Characterization of the Merkel cell carcinoma miRNome
ABSTRACT: MicroRNAs have been implicated in various skin cancers, including melanoma, squamous cell carcinoma, and basal cell carcinoma; however, the expression of microRNAs and their role in Merkel cell carcinoma (MCC) have yet to be explored in depth. To identify microRNAs specific to MCC (MCC-miRs), next-generation sequencing (NGS) of small RNA libraries was performed on different tissue samples including MCCs, other cutaneous tumors, and normal skin. Comparison of the profiles identified several microRNAs upregulated and downregulated in MCC. For validation, their expression was measured via qRT-PCR in a larger group of MCC and in a comparison group of non-MCC cutaneous tumors and normal skin. Eight microRNAs were upregulated in MCC: miR-502-3p, miR-9, miR-7, miR-340, miR-182, miR-190b, miR-873, and miR-183. Three microRNAs were downregulated: miR-3170, miR-125b, and miR-374c. Many of these MCC-miRs, with the miR-183/182/96a cistron in particular, have connections to tumorigenic pathways implicated in MCC pathogenesis. In situ hybridization confirmed that the highly expressed MCC-miR, miR-182, is localized within tumor cells. Furthermore, NGS and qRT-PCR reveals that several of these MCC-miRs are highly expressed in the patient-derived MCC cell line, MS-1. These data indicate that we have identified a set of MCC-miRs with high implications for MCC research. To identify microRNAs specific to Merkel cell carcinoma (MCC) next-generation sequencing (NGS) of small RNA libraries was performed on different tissue samples including MCCs, other cutaneous tumors, and normal skin
Project description:Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine tumor with high mortality rates. Merkel cell polyomavirus (MCPyV), identified in the majority of MCC, may drive tumorigenesis via viral T antigens. However, mechanisms underlying pathogenesis in MCPyV-negative MCC remain poorly understood. To nominate genes contributing to pathogenesis of MCPyV-negative MCC, we performed DNA microarray analysis on 30 MCCs. MCPyV status of MCCs was determined by PCR for viral DNA and RNA. 1593 probe-sets were differentially expressed between MCPyV-negative and -positive MCC, with significant differential expression defined as at least 2-fold change in either direction and p-value of ≤ 0.05. MCPyV-negative tumors showed decreased RB1 expression, whereas MCPyV-positive tumors were enriched for immune response genes. Validation studies included immunohistochemistry demonstration of decreased RB protein expression in MCPyV-negative tumors and increased peritumoral CD8+ T lymphocytes surrounding MCPyV-positive tumors. In conclusion, our data suggest that loss of RB1 expression may play an important role in tumorigenesis of MCPyV-negative MCC. Functional and clinical validation studies are needed to determine whether this tumor suppressor pathway represents an avenue for targeted therapy. We used microarrays to characterize global gene expression patterns related to Merkel cell polyomavirus status in Merkel cell carcinoma. Furthermore, we compared Merkel cell carcinoma to less aggressive primary cutaneous carcinomas. We utilized flash-frozen tumor tissue from primary Merkel cell carcinomas, metastatic Merkel cell carcinomas, primary cutaneous squamous cell carcinomas, and basal cell carcinomas. Merkel cell carcinoma cell lines, which represent a pure population of tumor cells, were also included. Merkel cell polyomavirus status was determined at the DNA and RNA level using multiple primers for viral T-antigen and capsid protein sequences. This Series represents two analyses - one with new Samples normalized together, and another with some of the new Samples re-normalized with Samples previously submitted under Series GSE13355. The latter group contain 'renormalized' in the titles.
Project description:miRNAs are excellent tumor biomarkers because of their cell-type specificity and abundance. However, many miRNA detection methods, such as real-time (RT)-PCR, obliterate valuable visuospatial information in tissue samples. To enable miRNA visualization in formalin-fixed paraffin-embedded (FFPE) tissues, we developed multicolor miRNA fluorescence in situ hybridization (FISH). For proof-of-concept, we differentiated two skin tumors, namely Basal cell carcinoma (BCC) and Merkel cell carcinoma (MCC), with overlapping histologic features but distinct cellular origins. Using sequencing-based miRNA profiling and discriminant analysis, we identified tumor-specific miRNAs (miR-205 and miR-375) in BCC and MCC respectively. We addressed three major shortcomings in miRNA FISH, identifying optimal conditions for miRNA fixation and rRNA retention using model compounds and HPLC analyses, enhancing signal amplification and detection by increasing probe-hapten linker lengths, and improving probe specificity using shortened probes with minimal rRNA sequence complementarity. We validated our method on 4 BCC and 12 MCC tumors. Amplified miR-205 and miR-375 signals were normalized against directly detectable reference rRNA signals. Tumors were classified using pre-defined cut-off values; all were correctly identified in blinded analysis. We established a reliable miRNA FISH technique for parallel visualization of differentially expressed miRNAs in FFPE tumor tissues 6 MCC samples 2 normal skin samples were profiled with Agilent miRNA array platform
Project description:Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine tumor of the skin with growing incidence. In research immortalized cell lines are used for in vitro experiments in order to better understand the biology of this malignant disease.
Project description:Merkel cell carcinoma (MCC) is a polyomavirus-associated skin cancer that is frequently lethal and lacks established prognostic biomarkers. The purpose of this study was to use gene expression analysis to identify biomarkers that may improve prognostic accuracy and provide insight into MCC biology. Overall design: We profiled 35 tumors from 34 patients. Tumors were macrodissected from surrounding stroma. RNA isolation was performed with RNeasy or Allprep Mini kits (Qiagen, Alameda, CA), and RNA quality assessed by Agilent Bioanalyzer analysis. RNAs were profiled on the Human Rosetta Custom Affymetrix 2.0 chip.
Project description:Merkel cell carcinoma is a skin cancer associated with the Merkel cell polyomavirus (MCPyV) which is found integrated in the genome of the tumor cells. Here 4 MCPyV-positive tumor cell lines (AlDo, LoKe, BroLi and WoWe) were analyzed by comparative gernomic hybridization to define further genetic alterations. Corresponding peripheral blood lymphocytes (PBL) in case of AlDo and LoKe, purified T cells in case of BroLi and Tumor-derived but virus-negative cells of unknown origin (WoWe1) in case of WoWe served as controls. Overall design: Comparative genomic hybridization to define amplifications and deletions in the MCC genome.
Project description:Merkel cell carcinoma (MCC) is a polyomavirus-associated skin cancer that is frequently lethal and lacks established prognostic biomarkers. The purpose of this study was to use gene expression analysis to identify biomarkers that may improve prognostic accuracy and provide insight into MCC biology. We profiled 35 tumors from 34 patients. Tumors were macrodissected from surrounding stroma. RNA isolation was performed with RNeasy or Allprep Mini kits (Qiagen, Alameda, CA), and RNA quality assessed by Agilent Bioanalyzer analysis. RNAs were profiled on the Human Rosetta Custom Affymetrix 2.0 chip.
Project description:Merkel cell carcinoma (MCC) is a highly aggressive, neuroendocrine skin cancer that lacks actionable mutations, which could be utilized for targeted therapies. Epigenetic regulators governing cell identity may represent unexplored therapeutic entry points. Here, we targeted epigenetic regulators in a pharmacological screen and discovered that the lysine-specific histone demethylase 1A (LSD1/KDM1A) is required for MCC growth in vitro and in vivo. We show that LSD1 inhibition in MCC disrupts the LSD1-CoREST complex leading to displacement and degradation of HMG20B (BRAF35), a poorly characterized complex member that is essential for MCC proliferation. Inhibition of LSD1 causes derepression of transcriptional master regulators of the neuronal lineage, activates a gene expression signature resembling normal Merkel cells, and induces cell cycle arrest and cell death. Our study unveils the importance of LSD1 for proliferation and maintaining cell identity in MCC. There is growing evidence that cancer cells exploit cellular plasticity and dedifferentiation programs to evade destruction by the immune system. The combination of LSD1 inhibitors with checkpoint inhibitors may thus represent a promising treatment strategy for MCC patients.
Project description:Merkel cell polyomavirus (MCPyV) is an etiological agent of Merkel cell carcinoma (MCC), a highly aggressive skin cancer. The MCPyV small tumor antigen (ST) is required for maintenance of MCC and can transform normal cells. To gain insight into cellular perturbations induced by MCPyV ST, we performed transcriptome analysis of normal human fibroblasts with inducible expression of ST. MCPyV ST dynamically alters the cellular transcriptome with increased levels of glycolytic genes, including the monocarboxylate lactate transporter SLC16A1 (MCT1). Extracellular flux analysis revealed increased lactate export reflecting elevated aerobic glycolysis in ST expressing cells. Inhibition of MCT1 activity suppressed the growth of MCC cell lines and impaired MCPyV-dependent transformation of IMR90 cells. Both NF-κB and MYC have been shown to regulate MCT1 expression. While MYC was required for MCT1 induction, MCPyV-induced MCT1 levels decreased following knockdown of the NF-κB subunit RelA, supporting a synergistic activity between MCPyV and MYC in regulating MCT1 levels. Several MCC lines had high levels of MYCL and MYCN but not MYC. Increased levels of MYCL was more effective than MYC or MYCN in increasing extracellular acidification in MCC cells. Our results demonstrate the effects of MCPyV ST on the cellular transcriptome and reveal that transformation is dependent, at least in part, on elevated aerobic glycolysis. Overall design: Expression of MCPyV ST or GFP was induced in IMR90 fibroblasts, and triplicate RNA samples were extracted and sequenced every 8 hours for a total of 96 hours
Project description:We performed miRNA expression profiling in a series of human Merkel Cell carcinoma samples using a microarray approach. Significant differentially expressed miRNAs among groups were identified using SAM analysis. Agilent microarray platform containing 723 human miRNAs was used to determine miRNA expression profiles in 16 human Merkel cell carcinoma (MCC) samples. To validate the microarray platform, the expression levels of selected miRNAs were evaluated using qRT-PCR.
Project description:MicroRNAs (miRs) have been recognized as promising biomarkers. It is unknown to what extent tumor-derived miRs are differentially expressed between primary colorectal cancers (pCRCs) and metastatic lesions, and to what extent the expression profiles of tumor tissue differ from the surrounding normal tissue. Next-generation sequencing (NGS) of 220 fresh-frozen samples, including paired primary and metastatic tumor tissue and non-tumorous tissue from 38 patients, revealed expression of 2245 known unique mature miRs and 515 novel candidate miRs. Unsupervised clustering of miR expression profiles of pCRC tissue with paired metastases did not separate the two entities, whereas unsupervised clustering of miR expression profiles of pCRC with normal colorectal mucosa demonstrated complete separation of the tumor samples from their paired normal mucosa. Two hundred and twenty-two miRs differentiated both pCRC and metastases from normal tissue samples (false discovery rate (FDR) <0.05). The highest expressed tumor-specific miRs were miR-21 and miR-92a, both previously described to be involved in CRC with potential as circulating biomarker for early detection. Only eight miRs, 0.5% of the analysed miR transcriptome, were differentially expressed between pCRC and the corresponding metastases (FDR <0.1), consisting of five known miRs (miR-320b, miR-320d, miR-3117, miR-1246 and miR-663b) and three novel candidate miRs (chr 1-2552-5p, chr 8-20656-5p and chr 10-25333-3p). These results indicate that previously unrecognized candidate miRs expressed in advanced CRC were identified using NGS. In addition, miR expression profiles of pCRC and metastatic lesions are highly comparable and may be of similar predictive value for prognosis or response to treatment in patients with advanced CRC.