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Author Notes:

Corresponding author: sdevine@som.umaryland.edu.

E.C.S. performed L1-seq assays, PCR validations, sequencing of somatic L1 insertions, analysis of the two APC alleles, cloning and sequencing of the Chr 17 and Chr 14 FL-L1Hs elements with Sanger capillary sequencing, and bisulfite methylation experiments.

E.J.G. aligned WGS raw sequencing data to the reference genome, generated BAM files, and performed MELT analysis, RNA-seq analysis, FL-L1Hs analysis, PCR validations, and bisulfite analysis.

A.M. performed non-MEI somatic variant analysis and patient data evaluation.

E.J.G. and N.T.C. performed PacBio FL-L1Hs experiments and analysis.

E.C.S., P.M.V., and S.E.D. designed methylation experiments.

E.C.S., E.J.G., and S.E.D. designed experiments, performed data analysis, prepared display items, and wrote the manuscript.

For acknowledgments, please see the full article.

Subjects:

Research Funding:

This work was funded by the following NIH grants: National Cancer Institute (NCI) grant T32 CA154274 (E.C.S.), National Institute of Diabetes and Digestive and Kidney Diseases grant T32 DK067872 (N.T.C.), NCI grant R01 CA077337 (P.M.V.), NCI grant R01 CA166661 (S.E.D.), and National Human Genome Research Institute grant R01 HG002898 (S.E.D.).

Keywords:

  • Science & Technology
  • Life Sciences & Biomedicine
  • Biochemistry & Molecular Biology
  • Biotechnology & Applied Microbiology
  • Genetics & Heredity
  • HUMAN GENOMES
  • APC GENE
  • CELLS
  • EVOLUTION
  • SEQUENCE
  • TRANSCRIPTION
  • MOSAICISM
  • MUTATIONS

A hot L1 retrotransposon evades somatic repression and initiates human colorectal cancer

Journal Title:

Genome Research

Volume:

Volume 26, Number 6

Publisher:

, Pages 745-755

Type of Work:

Article | Final Publisher PDF

Abstract:

Although human LINE-1 (L1) elements are actively mobilized in many cancers, a role for somatic L1 retrotransposition in tumor initiation has not been conclusively demonstrated. Here, we identify a novel somatic L1 insertion in the APC tumor suppressor gene that provided us with a unique opportunity to determine whether such insertions can actually initiate colorectal cancer (CRC), and if so, how this might occur. Our data support a model whereby a hot L1 source element on Chromosome 17 of the patient's genome evaded somatic repression in normal colon tissues and thereby initiated CRC by mutating the APC gene. This insertion worked together with a point mutation in the second APC allele to initiate tumor-igenesis through the classic two-hit CRC pathway. We also show that L1 source profiles vary considerably depending on the ancestry of an individual, and that population-specific hot L1 elements represent a novel form of cancer risk.

Copyright information:

© 2016 Scott et al.

This is an Open Access work distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/).

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