Human melanoma samples comparing nevi and primary and metastatic melanoma
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ABSTRACT:
ORGANISM(S): Homo sapiens
SUBMITTER: Kwong Lawrence
PROVIDER: S-ECPF-GEOD-46517 | biostudies-other |
REPOSITORIES: biostudies-other
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Project description:We sought to identify genes and gene signatures which correlate with progression by sampling human melanomas from nevi, primary, and metastatic tumors. The large number of samples also permits analysis within groups.
2013-05-01 | GSE46517 | GEO
Project description:We sought to identify genes and gene signatures which correlate with progression by sampling human melanomas from nevi, primary, and metastatic tumors. The large number of samples also permits analysis within groups. Human melanoma samples were isolated from historical frozen patient specimens. RNA was extracted and run on the human Affymetrix U133A microarray chip.
2013-05-01 | E-GEOD-46517 | biostudies-arrayexpress
Project description:Genetic susceptibility to nevi may affect the risk of developing melanoma, since common and atypical nevi are the main host risk factors implicated in the development of cutaneous melanoma. Recent genome-wide studies defined a melanoma polygenic risk score based on variants in genes involved in different pathways, including nevogenesis. Moreover, a predisposition to nevi is a hereditary trait that may account for melanoma clustering in some families characterized by cases with a high nevi density. On the other hand, familial melanoma aggregation may be due to a Mendelian inheritance of high/moderate-penetrance pathogenic variants affecting melanoma risk, regardless of the nevus count. Based on current knowledge, this review analyzes the complex interplay between nevi and melanoma predisposition in a familial context. We review familial melanoma, starting from Whiteman's divergent pathway model to overall melanoma development, distinguishing between nevi-related (cases with a high nevus count and a high polygenic risk score) and nevi-resistant (high/moderate-penetrance variant-carrier cases) familial melanoma. This distinction could better direct future research on genetic factors useful to identify high-risk subjects.
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Project description:PurposeTo evaluate the protein expression characteristics of genes employed in a recently introduced prognostic gene expression assay for patients with cutaneous melanoma (CM).MethodsWe studied 37 patients with CM and 10 with benign (melanocytic) nevi (BN). Immunohistochemistry of primary tumor tissue was performed for eight proteins: COL6A6, DCD, GBP4, KLHL41, KRT9, PIP, SCGB1D2, SCGB2A2.ResultsThe protein expression of most markers investigated was relatively low (e.g., DCD, KRT9, SCGB1D2) and predominantly cytoplasmatic in melanocytes and keratinocytes. COL6A6, GBP4, and KLHL41 expression was significantly enhanced in CM when compared to BN. DCD protein expression was significantly correlated with COL6A6, GBP4, and KLHL41. GBP4 was positively correlated with KLHL41 and inversely correlated with SCGB2B2. The latter was also inversely correlated with serum S100B levels at time of initial diagnosis. The presence of SCGB1D2 expression was significantly associated with ulceration of the primary tumor. KRT9 protein expression was significantly more likely found in acral lentiginous melanoma. The presence of DCD expression was less likely associated with superficial spreading melanoma subtype but significantly associated with non-progressive disease. The absence of SCGB2A2 expression was significantly more often observed in patients who did not progress to stage III or IV.ConclusionsThe expression levels observed were relatively low but differed in part with those found in BN. Even though we detected some significant correlations between the protein expression levels and clinical parameters (e.g., CM subtype, course of disease), there was no major concordance with the protective or risk-associated functions of the corresponding genes included in a recently introduced prognostic gene expression assay.
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Project description:Cutaneous melanoma is an increasingly common form of skin cancer. The molecular mechanisms regulating melanoma progression are not completely understood. We speculated that specific miRNAs may be involved in melanoma development. We compared the miRNA expression profiles of benign nevi and metastatic melanomas. Unsupervised hierarchical clustering demonstrated a distinct miRNA expression pattern in metastatic melanomas compared to nevi. We identified miRNAs that were differentially expressed in melanoma. Notably, miR-193b was significantly down-regulated in the melanoma tissue examined. Using functional studies we demonstrated that over-expression of miR-193b significantly reduced melanoma cell proliferation, and arrested cell at G1 phase. Further gene expression analysis revealed that miR-193b regulated targets involved in cell cycle. Cyclin D1 was down-regulated by miR-193b at both the mRNA and protein level. This is the first study to show that the miR-193b may reduce cell proliferation by directly repressing cyclin D1. Overall, our study suggests that miRNAs are dysregulated in metastatic melanoma, and that miR-193b may play an important role in melanoma. 8 benign nevi and 8 metastatic melanoma tissue samples were profiled by Agilent MicroRNA Microarray (V1.5).
| S-ECPF-GEOD-18509 | biostudies-other
Project description:According to the prevailing multistep model of melanoma development, oncogenic BRAF or NRAS mutations are crucial initial events in melanoma development. It is not known whether melanocytic nevi that are found in association with a melanoma are more likely to carry BRAF or NRAS mutations than uninvolved nevi. By laser microdissection we were able to selectively dissect and genotype cells either from the nevus or from the melanoma part of 46 melanomas that developed in association with a nevus. In 25 cases we also genotyped a control nevus of the same patients. Available tissue was also immunostained using the BRAF(V600E)-mutation specific antibody VE1. The BRAF(V600E) mutation was found in 63.0% of melanomas, 65.2% of associated nevi and 50.0% of control nevi. No significant differences in the distribution of BRAF or NRAS mutations could be found between melanoma and associated nevi or between melanoma associated nevi and control nevi. In concordant cases immunohistochemistry showed a higher expression (intensity of immunohistochemistry) of the mutated BRAF(V600E)-protein in melanomas compared to their associated nevi. In this series the presence of a BRAF- or NRAS mutation in a nevus was not associated with the risk of malignant transformation. Our findings do not support the current traditional model of stepwise tumor progression.
| S-EPMC3704624 | biostudies-literature
Project description:Despite malignant cutaneous melanoma is relatively rare compared to other skin cancers, it is still responsible for 80% of all skin cancer-related deaths. To identify molecular signatures of melanoma progression, excisional biopsies from 18 common melanocytic nevi (CMN), 8 primary radial growth phase melanomas (RGPM), 15 primary vertical growth phase melanomas (VGPM) and 5 melanoma metastases (MTS) were profiled using whole genome oligo-microarrays. Differentially expressed genes for each progression step were identified, and validation of selected transcripts by qRT-PCR was performed on an independent cohort of fixed samples. The comparison between CMN and RGPM showed an enrichment of Gene Ontology (GO) terms related to inter and intra-cellular junctions, whereas the transition from RGPM to VGPM was characterized by the deregulation of WNT3, MAPK and AKT pathways. In this step, enrichment analysis underlined the alteration of biological processes linked to apoptosis. Upregulation of genes involved into DNA double-strand breaks repair and downregulation of cellular adhesion genes were observed in MTS respect to VGPM. Futhermore, the gene expression profiles of 11 dysplastic nevi (DN) were compared to all the others. Some genes controlling proliferation were found more expressed than in CMN. Overall, DN displayed an heterogeneous behaviour, with relevant oncogenes, such as MYC and BCL6, less expressed than in RGPM, and a modulation pattern similar to VGPM for a subset of gene families, such as mismatch repair. This suggests that DN is not an intermediate step within melanoma progression, but a separate entity with an independent risk of progression to melanoma Experiment Overall Design: In order to identify genes implicated during the course of melanoma development and progression, a total of 57 excisional biopsies from common melanocytic nevi (n = 18), dysplastic nevi (n = 11), primary radial growth phase malignant melanomas (n = 8), primary vertical growth phase malignant melanomas (n = 15) and melanoma metastases (n = 5) were analyzed. Total RNA was isolated by using RNeasy Mini Kit (Qiagen, Dusseldorf, Germany). TotRNA quality was checked by means of RNA 6000 pico chip assays (Agilent Technologies, Palo Alto, CA) run on the Agilent 2100 bioanalyzer. RNA isolated from each fresh tissue and from the human universal reference (BD™ Human Universal Reference Total RNA, Clontech, Palo Alto, CA) was amplified by means of the Amino Allyl MessageAmp II aRNA Kit (Ambion) to obtain amino allyl antisense RNA (aaRNA) following the method developed by Eberwine and coworkers. Two rounds of amplification were performed to obtain the necessary quantity of aaRNA for labeling. Briefly: mRNA was reverse transcribed in cDNA single strand; after the second strand synthesis (in the second round of amplification), cDNA was in vitro transcribed in aaRNA including amino allyl modified nucleotides (aaUTP). Both dsDNA and aaRNA underwent a purification step using columns provided with the kit. Labeling was performed using NHS ester Cy3 or Cy5 dyes (Amersham Biosciences, Buckinghamshire UK) able to react with the modified RNA. mRNA quality was checked by means of RNA 6000 nano chip assays (Agilent Technologies). At least 5 ug of mRNA for each sample were labeled and purified with columns. Equal amounts (0.75 ug) of labeled specimens from sample and reference were put together, fragmented and hybridized to oligonucleotide glass arrays representing 41K human unique genes and transcripts (Human Whole Genome Oligo Microarray Array, Agilent Technologies). All steps were performed using the In Situ Hybridization kit-plus (Agilent Technologies) and following the 60-mer oligo microarray processing protocol (Agilent Technologies). Then, slides were washed with the SSPE wash procedure and scanned with the dual-laser microarray scanner Agilent G2505B. For each sample, a dye-swap replicate was performed. To visually inspect the relationships among samples, unsupervised clustering analysis was applied to the ratios between each DN, RGPM , VGPM or MTS sample and the average profile of all the CMN included into the study, just selecting transcripts with p-value less than 0.01 in at least half of the samples considered. Transcripts modulated in each progression step were then selected by applying a cut-off of 2 for the B value yielded by the limma procedure applied on original ratios (sample over common reference). Initially, DN were included into either the CMN class or the RGPM one, according to the degree of their cyto-architectural atypia However, the presence of such lesions among either CMN or RGPM made the distinction between these two classes and between RGPM and VGPM much less clear. Therefore, to prevent the increasing of heterogeneity, DN were excluded and this allowed the detection of many more differentially expressed transcripts between CMN and RGPM and, especially, between RGPM and VGPM. The great difference found between metastases and the rest of the samples was consistent with unsupervised results. Enrichment of Gene Ontology categories (in particular, biological processes) and gene networks or cellular pathways was performed on each list by using DAVID functional annotation tool and applying a cut-off of 0.01 on the enrichment score obtained. For each progression step, some genes previously described as differentially expressed were found. Furthermore, other novel gene transcripts, never reported as involved in melanoma progression, were identified. The expression deregulation of some of these novel genes was then confirmed on an independent cohort of samples by RT-qPCR.
| S-ECPF-GEOD-12391 | biostudies-other
Project description:Cutaneous melanoma is an increasingly common form of skin cancer. The molecular mechanisms regulating melanoma progression are not completely understood. We speculated that specific miRNAs may be involved in melanoma development. We compared the miRNA expression profiles of benign nevi and metastatic melanomas. Unsupervised hierarchical clustering demonstrated a distinct miRNA expression pattern in metastatic melanomas compared to nevi. We identified miRNAs that were differentially expressed in melanoma. Notably, miR-193b was significantly down-regulated in the melanoma tissue examined. Using functional studies we demonstrated that over-expression of miR-193b significantly reduced melanoma cell proliferation, and arrested cell at G1 phase. Further gene expression analysis revealed that miR-193b regulated targets involved in cell cycle. Cyclin D1 was down-regulated by miR-193b at both the mRNA and protein level. This is the first study to show that the miR-193b may reduce cell proliferation by directly repressing cyclin D1. Overall, our study suggests that miRNAs are dysregulated in metastatic melanoma, and that miR-193b may play an important role in melanoma.
2009-12-20 | GSE18509 | GEO
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Project description: Not available
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