Department of Hematology, Shanghai Tenth People's Hospital, Tongji University Cancer Center, Tongji University School of Medicine, 200072, Shanghai, China.
Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA, USA.
Cell Death Dis. 2019 Aug 19;10(9):624. doi: 10.1038/s41419-019-1854-0.
Recent findings demonstrate that aberrant downregulation of the iron-exporter protein, ferroportin (FPN1), is associated with poor prognosis and osteoclast differentiation in multiple myeloma (MM). Here, we show that FPN1 was downregulated in MM and that clustered regularly interspaced short palindromic repeat (CRISPR)-mediated FPN1 knockout promoted MM cell growth and survival. Using a microRNA target-scan algorithm, we identified miR-17-5p as an FPN1 regulator that promoted cell proliferation and cell cycle progression, and inhibited apoptosis-both in vitro and in vivo. miR-17-5p inhibited retarded tumor growth in a MM xenograft model. Moreover, restoring FPN1 expression at least partially abrogated the biological effects of miR-17-5p in MM cells. The cellular iron concentration regulated the expression of the iron-regulatory protein (IRP) via the 5'-untranslated region of IRP messenger RNA and modulated the post-transcriptional stability of FPN1. Bioinformatics analysis with subsequent chromatin immunoprecipitation-polymerase chain reaction and luciferase activity experiments revealed that the transcription factor Nrf2 drove FPN1 transcription through promoter binding and suppressed miR-17-5p (which also increased FPN1 expression). Nrf2-mediated FPN1 downregulation promoted intracellular iron accumulation and reactive oxygen species. Our study links FPN1 transcriptional and post-transcriptional regulation with MM cell growth and survival, and validates the prognostic value of FPN1 and its utility as a novel therapeutic target in MM.
最近的研究结果表明，铁输出蛋白 Ferroportin （FPN1）的异常下调与多发性骨髓瘤（MM）的不良预后和破骨细胞分化有关。在这里，我们表明 FPN1 在 MM 中下调，并且簇状规则间隔短回文重复（CRISPR）介导的 FPN1 敲除促进了 MM 细胞的生长和存活。使用 microRNA 靶标扫描算法，我们鉴定出 miR-17-5p 是 FPN1 的调节剂，可促进细胞增殖和细胞周期进程，并在体外和体内抑制细胞凋亡。miR-17-5p 抑制了 MM 异种移植模型中的肿瘤生长。此外，至少部分恢复 FPN1 的表达可部分阻断 miR-17-5p 在 MM 细胞中的生物学作用。细胞内铁浓度通过铁调节蛋白（IRP）信使 RNA 的 5'-非翻译区调节 IRP 的表达，并调节 FPN1 的转录后稳定性。生物信息学分析随后进行染色质免疫沉淀聚合酶链反应和荧光素酶活性实验表明，转录因子 Nrf2 通过启动子结合驱动 FPN1 转录，并抑制 miR-17-5p（这也增加了 FPN1 的表达）。Nrf2 介导的 FPN1 下调促进了细胞内铁积累和活性氧的产生。我们的研究将 FPN1 的转录和转录后调节与 MM 细胞的生长和存活联系起来，并验证了 FPN1 的预后价值及其作为 MM 中新型治疗靶点的实用性。
