DNA replication in eukaryotic cells is tightly controlled so that the genome is replicated once and only once per cell cycle. Disruption of DNA replication control due to impaired replication licensing mechanisms causes DNA rereplication, which often leads to genome instability, contributing to tumorigenesis. In support of this, deregulated overexpression of the licensing factor Cdt1 is associated with a large panel of tumors. Furthermore, a number of oncogenes are found to induce DNA rereplication at the early stage of cancer development. Thus, DNA rereplication is a driving force for tumorigenesis. DNA double-strand breaks (DSBs) are frequently formed during rereplication, but the mechanisms underlying the repair of rereplication-induced DSBs to maintain genome integrity are still elusive. Since DNA rereplication produces extra copies of DNA segments and generates multiple DSBs, the associated repair process is expected to be much more complex than that for a general single DSB. In this study, we will investigate the detailed mechanisms of how rereplicated DNA is removed, and how DSBs generated at rereplication forks are repaired by using our newly established novel EGFP-based DSB repair substrates. We will also study the consequences for genome instability that rereplication would cause, such as chromosomal lesions and gene amplification. Since DNA rereplication is an integral aspect of tumorigenesis, our proposed study will provide insights into new mechanisms associated with tumor initiation and development, and will also shed light on developing strategies for cancer diagnosis and treatment in the future.

Public Health Relevance

DNA rereplication or over-replication of chromosomal DNA often contributes to genome instability, which is highly associated with cancer development. Therefore, it is of great importance to understand how DNA lesions generated by rereplication are repaired to preserve genome integrity. Since DNA rereplication is a driving force for tumorigenesis, the proposed studies will shed light on the causes of cancer development and will ultimately help develop new therapeutic interventions for human diseases associated with genome instability and cancer.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM080677-06
Application #
9059101
Study Section
Radiation Therapeutics and Biology Study Section (RTB)
Program Officer
Reddy, Michael K
Project Start
2010-09-15
Project End
2019-04-30
Budget Start
2016-05-01
Budget End
2017-04-30
Support Year
6
Fiscal Year
2016
Total Cost
Indirect Cost
Name
Scripps Research Institute
Department
Type
DUNS #
781613492
City
La Jolla
State
CA
Country
United States
Zip Code
92037
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