Department of Rheumatology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
Rheumatology (Oxford). 2022 Aug 3;61(8):3427-3438. doi: 10.1093/rheumatology/keab874.
Targeting synovial fibroblasts (SF) using a cyclin-dependent kinase (CDK) 4/6 inhibitor (CDKI) could be a potent therapy for RA via inhibition of proliferation and MMP-3 production. This study was designed to elucidate the mechanism of chondroprotective effects on SFs by CDK 4/6 inhibition.
CDK4/6 activity was inhibited using CDKI treatment or enhanced by adenoviral gene transduction. Chondroprotective effects were evaluated using a collagen-induced arthritis model (CIA). Gene and protein expression were evaluated with quantitative PCR, ELISA and Western blotting. The binding of nuclear extracts to DNA was assessed with an electrophoresis mobility shift assay. RNA-Seq was performed to identify gene sets affected by CDKI treatment.
CDKI attenuated cartilage destruction and MMP-3 production in CIA. In RASFs, CDKI impaired the binding of AP-1 components to DNA and inhibited the production of MMP-1 and MMP-3, which contain the AP-1 binding sequence in their promoter. CDK4/6 protected JUN from proteasome-dependent degradation by inhibiting ubiquitination. The RNA-Seq analysis identified CDKI-sensitive inflammatory genes, which were associated with the pathway of RA-associated genes, cytokine-cytokine receptor interaction and IL-17 signalling. Notably, the AP-1 motif was enriched in these genes.
The mechanism of chondroprotective effects by CDK4/6 inhibition was achieved by the attenuation of AP-1 transcriptional activity via the impaired stability of JUN. Because the pharmacologic inhibition of CDK4/6 has been established as tolerable in cancer treatment, it could also be beneficial in patients with RA due to its chondroprotective and anti-inflammatory effects.
通过抑制细胞周期蛋白依赖性激酶（CDK）4/6 的活性来靶向滑膜成纤维细胞（SF），可能是通过抑制增殖和 MMP-3 产生来治疗类风湿关节炎（RA）的有效方法。本研究旨在阐明 CDK4/6 抑制对 SF 产生软骨保护作用的机制。
使用 CDKI 治疗或腺病毒基因转导来抑制 CDK4/6 活性。使用胶原诱导性关节炎模型（CIA）评估软骨保护作用。采用定量 PCR、ELISA 和 Western blot 评估基因和蛋白表达。通过电泳迁移率变动分析评估核提取物与 DNA 的结合。采用 RNA-Seq 鉴定受 CDKI 治疗影响的基因集。
CDKI 可减轻 CIA 中的软骨破坏和 MMP-3 产生。在 RA-SFs 中，CDKI 可削弱 AP-1 成分与 DNA 的结合，并抑制 MMP-1 和 MMP-3 的产生，这些酶的启动子中含有 AP-1 结合序列。CDK4/6 通过抑制泛素化来阻止蛋白酶体对 JUN 的降解。RNA-Seq 分析鉴定出 CDKI 敏感的炎症基因，这些基因与 RA 相关基因、细胞因子-细胞因子受体相互作用和 IL-17 信号通路有关。值得注意的是，AP-1 基序在这些基因中富集。
CDK4/6 抑制的软骨保护作用机制是通过削弱 JUN 的稳定性来抑制 AP-1 转录活性来实现的。由于 CDK4/6 的药理学抑制已被确立为癌症治疗中的可耐受方法，由于其具有软骨保护和抗炎作用，因此也可能对 RA 患者有益。
