The growth response in patients undergoing GH treatment is variable depending both on the patient's basal conditions and on personal innate sensitivity to therapy. MicroRNAs (miRNAs) are epigenetic regulators of gene expression, and are recognised as important regulators of biological and metabolic processes. It is unknown at present whether miRNAs could be early biomarkers of response to GH treatment in a perspective of individualised medicine, and whether they could disclose new information on the effects and regulation of GH.
We aimed at identifying all miRNAs varying on GH treatment using a global profiling approach, and at evaluating the principal pathways and biological processes, within growth, impacted by these miRNAs.
Ten prepubertal normal weight patients with IGHD were enrolled (5Males,5Females; CA:8,12±0,73yr). Global miRNA profiles (TaqMan Advanced Human CardA) were evaluated at -3, 0 and at +3 months on treatment. MiRNA expression levels at -3 and 0 months were compared and the miRNAs showing a p-value=0.05 were excluded allowing to identify those miRNAs changing only in response to treatment (+3 months) by either a factor Log22-DDCt>+1.5 or Log22-DDCt<-1.5 (up- or down-regulated, respectively). Single miRNA target genes were evaluated and DIANA-miRPathv3.0 software was used for KEGG pathway and Gene Ontology analyses.
Overall 30 miRNAs were regulated by GH, 27 were up-regulated, and 3 down-regulated. A subset of 8 showed the most stringent criteria. Interestingly, 13 miRNAs were specifically regulated in females only and other 13 in males only, suggesting gender-specific effects.
In the entire population, the miRNAs identified, targeted genes involved in the following pathways: ExtraCellularMatrix-receptor (COL1A1,COL2A1,integrins,laminins,SOX9,NF1 genes,etc.), Thyroid hormone(THReceptor,ATP1B2,MAP2K2,PIK3R2,RAF1,NOTCH2,AKT,CASP9,STAT1,FOXO1,MAPK1,etc.), Steroid biosynthesis, mTOR signaling (BRAF,AKT,PIK3CD,IGF1,PTEN,etc.), MAPK signaling (BRAF,SOS2,FGFR3,RAF1,FGF4,EGFR,TGFB1,FGF11,AKT, FLNB,FGF9,NF1,TGFB2,FGFs,FGFRs,TGFB3,etc.), Prolactin signaling (PRLR,STAT3,SOS2,SHC1,RAF1,AKT2,JAK2,SOCS1,FOXO3,STAT1,SOCS7,etc.), PI3K-Akt signaling (FGFR3,FGFR4,COL4A5,IGF1R,EGFR,COL5A1,COL1A1, INSR,IGF1,VEGFB,FGFR1,FGF7,SOS2,RAF1,FGF8,etc.), Phosphatidylinositol signaling (PIK3R3,PTEN,etc.), and N-Glycan biosynthesis pathways.
Mutations of 15 of these genes are well known to cause genetic short stature in humans.
Furthermore, analyses of the biological processes identified the following as being regulated by the miRNAs identified: fibroblast growth factor receptor signaling, glycosaminoglycan metabolism, phosphatidylinositol-mediated signaling (FGFR3,IGF1R,PTPN11,IGF1,FGF8,FGFR1,etc.), insulin receptor signaling, transforming growth factor beta receptor signaling, androgen receptor signaling and the JAK-STAT cascade involved in GH signaling as expected.
In conclusion, GH regulates miRNAs that in turn regulate genes, pathways and biological processes involved with growth. Novel gender specific effects of GH were found. MiRNAs could be explored as biomarkers of response to treatment. Further, some novel genes implicated in the regulation of growth could be identified using this approach.
19 - 21 Sep 2019
European Society for Paediatric Endocrinology