Chteinberg Emil, Kolarova Julia, Vogt Julia, Macamo Amanda, Bormann Felix, Kretzmer Helene, Speel Ernst Jan, van den Oord Joost, Schneider Christof, Stilgenbauer Stephan, Becker Jürgen C, Winnepenninckx Véronique, Biessen Erik, Zenke Martin, Kurz Anna Kordelia, Siebert Reiner, Zur Hausen Axel
Department of Pathology, GROW-Research Institute for Oncology and Reproduction, Maastricht University Medical Centre+, Maastricht, The Netherlands.
Institute for Biomedical Engineering, Department of Cell Biology, RWTH Aachen University Hospital, Aachen, Germany.
J Pathol. 2025 May;266(1):81-94. doi: 10.1002/path.6410. Epub 2025 Mar 4.
Merkel cell carcinoma (MCC) is a highly malignant skin cancer that expresses epithelial-, neuroendocrine-, and lymphoid-associated genes. Here, we focused on B-cell differentiation, which is characterised by the coexpression of PAX5 and TdT. PAX5 is the master regulator of B-cell commitment and is expressed in 65% of MCC cases. Yet little is known about the underlying molecular biology of the frequently reported PAX5 expression in MCC. Multi-omics analyses, including RNA next-generation sequencing, RT-qPCR, immunohistochemistry, and western blotting, were performed to assess PAX5 expression in MCC. Differential DNA methylation analysis at 61,043 PAX5 binding sites in enhancer and promoter elements was performed to detect differences between n = 14 MCC tissues and n = 91 various normal B-cell populations. RNA analysis revealed full-length PAX5 expression in MCC at the transcriptional level using both PAX5 transcription start sites. PAX5 protein expression was found in 40 of 41 MCCs and six out of seven MCC cell lines. DNA methylation array analysis revealed 1,084 hypermethylated loci of enhancer and promoter elements located in PAX5 binding sites in MCC. Of these, 702 loci were associated with 257 genes that are not expressed. The PAX5-associated regulatory elements of these 257 genes were enriched for interferon regulatory factor 4 (IRF4) and SPi-proto-oncogene (SPI1) binding motifs. Neither IRF4 or SPI1 could be detected in MCC on RNA or the protein level. Thus, because of the absence of these transcription factors, we conclude that full-length PAX5 alone cannot induce B-cell differentiation. © 2025 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.
默克尔细胞癌（MCC）是一种高度恶性的皮肤癌，可表达与上皮、神经内分泌和淋巴相关的基因。在此，我们聚焦于以配对盒基因5（PAX5）和末端脱氧核苷酸转移酶（TdT）共表达为特征的B细胞分化。PAX5是B细胞定向分化的主要调节因子，在65%的MCC病例中表达。然而，对于MCC中频繁报道的PAX5表达的潜在分子生物学机制知之甚少。我们进行了包括RNA下一代测序、逆转录定量聚合酶链反应（RT-qPCR）、免疫组织化学和蛋白质免疫印迹在内的多组学分析，以评估PAX5在MCC中的表达。对增强子和启动子元件中61043个PAX5结合位点进行差异DNA甲基化分析，以检测14例MCC组织与91个不同正常B细胞群体之间的差异。RNA分析显示，在转录水平上，使用PAX5的两个转录起始位点均检测到MCC中全长PAX5的表达。在41例MCC中的40例以及7株MCC细胞系中的6株中发现了PAX5蛋白表达。DNA甲基化阵列分析显示，MCC中位于PAX5结合位点的增强子和启动子元件有1084个高甲基化位点。其中，702个位点与257个未表达的基因相关。这257个基因的PAX5相关调控元件富含干扰素调节因子4（IRF4）和原癌基因SPI1（SPI1）结合基序。在MCC的RNA或蛋白质水平上均未检测到IRF4或SPI1。因此，由于缺乏这些转录因子，我们得出结论，单独的全长PAX5不能诱导B细胞分化。© 2025作者。《病理学杂志》由约翰·威利父子有限公司代表大不列颠及爱尔兰病理学会出版。
