The histological analysis of adrenal
tumors is difficult and requires great expertise. Tissue
microRNA (
miRNA) expression is distinct between benign and malignant
tumors of several organs and can be useful for diagnostic purposes.
MiRNAs are stable and their expression can be reliably reproduced from archived
formalin-fixed,
paraffin-embedded (FFPE) tissue blocks. Our purpose was to assess the potential applicability of combinations of literature-based
miRNAs as markers of adrenocortical
malignancy. Archived FFPE tissue samples from 10
adrenocortical carcinoma (ACC), 10
adrenocortical adenoma (ACA) and 10 normal adrenal cortex samples were analyzed in a discovery cohort, while 21 ACC and 22 ACA patients were studied in a blind manner in the validation cohort. The expression of
miRNA was determined by RT-qPCR. Machine learning and neural network-based methods were used to find the best performing
miRNA combination models. To evaluate diagnostic applicability, ROC-analysis was performed. We have identified three
miRNA combinations (hsa-miR-195 + hsa-miR-210 + hsa-miR-503; hsa-miR-210 + hsa-miR-375 + hsa-miR-503 and hsa-miR-210 + hsa-miR-483-5p + hsa-miR-503) as unexpectedly good predictors to determine adrenocortical
malignancy with sensitivity and specificity both of over 90%. These
miRNA panels can supplement the histological examination of removed
tumors and could even be performed from small volume adrenal biopsy samples preoperatively.