Regulation of Integrin Activity by MIA

From mice to men: An assessment of preclinical model systems for the study of vitiligo

Vitiligo is an autoimmune skin disease of multiple etiology, for which there is no complete cure. This chronic depigmentation is characterized by epidermal melanocyte loss, and causes disfigurement and significant psychosocial distress. Mouse models have been extensively employed to further our understanding of complex disease mechanisms in vitiligo, as well as to provide a preclinical platform for clinical interventional research on potential treatment strategies in humans. The current mouse models can be categorized into three groups: spontaneous mouse models, induced mouse models, and transgenic mice. Despite their limitations, these models allow us to understand the pathology processes of vitiligo at molecule, cell, tissue, organ, and system levels, and have been used to test prospective drugs. In this review, we comprehensively evaluate existing murine systems of vitiligo and elucidate their respective characteristics, aiming to offer a panorama for researchers to select the appropriate mouse models for their study.

A Systematic Compilation of Human SH3 Domains: A Versatile Superfamily in Cellular Signaling

SRC homology 3 (SH3) domains are fundamental modules that enable the assembly of protein complexes through physical interactions with a pool of proline-rich/noncanonical motifs from partner proteins. They are widely studied modular building blocks across all five kingdoms of life and viruses, mediating various biological processes. The SH3 domains are also implicated in the development of human diseases, such as cancer, leukemia, osteoporosis, Alzheimer's disease, and various infections. A database search of the human proteome reveals the existence of 298 SH3 domains in 221 SH3 domain-containing proteins (SH3DCPs), ranging from 13 to 720 kilodaltons. A phylogenetic analysis of human SH3DCPs based on their multi-domain architecture seems to be the most practical way to classify them functionally, with regard to various physiological pathways. This review further summarizes the achievements made in the classification of SH3 domain functions, their binding specificity, and their significance for various diseases when exploiting SH3 protein modular interactions as drug targets.

Efficacy of a topical formulation containing MIA (Melanoma Inhibitory Activity) - Inhibitory peptides in a case of recalcitrant vitiligo in combination with UV exposure

INTRODUCTION

Vitiligo is an acquired chronic pigmentation disorder of the skin. Even if the role of the immune system seems to be well established, new pathogenetic hypothesis are rising in these years. It has been recently suggested by the development of an animal model that a protein called Melanoma Inhibitory Activity (MIA) is involved in the pathogenesis of vitiligo. This protein interacts with the adhesion molecules expressed on the melanocytes causing its detachment from extracellular matrix proteins and creating the depigmented macules. A topical preparation based on oligopeptides able to inhibit the actions of the MIA protein has been introduced to the market, claiming activity on vitiligo.

PATIENT CONCERNS AND DIAGNOSIS

A patient affected by non-segmental vitiligo for 10 years, recalcitrant to any treatment (such as steroids, immunomodulators, kellin, UVB-NB and UVA) came to our observation.

INTERVENTIONS

We used this topical preparation containing the MIA inhibitors peptides in selected areas (face and sides of the trunk) leaving untreated other areas as control (legs and arms). The patient was required to be sun exposed or to have some UVA sessions during the treatment to stimulate the melanocytes replications.

OUTCOMES

After 9 months of treatments, he recovered from 50% to 80% of repigmentation only in the treated areas, without any side effects locally or systemically.

CONCLUSION

Even if other studies are required to better determine the efficacy of this approach, this first observation about the use of the MIA-inhibitors peptides for the treatment of non-segmental vitiligo indicates that this topical preparation containing the MIA inhibitors peptides could be a very promising option for the cure of this disease.

Melanoma Inhibitory Activity (MIA) Is Able to Induce Vitiligo-Like Depigmentation in an in vivo Mouse Model by Direct Injection in the Tail

In the complex pathogenesis of vitiligo, the exact mechanism of the dermatosis is still to be clarified. We previously demonstrated that a protein called melanoma inhibitory activity (MIA) is present in non-segmental vitiligo skin and seems to cause the detachment of melanocytes, consequently creating the depigmented macules. In this study, we present an animal model of vitiligo on the basis of the ability of the MIA protein to induce vitiligo-like lesions. Twenty pigmented mice were chosen for the experiments and received injections in the tail with saline (control group) or with saline + MIA protein (treated group). The control group did not show any sign of depigmentation. The treated group showed, instead, clear zones of complete depigmentation in the injected areas in each mouse, with the appearance of white patches with whitening of the hair and a clear-cut edge. Histological examination of the tail in the treated zone showed the absence of melanocytes, without the presence of any inflammatory cell or any sign of skin inflammation patterns, confirming the detachment of the melanocyte operated by the MIA protein. These data seem to confirm a possible role played by the MIA protein in the pathogenesis of vitiligo and may support the development of treatments able to inhibit its action as an alternative therapeutic strategy for this disorder.

Mast cell chymase promotes angiogenesis and lymphangiogenesis mediated by activation of melanoma inhibitory activity gene family members in oral squamous cell carcinoma

Mast cells (MCs) are present in the tumor stroma, and MCs that express the mast cell‑specific proteases tryptase and chymase (MCTC) exhibit several tumor‑related functions. It was previously reported that melanoma inhibitory activity (MIA) gene family members, including MIA, MIA2, and transport and Golgi organization protein 1 (TANGO), possess oncogenic functions in oral squamous cell carcinoma (OSCC). However, the relationships between MCTC, and clinicopathological characteristics and activation of the MIA gene family in OSCC remain unknown. In the present study, the functional roles of MCTC in patients with OSCC were investigated using immunohistochemistry and reverse transcription‑quantitative PCR. In addition, the effects of extracellular chymase on oral cancer cells were examined. In patients with OSCC, MCTC density was significantly affected by tumor progression and nodal metastasis, and was correlated with vessel density. MCTC density was also correlated with MIA and MIA2 expression. In OSCC cells, extracellular chymase promoted the secretion of vascular endothelial growth factor family proteins, and the transmigration and adhesion of HSC3 cells to endothelial cells; knockdown of MIA, MIA2 and TANGO attenuated these effects. The present findings indicated that MCTC act as tumor‑progressive factors in OSCC via the activation and secretion of MIA and MIA2, and the induction of angiogenesis and lymphangiogenesis.

Role of melanoma inhibitory activity in melanocyte senescence

The protein melanoma inhibitory activity (MIA) is known to be expressed in melanoma and to support melanoma progression. Interestingly, previous studies also observed the expression of MIA in nevi. Concentrating on these findings, we revealed that MIA expression is correlated with a senescent state in melanocytes. Induction of replicative or oncogene-induced senescence resulted in increased MIA expression in vitro. Notably, MIA knockdown in senescent melanocytes reduced the percentage of senescence-associated beta-Gal-positive cells and enhanced proliferation. Using the melanoma mouse model Tg(Grm1), MIA-deficient mice supported the impact of MIA on senescence by showing a significantly earlier tumor onset compared to controls. In melanocytes, MIA knockdown led to a downregulation of the cell cycle inhibitor p21 in vitro and in vivo. In contrast, after induction of hTERT in human melanoma cells, p21 regulation by MIA was lost. In summary, our data show for the first time that MIA is a regulator of cellular senescence in human and murine melanocytes.

The importance of melanoma inhibitory activity gene family in the tumor progression of oral cancer

Oral squamous cell carcinoma has a high potential for locoregional invasion and nodal metastasis. Consequently, early detection of such malignancies is of immense importance. The melanoma inhibitory activity (MIA) gene family comprises MIA, MIA2, transport and Golgi organization protein 1 (TANGO), and otoraplin (OTOR). These members of the MIA gene family have a highly conserved Src homology 3 (SH3)-like structure. Although the molecules of this family share 34-45% amino acid homology and 47-59% cDNA sequence homology, those members, excluding OTOR, play different tumor-associated functions. MIA has a pivotal role in the progression and metastasis of melanoma; MIA2 and TANGO have been suggested to possess tumor-suppressive functions; and OTOR is uniquely expressed in cochlea of the inner ear. Therefore, the definite functions of the MIA gene family in cancer cells remain unclear. Since the members of the MIA gene family are secreted proteins, these molecules might be useful tumor markers that can be detected in the body fluids, including serum and saliva. In this review, we described the molecular biological functions of the MIA gene family in oral cancer.

A comprehensive expression analysis of the MIA gene family in malignancies: MIA gene family members are novel, useful markers of esophageal, lung, and cervical squamous cell carcinoma

Melanoma inhibitory activity (MIA) gene family members include MIA, MIA2, and Transport and Golgi organization protein 1 (TANGO). Although MIA gene family members have several tumor-related functions, their detailed roles in malignancies remain poorly elucidated. In this study, 477 tumor specimens were subjected to immunohistochemical screening to evaluate MIA gene family expression. For a validation analysis, we also examined the association between MIA gene family expression and clinicopathological factors in 66 cases of esophageal cancer, 145 cases of lung cancer, and 126 cases of cervical cancer. The frequency of MIA gene family expression was higher among squamous cell carcinomas than among other tumor types subjected to screening. In the validation analysis, MIA gene family staining was observed frequently in esophageal and lung cancers associated with nodal and/or distant metastasis. In cervical cancers, MIA and TANGO immunostaining also correlated with tumor progression and metastasis. Furthermore, MIA2 expression levels in invasive cervical cancer were upregulated relative to those in cervical intraepithelial neoplasia 3. A disease-free survival analysis revealed that MIA-, MIA2, or TANGO-positive patients had a significantly shorter disease-free survival than did those patients who were negative. Our results suggest that MIA, MIA2, and TANGO may be useful diagnostic and therapeutic molecular targets in human malignancies.

Storkhead box 2 and melanoma inhibitory activity promote oral squamous cell carcinoma progression

Background

Storkhead box protein 2 (STOX2) is a transcriptional factor associated with pre-eclampsia with fetal growth restriction. We recently reported that melanoma inhibitory activity (MIA) promotes oral squamous cell carcinoma (OSCC) progression. However, the relationship between STOX2 and MIA remains unknown in malignancies.

Methods

We used immunohistochemistry and PCR to investigate MIA and STOX2 expression in OSCC. We also performed functional analysis in human OSCC cells.

Results

MIA and STOX2 mRNA levels were higher in OSCCs than in normal oral epithelial cells, and upregulation of STOX2 was significantly correlated with overexpression of MIA. Immunostaining for STOX2 was associated with nodal metastasis (P = 0.0002) and MIA expression (P < 0.0001). Furthermore, MIA expression (P = 0.0035) and STOX2 expression (P = 0.0061) were associated with poor outcome in OSCCs. In vitro analysis using OSCC cells revealed that MIA increased expression of STOX2 by paracrine manner. Moreover, STOX2 accelerated OSCC cell growth, invasion, suppressed apoptosis, and enhanced resistance to paclitaxel, cisplatin, and 5-FU.

Conclusions

Our results suggest that MIA-STOX2 signaling may be a useful diagnostic and therapeutic target in OSCCs.

Circulating biomarkers in malignant melanoma

Melanoma is an aggressive tumor with increasing incidence worldwide. Biomarkers are valuable tools to minimize the cost and improve efficacy of treatment of this deadly disease. Serological markers have not widely been introduced in routine clinical practice due to their insufficient diagnostic sensitivity and specificity. It is likely that the lack of objective responses with traditional treatment hinder biomarker research and development in melanoma. Recently, new drugs and therapies have, however, emerged in advanced melanoma with noticeable objective response ratio and survival. In this new scenario, serological tumor markers should be revisited. In addition, other potential circulating biomarkers such as cell-free DNA, exosomes, microRNA, and circulating tumor cells have also been identified. In this review, we summarize classical and emerging tumor markers and discuss their possible roles in emerging therapeutics.

Melanoma inhibitory activity in melanoma diagnostics and therapy - a small protein is looming large

Malignant melanoma is a highly aggressive cancer with a very poor prognosis after the onset of metastasis. We have previously demonstrated that the protein melanoma inhibitory activity (MIA) is involved in the metastasis of and immunosuppression in malignant melanoma. Recently, we further established MIA as a therapeutic target to inhibit metastatic spread in malignant melanoma. We could show that an inhibition of MIA by a synthetic peptide decreased both the number of metastases as well as immunosuppression in a murine model of malignant melanoma. To control recurrence after surgical resection of a primary lesion, it is paramount to have diagnostic tools available that can detect a relapse due to the strong metastatic potential of melanoma. This follow-up is maintained with periodic re-examinations. Due to high cost and the associated radiation exposure, radiology examinations are avoided if possible. The analysis of prognostic markers in patient serum is therefore attractive. In this review, we focus on the quantitative analysis of the MIA protein as a prognostic tool because it has proven to be a useful serum marker for documenting disease progression of malignant melanoma. The MIA quantification assay itself is readily performed using an ELISA kit and common laboratory equipment. Because analysing MIA serum levels in combination with other established markers such as S100B improves their prognostic value, we feel that the quantification of MIA in the serum, among other markers, should be performed as a general standard of care in patients at risk of developing metastatic melanoma.

The cartilage protein melanoma inhibitory activity contributes to inflammatory arthritis

OBJECTIVE

Melanoma inhibitory activity (MIA) is a small chondrocyte-specific protein with unknown function. MIA knockout mice (MIA(-/-)) have a normal phenotype with minor microarchitectural alterations of cartilage. Our previous study demonstrated that immunodominant epitopes of MIA are actively presented in an HLA-DR4-restricted manner in the inflamed RA joint. The objective of this study was to investigate the potential role of MIA as an autoantigen.

METHODS

Collagen-induced arthritis (CIA) and anti-collagen antibody-induced arthritis (CAIA) were induced in MIA(-/-) mice. Anti-type II collagen (anti-CII) antibodies were measured by ELISA. T cell proliferation and cytokine production were assessed by flow cytometry.

RESULTS

MIA(-/-) mice had a markedly reduced incidence and severity of CIA and CAIA compared with wild-type (WT) mice. Attenuation of disease was not related to defective binding of anti-CII antibodies to cartilage in the absence of MIA. However, MIA(-/-) mice had significantly reduced anti-CII IgG1 and IgG2a antibody levels accompanied by an increase in FoxP3-expressing CD25(+)CD4(+) regulatory T cells. This was paralleled by a significant reduction in CII-specific IFN-γ production by T cells in MIA(-/-) but not WT animals, suggesting a qualitative impact of MIA on the collagen-induced Th1 response. Furthermore, Ag-specific proliferation of T cells after restimulation with MIA in WT but not MIA(-/-) mice indicated the existence of MIA-specific T cells in the context of CIA.

CONCLUSION

These data support a role for MIA as an autoantigen during arthritis development. Whether MIA can influence the balance of pathogenic vs regulatory responses in human RA remains to be investigated.

Roles of ion transport in control of cell motility

Cell motility is an essential feature of life. It is essential for reproduction, propagation, embryonic development, and healing processes such as wound closure and a successful immune defense. If out of control, cell motility can become life-threatening as, for example, in metastasis or autoimmune diseases. Regardless of whether ciliary/flagellar or amoeboid movement, controlled motility always requires a concerted action of ion channels and transporters, cytoskeletal elements, and signaling cascades. Ion transport across the plasma membrane contributes to cell motility by affecting the membrane potential and voltage-sensitive ion channels, by inducing local volume changes with the help of aquaporins and by modulating cytosolic Ca(2+) and H(+) concentrations. Voltage-sensitive ion channels serve as voltage detectors in electric fields thus enabling galvanotaxis; local swelling facilitates the outgrowth of protrusions at the leading edge while local shrinkage accompanies the retraction of the cell rear; the cytosolic Ca(2+) concentration exerts its main effect on cytoskeletal dynamics via motor proteins such as myosin or dynein; and both, the intracellular and the extracellular H(+) concentration modulate cell migration and adhesion by tuning the activity of enzymes and signaling molecules in the cytosol as well as the activation state of adhesion molecules at the cell surface. In addition to the actual process of ion transport, both, channels and transporters contribute to cell migration by being part of focal adhesion complexes and/or physically interacting with components of the cytoskeleton. The present article provides an overview of how the numerous ion-transport mechanisms contribute to the various modes of cell motility.

Melanoma inhibitory activity promotes melanoma development through activation of YBX1

Melanoma inhibitory activity (MIA), a small soluble secreted protein, is functionally important for progression of malignant melanoma. We recently revealed that p54(nrb) acts as a mediator of MIA action. In this study, we characterize the transcriptional regulation of p54(nrb) by MIA to explain MIA's molecular action. We identified one highly conserved region in the p54(nrb) promoter that is necessary and sufficient for MIA-dependent activation. Functional promoter analysis identified the transcription factor YBX1 as the mediator of MIA activation of p54(nrb) transcription. We screened the genome for further potential MIA-regulated genes carrying the element in their promoter regions. Integrating our sequence data with expression data from human melanomas identified a list of 23 potential MIA-YBX1 targets in melanomas. In summary, we present for the first time effects of MIA on transcriptional regulation. Uncovering new potential downstream effectors working via activation of YBX1 supports the important role of MIA in melanoma.

Protumoral roles of melanoma inhibitory activity 2 in oral squamous cell carcinoma

BACKGROUND

The role of melanoma inhibitory activity 2 (MIA2) was examined in human oral squamous cell carcinoma (OSCC).

METHODS

MIA2 role was examined by immunohistochemistry of human OSCCs and knockdown studies using human 3 OSCC cell lines with MIA2 expression.

RESULTS

MIA2 expression was observed in 62 (66.7%) of 93 OSCCs and was associated with tumour expansion and nodal metastasis. Melanoma inhibitory activity 2 expression was inversely correlated with intratumoral infiltration of lymphocytes. Invasion and anti-apoptotic survival were reduced by MIA2 knockdown in HSC3 cells. MOLT-3 lymphocytes infiltrating the HSC3 cell layer was enhanced by MIA2 knockdown or MIA2 depletion with the antibody. In HSC3 cells, MIA2 knockdown decreased the expressions of vascular endothelial growth factor (VEGF), VEGF-C, and VEGF-D. The downregulation of VEGF-C and -D was caused by inhibition of p38 and extracellular signal-regulated kinase (ERK)1/2, respectively. Melanoma inhibitory activity 2 was co-precipitated with integrin α4 andα5 in HSC3 cells. Integrin α4 knockdown decreased p38 phosphorylation and increased apoptosis, whereas integrin α5 knockdown decreased c-Jun N-terminal kinase (JNK) phosphorylation and apoptosis. Inhibition of JNK decreased apoptosis in the HSC3 cells.

CONCLUSION

These findings suggest that the roles of MIA2 might be based on the variety of the integrins and the subtypes of mitogen-activated protein kinase.

Role of ion channels and transporters in cell migration

Cell motility is central to tissue homeostasis in health and disease, and there is hardly any cell in the body that is not motile at a given point in its life cycle. Important physiological processes intimately related to the ability of the respective cells to migrate include embryogenesis, immune defense, angiogenesis, and wound healing. On the other side, migration is associated with life-threatening pathologies such as tumor metastases and atherosclerosis. Research from the last ≈ 15 years revealed that ion channels and transporters are indispensable components of the cellular migration apparatus. After presenting general principles by which transport proteins affect cell migration, we will discuss systematically the role of channels and transporters involved in cell migration.

Blood biomarkers for uveal melanoma

Uveal melanoma disseminates hematogenously, and blood biomarkers may be useful for prognosis and for monitoring disease progression. Melanoma-associated, metastatic and immune factors have been measured in the blood of patients with uveal melanoma, as have circulating melanoma cells. Most of the biomarkers were derived from studies in cutaneous melanoma. For various biological and/or technical reasons, these assessments have not demonstrated the accuracy required for effective prognostic or monitoring assays. Advances in uveal melanoma genomics and proteomics have generated many candidate biomarkers that are potentially measurable in blood. Measuring circulating nucleic acids may also be possible. Improvements in molecular profiling techniques that accurately predict metastatic risk in uveal melanoma patients should facilitate biomarker discovery and aid implementation in clinical testing. The stage is set to translate the advances made in understanding the molecular characteristics of uveal melanoma in order to identify and test clinically useful blood biomarkers of tumor dissemination and/or progression.

MIA is a potential biomarker for tumour load in neurofibromatosis type 1

BACKGROUND

Neurofibromatosis type 1 (NF1) is a frequent genetic disease characterized by multiple benign tumours with increased risk for malignancy. There is currently no biomarker for tumour load in NF1 patients.

METHODS

In situ hybridization and quantitative real-time polymerase reaction were applied to investigate expression of cartilage-specific genes in mice bearing conditional inactivation of NF1 in the developing limbs. These mice do not develop tumours but recapitulate aspects of NF1 bone dysplasia, including deregulation of cartilage differentiation. It has been recently shown that NF1 tumours require for their growth the master regulator of cartilage differentiation SOX9. We thus hypothesized that some of the cartilage-specific genes deregulated in an Nf1Prx1 mouse model might prove to be relevant biomarkers of NF1 tumours. We tested this hypothesis by analyzing expression of the SOX9 target gene product melanoma-inhibitory activity/cd-rap (MIA) in tumour and serum samples of NF1 patients.

RESULTS

Increased expression of Mia was found in Nf1-deficient cartilage in mice. In humans, MIA was expressed in all NF1-related tumours and its serum levels were significantly higher in NF1 patients than in healthy controls. Among NF1 patients, MIA serum levels were significantly higher in those with plexiform neurofibromas and in those with large number of cutaneous (> 1,000) or subcutaneous (> 100) neurofibromas than in patients without such tumours. Most notably, MIA serum levels correlated significantly with internal tumour burden.

CONCLUSIONS

MIA is a potential serum biomarker of tumour load in NF1 patients which could be useful in following the disease course and monitoring the efficacy of therapies.

Enhanced cartilage regeneration in MIA/CD-RAP deficient mice

Melanoma inhibitory activity/cartilage-derived retinoic acid-sensitive protein (MIA/CD-RAP) is a small soluble protein secreted from chondrocytes. It was identified as the prototype of a family of extracellular proteins adopting an SH3 domain-like fold. In order to study the consequences of MIA/CD-RAP deficiency in detail we used mice with a targeted gene disruption of MIA/CD-RAP (MIA−/−) and analyzed cartilage organisation and differentiation in in vivo and in vitro models. Cartilage formation and regeneration was determined in models for osteoarthritis and fracture healing in vivo, in addition to in vitro studies using mesenchymal stem cells of MIA−/− mice. Interestingly, our data suggest enhanced chondrocytic regeneration in the MIA−/− mice, modulated by enhanced proliferation and delayed differentiation. Expression analysis of cartilage tissue derived from MIA−/− mice revealed strong downregulation of nuclear RNA-binding protein 54-kDa (p54^nrb), a recently described modulator of Sox9 activity. In this study, we present p54^nrb as a mediator of MIA/CD-RAP to promote chondrogenesis. Taken together, our data indicate that MIA/CD-RAP is required for differentiation in cartilage potentially by regulating signaling processes during differentiation.

Modulation of cartilage differentiation by melanoma inhibiting activity/cartilage-derived retinoic acid-sensitive protein (MIA/CD-RAP)

Melanoma inhibiting activity/cartilage-derived retinoic acid-sensitive protein (MIA/CD-RAP) is a small soluble protein secreted from malignant melanoma cells and from chondrocytes. Recently, we revealed that MIA/CD-RAP can modulate bone morphogenetic protein (BMP)2-induced osteogenic differentiation into a chondrogenic direction. In the current study we aimed to find the molecular details of this MIA/CD-RAP function. Direct influence of MIA on BMP2 by protein-protein-interaction or modulating SMAD signaling was ruled out experimentally. Instead, we revealed inhibition of ERK signaling by MIA/CD-RAP. This inhibition is regulated via binding of MIA/CD-RAP to integrin alpha5 and abolishing its activity. Active ERK signaling is known to block chondrogenic differentiation and we revealed induction of aggrecan expression in chondrocytes by treatment with MIA/CD-RAP or PD098059, an ERK inhibitor. In in vivo models we could support the role of MIA/CD-RAP in influencing osteogenic differentiation negatively. Further, MIA/CD-RAP-deficient mice revealed an enhanced calcified cartilage layer of the articular cartilage of the knee joint and disordered arrangement of chondrocytes. Taken together, our data indicate that MIA/CD-RAP stabilizes cartilage differentiation and inhibits differentiation into bone potentially by regulating signaling processes during differentiation.

Celastrol acts as a potent antimetastatic agent targeting beta1 integrin and inhibiting cell-extracellular matrix adhesion, in part via the p38 mitogen-activated protein kinase pathway

Malignant tumors remain a significant health threat, with death often occurring as a result of metastasis. Cell adhesion is a crucial step in the metastatic cascade of tumor cells, and interruption of this step is considered to be a logical strategy for prevention and treatment of tumor metastasis. Celastrol [3-hydroxy-24-nor-2-oxo-1(10),3,5,7-friedelatetraen-29-oic acid], a quinone methide triterpene from the medicinal plant Tripterygium wilfordii, possesses antitumor activities, whereas the underlying mechanism(s) remains elusive. Here, we found that celastrol inhibited cell-extracellular matrix (ECM) adhesion of human lung cancer 95-D and mouse melanoma B16F10 cells. This inhibition was achieved through suppressing beta1 integrin ligand affinity and focal adhesion formation, accompanied by the reduced phosphorylation of focal adhesion kinase (FAK). In understanding the underlying mechanisms, we found that celastrol activated p38 mitogen-activated protein kinase (MAPK) by phosphorylation before the decrement of phosphorylated FAK and that this action was independent of the presence of fibronectin. Using 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB203580), a specific inhibitor of p38 MAPK, the effects of celastrol on beta1 integrin function, cell-ECM adhesion, and phosphorylation of FAK were partially attenuated. In addition, focal adhesion-dependent cell migration and invasion were both inhibited by treatment with celastrol. Finally, the antimetastatic activity of celastrol was examined in vivo using the B16F10-green fluorescent protein-injected C57BL/6 mouse model, as indicated by decreased pulmonary metastases in celastrol-administrated mice. Taken together, these data demonstrate for the first time that celastrol exerts potent antimetastatic activity both in vitro and in vivo, and they provide new evidence for the critical roles of p38 MAPK in the regulation of integrin function and cell adhesion.

Heterogeneous transition metal-based fluorescence polarization (HTFP) assay for probing protein interactions

Analyses of protein interactions are fundamental for the investigation of molecular mechanisms responsible for cellular processes and diseases, as well as for drug discovery in the pharmaceutical industry. The present study details the development of a fluorescence polarization assay using melanoma inhibitory activity (MIA) protein-binding compounds and studies of the binding properties of this protein. Since they are dependent on the the lifetime of the fluorescent label, currently available fluorescence polarization assays can only determine interactions with either high- or low-molecular weight interaction partners. Our new approach eliminates this limitation by immobilizing a known binding partner of MIA protein to a well plate and by labeling the target protein using luminescent transition metal labels such as Ru(bpy)3 for binding studies with both high- and low-molecular weight interaction partners. Due to the use of a functionalized surface, we termed our concept heterogeneous transition metal-based fluorescence polarization (HTFP) assay. The assay's independence from the molecular weight of potential binding partners should make the technique amenable to investigations on subjects as diverse as multimerization, interactions with pharmacophores, or binding affinity determination.

Hepatic gene expression profiling reveals protective responses in Atlantic salmon vaccinated against furunculosis

Background

Furunculosis, a disease caused with gram negative bacteria Aeromonas salmonicida produces heavy losses in aquaculture. Vaccination against furunculosis reduces mortality of Atlantic salmon but fails to eradicate infection. Factors that determine high individual variation of vaccination efficiency remain unknown. We used gene expression analyses to search for the correlates of vaccine protection against furunculosis in Atlantic salmon.

Results

Naïve and vaccinated fish were challenged by co-habitance. Fish with symptoms of furunculosis at the onset of mass mortality (LR - low resistance) and survivors (HR - high resistance) were sampled. Hepatic gene expression was analyzed with microarray (SFA2.0 - immunochip) and real-time qPCR. Comparison of LR and HR indicated changes associated with the protection and results obtained with naïve fish were used to find and filter the vaccine-independent responses. Genes involved in recruitment and migration of immune cells changed expression in both directions with greater magnitude in LR. Induction of the regulators of immune responses was either equal (NFkB) or greater (Jun) in LR. Expression levels of proteasome components and extracellular proteases were higher in LR while protease inhibitors were up-regulated in HR. Differences in chaperones and protein adaptors, scavengers of reactive oxygen species and genes for proteins of iron metabolism suggested cellular and oxidative stress in LR. Reduced levels of free iron and heme can be predicted in LR by gene expression profiles with no protection against pathogen. The level of complement regulation was greater in HR, which showed up-regulation of the components of membrane attack complex and the complement proteins that protect the host against the auto-immune damages. HR fish was also characterized with up-regulation of genes for proteins involved in the protection of extracellular matrix, lipid metabolism and clearance of endogenous and exogenous toxic compounds. A number of genes with marked expression difference between HR and LR can be considered as positive and negative correlates of vaccine protection against furunculosis.

Conclusion

Efficiency of vaccination against furunculosis depends largely on the ability of host to neutralize the negative impacts of immune responses combined with efficient clearance and prevention of tissue damages.

Processing of MIA protein during melanoma cell migration

MIA (melanoma inhibitory activity) protein, identified as a small 11 kDa protein highly expressed and secreted by malignant melanoma cells, plays an important functional role in melanoma development, progression and tumor cell invasion. Recent data describe a direct interaction of MIA protein with cell adhesion receptors integrin alpha(4)beta(1) and integrin alpha(5)beta(1) and extracellular matrix molecules. By modulating integrin activity MIA protein mediates detachment of melanoma cells from surrounding structures resulting in enhanced invasive and migratory potential. However, until today a detailed understanding of the processes of MIA function is missing. In this study, we show that after binding of MIA protein to integrin alpha(5)beta(1), MIA protein is internalized together with this cell adhesion receptor at the cell rear. This mechanism enables tumor cells to migrate in a defined direction as appropriate for invasion processes. Treatment of melanoma cells with PKC-inhibitors strongly reduced internalization of MIA protein. Endocytosis is followed by dissociation of MIA-integrin complexes. In acidic vesicles MIA protein is degraded while integrins are recycled. Treatment of melanoma cells with MIA inhibitory peptides almost completely blocked the MIA protein uptake into cells. As MIA protein has a major contribution to the aggressive characteristics of malignant melanoma in particular to formation of metastasis, it is important to elucidate the MIA functional mechanism in tumor cells to find novel therapeutic strategies in the fight against skin cancer.

Cadherin-7 interacts with melanoma inhibitory activity protein and negatively modulates melanoma cell migration

Melanoma inhibitory activity (MIA) has been identified as a small protein secreted from malignant melanoma cells, which strongly enhances melanoma cell migration and invasion. Detailed analyses performed by our group showed interaction of MIA with extracellular matrix proteins and integrin alpha4beta1 and alpha5beta1 leading to cellular detachment. In this study, we identified cadherin-7 as a new MIA-binding protein using surface-enhanced laser desorption/ionization-mass spectrometry technology and co-immunoprecipitation. Cadherin-7 is a classical cell-cell adhesion molecule which was shown to be upregulated in malignant melanoma. We demonstrated enhanced expression of cadherin-7 in primary tumor cells compared to metastatic cells. Upregulation of cadherin-7 expression in metastatic cell lines but also downregulation of expression in cells derived from primary melanomas resulted in reduced cell migration. In addition, we speculate that MIA/cadherin-7 interaction may regulate cell-cell adhesion of malignant melanoma cells influencing the migration of the cells. Interestingly, overexpression of cadherin-7 resulted in a decreased MIA mRNA expression. In addition, MIA effects on cell migration were abrogated in cell clones overexpressing cadherin-7. In conclusion, these findings suggest that cadherin-7 regulates the expression and activity of MIA and the migration of melanoma cells playing a role in tumor development of malignant melanoma.

High mobility group box-1-inducible melanoma inhibitory activity is associated with nodal metastasis and lymphangiogenesis in oral squamous cell carcinoma

Melanoma inhibitory activity (MIA) is an 11-kDa secretory protein isolated from malignant melanoma cells that is correlated with invasion and metastasis in various human malignancies. We examined MIA expression in 62 oral squamous cell carcinomas (OSCC) by immunohistochemistry. MIA expression was significantly associated with nodal metastasis (P = 0.00018). MIA expression was also associated with expression of high mobility group box-1 (HMGB1) (P < 0.0001) and lymph vessel density (P < 0.0001). Expression levels of MIA, HMGB1, nuclear factor kB (NFkB) p65 and HMGB1-NFkB p65 binding were significantly higher in a metastatic human OSCC cell line (HSC3) than those in a non-metastatic OSCC cell line (HSC4). Treatment with receptor for advanced glycation end products (RAGE) antisense or small interfering RNA and human recombinant HMGB1 (hrHMGB1) did not affect MIA expression, whereas HMGB1 antisense or siRNA treatment decreased MIA expression in HSC3 cells. Then HMGB1 enhanced MIA expression as an NFkB cofactor but not as a RAGE ligand. MIA neutralization by MIA antibodies increased extracellular signal-related kinase 1/2 phosphorylation, but decreased p38 phosphorylation and the expression of vascular epithelial growth factor (VEGF)-C and -D. Treatment with p38 inihibitor decreased VEGF-C and -D expression in HSC3 cells. These results suggest that MIA expression is enhanced by the interaction of intracellular HMGB1 and NFkBp65 and MIA is closely involved in tumor progression and nodal metastasis by the increments of VEGF-C and VEGF-D in OSCC.

Misexpression of MIA disrupts lung morphogenesis and causes neonatal death

Microarray experiments designed to identify genes differentially expressed in the E11.5 lung and trachea showed that melanoma inhibitory activity (Mia1) was expressed only in the lung. Mia1 was abundantly expressed during early lung development, but was virtually absent by the end of gestation. Distal embryonic lung epithelium showed high levels of Mia1 expression, which was suppressed by treatment with either retinoic acid or the FGF signaling antagonist SU5402. Late-gestation fetuses in which lung epithelial hyperplasia was induced by misexpression of FGF7 or FGF10 showed continued expression of Mia1 in areas of aberrant morphogenesis. Mia1 expression was also significantly increased in urethane-induced lung adenomas. Treatment of E18.5 lung explants with exogenous MIA caused significant reductions in the expression of the lung differentiation markers Sftpa, Sftpb, Sftpc, and Abca3. Bitransgenic mice expressing MIA under the control of the SFTPC promoter after E16.5, the age when Mia1 is normally silenced, died from respiratory failure at birth with morphologically immature lungs associated with reduced levels of saturated phosphatidylcholine and mature SP-B. Microarray analysis showed significant reductions in the expression of Sftpa, Sftpb, Abca3, Aqp5, Lzp-s, Scd2, and Aytl2 in lungs misexpressing MIA. These results suggest that the silencing of Mia1 that occurs in late gestation may be required for maturation of the surfactant system.

Antagonism of p66shc by melanoma inhibitory activity

The p66shc protein governs oxidant stress and mammalian lifespan. Here, we identify melanoma inhibitory activity (MIA), a protein secreted by melanoma cells, as a novel binding partner and antagonist of p66shc. The N-terminal collagen homology-2 (CH2) domain of p66shc binds to the Src Homology-3 (SH3)-like domain of MIA in vitro. In cells, ectopically expressed MIA and p66shc colocalize and co-precipitate. MIA also co-precipitates with the CH2 domain of p66shc in vivo. MIA expression in vivo suppresses p66shc-stimulated increase in endogenous hydrogen peroxide (H(2)O(2)), and inhibits basal and H(2)O(2)-induced phosphorylation of p66shc on serine 36 and H(2)O(2)-induced death. In human melanoma cells expressing MIA, endogenous MIA and p66shc co-precipitate. Downregulation of MIA in melanoma cells increases basal and ultraviolet radiation (UVR)-induced phosphorylation of p66shc on serine 36, augments endogenous H(2)O(2) levels, and increases their susceptibility to UVR-induced death. These findings show that MIA binds to p66shc, and suggest that this interaction antagonizes phosphorylation and function of p66shc.

Mechanism of UV-related carcinogenesis and its contribution to nevi/melanoma

Melanoma consists 4-5 % of all skin cancers, but it contributes to 71-80 % of skin cancers deaths. UV light affects cell and tissue homeostasis due to its damaging effects on DNA integrity and modification of expression of a plethora of genes. DNA repair systems protect cells from UV-induced lesions. Several animal models of melanoma have been developed (Xiphophorus, Opossum Monodelphis domestica, mouse models and human skin engrafts into other animals). This review discusses possible links between UV and genes significantly related to melanoma but does not discuss melanoma genetics. These include oncogenes, tumor suppressor genes, genes related to melanocyte-keratinocyte and melanocyte-matrix interaction, growth factors and their receptors, CRH, ACTH, α-MSH, glucocorticoids, ID1, NF-kappaB and vitamin D3.

TANGO is a tumor suppressor of malignant melanoma

The TANGO gene was originally identified as a new family member of the melanoma inhibitory activity gene family. The gene codes for a 14 kDa protein of so far unknown function. In our study we revealed that TANGO was downregulated or lost in 9 melanoma cell lines when compared to normal melanocytes and in most of the 8 tumor samples analyzed. The losses were associated with advanced stage of the disease. These results were confirmed in situ by immunohistochemistry on 10 paraffin-embedded sections of human malignant melanoma primary tumors and melanoma skin metastases. A small reduction of TANGO was also seen in different benign and atypical nevi when compared to normal skin. For functional analysis of TANGO we evaluated TANGO re-expressing melanoma cell clones and antisense TANGO cell clones with a complete loss of TANGO. Functional assays with TANGO transfected or treated cell lines revealed that TANGO expression reduces motility, whereas reduction of TANGO enhances migration. Our studies, therefore, indicate that reduction of TANGO expression contributes to tumor progression. These results taken together provide the first indications for a tumor suppressor role of TANGO gene in human malignant melanoma.