Chuang Shu-Chun, Chou Ya-Shuan, Lin Yi-Shan, Chang Je-Ken, Chen Chung-Hwan, Ho Mei-Ling
Orthopaedic Research Center, Kaohsiung Medical University, Kaohsiung, Taiwan.
Regenerative Medicine and Cell Therapy Research Center, Kaohsiung Medical University, Kaohsiung, Taiwan.
Bone Joint Res. 2025 May 8;14(5):407-419. doi: 10.1302/2046-3758.145.BJR-2024-0262.R2.
Cyclooxygenase-2 (COX-2) is an enzyme that synthesizes prostaglandins from arachidonic acid. Previous reports have indicated that COX-2 is constitutively expressed in osteogenic cells instead of being expressed only after pathogenic induction, and that it facilitates osteoblast proliferation via PTEN/Akt/p27 signalling. However, the role of COX-2 in osteogenic differentiation of murine bone marrow mesenchymal stromal cells (BMSCs) remains controversial. In this study, we investigated the function of COX-2 in the osteogenic differentiation of BMSCs.
COX-2 inhibitor, COX-2 overexpression vector, and p27 small interfering RNA (siRNA) were used to evaluate the role of COX-2 in osteogenic differentiation and related signalling pathways in BMSCs.
We found that the messenger RNA (mRNA) and protein levels of COX-2 decreased gradually during osteogenic differentiation. Inhibition of COX-2 activity promoted FOXO3a and p27 expression and simultaneously enhanced osteogenesis, as indicated by increased osteogenic gene expression and mineralization in BMSCs. Furthermore, when p27 was silenced, the suppressive effects of COX-2 on osteogenesis were reversed. It demonstrated that the negative regulatory effect of COX-2 on osteogenesis was mediated by p27. In addition, our results showed that overexpression of COX-2 reduced the mRNA and protein levels of FOXO3a and p27, and thus attenuated osteogenic gene expression. These results indicate that COX-2 negatively regulates osteogenic differentiation by reducing the expression of osteogenic genes via the FOXO3a/p27 signalling pathway.
Together with the findings from previous and current studies, these results indicate that COX-2 has a different role in proliferation versus differentiation during osteogenesis via FOXO3a/p27 signalling in osteoblasts or BMSCs.
环氧化酶-2（COX-2）是一种将花生四烯酸合成为前列腺素的酶。先前的报道表明，COX-2在成骨细胞中组成性表达，而非仅在致病诱导后表达，并且它通过PTEN/Akt/p27信号通路促进成骨细胞增殖。然而，COX-2在小鼠骨髓间充质基质细胞（BMSCs）成骨分化中的作用仍存在争议。在本研究中，我们调查了COX-2在BMSCs成骨分化中的功能。
使用COX-2抑制剂、COX-2过表达载体和p27小干扰RNA（siRNA）来评估COX-2在BMSCs成骨分化及相关信号通路中的作用。
我们发现，在成骨分化过程中，COX-2的信使核糖核酸（mRNA）和蛋白质水平逐渐降低。抑制COX-2活性可促进FOXO3a和p27表达，同时增强成骨作用，这表现为BMSCs中成骨基因表达增加和矿化增强。此外，当p27沉默时，COX-2对成骨的抑制作用被逆转。这表明COX-2对成骨的负调节作用是由p27介导的。此外，我们的结果表明，COX-2的过表达降低了FOXO3a和p27的mRNA和蛋白质水平，从而减弱了成骨基因表达。这些结果表明，COX-2通过FOXO3a/p27信号通路降低成骨基因的表达，从而对成骨分化起负调节作用。
结合之前和当前研究的结果，这些结果表明，通过成骨细胞或BMSCs中的FOXO3a/p27信号通路，COX-2在成骨过程中的增殖与分化中具有不同的作用。
