A novel miRNA located in the GATA4 gene regulates the expression of IGF-1R and AKT1/2 genes and controls cell proliferation.

GATA4 gene is a zinc-finger transcription factor known to be involved in cardiogenesis and the progression of different cancer types. Its diverse functions might be attributed to noncoding RNAs that could be embedded within its sequence. Here, we predicted a stable RNA stem-loop structure that is located in the second intron of the GATA4 gene. Available microRNA (miRNA) sequencing data and molecular genetics tools confirmed the identity of a mature miRNA (named GATA4-miR1) originating from the predicted stem-loop. In silico analysis predicted IGF-1R and AKT1/2 genes as potential targets for GATA4-miR1. Indeed, direct interactions between GATA4-miR1 and 3' untranslated regions sequences of IGF-1R and AKT1/2 genes were documented by dual luciferase assay. In addition, overexpression of GATA4-miR1 in SW480 cells resulted in the reduction of IGF-1R and AKT1/2 genes' expression, detected by reverse transcription quantitative (RT-q) polymerase chain reaction and Western blot analysis. This observation was consistent with a deduced negative correlation between the expression patterns of GATA4-miR1 and IGF-1R genes during cardiomyocyte differentiation. Moreover, overexpressing GATA4-miR1 in SW480 and PC3 cells resulted in a significant increase of the sub-G1 population in both cell lines, as detected by propidium iodide flow cytometry. Further analysis by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay indicated a reduction in the survival and proliferation rates of SW480 cells overexpressing GATA4-miR1, but no impact was observed on apoptosis progression, as indicated by Annexin-V flow cytometry. Overall, GATA4-miR1 represents a promising candidate for further research in the fields of cancer and cardiovascular therapeutics.