Although we used to believe that all retrotransposition occurred in the germ line in humans, over the past 10 years it has become clear that somatic retrotransposition, especially of LINE1s (L1s), is prominent, at least in the brain and in epithelial cancers. A number of groups have shown retrotransposition in neural precursor cells and the adult brain. Likewise, a number of groups including our own have shown significant retrotransposition in gastrointestinal cancers. A key finding of our studies is that most L1 insertions in GI cancers occur very early in cancer development. Indeed, some of the insertions are found in low concentration (detected only by nested PCR) in normal cells, but they become essentially clonal in the cancer (detected by conventional PCR). ln this application, we strive to answer two big questions in the field. First, does significant retrotransposition occur in adult somatic tissues outside of the brain and, if so, at what frequency? In this aim we will study L1 insertions in single normal cells near the tumors to find what fraction of the insertions in the tumor are already present in normal cells. We will determine if retrotransposition rate is greater in normal cells or in tumor cells. We will also stuy the frequency of insertions in single normal cells not associated with cancer and from various organs to determine if some tissue types have a greater propensity for retrotransposition than others. The second big question is: Does L1 somatic retrotransposition have any significant role in the etiology of cancer? We need to determine whether we can alter the cellular phenotype towards normal by deletion of somatic L1 insertions found in cancer-related genes in cancer-derived cell lines.

Public Health Relevance

Retrotransposons are pieces of DNA in the human genome that can be mobilized to a new genomic site by a duplicative copy and paste process. We are exploring the role of these DNA elements in cancer, and have found that somatic 'jumping' in gastrointestinal cancers is quite common. The major Aims of this application are to discover 1) whether L1 'jumping' predominantly occurs in normal cells that develop into cancer, and 2) whether these insertions play a role in tumor development.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM099875-05
Application #
9105045
Study Section
Genetics of Health and Disease Study Section (GHD)
Program Officer
Janes, Daniel E
Project Start
2012-05-01
Project End
2020-03-31
Budget Start
2016-07-11
Budget End
2017-03-31
Support Year
5
Fiscal Year
2016
Total Cost
Indirect Cost
Name
Johns Hopkins University
Department
Genetics
Type
Schools of Medicine
DUNS #
001910777
City
Baltimore
State
MD
Country
United States
Zip Code
21205
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Kazazian Jr, Haig H; Moran, John V (2017) Mobile DNA in Health and Disease. N Engl J Med 377:361-370
Richardson, Sandra R; Gerdes, Patricia; Gerhardt, Daniel J et al. (2017) Heritable L1 retrotransposition in the mouse primordial germline and early embryo. Genome Res 27:1395-1405
Kazazian Jr, Haig H (2017) Fifty years in human genetics--a career retrospective. FASEB J 31:3712-3718
Doucet, Tara T; Kazazian Jr, Haig H (2016) Long Interspersed Element Sequencing (L1-Seq): A Method to Identify Somatic LINE-1 Insertions in the Human Genome. Methods Mol Biol 1400:79-93
Doucet-O'Hare, Tara T; Sharma, Reema; Rodi?, Nemanja et al. (2016) Somatically Acquired LINE-1 Insertions in Normal Esophagus Undergo Clonal Expansion in Esophageal Squamous Cell Carcinoma. Hum Mutat 37:942-54
Mandal, Prabhat K; Kazazian Jr, Haig H (2016) Purification of L1-Ribonucleoprotein Particles (L1-RNPs) from Cultured Human Cells. Methods Mol Biol 1400:299-310
Goodier, John L; Pereira, Gavin C; Cheung, Ling E et al. (2015) The Broad-Spectrum Antiviral Protein ZAP Restricts Human Retrotransposition. PLoS Genet 11:e1005252
Ewing, Adam D; Gacita, Anthony; Wood, Laura D et al. (2015) Widespread somatic L1 retrotransposition occurs early during gastrointestinal cancer evolution. Genome Res 25:1536-45
Doucet-O'Hare, Tara T; Rodi?, Nemanja; Sharma, Reema et al. (2015) LINE-1 expression and retrotransposition in Barrett's esophagus and esophageal carcinoma. Proc Natl Acad Sci U S A 112:E4894-900

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