leukemia (ALL) in Egyptian children.

METHODS

We analyzed the MIF-173G/C (rs755622) polymorphism in 180 ALL cases and 150 healthy control children by amplification of the gene using a polymerase chain reaction followed by restriction endonuclease digestion and running on an agarose gel for visualization of the product.

RESULTS

We found a significant incidence of the homozygous polymorphic (CC) genotype and the combined polymorphic genotypes (GC + CC) in ALL patients compared to healthy controls (p = 0.001 and p = 0.007, respectively), whereas the wild-type genotype (GG) was more common in healthy controls (p = 0.006). Multivariate logistic regression analysis adjustment for MIF different genotypes and other potential risk factors such as age, sex and parental smoking indicated that the CC genotype is the only significant risk factor for the test (p = 0.02). We also noted that, by increasing the C-allele representation within the gene [GC, CC], there was an increase in total leukocytic count (p = 0.09 and p = 0.001, respectively) that may reflect the bad prognostic impact of the polymorphic allele, although further studies are needed.

CONCLUSIONS

The results of the present study indicate that the MIF-173G/C (rs755622) polymorphism is a risk factor for childhood ALL development with respect to both homozygous and combined polymorphic genotypes. In addition, the increased leukocytic count in synchronization with the increased representation of the polymorphic C-allele may reflect its bad prognostic impact.

Oxidized macrophage migration inhibitory factor is a potential new tissue marker and drug target in cancer

Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine, which was shown to be upregulated in cancers and to exhibit tumor promoting properties. Unlike other cytokines, MIF is ubiquitously present in the circulation and tissue of healthy subjects. We recently described a previously unrecognized, disease-related isoform of MIF, designated oxMIF, which is present in the circulation of patients with different inflammatory diseases. In this article, we report that oxMIF is also linked to different solid tumors as it is specifically expressed in tumor tissue from patients with colorectal, pancreatic, ovarian and lung cancer. Furthermore, oxMIF can be specifically targeted by a subset of phage display-derived fully human, monoclonal anti-MIF antibodies (mAbs) that were shown to neutralize pro-tumorigenic activities of MIF in vivo. We further demonstrate that anti-oxMIF mAbs sensitize human cancer cell lines (LNCaP, PC3, A2780 and A2780ADR) to the action of cytotoxic drugs (mitoxantrone, cisplatin and doxorubicin) in vitro and in an A2780 xenograft mouse model of ovarian cancer. We conclude that oxMIF is the disease related isoform of MIF in solid tumors and a potential new diagnostic marker and drug target in cancer.

A computational assessment of the predicted structures of Human Macrophage Migration Inhibitory Factor 1 orthologs in parasites and its affinity to human CD74 receptor

The human macrophage migration inhibitory factor 1 (Hu-MIF-1) is a protein involved in the inflammatory and immunology response to parasite infection. In the present study, the existence of Hu-MIF-1 from parasites have been explored by mining WormBase. A total of 35 helminths were found to have Hu-MIF-1 homologs, including some parasites of importance for public health. Physicochemical, structural, and biological properties of Hu-MIF-1 were compared with its orthologs in parasites showing that most of these are secretory proteins, with positive net charge and presence of the Cys-Xaa-Xaa-Cys motif that is critical for its oxidoreductase activity. The inhibitor-binding site present in Hu-MIF-1 is well conserved among parasite MIFs suggesting that Hu-MIF inhibitors may target orthologs in pathogens. The binding of Hu-MIF-1 to its cognate receptor CD74 was predicted by computer-assisted docking, and it resulted to be very similar to the predicted complexes formed by parasite MIFs and human CD74. More than 1 plausible conformation of MIFs in the extracellular loops of CD74 may be possible as demonstrated by the different predicted conformations of MIF orthologs in complex with CD74. Parasite MIFs in complex with CD74 resulted with some charged residues oriented to CD74, which was not observed in the Hu-MIF-1/CD74 complex. Our findings predict the binding mode of Hu-MIF-1 and orthologs with CD74, which can assist in the design of novel MIF inhibitors. Whether the parasite MIFs function specifically subvert host immune responses to suit the parasite is an open question that needs to be further investigated. Future research should lead to a better understanding of parasite MIF action in the parasite biology.

Expression of CD74 in invasive breast carcinoma: its relation to Nottingham Prognostic Index, hormone receptors, and HER2 immunoprofile

PURPOSE

To study the immunohistochemical expression of CD74 in series of invasive breast carcinomas classified according to their estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) immunoprofile and explore its correlation to Nottingham Prognostic Index (NPI) and tumor pathologic stage to determine if it has a prognostic value.

METHODS

A total of 160 cases of mammary carcinoma were classified broadly according to their ER, PR, and HER2 expression into luminal, HER2-positive, and triple-negative groups. The NPI was calculated and pathologic stage was recorded for each individual case and cases were classified into different prognostic groups. The CD74 expression was evaluated immunohistochemically and correlated to different prognostic variables.

RESULTS

The CD74 immunohistochemical expression in invasive breast carcinoma was significantly higher in triple-negative tumors, higher tumor grades, presence of lymph nodal metastasis, higher tumor stages, and higher NPI scores.

CONCLUSIONS

The CD74 might be a useful prognostic indicator predicting poor outcome of patients with breast carcinoma. Its consistent expression in triple-negative breast carcinomas points to the need of further studies to test the possibility if it can be targeted in treatment of breast carcinoma, especially in such groups.

Macrophage migration inhibitory factor interacts with thioredoxin-interacting protein and induces NF-κB activity

The nuclear factor kappa B (NF-κB) pathway is pivotal in controlling survival and apoptosis of cancer cells. Macrophage migration inhibitory factor (MIF), a cytokine that regulates the immune response and tumorigenesis under inflammatory conditions, is upregulated in various tumors. However, the intracellular functions of MIF are unclear. In this study, we found that MIF directly interacted with thioredoxin-interacting protein (TXNIP), a tumor suppressor and known inhibitor of NF-κB activity, and MIF significantly induced NF-κB activation. MIF competed with TXNIP for NF-κB activation, and the intracellular MIF induced NF-κB target genes, including c-IAP2, Bcl-xL, ICAM-1, MMP2 and uPA, by inhibiting the interactions between TXNIP and HDACs or p65. Furthermore, we identified the interaction motifs between MIF and TXNIP via site-directed mutagenesis of their cysteine (Cys) residues. Cys⁵⁷ and Cys⁸¹ of MIF and Cys³⁶ and Cys¹²⁰ of TXNIP were responsible for the interaction. MIF reversed the TXNIP-induced suppression of cell proliferation and migration. Overall, we suggest that MIF induces NF-κB activity by counter acting the inhibitory effect of TXNIP on the NF-κB pathway via direct interaction with TXNIP. These findings reveal a novel intracellular function of MIF in the progression of cancer.

MIF, a controversial cytokine: a review of structural features, challenges, and opportunities for drug development

INTRODUCTION

Macrophage migration inhibitory factor (MIF) has emerged as a promising drug target in diseases including sepsis, rheumatoid arthritis, and cancer. MIF has multiple properties that favor development of specific, targeted therapies: it is expressed broadly among human cells, has noted roles in diverse inflammatory and oncological processes, and has intrinsic enzymatic activity amenable to high-throughput screening. Despite these advantages, anti-MIF therapy remains well behind other cytokine-targeted therapeutics, with no small molecules in the pipeline for clinical development and anti-MIF antibodies only recently beginning clinical trials. Areas covered: In this review we summarize current literature regarding MIF structure and function-including challenges and controversies that have arisen in studies of anti-MIF therapeutics-and propose a strategy for development of clinically relevant anti-MIF drugs. Expert opinion: We believe that the field of anti-MIF therapeutics would benefit from capitalizing on the protein's multiple assets while acknowledging their flaws. The tautomerase enzymatic site of MIF may not be active biologically, but can nonetheless offer a high-throughput method to highlight molecules of interest that can affect its other, frequently intertwined bioactivities. Future work should also focus on developing more robust assays for MIF bioactivity that can be used for second-pass screening and specificity studies.

Contribution of Macrophage Migration Inhibitory Factor -173G/C Gene Polymorphism to the Risk of Cancer in Chinese Population

BACKGROUND

Macrophage migration inhibitory factor (MIF) -173G/C (rs755622) gene polymorphism has been associated with cancer risk. Previous studies have revealed that MIF -173G/C gene polymorphism may increase cancer in the Chinese population, while results of individual published studies remain inconsistent and inconclusive.We performed this meta-analysis to derive a more precise estimation of the relationship.

MATERIALS AND METHODS

We conducted a search on PubMed, Embase, MEDLINE, Cochrane Library ,Chinese National Knowledge Infrastructure (CNKI), Wanfang, Weipu on Dec 31, 2014.Odds ratio (OR) and 95% confidence interval (95% CI) were used to assess the association. A total of eight studies including 2,186 cases and 2,285 controls were involved in this meta-analysis.

RESULTS

The pooled results indicated the significant association between MIF -173G/C polymorphism and the risk of cancer for Chinese population (CC + CG vs GG: OR=1.14, 95%CI=1.02-127, pheterogeneity<0.01; P =0.023; CC vs CG+GG: OR=1.12, 95%CI=1.02- 1.23, pheterogeneity< 001; P =0.017;CC vs GG: OR=1.18, 95%CI=1.04-1.33, pheterogeneity<001; P =0.008; CG vs GG:OR=1.03, 95%CI=0.91-1.15, pheterogeneity<001; P =0.656; C vs G:OR=1.24, 95%CI=1.14-1.25, pheterogeneity<001; P <001). Subgroup analysis showed that in patients with "solid tumors", heterogeneity was very large (OR=0.94,95%CI=0.83-1.06,pheterogeneity=0.044; p=0.297). Within "non-solid tumors", the association became even stronger (OR=6.62, 95 % CI=4.32-10.14, pheterogeneity<0.001; p <0.001).

CONCLUSIONS

This study suggested that MIF ?173G/C gene polymorphism may increase increase cancer in the Chinese population.Furthermore, more larger sample and representative population-based casees and well-matched controls are needed to validate our results.

MIF Maintains the Tumorigenic Capacity of Brain Tumor-Initiating Cells by Directly Inhibiting p53

Tumor-initiating cells thought to drive brain cancer are embedded in a complex heterogeneous histology. In this study, we isolated primary cells from 21 human brain tumor specimens to establish cell lines with high tumorigenic potential and to identify the molecules enabling this capability. The morphology, sphere-forming ability upon expansion, and differentiation potential of all cell lines were indistinguishable in vitro However, testing for tumorigenicity revealed two distinct cell types, brain tumor-initiating cells (BTIC) and non-BTIC. We found that macrophage migration inhibitory factor (MIF) was highly expressed in BTIC compared with non-BTIC. MIF bound directly to both wild-type and mutant p53 but regulated p53-dependent cell growth by different mechanisms, depending on glioma cell line and p53 status. MIF physically interacted with wild-type p53 in the nucleus and inhibited its transcription-dependent functions. In contrast, MIF bound to mutant p53 in the cytoplasm and abrogated transcription-independent induction of apoptosis. Furthermore, MIF knockdown inhibited BTIC-induced tumor formation in a mouse xenograft model, leading to increased overall survival. Collectively, our findings suggest that MIF regulates BTIC function through direct, intracellular inhibition of p53, shedding light on the molecular mechanisms underlying the tumorigenicity of certain malignant brain cells. Cancer Res; 76(9); 2813-23. ©2016 AACR.

Mass Spectrometric Immunoassay for the qualitative and quantitative analysis of the cytokine Macrophage Migration Inhibitory Factor (MIF)

Background

The cytokine MIF (Macrophage Migration Inhibitory Factor) has diverse physiological roles and is present at elevated concentrations in numerous disease states. However, its molecular heterogeneity has not been previously investigated in biological samples. Mass Spectrometric Immunoassay (MSIA) may help elucidate MIF post-translational modifications existing in vivo and provide additional clarity regarding its relationship to diverse pathologies.

Results

In this work, we have developed and validated a fully quantitative MSIA assay for MIF, and used it in the discovery and quantification of different proteoforms of MIF in serum samples, including cysteinylated and glycated MIF. The MSIA assay had a linear range of 1.56-50 ng/mL, and exhibited good precision, linearity, and recovery characteristics. The new assay was applied to a small cohort of human serum samples, and benchmarked against an MIF ELISA assay.

Conclusions

The quantitative MIF MSIA assay provides a sensitive, precise and high throughput method to delineate and quantify MIF proteoforms in biological samples.

CD74 interferes with the expression of fas receptor on the surface of lymphoma cells

BACKGROUND

Resistance to Fas-mediated apoptosis limits the efficacy of currently available chemotherapy regimens. We identified CD74, which is known to be overexpressed in hematological malignancies, as one of the factors interfering with Fas-mediated apoptosis.

METHODS

CD74 expression was suppressed in human B-lymphoma cell lines, BJAB and Raji, by either transduction with lentivirus particles or transfection with episomal vector, both encoding CD74-specific shRNAs or non-target shRNA. Effect of CD74 expression on Fas signaling was evaluated by comparing survival of mice hydrodynamically transfected with vector encoding full-length CD74 or empty vector. Sensitivity of cells with suppressed CD74 expression to FasL, edelfosine, doxorubicin, and a humanized CD74-specific antibody, milatuzumab, was evaluated by flow cytometry and compared to control cells. Fas signaling in response to FasL stimulation and the expression of Fas signaling components were evaluated by Western blot. Surface expression of Fas was detected by flow cytometry.

RESULTS

We determined that cells with suppressed CD74 are more sensitive to FasL-induced apoptosis and Fas signaling-dependent chemotherapies, edelfosine and doxorubicin, than control CD74-expressing cells. On the other hand, expression of full-length CD74 in livers protected the mice from a lethal challenge with agonistic anti-Fas antibody Jo2. A detailed analysis of Fas signaling in cells lacking CD74 and control cells revealed increased cleavage/activation of pro-caspase-8 and corresponding enhancement of caspase-3 activation in the absence of CD74, suggesting that CD74 affects the immediate early steps in Fas signaling at the plasma membrane. Cells with suppressed CD74 expression showed increased staining of Fas receptor on their surface. Pre-treatment with milatuzumab sensitized BJAB cells to Fas-mediated apoptosis.

CONCLUSION

We anticipate that specific targeting of the CD74 on the cell surface will sensitize CD74-expressing cancer cells to Fas-mediated apoptosis, and thus will increase effectiveness of chemotherapy regimens for hematological malignancies.

Targeting the heat shock protein 90: a rational way to inhibit macrophage migration inhibitory factor function in cancer

PURPOSE OF REVIEW

Macrophage migration inhibitory factor (MIF), originally identified as a proinflammatory cytokine, is highly elevated in many human cancer types, independent of their histological origin. MIF's tumour promoting activities correlate with tumour aggressiveness and poor clinical prognosis. Genetic depletion of MIF in mouse cancer models results in significant inhibition of cell proliferation and induction of apoptosis, making it an attractive target for anticancer therapies. Here, we summarize the current possibilities to inhibit MIF function in cancer.

RECENT FINDINGS

All known small molecule MIF inhibitors antagonize MIF's enzymatic function. However, a recent knockin mouse model suggested that protein interactions play a bigger biological role in tumour cell growth regulation than MIF's enzymatic activity. Thus, alternative strategies are important for targeting MIF. Recently, we identified that MIF in cancer cells is highly stabilized through the heat shock protein 90 machinery (HSP90). Thus, MIF is an HSP90 client. Pharmacological inhibition of the Hsp90 ATPase activity results in MIF degradation in several types of cancer cells. This provides a new way to inhibit MIF function independent of its enzymatic activity.

SUMMARY

Targeting the HSP90 machinery is a promising way to inhibit MIF function in cancer. Along with MIF and dependent on the molecular make-up of the tumour, a large number of other critical tumourigenic proteins are also destabilized by HSP90 inhibition, overall resulting in a profound block of tumour growth.

Involvement of macrophage migration inhibitory factor and its receptor (CD74) in human breast cancer

Macrophage migration inhibitory factor (MIF) and its receptor CD74 appear to be involved in tumorigenesis. We evaluated, by immunohistochemical staining, the tissue expression and distribution of MIF and CD74 in serial sections of human invasive breast cancer tumor specimens. The serum MIF level was also determined in breast cancer patients. We showed a significant increase in serum MIF average levels in breast cancer patients compared to healthy individuals. MIF tissue expression, quantified by a modified Allred score, was strongly increased in carcinoma compared to tumor-free specimens, in the cancer cells and in the peritumoral stroma, with fibroblasts the most intensely stained. We did not find any significant correlation with histoprognostic factors, except for a significant inverse correlation between tumor size and MIF stromal positivity. CD74 staining was heterogeneous and significantly decreased in cancer cells but increased in the surrounding stroma, namely in lymphocytes, macrophages and vessel endothelium. There was no significant variation according to classical histoprognostic factors, except that CD74 stromal expression was significantly correlated with triple-negative receptor (TRN) status and the absence of estrogen receptors. In conclusion, our data support the concept of a functional role of MIF in human breast cancer. In addition to auto- and paracrine effects on cancer cells, MIF could contribute to shape the tumor microenvironment leading to immunomodulation and angiogenesis. Interfering with MIF effects in breast tumors in a therapeutic perspective remains an attractive but complex challenge. Level of co-expression of MIF and CD74 could be a surrogate marker for efficacy of anti-angiogenic drugs, particularly in TRN breast cancer tumor.

Trichomonas vaginalis homolog of macrophage migration inhibitory factor induces prostate cell growth, invasiveness, and inflammatory responses

The human-infective parasite Trichomonas vaginalis causes the most prevalent nonviral sexually transmitted infection worldwide. Infections in men may result in colonization of the prostate and are correlated with increased risk of aggressive prostate cancer. We have found that T. vaginalis secretes a protein, T. vaginalis macrophage migration inhibitory factor (TvMIF), that is 47% similar to human macrophage migration inhibitory factor (HuMIF), a proinflammatory cytokine. Because HuMIF is reported to be elevated in prostate cancer and inflammation plays an important role in the initiation and progression of cancers, we have explored a role for TvMIF in prostate cancer. Here, we show that TvMIF has tautomerase activity, inhibits macrophage migration, and is proinflammatory. We also demonstrate that TvMIF binds the human CD74 MIF receptor with high affinity, comparable to that of HuMIF, which triggers activation of ERK, Akt, and Bcl-2-associated death promoter phosphorylation at a physiologically relevant concentration (1 ng/mL, 80 pM). TvMIF increases the in vitro growth and invasion through Matrigel of benign and prostate cancer cells. Sera from patients infected with T. vaginalis are reactive to TvMIF, especially in males. The presence of anti-TvMIF antibodies indicates that TvMIF is released by the parasite and elicits host immune responses during infection. Together, these data indicate that chronic T. vaginalis infections may result in TvMIF-driven inflammation and cell proliferation, thus triggering pathways that contribute to the promotion and progression of prostate cancer.

CD74: a new prognostic factor for patients with malignant pleural mesothelioma

Background:

The pro-inflammatory cytokine migration inhibitory factor (MIF) and its receptor CD74 have been proposed as possible therapeutic targets in several cancers. We studied the expression of MIF and CD74 together with calretinin in specimens of malignant pleural mesothelioma (MPM), correlating their expression levels with clinico-pathologic parameters, in particular overall survival (OS).

Methods:

Migration inhibitory factor, CD74, and calretinin immunoreactivity were investigated in a tissue microarray of 352 patients diagnosed with MPM. Protein expression intensities were semiquantitatively scored in the tumour cells and in the peritumoral stroma. Markers were matched with OS, age, gender, and histological subtype.

Results:

Clinical data from 135 patients were available. Tumour cell expressions of MIF and CD74 were observed in 95% and 98% of MPM specimens, respectively, with a homogenous distribution between the different histotypes. CD74 (P<0.001) but not MIF overexpression (P=0.231) emerged as an independent prognostic factor for prolonged OS. High expression of tumour cell calretinin correlated with the epithelioid histotype and was also predictive of longer OS (P<0.001). When compared with previously characterised putative epithelial-to-mesenchymal transition markers, CD74 correlated positively with tumoral PTEN and podoplanin expressions, but was inversely related with periostin expression.

Conclusions:

High expression of CD74 is an independent prognostic factor for prolonged OS in mesothelioma patients.

Macrophage migration inhibitory factor regulates AKT signaling in hypoxic culture to modulate senescence of human mesenchymal stem cells

Hypoxic culture has been shown to delay premature senescence occurring during in vitro culture. Human mesenchymal stem cells (hMSCs) cultured under hypoxia have been reported to maintain their stemness properties and delay senescence compared to the cells cultured under normoxia. However, the molecular mechanism by which hypoxia regulates premature senescence has not been fully revealed. In this study, hMSCs were cultured under the conditions of 21% (normoxia) and 1% O2 (hypoxia) tension and analyzed for cell growth, expression of MSC surface markers, multilineage differentiation, and cellular senescence. Our results showed that more cells retained MSC surface markers in hypoxic culture than those in normoxic culture, and hypoxia was able to enhance multilineage differentiation of hMSCs. The hypoxic condition also delayed cellular senescence of hMSCs, increased activation of AKT signaling, and upregulated both intra- and extracellular levels of macrophage migration inhibitory factor (MIF) compared to the normoxic condition. Inhibition of AKT activity in hypoxic culture increased the number of cells with positive staining for senescence-associated β-galactosidase activity, upregulated expression levels of senescence-associated markers p16 and p21 mRNA transcripts, and decreased expression levels of potency-associated markers, including NANOG, OCT3/4, and SOX2. On the other hand, upregulated intra- and extracellular levels of MIF by stable MIF overexpression in normoxic culture increased the activation of AKT while decreasing mRNA expression of senescence-associated markers and increasing expression of potency-associated markers. Taken together, our findings suggest that hMSCs in hypoxic culture produce endogenous MIF to activate AKT signaling to delay the progression of cellular senescence.

Human anti-macrophage migration inhibitory factor antibodies inhibit growth of human prostate cancer cells in vitro and in vivo

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine, originally discovered for its eponymous effect and now known for pleiotropic biologic properties in immunology and oncology. Circulating MIF levels are elevated in several types of human cancer including prostate cancer. MIF is released presumably by both stromal and tumor cells and enhances malignant growth and metastasis by diverse mechanisms, such as stimulating tumor cell proliferation, suppressing apoptotic death, facilitating invasion of the extracellular matrix, and promoting angiogenesis. Recently described fully human anti-MIF antibodies were tested in vitro and in vivo for their ability to influence growth rate and invasion of the human PC3 prostate cancer cell line. In vitro, the selected candidate antibodies BaxG03, BaxB01, and BaxM159 reduced cell growth and viability by inhibiting MIF-induced phosphorylation of the central kinases p44/42 mitogen-activated protein kinase [extracellular signal-regulated kinase-1 and -2 (ERK1/2)] and protein kinase B (AKT). Incubation of cells in the presence of the antibodies also promoted activation of caspase-3/7. The antibodies furthermore inhibited MIF-promoted invasion and chemotaxis as transmigration through Matrigel along a MIF gradient was impaired. In vivo, pharmacokinetic parameters (half-life, volume of distribution, and bioavailability) of the antibodies were determined and a proof-of-concept was obtained in a PC3-xenograft mouse model. Treatment with human anti-MIF antibodies blunted xenograft tumor growth in a dose-dependent manner. We therefore conclude that the anti-MIF antibodies described neutralize some of the key tumor-promoting activities of MIF and thus limit tumor growth in vivo.

Release of macrophage migration inhibitory factor by neuroendocrine-differentiated LNCaP cells sustains the proliferation and survival of prostate cancer cells

The acquisition of neuroendocrine (NE) characteristics by prostate cancer (PCa) cells is closely related to tumour progression and hormone resistance. The mechanisms by which NE cells influence PCa growth and progression are not fully understood. Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine involved in oncogenic processes, and MIF serum levels correlate with aggressiveness of PCa. Here, we investigated the regulation and the functional consequences of MIF expression during NE transdifferentiation of PCa cells. NE differentiation (NED) of LNCaP cells, initiated either by increasing intracellular levels of cAMP or by culturing cells in an androgen-depleted medium, was associated with markedly increased MIF release. Yet, intracellular MIF protein and mRNA levels and MIF gene promoter activity decreased during NED of LNCaP cells, suggesting that NED favours MIF release despite decreasing MIF synthesis. Adenoviral-mediated forced MIF expression in NE-differentiated LNCaP cells increased cell proliferation without affecting the expression of NE markers. Addition of exogenous recombinant MIF to LNCaP and PC-3 cells stimulated the AKT and ERK1/2 signalling pathways, the expression of genes involved in PCa, as well as proliferation and resistance to paclitaxel and thapsigargin-induced apoptosis. Altogether, these data provide evidence that increased MIF release during NED in PCa may facilitate cancer progression or recurrence, especially following androgen deprivation. Thus, MIF could represent an attractive target for PCa therapy.

A bead-based multiplexed immunoassay to evaluate breast cancer biomarkers for early detection in pre-diagnostic serum

This study investigates whether a set of ten potential breast cancer serum biomarkers and cancer antigens (osteopontin (OPN), haptoglobin, cancer antigen 15-3 (CA15-3), carcinoembryonic antigen (CEA), cancer antigen 125 (CA-125), prolactin, cancer antigen 19-9 (CA19-9), α-fetoprotein (AFP), leptin and migration inhibitory factor (MIF)) can predict early stage breast cancer in samples collected before clinical diagnosis (phase III samples). We performed a nested case-control study within the Prospect-EPIC (European Prospective Investigation into Cancer and nutrition) cohort. We examined to what extent the biomarker panel could discriminate between 68 women diagnosed with breast cancer up to three years after enrollment and 68 matched healthy controls (all 56-64 years at baseline). Using a quantitative bead-based multiplexed assay, we determined protein concentrations in serum samples collected at enrollment. Principal Component Analysis (PCA) and Random Forest (RF) analysis revealed that on the basis of all ten proteins, early cases could not be separated from controls. When we combined serum protein concentrations and subject characteristics related to breast cancer risk in the RF analysis, this did not result in classification accuracy scores that could correctly classify the samples (sensitivity: 50%, specificity: 50%). Our findings indicate that this panel of selected tumor markers cannot be used for diagnosis of early breast cancer.

Dual-targeting immunotherapy of lymphoma: potent cytotoxicity of anti-CD20/CD74 bispecific antibodies in mantle cell and other lymphomas

We describe the use of novel bispecific hexavalent Abs (HexAbs) to enhance anticancer immunotherapy. Two bispecific HexAbs [IgG-(Fab)4 constructed from veltuzumab (anti-CD20 IgG) and milatuzumab (anti-CD74 IgG)] show enhanced cytotoxicity in mantle cell lymphoma (MCL) and other lymphoma/leukemia cell lines, as well as patient tumor samples, without a crosslinking Ab, compared with their parental mAb counterparts, alone or in combination. The bispecific HexAbs have different properties from and are more potent than their parental mAbs in vitro. The juxtaposition of CD20 and CD74 on MCL cells by the HexAbs resulted in homotypic adhesion and triggered intracellular changes that include loss of mitochondrial transmembrane potential, production of reactive oxygen species, rapid and sustained phosphorylation of ERKs and JNK, down-regulation of pAkt and Bcl-xL, actin reorganization, and lysosomal membrane permeabilization, culminating in cell death. They also displayed different potencies in depleting lymphoma cells and normal B cells from whole blood ex vivo and significantly extended the survival of nude mice bearing MCL xenografts in a dose-dependent manner, thus indicating stability and antitumor activity in vivo. Such bispecific HexAbs may constitute a new class of therapeutic agents for improved cancer immunotherapy, as shown here for MCL and other CD20+/CD74+ malignancies.

Association between macrophage migration inhibitory factor promoter region polymorphism (-173 G/C) and cancer: a meta-analysis

Background

Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine upstream of many inflammatory cytokines. MIF is implicated in several acute and chronic inflammatory conditions. MIF's promoter region has functional single nucleotide polymorphisms that controls MIF expression and protein levels. Since increased plasma MIF levels are associated with cancer, studies have examined the association between Mif promoter polymorphisms and cancer. This study is a meta-analysis of the available studies on such an association.

Results

A total of 5 studies were included in this meta-analysis to include 1116 cases (cancer patients) and 1728 controls (no cancer). Carrying any C allele in the Mif -173 G/C promoter polymorphism resulted in a significantly greater risk for developing cancer [OR = 1.89 (1.15-3.11), p = 0.012)] when compared to the (G/G) genotype. Subgroup analysis revealed that this association was significant only for "solid" tumors (including gastric and prostate cancers) [OR = 2.67 (1.26-5.65), p = 0.010] but not for "non-solid" tumors (leukemia) [OR = 1.21 (0.95-1.55), p = 0.122]. Furthermore, when only prostate tumor studies were included in the analysis, the association became even stronger [OR = 3.72 (2.55-5.41), p < 0.0001].

Conclusions

Meta-analysis suggests there is an association between any C allele in the Mif -173 G/C promoter polymorphism and an increased risk of cancer, particularly for solid tumors. The association appeared stronger for prostate cancer, specifically. Future studies that include different types of cancers are needed to support and extend these observations.

Natriuretic peptide receptor a as a novel target for prostate cancer

BACKGROUND

The receptor for the cardiac hormone atrial natriuretic peptide (ANP), natriuretic peptide receptor A (NPRA), is expressed in cancer cells, and natriuretic peptides have been implicated in cancers. However, the direct role of NPRA signaling in prostate cancer remains unclear.

RESULTS

NPRA expression was examined by western blotting, RT-PCR and immunohistochemistry. NPRA was downregulated by transfection of siRNA, shRNA and NPRA inhibitor (iNPRA). Antitumor efficacy of iNPRA was tested in mice using a TRAMP-C1 xenograft. Here, we demonstrated that NPRA is abundantly expressed on tumorigenic mouse and human prostate cells, but not in nontumorigenic prostate epithelial cells. NPRA expression showed positive correlation with clinical staging in a human PCa tissue microarray. Down-regulation of NPRA by siNPRA or iNPRA induced apoptosis in PCa cells. The mechanism of iNPRA-induced anti-PCa effects was linked to NPRA-induced expression of macrophage migration inhibitory factor (MIF), a proinflammatory cytokine over-expressed in PCa and significantly reduced by siNPRA. Prostate tumor cells implanted in mice deficient in atrial natriuretic peptide receptor A (NPRA-KO) failed to grow, and treatment of TRAMP-C1 xenografts with iNPRA reduced tumor burden and MIF expression. Using the TRAMP spontaneous PCa model, we found that NPRA expression correlated with MIF expression during PCa progression.

CONCLUSIONS

Collectively, these results suggest that NPRA promotes PCa development in part by regulating MIF. Our findings also suggest that NPRA is a potential prognostic marker and a target for PCa therapy.

CD74: an emerging opportunity as a therapeutic target in cancer and autoimmune disease

INTRODUCTION

CD74, also known as the invariant chain, participates in several key processes of the immune system, including antigen presentation, B-cell differentiation and inflammatory signaling. Despite being described more than 3 decades ago, new functions and novel interactions for this evolutionarily conserved molecule are still being unraveled. As a participant in several immunological processes and an indicator of disease in some conditions, it has potential as a therapeutic target.

AREAS COVERED

The relationship between the structure of CD74 variants and their physiological functions is detailed in this review. The function of CD74 in several cell lineages is examined with a focus on the interactions with cathepsins and, in an inflammatory milieu, the pro-inflammatory cytokine macrophage migratory inhibitory factor. The role of CD74 signaling in inflammatory and carcinogenic processes is outlined as is the use of CD74 as a therapeutic target (in cancer) and tool (as a vaccine).

EXPERT OPINION

CD74 has several roles within the cell and throughout the immune system. Most prominent amongst these are the complex relationships with MIF and cathepsins. Modulation of CD74 function shows promise for the effective amelioration of disease.

Macrophage migration inhibitory factor (MIF): a promising biomarker

Macrophage migration inhibitory factor (MIF) is an immunoregulatory cytokine, the effect of which on arresting random immune cell movement was recognized several decades ago. Despite its historic name, MIF also has a direct chemokine-like function and promotes cell recruitment. Multiple clinical studies have indicated the utility of MIF as a biomarker for different diseases that have an inflammatory component; these include systemic infections and sepsis, autoimmune diseases, cancer, and metabolic disorders such as type 2 diabetes and obesity. The identification of functional promoter polymorphisms in the MIF gene (MIF) and their association with the susceptibility or severity of different diseases has not only served to validate MIF's role in disease development but also opened the possibility of using MIF genotype information to better predict risk and outcome. In this article, we review the clinical data of MIF and discuss its potential as a biomarker for different disease applications.

Plasma concentration of malaria parasite-derived macrophage migration inhibitory factor in uncomplicated malaria patients correlates with parasitemia and disease severity

Host macrophage migration inhibitory factor (MIF) has been implicated in the pathogenesis of malaria infections. Several Plasmodium parasite-derived MIFs were identified to have the potential to regulate host immune response. However, the role of Plasmodium MIFs in the immunopathogenesis of malaria infection and the relationships between these mediators and inflammatory cytokines remained unclear. In this study, we have investigated two Plasmodium MIFs in peripheral blood of uncomplicated malaria patients and analyzed their correlations with several major factors during malaria infection. We found that both Plasmodium falciparum MIF (PfMIF) and Plasmodium vivax MIF (PvMIF) levels in patients were positively correlated with parasitemia, tumor necrosis factor alpha, interleukin-10 (IL-10), and monocyte chemoattractant protein 1 but were not correlated with transforming growth factor β1 and IL-12. Of interest was that the PvMIF level was positively correlated with host body temperature and human MIF (HuMIF) concentrations. Moreover, multiple stepwise regression analysis also showed that parasitemia, IL-10, and HuMIF expression were significant predictors of Plasmodium MIF production. In addition, during antimalarial drug treatment, the decreasing of Plasmodium MIF concentrations was followed by parasitemia in most patients. Our results suggested that the Plasmodium MIF circulating level reflects the level of parasitemia and thus was closely correlated with disease severity in uncomplicated malaria. Therefore, this factor has the potential to be a promising disease predictor and is applicable in clinical diagnosis.

Macrophage migration inhibitory factor plays a pivotal role in hepatocellular carcinoma and may be a noninvasive imaging target

Macrophage migration inhibitory factor (MIF) has emerged to play a central role in the control of the host inflammatory and immune response. Several reports have documented that MIF can inactivate the tumor suppresser activity of p53; overexpression of MIF was significantly higher in both the sera and the local lesions from patients with HCC than from patients with normal controls. These findings indicate that MIF may contribute to multiple aspects of tumor progression and neoplasia, thus MIF may be an effective therapeutic target molecule. We speculate that MIF is important for the development and progression of hepatocellular carcinoma, and can be used as a marker for tumor detection.

The MIF -173G/C polymorphism and risk of childhood acute lymphoblastic leukemia in a Chinese population

Migration inhibitory factor (MIF) has recently been defined as a novel pro-tumorigenic factor that promotes cell proliferation, migration, and invasion. The MIF -173C allele results in increased MIF promoter activity and is associated with a higher serum MIF level. We hypothesized that this polymorphism may contribute to childhood acute lymphoblastic leukemia (ALL) susceptibility. We genotyped the MIF -173G/C polymorphism (rs755622) in 346 ALL cases and 516 cancer-free controls in a Chinese population and found that the variant genotype GC and the combined genotypes GC/CC were associated with a significantly higher risk of childhood ALL [adjusted odds ratio (OR)=1.39, 95% confidence interval (CI)=1.01-1.93 for GC and adjusted OR=1.38, 95% CI=1.01-1.89 for GC/CC]. In addition, we found that the increased risk was more pronounced among high-risk ALL and B-phenotype ALL patients. Our results suggest that the MIF -173G/C polymorphism is involved in the etiology of childhood ALL and is a potential candidate gene for determining cancer susceptibility. Further validations in other populations are warranted.

Milatuzumab - a promising new immunotherapeutic agent

Milatuzumab is a new immunotherapeutic agent targeting CD74, a membrane protein preferentially expressed in hematopoietic cancers and some solid tumors. Broad expression and fast internalization makes CD74 an ideal target for cancer therapy. We reviewed published articles about CD74 and milatuzumab. We present a comprehensive review of CD74 functions and provide explanation of milatuzumab antitumor effects. This review describes CD74 protein biology with the emphasis on the role of CD74 in tumor survival and its new role in regulation of the Fas death receptor. The development of CD74 targeting therapies to induce tumor regression and cancer cell apoptosis is described and results of clinical trials are discussed. Milatuzumab shows selective binding and rapid internalization into CD74-positive cancer cells. Milatuzumab with and without conjugated toxins synergizes with other chemotherapeutic agents and elicits significant antitumor effects in mice. In a Phase I trial, milatuzumab showed no severe adverse effects in patients with relapsed/refractory multiple myeloma and it stabilized the disease in some patients for up to 12 weeks. Ongoing trials testing different treatment schedules of milatuzumab in chronic lymphocytic leukemia, non-Hodgkin's lymphoma and multiple myeloma indicate that milatuzumab shows no severe adverse effects in humans.

Structural and functional comparison of MIF ortholog from Plasmodium yoelii with MIF from its rodent host

Host-derived macrophage migration inhibitory factor (MIF) has been implicated in the pathogenesis of malaria infection, especially in malarial anemia. Although two Plasmodium parasite-derived MIF orthologs, Plasmodium falciparum MIF and P. berghei MIF were identified recently, the crystal structure and the precise roles of Plasmodium-derived MIFs, particularly in combination with the host MIF, remain unknown. In this study, we identified another MIF ortholog from a rodent-specific P. yoelii (PyMIF). This molecule shares a conserved three-dimensional structure with murine MIF (MmMIF), but with a different substrate binding pattern and much lower tautomerase activity. It could activate host cells via several signaling pathways in vitro, and inhibiting macrophage apoptosis, also similarly to MmMIF. However, we found that PyMIF and MmMIF acted synergistically to activate the MAPK-ERK1/2 signaling pathway at very low concentration but acted antagonistically at higher concentration. Furthermore, we detected PyMIF in the sera of infected mice and found that injection of recombinant PyMIF (rPyMIF) during infection could up-regulate several pro-inflammatory cytokines in vivo and slightly delay the death of infected mice. These data suggest that PyMIF modulates host immune responses together with host MIF and has potential to prolong parasitemia or the chronicity of malaria infection.

Macrophage migration inhibitory factor anti-thrombin III complexes are decreased in bladder cancer patient serum: Complex formation as a mechanism of inactivation

Mounting evidence suggests that the pro-inflammatory cytokine macrophage migration inhibitory factor (MIF) may serve as an important link between chronic inflammation and carcinogenesis as evidenced by the increase in serum MIF found in patients with various cancers. The present study identifies anti-thrombin III (ATIII) as an endogenous MIF binding protein, which reduces MIF biological activity. Serum MIF in bladder cancer patients (TCC stage II, n=50) was increased when compared to normal patients (n=50), while ATIII-MIF complexes were decreased in bladder cancer patient serum. These data suggest that increased circulating levels of bioactive MIF are present in bladder cancer patient serum.

SubpathwayMiner: a software package for flexible identification of pathways

With the development of high-throughput experimental techniques such as microarray, mass spectrometry and large-scale mutagenesis, there is an increasing need to automatically annotate gene sets and identify the involved pathways. Although many pathway analysis tools are developed, new tools are still needed to meet the requirements for flexible or advanced analysis purpose. Here, we developed an R-based software package (SubpathwayMiner) for flexible pathway identification. SubpathwayMiner facilitates sub-pathway identification of metabolic pathways by using pathway structure information. Additionally, SubpathwayMiner also provides more flexibility in annotating gene sets and identifying the involved pathways (entire pathways and sub-pathways): (i) SubpathwayMiner is able to provide the most up-to-date pathway analysis results for users; (ii) SubpathwayMiner supports multiple species (∼100 eukaryotes, 714 bacteria and 52 Archaea) and different gene identifiers (Entrez Gene IDs, NCBI-gi IDs, UniProt IDs, PDB IDs, etc.) in the KEGG GENE database; (iii) the system is quite efficient in cooperating with other R-based tools in biology. SubpathwayMiner is freely available at http://cran.r-project.org/web/packages/SubpathwayMiner/.

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.

Inhibition of MIF leads to cell cycle arrest and apoptosis in pancreatic cancer cells

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is the eighth most common cancer with the lowest overall 5-y relative survival rate. Gene expression profiling of PDAC revealed an overexpression of the macrophage migration inhibitory factor (MIF), a lymphokine involved in cell-mediated immunity and inflammation, as well as in the regulation of cellular signal transduction.

MATERIALS AND METHODS

Endogenous MIF expression was silenced by treatment of pancreatic cancer cell lines using two independent MIF siRNAs. The expression of MIF RNA and protein after siRNA treatment was investigated using quantitative RT-PCR and Western blot. Induction of apoptosis was analyzed using fluorescence activated cell sorting (FACS).

RESULTS

Transfection of MiaPaCa-2 cells with MIF siRNA resulted in a reduction of MIF RNA and protein levels by more than 85%. After treatment, we observed an inhibition of cellular proliferation accompanied by induction of apoptosis. Analysis of the phosphorylation state of Akt showed a markedly increase of the phosphorylation at the Thr308 residue.

CONCLUSIONS

Using post-transcriptional silencing with small interfering RNAs, we could show that MIF acts as an autocrine growth factor involved in cell cycle progression. Since MIF is a secreted protein, a therapy directed against MIF or its receptor might lead to a significant growth reduction of PDAC.

Macrophage migration inhibitory factor (MIF), enzymatic activity and the inflammatory response

Macrophage migration inhibitory factor represents a key cytokine in human diseases. It plays an important role in both innate and acquired immunity and has been shown to be a key mediator of inflammatory diseases. More recently MIF has been implicated in cancer pathogenesis. Over the decades its structure and functions have been elucidated and this has led to it being further classified as a hormone and an enzyme. It has isomerase enzymatic activity and increasing evidence implicates this activity in inflammatory disease. Consequently, there is increasing interest in developing small molecular weight inhibitors which could target this novel enzymatic activity in disease. (c) 2009 International Union of Biochemistry and Molecular Biology, Inc.

A gene expression ratio-based diagnostic test for bladder cancer

Purpose

Bladder cancer is relatively common but early detection techniques such as cystoscopy and cytology are somewhat limited. We developed a broadly applicable, platform-independent and clinically relevant method based on simple ratios of gene expression to diagnose human cancers. In this study, we sought to determine whether this technique could be applied to the diagnosis of bladder cancer.

Experimental design

We developed a model for the diagnosis of bladder cancer using expression profiling data from 80 normal and tumor bladder tissues to identify statistically significant discriminating genes with reciprocal average expression levels in each tissue type. The expression levels of select genes were used to calculate individual gene pair expression ratios in order to assign diagnosis. The optimal model was examined in two additional published microarray data sets and using quantitative RT-PCR in a cohort of 13 frozen benign bladder urothelium samples and 13 bladder cancer samples from our institution.

Results

A five-ratio test utilizing six genes proved to be 100% accurate (26 of 26 samples) for distinguishing benign from malignant bladder tissue samples (P < 10⁻⁶).

Conclusions

: We have provided a proof of principle study for the use of gene expression ratios in the diagnosis of bladder cancer. This technique may ultimately prove to be a useful adjunct to cytopathology in screening urine specimens for bladder cancer.

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.

Expression of macrophage migration inhibitory factor relates to survival in high-grade osteosarcoma

Macrophage migration inhibitory factor (MIF), a proinflammatory cytokine, is implicated in many aspects of tumor progression, including cell proliferation, invasion, and angiogenesis. We asked if MIF expression predicts survival and if it is associated with angiogenesis and cell invasion in osteosarcoma. We performed immunohistochemistry for MIF expression in prechemotherapy biopsy specimens of 58 patients with osteosarcoma. To investigate the role of MIF in angiogenesis, microvessel density was measured and compared with MIF expression. We also treated osteosarcoma cell lines (U2-OS and MG63) with MIF and measured vascular endothelial growth factor, a potent proangiogenic factor, by enzyme-linked immunosorbent assay. To study the role of MIF in cell invasion, Boyden chamber assay was performed after knockdown of MIF by short interfering RNA. MIF independently predicted overall survival and metastasis-free survival. MIF expression correlated with microvessel density and induced a dose-dependent increase in vascular endothelial growth factor. Knockdown of MIF by short interfering RNA resulted in decreased cell invasion. These results suggest MIF could serve as a prognostic marker and a potential therapeutic target for osteosarcoma.

LEVEL OF EVIDENCE

Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Overexpression of macrophage migration inhibitory factor induces angiogenesis in human breast cancer

Macrophage migration inhibitory factor (MIF) is known to be an important contributor to tumor progression. Overexpression of MIF has been reported in different types of tumors. However, the correlation between MIF expression and tumor pathologic features in patients with breast cancer has not been elucidated. In this study, we examined the expression of MIF, vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8) in human tissues with or without tumor. In addition, we investigated the expression of MIF in MDA-MB-231, MCF-7 (breast cancer cell lines) and MCF-10A (epithelial cell line) cells, and its effect on VEGF and IL-8. We found that MIF was overexpressed in breast cancer tissues compared with normal ones. The level of MIF showed the positive correlation between the expression of IL-8 and tumor microvessel density (MVD). The patients with positive MIF expression in tumor tissues showed a significantly worse disease-free survival compared with negative ones. Increased MIF serum levels were also found to correlate with higher levels of IL-8 in the sera of the patients with breast cancer. In vitro experiments successfully detected MIF in breast cell lines. However, the expression level of it by normal epithelial cells was much less than that of cancer cells. Exogenous MIF did not cause endothelial tube formation and migration but induced a dose dependent increase in VEGF and IL-8 secretion in breast cancer cell lines. In summary, our studies show that human breast cancer tissue expresses MIF. Its in vitro effect on VEGF and IL-8 indicates that MIF may contribute to tumor in angiogenesis and thus play an important role in the pathogenesis of breast cancer.

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.

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.

Expression of macrophage migration inhibitory factor and its effect on cell proliferation and angiogenesis in human liver cancer

AIM: To determine the expression of macro-phage migration inhibitory factor (MIF) in hepatocellular carcinoma (HCC) and its effect on cell proliferation and angiogenesis.

METHODS: The protein expression of MIF, interleukin-8 (IL-8), and vascular endothelial factor (VEGF) as well as microvessel density (MVD) were examined by immunochemistry in HCC tissues (n = 40), cancer-adjacent liver tissues (n = 40) and normal liver tissues (n = 10). At the same time, real time quantitative polymerase chain reaction (RQ-PCR) was used to detect the mRNA levels of MIF, VEGF and IL-8. After human hepatocarcinama cell line Bel-7402 was treated with recombinant MIF (rMIF), cell proliferation was detected by MTT assay and the secretion levels and mRNA expression of VEGF and IL-8 were examined by enzyme linked immunosorbent assay (ELISA) and RQ-PCR, respectively.

RESULTS: The positive rates of MIF, IL-8 and VEGF in HCC tissues were significantly higher than those in normal liver tissues (72.5% vs 30.0%, 67.5% vs 20.0%, 62.5% vs 30.0%, all P < 0.01). The expression of MIF and IL-8 were markedly correlated with VEGF expression (r = 0.271, P < 0.05) and MVD (r = 0.284, P < 0.05). VEGF concentration in the supernatant of Bel-7402 cells was higher (900.00 ± 264.58 ng/L) than that in the controls (180 ± 50 ng/L) at the 24^th hour after rMIF treatment (P < 0.01). However, there was no significant variation in IL-8 concentration (P > 0.05). The post-treatment level of VEGF mRNA was 6.86 times as high as that without treatment (P < 0.05), and there was no significant change in IL-8 mRNA expression (P > 0.05).

CONCLUSION: The over-expression of MIF plays a crucial role in the angiogenesis of liver cancer and the roles of MIF and IL-8 may be realized via VEGF.

Substance P induces localization of MIF/alpha1-inhibitor-3 complexes to umbrella cells via paracellular transit through the urothelium in the rat bladder

BACKGROUND

Macrophage migration inhibitory factor (MIF) is released into the intraluminal fluid during bladder inflammation in the rat complexed to alpha1-inhibitor-3 (A1-I3; a rodent proteinase inhibitor in the alpha-macroglobulin family). The location of A1-I3 in the bladder had not been investigated. Therefore, we examined the location of A1-I3 and MIF/A1-I3 complexes in the bladder and changes due to experimental inflammation.

METHODS

Anesthetized male rats had bladders removed with no treatment (intact) or were injected with Substance P (SP; s.c.; saline vehicle). After one hour intraluminal fluid was removed, bladder was excised and MIF and A1-I3 levels were determined using ELISA and/or western-blotting. MIF co-immunoprecipitation determined MIF/A1-I3 complexes in the bladder. Bladder sections were immunostained for A1-I3 and MIF/A1-I3.

RESULTS

A1-I3 immunostaining was observed in interstitial spaces throughout the bladder (including submucosa) but not urothelium in intact and saline-treated rats. RT-PCR showed that the bladder does not synthesize A1-I3, therefore, A1-I3 in the interstitial space of the bladder must be plasma derived. In SP-treated rats, A1-I3 in the bladder increased and A1-I3 was observed traversing through the urothelium. Umbrella cells that do not show MIF and/or A1-I3 immunostaining in intact or saline-treated rats, showed co-localization of MIF and A1-I3 after SP-treatment. Western blotting demonstrated that in the bladder MIF formed non-covalent interactions and also binds covalently to A1-I3 to form high molecular weight MIF/A1-I3 complexes (170, 130 and 75-kDa, respectively, verified by co-immunoprecipitation). SP-induced inflammation selectively reduced 170-kDa MIF/A1-I3 in the bladder while increasing 170 and 130-kDa MIF/A1-I3 in the intraluminal fluid.

CONCLUSION

A1-I3 and MIF/A1-I3 complexes are resident in bladder interstitium. During SP-induced inflammation, MIF/A1-I3 complexes are released from the bladder into the lumen. Binding of MIF/A1-I3 complexes to urothelial cells during inflammation suggests these complexes participate in the inflammatory reaction through activation of receptors for MIF and/or for A1-I3.

Helicobacter pylori CagA-dependent macrophage migration inhibitory factor produced by gastric epithelial cells binds to CD74 and stimulates procarcinogenic events

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine that has recently been implicated in carcinogenesis. Helicobacter pylori, which is closely linked to gastric cancer, induces the gastric epithelium to produce proinflammatory cytokines, including MIF. MIF can bind to CD74, which we have previously shown to be highly expressed on the surface of gastric epithelial cells (GEC) during H. pylori infection. In this study, we sought to investigate the role of the H. pylori-induced MIF on epithelial proliferation and procarcinogenic events. Upon establishing a role for the H. pylori CagA virulence factor in MIF production, MIF binding to CD74 on GEC was confirmed. rMIF and H. pylori were shown to increase GEC proliferation, which was decreased when cagA- strains were used and when CD74 was blocked by mAbs. Apoptosis was also decreased by MIF, but increased by cagA- strains that induced much lower amounts of MIF than the wild-type bacteria. Furthermore, MIF binding to CD74 was also shown to decrease p53 phosphorylation and up-regulate Bcl-2 expression. This data describes a novel system in which an H. pylori virulence factor contributes to the production of a host factor that in turn up-regulates procarcinogenic events by the gastric epithelium.

Development and Validation of a Multiplex Add-On Assay for Sepsis Biomarkers Using xMAP Technology

Background: Sepsis is a common and often fatal disease. Because sepsis can be caused by many different organisms, biomarkers that can aid in diagnosing sepsis and monitoring treatment efficacy are highly warranted. New sepsis markers may provide additional information to complement the currently used markers.

Methods: We used a combination of in-house and commercially available multiplex immunoassays based on Luminex® xMAP technology to assay biomarkers of potential interest in EDTA-plasma samples.

Results: A 3-plex assay for soluble urokinase plasminogen activator receptor (suPAR), soluble triggering receptor expressed on myeloid cells-1 (sTREM-1), and macrophage migration inhibiting factor (MIF) was developed and validated in-house. This 3-plex assay was added to a commercially available interleukin-1β (IL-1β), IL-6, IL-8, granulocyte/macrophage colony-stimulating factor, and tumor necrosis factor-α human cytokine panel. No cross-reactivity was observed when the assays were combined. Correlation between values obtained with the 8-plex, the 5-cytokine panel, the 3 in-house 1-plex assays, and a suPAR ELISA ranged from 0.86 to 0.99. Mean within- and between-run CVs were 8.0% and 11%, respectively. Recoveries of suPAR, sTREM-1, and MIF calibrators were 108%, 88%, and 51%, respectively. In plasma collected from 10 patients with bacterial sepsis confirmed by blood culture, the assay detected significantly increased concentrations of all 8 analytes compared with healthy controls.

Conclusions: A commercially available xMAP panel can be expanded with markers of interest. The combined multiplex assay can measure the 8 analytes with high reproducibility. The xMAP technology is an appealing tool for assaying conventional cytokines in combination with new markers.