Chen Xun, Zhang Qian, Dang Xiaoqian, Fan Jinzhu, Song Tao, Li Zhong, Duan Ning, Zhang Wentao
Department of Orthopaedics, Honghui Hospital, Xi'an Jiaotong University, 76 Nanguo Rd, Beilin District, Xi'an, Shaanxi 710054, China; Department of Orthopaedics, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710005, China.
The Department of Surgery Room, Xi'an Daxing Hospital, Xi'an, Shaanxi 710016, China.
Transl Oncol. 2022 Jul;21:101429. doi: 10.1016/j.tranon.2022.101429. Epub 2022 Apr 19.
Most tumors, including osteosarcomas, have deficiencies in DNA damage repair. However, the regulatory mechanisms underlying dysregulation of DNA damage repair genes are still being investigated. In this study, we reveal that C-terminal binding protein (CtBP) interacting protein (CtIP) couples with three transcriptional regulators, CtBP1/2 heterodimer, histone deacetylase 1 (HDAC1), and two subunits of the activating protein 1 (AP1) transcription factor to assemble a transcriptional complex. This complex specifically controls the expression of four genes involved in DNA damage and repair processes: MutL homolog 1 (MLH1), MutS Homolog 3 (MSH3), breast cancer type 1 (BRCA1), and cyclin dependent kinase inhibitor 1A (CDKN1A). Chromatin immunoprecipitation (ChIP) assay results revealed that the CtIP-CtBP1/2-HDAC1-AP1 complex regulated these four genes by binding to their promoters through the TGAT/CTCA consensus sequence. The depletion of CtIP, CtBP1/2, and HDAC1 increased the expression levels of MLH1, MSH3, BRCA1, and CDKN1A and inhibited in vitro and in vivo osteosarcoma cell growth. Overexpression of MLH1, MSH3, BRCA1, or CDKN1A in osteosarcoma cells can reduce cell viability, colony formation, cell migration, and tumor growth. Our findings suggest that the CtIP-CtBP1/2-HDAC1-AP1 complex is required for mediation of DNA damage processes for the pathogenesis of osteosarcoma.
大多数肿瘤，包括骨肉瘤，在DNA损伤修复方面存在缺陷。然而，DNA损伤修复基因失调背后的调控机制仍在研究中。在本研究中，我们发现C末端结合蛋白（CtBP）相互作用蛋白（CtIP）与三种转录调节因子，即CtBP1/2异二聚体、组蛋白去乙酰化酶1（HDAC1）以及激活蛋白1（AP1）转录因子的两个亚基结合，组装成一个转录复合物。该复合物特异性地控制参与DNA损伤和修复过程的四个基因的表达：错配修复蛋白MutL同源物1（MLH1）、错配修复蛋白MutS同源物3（MSH3）、乳腺癌1型（BRCA1）和细胞周期蛋白依赖性激酶抑制剂1A（CDKN1A）。染色质免疫沉淀（ChIP）分析结果显示，CtIP-CtBP1/2-HDAC1-AP1复合物通过TGAT/CTCA共有序列结合这四个基因的启动子来调控它们。CtIP、CtBP1/2和HDAC1的缺失增加了MLH1、MSH3、BRCA1和CDKN1A的表达水平，并抑制了体外和体内骨肉瘤细胞的生长。在骨肉瘤细胞中过表达MLH1、MSH3、BRCA1或CDKN1A可降低细胞活力、集落形成、细胞迁移和肿瘤生长。我们的研究结果表明，CtIP-CtBP1/2-HDAC1-AP1复合物是骨肉瘤发病机制中DNA损伤过程介导所必需的。
