Neural Crest Progenitor Cells Research Articles

A bioinformatics approach to reveal common genes and molecular pathways shared by cutaneous melanoma and uveal melanoma

Background Melanomas are highly aggressive in nature known for metastasis and death. Melanocytes that gave rise to melanomas are neural crest progenitor cells. Our research was primarily concerned with uveal melanoma (UM) and cutaneous melanoma (CM), respectively. Although they both have the same melanocytic origin, the biology of their respective is different.Aim The aim of our study was to recognize the common differentially expressed genes (DEGs) between UM and CM.MethodologyThe gene expression profile was downloaded from the GEO and analyzed by GEO2R to recognize DEGs. By applying DAVID, GO, and KEGG, pathway enrichment analysis was performed. PPI of these DEGs was analyzed using STRING and visualized by Cytoscape and MCODE. Further, we utilized HPA and GEPIA to obtain Kaplan–Meier graph for survival analysis in order to assess the prognostic value of hub genes.Results We examined the UM and CM datasets and discovered three common upregulated and eight downregulated DEGs based on computational analysis. HMGCS1 and ELOVL5 were shown to be enriched in a variety of altered molecular pathways and pathways in cancer. Overexpression of HMGCS1 and ELOVL5 was linked to a poor prognosis in CM.Conclusion Computational evaluation found that HMGCS1 and ELOVL5 were upregulated in both melanomas. Enrichment analysis showed that these genes are involved in cancer metabolism pathway and associated with poor prognosis in CM. However, the molecular study of these genes in UM is limited. Therefore, a better understanding of the cancer metabolism pathways should be carried to pave the way for clinical benefits.

Augmentation of BMP Signaling in Cranial Neural Crest Cells Leads to Premature Cranial Sutures Fusion through Endochondral Ossification in Mice.

Craniosynostosis is a congenital anomaly characterized by the premature fusion of cranial sutures. Sutures are a critical connective tissue that regulates bone growth; their aberrant fusion results in abnormal shapes of the head and face. The molecular and cellular mechanisms have been investigated for a long time, but knowledge gaps remain between genetic mutations and mechanisms of pathogenesis for craniosynostosis. We previously demonstrated that the augmentation of bone morphogenetic protein (BMP) signaling through constitutively active BMP type 1A receptor (caBmpr1a) in neural crest cells (NCCs) caused the development of premature fusion of the anterior frontal suture, leading to craniosynostosis in mice. In this study, we demonstrated that ectopic cartilage forms in sutures prior to premature fusion in caBmpr1a mice. The ectopic cartilage is subsequently replaced by bone nodules leading to premature fusion with similar but unique fusion patterns between two neural crest-specific transgenic Cre mouse lines, P0-Cre and Wnt1-Cre mice, which coincides with patterns of premature fusion in each line. Histologic and molecular analyses suggest that endochondral ossification in the affected sutures. Both in vitro and in vivo observations suggest a greater chondrogenic capacity and reduced osteogenic capability of neural crest progenitor cells in mutant lines. These results suggest that the augmentation of BMP signaling alters the cell fate of cranial NCCs toward a chondrogenic lineage to prompt endochondral ossification to prematurely fuse cranial sutures. By comparing P0-Cre;caBmpr1a and Wnt1-Cre;caBmpr1a mice at the stage of neural crest formation, we found more cell death of cranial NCCs in P0-Cre;caBmpr1a than Wnt1-Cre;caBmpr1a mice at the developing facial primordia. These findings may provide a platform for understanding why mutations of broadly expressed genes result in the premature fusion of limited sutures. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

C1GALT1 expression predicts a favorable prognosis and suppresses malignant phenotypes via TrkA signaling in neuroblastoma

Neuroblastoma (NB) is a childhood tumor derived from the sympathoadrenal lineage of the neural crest progenitor cells. Core 1 β1,3-galactosyltransferase (C1GALT1) controls the crucial step of GalNAc-type O-glycosylation, and its altered expression affects cancer behaviors. However, the role of C1GALT1 in NB tumors remains unclear. Our data showed that C1GALT1 expression was significantly associated with differentiated tumor histology, correlated with TrkA expression, and predicted good prognosis independently in NB. Downregulation of C1GALT1 promotes malignant behaviors of NB cells in vitro and in vivo. Mechanistic investigation showed that knockdown of C1GALT1 in NB cells increased TrkA pulled down through Vicia villosa agglutinin beads, indicating the modulation of O-glycans on TrkA by C1GALT1, and silencing C1GALT1 suppressed the TrkA expression on the NB cell surface. Overexpression of C1GALT1 increased the protein levels of TrkA and promoted the differentiation of NB cells, whereas knockdown of TrkA inhibited C1GALT1-induced neuronal differentiation. Moreover, the inhibitory effects of migration and invasion in C1GALT1-overexpressing NB cells were blocked by TrkA downregulation. C1GALT1 knockdown enhanced AKT phosphorylation but attenuated ERK phosphorylation, and these properties were consistent in C1GALT1-overexpressing NB cells with TrkA knockdown. Taken together, our data provided the first evidence for the existence of GalNAc-type O-glycans on TrkA and altered O-glycan structures by C1GALT1 can regulate TrkA signaling in NB cells. This study sheds light on the novel prognostic role of C1GALT1 in NB and provides new information of C1GALT1 and TrkA on the pathogenesis of NB.

Metal transporter Slc30a1 controls pharyngeal neural crest differentiation via the zinc-Snai2-Jag1 cascade.

The pharyngeal arch (PA) is a neural crest (NC)‐derived organ that is transiently developed during embryogenesis and is required for the subsequent development of various tissues. However, the role of zinc during PA differentiation from NC progenitor cells is unknown. Here, we found that the metal transporters Slc30a1a and Slc30a1b mediate zinc homeostasis during PA differentiation. Slc30a1‐deficient zebrafish develop zinc accumulation in NC cells, with increased expression of stemness markers and PA dorsal genes, and SMART‐seq analyses revealed that the genes snai2 and jag1b may serve as downstream targets. Furthermore, functional studies showed that knocking down either snai2 or jag1b rescues PA development in Slc30a1‐deficient zebrafish. Notably, we identified the double zinc‐finger domain in the transcription factor Snai2 as a zinc‐responsive element that regulates jag1b expression. Our findings indicate that the Slc30a1/zinc‐snai2‐jag1b axis is an essential regulatory network controlling PA differentiation, shedding new light on the function of zinc homeostasis in maintaining NC cell stemness and multipotency in vertebrates.

FOXD3 suppresses epithelial-mesenchymal transition through direct transcriptional promotion of SMAD7 in esophageal squamous cell carcinoma.

The transcription factor forkhead box D3 (FOXD3) is an important member of the FOX family, which can maintain the pluripotent properties of cell clusters, neural crest, and trophoblastic progenitor cells in vivo. It has been shown that FOXD3 could affect proliferation, migration, and angiogenesis of various tumors and its deletion and overexpression in organisms will undoubtedly have important influence on the change of cell fate and the occurrence of tumors. However, the underlying functions and molecular mechanisms of FOXD3 in esophageal squamous cell carcinoma (ESCC) have not been fully clarified. According to the present study, the expression levels and functional roles of FOXD3 were investigated, and its prognostic value and molecular mechanisms in tumorigenesis and progression of ESCC were clarified. The expression level of FOXD3 was significantly downregulated in ESCC tissues and cell lines, and correlated with gender, family history of upper gastrointestinal cancer, TNM stage, depth of invasion, lymph node metastasis, and ESCC patients' survival. Moreover, FOXD3 inhibited cells migration and invasion as well as participated in TGF-β1 induced epithelial-mesenchymal transition process. Furthermore, a positive correlation between FOXD3 and SMAD family member 7 (SMAD7) was explored in ESCC. FOXD3 could directly bind to promoter regions of SMAD7 gene, leading to transcriptional promotion of SMAD7 in human esophageal cancer cells. Taken together, FOXD3 may play a tumor suppressor role in ESCC and may be applied as a new therapeutic target and prognostic marker for ESCC.

Identification of neuroblastoma cell lines with uncommon TAZ+/mesenchymal stromal cell phenotype with strong suppressive activity on natural killer cells

BackgroundNeuroblastoma (NB) is the most common, extracranial childhood solid tumor arising from neural crest progenitor cells and is a primary cause of death in pediatric patients. In solid tumors, stromal...

Abstract 17084: Nuclear Smooth Muscle α-actin Participates in Chromatin Remodeling at Smooth Muscle Contractile Gene Promoters

Actin genes encode for cytoskeletal proteins that polymerize to function in cellular motility, adhesion, and contraction. In mammalian cells, ubiquitously expressed β-actin also moves into the nucleus and associates with chromatin remodeling complexes, however a nuclear function of muscle-specific α-actins has not been previously assessed. We hypothesized that smooth muscle α-actin (SMA) plays a role in chromatin remodeling during the differentiation of smooth muscle cells (SMCs) to enable cell fate specification of SMCs. In explanted SMCs from human and mouse ascending aortas, cell fractionation and 2D gel electrophoresis identify both SMA and β-actin in the nuclear lysates. Nuclear SMA but not β-actin accumulates with SMC differentiation driven by serum starvation and transforming growth factor-β1 treatment. SMA accumulates into the nucleus early in the differentiation of SMCs from neural crest progenitor cells, prior to cytosolic accumulation. Immunoprecipitation studies show that SMA binds specifically to the INO80 and the SWI/SNF chromatin remodeling complexes, and this binding increases with SMC differentiation. Chromatin immunoprecipitation reveals that SMA is bound to the promoters of SMC-specific genes, including Acta2 , Cnn1, and Myh11 and that SMA is enriched over β-actin at these promoters with SMC differentiation. Finally, overexpression of SMA tagged with a nuclear localization sequence (NLS) in multiple cell types increases expression of SMC markers, whereas NLS-tagged β-actin localizes to the nucleus to the same extent but does not increase SMC marker expression in any cell type. Finally, we assessed whether skeletal muscle α-actin (SKA) and cardiac muscle α-actin (CMA) may play a similar role in skeletal and cardiac muscle cells. Both SKA and CMA translocate into the nucleus. CMA accumulates into the nucleus early in the differentiation of cardiomyocytes from pluripotent stem cells. Immunoprecipitation reveals that SKA binds to the SWI/SNF complex in differentiated C2C12 myotube cell cultures. These data support that nuclear SMA enriches with and participates in SMC differentiation, and suggest a potential nuclear role for other muscle specific α-actins in developing muscle cells.

Abstract B28: A cross-species enhancer activity analysis approach to identify the Ewing sarcoma cell of origin

Abstract Ewing sarcoma is a malignant bone and soft tissue tumor in children and adolescents. In 85% of all cases the formation of Ewing sarcoma is caused by a chromosomal translocation, leading to the expression of the oncogene EWS-FLI1. This aberrant transcription factor is the main driver of the disease and leads to massive transcriptional dysregulation. Although the genetic mechanism driving Ewing sarcoma is well understood, an animal model adequately mimicking the disease is still lacking. One reason why modeling attempts have remained difficult is the elusive cell of origin in Ewing sarcoma. Several cell types including neural crest progenitor cells and mesenchymal stem cells have been proposed, but none of them has yet been confirmed as cell of origin of Ewing sarcoma. Towards identifying this cell of origin, we are currently following a novel cross-species approach by exploring the use of enhancers, which are specifically active in Ewing sarcoma cells, but were not created de novo by EWS-FLI1. Injection of reporter constructs into zebrafish embryos allows for visualization of cell types with activity of the selected enhancers and provides us with cell-of-origin candidate cell types. To investigate which of these candidate cells are permissive for development of Ewing-like tumors, we will also express EWS-FLI1 in these cells. If successful, this approach will not only reveal the Ewing sarcoma cell of origin but also result in a zebrafish Ewing sarcoma model, which will help to understand tumor initiation and progression and, furthermore, will be a valuable tool to develop novel therapeutic strategies. Citation Format: Sarah Grissenberger, Anna Poetsch, Monika Heinzl, Luisa Morelli, Nathan Sheffield, Niko Popitsch, Heinrich Kovar, Martin Distel. A cross-species enhancer activity analysis approach to identify the Ewing sarcoma cell of origin [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr B28.

Head and Neck Paragangliomas: CT, MR, and 68Ga-DOTATATE PET Imaging

Paragangliomas are rare neuroendocrine tumors that result from the abnormal migration of neural crest progenitor cells, or paraganglia, during embryonic development. Paraganglia in the head and neck migrate along a branchial mesoderm; therefore, head and neck paragangliomas may occur anywhere along the branchiomeric distribution. Head and neck paragangliomas demonstrate a number of characteristic features, such as common anatomic locations, symptomatology, associated genetic mutations, and appearance on multimodal imaging. Understanding these important attributes can allow for a prompt and accurate diagnosis. This article provides a pictorial review of the common imaging features of head and neck paragangliomas.Learning Objective: Describe the multimodal imaging appearance of head and neck paragangliomas and their common anatomic locations.

Novel genetic loci affecting facial shape variation in humans.

The human face represents a combined set of highly heritable phenotypes, but knowledge on its genetic architecture remains limited, despite the relevance for various fields. A series of genome-wide association studies on 78 facial shape phenotypes quantified from 3-dimensional facial images of 10,115 Europeans identified 24 genetic loci reaching study-wide suggestive association (p < 5 × 10-8), among which 17 were previously unreported. A follow-up multi-ethnic study in additional 7917 individuals confirmed 10 loci including six unreported ones (padjusted < 2.1 × 10-3). A global map of derived polygenic face scores assembled facial features in major continental groups consistent with anthropological knowledge. Analyses of epigenomic datasets from cranial neural crest cells revealed abundant cis-regulatory activities at the face-associated genetic loci. Luciferase reporter assays in neural crest progenitor cells highlighted enhancer activities of several face-associated DNA variants. These results substantially advance our understanding of the genetic basis underlying human facial variation and provide candidates for future in-vivo functional studies.

BDNF and NT3 Reprogram Human Ectomesenchymal Dental Pulp Stem Cells to Neurogenic and Gliogenic Neural Crest Progenitors Cultured in Serum-Free Medium.

Human Dental Pulp Stem Cells (hDPSCs) are one of the most promising types of cells to regenerate nerve tissues. Standard DMEM+10% fetal bovine serum (FBS) culture medium allows a fast expansion of hDPSC as a surface-adherent cell monolayer. However, the use of FBS also compromises the clinical use of these protocols, and its longterm presence favors hDPSCs differentiation toward mesenchymal cell-derived lineages, at the expense of a reduced capability to generate neural cells. The objective of this work was to characterize the role of neurotrophin signaling on hDPSCs using a serum-free culture protocol, and to assess the neurogenic and gliogenic capacity of hDPSCs for future nerve tissue bioengineering and regeneration. We compared the different expression of neurotrophin receptors by RT-PCR, Q-PCR, and IF of hDPSCs cultured with different growth media in the presence or absence of serum. Moreover, we assessed the response of hDPSCs to stimulation of neurotransmitter receptors by live cell calcium imaging under these different media. Finally, we compared the osteogenic potential of hDPSCs by Alizarin red staining, and the differentiation to gliogenic/neurogenic fates by immunostaining for Schwann lineage and neuronal lineage markers. We tested a commercial serum-free medium designed for the growth of mesenchymal stem cells: StemPro MSCTM (STP). hDPSCs cultured in STP generated small non-adherent floating dentospheres that showed very low proliferation rates, in contrast to standard FBS-containing medium. We found that hDPSCs grown in STP conditions overexpressed neurotrophin receptor genes NTRK2 (TrkB) and NTRK3 (TrkC). Interestingly, the stimulation of these receptors by adding their respective ligands BDNF and NT-3 to STP medium enhanced the neural crest (NC) progenitor features of cultured hDPSCs. We observed a 10 to 100-fold increase of migratory NC cell markers HNK1 and P75NTR, and a significant overexpression of pluripotency core factors SOX2, OCT4 and NANOG. Moreover, hDPSCs cultured in BDNF/NT-3 supplemented STP showed a largely increased potential to differentiate towards neuronal and Schwann glial lineage cells, assessed by positive immunostaining for DCX, NeuN and S100ß, p75NTR markers, respectively. Our results demonstrate that the use of BDNF and NT-3 combined with STP induced the partial reprogramming of ectomesenchymal hDPSCs to generate early NC progenitor cells, which are far more competent for neuronal and glial differentiation than hDPSCs grown in the presence of FBS.

Expression of the Neuroblastoma-Associated ALK-F1174L Activating Mutation During Embryogenesis Impairs the Differentiation of Neural Crest Progenitors in Sympathetic Ganglia.

Neuroblastoma (NB) is an embryonal malignancy derived from the abnormal differentiation of the sympathetic nervous system. The Anaplastic Lymphoma Kinase (ALK) gene is frequently altered in NB, through copy number alterations and activating mutations, and represents a predisposition in NB-genesis when mutated. Our previously published data suggested that ALK activating mutations may impair the differentiation potential of neural crest (NC) progenitor cells. Here, we demonstrated that the expression of the endogenous ALK gene starts at E10.5 in the developing sympathetic ganglia (SG). To decipher the impact of deregulated ALK signaling during embryogenesis on the formation and differentiation of sympathetic neuroblasts, Sox10-Cre;LSL-ALK-F1174L embryos were produced to restrict the expression of the human ALK-F1174L transgene to migrating NC cells (NCCs). First, ALK-F1174L mediated an embryonic lethality at mid-gestation and an enlargement of SG with a disorganized architecture in Sox10-Cre;LSL-ALK-F1174L embryos at E10.5 and E11.5. Second, early sympathetic differentiation was severely impaired in Sox10-Cre;LSL-ALK-F1174L embryos. Indeed, their SG displayed a marked increase in the proportion of NCCs and a decrease of sympathetic neuroblasts at both embryonic stages. Third, neuronal and noradrenergic differentiations were blocked in Sox10-Cre;LSL-ALK-F1174L SG, as a reduced proportion of Phox2b+ sympathoblasts expressed βIII-tubulin and almost none were Tyrosine Hydroxylase (TH) positive. Finally, at E10.5, ALK-F1174L mediated an important increase in the proliferation of Phox2b+ progenitors, affecting the transient cell cycle exit observed in normal SG at this embryonic stage. Altogether, we report for the first time that the expression of the human ALK-F1174L mutation in NCCs during embryonic development profoundly disturbs early sympathetic progenitor differentiation, in addition to increasing their proliferation, both mechanisms being potential crucial events in NB oncogenesis.

Derivation of enteric neuron lineages from human pluripotent stem cells.

The enteric nervous system (ENS) represents a vast network of neuronal and glial cell types that develops entirely from migratory neural crest (NC) progenitor cells. Considerable improvements in the understanding of the molecular mechanisms underlying NC induction and regional specification have recently led to the development of a robust method to re-create the process in vitro using human pluripotent stem cells (hPSCs). Directing the fate of hPSCs toward the enteric NC (ENC) results in an accessible and scalable in vitro model of ENS development. The application of hPSC-derived enteric neural lineages provides a powerful platform for ENS-related disease modeling and drug discovery. Here we present a detailed protocol for the induction of a regionally specific NC intermediate that occurs over the course of a 15-d interval and is an effective source for the in vitro derivation of functional enteric neurons (ENs) from hPSCs. Additionally, we introduce a new and improved protocol that we have developed to optimize the protocol for future applications in regenerative medicine, in which components of undefined activity have been replaced with fully defined culture conditions. This protocol provides access to a broad range of human ENS lineages within a 30-d period.

Maintaining multipotent trunk neural crest stem cells as self-renewing crestospheres

Neural crest cells have broad migratory and differentiative ability that differs according to their axial level of origin. However, their transient nature has limited understanding of their stem cell and self-renewal properties. While an in vitro culture method has made it possible to maintain cranial neural crest cells as self-renewing multipotent crestospheres (Kerosuo et al., 2015), these same conditions failed to preserve trunk neural crest in a stem-like state. Here we optimize culture conditions for maintenance of avian trunk crestospheres, comprised of both neural crest stem and progenitor cells. Our trunk-derived crestospheres are multipotent and display self-renewal capacity over several weeks. Trunk crestospheres display elevated expression of neural crest cell markers as compared to those characteristic of ventrolateral neural tube or mesodermal fates. Moreover, trunk crestospheres express increased levels of trunk neural crest-enriched markers as compared to cranial crestospheres. Finally, we use lentiviral transduction as a tool to manipulate gene expression in trunk crestospheres. Taken together, this method enables long-term in vitro maintenance and manipulation of multipotent trunk neural crest cells in a premigratory stem or early progenitor state. Trunk crestospheres are a valuable resource for probing mechanisms underlying neural crest stemness and lineage decisions as well as accompanying diseases.

TFII-I and AP2α Co-Occupy the Promoters of Key Regulatory Genes Associated with Craniofacial Development.

The aim of this study is to define the candidate target genes for TFII-I and AP2α regulation in neural crest progenitor cells. The GTF2I and GTF2IRD1 genes encoding the TFII-I family of transcription factors are prime candidates for the Williams-Beuren syndrome, a complex multisystem disorder characterized by craniofacial, skeletal, and neurocognitive deficiencies. AP2α, a product of the TFAP2A gene, is a master regulator of neural crest cell lineage. Mutations in TFAP2A cause branchio-oculo-facial syndrome characterized by dysmorphic facial features and orofacial clefts. In this study, we examined the genome-wide promoter occupancy of TFII-I and AP2α in neural crest progenitor cells derived from in vitro-differentiated human embryonic stem cells. Our study revealed that TFII-I and AP2α co-occupy a selective set of genes that control the specification of neural crest cells. The data suggest that TFII-I and AP2α may coordinately control the expression of genes encoding chromatin-modifying proteins, epigenetic enzymes, transcription factors, and signaling proteins.

MYCN drives glutaminolysis in neuroblastoma and confers sensitivity to an ROS augmenting agent

Heightened aerobic glycolysis and glutaminolysis are characteristic metabolic phenotypes in cancer cells. Neuroblastoma (NBL), a devastating pediatric cancer, is featured by frequent genomic amplification of MYCN, a member of the Myc oncogene family that is primarily expressed in the early stage of embryonic development and required for neural crest development. Here we report that an enriched glutaminolysis gene signature is associated with MYCN amplification in children with NBL. The partial knockdown of MYCN suppresses glutaminolysis in NBL cells. Conversely, forced overexpression of MYCN in neural crest progenitor cells enhances glutaminolysis. Importantly, glutaminolysis induces oxidative stress by producing reactive oxygen species (ROS), rendering NBL cells sensitive to ROS augmentation. Through a small-scale metabolic-modulator screening, we have found that dimethyl fumarate (DMF), a Food and Drug Administration-approved drug for multiple sclerosis, suppresses NBL cell proliferation in vitro and tumor growth in vivo. DMF suppresses NBL cell proliferation through inducing ROS and subsequently suppressing MYCN expression, which is rescued by an ROS scavenger. Our findings suggest that the metabolic modulation and ROS augmentation could be used as novel strategies in treating NBL and other MYC-driven cancers.

In Vitro Maintenance of Multipotent Neural Crest Stem Cells as Crestospheres.

Neural crest cells are a critical source of many cell types of the vertebrate body. However, as a stem cell population they are peculiar because of the transient nature of their stem cell niche; soon after the multipotent neural crest cells are specified in the neuroepithelium, they become mesenchymal cells that migrate into various destinations in early embryos. These rapid in vivo changes during neural crest development complicate the studies on their stem cell properties. Crestospheres are in vitro maintained primary cultures of premigratory neural crest cells that maintain a mixture of neural crest stem and progenitor cells for weeks without spontaneous differentiation, including the multipotent neural crest stem cells. Here, we describe how crestosphere cultures are initiated from either cranial or trunk levels of chick embryos. Alternatively, the same culture conditions can be used to maintain human embryonic stem cell-derived neural crest cells as crestospheres. Thus, crestospheres provide a useful tool for studies on neural crest stemness.

Novel Genetic Loci Affecting Facial Shape Variation in Humans

The human face represents a combined set of highly heritable phenotypes, but knowledge on its genetic architecture remains limited. A series of genome-wide association studies on 78 facial shape phenotypes quantified from 3-dimensional facial images of 10,115 Europeans identified 24 genetic loci, among which 17 were previously unpublished. A multi-ethnic replication study in 7,917 individuals confirmed 13 loci including 8 unpublished ones. Allele frequencies at the face-associated loci were significantly more differentiated among populations than genome background, supporting a role of nature selection in shaping genetic differentiation underlying facial variation. Analyses of epigenomic datasets from cranial neural crest cells revealed abundant cis-regulatory activities at the face-associated loci. Luciferase reporter assays in neural crest progenitor cells highlighted enhancer activities at INTU, PAX3, RPGRIP1L. Knocking-out two face-associated genes TBX15 and PAX1 in mice resulted in craniofacial dysmorphology. These results substantially advance our understanding of the genetic and functional basis of human facial variation.

Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare and highly aggressive carcinoma of the skin with a high recurrence rate and propensity for metastasis. It was first described in 1972 and subsequently reclassified as a neuroendocrine tumor. Merkel cells are now thought to arise from the epidermal stem cells, not neural crest progenitor cells, as originally thought, and are the only cutaneous cells that form electron-dense neurosecretory granules. Although rare, the incidence of MCC is rapidly increasing. MCC is more often than not associated with Merkel cell polyomavirus, which may be involved in the malignant transformation and pathogenesis of MCC. Mortality exceeds that of the more commonly occurring skin cancer melanoma, with an overall 5-year survival rate ranging from 30 to 64%. Large reviews have documented recurrence rates ranging from 25 to 50% for local recurrence, 52 to 59% for regional recurrence, and 34 to 36% for distant metastases. Early-stage disease can sometimes be cured with surgery and radiation. Due to the rarity of MCC, statistically significant prospective data are lacking to validate prognostic features and treatment. Therefore, recommendations are largely based on small studies, meta-analyses, and expert consensus. Moreover, no consistent molecular activator in MCC has been identified, resulting in large variability in targeted therapies used in its treatment. New therapies to treat advanced MCC, including immunotherapy, hold promise for improved outcomes in the future. This review summarizes current knowledge regarding the etiology, prognosis, and management of MCC. This review contains 6 figures, 4 tables and 52 references Key words: Merkel cell carcinoma, Merkel cell polyomavirus, Merkel cell tactile receptor

Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare and highly aggressive carcinoma of the skin with a high recurrence rate and propensity for metastasis. It was first described in 1972 and subsequently reclassified as a neuroendocrine tumor. Merkel cells are now thought to arise from the epidermal stem cells, not neural crest progenitor cells, as originally thought, and are the only cutaneous cells that form electron-dense neurosecretory granules. Although rare, the incidence of MCC is rapidly increasing. MCC is more often than not associated with Merkel cell polyomavirus, which may be involved in the malignant transformation and pathogenesis of MCC. Mortality exceeds that of the more commonly occurring skin cancer melanoma, with an overall 5-year survival rate ranging from 30 to 64%. Large reviews have documented recurrence rates ranging from 25 to 50% for local recurrence, 52 to 59% for regional recurrence, and 34 to 36% for distant metastases. Early-stage disease can sometimes be cured with surgery and radiation. Due to the rarity of MCC, statistically significant prospective data are lacking to validate prognostic features and treatment. Therefore, recommendations are largely based on small studies, meta-analyses, and expert consensus. Moreover, no consistent molecular activator in MCC has been identified, resulting in large variability in targeted therapies used in its treatment. New therapies to treat advanced MCC, including immunotherapy, hold promise for improved outcomes in the future. This review summarizes current knowledge regarding the etiology, prognosis, and management of MCC. This review contains 6 figures, 4 tables and 52 references Key words: Merkel cell carcinoma, Merkel cell polyomavirus, Merkel cell tactile receptor