与复制相关的机制在不匹配修复缺陷癌症中增加了CpG> TpG突变负担
Joseph C Ward1, Ignacio Soriano1, Steve Thorn1
1Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, OX3 7DQ, UK.
Genome medicine
|August 25, 2025
概括
有缺陷不匹配检测 (dMutSα) 的不匹配修复缺陷癌症显示CpG> TpG突变增加. 这些突变来自DNA复制错误,而不仅仅是5-甲基细胞素脱胺.
科学领域:
- 基因组学
- 癌症生物学
- 分子瘤学
背景情况:
- 由于未被修复的DNA复制错误,不匹配修复缺陷 (MMRd) 的癌症呈现出单基替代 (SBS) 突变的增加,特别是C> T和T> C.
- 在缺陷不匹配检测 (dMutSα) 的MMRd癌症中观察到过多的CpG> TpG突变,但在缺陷不匹配校正 (dMutLα) 的癌症中没有.
- 虽然CpG>TpG突变通常与5'-甲基细胞素去胺和SBS1签名有关,但证据表明DNA复制错误和特定的MMR缺陷的作用.
研究的目的:
- 研究不匹配修复缺陷 (MMRd) 癌症中CpG> TpG突变增加的机制.
- 作为dMutSα瘤中CpG>TpG突变过量的主要来源,区分5'-甲基细胞酸脱胺和DNA复制错误.
主要方法:
- 来自1803种结直肠癌和596种子宫内膜癌的全基因组测序数据被分析为突变谱和COSMIC突变特征.
- 将C>T突变映射到基因组特征,包括DNA甲基化,复制时间和复制链,以阐明它们的起源.
- 对dMutLα和dMutSα瘤之间的突变模式进行了比较.
主要成果:
- 与dMutLα瘤相比,dMutSα瘤的CpG> TpG突变负担显著增加.
- 在dMutSα癌症中观察到的CpG> TpG突变谱可以通过将SBS1突变添加到dMutLα谱中来解释.
- 与预期相反,CpG> TpG突变在dMutSα和dMutLα癌症中都偏向于主要的DNA复制链,这表明其来源取决于复制.
结论:
- 过多的CpG> TpG和SBS1突变是dMutSα MMRd瘤的特征,体内C> T突变的普遍增加.
- 在dMutSα和dMutLα瘤中,CpG> TpG突变的主要复制链偏差表明DNA复制错误对它们的形成有重大影响.
- 这些发现挑战了在dMutSα癌症中过多的CpG> TpG突变主要来自复制独立的5'- 甲基细胞因子去胺.
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