Dysregulated miRNA Associated with Transcription Factors of Insulin Gene Expression in Chronic Pancreatitis

Abstract

Background/Aim: MicroRNAs with regulatory functions in gene expression are implicated in different diseases. The present study investigated differentially expressed miRNAs that possibly influence transcription factors involved in insulin gene expression in Chronic Pancreatitis (CP) employing bioinformatics approaches. Methods: Pancreatic tissues were collected from CP patients undergoing partial pancreatectomy (n = 16) and controls (n = 15) undergoing resections for non-pancreatic malignancies. MiRNA profiles obtained using microarrays were validated by qRT-PCR. Target search involving miRWalk and TarBase as well as functional annotation employing KEGG (Kyoto encyclopedia of genes and genomes) and DAVID (Database for Annotation) databases were performed. Ingenuity pathway analysis (IPA) was used to construct networks relating miRNAs to their target genes. mRNA and proteins related to insulin gene transcription factors and hormones were evaluated by qRT-PCR and western blotting followed by confirmation upon immunofluorescent staining. Results: Microarray data revealed 10 up-regulated and 15 down-regulated miRNAs in CP as compared to controls (Log2 FC > 2). Bioinformatic analysis showed 8399 target genes and KEGG pathway analysis suggested a role for the dysregulated miRNAs in modulating cytokine signaling, fibrosis, JAK-STAT signaling and insulin synthesis. IPA analysis suggested a simplified network attributing dysregulated miRNAs to NFκB-dependent cytokine signaling. Further, associations could be noted between miRNA 200b with Maf A, 138-1 with Neuro D and 27b with FoxO1. Decreases in mRNA levels of Pdx1, Neuro D and increases of Maf A and FoxO1 transcription factors could be noted (P < 0.01) in CP. These results were confirmed by western blotting and immunofluorescence staining. Conclusion: Our results identified dysregulation of miRNAs 138-1, 27b and 200b which were found to be associated with insulin gene transcription factors Neuro D, FoxO1 and Maf A respectively.