Lin Shujuan, Gu Simeng, Qian Sangni, Liu Yaxin, Sheng Jinghao, Li Qilong, Yang Jinhua, Ying Xiaojiang, Li Zhenjun, Tang Mengling, Wang Jianbing, Chen Kun, Jin Mingjuan
Department of Epidemiology and Biostatistics at School of Public Health and the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
Department of Environmental Health, Institute of Endemic Diseases, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China.
Front Oncol. 2022 Jan 20;11:782077. doi: 10.3389/fonc.2021.782077. eCollection 2021.
Sporadic colorectal cancer (CRC) develops principally through the adenoma-carcinoma sequence. Previous studies revealed that DNA methylation alterations play a significant role in colorectal neoplastic transformation. On the other hand, long noncoding RNAs (lncRNAs) have been identified to be associated with some critical tumorigenic processes of CRC. Accumulating evidence indicates more intricate regulatory relationships between DNA methylation and lncRNAs in CRC. Nevertheless, the methylation alterations of lncRNAs at different stages of colorectal carcinogenesis based on a genome-wide scale remain elusive. Therefore, in this study, we first used an Illumina MethylationEPIC BeadChip (850K array) to identify the methylation status of lncRNAs in 12 pairs of colorectal cancerous and adjacent normal tissues from cohort I, followed by cross-validation with The Cancer Genome Atlas (TCGA) database and the Gene Expression Omnibus (GEO) database. Then, the abnormal hypermethylation of candidate genes in colorectal lesions was successfully confirmed by MassARRAY EpiTYPER in cohort II including 48 CRC patients, and cohort III including 286 CRC patients, 81 advanced adenoma (AA) patients and 81 nonadvanced adenoma (NAA) patients. hypermethylation was detected at all stages of colorectal neoplasms and occurred as early as the NAA stage during colorectal neoplastic progression. The methylation levels were significantly higher in the comparisons of CRC vs. NAA ( < 0.001) and AA vs. NAA ( = 0.004). Moreover, the hypermethylation of promoter was also found in cell-free DNA samples collected from CRC patients as compared to healthy controls ( = 0.003). Multivariate Cox proportional hazards regression analysis revealed promoter hypermethylation was independently associated with poorer disease-specific survival (HR = 2.52, 95% CI: 1.35-4.69, = 0.004) and overall survival (HR = 1.64, 95% CI: 1.02-2.64, = 0.042) in CRC patients. Finally, a nomogram was constructed and verified by a calibration curve to predict the survival probability of individual CRC patients (C-index: 0.789). Our findings indicate hypermethylation might be an early event during colorectal carcinogenesis and has the potential to be a novel biomarker for CRC progression and prognosis.
散发性结直肠癌（CRC）主要通过腺瘤-癌序列发展而来。先前的研究表明，DNA甲基化改变在结直肠肿瘤转化中起重要作用。另一方面，长链非编码RNA（lncRNAs）已被确定与CRC的一些关键致癌过程相关。越来越多的证据表明，CRC中DNA甲基化与lncRNAs之间存在更复杂的调控关系。然而，基于全基因组规模的结直肠癌发生不同阶段lncRNAs的甲基化改变仍不清楚。因此，在本研究中，我们首先使用Illumina MethylationEPIC BeadChip（850K芯片）来鉴定队列I中12对结直肠癌组织和相邻正常组织中lncRNAs的甲基化状态，随后通过癌症基因组图谱（TCGA）数据库和基因表达综合数据库（GEO）进行交叉验证。然后，在包括48例CRC患者的队列II以及包括286例CRC患者、81例高级别腺瘤（AA）患者和81例非高级别腺瘤（NAA）患者的队列III中，通过MassARRAY EpiTYPER成功证实了结直肠病变中候选基因的异常高甲基化。在结直肠肿瘤的所有阶段均检测到高甲基化，并且在结直肠肿瘤进展过程中最早在NAA阶段就出现了。在CRC与NAA的比较中（<0.001）以及AA与NAA的比较中（=0.004），甲基化水平显著更高。此外，与健康对照相比，在从CRC患者收集的游离DNA样本中也发现了启动子的高甲基化（=0.003）。多变量Cox比例风险回归分析显示，启动子高甲基化与CRC患者较差的疾病特异性生存（HR = 2.52，95%CI：1.35 - 4.69，= 0.004）和总生存（HR = 1.64，95%CI：1.02 - 2.64，= 0.042）独立相关。最后，构建了列线图并通过校准曲线进行验证，以预测个体CRC患者的生存概率（C指数：0.789）。我们的研究结果表明，高甲基化可能是结直肠癌发生过程中的早期事件，并且有可能成为CRC进展和预后评估的新型生物标志物。
