Warren Simon J, Xue Gloria R, Zhou Hong-Ming, Alomari Ahmed K, Turner Matthew J
Departments of Dermatology and Pathology, University of Michigan, 36-1221-15, 2800 Plymouth Rd, Building 35, Ann Arbor, MI, 48109-2800, USA.
Department of Dermatology, Indiana University, Indianapolis, IN, USA.
Virchows Arch. 2025 Jul 28. doi: 10.1007/s00428-025-04182-7.
Microsatellites in melanoma are physically separate from the primary tumor, are hypothesized to arise by lymphovascular invasion similar to other metastases, and have not been previously studied at the molecular level. We compared gene expression in microsatellites with the matched primary melanoma in two patients using spatial transcriptomics. We identified recurrently altered genes in microsatellites contributing to vascular invasion (ITGA4, MCAM), survival in the circulation (CXCL8, PDGFRB, CDH1), vascular exit (ITGB2), survival at metastatic sites (C3, TGBFI), matrix remodeling (MMP9, VCAN, FN1, BGN), and angiogenesis (EMILIN2). Gene set enrichment analysis confirmed a metastatic signature in comparison to genes upregulated and downregulated in distant melanoma metastases, and identified pathway enrichment for NFKB, CDH1, and ZEB1 signaling. Microsatellites exhibited increased host immune responses and four recurrently overexpressed mediators of immune evasion were present (PAEP, GDF15, CD74, HLA-DRA) implying selection pressure from the increased immune response. Seven additional non-recurrent mediators of immune evasion were identified in microsatellites, overexpressed up to 58-fold in microsatellites. PAEP was 275-fold and 25-fold overexpressed, respectively, in microsatellites in two cases. We studied PAEP protein expression by immunohistochemistry in a larger group of 12 and found overexpression in microsatellites in five of 12 patients. PAEP was detected by immunohistochemistry in a microsatellite and also in a subclone within its primary, raising the possibility that the immunostain identifies the subclone in the primary responsible for the microsatellite. These preliminary findings suggest that melanoma microsatellites are true metastases at the level of gene expression, accounting for the sharply increased risk of disease progression in patients with microsatellites.
黑色素瘤中的微卫星在物理上与原发性肿瘤分离，据推测其产生是通过类似于其他转移灶的淋巴管侵袭，并且此前尚未在分子水平上进行研究。我们使用空间转录组学比较了两名患者微卫星与匹配的原发性黑色素瘤中的基因表达。我们在微卫星中鉴定出了与血管侵袭（整合素α4、黑色素瘤细胞粘附分子）、循环存活（趋化因子配体8、血小板衍生生长因子受体β、钙粘蛋白1）、血管外渗（整合素β2）、转移部位存活（补体C3、转化生长因子β诱导蛋白）、基质重塑（基质金属蛋白酶9、多功能蛋白聚糖、纤连蛋白1、基底膜聚糖）和血管生成（弹性微丝蛋白2）相关的反复改变的基因。基因集富集分析证实，与远处黑色素瘤转移灶中上调和下调的基因相比，微卫星具有转移特征，并确定了核因子κB、钙粘蛋白1和锌指E盒结合蛋白1信号通路的富集。微卫星表现出宿主免疫反应增强，并且存在四种反复过度表达的免疫逃逸介质（妊娠相关血浆蛋白A、生长分化因子15、CD74、人 HLA-DR抗原α链），这意味着来自增强免疫反应的选择压力。在微卫星中还鉴定出另外七种非反复出现的免疫逃逸介质，在微卫星中过度表达高达58倍。在两个病例中，妊娠相关血浆蛋白A在微卫星中分别过度表达275倍和25倍。我们通过免疫组织化学研究了更大一组12例患者中妊娠相关血浆蛋白A的蛋白表达，发现12例患者中有5例微卫星中存在过度表达。通过免疫组织化学在一个微卫星以及其原发性肿瘤内的一个亚克隆中检测到了妊娠相关血浆蛋白A，这增加了免疫染色识别原发性肿瘤中负责微卫星的亚克隆的可能性。这些初步发现表明，黑色素瘤微卫星在基因表达水平上是真正的转移灶，这解释了微卫星患者疾病进展风险急剧增加的原因。
