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Early differential diagnosis between malignant and benign tumors and their underlying intrinsic differences are the most critical issues for life-threatening cancers. To study whether human acral melanomas, deadly cancers that occur on non-hair-bearing skin, have distinct origins that underlie their invasive capability, we develop fate-tracing technologies of melanocyte stem cells in sweat glands (glandular McSCs) and in melanoma models in mice and compare the cellular dynamics with human melanoma. Herein, we report that glandular McSCs self-renew to expand their migratory progeny in response to genotoxic stress and trauma to generate invasive melanomas in mice that mimic human acral melanomas. The analysis of melanocytic lesions in human volar skin reveals that genetically unstable McSCs expand in sweat glands and in the surrounding epidermis in melanomas but not in nevi. The detection of such cell spreading dynamics provides an innovative method for an early differential diagnosis of acral melanomas from nevi.

The classic model for development of a human therapeutic involves initial chemical/molecular selection or design, in vitro testing, and frequently molecular optimization. The Food and Drug Administration preclinical testing for safety for eventual human trials usually requests two animal species to be evaluated (one rodent and one non-rodent). A major reason cited for the inefficiency of drug development is the relatively low power of current rodent models to predict therapeutic efficacy in humans. A review of the scientific literature demonstrates numerous examples in which successful murine studies did not predict success in humans. A widely distributed and updated volume of fascicles of Animal Models of Human Disease was published by the Armed Forces Institute of Pathology in 1979. Naturally occurring melanoma in dogs has continued to be studied as a complementary model for human melanoma treatment. In 2016, researchers at the University of Colorado School of Medicine and Colorado State University College of Veterinary Medicine collaborated on a canine study using photodynamic therapy to treat lung cancer via bronchoscopy.

The synthesis and characterization of potent 7-substituted-2-(4-substitutedphenyl)imidazo[2,1-b][1,3]benzothiazoles as effective radiosensitizers and anticarcinogenic compound is reported. The activity is determined against human liver cancer Hep G2 cell line, two parental melanoma cell lines (human melanoma cell line, A375C and mouse melanoma cell line, A375C). The compounds 7-sulfonamide-2-(4-fluorophenyl)imidazo[2,1-b][1,3]benzothiazole (3f, IC50 = 0.097 μM) and 7-sulfonamide-2-(4-methylphenyl)imidazo[2,1-b][1,3]benzothiazole (3g, IC50 = 0.114 μM) exhibited considerable in vitro anticancer activity against Hep G2 cell line while 7-bromo-2-(4-fluorophenyl)imidazo[2,1-b][1,3]benzothiazole showed effectiveness against both parental melanoma cell lines (3c, IC50 = 0.04 and 0.052 μM). Further the active molecules 3f, 3g and 3h are tested for radiosensitizing activity over Hep G2 cell line at 4 Gy, with the comet formed at 0.054 μM . Similarly, 3c tested against two parental melanoma cell lines, it has proven to be more potent when combined with 2 Gy ϒ-radiation. The present study reveals that presence of sulfonamide in combination with methoxy substitution enhanced DNA fragmentation and there by acting as effective derivative for Hepatocellular carcinoma.

A 67-year-old female with a history of colon cancer underwent colonoscopy. An 8 mm semi-pedunculated, friable, and ulcerated lesion of the ascending colon was removed completely using a hot snare. Immunohistochemical staining showed strong positivity for transcription factor binding to IGHM enhancer 3 (TFE-3) and was partially positive for Human Melanoma Black (HMB-45), consistent with a diagnosis of perivascular epithelioid cell tumor (PEComa). The patient underwent endoscopic submucosal dissection of the residual lesion in the ascending colon without complications. Here, we discuss the clinical and histopathologic characterizations that helped guide the diagnosis and management of this exceedingly rare entity.

While much of the research concerning factors associated with responses to immunotherapies focuses on the contributions of conventional peptide-specific T cells, the role of unconventional T cells, such as mucosalassociated invariant T (MAIT) cells, in human melanoma remains largely unknown. MAIT cells are innate-like T cells expressing a semi-invariant T cell receptor restricted to the non-classical MHC class I molecule MR1 presenting vitamin metabolites derived from bacteria. In this prospective clinical study, we sought to characterize MAIT cells in melanoma patients and determine their association with clinical outcomes. We identified tumor-infiltrating MAIT cells in melanomas across metastatic sites and found that the number of circulating MAIT cells is reduced in melanoma patients. However, circulating MAIT cell frequency is restored by anti-PD1 treatment in responding patients, correlating with treatment responses in which patients with high frequencies of MAIT cells exhibited improved overall survival. These data provide evidence for leveraging MAIT cells and their functions as novel targets for future therapies.

The purpose of this study was to figure out the dysregulation of miR-942-5p in melanoma and its role in melanoma pathogenesis.Quantitative real-time PCR (qRT-PCR) assay was used to determine the change of RNA expression. Protein expression was examined by Western blotting. miRNA target was validated through TargetScan and luciferase assay. Cell migration and invasion were detected by wound healing and transwell assay, respectively.Results of qRT-PCR manifested miR-942-5p were upregulated in melanoma cell. High expression of miR-942-5p in melanoma patients presented a poor prognosis. Upregulation of miR-942-5p accelerated cell proliferation, migration, and invasion in melanoma cells. Cell apoptosis was inhibited by miR-942-5p mimics. Suppression of miR-942-5p by its inhibitor showed the opposite effects in melanoma cells. TargetScan and luciferase assay showed that miR-942-5p directly targeted to the 3'-untranslated region (3'-UTR) of DKK3. Overexpression of DKK3 inhibited GSK-3β phosphorylation and reduced the expression of β-catenin in both cytoplasm and nucleus, which were induced by miR-942-5p mimics leading to the activation of Wnt/β-catenin pathway.Upregulation of miR-942-5p was observed in melanoma cells and tissues and significantly associated with a poor prognosis. Though targeting 3'-UTR of DKK3, miR-942-5p could activate Wnt/β-catenin pathway, resulting in melanoma cell proliferation, migration, and invasion, which promoted the development of melanoma. These results showed that miR-942-5p might be a diagnosis and prognosis biomarker in melanoma.

The goal of this study is to explore the effects of columbamine in melanoma cells and the signaling pathway involved.Human melanoma cell line A375 cells were used in this study. Cell proliferative ability was detected by MTT assay and clone formation assay. Cell migration and invasion were measured by wound healing assay and transwell assay, respectively. Protein expression was examined by Western blotting.Columbamine reduced cell proliferative ability and the number of clone spots in A375 cells. Western blotting results demonstrated that expression of cleaved caspase 3, an activated cell death protease, was upregulated by 20 and 50 µM of columbamine. Wound healing results showed that the scratch width was wider in cell treated with 20 and 50 µM of columbamine than that in cell treated with 0 and 10 µM of columbamine. Phosphorylation of STAT3 and expression of HSP90 was also repressed by columbamine in a concentration-dependent manner. Overexpression of HSP90 attenuated the inhibition of cell proliferation, migration and invasion induced by columbamine.Columbamine inhibited melanoma cell proliferation, migration, and invasion in A375 cells through inactivation of STAT3, which is mediated by HSP90.

Fluorescent tools have revolutionized our capability to visualize, probe, study, and understand the biological cellular properties, processes and dynamics, enabling researchers to improve their knowledge for example in cancer field. In this paper, we use the peculiar properties of our Imiqualines derivatives to study their cellular penetration and distribution in a human melanoma cell line A375 using confocal microscopy. Preliminary results on colocalization with the potent protein target c-Kit of our lead are also described.

The identification of liquid biomarkers remains a major challenge to improve the diagnosis of melanoma patients with brain metastases. Circulating miRNAs packaged into tumor-secreted small extracellular vesicles (sEVs) contribute to tumor progression. To investigate the release of tumor-secreted miRNAs by brain metastasis, we developed a xenograft model where human metastatic melanoma cells were injected intracranially in nude mice. The comprehensive profiles of both free miRNAs and those packaged in sEVs secreted by the melanoma cells in the plasma demonstrated that most (80%) of the sEV-associated miRNAs were also present in serum EVs from a cohort of metastatic melanomas, included in a publicly available dataset. Remarkably, among them, we found three miRNAs (miR-224-5p, miR-130a-3p and miR-21-5p) in sEVs showing a trend of upregulation during melanoma progression. Our model is proven to be valuable for identifying miRNAs in EVs that are unequivocally secreted by melanoma cells in the brain and could be associated to disease progression.

Visualization and classification of cell cycle stages in live cells requires the introduction of transient or stably expressing fluorescent markers. This is not feasible for all cell types, and can be time consuming to implement. Labelling of living cells also has the potential to perturb normal cellular function. Here we describe a computational strategy to estimate core cell cycle stages without markers by taking advantage of features extracted from information-rich ptychographic time-lapse movies. We show that a deep-learning approach can estimate the cell cycle trajectories of individual human melanoma cells from short 3-frame (~23 minute) snapshots, and can identify cell cycle arrest induced by chemotherapeutic agents targeting melanoma driver mutations.

Phytochemical investigation of Physalis minima led to the isolation of six new withanolides, including physaminilides H K (1–4), two artificial withanolides (5–6), and 19 known ones (7–25). Their structures were elucidated on the basis of spectroscopic analysis, including NMR and electronic circular dichroism (ECD) data. The isolates were evaluated for their cytotoxic activities against A375 human melanoma cells. Compounds 1, 8–9, 12–13, 15–17 and 19 exhibited significant cytotoxic activities with IC50 values in the range of 1.2–7.5 μM.

The review presents a discussion on articles and patents, describing new in vitro and in vivo models of pigmented or non-pigmented human cutaneous melanoma, received in NMRCO from the patients» metastases. Molecular genetic characteristics of the new models is supported by the arguments in addition to the given data and visual materials. The subjects of the discussed publications are 3 polyclonal cell lines, 2 subclones and 4 subcutaneous (s/c) xenografts in immunodeficient mice Balb/c nude. All the models are stored in Cryo Collection with xenografts at N.N. Blokhin NMRCO as well as in the Russian Collection of Cell Cultures of Vertebrae (RCCCV, St. Petersburg). This mini-collection is recommended for use in basic research of cutaneous melanoma and pre-clinical studies of anti-melanoma agents. The basis for these studies are the appropriate characteristics of the models, including cytological, immunologic, transplantation and molecular-genetic ones, as well as in vivo drug sensitivity to the corresponding target therapy.

Previous clinical studies showed that menstruating females were better protected in melanoma than post-menopausal women and men of any age. In addition, epidemiological studies showed an increased male mortality in melanoma. But these studies did not correlate with steroid status in females. Our in-vitro study showed female sex hormone progesterone significantly inhibited human melanoma cell growth. Further in-vitro study showed that progesterone action was mediated by a specific suppression of pro-inflammatory cytokine IL-8. Our research also showed that addition of IL-8 (1 ng/ml) to melanoma cells stimulated cell growth (117%) and suppression of IL-8 by curcumin (100 μM) pre-treatment suppressed human melanoma cell growth (26%) in-vitro. This observation prompted us to check the effect of male sex hormones androstenedione (AD) and testosterone (T) on melanoma cell growth. AD and T also suppressed cell growth and IL-8 secretion, but not as significantly as that of progesterone. However, addition of progesterone (10 μM) along with androgens showed an additive effect on the inhibition of melanoma cell growth and suppression of IL-8 secretion. As steroids (P, AD, T) targeted IL-8 for their action, it was decided to check whether vitamin-D3 also targeted IL-8 secretion and cell growth. Active form of vit-D3 (25 μM) also suppressed IL-8 secretion and cell growth. But, addition of progesterone (50 μM) along with D3 significantly suppressed cell growth and IL-8 secretion. This brought IL-8 into focus as a key molecule regulating melanoma cell growth. In order to check whether IL-8 was the molecule involved in regulating melanoma cell growth, IL-8 rescue experiment after curcumin (25 μM) pre-treatment was carried out. IL-8 (100 ng/ml) was able to rescue cell growth completely after pre-treatment with curcumin, suggesting IL-8 was the molecule involved in regulating melanoma cell growth. Literature also suggested important role for IL-8 in regulating melanoma cell growth. Conditional expression of IL-8 in nude mouse by Dr. Singh et al., indicated in-vivo role of IL-8 in melanoma growth and metastasis. Conclusion: Both, in-vitro and in-vivo studies suggested an important role for IL-8 in regulating melanoma growth and metastasis. So, IL-8 could be targeted to arrest melanoma growth and metastasis in-vivo. Hence, IL-8 could be a potential target for melanoma treatment.

Aranosa, nitrozourea derivative is a DNA-methylating agent that has been approved for treatment of patients with disseminated melanoma. Aranoza effect is based on DNA damage and then as a result apoptosis mechanisms start launching. The important role in this process must be played by p53 protein, and its different dysfunctions can result in drug resistance. Objective. The purpose is to study p53 mutational status in cell lines of human skin metastatic melanoma and to estimate its connection with сell lines resistance to aranoza. Materials and methods. The research was conducted on 14 cell lines of human skin metastatic melanoma. Aranoza IC50 for cell lines was determined by MTT-test. The 17р chromosome’s condition was estimated by fluorescence in situ hybridization. The presence of point mutations in DNA-binding domain of human p53 was researched by Sanger sequencing. Results. Skin metastatic melanoma cell lines had different sensitivity to aranoza. Almost all cell lines were heterogeneous in the condition of 17 th chromosome. P53 point mutations were found in 2 cell lines. But one part of resistant cell lines almost didn’t have any mutational disorders of p53, another part of resistant lines on the contrary had plenty of p53 mutational disorders. Conclusion. The correlation of resistance and p53 mutations can be established for one part of human skin metastatic melanoma cell lines. But for another part of human skin metastatic melanoma cell lines resistance most likely are driven by other mechanisms.

Digital holographic cytometry (DHC) and other methods of quantitative phase imaging permit extended time-lapse imaging of mammalian cells in the absence of induced cellular toxicity. Manufactured DHC platforms equipped with semi-automated image acquisition, segmentation, and analysis software packages (or modules) for assessing cell behavior are now commercially available. When housed in mammalian cell incubators these cytometers offer the potential to monitor and quantify a range of cellular behaviors without disrupting routine culture. Realization of this potential requires validation against established standards. Two proprietary software modules for assessing cellular motility available using the HoloMonitor M4 DHC platform were evaluated on human melanoma cells lines with known relative motility and metastatic potential. One such software package, the Track Cells module, was run during routine culture. In addition, the Wound Healing module was conducted in parallel with established transwell migration and invasion assays. Each module was evaluated for reproducibility and correlation to established assays. Both software modules reliably recorded increased cellular motility in the metastatic 1205Lu line as compared with the non-metastatic WM793 line. In a direct comparison of the two propriety DHC software modules and two established transwell assays, the relative cell motilities were well correlated. The granularity of data provided by the Track Cells module permitted the additional identification of rare hyper-motile cells in the metastatic population and the distinction of motility from division associated displacement. The two HoloMonitor M4 DHC proprietary software modules for assessing cellular motility yielded reproducible results that were well-correlated with established standards. © 2018 International Society for Advancement of Cytometry.

The correlation between ultraviolet radiation of the skin and melanoma incidence in humans is well established. Interestingly, epidemiologic data suggest also a correlation to an increased BMI pointing to metabolic trigger factors in melanoma pathogenesis. To substantiate this connection, we studied the expression of G-protein-coupled receptor 120 (GPR120), a receptor sensitive to unsaturated long-chain free fatty acids in melanoma tissues. One-hundred fourteen tissue sections histologically confirmed as nevi (n=32), primary melanoma (n=39), and melanoma metastasis (n=43) were immunohistochemically stained against GPR120. The staining was evaluated by three trained dermatopathologists and independently scored. Compared with nevi, primary melanoma and melanoma metastasis showed significantly higher levels of GPR120 staining. Only three out of 32 nevi showed strong GPR120 expression [median immunoreactivity-scoring system (IRS) score: 1, range: 0-10], whereas in primary melanomas 14 out of 39 were highly GPR120-positive (median IRS score: 7, range: 0-12) and in melanoma metastasis 27 out of 43 were highly GPR120-positive (median IRS score: 9, range: 0-12). GPR120 expression and tumor thickness (mm) show a statistically significant correlation in primary melanoma (P=0.011). Moreover, GPR120-positive staining was found throughout the epidermis and in sebaceous and sweat glands, which is yet not described. This study identified GPR120 as a novel marker for melanoma, indicating that melanoma cells are sensitive to free fatty acids. It is tempting to speculate that pharmacologically interfering with GPR120 signaling might improve melanoma therapy.

A genotyping procedure based on single-step PCR and subsequent allele-specific hybridization on a hydrogel biochip was developed to address the polymorphisms of HERC2, OCA2, SLC24A4, SLC45A2, TYR, IRF4, MC1R,MITF, PIGU, MYH7B, NCOA6, and CDK10. Amplified gene fragments were fluorescently labeled in PCR, and fluorescent signals from biochip cells were detected to evaluate how efficiently the PCR product formed a perfect duplex with an immobilized probe. The analytical characteristics of hybridization analysis were estimated for several fluorophores with different optical spectra. Cyanine dyes fluorescing in the range of Cy5 and Cy7 were synthesized for the purpose and used as 5'-tags of universal primers in single-step PCR. A Cy7 analog fluorescing in the near infrared range was found to increase the sensitivity of hybridization analysis by producing a lower background signal in the cases where target gene amplification was low.

BackgroundTumor-antigen specific CD4+ T cells are crucial for the efficacy of antibodies that block immune checkpoint proteins in mouse tumor models, but their activities in human tumor immunity are less clear. CD8+ T cells infiltrating human tumors, including those specific for tumor antigens, have been studied using single cell profiling techniques and exist in a variety of dysfunctional states. The transcriptional states of tumor-specific CD4+ T cells present in tumors and their potential contributions to the tumor microenvironment are less well understood.MethodsWe used targeted single cell RNA sequencing and matching of T cell receptor (TCR) sequences to identify phenotypic signatures that discriminated tumor antigen- and viral antigen-specific CD4+ T cells infiltrating human melanoma tumors in four patients. The presence of CD4+ T cells with these signatures was correlated with the number and phenotype of other immune cells in the tumor microenvironment in an extended cohort of 20 patients.ResultsWe identified 259 CD4+ T cells representing 40 different TCR clonotypes specific for 13 neoantigens and 108 cells representing 14 TCR clonotypes specific for self-antigens in four melanoma patients. High expression of CXCL13 defined conventional CD4+ T cells that recognize tumor associated neoantigens and self-antigens from bystander and viral antigen-specific CD4+ T cells. Tumor-reactive CD4+ T cells could be subdivided into clusters expressing memory and T follicular helper markers, and those expressing cytolytic markers and IFN-g. In an extended cohort of 20 patients with melanoma, the frequency of CXCL13+ CD4+ T cells in the tumor microenvironment correlated with the presence and proliferation of CD8+ T cells, the presence and maturation of B cells, the activation of interferon responsive genes in tumor associated macrophages, and patient survival. CD4+ T cells with similar transcriptional signatures were identified in data sets from breast and non-small cell lung cancer, suggesting these markers may enrich for tumor-reactive CD4+ T cells in many cancers.ConclusionsThese results identify a subset of tumor infiltrating conventional CD4+ T cells in melanoma that are enriched for reactivity to tumor antigens and exist in multiple phenotypic states. Correlations of the presence of these cells with the frequency and phenotype of other immune cells suggest roles for these tumor antigen-specific CD4+ T cells in providing CD8+ T cell help, driving recruitment and maturation of B cells, and activating macrophages. Isolating such cells based on their unique phenotype and utilizing them for adoptive therapy could alter the tumor microenvironment for therapeutic benefit.Ethics ApprovalAll Patient samples in this study were obtained from patients who signed informed consent in a study approved by the institutional review board of the Fred Hutchinson Cancer Research Center (protocol #2643).

The Australian plant Acacia ligulata has a number of traditional food and medicinal uses by Australian Aboriginal people, although no bioactive compounds have previously been isolated from this species. Bioassay-guided fractionation of an ethanolic extract of the mature pods of A. ligulata led to the isolation of the two new echinocystic acid triterpenoid saponins, ligulatasides A (1) and B (2), which differ in the fine structure of their glycan substituents. Their structures were elucidated on the basis of 1D and 2D NMR, GC-MS, LC-MS/MS, and saccharide linkage analysis. These are the first isolated compounds from A. ligulata and the first fully elucidated structures of triterpenoid saponins from Acacia sensu stricto having echinocystic acid reported as the aglycone. Compounds 1 and 2 were evaluated for cytotoxic activity against a human melanoma cancer cell line (SK-MEL28) and a diploid fibroblast cell line (HFF), but showed only weak activity. Refereed/Peer-reviewed

Digital holographic cytometry (DHC) permits label-free visualization of adherent cells. Dozens of cellular features can be derived from segmentation of hologram-derived images. However, the accuracy of single cell classification by these features remains limited for most applications, and lack of standardization metrics has hindered independent experimental comparison and validation. Here we identify twenty-six DHC-derived features that provide biologically independent information across a variety of mammalian cell state transitions. When trained on these features, machine-learning algorithms achieve blind single cell classification with up to 95% accuracy. Using classification accuracy to guide platform optimization, we develop methods to standardize holograms for the purpose of kinetic single cell cytometry. Applying our approach to human melanoma cells treated with a panel of cancer therapeutics, we track dynamic changes in cellular behavior and cell state over time. We provide the methods and computational tools for optimizing DHC for kinetic single adherent cell classification.

Purpose Increased expression of the αvβ6 integrin correlates with advanced tumor grade and poor clinical outcome, identifying αvβ6 as a prognostic indicator and an attractive target for molecular imaging. This work investigated the ability of a disulfide-stabilized [64Cu]NOTA-αvβ6 cys-diabody to image αvβ6 expression in vivo using a nu/nu mouse model bearing human melanoma xenografts and positron-emission tomography.

Di-peptides derived from the human host defense peptide lactoferricin were previously described to specifically interact with the negatively charged lipid phosphatidylserine exposed by cancer cells. In this study one further derivative, namely R-DIM-P-LF11-334 is shown to exhibit even increased cancer toxicity in vitro and in vivo while non-neoplastic cells are not harmed. In liposomal model systems composed of phosphatidylserine mimicking cancerous and phosphatidylcholine mimicking non-cancerous membranes the specific interaction with the cancer marker PS was confirmed by specific induction of membrane perturbation and permeabilization in presence of the peptide. In vitro studies with cell lines of human malignant melanoma, such as A375, or primary cells of human melanoma metastases to the brain, as MUG Mel1, and non-neoplastic human dermal fibroblasts NHDF revealed high cytotoxic effect of R-DIM-P-LF11-334 on melanoma cells of A375 and MUG Mel1, whereas only minor effect on the dermal fibroblasts NHDF was observed, yielding an about 20-fold killing-specificity for A375 and MUG-Mel1. The LC50 values for melanoma A375 and MUG Mel1 were about 10 μM. Analysis of secondary structure of the peptide revealed an increase in the proportion of β-sheets exclusively in presence of the cancer mimic. Stability studies further indicated a potential adequate stability in blood or under stringent conditions. Importantly the cytotoxic effect on cancer cells was also proven in vivo in mouse xenografts of human melanoma, where peptide treatment induced strong tumor regression and in average a tumor area reduction of 85% compared to tumors of control mice without peptide treatment.

// Hana Andrlova 1 , Justin Mastroianni 1 , Josef Madl 2, 3 , Johannes S. Kern 4 , Wolfgang Melchinger 1 , Heide Dierbach 1 , Florian Wernet 1 , Marie Follo 1 , Kristin Technau-Hafsi 4 , Cristina Has 4 , Venugopal Rao Mittapalli 4 , Marco Idzko 5 , Ricarda Herr 6 , Tilman Brummer 6 , Hendrik Ungefroren 7 , Hauke Busch 7, 8, 9, 15 , Melanie Boerries 6, 8, 15 , Andreas Narr 10, 11 , Gabriele Ihorst 12 , Claire Vennin 13 , Annette Schmitt-Graeff 14 , Susana Minguet 10, 11 , Paul Timpson 13 , Justus Duyster 1 , Frank Meiss 4 , Winfried Romer 2, 3 and Robert Zeiser 1, 3 1 Department of Hematology and Oncology, University Medical Center, Faculty of Medicine, Freiburg, Germany 2 Faculty of Biology, Albert Ludwigs University, Freiburg, Germany 3 BIOSS Centre for Biological Signalling Studies, Albert Ludwigs University Freiburg, Freiburg, Germany 4 Department of Dermatology and Venereology, University Medical Center, Freiburg, Germany 5 Department of Pneumology, University Medical Center, Freiburg, Germany 6 Institut fur Molekulare Medizin und Zellforschung, University Medical Center, Freiburg, Germany 7 First Department of Medicine, University of Lubeck, Lubeck, Germany 8 German Cancer Consortium (DKTK), Freiburg, Germany 9 Institute of Experimental Dermatology, University of Lubeck, Lubeck, Germany 10 Department of Immunology, BIOSS Center for Biological Signaling Studies, Faculty of Biology, Albert-Ludwigs-University of Freiburg, Freiburg, Germany 11 Center of Chronic Immunodeficiency CCI, University Clinics and Medical Faculty, Freiburg, Germany 12 Clinical Trials Unit, University Medical Center, Freiburg, Germany 13 The Garvan Institute of Medical Research and The Kinghorn Cancer Centre, Sydney, Australia 14 Department of Pathology, University Medical Center, Faculty of Medicine, Freiburg, Germany 15 German Cancer Research Center (DKFZ), Heidelberg, Germany Correspondence to: Robert Zeiser, email: robert.zeiser@uniklinik-freiburg.de Keywords: biglycan, melanoma, microenvironment, tissue stiffness, integrin-β1 Received: October 04, 2016 Accepted: March 14, 2017 Published: April 17, 2017 ABSTRACT Novel targeted and immunotherapeutic approaches have revolutionized the treatment of metastatic melanoma. A better understanding of the melanoma-microenvironment, in particular the interaction of cells with extracellular matrix molecules, may help to further improve these new therapeutic strategies. We observed that the extracellular matrix molecule biglycan (Bgn) was expressed in certain human melanoma cells and primary fibroblasts when evaluated by microarray-based gene expression analysis. Bgn expression in the melanoma tissues correlated with low overall-survival and low progression-free-survival in patients. To understand the functional role of Bgn we used gene-targeted mice lacking functional Bgn. Here we observed that melanoma growth, metastasis-formation and tumor-related death were reduced in Bgn -/- mice compared to Bgn +/+ mice. In vitro invasion of melanoma cells into organotypic-matrices derived from Bgn -/- fibroblasts was reduced compared to melanoma invasion into Bgn -proficient matrices. Tissue stiffness as determined by atomic-force-microscopy was reduced in Bgn -/- matrices. Isolation of melanoma cells and fibroblasts from the stiffer Bgn +/+ matrices revealed an increase in integrin-β1 expression compared to the Bgn -/- fibroblast matrices. Overexpression of integrin-β1 in B16-melanoma cells abolished the survival benefit seen in Bgn -/- mice. Consistent with the studies performed in mice, the abundance of Bgn-expression in human melanoma samples positively correlated with the expression of integrin-β1, which is in agreement with results from the organotypic invasion-assay and the in vivo mouse studies. This study describes a novel role for Bgn-related tissue stiffness in the melanoma-microenvironment via regulation of integrin-β1 expression by melanoma cells in both mice and humans.