DCM is a serious complication associated with diabetesand increasing incidence rate; however, the molecular mechanism underlying the development of DCM is unclear. Therefore, studying its mechanism and determining molecular targets for diagnosis and treatment are essential. Some studies have found that mRNAs, miRNAs, lncRNAs, and TFs play important regulatory roles in the development of DCM 2, 3. In this study, we firstly performed a comprehensive bioinformatics analysis to identify the miRNAs, lncRNAs, immune genes, and TFs in the interaction network and reported the key genes related to DCM.
Noncoding RNAs (ncRNAs) have been proved to be of great significance in human life, health, and disease diagnosis. According to their functions, ncRNAs are classified as miRNAs, lncRNAs, and circular RNAs (circRNAs) 28. lncRNAs act as miRNA sponges that can regulate miRNA abundance and compete with mRNA for miRNA binding. miRNAs are considered to be potential tissue-specific biomarkers and play an important role in the pathogenesis of myocardial remodeling 29. They also contribute to the development of DCM by regulating oxidative stress, inflammation, cardiomyocyte apoptosis, and mitochondrial function 2. Previous study has reported that miRNA-195 inhibitors can reduce diabetic myocardial hypertrophy and improve cardiac function by reducing oxidative damage, inhibiting cell apoptosis, and promoting angiogenesis 30. Moreover, miRNAs are involved in the regulation of multiple biological functions in the mitochondria by binding to their target genes 31. The miR-30 family, including miR-30a, miR-30b, miR-30c, and miR-30d, is highly expressed in cardiomyocytes 32 and inhibits the expression of P53 to prevent mitochondrial division and cell apoptosis. The mechanisms by which miRNAs regulate the expression of genes involved in myocardial diseases and their effect on the development of diabetes have not yet been clearlyunderstood.
In this study, we analyzed the DEGs identified from the GSE21610 and GSE112556 datasets, which consist of the gene expression profiles of patients with DCM and healthy individuals. The results indicated that 13 miRNAs, 629 immune genes, 260 TFs, and 1044 lncRNAs were differentially expressed in patients with DCM. The DEGs were mainly enriched in the nuclei and cytoplasm; involved in the regulation of BPs and nucleic acid binding; and participated in the regulation of the cytokine–cytokine receptor interaction and the PI3K-Akt signaling pathway. These pathways are related to the development of DCM and chemokine signaling pathways. Our enrichment analysis results help in further studying the role of DEGs in DCM. To further analyze the key genes related to DCM, we constructed a PPI network, wherein 32 nodes were chosen as the hub nodes that consisted of 3 TFs and 22 immuGenes mRNAs. The lncRNA–miRNA–TF–immune gene pathway ceRNA network was constructed with 517 interactions, including 10 miRNAs, 2 lncRNAs, and 161 mRNAs (123 immune genes and 38 TFs).
TCGA dataset analyses indicated that aberrant expression of the hubgenes, including WDFY3.AS2, XIST, hsa-miR-144-5p, and hsa-miR-146b-5p, was significantly different between DCM and normal tissuesamples. Previous studies have shown that MiR-144 can target Nrf2 directly and down-regulated miR-144 is found to regulate oxidative stress in diabetic cardiomyocytes 33. MiR-146a plays a regulatory role with the NF-κB signaling pathway components, which is the key mediator of inflammation and hyperglycemia 34, 35. This is consistent with our finding. The roles of different miRNAs and lncRNAs, especially WDFY3.AS2, XIST, hsa-miR-144-5p, and hsa-miR-146b-5p, in the context of DCM should be further studied, including type 1 and type 2 diabetes, the contribution of pathophysiological mechanisms including inflammation, apoptosis, hypertrophy and fibrosis, and oxidative stress to the development of DCM.
Our dataset analyses also indicated the aberrant expression of the hub genes PIK3R1 and CCR9 between DCM and normal tissue. The enrichment results of PIK3R1 indicated that it was significantly enriched in the JAK-STAT signaling pathway, T Toll-like receptor signaling pathway, TNF signaling pathway, fluid shear stress, and atherosclerosis AGE-RAGE signaling pathway (which cause diabetic complications), and the chemokine signaling pathway. The JAK/STAT signaling pathway is an intracellular signaling pathway closely related to cardiac hypertrophy, which plays a key role in cell growth, survival and differentiation, and regulation of gene expression. It has been shown that high glucose activates the JAK/STAT signaling of vascular endothelial cells in vitro through phosphorylation of JAK2 and subsequently STAT3, leading to the proliferation of endothelial cells. Hyperglycemia, hyperlipidemia, and insulin resistance are the main causes of chronic low-grade inflammation of the diabetic heart. Cardiac Toll-like receptors and inflammasome complexes, probably through NF-B activation and ROS overproduction, may be key inducers for inflammation 36. Therefore, what role of PIK3R1 plays in regulation of JAK/STAT signaling pathway, T Toll-like receptor signaling pathway and others represents an important strategy for the treatment of DCM and needs to be further explored.
We also performed CMAP analysis to examine the potential small-molecule drugs that can be potentially used for treating DCM. The three most significant drugs identified were danazol, ikarugamycin, and semustine. Danazol is a medicine used to treat endometriosis, fibrocystic breast disease, hereditary angioedema and other diseases. Ikarugamycin is a previously discovered antibiotic which has been shown to inhibit clathrin-mediated endocytosis and the uptake of oxidized low-density lipoprotein in macrophages 37. Semustine is a drug used in chemotherapy 38. Although there is no relevant literature regarding the effect of these compounds on DCM treatment, we speculate that these small-molecule drugs may have the potential for effectively treating DCM by interfering with the expression of the hub genes.