Department of Colorectal Surgery, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China.
Guangdong Institute of Gastroenterology, Guangzhou, Guangdong, China.
Clin Transl Med. 2023 May;13(5):e1279. doi: 10.1002/ctm2.1279.
N6-methyladenosine (m6A) modification is an emerging epigenetic regulatory mechanism in tumourigenesis. Considering that AlkB homolog 5 (ALKBH5) is a well-described m6A demethylase in previous enzyme assays, we aimed to investigate the role of m6A methylation alteration conferred by disturbed ALKBH5 in colorectal cancer (CRC) development.
Expression of ALKBH5 and its correlation with clinicopathological characteristics of CRC were evaluated using the prospectively maintained institutional database. The molecular role and underlying mechanism of ALKBH5 in CRC were explored using in vitro and in vivo experiments with methylated RNA immunoprecipitation sequencing (MeRIP-seq), RNA-seq, MeRIP-qPCR, RIP-qPCR and luciferase reporter assays.
ALKBH5 expression was significantly upregulated in CRC tissues compared to the paired adjacent normal tissues, and higher expression of ALKBH5 was independently associated with worse overall survival in CRC patients. Functionally, ALKBH5 promoted the proliferative, migrative and invasive abilities of CRC cells in vitro and enhanced subcutaneous tumour growth in vivo. Mechanistically, RAB5A was identified as the downstream target of ALKBH5 in CRC development, and ALKBH5 posttranscriptionally activated RAB5A by m6A demethylation, which impeded the YTHDF2-mediated degradation of RAB5A mRNA. In addition, we demonstrated that dysregulation of the ALKBH5-RAB5A axis could affect the tumourigenicity of CRC.
ALKBH5 facilitates the progression of CRC by augmenting the expression of RAB5A via an m6A-YTHDF2-dependent manner. Our findings suggested that ALKBH5-RAB5A axis might serve as valuable biomarkers and effective therapeutic targets for CRC.
N6-甲基腺嘌呤（m6A）修饰是肿瘤发生中新兴的表观遗传调控机制。考虑到 AlkB 同源物 5（ALKBH5）在之前的酶实验中是一种描述很好的 m6A 去甲基酶，我们旨在研究由 ALKBH5 紊乱引起的 m6A 甲基化改变在结直肠癌（CRC）发展中的作用。
使用前瞻性维护的机构数据库评估 ALKBH5 的表达及其与 CRC 临床病理特征的相关性。使用体外和体内实验，包括甲基化 RNA 免疫沉淀测序（MeRIP-seq）、RNA-seq、MeRIP-qPCR、RIP-qPCR 和荧光素酶报告基因测定，探索 ALKBH5 在 CRC 中的分子作用和潜在机制。
与配对的相邻正常组织相比，CRC 组织中 ALKBH5 的表达明显上调，并且 ALKBH5 的高表达与 CRC 患者的总生存时间独立相关。功能上，ALKBH5 促进 CRC 细胞在体外的增殖、迁移和侵袭能力，并增强体内皮下肿瘤生长。在机制上，RAB5A 被鉴定为 ALKBH5 在 CRC 发展中的下游靶标，ALKBH5 通过 m6A 去甲基化在后转录水平激活 RAB5A，从而阻碍了 YTHDF2 介导的 RAB5A mRNA 降解。此外，我们证明了 ALKBH5-RAB5A 轴的失调可以影响 CRC 的致瘤性。
ALKBH5 通过 m6A-YTHDF2 依赖的方式增强 RAB5A 的表达，促进 CRC 的进展。我们的研究结果表明，ALKBH5-RAB5A 轴可能作为 CRC 的有价值的生物标志物和有效的治疗靶点。
