Chromosomal rearrangements are a hallmark of cancer cells and constitute a major pathway by which genes that affect tumor initiation and progression become mutated. Such aberrancies can result from defects in double-stranded break (DSB) repair. There are three major pathways of DNA repair in mammalian cells ? the well-studied homology recombination (HR) and non-homologous end joining (NHEJ) pathways, and the poorly characterized, yet highly error-prone alt-NHEJ (alternative-NHEJ) pathway. Genetic rearrangements consistent with alt-NHEJ have been noted both in spontaneous and therapy-related tumors. In this proposal we will focus on polymerase theta (Pol?), a low-fidelity enzyme that we recently identified as a key factor that mediates DSB repair by alt-NHEJ. Given that HR-defective tumors are ?addicted? to repairing DSBs via the alt-NHEJ pathway, we hypothesize that the mutagenic activity of Pol? help establish a genomic landscape that is conducive for aggressive tumor behavior. Additionally, we predict that deleting Pol? in tumors with mutations in the breast cancer susceptibility (BRCA) genes will sensitize cells to DNA damage- inducing therapeutic agents, including radiation therapy, cisplatin and PARP inhibitors. In the second aim, we will investigate the impact of ATM and PARP1 on Pol? is recruited to break sites and how the polymerase modulates damage sites to promote erroneous repair. In addition, we will pursue a proteomic-based approach to highlight the full spectrum of molecular players involved in alt-NHEJ. Ultimately, a full understanding of the mechanistic basis of alt-NHEJ will provide a better understanding of the source of genomic instability during the course of malignancy and guide more effective treatment strategies for the increasing number of patients with HR mutated tumors.

Public Health Relevance

Alt-NHEJ is a robust, yet poorly characterized DNA double stranded-break repair pathway that appears to alter the genome of cancer cells during disease progression. In this proposal we investigate the mechanism by which polymerase theta (Polq) promotes the activity of alt-NHEJ and test its impact on breast cancer progression, focusing primarily on tumors with mutations in the cancer susceptibility genes ? BRCA1 and BRCA2. Our work will provide major insight into a critical mode of DNA repair and will guide more effective radiation and chemotherapy for an increasing number of HR defective tumors.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA229161-03
Application #
10090458
Study Section
Radiation Therapeutics and Biology Study Section (RTB)
Program Officer
Witkin, Keren L
Project Start
2019-02-01
Project End
2024-01-31
Budget Start
2021-02-01
Budget End
2022-01-31
Support Year
3
Fiscal Year
2021
Total Cost
Indirect Cost
Name
New York University
Department
Radiation-Diagnostic/Oncology
Type
Schools of Medicine
DUNS #
121911077
City
New York
State
NY
Country
United States
Zip Code
10016