Darvishi Emad, Slemmons Katherine, Wan Zesheng, Mitra Sheetal, Hou Xiaogang, Parmentier Jean Hugues, Eddie Loh Yong-Hwee, Helman Lee J
Division of Hematology-Oncology, Cancer and Blood Disease Institute, Children's Hospital Los Angeles, Los Angeles, CA, USA.
USC Libraries Bioinformatics Services, Los Angeles, CA, USA.
Neoplasia. 2020 Jul;22(7):274-282. doi: 10.1016/j.neo.2020.05.001. Epub 2020 May 25.
Fibroblast growth factor receptor 4 (FGFR4) aberrant expression and activity have been linked to the pathogenesis of a variety of cancers including rhabdomyosarcomas (RMS). We found that treatment of alveolar rhabdomyosarcoma (aRMS) cells with Guadecitabine (SGI-110), a next-generation DNA methyltransferase inhibitor (DNMTi), resulted in a significant reduction of FGFR4 protein levels, 5 days post treatment. Chromatin immunoprecipitation-sequencing (ChIP-seq) in aRMS cells revealed attenuation of the H3K4 mono-methylation across the FGFR4 super enhancer without changes in tri-methylation of either H3K4 or H3K27. These changes were associated with a significant reduction in FGFR4 transcript levels in treated cells. These decreases in H3K4me1 in the FGFR4 super enhancer were also associated with a 240-fold increase in KDM5B (JARID1B) mRNA levels. Immunoblot and immunofluorescent studies also revealed a significant increase in the KDM5B protein levels after treatment in these cells. KDM5B is the only member of KDM5 (JARID1) family of histone lysine demethylases that catalyzes demethylation of H3K4me1. These data together suggest a pleiotropic effect of DNMTi therapy in aRMS cells, converging to significantly lower FGFR4 protein levels in these cells.
成纤维细胞生长因子受体4（FGFR4）的异常表达和活性与包括横纹肌肉瘤（RMS）在内的多种癌症的发病机制有关。我们发现，用新一代DNA甲基转移酶抑制剂（DNMTi）瓜地西他滨（SGI-110）处理肺泡横纹肌肉瘤（aRMS）细胞后5天，FGFR4蛋白水平显著降低。aRMS细胞中的染色质免疫沉淀测序（ChIP-seq）显示，FGFR4超级增强子上的H3K4单甲基化减弱，而H3K4或H3K27的三甲基化没有变化。这些变化与处理后细胞中FGFR4转录水平的显著降低有关。FGFR4超级增强子中H3K4me1的这些降低也与KDM5B（JARID1B）mRNA水平增加240倍有关。免疫印迹和免疫荧光研究还显示，处理后这些细胞中KDM5B蛋白水平显著增加。KDM5B是组蛋白赖氨酸去甲基化酶KDM5（JARID1）家族中唯一催化H3K4me1去甲基化的成员。这些数据共同表明DNMTi疗法对aRMS细胞具有多效性作用，最终显著降低这些细胞中的FGFR4蛋白水平。
