LINE-1 Retrotransposon as an Emerging Cancer Biomarker: Methylation, RNA, and Protein Markers
Long interspersed element-1 (LINE-1) retrotransposons are normally silenced but become reactivated in many cancers, making them attractive pan-cancer biomarkers. This Clinical Chemistry review evaluates three LINE-1-derived analytes: genomic methylation status, LINE-1-encoded RNAs, and ORF1 protein expression. Advances in NGS and new reagents are overcoming the technical challenges posed by LINE-1's repetitive nature, opening opportunities for clinical applications in cancer diagnosis and monitoring.
The original study
The Human Long Interspersed Element-1 Retrotransposon: An Emerging Biomarker of Neoplasia.
- Authors
- Ardeljan D, Taylor MS, Ting DT, Burns KH
- Journal
- Clinical chemistry
- Type
- Journal Article, Review, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't
- PMID
- 28188229
Original abstract
BACKGROUND: A large portion of intronic and intergenic space in our genome consists of repeated sequences. One of the most prevalent is the long interspersed element-1 (LINE-1, L1) mobile DNA. LINE-1 is rightly receiving increasing interest as a cancer biomarker. CONTENT: Intact LINE-1 elements are self-propagating. They code for RNA and proteins that function to make more copies of the genomic element. Our current understanding is that this process is repressed in most normal cells, but that LINE-1 expression is a hallmark of many types of malignancy. Here, we will consider features of cancer cells when cellular defense mechanisms repressing LINE-1 go awry. We will review evidence that genomic LINE-1 methylation, LINE-1-encoded RNAs, and LINE-1 ORF1p (open reading frame 1 protein) may be useful in cancer diagnosis. SUMMARY: The repetitive and variable nature of LINE-1 DNA sequences poses unique challenges to studying them, but recent advances in reagents and next generation sequencing present opportunities to characterize LINE-1 expression and activity in cancers and to identify clinical applications.