Gambichler Thilo, Dreißigacker Max, Kasakovski Dimitri, Skrygan Marina, Wieland Ulrike, Silling Steffi, Gravemeyer Jan, Melior Anita, Cherouny Angela, Stücker Markus, Stockfleth Eggert, Sand Michael, Becker Jürgen C
Department of Dermatology, Skin Cancer Center, Ruhr-University Bochum, Bochum, Germany.
National Reference Center for Papilloma- and Polyomaviruses, Institute of Virology, University of Cologne, Cologne, Germany.
J Dermatol. 2021 Jan;48(1):64-74. doi: 10.1111/1346-8138.15611. Epub 2020 Nov 12.
The relevance of Hedgehog signaling in Merkel cell carcinoma has only been addressed by a few studies with conflicting results. Thus, we aimed to establish the expression of Hedgehog signaling molecules in Merkel cell carcinoma to characterize causes of aberrant expression and to correlate these findings with the clinical course of the patients. Immunohistochemistry was performed for Sonic, Indian, Patched 1 (PTCH1) and Smoothened on patients' tumor tissue. Respective mRNA expression was analyzed in 10 Merkel cell carcinoma cell lines using quantitative real-time polymerase chain reaction. PTCH1 sequencing and DNA methylation microarray analyses were carried out on tumor tissues as well as cell lines. PTCH1 immunoreactivity in Merkel cell carcinoma was similar to that of basal cell carcinomas, which both significantly differed from PTCH1 immunoreactivity in healthy skin. Most PTCH1 mutations found were synonymous or without known functional impact. However, on average, the promoter regions of both PTCH1 were hypomethylated independently from PTCH1 gene expression or Merkel cell polyomavirus status. PTCH1 and GLI1/2/3 genes were differently expressed in different cell lines; notably, there was a significant correlation between GLI2 and PTCH1 mRNA expression. Similar to PTCH1 protein expression in patient tissues, PTCH1 gene expression in Merkel cell carcinoma cell lines is highly variable, but due to the similar methylation pattern across Merkel cell carcinoma cell lines, effects other than methylation seem to be the reason for the differential expression and PTCH1 appears to be upregulated by GLI as a classical Hedgehog target gene.
刺猬信号通路在默克尔细胞癌中的相关性仅在少数研究中得到探讨，且结果相互矛盾。因此，我们旨在确定刺猬信号通路分子在默克尔细胞癌中的表达情况，以阐明异常表达的原因，并将这些发现与患者的临床病程相关联。对患者的肿瘤组织进行了针对音猬因子、印地安刺猬因子、 patched 1（PTCH1）和 smoothened 的免疫组织化学检测。使用定量实时聚合酶链反应分析了 10 种默克尔细胞癌细胞系中各自的 mRNA 表达。对肿瘤组织和细胞系进行了 PTCH1 测序和 DNA 甲基化微阵列分析。默克尔细胞癌中 PTCH1 的免疫反应性与基底细胞癌相似，两者均与健康皮肤中的 PTCH1 免疫反应性显著不同。发现的大多数 PTCH1 突变是同义突变或无已知功能影响。然而，平均而言，PTCH1 两个启动子区域均呈低甲基化，与 PTCH1 基因表达或默克尔细胞多瘤病毒状态无关。PTCH1 和 GLI1/2/3 基因在不同细胞系中的表达不同；值得注意的是，GLI2 和 PTCH1 mRNA 表达之间存在显著相关性。与患者组织中 PTCH1 蛋白表达相似，默克尔细胞癌细胞系中 PTCH1 基因表达高度可变，但由于默克尔细胞癌细胞系中甲基化模式相似，甲基化以外的其他因素似乎是差异表达的原因，并且 PTCH1 似乎作为经典的刺猬靶基因被 GLI 上调。
