Dataset Information

Piwil-2 is associated with advanced tumor stage and poor outcome in Merkel cell carcinomas

ABSTRACT: Merkel cell carcinomas (MCCs) are rare, highly aggressive skin cancers with poor outcome due to early lymphatic tumor spread and frequent recurrences. MCCs mostly occur in the head and neck and are mainly caused by an infection with the Merkel cell polyomavirus (MCPyV). Increasing evidence suggests that Piwil-2 and small non-coding PIWI-interacting RNAs (piRNAs) play an important role in solid malignancies and we thought that this might also be the case for MCCs. Therefore, Piwil-2 expression was first evaluated in 27 MCC specimens and correlated with oncological outcome. We found an association with high Piwil-2 expression and advanced tumor stage, MCPyV positivity and poor outcome. Next, we utilized siRNAs for Piwil-2 knock-down in MCC cells. Downregulation of Piwil-2 caused a significant change of 202 different piRNAs and 419 proteins. Interestingly, proteins related to viral driven MCC pathways (TRRAP, BRD8, PRIM2, ORC4) were significantly downregulated. Moreover, there was a moderate cell cycle arrest of cells in the G0/G1-phase, as well as a significant upregulation of SOX-2, a key regulator of Merkel cells. Altogether, Piwil-2 poses a poor prognosticator in MCCs, which is linked to MCC oncogenesis and SOX-2. Further research is needed to better understand underlying mechanisms and to prove their clinical relevance.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

DISEASE(S): Merkel Cell Carcinoma

SUBMITTER: Klaus Kratochwill

LAB HEAD: Dr Klaus Kratochwill

PROVIDER: PXD059625 | Pride | 2025-11-17

REPOSITORIES: Pride

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Piwil-2 represents a poor prognosticator in Merkel cell carcinomas that regulates oncoproteins, cell cycle arrest and SOX-2 expression.

Janik Stefan S Pammer Johannes J Simader Elisabeth E Kotowski Ulana U Grasl Stefan S Houben Roland R Copic Dragan D Mildner Michael M Mitulovic Goran G Bilban Martin M Derdak Sophia S Unterwurzacher Markus M Kratochwill Klaus K Erovic Boban M BM

Scientific reports 20251110 1

Merkel cell carcinomas (MCCs) are rare, highly aggressive skin cancers with poor outcome due to early lymphatic tumor spread and frequent recurrences. MCCs mostly occur in the head and neck and are mainly caused by an infection with the Merkel cell polyomavirus (MCPyV). Increasing evidence suggests that Piwil-2 and small non-coding PIWI-interacting RNAs (piRNAs) play an important role in solid malignancies and we thought that this might also be the case for MCCs. Therefore, Piwil-2 expression wa ...[more]

PMID: 41213968

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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.

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