Solid tumors of childhood display specific serum microRNA profiles

Abstract

Background: Serum biomarkers for diagnosis and risk-stratification of childhood solid tumors would improve the accuracy and timeliness of diagnosis and reduce the need for invasive biopsies. We hypothesized that differential expression and/or release of microRNAs by such tumors may be detected as altered serum microRNA profiles. Methods: We undertook global quantitative RT-PCR microRNA profiling (n=741) on RNA extracted from 53 serum samples, representing 33 diagnostic cases of common childhood cancers plus 20 controls. Technical confirmation was performed in a subset of 21 cases, plus four independent samples. Results: We incorporated robust quality-control steps for RNA extraction, qRT-PCR efficiency and hemolysis quantification. We evaluated multiple methods to normalize global profiling data and identified that the ‘global-mean’ approach was optimal. We generated a panel of six microRNAs that were most stable in pediatric serum samples and therefore most suitable for normalization of targeted microRNA qRT-PCR data. Tumor-specific serum microRNA profiles were identified for each tumor type and selected microRNAs underwent confirmatory testing. We identified a panel of microRNAs (miR-124-3p/miR-9-3p/miR-218-5p/miR-490-5p/miR-1538) of potential importance in the clinical management of neuroblastoma, as they were consistently highly over-expressed in MYCN-amplified high-risk cases (MYCN-NB). We also derived candidate microRNA panels for non-invasive differential diagnosis of a liver mass (hepatoblastoma vs. combined MYCN-NB/NB), an abdominal mass (Wilms tumor vs. combined MYCN-NB/NB), and sarcoma subtypes. Conclusions: This study describes a pipeline for robust diagnostic serum microRNA profiling in solid tumors of childhood, and has identified candidate microRNA profiles for prospective testing. Impact: We propose a new non-invasive method to diagnose childhood solid tumors