Identification and validation of SQLE in steroid-induced osteonecrosis of the femoral head: a bioinformatics and experimental study

Background: Osteonecrosis of the femoral head (ONFH) is a prevalent and refractory hip disease. In this study, we investigated the expression profiles of lipid metabolism-related genes in ONFH and evaluated the potential therapeutic effects of squalene epoxidase (SQLE) and its inhibitors.

Methods: Dexamethasone was used to establish an in vitro ONFH model in MC3T3-E1 cells. Differentially expressed genes (DEGs) in the model group were identified through transcriptome Sequencing. Lipid metabolism-related DEGs were extracted from GeneCards, and hub genes were determined via a protein-protein interaction (PPI) network. The expression patterns and diagnostic value of these hub genes were further validated using the GEO dataset. qRT-PCR and WB were performed to detect the expression of hub genes. Subsequently, the effects of SQLE knockdown and overexpression on osteoblast proliferation, Apoptosis, and osteogenic differentiation were further evaluated. The involvement of Ferroptosis was assessed by measuring Fe²⁺, ROS, MDA and GSH levels, with or without the Ferroptosis inhibitor Fer-1. An in vivo rat model of ONFH was established. The therapeutic effects of SQLE inhibitors were evaluated by micro-CT, H&E staining, immunohistochemistry, serum lipid profiles, and ferroptosis-related indices.

Results: A total of 579 DEGs were identified, and these DEGs were enriched in various functions and pathways. After constructing the PPI network, five hub genes (Fdps, Lss, Sqle, Nsdhl, and Hmgcs2) were identified. GEO dataset validation confirmed consistent expression trends and diagnostic value for these genes. In vitro, SQLE knockdown significantly alleviated MC3T3-E1 damage, and mitigated ferroptosis-related oxidative stress. Conversely, SQLE overexpression aggravated these effects. In vivo, terbinafine treatment improved bone microarchitecture, reduced empty lacunae, normalized serum lipid profiles, and suppressed Ferroptosis markers in ONFH rats.

Conclusions: This study reveals the role of SQLE in ONFH. Targeting SQLE, either through genetic silencing or pharmacological inhibition, alleviates osteoblast dysfunction and bone loss, providing a potential therapeutic strategy for ONFH.

Bioinformatics; Lipid metabolism; Osteonecrosis of the femoral head; Squalene epoxidase; Terbinafine; Transcriptome sequencing.