ECE2015 Symposia Pathogenesis of adrenocortical tumours (3 abstracts)
MicroRNA (miRNA) are small RNA molecules involved in the posttranscriptional regulation of gene expression. Differential expression of miRNA has been described in several tumours. miRNA expression patterns can be used as markers of malignancy, as prognostic markers and even for the subclassification of tumours. miRNA markers can be especially useful for the diagnosis of tumours whose histological analysis is difficult such as adrenocortical cancer (ACC). Beside tissue miRNA, miRNA are also released into the circulation and these blood-borne circulating miRNA might have great potential as minimally invasive markers of malignancy. Several reports including ours have described potential tissue and circulating miRNA markers of ACC. The applicability of tissue miRNA as biomarkers is further extended due to their stability, and therefore formalin-fixed paraffin embedded tissue blocks can be used for miRNA analysis. Among tissue miRNA markers of malignancy, overexpressed miR-483-5p, the expressional difference of miR-503-miR-511 and underexpressed miR-195 are most promising showing high sensitivity and specificity values. Some miRNA markers might be exploited as prognostic markers, including miR-483-5p, miR-195, miR-503 and miR-210. Three studies to date have reported on circulating miRNA profiles in ACC. Overexpressed miR-483-5p, miR-100, miR-181b, miR-210 and miR-34a have been proposed as circulating miRNA markers of ACC. Circulating miR-483-5p and miR-195 might be exploited to distinguish aggressive and non-aggressive cancer forms. There are several technical problems associated with the analysis of circulating microRNAs that need to be overcome for their reliable use. miRNA expression patterns of aggressive and non-aggressive forms of ACC are different as established by next generation sequencing data. In conclusion, both tissue and circulating miRNA are promising biomarkers but most studies included only limited sample sets and there are significant differences among different studies. Sample size extension, the standardization of analytical approaches will be needed to confirm the suitability of miRNA markers in adrenal cancer.
Disclosure: Hungarian Scientific Research Grant (OTKA K100295).