Solid tumours of childhood display specific serum microRNA profiles.
Robust serum biomarkers for the diagnosis and risk-stratification of childhood solid tumours would improve the accuracy and timeliness of diagnosis and reduce the need for invasive biopsies. We hypothesised that the differential expression and/or release of microRNAs by such tumours may be detected as altered serum microRNA profiles.
We undertook global quantitative reverse-transcription polymerase-chain-reaction (qRT-PCR) microRNA profiling (n=741) on RNA extracted from 54 serum samples, representing 34 cases of common childhood cancers at the time of diagnosis, plus 20 matched controls. Subsequent hypothesis testing was done in a partially-independent subset of 25 samples. We incorporated robust quality-control steps for RNA extraction, qRT-PCR efficiency and haemolysis quantification. We evaluated multiple methods to normalise global profiling data and identified that the 'global mean' approach was optimal. We generated a panel of six microRNAs that were most stable in paediatric serum samples and therefore most suitable for normalisation of targeted microRNA qRT-PCR data.
Tumour-specific serum microRNA profiles were identified for each tumour 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) compared with MYCN-amplified low-risk neuroblastoma (NB), other tumours and the control group. We also derived candidate microRNA panels for non-invasive differential diagnosis of an abdominal mass (Wilms tumour vs. combined MYCN-NB/NB), liver mass (hepatoblastoma vs. combined MYCN-NB/NB) and sarcoma subtypes.
This study demonstrates the feasibility of robust diagnostic serum microRNA profiling in solid tumours of childhood, and has identified candidate microRNA profiles for testing in larger, prospective studies.
We would like to gratefully acknowledge Theo Giannopoulos and Susanne Booth at Castle Hill Hospital for their help in acquiring ovarian tissue samples, and Jane Smales for coordinating the clinical aspects of the study. This study is funded by a grant from NC3Rs (Registry File: G1100600).
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