LINE-1 Cargo and Reverse Transcriptase Activity Profiles in Extracellular Vesicles from Lung Cancer Cells and Human Plasma

Emma C. Bowers, Alexandre Motta, Ken Knox, Brian S. McKay, Kenneth S. Ramos

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Long Interspersed Element-1 (LINE-1) is an oncogenic human retrotransposon that ‘copies and pastes’ DNA into new locations via reverse transcription. Given that enzymatically active LINE-1 can be exported in extracellular vesicles (EVs), and that LINE-1 mRNA and its two encoded proteins, ORF1p and ORF2p, are required for retrotransposition, the present study examined LINE-1 EV loading patterns relative to reverse transcriptase (RT) activity in vivo and in vitro. Density gradient ultracentrifugation identified conserved patterns of LINE-1 mRNA and protein distribution in EVs, with RT activity readily detected in EV fractions containing both LINE-1 mRNA and protein. Unlike whole cell and tissue lysates, the ORF1p in EVs was detected as a dimer. EVs from ostensibly healthy plasma donors showed variable but consistent ORF1p profiles, with residual levels of LINE-1 mRNA measured in some but not all samples. EVs from cancer cell lines had elevated mean LINE-1 levels and 5–85 times greater RT activity than EVs from normal cells or healthy plasma. EV RT activity was associated with EV LINE-1 mRNA content and was highest in cell lines that also expressed an elevated expression of ORF1p and ORF2p. Given that LINE-1 activation is a hallmark of many cancer types, our findings suggest that an EV LINE-1 ‘liquid biopsy’ may be developed to monitor LINE-1 activity during the course of malignant progression.

Original languageEnglish (US)
Article number3461
JournalInternational journal of molecular sciences
Issue number7
StatePublished - Mar 22 2022


  • BaP
  • Benzo[a]pyrene
  • Exosomes
  • Extracellular vesicles
  • LINE-1
  • Liquid biopsy
  • Lung cancer
  • ORF1p
  • ORF2p
  • Retrotransposition
  • Retrotransposons
  • Reverse transcriptase
  • Extracellular Vesicles/genetics
  • Retroelements
  • Humans
  • RNA, Messenger/genetics
  • Reverse Transcription
  • Lung Neoplasms/genetics
  • Proteins
  • Long Interspersed Nucleotide Elements
  • Endonucleases
  • RNA-Directed DNA Polymerase/genetics

ASJC Scopus subject areas

  • Molecular Biology
  • Spectroscopy
  • Catalysis
  • Inorganic Chemistry
  • Computer Science Applications
  • Physical and Theoretical Chemistry
  • Organic Chemistry


Dive into the research topics of 'LINE-1 Cargo and Reverse Transcriptase Activity Profiles in Extracellular Vesicles from Lung Cancer Cells and Human Plasma'. Together they form a unique fingerprint.

Cite this