Nagai Yuzo, Sunami Eiji, Yamamoto Yoko, Hata Keisuke, Okada Satoshi, Murono Koji, Yasuda Koji, Otani Kensuke, Nishikawa Takeshi, Tanaka Toshiaki, Kiyomatsu Tomomichi, Kawai Kazushige, Nozawa Hiroaki, Ishihara Soichiro, Hoon Dave S B, Watanabe Toshiaki
Department of Surgical Oncology, Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
Department of Translational Molecular Medicine, Div. Molecular Oncology, John Wayne Cancer Institute, Saint John's Hospital and Health Center, Santa Monica, CA, USA.
Oncotarget. 2017 Feb 14;8(7):11906-11916. doi: 10.18632/oncotarget.14439.
Colorectal cancer (CRC) is a serious public health problem and non-invasive biomarkers improving diagnosis or therapy are strongly required. Circulating cell-free DNA (cfDNA) has been a promising target for this purpose. In this study, we evaluated the potential of long interspersed nuclear element-1 (LINE-1) hypomethylation as a blood biomarker for CRC. LINE-1 hypomethylation level in plasma cfDNA in 114 CRC patients was retrospectively examined by absolute quantitative analysis of methylated alleles real-time PCR, and was expressed using LINE-1 hypomethylation index (LHI) [unmethylated copy number/ (methylated copy number + unmethylated copy number)]. Greater LHI values indicated enhanced hypomethylation. In our clinicopathological analysis, CRC patients with large tumors (≥6.0 cm), advanced N stage (≥2), and distant metastasis (M1) had statistically significantly higher cfDNA LHI than other CRC patients, suggesting cfDNA LHI as a disease progression biomarker for CRC. Furthermore, early stage I/II (n = 57) as well as advanced stage III/IV (n =57) CRC patients had significantly higher cfDNA LHI than healthy donors (n=53) [stage I/II: median 0.369 (95% confidence interval, 0.360-0.380) vs. 0.332 (0.325-0.339), P < 0.0001; stage III/IV: 0.372 (0.365-0.388) vs. 0.332 (0.325-0.339), P < 0.0001]. The receiver operating characteristic analysis showed that cfDNA LHI had the detection capacity of CRC with area under the curve(AUC) of 0.79 and 0.83 in stage I/II and stage III/IV CRC patients, respectively. The present study demonstrated for the first time the potential of plasma cfDNA LHI as a novel biomarker for CRC, particularly for early stage detection.
结直肠癌（CRC）是一个严重的公共卫生问题，因此迫切需要能够改善诊断或治疗的非侵入性生物标志物。循环游离DNA（cfDNA）一直是实现这一目标的一个有前景的靶点。在本研究中，我们评估了长散在核元件1（LINE-1）低甲基化作为CRC血液生物标志物的潜力。通过甲基化等位基因实时PCR的绝对定量分析，回顾性检测了114例CRC患者血浆cfDNA中的LINE-1低甲基化水平，并使用LINE-1低甲基化指数（LHI）[未甲基化拷贝数/（甲基化拷贝数+未甲基化拷贝数）]来表示。LHI值越高表明低甲基化程度越高。在我们的临床病理分析中，肿瘤较大（≥6.0 cm）、N分期较晚（≥2）和远处转移（M1）的CRC患者的cfDNA LHI在统计学上显著高于其他CRC患者，这表明cfDNA LHI可作为CRC疾病进展的生物标志物。此外，早期I/II期（n = 57）以及晚期III/IV期（n = 57）的CRC患者的cfDNA LHI显著高于健康供者（n = 53）[I/II期：中位数0.369（95%置信区间，0.360 - 0.380）对0.332（0.325 - 0.339），P < 0.0001；III/IV期：0.372（0.365 - 0.388）对0.332（0.325 - 0.339），P < 0.0001]。受试者工作特征分析表明，cfDNA LHI在I/II期和III/IV期CRC患者中对CRC的检测能力分别为曲线下面积（AUC）0.79和0.83。本研究首次证明了血浆cfDNA LHI作为CRC新型生物标志物的潜力，特别是在早期检测方面。
