Decreased Mitochondrial Mutagenesis during Transformation of Human Breast Stem Cells into Tumorigenic Cells
Decreased Mitochondrial Mutagenesis during Transformation of Human Breast Stem Cells into Tumorigenic Cells
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DOI：
10.1158/0008-5472.can-15-3462
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发表时间：
2016-08-01
期刊：
影响因子：
11.2
通讯作者：
Loeb, Lawrence A.
中科院分区：
文献类型：
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作者：
Ahn, Eun Hyun;Lee, Seung Hyuk;Loeb, Lawrence A.
罕见的随机突变可能在干细胞休眠期间积累，但DNA测序的技术限制限制了探索这种可能性。在这项研究中，我们采用了最近建立的一种称为双工测序的深度测序方法，对人类乳腺干细胞模型中的线粒体（mt） DNA突变进行了全基因组分析，该模型概括了乳腺癌发生的顺序阶段。使用这种方法，我们发现mtDNA在正常干细胞、永生细胞/肿瘤前细胞和致瘤细胞之间存在显著差异。当正常干细胞变成致瘤细胞时，假定的癌症干细胞样细胞（CSC）数量和mtDNA拷贝数增加。与正常干细胞相比，转化细胞显示出较低的全mtDNA罕见突变频率。预测的mtDNA罕见突变致病性在致瘤细胞中显著低于正常干细胞。正常干细胞中主要的罕见突变类型是C>T/G>A和T>C/A>G转换，而转化细胞中主要的突变类型只有C>T/G >a。我们共检测到1220个罕见的点突变，其中678个是以前未报道的。除了一个可能的例外（m10342t> C），我们没有发现人类乳腺CSCs中表征mtDNA的特异性突变；相反，干细胞的线粒体基因组显示出罕见突变的总体减少。基于我们的工作，我们认为这种减少（特别是T - >C/A - >G转换），而不是特定线粒体突变的存在，可能构成乳腺癌检测的早期生物标志物。我们的研究结果支持了线粒体基因组在正常干细胞向CSCs转化过程中发生巨大改变的假设，并且mtDNA突变特征可能有助于区分正常干细胞和CSCs。(c) 2016年aacr。
Rare stochastic mutations may accumulate during dormancy of stem-like cells, but technical limitations in DNA sequencing have limited exploring this possibility. In this study, we employed a recently established deep-sequencing method termed Duplex Sequencing to conduct a genome-wide analysis of mitochondrial (mt) DNA mutations in a human breast stem cell model that recapitulates the sequential stages of breast carcinogenesis. Using this method, we found significant differences in mtDNA among normal stem cells, immortal/preneoplastic cells, and tumorigenic cells. Putative cancer stem-like cell (CSC) populations and mtDNA copy numbers increased as normal stem cells become tumorigenic cells. Transformed cells exhibited lower rare mutation frequencies of whole mtDNA than did normal stem cells. The predicted mtDNA rare mutation pathogenicity was significantly lower in tumorigenic cells than normal stem cells. Major rare mutation types in normal stem cells are C>T/G>A and T>C/A>G transitions, while only C>T/G>A are major types in transformed cells. We detected a total of 1,220 rare point mutations, 678 of which were unreported previously. With only one possible exception (m10342T>C), we did not find specific mutations characterizing mtDNA in human breast CSCs; rather, the mitochondrial genome of CSCs displayed an overall decrease in rare mutations. On the basis of our work, we suggest that this decrease (in particular T>C/A>G transitions), rather than the presence of specific mitochondrial mutations, may constitute an early biomarker for breast cancer detection. Our findings support the hypothesis that the mitochondrial genome is altered greatly as a result of the transformation of normal stem cells to CSCs, and that mtDNA mutation signatures may aid in delineating normal stem cells from CSCs. (C) 2016 AACR.