Melanocyte Differentiation Research Articles

Research progress in melanogenesis signaling pathway

Melanogenesis is a biosynthetic pathway to produce melanin pigment in melanocyte, involving a series of intricate enzymatic and chemical catalyzed reactions. Melanogenesis involves five signaling pathways that converge on microphthalmia-associated transcription factor. In addition, many cytokines, involved in the regulation of melanogenesis, play an important role in the development, proliferation, differentiation and migration of melanocytes. Polyoxometalate can be used as a potential inhibitor of melanin production. Hence, this paper reviews the signaling pathways of melanogenesis and their regulatory mechanism, to apply polyoxometalates in the melanin production pathway, and briefly introduces the regulatory factors of related pathways.

Characterization of boscalid-induced oxidative stress and neurodevelopmental toxicity in zebrafish embryos

Boscalid is a widely used fungicide in agriculture and has been frequently detected in both environments and agricultural products. However, evidence on the neurotoxic effect of boscalid is scarce. In this study, zebrafish served as an animal model to investigate the toxic effects and mechanisms of boscalid on aquatic vertebrates or higher animals. And we unravelled that boscalid induced developmental defects associated with oxidative stress. Developmental defects, including head deformity, hypopigmentation, decreased number of newborn neurons, structural defects around the ventricle, enlarged intercellular space in the brain, and nuclear concentration, were observed in zebrafish embryos after boscalid exposure at 48 hpf. Interestingly, we found that boscalid might directly induce oxidative stress and alter the activity of ATPase, which in turn disrupted the expression of genes involved in neurodevelopment and transmitter-transmitting signalings and melanocyte differentiation and melanin synthesis signalings. Ultimately, the differentiation of nerve cells and melanocytes were both impacted and the synthesis of melanin was inhibited, leading to morphological abnormalities. Additionally, exposure to boscalid led to less and imbalance motion and altered tendency of locomotor in larval fish. Collectively, our results provide new evidences for a comprehensive assessment of its toxicity and a warning for its residues in environment and agricultural products.

Syngeneic B16-F1 cells are more efficient than allogeneic Cloudman cells as antigen source in DC-based vaccination in the B16-F1 murine melanoma model

A major obstacle to obtaining relevant results in cancer vaccination has been the lack of identification of immunogenic antigens. Dendritic cell (DC)-based cancer vaccines used preventively may afford protection against tumor inoculation, but the effect of antigen choice on anti-tumor protection is not clear. When using irradiated syngeneic tumor cells to load DCs, tumor self-antigens are provided, including tumor-associated antigens (TAAs) and neoantigens generated by tumor mutations. On the other hand, allogeneic tumor cells could only supply shared TAAs. To assess the advantages of each source in protective vaccination, we analyzed in C57BL/6 mice the effect of loading DCs with irradiated syngeneic B16-F1 or allogeneic Cloudman melanoma cells; both cell lines were characterized by whole exome sequencing and RNAseq. Tumor cell components from the two irradiated cell lines were efficiently internalized by DCs, and transported to MHC-class II positive tubulovesicular compartments (MIICs). DCs loaded with allogeneic irradiated Cloudman cells (DC-ApoNecALLO) induced a partially effective anti-melanoma protection, although Cloudman and B16-F1 cells share the expression of melanocyte differentiation antigens (MDAs), cancer-testis antigens (CTAs) and other TAAs. DCs loaded with syngeneic B16-F1 cells (DC-ApoNecSYN) established a more potent and long-lasting protection and induced a humoral anti-B16F1 response, thus suggesting that neoepitopes are needed for inducing long-lasting protection.

Abstract 1049A: Deregulation of MITF in the context of inactive MC1R leads to melanocyte transformation

Abstract MC1R, the cAMP pathway and the response to solar UV are all elements involved in the growth, differentiation and survival of melanocytes and in malignant melanoma. Here we present a model of melanomagenesis based on the forced expression of MITF-M in the context of MC1R-inactivating variants in a way not dependent on sun exposure. We demonstrate that lentiviral transduction of MITF-M alone leads to consistent transformation of the Hermes4C cell line with inactive MC1R, but not the Hermes3C cell line having a wild type background. Hermes 4c cells transduced with MITF-M are able to form tumors in mice. We mapped MITF binding to chromatin and found that 4C cells displayed enhanced MITF chromatin binding compared to 3C. Expression analysis revealed that the altered binding pattern leads to enhanced transcription of epithelial to mesenchymal transition genes and consequent repression of key melanocyte-specific genes e.g. involved in pigmentation in the background of inactive MC1R. We observed a marked deregulation of AXL and EGFR, which is accompanied by downregulation of PTEN and increased phosphorylation of ERK and PI3K-AKT pathway. In conclusion, we show that MITF-M is a molecular switch in the context of MC1R-inactivating variant which leads to cell reprogramming and melanomagenesis. Citation Format: Tine Norman Alver, Timothy J. Lavelle, Karen-Marie Heintz, Patrik Wernhoff, Vegard Nygaard, Geir F. Øy, Sigurd L. Bøe, Alfonso Urbanucci, Eivind J. Hovig. Deregulation of MITF in the context of inactive MC1R leads to melanocyte transformation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1049A.

Abstract 5010: Potentiating immune checkpoint blockade therapeutic efficacy using a small molecule activator of integrin cell adhesion receptors

Abstract Background: Immune checkpoint blockade (ICB) has therapeutic benefit in several human cancers, but in many patients, ICB - induced T cells do not infiltrate tumors, preventing clinical benefit. Intratumoral T cell accumulation requires firm adhesion mediated by the integrins very late antigen-4 (VLA-4) and lymphocyte function-associated antigen-1 (LFA-1) on activated T cells. The integrin class of cell adhesion receptors also play critical roles in multiple phases of tumor immune responses. Blocking the LFA-1 interaction with its ligand Intercellular adhesion molecule 1 (ICAM-1) abrogates CD8+ tumor infiltration after anti-CTLA4 therapy. Here, we evaluated the effect of an integrin activator, 7HP349, on promoting intratumoral T cell accumulation to potentiate CTLA-4 and PD-L1 checkpoint blockade anti-tumor activity. Experimental Procedure: To evaluate the effect of 7HP349 in promoting ICB therapeutic activity, we combined 7HP349 with anti-CTLA-4 or anti-PD-L1 antibodies in preclinical murine models for melanoma and colon carcinoma. Results: In cell adhesion assays, 7HP349 increased by >100-fold the number of VLA-4 or LFA-1 expressing T cells that bind to vascular cell adhesion molecule 1 (VCAM-1) and ICAM-1, respectively. 7HP349 facilitated chemo-attraction of T cells across matrices of VCAM-1 or ICAM-1, induced by the chemokine SDF-1α. In a PDL-1 negative B16/BL6 melanoma model, 7HP349 was dosed twice weekly at 1 mg/Kg intratumorally either alone as a single agent compared to vehicle control (13% vs 0%, p<0.01) or in combination with anti-CTLA-4 (44% vs 21%, p<0.01). After intraperitoneal administration, 7HP349 increased the complete response in combinations with anti-CTLA-4 (77% vs 27%, p<0.01). In addition, 7HP349 increased median survival in mice with CT-26 colon cancer when dosed either as a single agent versus control (21 vs 15 days, P<0.0012) or in combination with anti-PD-L1 (24 vs 21 days, P<0.02). 7HP349 may also increase the effectiveness of anti-CD137 without increasing liver toxicity. Levels of CD8 effector T cells (Teff) detected in tumor were significantly higher in mice treated with anti-CTLA-4 and 7HP349 than anti-CTLA-4 and vehicle. Some of these Teff showed specificity to p15E, an endogenous retroviral epitope expressed on B16. Mice treated with anti-CTLA-4 and 7HP349 showed increased depigmentation (vitiligo) suggesting immunity to melanocyte differentiation antigens. Conclusion: 7HP349 described here represents a first-in-concept agent that positively regulate VLA-4 and LFA-1 function. Activation of integrin cell adhesion molecules with 7HP349 is a promising approach to enhance the anti-cancer activity of checkpoint blockade therapy with antibodies against CTLA-4 and PD-(L)1. Citation Format: Yared Hailemichael, Peter Vanderslice, Robert V. Market, Ronald J. Biediger, Darren G. Woodside, Upendra K. Marathi, Willem W. Overwijk. Potentiating immune checkpoint blockade therapeutic efficacy using a small molecule activator of integrin cell adhesion receptors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5010.

Early prediction of the differentiation potential during the formation of human iPSC-derived embryoid bodies

Induced pluripotent stem cells (iPSCs) show huge variations in their differentiation potential, even in the same condition. However, methods for predicting these differentiation tendencies, especially in the early stage of differentiation, are still scarce. This study aimed to establish a simple and practical system to predict the differentiation tendency of iPSC lines using embryoid bodies (EBs) with identified parameters in the early stage. We compared four human iPSC lines in terms of the morphology and maintenance of EBs and their gene expression levels of specific markers for three germ-layers. Furthermore, the differentiation potentials of these iPSC lines into melanocytes, which are ectoderm-derived cells, were also compared and correlated with the above parameters. The results showed that iPSC lines forming regular, smooth, and not cystic EBs, which could be maintained in culture for a relatively longer time, also expressed higher levels of ectoderm-specific markers and lower levels of mesoderm/endoderm markers. Additionally, these iPSC lines showed greater potential in melanocyte differentiation using EB-based protocol, and the induced melanocytes expressed melanocytic markers and presented characteristics that were similar to those of normal human melanocytes. By contrast, iPSC lines that formed cystic EBs with bright or dark cavities and expressed relatively lower levels of ectoderm-specific markers failed in the melanocyte differentiation. Collectively, the differentiation tendency of human iPSC lines may be predicted by specific parameters in the EB stage. The formation and maintenance of optimal EBs and the expression of germ layer-specific markers are particularly important and practical for the prediction assay in the early stage.

The gene regulatory basis of genetic compensation during neural crest induction.

The neural crest (NC) is a vertebrate-specific cell type that contributes to a wide range of different tissues across all three germ layers. The gene regulatory network (GRN) responsible for the formation of neural crest is conserved across vertebrates. Central to the induction of the NC GRN are AP-2 and SoxE transcription factors. NC induction robustness is ensured through the ability of some of these transcription factors to compensate loss of function of gene family members. However the gene regulatory events underlying compensation are poorly understood. We have used gene knockout and RNA sequencing strategies to dissect NC induction and compensation in zebrafish. We genetically ablate the NC using double mutants of tfap2a;tfap2c or remove specific subsets of the NC with sox10 and mitfa knockouts and characterise genome-wide gene expression levels across multiple time points. We find that compensation through a single wild-type allele of tfap2c is capable of maintaining early NC induction and differentiation in the absence of tfap2a function, but many target genes have abnormal expression levels and therefore show sensitivity to the reduced tfap2 dosage. This separation of morphological and molecular phenotypes identifies a core set of genes required for early NC development. We also identify the 15 somites stage as the peak of the molecular phenotype which strongly diminishes at 24 hpf even as the morphological phenotype becomes more apparent. Using gene knockouts, we associate previously uncharacterised genes with pigment cell development and establish a role for maternal Hippo signalling in melanocyte differentiation. This work extends and refines the NC GRN while also uncovering the transcriptional basis of genetic compensation via paralogues.

Oculocutaneous Albinism with Squamous Cell Carcinoma, Bowen's Disease and Actinic Keratosis: A Case Report

Oculocutaneous Albinism with Squamous Cell Carcinoma, Bowen's Disease and Actinic Keratosis: A Case Report

Systematic assessment of LCMV based vaccine vectors expressing melanocyte differentiation antigens in human in vitro assays and in mouse melanoma models.

e14299 Background: Antibodies blocking the immune checkpoint pathways represent an important milestone in the treatment of patients with metastatic melanoma. However, individuals presenting cold tumors do usually not show a clinical benefit. New cancer vaccine approaches are needed to cover this gap. Methods: A novel replication attenuated vaccine vector based on lymphocytic choriomeningitis virus expressing full length melanocyte differentiation antigens is evaluated in mouse melanoma models and in PBMCs and T cell cultures from melanoma patients. Results: Here, we demonstrate that intratumoral but not intravenous injection of a recombinant propagating LCMV vector expressing the melanoma-associated antigen TRP2 leads to T cell-dependent eradication of established s.c. melanoma. Importantly, intratumoral vaccination shows an abscopal effect on distant lung metastasis and protects from a rechallenge with melanoma. Confocal microscopy and flow cytometry reveal that intratumoral injection of rLCMV vectors reprograms the tumor microenvironment resulting in sustained T cell fitness. In addition, we demonstrate that rLCMV vectors can efficiently transduce human antigen presenting cells. Moreover, in vitro data confirm that rLCMV efficiently induces T cells against various melanoma-associated antigens in PBMCs from melanoma patients. Conclusions: Preclinical assessment of propagating rLCMV vectors shows unique features of this cancer vaccine resulting in a profound and multistep activation of the cancer immunity cycle resulting in eradication of established melanomas in the B16F10 mouse model after one single immunization. Positive proof of principle experiments using PBMCs from melanoma patients suggest a rapid evaluation in clinical trials.

Rottlerin Reduces cAMP/CREB-Mediated Melanogenesis via Regulation of Autophagy.

Melanogenesis is the sequential process of melanin production by melanocytes in order to protect the skin from harmful stimuli. Melanogenesis is disrupted by radiation exposure, which results in the differentiation of melanocytes into melanoma. Recently, some methods have been developed to maintain the instability of melanogenesis in melanoma by activating cellular autophagy. However, there is still a lack of knowledge about how autophagy is involved in the regulation of melanogenesis in melanoma cells. Here, we used rottlerin as an autophagy inducer to investigate the role of the cyclic adenosine monophosphate (cAMP)/cAMP response element binding (CREB) signaling pathway in melanogenesis. We found that rottlerin can inhibit melanin production by targeting cAMP, which is initially activated by alpha-melanocyte stimulating hormone (α-MSH). Our findings suggest that rottlerin has a pivotal role as an autophagy inducer in the regulation of melanogenesis by targeting the cAMP/CREB signaling pathway.

CD34 defines melanocyte stem cell subpopulations with distinct regenerative properties.

Melanocyte stem cells (McSCs) are the undifferentiated melanocytic cells of the mammalian hair follicle (HF) responsible for recurrent generation of a large number of differentiated melanocytes during each HF cycle. HF McSCs reside in both the CD34+ bulge/lower permanent portion (LPP) and the CD34- secondary hair germ (SHG) regions of the HF during telogen. Using Dct-H2BGFP mice, we separate bulge/LPP and SHG McSCs using FACS with GFP and anti-CD34 to show that these two subsets of McSCs are functionally distinct. Genome-wide expression profiling results support the distinct nature of these populations, with CD34- McSCs exhibiting higher expression of melanocyte differentiation genes and with CD34+ McSCs demonstrating a profile more consistent with a neural crest stem cell. In culture and in vivo, CD34- McSCs regenerate pigmentation more efficiently whereas CD34+ McSCs selectively exhibit the ability to myelinate neurons. CD34+ McSCs, and their counterparts in human skin, may be useful for myelinating neurons in vivo, leading to new therapeutic opportunities for demyelinating diseases and traumatic nerve injury.

Comparative transcriptome analysis reveals the genetic basis of coat color variation in Pashmina goat

The genetics of coat color variation remains a classic area. Earlier studies have focused on a limited number of genes involved in color determination; however, the complete set of trait determinants are still not well known. In this study, we used high-throughput sequencing technology to identify and characterize intricate interactions between genes that cause complex coat color variation in Changthangi Pashmina goats, producer of finest and costly commercial animal fiber. We systematically identified differentially expressed mRNAs and lncRNAs from black, brown and white Pashmina goat skin samples by using RNA-sequencing technique. A pairwise comparison of black, white and brown skin samples yielded 2479 significantly dysregulated genes (2422 mRNA and 57 lncRNAs). Differentially expressed genes were enriched in melanin biosynthesis, melanocyte differentiation, developmental pigmentation, melanosome transport activities GO terms. Our analysis suggested the potential role of lncRNAs on color coding mRNAs in cis and trans configuration. We have also developed online data repository as a component of the study to provide a central location for data access, visualization and interpretation accessible through http://pcd.skuastk.org/.

151 Investigating BMP signaling as a therapeutic target in advanced melanoma

Melanoma is the leading cause of skin cancer death in the United States, with a 5-year survival rate of 20% for patients with advanced disease. The development of targeted therapies and immunotherapy has helped improve survival for some patients, but many others still face significant therapeutic challenges, including resistance to therapy and relapse of their disease. Furthermore, our understanding of the steps involved in melanoma initiation and progression is incomplete. We are interested in uncovering factors involved in melanoma initiation and progression with a focus on identifying those key factors that have therapeutic potential. Previously, we identified a novel melanoma oncogene, growth differentiation factor 6 (GDF6), a bone morphogenetic protein (BMP) ligand that promotes melanoma by suppressing differentiation and apoptosis. We have shown that the dedifferentiation effects are mediated by suppression of MITF, the master regulator of melanocyte differentiation, and the anti-apoptotic effects of GDF6 are mediated by suppression of SOX9, a pro-apoptotic factor in melanoma. These results establish GDF6-activated BMP signaling may play a significant role during melanoma progression. Here, we further establish BMP activity impacts melanocyte development and may have therapeutic value in established disease. We find that GDF6 inhibits embryonic melanocyte differentiation from the neural crest, suggesting that its function in melanoma to maintain a dedifferentiated state is a reiteration (or reawakening) of its role in early development. We further identify novel anti-GDF6 therapeutic antibodies that exhibit anti-melanoma activity in vitro, indicating inhibition of GDF6-activated BMP signaling is a potential therapeutic approach for advanced melanoma. Together, these results indicate the importance of GDF6-activated BMP signaling in the development of the melanocyte lineage and melanoma, and provide evidence for targeting BMP signaling as a therapeutic approach in advanced melanoma.

814 RHOJ knockdown modulates the migration and differentiation of normal human melanocytes and the expression of pro-apoptotic markers after UV exposure

814 RHOJ knockdown modulates the migration and differentiation of normal human melanocytes and the expression of pro-apoptotic markers after UV exposure

Variation in pigmentation gene expression is associated with distinct aposematic color morphs in the poison frog Dendrobates auratus

BackgroundColor and pattern phenotypes have clear implications for survival and reproduction in many species. However, the mechanisms that produce this coloration are still poorly characterized, especially at the genomic level. Here we have taken a transcriptomics-based approach to elucidate the underlying genetic mechanisms affecting color and pattern in a highly polytypic poison frog. We sequenced RNA from the skin from four different color morphs during the final stage of metamorphosis and assembled a de novo transcriptome. We then investigated differential gene expression, with an emphasis on examining candidate color genes from other taxa.ResultsOverall, we found differential expression of a suite of genes that control melanogenesis, melanocyte differentiation, and melanocyte proliferation (e.g., tyrp1, lef1, leo1, and mitf) as well as several differentially expressed genes involved in purine synthesis and iridophore development (e.g., arfgap1, arfgap2, airc, and gart).ConclusionsOur results provide evidence that several gene networks known to affect color and pattern in vertebrates play a role in color and pattern variation in this species of poison frog.

SOX10 regulates multiple genes to direct eumelanin versus pheomelanin production in domestic rock pigeon.

The domesticated rock pigeon (Columba livia) has been bred for hundreds of years to display an immense variety of ornamental attributes such as feather color and color patterns. Color is influenced by multiple loci that impact the type and amount of melanin deposited on the feathers. Pigeons homozygous for the “recessive red” mutation, which causes downregulation of Sox10, display brilliant red feathers instead of blue/black feathers. Sox10 encodes a transcription factor important for melanocyte differentiation and function, but the genes that mediate its promotion of black versus red pigment are unknown. Here, we present a transcriptomic comparison of regenerating feathers from wild‐type and recessive red pigeons to identify candidate SOX10 targets. Our results identify both known and novel targets, including many genes not previously implicated in pigmentation. These data highlight the value of using novel, emerging model organisms to gain insight into the genetic basis of pigment variation.

Quantification of Hypopigmentation Activity In Vitro.

This study presents laboratory methods for the quantification of hypopigmentation activity in vitro. Melanin, the major pigment in melanocytes, is synthesized in response to multiple cellular and environmental factors. Melanin protects skin cells from ultraviolet damage, but also has biophysical and biochemical functions. Excessive production or accumulation of melanin in melanocytes can cause dermatological problems, such as freckles, dark spots, melasma, and moles. Therefore, the control of melanogenesis with hypopigmentation agents is important in individuals with clinical or cosmetic needs. Melanin is primarily synthesized in the melanosomes of melanocytes in a complex biochemical process called melanogenesis, which is influenced by extrinsic and intrinsic factors, such as hormones, inflammation, age, and ultraviolet light exposure. We describe three methods to determine the hypopigmentation activity of chemicals or natural substances in melanocytes: measurement of the 1) cellular tyrosinase activity and 2) melanin content, and 3) staining and quantifying cellular melanin with image analysis. In melanogenesis, tyrosinase catalyzes the rate-limiting step that converts L-tyrosine into 3,4-dihydroxyphenylalanine (L-DOPA) and then into dopaquinone. Therefore, the inhibition of tyrosinase is a primary hypopigmentation mechanism. In cultured melanocytes, tyrosinase activity can be quantified by adding L-DOPA as a substrate and measuring dopaquinone production by spectrophotometry. Melanogenesis can also be measured by quantifying the melanin content. The melanin-containing cellular fraction is extracted with NaOH and melanin is quantified spectrophotometrically. Finally, the melanin content can be quantified by image analysis following Fontana-Masson staining of melanin. Although the results of these in vitro assays may not always be reproduced in human skin, these methods are widely used in melanogenesis research, especially as the initial step to identify potential hypopigmentation activity. These methods can also be used to assess melanocyte activity, growth, and differentiation. Consistent results with the three different methods ensure the validity of the effects.

Dicer1 is required for pigment cell and craniofacial development in zebrafish

The multidomain RNase III endoribonuclease DICER is required for the generation of most functional microRNAs (miRNAs). Loss of Dicer affects developmental processes at different levels. Here, we characterized the zebrafish Dicer1 mutant, dicer1sa9205, which has a single point mutation induced by N-ethyl-N-nitrosourea mutagenesis. Heterozygous dicer1sa9205 developed normally, being phenotypically indistinguishable from wild-type siblings. Homozygous dicer1sa9205 mutants display smaller eyes, abnormal craniofacial development and aberrant pigmentation. Reduced numbers of both iridophores and melanocytes were observed in the head and ventral trunk of dicer1sa9205 homozygotes; the effect on melanocytes was stronger and detectable earlier in development. The expression of microphthalmia-associated transcription factor a (mitfa), the master gene for melanocytes differentiation, was enhanced in dicer1-depleted fish. Similarly, the expression of SRY-box containing gene 10 (sox10), required for mitfa activation, was higher in mutants than in wild types. In silico and in vivo analyses of either sox10 or mitfa 3’UTRs revealed conserved potential miRNA binding sites likely involved in the post-transcriptional regulation of both genes. Based on these findings, we propose that dicer1 participates in the gene regulatory network governing zebrafish melanocyte differentiation by controlling the expression of mitfa and sox10.

Antibodies as biomarker candidates for response and survival to checkpoint inhibitors in melanoma patients

BackgroundLong-term survival of stage IV melanoma patients has improved significantly with the development of immune checkpoint inhibitors (CIs). Reliable biomarkers to predict response and clinical outcome are needed.MethodsWe investigated the role of melanoma-associated antibodies as predictive markers for CI therapy in two independent cohorts. In cohort 1, a prospective study, we measured specific antibodies before treatment, after one week and after six to nine weeks of treatment. Cohort 2 consisted of serum samples prior to CI therapy initiation. ELISA assays were performed to quantify specific IgG directed against melanocyte differentiation antigens tyrosinase-related proteins 1 and 2 (TRP1/TYRP1 and TRP2/TYRP2), glycoprotein 100 (gp100), MelanA/MART1, and the cancer-testis antigen NY-ESO-1. Response was defined as either complete or partial remission on CT scan according to RECIST 1.1.ResultsIn cohort 1, baseline levels of these antibodies were higher in the responder group, although statistical significance was only reached for NY-ESO-1 (p = 0.007). In cohort 2, significantly higher antibody baseline levels for MelanA/MART1 (p = 0.003) and gp100 (p = 0.029) were found. After pooling the results from both cohorts, higher levels of MelanA/MART1 (p = 0.013), TRP1/TYRP1 (p = 0.048), TRP2/TYRP2 (p = 0.047) and NY-ESO-1 (p = 0.005) specific antibodies at baseline were independently associated with response.ConclusionsMelanoma-associated antibodies may be candidate biomarkers for response and survival in metastatic melanoma patients being treated with CIs. These markers may be used to complement patient assessment, in combination with PD-L1 status, tumor-infiltrating lymphocytes and tumor mutational burden, with the aim to predict outcome of CI treatment in patients with metastatic melanoma.Trial registrationEthikkommission Ostschweiz, EKOS 16/079 https://ongoingprojects.swissethics.ch/runningProjects_list.php?q=%28BASECID~contains~2016-00998%29&orderby=dBASECID.

Reprogramming Captures the Genetic and Tumorigenic Properties of Neurofibromatosis Type 1 Plexiform Neurofibromas.

SummaryNeurofibromatosis type 1 (NF1) is a tumor predisposition genetic disease caused by mutations in the NF1 tumor suppressor gene. Plexiform neurofibromas (PNFs) are benign Schwann cell (SC) tumors of the peripheral nerve sheath that develop through NF1 inactivation and can progress toward a malignant soft tissue sarcoma. There is a lack of non-perishable model systems to investigate PNF development. We reprogrammed PNF-derived NF1(−/−) cells, descendants from the tumor originating cell. These NF1(−/−)-induced pluripotent stem cells (iPSCs) captured the genomic status of PNFs and were able to differentiate toward neural crest stem cells and further to SCs. iPSC-derived NF1(−/−) SCs exhibited a continuous high proliferation rate, poor myelination ability, and a tendency to form 3D spheres that expressed the same markers as their PNF-derived primary SC counterparts. They represent a valuable model to study and treat PNFs. PNF-derived iPSC lines were banked for making them available.