RNA N6-甲基腺苷甲基转移酶 METTL3 通过激活 mA-GLUT1-mTORC1 轴促进结直肠癌发生，是一个治疗靶点。
RNA N-Methyladenosine Methyltransferase METTL3 Facilitates Colorectal Cancer by Activating the mA-GLUT1-mTORC1 Axis and Is a Therapeutic Target.
机构信息
Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong.
State Key Laboratory of Cellular Stress Biology and School of Life Sciences, Xiamen University, Xiamen, China.
出版信息
Gastroenterology. 2021 Mar;160(4):1284-1300.e16. doi: 10.1053/j.gastro.2020.11.013. Epub 2020 Nov 18.
BACKGROUND & AIMS: RNA N-methyladenosine (mA) modification has recently emerged as a new regulatory mechanism in cancer progression. We aimed to explore the role of the mA regulatory enzyme METTL3 in colorectal cancer (CRC) pathogenesis and its potential as a therapeutic target.
METHODS
The expression and clinical implication of METTL3 were investigated in multiple human CRC cohorts. The underlying mechanisms of METTL3 in CRC were investigated by integrative mA sequencing, RNA sequencing, and ribosome profiling analyses. The efficacy of targeting METTL3 in CRC treatment was elucidated in CRC cell lines, patient-derived CRC organoids, and Mettl3-knockout mouse models.
RESULTS
Using targeted clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 dropout screening, we identified METTL3 as the top essential mA regulatory enzyme in CRC. METTL3 was overexpressed in 62.2% (79/127) and 88.0% (44/50) of primary CRCs from 2 independent cohorts. High METTL3 expression predicted poor survival in patients with CRC (n = 374, P < .01). Functionally, silencing METTL3 suppressed tumorigenesis in CRC cells, human-derived primary CRC organoids, and Mettl3-knockout mouse models. We discovered the novel functional mA methyltransferase domain of METTL3 in CRC cells by domain-focused CRISPR screening and mutagenesis assays. Mechanistically, METTL3 directly induced the mA-GLUT1-mTORC1 axis as identified by integrated mA sequencing, RNA sequencing, ribosome sequencing, and functional validation. METTL3 induced GLUT1 translation in an mA-dependent manner, which subsequently promoted glucose uptake and lactate production, leading to the activation of mTORC1 signaling and CRC development. Furthermore, inhibition of mTORC1 potentiated the anticancer effect of METTL3 silencing in CRC patient-derived organoids and METTL3 transgenic mouse models.
CONCLUSIONS
METTL3 promotes CRC by activating the mA-GLUT1-mTORC1 axis. METTL3 is a promising therapeutic target for the treatment of CRC.
背景与目的
RNA N6-甲基腺苷（m6A）修饰最近成为癌症进展中的一种新的调控机制。我们旨在探索 m6A 调控酶 METTL3 在结直肠癌（CRC）发病机制中的作用及其作为治疗靶点的潜力。
方法
在多个人类 CRC 队列中研究了 METTL3 的表达和临床意义。通过整合 m6A 测序、RNA 测序和核糖体谱分析，研究了 METTL3 在 CRC 中的潜在机制。在 CRC 细胞系、患者来源的 CRC 类器官和 Mettl3 敲除小鼠模型中阐明了靶向 METTL3 治疗 CRC 的疗效。
结果
使用靶向簇状规则间隔短回文重复（CRISPR）/Cas9 缺失筛选，我们确定 METTL3 是 CRC 中最重要的 m6A 调控酶。在 2 个独立队列的 62.2%（79/127）和 88.0%（44/50）的原发性 CRC 中，METTL3 过表达。高 METTL3 表达预示着 CRC 患者预后不良（n=374，P<.01）。功能上，沉默 METTL3 抑制了 CRC 细胞、人类来源的原发性 CRC 类器官和 Mettl3 敲除小鼠模型中的肿瘤发生。通过域聚焦 CRISPR 筛选和诱变实验，我们在 CRC 细胞中发现了 METTL3 的新型功能性 m6A 甲基转移酶结构域。在机制上，通过整合 m6A 测序、RNA 测序、核糖体测序和功能验证，我们发现 METTL3 直接诱导了 mA-GLUT1-mTORC1 轴。METTL3 以 mA 依赖性方式诱导 GLUT1 翻译，随后促进葡萄糖摄取和乳酸生成，导致 mTORC1 信号激活和 CRC 发展。此外，在 CRC 患者来源的类器官和 METTL3 转基因小鼠模型中，抑制 mTORC1 增强了 METTL3 沉默的抗癌作用。
结论
METTL3 通过激活 mA-GLUT1-mTORC1 轴促进 CRC。METTL3 是治疗 CRC 的有前途的治疗靶点。
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