Phelps Hannah M, Pierce Janene M, Murphy Andrew J, Correa Hernan, Qian Jun, Massion Pierre P, Lovvorn Harold N
Vanderbilt University School of Medicine, Nashville, TN.
Vanderbilt University Medical Center, Department of Pediatric Surgery, Nashville, TN.
J Pediatr Surg. 2019 Jun;54(6):1198-1205. doi: 10.1016/j.jpedsurg.2019.02.030. Epub 2019 Feb 28.
BACKGROUND/PURPOSE: Wilms tumor (WT) is the most common childhood kidney cancer globally. Our prior unbiased proteomic screen of WT disparities revealed increased expression of Fragile X-Related 1 (FXR1) in Kenyan specimens where survival is dismal. FXR1 is an RNA-binding protein that associates with poor outcomes in multiple adult cancers. The aim of this study therefore was to validate and characterize the FXR1 expression domain in WT.
Quantitative FXR1 gene expression was compared between WT, adjacent, adult, and fetal kidney specimens. The cellular and subcellular expression domain of FXR1 was characterized across these tissues using immunoperoxidase staining. RNA-sequencing of FXR1 was performed from WT and other pediatric malignancies to examine its broader target potential.
FXR1 was detected in all clinical WT specimens evaluated (n = 82), and as a result appeared independent of demographic, histology, or adverse event. Specific cytosolic staining was strongest in blastema, intermediate and variable in epithelia, and weakest in stroma. When present, areas of skeletal muscle differentiation stained strongly for FXR1. qPCR revealed increased FXR1 expression in WT compared to adult and adjacent kidney (p < 0.0002) but was similar to fetal kidney (p = 0.648). RNA-sequencing revealed expression of FXR1 in multiple pediatric tumors, greatest in rhabdomyosarcoma and WT.
FXR1 was expressed consistently across this broad sampling of WT and most robustly in the primitive blastema. Notably, FXR1 labeled a specific self-renewing progenitor population of the fetal kidney.
背景/目的：肾母细胞瘤（WT）是全球最常见的儿童肾癌。我们之前对WT差异进行的无偏蛋白质组学筛查显示，在肯尼亚生存率极低的标本中，脆性X相关蛋白1（FXR1）的表达增加。FXR1是一种RNA结合蛋白，在多种成人癌症中与不良预后相关。因此，本研究的目的是验证和表征WT中FXR1的表达域。
比较WT、相邻组织、成人肾脏和胎儿肾脏标本中FXR1基因的定量表达。使用免疫过氧化物酶染色在这些组织中表征FXR1的细胞和亚细胞表达域。对WT和其他儿科恶性肿瘤进行FXR1的RNA测序，以检查其更广泛的靶标潜力。
在所有评估的临床WT标本（n = 82）中均检测到FXR1，因此其出现与人口统计学、组织学或不良事件无关。特异性胞质染色在胚芽组织中最强，在上皮细胞中中等且变化不定，在基质中最弱。当存在时，骨骼肌分化区域FXR1染色强烈。qPCR显示，与成人肾脏和相邻肾脏相比，WT中FXR1表达增加（p < 0.0002），但与胎儿肾脏相似（p = 0.648）。RNA测序显示FXR1在多种儿科肿瘤中表达，在横纹肌肉瘤和WT中表达最高。
在WT的广泛样本中，FXR1表达一致且在原始胚芽组织中表达最强。值得注意的是，FXR1标记了胎儿肾脏中特定的自我更新祖细胞群。
