MicroRNA profiling in Arrhythmogenic Cardiomyopathy and prognostic markers

Background: Arrhythmogenic cardiomyopathy (AC) is a clinically and genetically heterogeneous myocardial disease, characterised by a progressive myocardial dystrophy with fibro-fatty replacement, and represents one of the major causes of sudden cardiac death in the young and athletes. Although half of AC patients harbour private desmosomal gene mutations, their low and age-dependent penetrance suggests the involvement of other regulatory molecules. MicroRNAs (miRNAs) are a group of endogenous short noncoding RNAs that regulate gene expression by sequence-specific recognition of their target transcripts. They have been associated with numerous pathophysiological conditions, including cardiovascular diseases; however, their role as key regulatory molecules in AC as well as their impact on the onset and progression of the disease is largely unknown. Purpose: miRNA profiling in genotype-positive AC-patients with different gene mutations in order to identify their potential as AC biomarkers. Methods: The study involved 59 subjects with a definite AC diagnosis, previously genotyped, and 14 healthy controls. 84-miRNA array was applied on 8 frozen right-ventricle (RV) myocardial tissue samples, from heart transplanted AC patients; 9 whole blood samples, from patients with definite AC diagnosis, and 6 healthy controls (HC). In the validation study, seven miRNAs were analysed on 42-AC and 8-HC blood samples. miRNA analysis was performed by qPCR, relative quantification ΔΔCt method and in silico target prediction. All data were expressed in fold-change values. Receiver operating characteristic (ROC) analysis was performed on validated miRNAs. Results: miRNA profiling on AC-tissue samples displayed a genotype-related profile, 19 miRNAs were differentially expressed in PKP2 carriers, 15 in DSP carriers and 14 in DSG2 carriers, when compared to healthy controls. A common signature between PKP2 and DSP carriers was identified with 14 miRNAs in common (PKP2/DSP profile). None of these miRNAs were shown within DSG2 profile. In silico target prediction identified Hippo Signaling Pathway as a common target for both profiles. Analysis of AC-tissue samples as a unique group confirmed 26 differentially expressed miRNAs (AC-tissue profile) with predicted targets in the AC pathway. AC-blood miRNA profiling demonstrated a 14-miRNA signature, with 10 miRNAs differentially expressed in common with AC-tissue profile. Hsa-miR-144-3p, -122-5p, -208a-3p and -494-3p as well as hsa-miR-21-5p, -155-5p and -320a were analysed on a larger cohort of 42-AC and 8-HC. Only hsa-mir-122-5p was significantly overexpressed (p-value