LINE-1 expression and retrotransposition in Barrett's esophagus and esophageal carcinoma

By studying premalignant conditions, we can gain a better understanding of the sources of genomic instability and improve cancer prevention and treatment. Because retrotransposition has been observed in many gastrointestinal epithelial cancer types, we focused on L1 mobilization as a source of instability in cancer. Here, we demonstrate that L1 retrotransposition is active in esophageal adenocarcinoma and its precursor, Barrett's esophagus (BE). We detected clonal populations with precursor cells marked by L1 retrotransposition events either in the normal esophagus or BE. These clones expanded in the BE or esophageal adenocarcinoma (EAC), indicating that somatic L1 insertions are not only potential mutagens in the development of EAC, but also useful markers of tumor clones as well.