Dysregulation of TTN Gene Expression, Titin Protein Levels, and Circulating ncRNAs (miR-200a, lncRNA FOXD2-AS1, and snoRNA-42) in Dilated Cardiomyopathy: A Pilot Study

Abstract

Dilated Cardiomyopathy is the major cause of congestive heart failure and sudden cardiac death. It is a type of cardiomyopathy characterized by ventricular dilatation, wall thinning and systolic dysfunction. TTN gene is implicated in DCM and encodes for giant titin protein. This study explores the association between TTN gene expression with some types of non-coding RNAs in DCM patients. The study comprised three age- and sex-matched groups (20 individuals each): healthy controls, male patients, and female patients. Relative expression levels of TTN, miR-200a, lncRNA FOXD2-AS1, and snoRNA-42 were quantified using qRT-PCR, whereas serum titin protein levels were measured via ELISA. TTN gene expression was significantly elevated in both male and female DCM patients compared with controls (P<0.001). Furthermore, miR-200a and snoRNA-42 levels were also significantly increased in DCM patients particularly in females. In contrast, lncRNA FOXD2-AS1 was significantly decreased in both sexes of DCM patients. ROC curve analysis for TTN gene demonstrated high diagnostic performance, sensitivity and specificity with (P=0.0022), supporting TTN as a reliable molecular biomarker for DCM. Similarly, miR-200a showed strong diagnostic potential, particularly in females (P=0.0275 in males and P=0.0022 in females), underscoring its efficiency as a sex-specific biomarker. Furthermore, Titin protein level was significantly elevated in DCM patients, particularly in females. Pearson correlation analysis detected a negative correlation between miR-200a and TTN mRNA in both males and females, negative correlations were also observed between miR-200a and titin protein levels. In contrast, TTN gene expression and titin protein levels showed a positive correlation, indicating transcription-driven increases in titin level. To the best of our knowledge, this is the first study in Iraq, particularly in Mosul, to integrate Titin protein and TTN gene expression with multiple circulating ncRNA classes (miR-200a, lncRNA FOXD2-AS1 and snoRNA-42) in patients with DCM. The combined analysis of TTN gene / Titin protein axis and ncRNAs within a clinical group from Mosul city provides a comprehensive view of post-transcriptional regulation and revealed sex-dependent molecular differences. Moreover, the strong diagnostic performance of TTN and miR-200a supports their potential as non-invasive biomarkers for DCM. By focusing on a Middle Eastern population, this study contributes novel region-specific molecular data and expands current understanding of DCM beyond previously studied populations. In DCM patients the expression level of TTN gene was significantly increased, demonstrating that transcriptional activation was correlated with myocardial remodeling. The dysregulated expression of ncRNAs (miR-200a, lncRNA FOXD2-AS1 and snoRNA-42), suggested the existence of a complex post-transcriptional regulatory network affecting TTN expression. All of these findings highlight the potential of TTN and ncRNA signatures as promising non-invasive molecular biomarkers for DCM.