Endocrine Abstracts

Background: Plasma microRNAs (miRs) (miR-4446-3p, miR-215-5p, miR-342-5p) were downregulated in patients with active acromegaly (AM) compared with healthy control subjects as assessed by next-generation sequencing.

Aim: The aim of this study wasto validate the previously observed finding in the newly enrolled patients with AM using qRT-PCR.

Materials and methods: Morning plasma samples were collected from fasting patients with AM and age- and sex-matched healthy controls and stored at –80°C. Total RNA isolation:QIAcube with miRNeasy Mini Kit. Reverse transcription was done by TaqMan Advanced miRNA cDNA Synthesis Kit. MicroRNA expression assessed by StepOnePlus Real-Time PCR system with TaqMan Advanced miRNA Assay. We measured plasma expression of five microRNAs: miR-4446-3p, miR-215-5p, miR-342-5p, miR-210-3p and miR-146a-5p. We performed IHC for SSTR2 and SSTR5 expression in tissue samples of patients who underwent neurosurgery. For correlation analysis, we used Kendall rank correlation coefficient.

Results: We enrolled 47 patients with AM – mean age 45.3 years (95% CI 41.5–49.1), body mass index (BMI) 29.9 kg/m² (28.3–31.6), gender ratio (m:f) 14:33, IGF-1–710.65 ng/ml (637.84–783.46) and 28 healthy controls matched by age and gender (mean age 44.3 years (39.1–49.5), body mass index (BMI) 27.7 kg/m² (25.09–29.45), gender ratio (m:f) 9:19). We found three microRNAs to be downregulated in AM compared with healthy controls. MiR-4446-3p: 0.471 (0.386–0.556) in AM vs 1.023 (0.866–1.180) in healthy controls (P < 0.001, FDR < 0.001). Similarly, miR-215-5p–0.360 (0.263–0.457) in AM vs 0.994 (0.761–1.228) in healthy controls (P < 0.001, FDR < 0.001). Differences in miR-146a-5p levels was 1.201 (1.015–1.387) in AM vs 1.585 (1.272–1.898) in healthy controls (P = 0.036, FDR = 0.06). Postoperative adenoma samples were obtained from 42 patients and stained for SSTR2 and SSTR5 expression. Correlation analysis showed positive correlations between GH levels and tumor volume as measured by MRI (0.65, P < 0.001), SSTR5 expression and tumor volume (0.33, P < 0.05), miR-210-3p and miR-146a-5p levels (0.28, P < 0.05); negative correlation between miR-146a-5p and SSTR2 expression (− 0.32, P < 0.05).

Conclusions: In this validation study we confirmed a downregulation of plasma miR-4446-3p, miR-215-5p and miR-146a-5p in patients with AM vs healthy subjects, which makes them promising biomarkers for further research.