Single cell RNA-seq profiling of patient-derived Merkel cell carcinoma tumor samples
Ontology highlight
ABSTRACT: Merkel cell carcinoma (MCC), a rare but aggressive neuroendocrine cancer of the skin, remains a challenge in the era of precision medicine. MCC tumor heterogeneity has been attributed to the variant disease etiologies, mediated by either UV exposure or Merkel cell polyomavirus (MCPyV). However, over the years it has become clear that these two groups are largely similar in clinical presentation, prognosis, and treatment response to immune-checkpoint inhibitors. We therefore dissected the transcriptomic heterogeneity of a panel of patient tumors samples, at the single-cell resolution, to gather further insights.
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: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.
Project description:Merkel cells are epidermal mechanoreceptor cells responsible for the perception of gentle touch. Merkel cell carcinoma (MCC) is a rare and highly aggressive skin cancer. Although MCC histologically resembles Merkel cells, the cell of origin for MCC is unknown. MCC frequently contains integrated Merkel cell polyomavirus (MCPyV), a small DNA tumor virus with widespread prevalence. Whether MCPyV can transform Merkel cells is unknown. Here, we describe the isolation and long-term expansion of human Merkel cells from neonatal foreskin. We validated the expression of several Merkel cell-related factors by RNASeq, and assessed the ultrastructure by electron microscopy. Culture of Merkel cell preparations on an artificial basement membrane promoted the formation of structures containing both Merkel and non-Merkel cell populations. To determine whether Merkel cells were susceptible to transformation, we expressed tumor-derived MCPyV T antigens and additional oncogenes. We were unable to demonstrate tumorigenesis in immunodeficient mice, but were able to detect T antigen expression from excised cells weeks after implantation. These results highlight that foreskin-isolated Merkel cells can be propagated extensively, sustain expression of MCPyV T antigens, but are not susceptible to transformation by MCPyV, suggesting that Merkel cells from non-glabrous skin may not be a cell of origin for MCC.
Project description:Merkel cell polyomavirus (MCPyV) is linked to Merkel cell carcinoma (MCC), a rare and aggressive skin cancer. This study investigated the influence of MCPyV T antigens on the host genome using transcriptomics and epigenomics. Results revealed a role for the small Tumor (sT) antigen in subverting type I interferon response and immune evasion, contributing to persistent infection and tumor progression. These findings enhance our understanding of MCPyV pathogenesis and may inform new therapeutic strategies.
Project description:Merkel cell polyomavirus (MCPyV) is linked to Merkel cell carcinoma (MCC), a rare and aggressive skin cancer. This study investigated the influence of MCPyV T antigens on the host genome using transcriptomics and epigenomics. Results revealed a role for the small Tumor (sT) antigen in subverting type I interferon response and immune evasion, contributing to persistent infection and tumor progression. These findings enhance our understanding of MCPyV pathogenesis and may inform new therapeutic strategies.
Project description:Merkel cell polyomavirus (MCPyV) is the first human polyomavirus etiologically associated with Merkel cell carcinoma (MCC), a rare and aggressive form of skin cancer. Similar to other polyomaviruses, MCPyV encodes early T antigen genes, a viral oncogene required for MCC tumor growth. To identify the unique oncogenic properties of MCPyV, we analysed the gene expression profiles in human spontaneously immortalized keratinocytes (NIKs) expressing the early genes from five distinct human polyomaviruses (PyVs), including MCPyV. A comparison of the gene expression profiles revealed 28 genes specifically deregulated by MCPyV.
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.
Project description:Merkel cell carcinoma is supposed to be derived from Merkel cells after infection by Merkel cell polyomavirus (MCPyV) and other poorly known events. A transcriptional profiling with cDNA microarrays was performed on cells from MCPyV(+) Merkel cell carcinomas and isolated normal Merkel cells. This microarray revealed numerous significantly upregulated genes and downregulated genes. The extensive list of genes identified in these experiments provides a large body of potentially valuable information of Merkel cell carcinoma carcinogenesis and could represent a source of potential targets for cancer therapy.
Project description:Co-expression of MCPyV TAgs and the Merkel cell lineage determinant ATOH1, in p53-deficient keratinocytes and their neuroendocrine progeny, yields tumors closely mimicking human MCC. Direct cellular reprogramming in vivo may provide a novel approach to generate tumors for which the cell of origin is uncertain.
Project description:Merkel cell carcinoma (MCC) is an aggressive skin cancer with high propensity for metastasis, caused by Merkel cell polyomavirus (MCPyV), or chronic UV-light-exposure. How MCPyV modulates immune responses within the tumor microenvironment and how such are linked to patient outcomes remain unknown partly due to technical barriers to understanding the spatial organization of the tumor microenvironment at single-cell resolution. We interrogated the cellular and transcriptional landscapes of 60 MCC-patients using Co-detection-by-indexing (CODEX) and targeted bulk RNA sequencing. Notably, we identified an enrichment of dysfunctional T cells spatially associating with CXCL9+ myeloid cells at the tumor invasive front as key feature of virus-positive MCC. While MCPyV-positivity and CD8+ T cell infiltration correlated with metastasis-free-survival, responses to immune checkpoint blockade were high regardless of virus-status. Instead, we found an enrichment of central memory T cells within tertiary-lymphoid-structures that associated with response to immune-checkpoint blockade. These findings highlight fundamental differences in the organization of the native tumor microenvironment of virus-positive MCC, that are linked to differential survival outcomes and could be used for personalized treatment strategies.