Sang Lina, Wu Xia, Yan Tianyou, Naren Duolan, Liu Xiaoyan, Zheng Xue, Zhang Nanchen, Wang Huifang, Li Yarong, Gong Yuping
Department of Hematology, West China Hospital, Sichuan University, China, 610041.
J Cancer. 2022 Jan 4;13(3):1019-1030. doi: 10.7150/jca.60381. eCollection 2022.
N6-methyladenosine (mA) is the most abundant internal modification in mammalian mRNA and recent studies have highlighted the importance of mA levels in tumor development. In this study, we investigated the expression of methyltransferase-like 3 (METTL3) and 14 (METTL14), components of the RNA mA methyltransferase complex, in samples from 89 patients with acute myeloid leukemia (AML), and followed the survival of 75 of these patients. Our results show that METTL3 and METTL14 are highly expressed in most of the patients with AML (except those with APL), and high levels of METTL3 and/or METTL14 correlated to shorter survival in the patients. In leukemia cell lines K562 and kasumi-1, both METTL3 and METTL14 promote cell proliferation and cell cycle, and the knockdown of METTL3 and METTL14 inhibits proliferation, and induces apoptosis and differentiation. Notably, the knockdown of METTL3 and METTL14 in K562 cell line leads to several changes in the expression of p53 signal pathway, including the upregulation of p53, cyclin dependent kinase inhibitor 1A (/), and downregulation of mdm2. Importantly, the mA level of mdm2 mRNA was significant lower after knock-down of METTL3 and METTL14 examined by mA-RIP and mdm2 qPCR assay, and the half-life of mdm2 under actinomycin-D treatment became shorter. Taken together, our study demonstrates that the lower mA levels of mdm2 mRNA mediated by the knockdown of METTL3 and METTL14 could lead to the low stability of mdm2 mRNA transcripts and low expression of MDM2, in the end, activate p53 signal pathway. Both METTL3 and METTL14 play an oncogenic role in AML by targeting mdm2/p53 signal pathway.
N6-甲基腺苷（mA）是哺乳动物mRNA中最丰富的内部修饰，最近的研究突出了mA水平在肿瘤发展中的重要性。在本研究中，我们调查了RNA mA甲基转移酶复合物的组成成分——甲基转移酶样3（METTL3）和14（METTL14）在89例急性髓系白血病（AML）患者样本中的表达情况，并对其中75例患者进行了生存随访。我们的结果显示，METTL3和METTL14在大多数AML患者（除急性早幼粒细胞白血病患者外）中高表达，METTL3和/或METTL14的高水平与患者较短的生存期相关。在白血病细胞系K562和kasumi-1中，METTL3和METTL14均促进细胞增殖和细胞周期进程，而敲低METTL3和METTL14则抑制增殖，并诱导细胞凋亡和分化。值得注意的是，在K562细胞系中敲低METTL3和METTL14会导致p53信号通路表达发生若干变化，包括p53、细胞周期蛋白依赖性激酶抑制剂1A（/）上调以及mdm2下调。重要的是，通过mA-RIP和mdm2 qPCR检测发现，敲低METTL3和METTL14后，mdm2 mRNA的mA水平显著降低，并且在放线菌素-D处理下mdm2的半衰期变短。综上所述，我们的研究表明，敲低METTL3和METTL14介导的mdm2 mRNA较低的mA水平可导致mdm2 mRNA转录本稳定性降低和MDM2表达下调，最终激活p53信号通路。METTL3和METTL14均通过靶向mdm2/p53信号通路在AML中发挥致癌作用。
