Quantitative Analysis of Methylated Adenosine Modifications Revealed Increased Levels of N 6-Methyladenosine (m6A) and N 6,2'- O-Dimethyladenosine (m6Am) in Serum From Colorectal Cancer and Gastric Cancer Patients

Yiqiu Hu; Zhihao Fang; Jiayi Mu; Yanqin Huang; Shu Zheng; Ying Yuan; Cheng Guo

doi:10.3389/fcell.2021.694673

Quantitative Analysis of Methylated Adenosine Modifications Revealed Increased Levels of N ⁶-Methyladenosine (m⁶A) and N ⁶,2'- O-Dimethyladenosine (m⁶Am) in Serum From Colorectal Cancer and Gastric Cancer Patients

Front Cell Dev Biol. 2021 Jul 26:9:694673. doi: 10.3389/fcell.2021.694673. eCollection 2021.

Authors

Yiqiu Hu¹, Zhihao Fang¹, Jiayi Mu¹, Yanqin Huang¹, Shu Zheng¹, Ying Yuan², Cheng Guo^{1

3}

Affiliations

¹ Cancer Institute (Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education), The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
² Department of Medical Oncology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
³ Cancer Center, Zhejiang University, Hangzhou, China.

Abstract

Colorectal cancer and gastric cancer are the most prevalent gastrointestinal malignancies worldwide, and early detection of these cancers is crucial to reduce their incidence and mortality. RNA methylation plays an important regulatory role in a variety of physiological activities, and it has drawn great attention in recent years. Methylated adenosine (A) modifications such as N ⁶-methyladenosine (m⁶A), N ¹-methyladenosine (m¹A), 2'-O-methyladenosine (Am), N ⁶,2'-O-dimethyladenosine (m⁶Am), and N ⁶,N ⁶-dimethyladenosine (m⁶ ₂A) are typical epigenetic markers of RNA, and they are closely correlated to various diseases including cancer. Serum is a valuable source of biofluid for biomarker discovery, and determination of these adenosine modifications in human serum is desirable since they are emerging biomarkers for detection of diseases. In this work, a targeted quantitative analysis method using hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) was developed and utilized to analyze these methylated adenosine modifications in serum samples. The concentration differences between the healthy volunteers and cancer patients were evaluated by Mann-Whitney test, and receiver operator characteristic (ROC) curve analysis was performed to access the potential of these nucleosides as biomarkers. We demonstrated the presence of the m⁶Am in human serum for the first time, and we successfully quantified the concentrations of A, m⁶A, m¹A, and m⁶Am in serum samples from 99 healthy controls, 51 colorectal cancer patients, and 27 gastric cancer patients. We found that the levels of m⁶A and m⁶Am in serum were both increased in colorectal cancer or gastric cancer patients, compared to that in healthy controls. These results indicate that m⁶A and m⁶Am in serum may act as potential biomarkers for early detection and prognosis of colorectal cancer and gastric cancer. In addition, the present work will stimulate investigations on the effects of adenosine methylation on the initiation and progression of colorectal cancer and gastric cancer.

Keywords: RNA methylation; biomarker; colorectal cancer; gastric cancer; hydrophilic interaction liquid chromatography-tandem mass spectrometry; methylated adenosine.