Assessment of the expression level of miRNA molecules using a semi-quantitative RT-PCR approach

Type 2 diabetes is one of the most prevalent diseases, which increases resistance to insulin in target tissues. The measurement of miRNAs quantity is a molecular approach for diagnosis of diabetes. miRNAs are small non-coding RNA strings of 21–23 long nucleotides that act as inhibitors in proteins translation. Several methods including Northern blot, qRT-PCR and Microarray have been used for diagnosis of miRNA molecules. Real time PCR is an expensive and accurate quantitative method that is widely used in miRNA studies. The miR-21 is an important miRNA in diabetes. In this study, for the first time, a semi-quantitative protocol was developed to quantify different amounts of a synthetic miR-21. In addition to semi-quantitative method, the miR-21 quantity was determined by quantitative method in several patients with type 2 diabetes and healthy people. The results indicated that there was a direct relationship between the amount of synthetic miR-21 and the intensity of the PCR bands. We also showed that the expression of miR-21 in people with type 2 diabetes increased compared to healthy people. The results were observed by both quantitative and semi-quantitative methods. The real-time RT-PCR was more sensitive than semi-quantitative PCR in identification of miRNAs. However, semi-quantitative PCR method benefited from higher simplicity and lower costs for defining general patterns of miRNA expression.