miR-20b-3p regulates bone healing via GFI1

Abstract

Background and study aims: As severe intra-articular injuries of the distal tibia, Pilon fractures are frequently complicated by delayed bone consolidation and nonunion. Early prediction of healing outcomes remains challenging due to the lack of reliable molecular markers. This study aimed to determine the diagnostic utility of serum miR-20b-3p for Pilon fracture consolidation and to elucidate its mechanistic role in modulating osteoblast activity via GFI1.

Materials and methods: The clinical cohort comprised 183 individuals treated for closed, unilateral Pilon fractures. Circulating miR-20b-3p was quantified using qRT-PCR, with its diagnostic capacity evaluated using receiver operating characteristic (ROC) curves. Mechanistically, a dual-luciferase reporter system confirmed the direct targeting of GFI1 by miR-20b-3p. For in vitro analyses, MC3T3-E1 pre-osteoblasts were transfected with specific miR-20b-3p mimics or inhibitors. Subsequently, cellular proliferation and osteogenic marker transcripts were evaluated utilizing CCK-8 assays and qRT-PCR, respectively.

Results: Circulating miR-20b-3p was significantly reduced among patients who failed to heal normally (P < 0.001). ROC analysis revealed that miR-20b-3p had good diagnostic performance for predicting delayed union, with an AUC of 0.890. GFI1 was identified as a direct target of miR-20b-3p. In vitro, overexpression of miR-20b-3p significantly promoted MC3T3-E1 cell proliferation and upregulated osteogenic markers, whereas inhibition of miR-20b-3p exerted the opposite effect. The pro-osteogenic effects of miR-20b-3p were reversed by GFI1 overexpression.

Conclusions: miR-20b-3p may serve as a diagnostic biomarker for Pilon fracture healing and facilitate osteoblast proliferation and differentiation by targeting GFI1.