Role of cadherins and matrixins in melanoma

Combination blockade of KLRG1 and PD-1 promotes immune control of local and disseminated cancers

Checkpoint blockade therapy is effective against many cancers; however, new targets need to be identified to treat patients who do not respond to current treatment or demonstrate immune escape. Here, we showed that blocking the inhibitory receptor Killer cell lectin-like receptor G1 (KLRG1) enhances anti-tumor immunity mediated by NK cells and CD8⁺ T cells. We found that loss of KLRG1 signaling alone significantly decreased melanoma and breast cancer tumor growth in the lungs of mice. In addition, we demonstrated that KLRG1 blockade can synergize with PD-1 checkpoint therapy to increase the therapeutic efficacy compared to either treatment alone. This effect was even observed with tumors that do not respond to PD-1 checkpoint therapy. Double blockade therapy led to significantly decreased tumor size, increased frequency and activation of CD8⁺ T cells, and increased NK cell frequency and maturation in the tumor microenvironment. These findings demonstrate that KLRG1 is a novel checkpoint inhibitor target that affects NK and T cell anti-tumor immunity, both alone and in conjunction with established immunotherapies.

Role of Cadherins in Cancer-A Review

Cadherins play an important role in tissue homeostasis, as they are responsible for cell-cell adhesion during embryogenesis, tissue morphogenesis, differentiation and carcinogenesis. Cadherins are inseparably connected with catenins, forming cadherin-catenin complexes, which are crucial for cell-to-cell adherence. Any dysfunction or destabilization of cadherin-catenin complex may result in tumor progression. Epithelial mesenchymal transition (EMT) is a mechanism in which epithelial cadherin (E-cadherin) expression is lost during tumor progression. However, during tumorigenesis, many processes take place, and downregulation of E-cadherin, nuclear β-catenin and p120 catenin (p120) signaling are among the most critical. Additional signaling pathways, such as Receptor tyrosine kinase (RTK), Rho GTPases, phosphoinositide 3-kinase (PI3K) and Hippo affect cadherin cell-cell adhesion and also contribute to tumor progression and metastasis. Many signaling pathways may be activated during tumorigenesis; thus, cadherin-targeting drugs seem to limit the progression of malignant tumor. This review discusses the role of cadherins in selected signaling mechanisms involved in tumor growth. The clinical importance of cadherin will be discussed in cases of human and animal cancers.

Assessment of MMP29 Gene Expression and Silver Nanoparticles Effects on Colon Cancer Cell Line (HT29)

BACKGROUND

Colon cancer is a major cause of death around the world. The evaluation of novel approaches on corresponding genes would be a vital strategy toward eradication of cancer cells. In this study, the toxicity of silver nanoparticle on the colon cancer cell line (HT29) and expression of matrix metalloproteinase (MMP29) gene was investigated.

MATERIALS AND METHODS

The silver nanoparticle (AgNPs) was synthesized and assessed by transmission electron microscopy (TEM). The cytotoxicity of synthesized AgNP on the HT29 cell line was evaluated using the MTT assay. Furthermore, the expression of MMP29 gene was investigated by the quantitative real-time PCR (RT-qPCR).

RESULTS

The TEM results revealed that the fabricated AgNPs were mostly spherical in shape and had an average diameter of 22 nm. The results outlined that AgNPs significantly decreased the viability of cells in a dose- and time-dependent manner (p < 0.001). Additionally, we observed a significant difference among various concentrations.

CONCLUSION

The findings indicated that the green fabricated AgNPs have the potential as a promising approach toward the colon cancer therapy. Furthered studies are essential to evaluate against other cancer cell lines and genes participating in the cancer progress.

Snail-1 Silencing by siRNA Inhibits Migration of TE-8 Esophageal Cancer Cells Through Downregulation of Metastasis-Related Genes

Purpose: Snail-1 is a transcription factor, which takes part in EMT, a process related to the emergence of invasion and cancer progression. The purpose of this study was to evaluate the effect of Snail-1 silencing on the human esophageal squamous cell carcinoma cell line, namely TE-8, in vitro.

Methods: In this study, transfection of Snail-1 specific siRNA was conducted into TE-8 cells. The relative mRNA expression levels of Snail-1, Vimentin, CXCR4 and MMP-9 and transcription levels of miR-34a and let-7a were investigated by quantitative Real-time PCR. Western blotting was carried out to evaluate the Snail-1 protein level. Migration assay of TE-8 cells was also performed following the presence or absence of Snail-1 specific siRNA. MTT and TUNEL assays were performed to evaluate cell viability after Snail-1 silencing.

Results: It was found that treatment of cancer cells with the Snail-specific siRNA effectively downregulated the expression of Snail-1 in both mRNA and protein levels, and vimentin, CXCR4, and MMP-9 in mRNA level. However, it elevated the transcript levels of miR-34a and let-7a expressions. Furthermore, transfection of cancer cells with the Snail-specific siRNA significantly induced apoptosis in TE8 cells. Moreover, suppression of Snail-1 led to diminished cell migration.

Conclusion: It seems that Snail-specific siRNA can significantly interrupt esophageal cancer cell migration and reduce metastatic-related factors and induce miR-34a and let-7a in vitro. The bottom line is that therapeutic approaches via targeting Snail-1 can be used for ESCC treatment, suggesting that other possible target molecules for ESCC therapy require to be explored.

Transcriptional profiling of swine lung tissue after experimental infection with Actinobacillus pleuropneumoniae

Porcine pleuropneumonia is a highly contagious respiratory disease that causes great economic losses worldwide. In this study, we aimed to explore the underlying relationship between infection and injury by investigation of the whole porcine genome expression profiles of swine lung tissues post-inoculated with experimentally Actinobacillus pleuropneumoniae. Expression profiling experiments of the control group and the treatment group were conducted using a commercially available Agilent Porcine Genechip including 43,603 probe sets. Microarray analysis was conducted on profiles of lung from challenged versus non-challenged swine. We found 11,929 transcripts, identified as differentially expressed at the p ≤0.01 level. There were 1188 genes annotated as swine genes in the GenBank Data Base. GO term analysis identified a total of 89 biological process categories, 82 cellular components and 182 molecular functions that were significantly affected, and at least 27 biological process categories that were related to the host immune response. Gene set enrichment analysis identified 13 pathways that were significantly associated with host response. Many proinflammatory-inflammatory cytokines were activated and involved in the regulation of the host defense response at the site of inflammation; while the cytokines involved in regulation of the host immune response were suppressed. All changes of genes and pathways of induced or repressed expression not only led to a decrease in antigenic peptides presented to T lymphocytes by APCs via the MHC and alleviated immune response injury induced by infection, but also stimulated stem cells to produce granulocytes (neutrophils, eosinophils, and basophils) and monocyte, and promote neutrophils and macrophages to phagocytose bacterial and foreign antigen at the site of inflammation. The defense function of swine infection with Actinobacillus pleuropneumoniae was improved, while its immune function was decreased.

Topobiology of human pigmentation: P-cadherin selectively stimulates hair follicle melanogenesis

P-cadherin serves as a major topobiological cue in mammalian epithelium. In human hair follicles (HFs), it is prominently expressed in the inner hair matrix that harbors the HF pigmentary unit. However, the role of P-cadherin in normal human pigmentation remains unknown. As patients with mutations in the gene that encodes P-cadherin show hypotrichosis and fair hair, we explored the hypothesis that P-cadherin may control HF pigmentation. When P-cadherin was silenced in melanogenically active organ-cultured human scalp HFs, this significantly reduced HF melanogenesis and tyrosinase activity as well as gene and/or protein expression of gp100, stem cell factor, c-Kit, and microphthalmia-associated transcription factor (MITF), both in situ and in isolated human HF melanocytes. Instead, epidermal pigmentation was unaffected by P-cadherin knockdown in organ-cultured human skin. In hair matrix keratinocytes, P-cadherin silencing reduced plasma membrane β-catenin, whereas glycogen synthase kinase 3 beta (GSK3β) and phospho-β-catenin expression were significantly upregulated. This suggests that P-cadherin-GSK3β/Wnt signaling is required for maintaining the expression of MITF to sustain intrafollicular melanogenesis. Thus, P-cadherin-mediated signaling is a melanocyte subtype-specific topobiological regulator of normal human pigmentation, possibly via GSK3β-mediated canonical Wnt signaling.

TGF-β/SMAD/GLI2 signaling axis in cancer progression and metastasis

The Hedgehog (HH) and TGF-β signaling pathways represent essential regulators of cell proliferation and differentiation during embryogenesis. Pathway deregulation is a characteristic of various cancers. Recently, evidence for a convergence of these pathways at the level of the GLI2 transcription factor in the context of tumor initiation and progression to metastasis has emerged. This short review summarizes recent knowledge about GLI2 function and mechanisms of action downstream of TGF-β in cancer.

TGF-beta-RI kinase inhibitor SD-208 reduces the development and progression of melanoma bone metastases

Melanoma often metastasizes to bone where it is exposed to high concentrations of TGF-β. Constitutive Smad signaling occurs in human melanoma. Because TGF-β promotes metastases to bone by several types of solid tumors including breast cancer, we hypothesized that pharmacologic blockade of the TGF-β signaling pathway may interfere with the capacity of melanoma cells to metastasize to bone. In this study, we tested the effect of a small molecule inhibitor of TGF-β receptor I kinase (TβRI), SD-208, on various parameters affecting the development and progression of melanoma, both in vitro and in a mouse model of human melanoma bone metastasis. In melanoma cell lines, SD-208 blocked TGF-β induction of Smad3 phosphorylation, Smad3/4-specific transcription, Matrigel invasion and expression of the TGF-β target genes PTHrP, IL-11, CTGF, and RUNX2. To assess effects of SD-208 on melanoma development and metastasis, nude mice were inoculated with 1205Lu melanoma cells into the left cardiac ventricle and drug was administered by oral gavage on prevention or treatment protocols. SD-208 (60 mg/kg/d), started 2 days before tumor inoculation prevented the development of osteolytic bone metastases compared with vehicle. In mice with established bone metastases, the size of osteolytic lesions was significantly reduced after 4 weeks treatment with SD-208 compared with vehicle-treated mice. Our results demonstrate that therapeutic targeting of TGF-β may prevent the development of melanoma bone metastases and decrease the progression of established osteolytic lesions.

GLI2-mediated melanoma invasion and metastasis

BACKGROUND

The transforming growth factor-beta (TGF-beta) pathway, which has both tumor suppressor and pro-oncogenic activities, is often constitutively active in melanoma and is a marker of poor prognosis. Recently, we identified GLI2, a mediator of the hedgehog pathway, as a transcriptional target of TGF-beta signaling.

METHODS

We used real-time reverse transcription-polymerase chain reaction (RT-PCR) and western blotting to determine GLI2 expression in human melanoma cell lines and subsequently classified them as GLI2high or as GLI2low according to their relative GLI2 mRNA and protein expression levels. GLI2 expression was reduced in a GLI2high cell line with lentiviral expression of short hairpin RNA targeting GLI2. We assessed the role of GLI2 in melanoma cell invasiveness in Matrigel assays. We measured secretion of matrix metalloproteinase (MMP)-2 and MMP-9 by gelatin zymography and expression of E-cadherin by western blotting and RT-PCR. The role of GLI2 in development of bone metastases was determined following intracardiac injection of melanoma cells in immunocompromised mice (n = 5-13). Human melanoma samples (n = 79) at various stages of disease progression were analyzed for GLI2 and E-cadherin expression by immunohistochemistry, in situ hybridization, or RT-PCR. All statistical tests were two-sided.

RESULTS

Among melanoma cell lines, increased GLI2 expression was associated with loss of E-cadherin expression and with increased capacity to invade Matrigel and to form bone metastases in mice (mean osteolytic tumor area: GLI2high vs GLI2low, 2.81 vs 0.93 mm(2), difference = 1.88 mm(2), 95% confidence interval [CI] = 1.16 to 2.60, P < .001). Reduction of GLI2 expression in melanoma cells that had expressed high levels of GLI2 substantially inhibited both basal and TGF-beta-induced cell migration, invasion (mean number of Matrigel invading cells: shGLI2 vs shCtrl (control), 52.6 vs 100, difference = 47.4, 95% CI = 37.0 to 57.8, P = .024; for shGLI2 + TGF-beta vs shCtrl + TGF-beta, 31.0 vs 161.9, difference = -130.9, 95% CI = -96.2 to -165.5, P = .002), and MMP secretion in vitro and the development of experimental bone metastases in mice. Within human melanoma lesions, GLI2 expression was heterogeneous, associated with tumor regions in which E-cadherin was lost and increased in the most aggressive tumors.

CONCLUSION

GLI2 was directly involved in driving melanoma invasion and metastasis in this preclinical study.

GLI2-mediated melanoma invasion and metastasis

BACKGROUND

The transforming growth factor-beta (TGF-beta) pathway, which has both tumor suppressor and pro-oncogenic activities, is often constitutively active in melanoma and is a marker of poor prognosis. Recently, we identified GLI2, a mediator of the hedgehog pathway, as a transcriptional target of TGF-beta signaling.

METHODS

We used real-time reverse transcription-polymerase chain reaction (RT-PCR) and western blotting to determine GLI2 expression in human melanoma cell lines and subsequently classified them as GLI2high or as GLI2low according to their relative GLI2 mRNA and protein expression levels. GLI2 expression was reduced in a GLI2high cell line with lentiviral expression of short hairpin RNA targeting GLI2. We assessed the role of GLI2 in melanoma cell invasiveness in Matrigel assays. We measured secretion of matrix metalloproteinase (MMP)-2 and MMP-9 by gelatin zymography and expression of E-cadherin by western blotting and RT-PCR. The role of GLI2 in development of bone metastases was determined following intracardiac injection of melanoma cells in immunocompromised mice (n = 5-13). Human melanoma samples (n = 79) at various stages of disease progression were analyzed for GLI2 and E-cadherin expression by immunohistochemistry, in situ hybridization, or RT-PCR. All statistical tests were two-sided.

RESULTS

Among melanoma cell lines, increased GLI2 expression was associated with loss of E-cadherin expression and with increased capacity to invade Matrigel and to form bone metastases in mice (mean osteolytic tumor area: GLI2high vs GLI2low, 2.81 vs 0.93 mm(2), difference = 1.88 mm(2), 95% confidence interval [CI] = 1.16 to 2.60, P < .001). Reduction of GLI2 expression in melanoma cells that had expressed high levels of GLI2 substantially inhibited both basal and TGF-beta-induced cell migration, invasion (mean number of Matrigel invading cells: shGLI2 vs shCtrl (control), 52.6 vs 100, difference = 47.4, 95% CI = 37.0 to 57.8, P = .024; for shGLI2 + TGF-beta vs shCtrl + TGF-beta, 31.0 vs 161.9, difference = -130.9, 95% CI = -96.2 to -165.5, P = .002), and MMP secretion in vitro and the development of experimental bone metastases in mice. Within human melanoma lesions, GLI2 expression was heterogeneous, associated with tumor regions in which E-cadherin was lost and increased in the most aggressive tumors.

CONCLUSION

GLI2 was directly involved in driving melanoma invasion and metastasis in this preclinical study.

MMP19 is upregulated during melanoma progression and increases invasion of melanoma cells

During the progression of cutaneous melanomas, matrix metalloproteinases (MMPs) facilitate the tumour cells to traverse the basement membrane and invade the dermis. In this study, we analysed the expression of MMP19 in the course of melanoma progression. Although MMP19 was absent in melanocytes and melanoma cells of early stages of melanoma development, its expression was strongly upregulated in the neighbouring keratinocytes that may facilitate the vertical outgrowth of melanoma cells. In contrast to early stages, MMP19 was upregulated during the vertical growth phase of melanoma and in metastases. The upregulation of MMP19 in melanoma of Clark levels IV and V correlates with that of MMP2 and also simultaneously with ceased expression of E-cadherin. To reveal whether MMP19 facilitates the invasion of melanomas, we examined adhesion and migratory capacity of selected melanoma cell lines. Melanoma cell lines with low expression of MMP19 exhibited increased adhesion to various substrates and lower migration in comparison with the cell line with higher expression of MMP19. Moreover, ectopic expression of MMP19 could restore the migratory capacity of melanoma cells with low endogenous level of MMP19. These results suggest that the increase of MMP19 expression hallmarks the progression of cutaneous melanoma and might augment melanoma growth by promoting the invasion of tumour cells.

Cellular cohesion as a prognostic factor in malignant melanoma: a retrospective study with up to 12 years follow-up

Malignant melanomas have a high metastatic potential. Although the depth of tumour invasion is the single most important histological prognostic factor, in clinical practice this correlation is frequently challenged. In this study, we assessed the cohesion of malignant melanocytes in the dermal component of all primary melanomas in vertical growth phase with tumour thickness >0.76 mm diagnosed in our Department between 1990 and 1995. The rationale behind this morphological evaluation was based on the hypothesis that a change in the adhesion molecule profile of melanoma cells may manifest visually discrete changes in the way that cells group together in dermal aggregates. We used a dyscohesion score based on the proportion of invasive tumour occupied by dyscohesive neoplastic cells and assessed its clinical significance by correlating it with the incidence of recurrence, regional and distant metastases and survival of the patients. Follow-up was up to 12 years. We found that the degree of melanoma cell dyscohesion was associated with the probability of local recurrence or metastasis. This correlation was particularly significant when dyscohesion involving an area smaller than 25% (dyscohesion score 1) of the dermal component was compared to dyscohesion involving a larger area (scores 2-4). Melanomas in the latter group had significantly increased likelihood of recurrence or metastasis (P<0.025, log-rank test). This was particularly the case in T1-T3 melanomas (P<0.005). Similarly, T1-T3 melanomas with dyscohesion score 1 had a significantly higher survival rate (P<0.025). In the same cohort, both disease-free survival and survival were not significantly correlated to thickness, probably due to the limited number of cases. Finally, we showed that extent of dyscohesion was independent of Breslow thickness or tumour regression. We believe that estimation of melanoma cell dyscohesion is a reliable histological prognostic factor that may be appropriate in clinical practice.

Melanoma proteoglycan modifies gene expression to stimulate tumor cell motility, growth, and epithelial-to-mesenchymal transition

Melanoma chondroitin sulfate proteoglycan (MCSP) is a plasma membrane-associated proteoglycan that facilitates the growth, motility, and invasion of tumor cells. MCSP expression in melanoma cells enhances integrin function and constitutive activation of Erk1,2. The current studies were performed to determine the mechanism by which MCSP expression promotes tumor growth and motility. The results show that MCSP expression in radial growth phase, vertical growth phase, or metastatic cell lines causes sustained activation of Erk1,2, enhanced growth, and motility which all require the cytoplasmic domain of the MCSP core protein. MCSP expression in a radial growth phase cell line also promotes an epithelial-to-mesenchymal transition based on changes in cell morphology and the expression of several epithelial-to-mesenchymal transition markers. Finally, MCSP enhances the expression of c-Met and hepatocyte growth factor, and inhibiting c-Met expression or activation limits the increased growth and motility of multiple melanoma cell lines. The studies collectively show the importance of MCSP in promoting progression by an epigenetic mechanism and they indicate that MCSP could be targeted to delay or inhibit tumor progression in patients.

The biochemical and functional food properties of the bowman-birk inhibitor

The Bowman-Birk inhibitor (BBI) is a small water-soluble protein present in soybean and almost all monocotyledonous and dicotyledonous seeds. The molecular size of BBI ranges from 1,513 Da to about 20,000 Da. BBI is to seeds what alpha(1)-antitrypsin is to humans. Soy-based food products rich in BBI include soybean grits, soymilk, oilcake, soybean isolate, and soybean protein concentrate. BBI is stable within the pH range encountered in most foods, can withstand boiling water temperature for 10 min, resistant to the pH range and proteolytic enzymes of the gastrointestinal tract, bioavailable, and not allergenic. BBI reduces the proteolytic activities of trypsin, chymotrypsin, elastase, cathepsin G, and chymase, serine protease-dependent matrix metalloproteinases, urokinase protein activator, mitogen activated protein kinase, and PI3 kinase, and upregulates connexin 43 (Cx43) expression. Several studies have demonstrated the efficacy of BBI against tumor cells in vitro, animal models, and human phase IIa clinical trials. FDA considers BBI as a drug. In 1999, FDA allowed a health claim on food labels stating that a daily diet containing 25 grams of soy protein, also low in saturated fat and cholesterol, may reduce the risk of heart disease [corrected] This review highlights the biochemical and functional food properties of the Bowman-Birk inhibitor.

The melanocyte and the epidermal melanin unit: an expanded concept

There are many mechanisms by which melanocytes, keratinocytes, and Langerhans cells interact within the epidermis. Inflammatory mediators affect melanocyte function and melanogenic agents such as alpha-MSH alter the functions of keratinocytes and Langerhans cells. The epidermal melanin unit is better labeled the KLM unit.

Gene expression signatures for tumor progression, tumor subtype, and tumor thickness in laser-microdissected melanoma tissues

PURPOSE

To better understand the molecular mechanisms of malignant melanoma progression and metastasis, gene expression profiling was done of primary melanomas and melanoma metastases.

EXPERIMENTAL DESIGN

Tumor cell-specific gene expression in 19 primary melanomas and 22 melanoma metastases was analyzed using oligonucleotide microarrays after laser-capture microdissection of melanoma cells. Statistical analysis was done by random permutation analysis and support vector machines. Microarray data were further validated by immunohistochemistry and immunoblotting.

RESULTS

Overall, 308 genes were identified that showed significant differential expression between primary melanomas and melanoma metastases (false discovery rate<or=0.05). Significantly overrepresented gene ontology categories in the list of 308 genes were cell cycle regulation, mitosis, cell communication, and cell adhesion. Overall, 47 genes showed up-regulation in metastases. These included Cdc6, Cdk1, septin 6, mitosin, kinesin family member 2C, osteopontin, and fibronectin. Down-regulated genes included E-cadherin, fibroblast growth factor binding protein, and desmocollin 1 and desmocollin 3, stratifin/14-3-3sigma, and the chemokine CCL27. Using support vector machine analysis of gene expression data, a performance of >85% correct classifications for primary melanomas and metastases was reached. Further analysis showed that subtypes of primary melanomas displayed characteristic gene expression patterns, as do thin tumors (<or=1.0 mm Breslow thickness) compared with intermediate and thick tumors (>2.0 mm Breslow thickness).

CONCLUSIONS

Taken together, this large-scale gene expression study of malignant melanoma identified molecular signatures related to metastasis, melanoma subtypes, and tumor thickness. These findings not only provide deeper insights into the pathogenesis of melanoma progression but may also guide future research on innovative treatments.

[The role of matrix metalloproteinases and tissue inhibitors of metalloproteinases in invasion of tumours of neuroepithelial tissue]

Tumour invasion requires degradation of extracellular matrix components and migration of cells through degraded structures into surrounding tissues. Matrix metalloproteinases (MMP) constitute a family of zinc and calcium-dependent endopeptidases that play a key role in the breakdown of extracellular matrix, and in processing of cytokines, growth factors, chemokines and cell surface receptors. Their activity is regulated at the levels of transcription, activation and inhibition by tissue inhibitors of metalloproteinases (TIMP). Changes in expression of MMP and TIMP are implicated in tumour invasion, because they may contribute to both migration of tumour cells and angiogenesis. Alterations of MMP expression observed in brain tumours arouse interest in the development and evaluation of synthetic matrix metalloproteinase inhibitors as antitumour agents.

E-cadherin and its downstream catenins are proteolytically cleaved in human HaCaT keratinocytes exposed to UVB

It has been reported that ultraviolet B (UVB) irradiation causes the loss of E-cadherin of melanocytes, leading them to escape from neighboring keratinocytes during melanoma development. However, little has been paid on its effect on E-cadherin of keratinocytes. In the present study we therefore focus on whether UVB affects expression of E-cadherin-catenin complex in human HaCaT keratinocytes. We found that E-cadherin, beta-, and gamma-catenin but not alpha-catenin were proteolytically cleaved in UVB-irradiated HaCaT keratinocytes. The effect was only observed in keratinocyte undergoing apoptosis. Cleavage of beta- and gamma-catenin was fully abolished by caspase-3 and caspase-8 inhibitors, whereas cleavage of E-cadherin was inhibited by neither caspase nor metalloproteinase inhibitors. Functional analysis showed that the cleavage resulted in the disruption of the physical association between E-cadherin and catenins, indicating that E-cadherin signaling was compromised in UVB-irradiated HaCaT keratinocytes. Because E-cadherin in keratinocytes plays important roles in mediating cell-cell adhesion in epidermis of skin, the loss of E-cadherin and signaling components in keratinocytes may lead to the disruption of skin integrity after UVB exposure.

DNA microarray technology and its applications in dermatology

The use of DNA microarray technology in biomedical research has dramatically increased during the past years. In the present report, we provide an overview on the basic DNA microarray technology and biostatistical methods for gene expression analysis. A focus is then put on its applications in dermatological research. In recent years, a series of gene expression studies have been performed for various dermatological diseases, such as malignant melanoma, psoriasis and lupus erythematosus. These analyses have identified interesting target genes as well as putative disease susceptibility loci. However, further functional studies will be needed for a more complete understanding of the pathogenesis of these diseases. This may be performed by means of the recently developed RNA interference technology. Besides its role in large-scale gene expression studies, DNA microarray technology has proved to be a valuable tool for genomic screens of genetic alterations, e.g. single nucleotide polymorphisms. These play a role in tumour development and progression, and also function as genetic markers for disease susceptibility. Taken together, DNA microarray technology opens enormous perspectives for dermatologists. It may help us understand the complex pathogenesis of a wide variety of dermatologic diseases and identify their genetic background.

Axis of evil: molecular mechanisms of cancer metastasis

Although the genetic basis of tumorigenesis may vary greatly between different cancer types, the cellular and molecular steps required for metastasis are similar for all cancer cells. Not surprisingly, the molecular mechanisms that propel invasive growth and metastasis are also found in embryonic development, and to a less perpetual extent, in adult tissue repair processes. It is increasingly apparent that the stromal microenvironment, in which neoplastic cells develop, profoundly influences many steps of cancer progression, including the ability of tumor cells to metastasize. In carcinomas, the influences of the microenvironment are mediated, in large part, by bidirectional interactions (adhesion, survival, proteolysis, migration, immune escape mechanisms lymph-/angiogenesis, and homing on target organs) between epithelial tumor cells and neighboring stromal cells, such as fibroblasts as well as endothelial and immune cells. In this review, we summarize recent advances in understanding the molecular mechanisms that govern this frequently lethal metastatic progression along an axis from primary tumor to regional lymph nodes to distant organ sites. Affected proteins include growth factor signaling molecules, chemokines, cell-cell adhesion molecules (cadherins, integrins) as well as extracellular proteases (matrix metalloproteinases). We then discuss promising new therapeutic approaches targeting the microenvironment. We note, however, that there is still too little knowledge of how the many events are coordinated and integrated by the cancer cell, with conspiratorial help by the stromal component of the host. Before drug development can proceed with a legitimate chance of success, significant gaps in basic knowledge need to be filled.

Plasma MMP-9 (92 kDa-MMP) activity is useful in the follow-up and in the assessment of prognosis in breast cancer patients

Previously we determined that plasma MMP-9 activity was significantly elevated in breast cancer patients compared to benign mammary pathologies and healthy controls. Now we analyzed its potential usefulness in the follow-up and in the prognosis of these patients. MMP-9 activity was measured by gelatin quantitative zymography in the euglobulin plasma fraction of 46 breast cancer patients in a 38-month follow-up study. Blood samples were obtained before surgery (S1), 1 month after (S2) and every 3 months. The relapse-free survival (RFS) and overall survival (OS) analysis was performed along 56 months in 113 patients using the Kaplan-Meier curves and Cox analysis. In 63% of the S2 analyzed, MMP-9 decreased after surgery. In 44 patients evaluated during the adjuvant period who developed a complete response, MMP-9 decreased compared to their S1, whereas 2 patients showed an enhancement in correlation with lack of response. Further analysis indicated that in all patients who never showed evidence of recurrence, plasma MMP-9 activity remained low, but it increased 1 to 8 months preceding the clinical detection of progression in those patients who relapsed. Kaplan-Meier curves indicated that high levels of plasma MMP-9 activity at the moment of breast cancer diagnosis were associated with a worse OS rate. Cox analysis showed it was not associated with tumor stage or patient's age. Our results, which show a good correlation between plasma MMP-9 activity and the clinical status of each patient, suggest its usefulness as a marker both in the follow-up and in the prognosis of breast cancer patients.

Laminin, hyaluronan, tenascin-C and type VI collagen levels in sera from patients with malignant melanoma

In this study, hyaluronan, laminin-1, tenascin-C and type VI collagen were measured in the sera of patients with stage I/II and stage IV melanoma. A significant increase in the serum levels of all four extracellular matrix proteins was found in patients with stage IV melanoma compared to healthy donors. Type VI collagen and hyaluronan serum levels were also significantly increased in stage I/II melanoma. Increased expression of the four matrix proteins was also demonstrated in melanoma cell lines using reverse transcriptase- polmerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). We suggest that tenascin-C, hyaluronan, laminin-1 and type VI collagen are involved in melanoma development and extracellular matrix remodelling during melanoma progression. This finding will be of interest in the development of serum markers for progression of malignant melanoma.

Animal models of melanoma: an HGF/SF transgenic mouse model may facilitate experimental access to UV initiating events

Cutaneous malignant melanoma, the most lethal of the skin cancers, known for its intractability to current therapies, continues to increase in incidence, providing a significant public health challenge. There is a consensus that skin cancer is initiated by sunlight exposure. For non-melanoma skin cancer there is substantial evidence that chronic exposure to the ultraviolet B radiation (UVB) (280-320 nm) portion of the sunlight spectrum is responsible. Experimentally, UVB is mutagenic and chronic UVB exposure can cause non-melanoma skin cancer in laboratory animals. Non-melanoma tumors in animals and in humans show characteristic UVB signature lesions in the tumor suppressor p53 and/or in the patched (PTCH) gene. An action spectrum or wavelength dependence for squamous cell carcinoma in the mouse shows a major peak of efficacy in the UVB. For malignant melanoma, however, the situation is unclear and the critical direct target(s) of sunlight in initiating melanoma and even the wavelengths responsible are as yet unidentified. This lack of information is in major part a result of a paucity of animal models for melanoma which recapitulate the role of sunlight in initiating this disease. The epidemiology of melanoma differs significantly from non-melanoma skin cancer. Intense sporadic sunlight exposure in childhood, probably exacerbated by additional adult exposure, is associated with elevated melanoma risk. Melanoma is also a disease of gene-environment interactions with underlying genetic factors playing a significant role. These major differences indicate that extrapolation from information for non-melanoma skin cancer to melanoma is unlikely to be useful. We summarize in this review the experimental information available on the role of UV radiation in melanoma and give an overview of animal melanoma models. A new model derived by neonatal UV irradiation of hepatocyte growth factor/scatter factor (HGF/SF) transgenic mice is described which recapitulates the etiology, the histopathology and molecular pathogenesis of human disease. It is anticipated that the HGF/SF transgenic model will provide a means to access the mechanism(s) by which sunlight initiates this lethal disease and provide an appropriate vehicle for derivation of appropriate therapeutic and preventive strategies.

Genetic basis of human breast cancer metastasis

Once cancer cells have spread and formed secondary masses, breast cancers are largely incurable even with state-of-the-art medicine. To improve diagnosis and therapy, better markers are needed to distinguish cells which have a high probability for causing clinically relevant, macroscopic metastases. In this review, we summarize the several genes that regulate breast cancer metastasis. Two categories of genes are presented--metastasis activator (ras, MEK1, mta1, proteinases, adhesion molecules, chemoattractants/receptors, autotaxin, PKC, S100A4, RhoC, osteopontin) and metastasis suppressor (Nm23, E-cadherin, TIMPs, KiSS1, Kai1, Maspin, MKK4, BRMS1). While the mechanisms of action for most of these genes are not fully elucidated, some clues are emerging and are presented.