期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2015
卷号：112
期号：49
页码：15148-15153
DOI：10.1073/pnas.1518008112
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceUnique among the large number of noncoding RNA species, the pericentromeric human satellite II (HSATII) repeat is massively expressed in a broad set of epithelial cancers but is nearly undetectable in normal tissues. Here, we show that deregulation of HSATII expression is tightly linked to growth under nonadherent conditions, and we uncover an unexpected mechanism by which HSATII RNA-derived DNA (rdDNA) leads to progressive elongation of pericentromeric regions in tumors. The remarkable specificity of HSATII overexpression in cancers, together with the consequences of targeting its RT, points to a potential novel vulnerability of cancer cells. Aberrant transcription of the pericentromeric human satellite II (HSATII) repeat is present in a wide variety of epithelial cancers. In deriving experimental systems to study its deregulation, we observed that HSATII expression is induced in colon cancer cells cultured as xenografts or under nonadherent conditions in vitro, but it is rapidly lost in standard 2D cultures. Unexpectedly, physiological induction of endogenous HSATII RNA, as well as introduction of synthetic HSATII transcripts, generated cDNA intermediates in the form of DNA/RNA hybrids. Single molecule sequencing of tumor xenografts showed that HSATII RNA-derived DNA (rdDNA) molecules are stably incorporated within pericentromeric loci. Suppression of RT activity using small molecule inhibitors reduced HSATII copy gain. Analysis of whole-genome sequencing data revealed that HSATII copy number gain is a common feature in primary human colon tumors and is associated with a lower overall survival. Together, our observations suggest that cancer-associated derepression of specific repetitive sequences can promote their RNA-driven genomic expansion, with potential implications on pericentromeric architecture.
关键词：satellites ; reverse transcription ; repeats ; cancer
