Metformin decreases miR-122, -223 and -29a in women with polycystic ovary syndrome

Metformin is associated with increased insulin sensitivity, whereas oral contraceptive pills (OCP) could increase the risk for type 2 diabetes (T2D) in women with Polycystic Ovary Syndrome (PCOS). Certain microRNAs (miRNAs) might serve as biomarkers for the risk of T2D. The aim of this study was to investigate changes in circulating miRNA levels during treatment with metformin and OCP in women with PCOS. Sixty-five women with PCOS according to Rotterdam criteria were randomized to metformin (2g/d), metformin+OCP (150 mg desogestrel + 30 µg ethinylestradiol) or OCP alone for 12 months. Serum miRNA analysis was performed with individual RT-qPCR or Taqman Low Density Array cards of 22 selected miRNAs previously related to PCOS, glucose and/or lipid metabolism. MiR-122 and miR-29a levels were decreased after treatment with metformin compared with metformin+OCP and OCP group: miR-122: log2 difference -0.7 (p= 0.01) and -0.7 (p= 0.02), miR-29a: log2 difference -0.5 (p= 0.01) and -0.4 (p= 0.04), while miR-223 levels were decreased in the metformin+OCP group after treatment: log2 difference -0.5 (p=0.02). During the treatment period, a significant weight loss was observed in the metformin group compared with the OCP group. In the OCP group, miRNA levels were unchanged during the treatment period. Levels of circulating miRNAs associated with lipid and glucose metabolism decreased during metformin treatment. Changes in miRNA levels in the metformin group could be explained by the simultaneous weight loss in the same group. These results support the notion that metformin treatment alone may be superior for metabolic health compared with OCP. vers. 26, IBM, US) and GraphPad Prism (vers. 8.1.1, GraphPad Inc., La Jolla, CA, US). Correlation plots were generated with R (vers. 3.5.3), R Studio (vers. 1.2.1335) and statistical package Corrplot (vers. 0.84). All data were tested with the Shapiro-Wilk test for normal distribution. Non-normally distributed data were logarithmically transformed. Data are presented as medians and interquartile range (IQR) and miRNA levels as log fold change between indicated groups. For statistical analysis, grouped data were compared with Students’ t-test for unpaired and paired samples. For more than two comparisons, one-way ANOVA with Tukeys’ post hoc uptake in hepatic cells 54 . The association between insulin resistance and miR-223 is also well established; miR-223 is upregulated in adipose tissue in women with insulin resistance, both with and without PCOS 55 , but miR-223 is upregulated also in serum from patients with diabetes and obesity 56,57 . MiR-223 was suggested to target GLUT4 58 , and upregulation of miR-223 was shown to decrease GLUT4 protein content and glucose uptake in adipose tissue 55 . These results were in accordance with our results, as we found a miR-155 was negatively correlated with androstenedione and 17OH-progesterone. Unfortunately, we have not tested miR-155 in our study, as the custom Taqman array cards for our study was designed prior to this publication. In conclusion, we investigated the effect of different treatment modalities of PCOS on miRNA levels. We did not see an effect of OCP-treatment on miRNA levels. These results suggest that while PCOS is a condition of hyperandrogenism, pharmacological intervention with OCPs to decrease hyperandrogenism did not change miRNAs previously associated with PCOS and metabolic syndrome. The most significant changes in miRNA levels were caused by metformin treatment, and the changes were seen in miRNAs previously associated with insulin resistance, obesity and liver damage, especially miR-122, miR-29a and miR-223. It appears likely that metformin, having a large effect on liver metabolism by suppressing hepatic glucose production 61 , concomitantly decreases the level of several liver expressed circulating miRNAs and that this could indicate improved hepatic health. Correlations between Δ values for significantly altered miRNAs and Δ values for significantly altered clinical measurements during the study assessed with Spearman’s Rho. Unadjusted. The correlations between Δ miR-636 and Δ fat legs and Δ fat trunk, respectively, were insignificant when adjusting for BMI at inclusion and treatment group. Similar, was the correlation between Δ miR-122 and Δ FG score insignificant after adjustment, while the correlation between Δ miR-29a and Δ FG score remained significant. FG: Ferriman Gallwey, T: testosterone, SHBG: Sex hormone binding globulin*p<0.05,