Quantification of ultra-rare somatic mutations using molecular barcode and risk assessment of cancer

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K07155
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Tumor diagnostics
• Research Institution: National Cancer Center Japan
• Principal Investigator: Yamashita Satoshi 国立研究開発法人国立がん研究センター, 研究所, ユニット長 (80321876)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 点突然変異

Outline of Final Research Achievements

Somatic mutations with very low frequency, consisting of mostly passenger, are present even in normal tissues without expansion of clonal patches, and form a cancerization field. Recently, methods to measure such ultra-rare mutations have been developed. We established a simple method using sequencing libraries prepared from 100 copies of genomic DNA as template [Cancer Lett. 403: 152, 2017]. In this study, we analyzed normal oral tissues, and found that their mutation frequencies were similar to those of esophageal tissues. In addition, we combined the method with the molecular barcode technology to achieve more accurate analysis. We prepared sequencing libraries with molecular barcodes using a targeted DNA panel for human genomic DNA. We optimized parameters to score true mutations present only in both strands of DNA. To isolate true mutations more efficiently, further improvement in the preparation of the sequencing libraries is in progress.

Free Research Field

分子生物学

Academic Significance and Societal Importance of the Research Achievements

本研究では申請者が新規に開発した超低頻度の点突然変異頻度解析法（Yamashita et al. Cancer Letters 2017, 特願2015-199342）の改良を進めた。さらに口腔、食道がん因子曝露歴（飲酒・喫煙）のある健常人の口腔粘膜から抽出したゲノムDNAについて点突然変異頻度を解析し、食道粘膜と同等の変異頻度であることを確認した。点突然変異頻度解析法については、両ストランドに同一の変異が存在する真の変異を検出することが可能で、かつ大量のリードを必要としないさらに新しい解析法が必要であると考えられた。