Background: Inhibition of immune checkpoint proteins is effective in adult cancers but has shown limited efficacy in pediatric cancers. While factors regulating expression of immune checkpoint proteins such as PD-L1 are well documented in adult cancers, their regulation is poorly understood in pediatric cancers.

Methods: We analyzed Wilms tumor specimens with reverse-phase protein arrays. We validated correlations using published sequencing data, flow cytometry, and immunoblots.

Results: Using unsupervised clustering of protein arrays, we found that immune markers like PD-L1 are upregulated in distinct subsets of Wilms tumor, the most common pediatric kidney cancer. Specifically, chemotherapy-exposed Wilms tumor specimens exhibited higher levels of PD-L1 expression, and common chemotherapeutics upregulated PD-L1 in vitro. Furthermore, mutations in CTNNB1 and DROSHA, the two most commonly mutated genes in Wilms tumor, correlated with higher PD-L1. Activation of Wnt/β-catenin signaling and knockdown of DROSHA or DICER1 both increase PD-L1 in vitro.

Conclusions: Together, our results identify clinical and biological properties regulating PD-L1 in Wilms tumor that may inform precision therapy approaches in pediatric immuno-oncology.

Keywords: immunotherapy; molecular genetics; wilms tumor.

© 2025 The Author(s). Pediatric Blood & Cancer published by Wiley Periodicals LLC.

背景： 免疫检查点蛋白的抑制在成人癌症中有效，但在儿童癌症中的疗效有限。虽然在成人癌症中已经详细记录了调节如PD-L1等免疫检查点蛋白表达的因素，但对于儿童癌症中的这些因素调控机制了解较少。

方法： 我们使用反相蛋白质阵列分析了Wilms肿瘤样本，并通过已发表的测序数据、流式细胞术和免疫印迹验证了相关性。

结果： 利用蛋白质阵列的无监督聚类，我们发现如PD-L1等免疫标记物在不同的Wilms肿瘤亚群中上调。具体来说，接受过化疗的Wilms肿瘤样本表现出更高的PD-L1表达，并且常用的化疗药物体外可以上调PD-L1。此外，在Wilms肿瘤中最常突变的CTNNB1和DROSHA基因突变与更高的PD-L1水平相关。Wnt/β-catenin信号通路的激活以及DROSHA或DICER1的敲低都可以在体外增加PD-L1。

结论： 我们的结果共同识别了Wilms肿瘤中调节PD-L1的临床和生物学特性，这些可能为儿童免疫肿瘤学中的精准治疗策略提供信息。

关键词： 免疫疗法；分子遗传学；Wilms肿瘤。