Mesenchymal stem cells (MSCs) have been shown to be involved in bone injury repair. Programmed cell death 4 (PDCD4) is not only a tumor suppressor gene but also plays roles in the regulation of MSC function. The aim of the study was to uncover PDCD4 potential regulatory roles and mechanisms in the osteogenic differentiation and bone defect repair of MSCs. shRNA technique was used to knock down PDCD4 expression in umbilical cord-derived mesenchymal stem cells (shPDCD4-UCMSCs). Their phenotype was characterized by flow cytometry and the differentiation potential was verified. We found that PDCD4 knockdown did not affect the surface molecule expression of UCMSCs, but significantly enhanced their osteogenic differentiation and osteogenesis-related molecule expression. Mechanistically, glycogen synthase kinase-3β (GSK-3β) phosphorylation and β-catenin expression were significantly increased in shPDCD4-UCMSCs during the osteogenic differentiation process. The β-catenin inhibitor PNU-74654 reversed shPDCD4-increased osteogenesis and osteogenesis-related molecule expression. The results of animal experiments showed that shPDCD4-UCMSCs markedly improved the defect healing in rabbits. Our findings suggest that PDCD4 acts as a negative regulator of MSC osteogenic differentiation through GSK-3β/β-catenin pathway. Targeting PDCD4 may be a way to improve MSC-mediated therapeutic effects on bone injury.

中文翻译：

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PDCD4 通过 GSK-3β/β-Catenin 通路负调控间充质干细胞的成骨分化和骨缺损修复

间充质干细胞 (MSCs) 已被证明参与骨损伤修复。程序性细胞死亡 4 (PDCD4) 不仅是肿瘤抑制基因，而且在调节 MSC 功能中发挥作用。该研究的目的是揭示 PDCD4 在 MSCs 成骨分化和骨缺损修复中的潜在调节作用和机制。shRNA技术用于敲低脐带间充质干细胞（shPDCD4-UCMSCs）中PDCD4的表达。它们的表型通过流式细胞术进行表征，并验证了分化潜力。我们发现 PDCD4 敲低不影响 UCMSCs 的表面分子表达，但显着增强了其成骨分化和成骨相关分子的表达。机械地，在成骨分化过程中，shPDCD4-UCMSCs 中的糖原合酶激酶-3β (GSK-3β) 磷酸化和 β-连环蛋白表达显着增加。β-连环蛋白抑制剂 PNU-74654 逆转了 shPDCD4 增加的成骨和成骨相关分子的表达。动物实验结果表明，shPDCD4-UCMSCs显着改善了兔的缺损愈合。我们的研究结果表明，PDCD4 通过 GSK-3β/β-catenin 通路作为 MSC 成骨分化的负调节因子。靶向 PDCD4 可能是改善 MSC 介导的骨损伤治疗效果的一种方法。动物实验结果表明，shPDCD4-UCMSCs显着改善了兔的缺损愈合。我们的研究结果表明，PDCD4 通过 GSK-3β/β-catenin 通路作为 MSC 成骨分化的负调节因子。靶向 PDCD4 可能是改善 MSC 介导的骨损伤治疗效果的一种方法。动物实验结果表明，shPDCD4-UCMSCs显着改善了兔的缺损愈合。我们的研究结果表明，PDCD4 通过 GSK-3β/β-catenin 通路作为 MSC 成骨分化的负调节因子。靶向 PDCD4 可能是改善 MSC 介导的骨损伤治疗效果的一种方法。