Aims: Liraglutide 3 mg once daily is an approved, prescription injectable Glucagon Like Peptide-1 receptor agonist that, when used with a low-calorie diet and increased physical activity, can reduce excess weight in patients with obesity. MiRNAs are small non-coding single stranded RNAs that regulate gene expression post-transcriptionally by inhibiting their mRNA target translation into proteins. MiRNAs can be secreted in the blood stream and affect the molecular pathways of distal cells. Several studies have demonstrated that obese patients express a differential pattern of circulating miRNAs compared to lean subjects. The effects of liraglutide in circulating miRNAs remain largely unknown.
Methods: To investigate whether treatment with 3 mg liraglutide can affect the level of circulating miRNAs, we tested the expression of several miRNAs in the plasma of 16 patients with obesity enrolled in a clinical trial at baseline and after 8 weeks of treatment with qPCR analysis using the Locked Nucleic Acid technology. RNA was extracted using miRNeasy Serum/Plasma Advanced Kit (Qiagen) and reverse transcribed into cDNA using miRCURY Universal RT Kit (Qiagen). MiRNA expression was analysed using SYBR green (Sigma) and LNA primer assays (Qiagen). Cel-miR-39-3p and Unisp6 spike-ins were used as controls of RNA extraction and reverse-transcribed respectively to normalise the expression of the miRNAs of interest.
Results: At baseline, participants had a mean weight of 120.5 kg (±19.64) and BMI of 42.18 kg/m2. At week 8, participants had lost a mean of −6.1 kg (S.D.± 2.39) of body weight (P<0.01). Among the tested miRNAs, expression of miR-424 was significantly (P=0.008) decreased after 8 weeks of treatment. Statistical analysis was performed using paired, two-tailed student t-test with level of significance set at P<0.05.
Conclusions: Despite growing interest in the roles of obesity induced miRNAs in insulin resistance and T2DM, their molecular targets and regulation mechanism are not completely understood. According to evidence, upregulated expression of miR-424 impairs insulin-signaling and insulin-induced glycogen synthesis in hepatocytes of patients with obesity. Herein we demonstrate that miR-424 induced by obesity is reduced after treatment with liraglutide and this could be a potential weight-loss independent mechanism of action by which liraglutide exerts its beneficial effects on insulin resistance.