Gene expression of distinct histological components of Wilms tumor analyzed under the perspective of kidney development. Homo sapiens

Gene expression analyses through cDNA microarray of unique Wilms tumor (WT) histological components, blastema (BL), epithelia (EP) and stroma (ST), from different patients were performed and compared with non-neoplastic mature and pool of fetal kidney (FK). We used a customized cDNA array containing 4 608 human genes and demonstrated that BL had over representation of genes with similar expression behavior to the earliest stage of normal renal development. Moreover, since WT is a result of loss of developmental control and gain of tumorigenic potential in a successive way, herein we identified genes whose expression level is altered during the kidney development and also in WT and classified as WT-kidney development set. From this set, a smaller group of 36 differentially expressed genes was derived, which was enriched by genes involved in signal transduction, such as APC, BZRP, MET, PLAU, GPR35 and TRADD. An over representation of genes belonging to the WNT signaling pathway were observed. Immunostaining assays of APC and beta-catenin were carried out in 108 specimens showing differential labeling localization in WT. Altogether our data show molecular evidences confirming the recapitulation of embryonic kidney by WT components and strongly suggest that the WNT signaling pathway plays a crucial role in Wilms tumorigenesis. Keywords: Wilms tumor, cDNA microarray, Histological components, WNT signaling pathway Overall design: We performed gene expression analyses by customized cDNA array using dye swap with reference design, of unique histological components of Wilms tumors (6 blastemal, 6 epithelial and 3 stromal components) from different patients and compared to 3 normal mature and a pool of fetal kidneys (triplicate). These differentially expressed lists were compared with available data of differentially expressed genes during kidney development.

本研究针对不同患者来源的肾母细胞瘤（Wilms Tumor, WT）特有组织学组分——芽基（blastema, BL）、上皮（epithelia, EP）与间质（stroma, ST），采用cDNA微阵列（cDNA microarray）开展基因表达分析，并与非肿瘤性成熟肾脏及胎儿肾脏混合样本（fetal kidney, FK）进行比对。本研究使用包含4608个人类基因的定制化cDNA微阵列，结果显示芽基组分中，与正常肾脏发育早期表达模式相似的基因呈现富集现象。
此外，鉴于肾母细胞瘤是发育调控失控并逐步获得致瘤潜能的产物，本研究筛选出在肾脏发育过程及肾母细胞瘤中均存在表达异常的基因，将其归类为WT-肾脏发育基因集。从该基因集中进一步筛选得到36个差异表达基因，其中富集了参与信号转导的基因，包括APC、BZRP、MET、PLAU、GPR35及TRADD。同时观察到属于WNT信号通路（WNT signaling pathway）的基因呈现显著富集。
本研究对108例肾母细胞瘤标本开展APC与β-连环蛋白（beta-catenin）免疫染色实验，结果显示二者在肿瘤组织中的标记定位存在差异。综上，本研究的分子生物学证据证实肾母细胞瘤组分可重现胚胎肾脏的发育特征，且有力提示WNT信号通路在肾母细胞瘤发生过程中发挥关键作用。
关键词：肾母细胞瘤（Wilms Tumor, WT）、cDNA微阵列（cDNA microarray）、组织学组分、WNT信号通路（WNT signaling pathway）
实验设计：本研究采用带参考样本的染料交换实验设计，通过定制化cDNA微阵列对不同患者来源的肾母细胞瘤特有组织学组分（6例芽基、6例上皮及3例间质组分）进行基因表达分析，并以3例正常成熟肾脏样本及1份混合胎儿肾脏样本（设置生物学重复三次）作为对照。将所得差异表达基因列表与已公开的肾脏发育过程差异表达基因数据进行比对分析。