A proinflammatory cytokine inhibits p53 tumor suppressor activity

A 16-residue peptide fragment of macrophage migration inhibitory factor, MIF-(50-65), exhibits redox activity and has MIF-like biological functions

Macrophage migration inhibitory factor (MIF) is a cytokine that participates in the host inflammatory response. A Cys-Xaa-Xaa-Cys (CXXC)-based thiol-protein oxidoreductase activity of MIF is associated with certain biological functions. Peptides spanning the CXXC region of thiol-protein oxidoreductases retain some biochemical properties of the full-length protein. We report on the characterization of CXXC-spanning MIF-(50-65) and its serine variant, C57S/C60S-MIF-(50-65). Following disulfide-mediated cyclization, MIF-(50-65) adapted a beta-turn conformation comparable with that of beta-turn-containing cyclo-57,60-[Asp57,Dap60]MIF-(50-65). MIF-(50-65) had a redox potential E'0 of -0.258 V and formed mixed disulfides with glutathione and cysteine. MIF-(50-65) but not C57S/C60S-MIF-(50-65) had oxidoreductase activity in vitro. Intriguingly, MIF-(50-65) exhibited MIF-like cellular activities. The peptide but not its variant had glucocorticoid overriding and proliferation-enhancing activity and stimulated ERK1/2 phosphorylation. MIF-(50-65) and its variant bound to the MIF-binding protein JAB1 and enhanced cellular levels of p27Kip1. As the peptide and its variant were endocytosed at similar efficiency, sequence 50-65 appears sufficient for the JAB1-related effects of MIF, whereas other activities require CXXC. Cyclo-57,60-[Asp57,Dap60]MIF-(50-65) activated ERK1/2, indicating that CXXC-dependent disulfide and beta-turn formation is associated with an activity-inducing conformation. We conclude that CXXC and sequence 50-65 are critical for the activities of MIF. MIF-(50-65) is a surprisingly short sequence with MIF-like functions that could be an excellent molecular template for MIF therapeutics.

Review article: colitis-associated cancer -- time for new strategies

Colorectal cancer (CRC) remains a feared and potentially life-threatening complication of both ulcerative colitis and Crohn's colitis. Currently, the main preventive strategy is a secondary one, i.e. surveillance colonoscopy usually after 8 years of disease duration, when the risk for neoplasia begins to increase. Despite its widespread acceptance, dysplasia and cancer surveillance is unproven in terms of reducing mortality or morbidity and there is a remarkable lack of uniformity in the manner in which it is practised. In this review article, the pitfalls of dysplasia surveillance are summarized and the need for novel chemopreventive and perhaps pharmabiotic approaches for prevention are highlighted.

The p53-dependent effects of macrophage migration inhibitory factor revealed by gene targeting

Macrophage migration inhibitory factor (MIF) is a mediator of host immunity and functions as a high, upstream activator of cells within the innate and the adaptive immunological systems. Recent studies have suggested a potentially broader role for MIF in growth regulation because of its ability to antagonize p53-mediated gene activation and apoptosis. To better understand MIF's activity in growth control, we generated and characterized a strain of MIF-knockout (MIF-KO) mice in the inbred, C57BL/6 background. Embryonic fibroblasts from MIF-KO mice exhibit p53-dependent growth alterations, increased p53 transcriptional activity, and resistance to ras-mediated transformation. Concurrent deletion of the p53 gene in vivo reversed the observed phenotype of cells deficient in MIF. In vivo studies showed that fibrosarcomas induced by the carcinogen benzo[alpha]pyrene are smaller in size and have a lower mitotic index in MIF-KO mice relative to their WT counterparts. The data provide direct genetic evidence for a functional link between MIF and the p53 tumor suppressor and indicate an important and previously unappreciated role for MIF in carcinogenesis.

Regulation of p53 by macrophage migration inhibitory factor in inflammatory arthritis

OBJECTIVE

To study the capacity of macrophage migration inhibitory factor (MIF) to regulate proliferation, apoptosis, and p53 in an animal model of rheumatoid arthritis (RA) and in fibroblast-like synoviocytes (FLS) from humans with RA.

METHODS

Antigen-induced arthritis (AIA) was induced in MIF(-/-) mice and littermate controls. FLS were obtained from patients with RA. Western blotting and immunohistochemistry were used to measure p53 in cells and tissues. Apoptosis was detected in cells by flow cytometry using TUNEL and annexin V/propidium iodide labeling. Apoptosis in tissue was detected using TUNEL. Proliferation was assessed in cultured cells and tissue by (3)H-thymidine incorporation and Ki-67 immunostaining, respectively.

RESULTS

MIF inhibited p53 expression in human RA FLS. Levels of p53 were correspondingly increased in MIF(-/-) mouse tissues and cells. Spontaneous and sodium nitroprusside-induced apoptosis were significantly increased in MIF(-/-) cells. In vitro exposure of FLS to MIF reduced apoptosis and significantly induced FLS proliferation. Synoviocyte proliferation in MIF(-/-) mice was correspondingly reduced. A decrease in the severity of AIA in MIF(-/-) mice was associated with an increase in p53 and apoptosis in synovium. Evidence of in situ proliferation was scant in this model, and no difference in in situ proliferation was detectable in MIF(-/-) mice compared with wild-type mice.

CONCLUSION

These results indicate a role for MIF in the regulation of p53 expression and p53-mediated events in the inflamed synovium and support the hypothesis that MIF is of critical importance in the pathogenesis of RA.

Review article: inflammation-related promotion of gastrointestinal carcinogenesis--a perigenetic pathway

Chronic inflammation has been reported to accelerate neoplasmas in gastrointestinal tract. Certain bacteria including Helicobacter pylori directly interact with host cells, induce proinflammatory cytokines and stimulate production of free radicals. Free radicals cause mutations in target cells so that neoplastic clones are established. Accumulation of such genetic alterations may cause malignant transformation of some established clones. In addition, inflammatory alterations may promote growth, expansion and invasion of gastrointestinal epithelial cells. The latter changes caused by inflammation may occur even without further genetic mutations or epigenetic alterations, and therefore may be categorized as 'perigenetic alterations' of neoplastic cells. For an example, tumour necrosis factor alpha (TNF-alpha) plays pivotal roles not only in the reduction but also in the growth, invasion and metastases of certain neoplasmas. Our studies show that TNF-alpha increases intracellular radical production, degradates E-cadherin / beta-catenin complex and promotes dispersion and migration in epithelial cells transformed with an activated src oncogene (v-src). These data indicate that an inflammatory cytokine induces the malignant potential of src-activated neoplastic cells. Interestingly, TNF-alpha also induced these phenotypic changes in nonmutated cells whose c-Src was activated by TGF-alpha, suggesting that the invasive properties of the cell were not necessarily related to gene mutation. Furthermore, certain radical scavengers suppressed the invasive phenotype of the cells. These results indicate that perigenetic alterations are an important target of pharmacological intervention of carcinogenesis.

Macrophage migration inhibitory factor and host innate immune defenses against bacterial sepsis

Macrophages are essential effector cells of innate immunity that play a pivotal role in the recognition and elimination of invasive microorganisms. Mediators released by activated macrophages orchestrate innate and adaptive immune host responses. The cytokine macrophage migration inhibitory factor (MIF) is an integral mediator of the innate immune system. Monocytes and macrophages constitutively express large amounts of MIF, which is rapidly released after exposure to bacterial toxins and cytokines. MIF exerts potent proinflammatory activities and is an important cytokine of septic shock. Recent investigations of the mechanisms by which MIF regulates innate immune responses to endotoxin and gram-negative bacteria indicate that MIF acts by modulating the expression of Toll-like receptor 4, the signal-transducing molecule of the lipopolysaccharide receptor complex. Given its role in innate immune responses to bacterial infections, MIF is a novel target for therapeutic intervention in patients with septic shock.

MIF signal transduction initiated by binding to CD74

Macrophage migration inhibitory factor (MIF) accounts for one of the first cytokine activities to have been described, and it has emerged recently to be an important regulator of innate and adaptive immunity. MIF is an upstream activator of monocytes/macrophages, and it is centrally involved in the pathogenesis of septic shock, arthritis, and other inflammatory conditions. The protein is encoded by a unique but highly conserved gene, and X-ray crystallography studies have shown MIF to define a new protein fold and structural superfamily. Although recent work has begun to illuminate the signal transduction pathways activated by MIF, the nature of its membrane receptor has not been known. Using expression cloning and functional analysis, we report herein that CD74, a Type II transmembrane protein, is a high-affinity binding protein for MIF. MIF binds to the extracellular domain of CD74, and CD74 is required for MIF-induced activation of the extracellular signal-regulated kinase-1/2 MAP kinase cascade, cell proliferation, and PGE2 production. A recombinant, soluble form of CD74 binds MIF with a dissociation constant of approximately 9 x 10-9 Kd, as defined by surface plasmon resonance (BIAcore analysis), and soluble CD74 inhibits MIF-mediated extracellular signal-regulated kinase activation in defined cell systems. These data provide a molecular basis for MIF's interaction with target cells and identify it as a natural ligand for CD74, which has been implicated previously in signaling and accessory functions for immune cell activation.

Synergistic effects of nimesulide and 5-fluorouracil on tumor growth and apoptosis in the implanted hepatoma in mice

AIM: To compare the effect of nimesulide or/and 5-fluorouracil (5-FU) on tumor growth inhibition and apoptosis in mice with the implanted hepatoma and to observe their possible interactions.

METHODS: The inhibitory effects on tumor growth was evaluated by inhibition rate. Apoptosis was assessed by the ultrastructural, flow cytometry features and the DNA ladder demonstrated by agarose gel electrophoresis. PGE₂ level was determined by radioimmunoassay. Expression levels of c-jun, c-fos and p53 were evaluated by western blotting.

RESULTS: Nimesulide or 5-FU alone inhibited the growth of hepatoma, while a synergistic effect was observed for a combined use of both. More pronounced morphologic changes for tumor cell apoptosis and the DNA ladder were found for the latter treatment. Expression levels of c-jun and p53 were found to be elevated for the tumors from mice treated with nimesulide and 5-FU comparing to those with either of them, but a reduced PGE₂ level was observed only for the treatment with nimesulide. No change was detected on c-fos expression.

CONCLUSION: Nimesulide and 5-FU appear to have synergistic effects for the growth inhibition and apoptosis induction. Both were found to be overexpressed in p53 and c-jun proteins, rather than that of c-fos, associations with the resulted apoptosis.

Macrophage migration inhibitory factor (MIF): Its potential role in tumor growth and tumor-associated angiogenesis

Macrophage migration inhibitory factor (MIF) functions as a pluripotent cytokine involved in broad-spectrum pathophysiological events in association with inflammation and immune responses. Several reports, including ours, have suggested that MIF is also involved in tumorigenesis; however, its precise role has not been fully investigated. We examined the effectiveness of anti-MIF antibodies on tumor growth and tumor-associated angiogenesis using murine colon cancer cell line, colon 26. We observed a significant inhibition of growth of tumors embedded on the back of BALB/c mice by treatment with anti-MIF antibodies. Next, we implanted a Millipore chamber filled with colon cancer cells in the subcutaneous fascia of the flanks of mice and then treated them with anti-MIF antibodies. We found that angiogenesis was markedly suppressed within the region of the subcutaneous fascia that was in contact with the chamber. To further assess the role of MIF in tumorigenesis, we established MIF transgenic mice, which demonstrated that tumor growth and the associated angiogenesis were significantly enhanced in comparison with control mice.

Macrophage migration inhibitory factor

Macrophage migration inhibitory factor (MIF) is a ubiquitous protein that is found in virtually all cells. Its precise function in the majority of cells is not known, but studies performed over the last decade indicate that it is a critical upstream regulator of the innate and acquired immune response. MIF is released under a variety of circumstances, regulates cytokine secretion and the expression of receptors that are involved in innate immunity, inhibits p53 function, and activates components of the mitogen-activated protein kinase and Jun-activation domain-binding protein-1 (Jab-1) pathways. Compelling in vitro and in vivo evidence has focused attention on this protein as a new therapeutic target for inflammatory and autoimmune diseases. Unique structural features, including an intrinsic catalytic activity, offer attractive opportunities for the discovery and design of therapeutic MIF inhibitors.

Macrophage migration inhibitory factor deficiency is associated with altered cell growth and reduced susceptibility to Ras-mediated transformation

Macrophage migration inhibitory factor (MIF) has been shown to functionally inactivate the p53 tumor suppressor and to inhibit p53-responsive gene expression and apoptosis. To better understand the role of MIF in cell growth and tumor biology, we evaluated MIF-null embryonic fibroblasts with respect to their immortalization and transformation properties. Although minor deviations in the growth characteristics of MIF(-/-) fibroblasts were observed under normal culture conditions, MIF-deficient cells were growth-impaired following the introduction of immortalizing oncogenes. The growth retardation by the immortalized MIF(-/-) cultures correlated with their reduced susceptibility to Ras-mediated transformation. Our results identify E2F as part of the restraining mechanism that is activated in response to oncogenic signaling and show that the biological consequences of E2F induction in MIF(-/-) fibroblasts vary depending on the p53 status, inducing predominantly G(1) arrest or apoptosis in p53-positive cells. This E2F activity is independent of Rb binding, but contingent on binding DNA. Resistance to oncogenic transformation by MIF(-/-) cells could be overcome by concomitant interference with p53- and E2F-responsive transcriptional control. Our results demonstrate that MIF plays a role in an E2F/p53 pathway that operates downstream of Rb regulation and implicate MIF as a mediator of normal and malignant cell growth.

The cytokine macrophage migration inhibitory factor reduces pro-oxidative stress-induced apoptosis

The cytokine macrophage migration inhibitory factor (MIF) exhibits pro- and anti-inflammatory activities and regulates cell proliferation and survival. We investigated the effects of MIF on apoptosis. As MIF exhibits oxidoreductase activity and participates in regulating oxidative cell stress, we studied whether MIF could affect oxidative stress-induced apoptosis. We demonstrated that MIF exhibits antiapoptotic activity in various settings. MIF suppressed camptothecin-induced apoptosis in HeLa and Kym cells and HL-60 promyeloblasts. Both exogenous MIF and endogenous MIF, induced following overexpression through tetracycline (tet) gene induction, led to significant suppression of apoptosis. Apoptosis reduction by MIF was also observed in T cells. A role for MIF in redox stress-induced apoptosis was addressed by comparing the effects of rMIF with those of the oxidoreductase mutant C60SMIF. Endogenous overexpression of C60SMIF was similar to that of MIF, but C60SMIF did not suppress apoptosis. Exogenous rC60SMIF inhibited apoptosis. A role for MIF in oxidative stress-induced apoptosis was directly studied in HL-60 leukocytes and tet-regulated HeLa cells following thiol starvation or diamide treatment. MIF protected these cells from redox stress-induced apoptosis and enhanced cellular glutathione levels. As overexpressed C60SMIF did not protect tet-regulated HeLa cells from thiol starvation-induced apoptosis, it seems that the redox motif of MIF is important for this function. Finally, overexpression of MIF inhibited phosphorylation of endogenous c-Jun induced by thiol starvation, indicating that MIF-based suppression of apoptosis is mediated through modulation of c-Jun N-terminal kinase activity. Our findings show that MIF has potent antiapoptotic activities and suggest that MIF is a modulator of pro-oxidative stress-induced apoptosis.

Inflammation and cancer

Recent data have expanded the concept that inflammation is a critical component of tumour progression. Many cancers arise from sites of infection, chronic irritation and inflammation. It is now becoming clear that the tumour microenvironment, which is largely orchestrated by inflammatory cells, is an indispensable participant in the neoplastic process, fostering proliferation, survival and migration. In addition, tumour cells have co-opted some of the signalling molecules of the innate immune system, such as selectins, chemokines and their receptors for invasion, migration and metastasis. These insights are fostering new anti-inflammatory therapeutic approaches to cancer development.

Inflammation and cancer

Recent data have expanded the concept that inflammation is a critical component of tumour progression. Many cancers arise from sites of infection, chronic irritation and inflammation. It is now becoming clear that the tumour microenvironment, which is largely orchestrated by inflammatory cells, is an indispensable participant in the neoplastic process, fostering proliferation, survival and migration. In addition, tumour cells have co-opted some of the signalling molecules of the innate immune system, such as selectins, chemokines and their receptors for invasion, migration and metastasis. These insights are fostering new anti-inflammatory therapeutic approaches to cancer development.

Nitric oxide-induced cellular stress and p53 activation in chronic inflammation

Free radical-induced cellular stress contributes to cancer during chronic inflammation. Here, we investigated mechanisms of p53 activation by the free radical, NO. NO from donor drugs induced both ataxia-telangiectasia mutated (ATM)- and ataxia-telangiectasia mutated and Rad3-related-dependent p53 posttranslational modifications, leading to an increase in p53 transcriptional targets and a G(2)M cell cycle checkpoint. Such modifications were also identified in cells cocultured with NO-releasing macrophages. In noncancerous colon tissues from patients with ulcerative colitis (a cancer-prone chronic inflammatory disease), inducible NO synthase protein levels were positively correlated with p53 serine 15 phosphorylation levels. Immunostaining of HDM-2 and p21(WAF1) was consistent with transcriptionally active p53. Our study highlights a pivotal role of NO in the induction of cellular stress and the activation of a p53 response pathway during chronic inflammation.

Up-regulation of macrophage migration inhibitory factor gene and protein expression in glial tumor cells during hypoxic and hypoglycemic stress indicates a critical role for angiogenesis in glioblastoma multiforme

Glioblastoma multiforme (GBM) is the most malignant variant of human glial tumors. A prominent feature of this tumor is the occurrence of necrosis and vascular proliferation. The regulation of glial neovascularization is still poorly understood and the characterization of factors involved in this process is of major clinical interest. Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine released by leukocytes and by a variety of cells outside of the immune system. Recent work has shown that MIF may function to regulate cellular differentiation and proliferation in normal and tumor-derived cell lines, and may also contribute to the neovascularization of tumors. Our immunohistological analysis of MIF distribution in GBM tissues revealed the strong MIF protein accumulation in close association with necrotic areas and in tumor cells surrounding blood vessels. In addition, MIF expression was frequently associated with the presence of the tumor-suppressor gene p53. To substantiate the concept that MIF might be involved in the regulation of angiogenesis in GBM, we analyzed the MIF gene and protein expression under hypoxic and hypoglycemic stress conditions in vitro. Northern blot analysis showed a clear increase of MIF mRNA after hypoxia and hypoglycemia. We could also demonstrate that the increase of MIF transcripts on hypoxic stress can be explained by a profound transcriptional activation of the MIF gene. In parallel to the increase of MIF transcripts, we observed a significant rise in extracellular MIF protein on angiogenic stimulation. The data of our preliminary study suggest that the up-regulation of MIF expression during hypoxic and hypoglycemic stress might play a critical role for the neovascularization of glial tumors.

Characterization of the levels of expression of retinoic acid receptors, galectin-3, macrophage migration inhibiting factor, and p53 in 51 adamantinomatous craniopharyngiomas

OBJECT

Craniopharyngiomas are histopathologically defined as benign tumors that can behave very aggressively at the clinical level. They can originate from different types of embryonal epithelial tissue in which correct spatiotemporal regulation has been disrupted at the effector production level. The goal of this study was to determine the efficacy of using selected biological markers to distinguish between recurring and nonrecurring craniopharyngiomas.

METHODS

The authors used computer-assisted microscopy to determine quantitatively the immunohistochemical levels of expression of selected markers, including retinoic acid receptors (RARs), as response elements to retinoic acid in a series of 51 adamantinomatous craniopharyngiomas. These tumors may also originate as the result of physiological defects in the apoptosis-mediated elimination of embryological remnants of epithelial tissue. Galectin-3, p53, and the macrophage migration inhibiting factor (MIF) are known to play crucial roles in these processes. The authors quantitatively determined the levels of expression of these substances in this series of 51 craniopharyngiomas. The data show that all craniopharyngiomas were immunoreactive for RARalpha, whereas their immunoreactivity for RARbeta and RARgamma varied dramatically from one case to another. Craniopharyngiomas with low levels of RARbeta and high levels of RARgamma are more likely to recur than those with higher levels of RARbeta and lower levels of RARgamma. Rapidly recurring craniopharyngiomas also show significantly lower levels of expression of galectin-3 and MIF than nonrecurring or slowly recurring cases. Few tumors exhibited p53 immunopositivity.

CONCLUSIONS

The data indicate that even in the so-called adamantinomatous group of craniopharyngiomas, several subgroups with different clinical behavior patterns can be identified on the basis of differentiation markers relating mainly to the presence or absence of RARbeta and RARgamma.

Regulation of macrophage migration inhibitory factor expression by glucocorticoids in vivo

Glucocorticoid hormones are important anti-inflammatory agents because of their anti-inflammatory and proapoptotic action within the immune system. Their clinical usefulness remains limited however by side effects that result in part from their growth inhibitory action on sensitive target tissues. The protein mediator, macrophage migration inhibitory factor (MIF), is an important regulator of the host immune response and exhibits both glucocorticoid-antagonistic and growth-regulatory properties. MIF has been shown to contribute significantly to the development of immunopathology in several models of inflammatory disease. Although there is emerging evidence for a functional interaction between MIF and glucocorticoids in vitro, little is known about their reciprocal influence in vivo. We investigated the expression of MIF in rat tissues after ablation of the hypothalamic-pituitary-adrenal axis and after high-dose glucocorticoid administration. MIF expression is constitutive and independent of the influence of adrenal hormones. Hypophysectomy and the attendent loss of pituitary hormones, by contrast, decreased MIF protein content in the adrenal gland. Administration of dexamethasone was found to increase MIF protein expression in those organs that are considered to be sensitive to the growth inhibitory effects of glucocorticoids (immune and endocrine tissues, skin, and muscle). This increase was most likely because of a posttranscriptional regulatory effect because tissue MIF mRNA levels were not influenced by dexamethasone treatment. Finally, MIF immunoneutralization enhanced lymphocyte egress from blood during stress-induced lymphocyte redistribution, consistent with a functional interaction between MIF and glucocorticoids on immune cell trafficking in vivo. These findings suggest a role for MIF in both the homeostatic and physiological action of glucocorticoids in vivo.

Inflammation and cancer

Recent data have expanded the concept that inflammation is a critical component of tumour progression. Many cancers arise from sites of infection, chronic irritation and inflammation. It is now becoming clear that the tumour microenvironment, which is largely orchestrated by inflammatory cells, is an indispensable participant in the neoplastic process, fostering proliferation, survival and migration. In addition, tumour cells have co-opted some of the signalling molecules of the innate immune system, such as selectins, chemokines and their receptors for invasion, migration and metastasis. These insights are fostering new anti-inflammatory therapeutic approaches to cancer development.

Oral lichen planus: causes, diagnosis and management

Oral lichen planus (OLP) is a chronic inflammatory disease of unknown etiology. In this paper we review the clinical and histological features of OLP, process of OLP diagnosis, causes of OLP, management of OLP patients and medical treatment of OLP lesions. Approximately 0.2 per cent OLP patients develop intra-oral carcinoma each year compared with approximately 0.005 per cent Australian adults. Possible mechanisms of increased oral cancer risk in OLP patients are presented. The aims of current OLP therapy are to eliminate mucosal erythema and ulceration, alleviate symptoms and reduce the risk of oral cancer. Patient education may improve the outcomes of OLP therapy and further reduce the risk of oral cancer in OLP patients. Although OLP may be diagnosed clinically, appropriate specialist referral is required for: (i) histological diagnosis; (ii) assessment of causative/exacerbating factors, associated diseases and oral cancer risk; (iii) patient education and management; (iv) medical treatment; and (v) long-term review and re-biopsy as required.

Macrophage migration inhibitory factor (MIF) expression in human glioblastomas correlates with vascular endothelial growth factor (VEGF) expression

Macrophage migration inhibitory factor (MIF) is a peptide released upon hypothalamo-pituitary stimulation that acts as a potent endogenous antagonist of the glucocorticoid inhibition of acute inflammatory response and subsequent antigen-specific response. MIF also sustains tumour growth as it promotes angiogenesis, overcomes p53-mediated cell growth arrest and inhibits tumour-specific immune responses. Using quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry, we studied MIF expression in 35 human glioblastomas and two normal brains. We compared these results with the expression of vascular endothelial growth factor (VEGF), the most potent angiogenic factor in glioblastomas. We detected MIF in normal cortical neurons and glial cells. All glioblastomas were positive for MIF mRNA with expression levels similar to or higher than those of normal brain. MIF immunoreactivity was seen mainly in tumour cells and less frequently in hyperplastic endothelial cells. The expressions of MIF and VEGF mRNA were strongly correlated (P < 0.0001). Our results demonstrate the expression of MIF in human glioblastomas, and indicate a close relationship with VEGF expression. This is of particular interest given the potential modulation of MIF by glucocorticosteroids.

The pathogenesis of oral lichen planus

Both antigen-specific and non-specific mechanisms may be involved in the pathogenesis of oral lichen planus (OLP). Antigen-specific mechanisms in OLP include antigen presentation by basal keratinocytes and antigen-specific keratinocyte killing by CD8(+) cytotoxic T-cells. Non-specific mechanisms include mast cell degranulation and matrix metalloproteinase (MMP) activation in OLP lesions. These mechanisms may combine to cause T-cell accumulation in the superficial lamina propria, basement membrane disruption, intra-epithelial T-cell migration, and keratinocyte apoptosis in OLP. OLP chronicity may be due, in part, to deficient antigen-specific TGF-beta1-mediated immunosuppression. The normal oral mucosa may be an immune privileged site (similar to the eye, testis, and placenta), and breakdown of immune privilege could result in OLP and possibly other autoimmune oral mucosal diseases. Recent findings in mucocutaneous graft-versus-host disease, a clinical and histological correlate of lichen planus, suggest the involvement of TNF-alpha, CD40, Fas, MMPs, and mast cell degranulation in disease pathogenesis. Potential roles for oral Langerhans cells and the regional lymphatics in OLP lesion formation and chronicity are discussed. Carcinogenesis in OLP may be regulated by the integrated signal from various tumor inhibitors (TGF-beta 1, TNF-alpha, IFN-gamma, IL-12) and promoters (MIF, MMP-9). We present our recent data implicating antigen-specific and non-specific mechanisms in the pathogenesis of OLP and propose a unifying hypothesis suggesting that both may be involved in lesion development. The initial event in OLP lesion formation and the factors that determine OLP susceptibility are unknown.

[Cancer genetic immunotherapy]

The concept of cancer immunotherapy and the resulting technical advances have evolved considerably during the last decade. However, cancer treatment by recombinant IL-2 or IFN-alpha still represents today the best therapeutic way for the treatment of renal carcinoma, melanoma and in some cases lymphoma. The immunotherapy approaches such as vaccination, gene and cellular therapy, have not yet demonstrated a sufficient clinical efficacy for the treatment of solid tumors. The goal of this review is to summarize the different approaches to cancer immunotherapy developed today. Specific approaches such as antigenic vaccination will be first described, then non-specific approaches such as gene transfer on the tumor site of immuno-stimulating genes will be discussed.

Regulation of HEF1 expression and phosphorylation by TGF-beta 1 and cell adhesion

Transforming growth factor-beta1 (TGF-beta1) is a multipotential cytokine, which regulates remodeling of tissue extracellular matrix during early tumorigenesis and wound healing. Human enhancer of filamentation-1 (HEF1), a multifunctional docking protein, is involved in integrin-based signaling, which affects cell motility, growth, and apoptosis. Our studies reveal that TGF-beta1 is a potent inducer of HEF1 gene transcription in human dermal fibroblasts. TGF-beta1 promoted HEF1 expression in a dose-dependent manner and resulted in a 16-fold increase in HEF1 protein level. TGF-beta1 had no effect on the stability of either HEF1 protein or mRNA. The TGF-beta1-induced HEF1 expression was independent of cell adhesion and resistant to cytoskeleton disruption. TGF-beta1 increased levels of both p105 and p115 HEF1 in adherent fibroblasts. Digestion with specific phosphatases indicated that the p115HEF1 resulted from serine/threonine phosphorylation of p105HEF1. The appearance of the p115HEF1 as well as tyrosine phosphorylation of p105HEF1 required cell adhesion and/or an organized cytoskeleton. An in vitro kinase assay indicated that p105HEF1 was a substrate for Src. PP1, a specific Src kinase inhibitor, was able to block adhesion-dependent tyrosine phosphorylation of p105HEF1. These findings suggest that TGF-beta1 regulates HEF1 gene expression and that HEF1 phosphorylation is dependent on cell adhesion and Src kinase activity.

Paracrine cyclooxygenase-2-mediated signalling by macrophages promotes tumorigenic progression of intestinal epithelial cells

In human colorectal adenomas or polyps, cyclooxygenase-2 is expressed predominantly by stromal (or interstitial) macrophages. Therefore, we tested the hypothesis that macrophage cyclooxygenase-2 has paracrine pro-tumorigenic activity using in vitro models of macrophage-epithelial cell interactions. We report that macrophages can promote tumorigenic progression of intestinal epithelial cells (evidenced by decreased cell-cell contact inhibition, increased proliferation and apoptosis, gain of anchorage-independent growth capability, decreased membranous E-cadherin expression, up-regulation of cyclooxygenase-2 expression, down-regulation of transforming growth factor-beta type II receptor expression and resistance to the anti-proliferative activity of transforming growth factor-beta(1)) in a paracrine, cyclooxygenase-2-dependent manner. Pharmacologically relevant concentrations (1-2 microM) of a selective cyclooxygenase-2 inhibitor had no detectable, direct effect on intestinal epithelial cells but inhibited the macrophage-epithelial cell signal mediating tumorigenic progression. Cyclooxygenase-2-mediated stromal-epithelial cell signalling during the early stages of intestinal tumorigenesis provides a novel target for chemoprevention of colorectal cancer (and other gastro-intestinal epithelial malignancies, which arise on a background of chronic inflammation, such as gastric cancer) and may explain the discrepancy between the concentrations of cyclooxygenase inhibitors required to produce anti-neoplastic effects in vitro and in vivo.

Adhesion-dependent signaling by macrophage migration inhibitory factor (MIF)

Proper stimulation of cell cycle progression and DNA synthesis requires cooperating signals from integrin and growth factor receptors. We previously found that the proinflammatory peptide, macrophage migration inhibitory factor (MIF), functions as an autocrine mediator of growth factor-dependent ERK MAP kinase activation and cell cycle progression. We now report that MIF secretion is induced by cell adhesion to fibronectin in quiescent mouse fibroblasts. Adhesion-mediated release of MIF subsequently promotes integrin-dependent activation of MAP kinase, cyclin D1 expression, and DNA synthesis. Secretion of MIF requires protein kinase C activity, and recombinant MIF reconstitutes the activation of MAP kinases in the presence of protein kinase C inhibition. Finally, we show that cells deficient in MIF have significantly higher retinoblastoma tumor suppressor and lower E2F transcriptional activities. These results suggest that MIF is an important autocrine mediator of adhesion-dependent signaling events and may provide mechanistic insight into how MIF regulates proliferative and oncogenic processes.

Release of macrophage migration inhibitory factor and CXCL8/interleukin-8 from lung epithelial cells rendered necrotic by influenza A virus infection

Bronchiolar epithelial cells are the prime targets for influenza A virus infection. It still remains to be clarified which signals are generated from these cells to initiate an immune response. Among chemokines, viral infection of primary lung epithelial cells triggered exclusively the release of CXCL8/interleukin-8 (IL-8), which contrasts with our previous observation that influenza A virus induced in monocytes the expression of mononuclear-leukocyte-attracting chemokines and even suppressed the production of neutrophil-attracting chemokines. Therefore, we speculated that it may be advantageous for respiratory epithelial cells to release primarily neutrophil-attracting CXCL8/IL-8 since neutrophils rapidly remove necrotic debris and are the first line of defense against bacterial superinfections. This concept has also been supported by our finding that influenza A virus infection led to necrosis of lung epithelial cells. This is in striking contrast to previous studies where influenza A virus infection induced apoptosis in monocytes and epithelial cells from origins other than the lung. Thus, the cell type instead of the virus determines which death pathway will be followed. In addition to the release of CXCL8/IL-8, we obtained a massive release of macrophage migration inhibitory factor (MIF) from virus-infected lung cells. However, whereas the CXCL8/IL-8 secretion was accompanied by induced gene activation, the transcription rate of MIF remained unchanged during the infection course and the virus-induced MIF release was predominantly a discharge from intracellular stores, suggesting that MIF is passively released upon cell death. Despite virus induced necrosis, the passively liberated MIF remained bioactive. Considering the well-established immunostimulatory effects of MIF on different leukocyte subsets, is its very likely that enhanced levels of MIF may contribute to the host immune response during the acute phase of influenza A virus infection in humans.

Human cytomegalovirus-mediated induction of MIF in fibroblasts

Human cytomegalovirus (HCMV) infection of fibroblasts induces the proinflammatory mediator macrophage migration inhibitory factor (MIF). Our in vitro experiments show that active HCMV infection alone is required to induce an early and sustained induction of MIF mRNA and protein production. Unlike in other infection models, in which MIF has been described to be released from preformed stores, our data conclusively show that HCMV infection triggers de novo synthesis and subsequent secretion of MIF. The kinetics of MIF protein production during HCMV infection points to an efficacious immune modulation, in which lymphocytes and monocytes are initially recruited by the early release of chemokines to sites of infection and locally activated by increasing concentrations of MIF.

The tautomerase active site of macrophage migration inhibitory factor is a potential target for discovery of novel anti-inflammatory agents

Macrophage migration inhibitory factor (MIF) is an immunoregulatory protein that is a potential therapeutic target for a number of inflammatory diseases. Evidence exists that an unexpected catalytic active site of MIF may have a biological function. To gain further insight into the role of the catalytic active site, a series of mutational, structural, and biological activity studies were performed. The insertion of an alanine between Pro-1 and Met-2 (PAM) abolishes a non-physiological catalytic activity, and this mutant is defective in the in vitro glucocorticoid counter-regulatory activity of MIF. The crystal structure of MIF complexed to (S,R)-3-(4-hydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid methyl ester (ISO-1), an inhibitor of MIF d-dopachrome tautomerase activity, reveals that ISO-1 binds to the same position of the active site as p-hydroxyphenylpyruvic acid, a substrate of MIF. ISO-1 inhibits several MIF biological activities, further establishing a role for the catalytic active site of MIF.

Interleukin-1beta expression in human gastric carcinoma with Epstein-Barr virus infection

The KT tumor is a transplantable strain of a human Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC), established in severe combined immunodeficiency (SCID) mice, with which the cytokine expression of EBVaGC can be investigated without interference from the infiltrating lymphocytes. As a part of a high-density oligonucleotide array (GeneChip) analysis of EBVaGC, the interleukin-1beta (IL-1beta) gene was the only cytokine gene that showed markedly higher expression in the KT tumor cells than in two tumor strains of EBV-negative GC. The results were confirmed by Northern blotting, Western blotting, and enzyme-linked immunosorbent assay. Furthermore, we demonstrated a positive signal for IL-1beta mRNA in the carcinoma cells of a surgically resected EBVaGC, but not in EBV-negative GC, by in situ hybridization. In vitro, IL-1beta increased the cell growth of a GC cell line, TMK1. Thus, IL-1beta may act as an autocrine growth factor in EBVaGC.

Inhibition of MIF bioactivity by rational design of pharmacological inhibitors of MIF tautomerase activity

The pro-inflammatory mediator macrophage migration inhibitory factor (MIF) is produced by immune and endocrine cells and inhibits the antiinflammatory activities of glucocorticoids. MIF also catalyzes the tautomerization of the non-naturally occurring D-isomer of dopachrome, phenylpyruvate, and certain catecholamines, suggesting that MIF might exert its biological effects via enzymatic action on a substrate. However, no physiologically relevant substrate for MIF has been identified. Site-directed mutagenesis studies have not consistently supported a requirement for an intact, functional catalytic site as a prerequisite for MIF bioactivity. We hypothesized that the catalytically active site, but not the enzymatic activity per se, nevertheless plays a critical role in MIF pro-inflammatory activity. Accordingly, we designed small druglike molecules that bind at the catalytically active tautomerase site of MIF and tested the complex for MIF bioactivity. We describe herein the rational design and synthesis of a class of imine conjugates produced by coupling amino acids to a range of benzaldehyde derivatives that inhibit MIF tautomerase and biological activities. We found that aromatic amino acid Schiff bases were better inhibitors of MIF enzymatic and bioactivities compared to the aliphatic ones. For instance, the IC(50) inhibition of MIF tautomerase activity by aromatic amino acid Schiff base methyl esters was achieved at a concentration between 1.65 and 50 microM, suggesting a critical role for the additional binding of the aromatic residues within the vicinity of the active site. The most potent inhibitor of MIF tautomerase activity was 2-[(4-hydroxybenzylidene)amino]-3-(1H-indol-3-yl)propionic acid methyl ester (8), with an IC(50) of 1.65 microM. We found that compound 8 binding to MIF active site resulted in the inhibition of MIF bioactivity in three established bioassays: ERK-1/2 MAP kinase activation, p53-dependent apoptosis, and proliferation of serum-starved cells. Compound 8 inhibited MIF interaction with its as yet unidentified cognate cell surface receptor as shown by flow cytometry, concluding a critical role for the tautomerase active site in receptor binding. Thus the inhibitory effect of compound 8 on MIF bioactivities strongly correlated with the inhibition of MIF tautomerase activity, a connection not made previously through use of small-molecule MIF inhibitors. The inhibitory activity of amino acid-benzaldehyde Schiff base-type MIF antagonists is the first step toward a meaningful structure/function analysis of inhibitors of MIF cellular bioactivities.

Colorectal cancer in inflammatory bowel disease: molecular and clinical features

The two forms of inflammatory bowel disease (IBD), Crohn's disease and ulcerative colitis, are characterized by chronic and relapsing inflammation of the intestines. Initiating events presumably occur well before patients are symptomatic. Evidence gathered over the past decade from both IBD patients and animal models of intestinal inflammation have confirmed that IBD represents complex heterogenic forms of diseases, influenced by a combination of environmental, genetic, and immunologic factors working in concert to produce exaggerated immune responses, resulting in chronic and remitting inflammation.

In vitro and in vivo regulation by macrophage migration inhibitory factor (MIF) of expression of MHC-II, costimulatory, adhesion, receptor, and cytokine molecules

The secretion of macrophage migration inhibitory factor (MIF) is enhanced by inflammatory and other stimuli. MIF regulates innate and adaptive immune responses, but the mechanisms of this regulation are poorly understood. Our hypothesis was that MIF generated by these stimuli regulates these responses by modulating key molecular expression. This hypothesis was tested by adding greater than constitutive concentrations of recombinant MIF to cultures of various cell types and flow cytometric assay. MIF modulated surface expression of MHC-II, B7-2, CD40, CD40 ligand, ICAM-1 and Fcgamma, CR1/CR2, and IL-10 receptors and intracellular expression of IL-10, TNFalpha, and p40 (IL-12). MIF increased expression of B7-1 by B cells and CD40 L by T cells in spleens from Schistosoma mansoni-infected mice. Footpad injection of MIF reduced expression of MHC-II and CD40 by B cells in draining lymph nodes. Footpad injection of Mab to MIF reduced expression of B7-2 and CR1/CR2 by B cells and B7-2 by macrophages in these nodes. These data support our hypothesis.

Inflammation and the development of pancreatic cancer

OBJECTIVE

Pancreatic cancer has an extremely poor prognosis and the cellular mechanisms contributing to pancreatic cancer are relatively unknown. The goals of this review are to present the epidemiological and experimental data that supports inflammation as a key mediator of pancreatic cancer development, to explain how inflammatory pathways may create an environment that supports tumor formation, and to discuss how the use of novel agents directed at these pathways may be used for the treatment of pancreatic malignancy.

SUMMARY BACKGROUND DATA

Inflammation has been identified as a significant factor in the development of other solid tumor malignancies. Both hereditary and sporadic forms of chronic pancreatitis are associated with an increased risk of developing pancreatic cancer. The combined increase in genomic damage and cellular proliferation, both of which are seen with inflammation, strongly favors malignant transformation of pancreatic cells. Cytokines, reactive oxygen species, and mediators of the inflammatory pathway (e.g., NF-kappaB and COX-2) have been shown to increase cell cycling, cause loss of tumor suppressor function, and stimulate oncogene expression; all of which may lead to pancreatic malignancy. Anti-cytokine vaccines, inhibitors of pro-inflammatory NF-kappaB and COX-2 pathways, thiazolidinediones, and anti-oxidants are potentially useful for the prevention or treatment of pancreatic cancer. Redirection of experimental interests toward pancreatic inflammation and mechanisms of carcinogenesis may identify other novel anti-inflammatory agents or other ways to screen for or prevent pancreatic cancer.

CONCLUSION

Pancreatic inflammation, mediated by cytokines, reactive oxygen species, and upregulated pro-inflammatory pathways, may play a key role in the early development of pancreatic malignancy.

A functional promoter polymorphism in the macrophage migration inhibitory factor (MIF) gene associated with disease severity in rheumatoid arthritis

The macrophage migration inhibitory factor (MIF) is a potent pro-inflammatory cytokine and regulates the anti-inflammator effects of glucocorticoids. An important role for MIF within the cytokine cascade is to act in concert with endogenous glucocorticoids to control the set-point and magnitude of the inflammatory response. Elevated expression of MIF in the circulation and in the synovial joint has been documented in rheumatoid arthritis. MIF also has been linked to the development of joint damage and disease pathology in experimental animal models. We describe herein a novel CATT-tetranucleotide repeat polymorphism at position -794 of the human Mif gene and show that it functionally affects the activity of the MIF promoter in gene reporter assays. We describe four genotypes which comprise 5, 6, 7, or 8-CATT repeat units and show that the 5-CATT allele has the lowest level of basal and stimulated MIF promoter activity in vitro. The presence of the low expressing, 5-CATT repeat allele correlated with low disease severity in a cohort of rheumatoid arthritis patients.

Macrophage migration inhibitory factor (MIF): mechanisms of action and role in disease

Macrophage migration inhibitory factor (MIF) is a unique cytokine and critical mediator of host defenses with a role in septic shock and chronic inflammatory and autoimmune diseases. Its mechanism of action is incompletely understood. Here, we attempt to correlate current knowledge on the molecular pathways of MIF activity with its functions in immunity and disease.

Response of serum macrophage migration inhibitory factor levels to stimulation or suppression of the hypothalamo-pituitary-adrenal axis in normal subjects and patients with Cushing's disease

Macrophage migration inhibitory factor (MIF) is a proinflammatory pituitary and immune cell cytokine and a critical mediator of septic shock. It has been reported that MIF is secreted in parallel with ACTH from the pituitary in response to stress or inflammatory stimuli. MIF release from immune cells is also induced rather than inhibited by glucocorticoids. It has therefore been suggested that MIF may be a novel counterregulatory hormone of glucocorticoid action that acts both as a paracrine and endocrine modulator of host responses. We have measured circulating MIF levels, using a human MIF ELISA, in normal subjects and patients under numerous pathophysiological conditions. Serum MIF was measured in normal subjects who underwent stimulation of the hypothalamo-pituitary-adrenal axis with an insulin tolerance test (n = 8), a CRH-stimulation test (n = 5), a short synacthen test (n = 5), and following a low-dose dexamethasone suppression test (n = 6). We also sampled from a peripheral vein and both inferior petrosal sinuses before and after CRH stimulation in four patients with a histologically proven diagnosis of Cushing's disease. Immunostaining of the pituitary tumors for MIF was also performed. In normal subjects serum MIF levels did not rise in parallel with cortisol during the insulin tolerance or CRH test or after administration of synthetic ACTH. In all subjects cortisol levels became undetectable after the low-dose dexamethasone suppression test, and no consistent change was observed in serum MIF levels during the test. In patients with Cushing's disease, there was no basal central-to-peripheral gradient in MIF, and no consistent changes occurred in serum MIF levels in either the left or right inferior petrosal sinus after CRH stimulation; however, immunostaining of the surgically removed pituitary tumors from the same patients showed strong staining for both ACTH and MIF. These results show that in humans acute modulation of the hypothalamo-pituitary-adrenal axis does not significantly alter circulating MIF levels. In addition, ACTH-secreting pituitary tumors that express MIF do not release MIF either spontaneously or in response to CRH stimulation, and there is no gradient for MIF in the venous drainage of the pituitary. Our study suggests that the pituitary gland is not the major contributor to circulating MIF; an autocrine or paracrine role for pituitary-derived MIF is more likely.

Expression of macrophage migration inhibitory factor in human breast cancer: association with nodal spread

Macrophage migration inhibitory factor (MIF) is known to exert pleiotropic functions including inhibition of macrophage migration, anchoring, and counteraction of the anti-inflammatory and immunosuppressive activity of glucocorticoids. Ninety-three primary breast cancer tissues and 64 sera of primary breast cancer patients were analyzed for the expression of MIF. The clinico-pathological significance of MIF expression was evaluated. It was found that MIF was frequently over-expressed in primary breast cancer tissues. RT-PCR and western blotting analysis confirmed that wild-type MIF is expressed, and immunohistochemical analysis showed that MIF expression was localized at tumor cells as well as stromal cells, including tumor-associated macrophages. Intratumoral MIF protein concentrations detected by enzyme-linked immunosorbent assay (ELISA) varied with a median value of 1821 ng/mg protein (range: 8 - 8126 ng/mg protein), and correlated inversely with nodal involvement (P = 0.039). No significant correlation was observed with other clinico-pathological factors including tumor size, menopausal status and hormone receptors. The circulating level of MIF protein ranged up to 105.7 ng/ml (median: 17.3 ng/ml), and it was also found to correlate inversely with the number of involved nodes (P = 0.02). A comparative study with other soluble inflammatory mediators showed that intratumoral levels of MIF were significantly associated with those of interleukin-1 beta, suggesting that interactions between tumor cells and tumor-associated macrophages play an important role in the up-regulation of MIF. The multifunctional inflammatory/immune mediator MIF was frequently expressed in primary breast cancer, and its expression level was inversely associated with nodal spread. Thus, MIF seems to play a role in tumor-stroma interactions of primary breast cancers, particularly those with a phenotype of node-negative or minimal nodal spread.

Receptor binding and cellular uptake studies of macrophage migration inhibitory factor (MIF): use of biologically active labeled MIF derivatives

Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine for which a receptor has not been identified. That MIF has intracellular functions has been suggested by its enzymatic activity and constitutive expression profile. The discovery of functional MIF-c-Jun activation domain binding protein 1 (JAB1) binding has confirmed this notion and indicated that nonreceptor-based signaling mechanisms are important for MIF function. Here, we have generated and tested several biologically active labeled MIF derivatives to further define target protein binding by MIF and its cellular uptake characteristics. (35)S-MIF, biotinylated MIF, and fluoresceinated MIF were demonstrated to exhibit full biologic activity. Neither by applying a standard iodinated MIF preparation nor by using the biologically active (35)S-MIF derivative in receptor-binding studies were we able to measure any receptor-binding activity on numerous cells, confirming that uptake of MIF into target cells and MIF signaling can occur by receptor-independent pathways. When MIF derivatives were applied in cellular uptake studies, MIF was found to be endocytosed into both immune and nonimmune cells and targeted to the cytosol and lysosomes. The entry of MIF was temperature and energy dependent and was inhibited by monodansylcadaverine but not by ouabain. Endocytosed biotin-MIF bound JAB1 not only in macrophages, as shown previously, but also in nonimmune cells. A tagged MIF construct, MIF-enhanced green fluorescent protein (EGFP), was shown to be a valuable tool, as EGFP constructs of critical MIF cysteine mutants exhibited identical cellular localization properties to those of wild-type MIF (wtMIF). Our results indicate that MIF membrane receptors are not widely expressed, if at all, and suggest that the cellular uptake of MIF occurs by nonreceptor-mediated endocytosis rather than penetration. All the derivatives investigated, except for iodinated MIF, represent valuable tools for further MIF target protein and cellular studies.

Ubiquitous production of macrophage migration inhibitory factor by human gastric and intestinal epithelium

BACKGROUND & AIMS

Macrophage migration inhibitory factor (MIF) inhibits macrophage migration and has pleiotropic activities on immune and inflammatory responses, cell growth, and glucose metabolism. MIF is produced by T cells, macrophages, and endothelial cells. Because intestinal epithelial cells produce mediators important for regulating mucosal immune and inflammatory responses, we sought to determine if these cells produce MIF.

METHODS

MIF expression was determined by immunostaining of human intestinal mucosa, intestinal xenografts, and cultured cells. MIF protein levels were quantitated by enzyme-linked immunosorbent assay and immunoblot analysis, messenger RNA was assessed by real-time reverse-transcription polymerase chain reaction, and functional activity was assessed by enzymatic and migration assays.

RESULTS

MIF was abundantly expressed in vivo in gastric, small intestinal, and colonic epithelium and in epithelium lining human intestinal xenografts. MIF was also constitutively expressed at the messenger RNA and protein level by several cultured colon and gastric epithelial cell lines, and its expression in those cells was not up-regulated by the proinflammatory cytokines interleukin 1alpha, tumor necrosis factor alpha, or interferon gamma. Epithelial MIF from cultured cells was released predominantly from the apical side after Salmonella infection, had tautomerase activity, and arrested macrophage migration.

CONCLUSIONS

Human intestinal epithelial cells are a major source of MIF, a molecule that can regulate macrophage migration, inflammation, and cell metabolism.

Intra-tumoral interleukin-6 down-regulation system and genetic mutations of tumor suppressor genes in colorectal carcinoma

BACKGROUND

The interleukin (IL)-1-IL-6 network, the most potent cascade of pro-inflammatory cytokines, plays an autocrine role in tumor growth. The IL-1-IL-6 network is down-regulated by a phased cytokine inhibitor IL-1 receptor antagonist (ra) and an anti-inflammatory cytokine IL-10. The current study evaluated this down-regulation system in colorectal carcinoma and its relation to the genetic alteration of tumor suppressor genes.

METHODS

Seventy-four specimens of primary colorectal carcinoma and normal mucosa were collected to measure tissue concentrations of cytokines. Polymerase chain reaction amplification was performed to investigate the loss of heterozygosity of the microsatellite markers on chromosomes 17p and 18q.

RESULTS

The IL-1ra/IL-6 ratio in the carcinoma specimens was lower than ratios in adenomas and normal mucosae and decreased with disease progression. The IL-1ra/IL-6 ratio in early cancers tended to be lower than that in adenomas and normal mucosae. However, the tissue concentrations of IL-1beta and IL-10 were not associated with any clinicopathologic parameters. The tissue IL-1ra concentration correlated with that of IL-6 only in adenomas and early cancers. Immunohistochemically, IL-1ra and IL-6 were localized in the tumor cytoplasm. A reduced tissue IL-1ra/IL-6 ratio in the carcinomas correlated with poor prognosis and was associated with the loss of heterozygosity of the microsatellite markers on chromosomes 18q.

CONCLUSIONS

There is an IL-6-IL-1ra network system in colorectal tumors, but this system deteriorates with carcinogenesis and tumor growth. The deterioration of this network system was associated with the allelic loss of a portion of chromosome 18q, reflecting the genetic alteration of tumor suppressor genes.

Influence of the mucosal epithelium microenvironment on Langerhans cells: implications for the development of squamous intraepithelial lesions of the cervix

We have addressed the notion that the initiation and progression of human papillomavirus associated cancer of the uterine cervix are associated with alterations of Langerhans cells (LC) within the mucosal squamous epithelium. Since the transformation zone (TZ) of the cervix is the site where the majority of squamous intraepithelial lesions (SIL) are initiated, in contrast to the exocervix, we decided to investigate the influence of the local microenvironment within the TZ on the function and density of LC. We show that the TZ is associated with a significant reduction in the density of immature LC (CD1a/LAG) compared to the exocervix. In contrast, the development of SILs is attributed with a relative increased density of immature LC, compared to the TZ. Furthermore, we show that this variability in LC density is correlated with a differential expression of TNFalpha and MIP3alpha within the micro-environment of the TZ and SILs. Both TZ and SIL epithelium-derived LC, in the presence of allogeneic PBMC, induced lower levels of proliferation and IL2 production and higher levels of the immunosuppressive cytokine IL10 in comparison to the exocervix. Nevertheless, the epithelium-derived LC in SILs exhibits a reduction in their functional activity, relative to the TZ. Together our studies suggest that the immunosurveillance within the epithelium of the TZ may be intrinsically perturbed due to the altered expression of chemokines/cytokines and the concomitant diminished density of LC. Furthermore, following HPV infection and the development of SILs, the function of LC may be further incapacitated by viral associated mechanisms.

Tumor necrosis factor alpha stimulates invasion of Src-activated intestinal cells

BACKGROUND & AIMS

Src activation is correlated with progression of colorectal cancer (CRC). CRCs accompanied by ulcerative colitis, chronic inflammation in the colon, often have elevated Src activity, and ulcerative colitis-related CRCs are more likely to become invasive, whereas Ras activation is rarely associated with this disease. The aim of this study was to investigate the effects of a proinflammatory cytokine, tumor necrosis factor alpha (TNF-alpha), on the invasive properties of epithelial cells constitutively expressing activated Ras or Src.

METHODS

A cell line derived from intestinal epithelia was transfected with a v-src- or v-H-ras-expressing vector. The effect of TNF-alpha on morphologic changes in colonies cultured in soft agar was determined. Src protein kinase activity, peroxide production, E-cadherin expression levels, and the phosphorylation status of beta-catenin and E-cadherin were determined. The invasive potential of these cells was determined by measuring cell motility and using an in vitro invasion assay.

RESULTS

TNF-alpha altered the colony morphology of src-, but not ras-expressing cells. TNF-alpha increased peroxide production, leading to Src protein expression as well as Src activity in src transfectants. Activation of Src by TNF-alpha led to reduced E-cadherin levels and enhanced invasion of src transfectants. Pyrrolidine dithiocarbamate and herbimycin A inhibited these effects.

CONCLUSION

These results indicate that Src kinase activation enhances the response of epithelial cells to TNF-alpha leading to increased invasion through mechanisms that involve production of reactive oxygen intermediates.

Macrophage migration inhibitory factor (MIF) sustains macrophage proinflammatory function by inhibiting p53: regulatory role in the innate immune response

The importance of the macrophage in innate immunity is underscored by its secretion of an array of powerful immunoregulatory and effector molecules. We report herein that macrophage migration inhibitory factor (MIF), a product of activated macrophages, sustains macrophage survival and function by suppressing activation-induced, p53-dependent apoptosis. Endotoxin administration to MIF(-/-) mice results in decreased macrophage viability, decreased proinflammatory function, and increased apoptosis when compared with wild-type controls. Moreover, inhibition of p53 in endotoxin-treated, MIF-deficient macrophages suppresses enhanced apoptosis and restores proinflammatory function. MIF inhibits p53 activity in macrophages via an autocrine regulatory pathway, resulting in a decrease in cellular p53 accumulation and subsequent function. Inhibition of p53 by MIF coincides with the induction of arachidonic acid metabolism and cyclooxygenase-2 (Cox-2) expression, which is required for MIF regulation of p53. MIF's effect on macrophage viability and survival provides a previously unrecognized mechanism to explain its critical proinflammatory action in conditions such as sepsis, and suggests new approaches for the modulation of innate immune responses.

Inhibition of macrophage migration inhibitory factor (MIF) tautomerase and biological activities by acetaminophen metabolites

The cytokine macrophage migration inhibitory factor (MIF) has emerged to be an important regulator of the inflammatory response and is critically involved in the development of septic shock, arthritis, and glomerulonephritis. Although the biological activities of MIF are presumed to require a receptor-based mechanism of action, the protein is also a tautomerase and has a catalytically active N-terminal proline that is invariant in structurally homologous bacterial isomerases. This observation raises the possibility that MIF may exert its biological action via an enzymatic reaction. Physiologically relevant substrates for MIF have not been identified, nor have site-directed mutagenesis studies consistently supported the requirement for a functional catalytic site. Small molecule inhibitors of MIF's isomerase activity also have been developed, but none have been shown yet to inhibit MIF biological activity. We report herein that the iminoquinone metabolite of acetaminophen, N-acetyl-p-benzoquinone imine (NAPQI), inhibits both the isomerase and the biological activities of MIF. The reaction between NAPQI and MIF is covalent and produces a NAPQI-modified MIF species with diminished cell binding activity and decreased recognition by anti-MIF mAb. These data are consistent with a model by which the NAPQI reacts with the catalytic Pro-1 of MIF to disrupt the integrity of epitope(s) critical to MIF's biological activity and point to the importance of the catalytic domain, but not the catalytic activity per se, in MIF function. These results also point to a powerful approach for the design of small molecule inhibitors of MIF based on interaction with its catalytic site and constitute an example of a pharmacophore capable of irreversibly inhibiting the action of a proinflammatory cytokine.

Human herpesvirus-8 and Kaposi's sarcoma: relationship with the multistep concept of tumorigenesis

Kaposi's sarcoma (KS) develops through discrete inflammatory-angiogenic stages of polyclonal nature (early-stage lesions) to monomorphic nodules of spindle-shaped cells that can be clonal (late-stage lesions) and resemble true sarcomas. Molecular and epidemiological studies indicate that development of KS is tightly associated with infection by the human herpesvirus-8 (HHV-8). However, only individuals with specific conditions of immunodysregulation develop KS. In these individuals the systemic and tissue increase of Th-1-type cytokines (IC) reactivate HHV-8 infection, leading to increased viral load, antibody titers, and an expanded cell tropism that precedes the clinical appearance of KS. Recruitment of the virus into tissues by infected monocytes and other cell types is facilitated by the endothelial cell activation due to IC. In clinical lesions, HHV-8 infection increases with lesion stage and in late-stage lesions most of the spindle cells are latently infected, whereas only few lyrically infected cells are present, suggesting that latent genes may have a role in the transformation of the early inflammatory-hyperplastic lesion into a real sarcoma. The development of tumors, however, is regulated through a multistep process based on the acquisition by cells of several different capabilities leading to malignant growth. Here we review the available data on the expression of HHV-8-encoded genes in primary KS lesions and, in view of their biological activity, analyze their potential function in different steps of tumorigenesis. By this pragmatic approach interesting insights into potential key functions of HHV-8-encoded genes are found and steps of potential cooperativity with other viral factors (HIV-1-Tat) in the pathogenesis of KS are identified.