Renmin Hospital of Wuhan University, Wuhan, China.
PeerJ. 2022 May 3;10:e13319. doi: 10.7717/peerj.13319. eCollection 2022.
Steroid-induced osteonecrosis of the femoral head (SONFH) is a disorder that causes severe disability in patients and has a high incidence worldwide. Although glucocorticoid (GC)-induced apoptosis of osteoblasts is an important cytological basis of SONFH, the detailed mechanism underlying SONFH pathogenesis remains elusive. PI3K/AKT signaling pathway was reported to involve in cell survival and apoptosis.
We explored the role of PI3K/AKT/FOXO1 signaling pathway and its downstream targets during glucocorticoid -induced osteonecrosis of the femoral head.
We obtained gene expression profile of osteoblasts subjected to dexamethasone (Dex) treatment from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were screened out and functional enrichment analysis were conducted by bioinformatics analysis. , we analyzed Dex-induced apoptosis in MC3T3-E1 cells and explored the role of PI3K/AKT/FOXO1 signaling pathway in this phenomenon by employing siRNA-FOXO1 and IGF-1(PI3K/AKT agonist). Finally, we verified our results in a rat model of SONFH.
In Dex-treated osteoblasts, DEGs were mainly enriched in the FOXO signaling pathway. Dex inhibited MC3T3-E1 cell viability in a dose-dependent effect and induced apoptosis by increasing the expression levels of FOXO1, Bax, cleaved-Caspase-3, and cleaved-Caspase-9, while reducing the expression of Bcl-2. Notably, these results were reversed by siRNA-FOXO1 treatment. Dex inhibited PI3K/AKT signaling pathway, upregulated FOXO1 expression and increased FOXO1 nuclear translocation, which were reversed by IGF-1. Compared to normal rats, the femoral head of SONFH showed increased expression of FOXO1, increased number of apoptotic cells, and empty osteocytic lacunas, as well as decreased bone tissue content and femoral head integrity. Significantly, the effects of GC-induced SONFH were alleviated following IGF-1 treatment.
Dex induces osteoblast apoptosis via the PI3K/AKT/FOXO1 signaling pathway. Our research offers new insights into the underlying molecular mechanisms of glucocorticoid-induced osteonecrosis in SONFH and proposes FOXO1 as a therapeutic target for this disease.
激素诱导性股骨头坏死（SONFH）是一种导致患者严重残疾的疾病，在全球范围内发病率较高。虽然糖皮质激素（GC）诱导成骨细胞凋亡是 SONFH 的重要细胞学基础，但 SONFH 发病机制的详细机制仍不清楚。PI3K/AKT 信号通路被报道涉及细胞存活和凋亡。
我们探讨了 PI3K/AKT/FOXO1 信号通路及其下游靶标在糖皮质激素诱导性股骨头坏死中的作用。
我们从基因表达综合数据库（GEO）数据库中获得了成骨细胞接受地塞米松（Dex）处理后的基因表达谱。通过生物信息学分析筛选差异表达基因（DEGs）并进行功能富集分析。我们分析了 Dex 诱导的 MC3T3-E1 细胞凋亡，并通过 siRNA-FOXO1 和 IGF-1（PI3K/AKT 激动剂）探讨了 PI3K/AKT/FOXO1 信号通路在这一现象中的作用。最后，我们在 SONFH 大鼠模型中验证了我们的结果。
在 Dex 处理的成骨细胞中，DEGs 主要富集在 FOXO 信号通路中。Dex 呈剂量依赖性抑制 MC3T3-E1 细胞活力，并通过增加 FOXO1、Bax、cleaved-Caspase-3 和 cleaved-Caspase-9 的表达水平，同时降低 Bcl-2 的表达水平诱导细胞凋亡。值得注意的是，siRNA-FOXO1 处理可逆转这些结果。Dex 抑制 PI3K/AKT 信号通路，上调 FOXO1 表达并增加 FOXO1 核转位，IGF-1 可逆转这些作用。与正常大鼠相比，SONFH 大鼠的股骨头显示 FOXO1 表达增加、凋亡细胞数量增加、空骨陷窝增加，以及骨组织含量和股骨头完整性降低。值得注意的是，IGF-1 治疗后 GC 诱导的 SONFH 作用减轻。
Dex 通过 PI3K/AKT/FOXO1 信号通路诱导成骨细胞凋亡。我们的研究为 SONFH 中糖皮质激素诱导性骨坏死的潜在分子机制提供了新的见解，并提出 FOXO1 作为该疾病的治疗靶点。
