A number of clinically important antitumor agents such as cisplatin, cyclophosphamide (a nitrogen mustard) or carmustine (BCNU, a chloro ethyl nitroso urea) form DNA interstrand crosslinks (ICLs) as key cytotoxic lesions. ICLs covalently link two strands of a DNA duplex and therefore provide a potent block to DNA replication and transcription. Despite the enormous success of ICL-forming agents in treating a large variety of tumors, the occurrence of resistance caused by the repair of ICLs (and other mechanisms) and the occurrence of secondary tumors remain significant problems. Studies aimed at understanding the biological responses triggered by ICLs formed by antitumor agents have been hampered by the limited availability of site-specific ICLs for biochemical and cell biological studies. We have developed new methodology for the synthesis of site-specific ICLs formed by nitrogen mustards and chloro ethyl nitroso ureas to overcome this limitation. This will enable us to synthesize structurally diverse ICLs and incorporate them into longer oligonucleotides and plasmids for the study of ICL repair. In collaboration with the laboratory of Johannes Walter (Harvard Medical School) these substrates were used to establish the first defined biochemical system for the study of replication- dependent ICL repair, revealing incisions around the ICL and translesion synthesis past an unhooked ICL as key steps. Along with preliminary studies exploring the reactions of translesion synthesis polymerases with ICL templates, these studies provide the foundation for the proposed studies of structure-function relationships in ICL repair. The guiding hypothesis of these studies is that differences in ICL structure will affect the translesion synthesis and nucleotide excision repair steps in ICL repair in particular, and that these differences have important implication for therapeutic outcomes in antitumor chemotherapy.
In Aim 1 we propose to further our efforts to synthesize ICLs that link the DNA through the major groove or base-pairing surfaces, generating ICLs that induce severe, intermediate, mild or no distortion in the DNA double helix. We will furthermore synthesize ICLs in structures that represent intermediates in ICL repair to study how they are processed by DNA polymerases.
In Aim 2, we will characterize the structures of these ICLs by NMR spectroscopy and molecular dynamics simulations to gain detailed insights into how the various ICLs affect DNA structure.
In Aim 3, we will investigate how these structurally diverse ICLs are processed in replication-dependent ICL repair and how the structures of the ICLs influence how they are processed by translesion synthesis polymerases. We expect that these studies will reveal commonalities and also important differences of how structurally diverse ICLs are processed in human cells. Our studies should provide important insights into the mechanisms that underlie resistance of tumors to crosslinking agents used in cancer chemotherapy as well as the formation of secondary tumors. Since our studies involve ICLs formed by antitumor agents as well as ones with novel structures, they could lead to the development of antitumor agents with improved properties.

Public Health Relevance

Cisplatin, nitrogen mustards and chloro ethyl nitroso ureasare among the most successful drugs used in antitumor therapy. They exert their effect by forming DNA adducts called interstrand crosslinks as the most important therapeutic lesions. Despite the clinical success of these drugs, the occurrence of resistance in tumor cells and formation of secondary tumors are significant problems. Our studies aimed at understanding how structurally diverse DNA adducts formed by antitumor agents are processed in human cells will have significant impact on the understanding and overcoming of resistance of tumor cells to known drugs and might lead to the development of new antitumor agents with improved properties.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA165911-04
Application #
8840901
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Knowlton, John R
Project Start
2012-07-01
Project End
2016-04-30
Budget Start
2015-05-01
Budget End
2016-04-30
Support Year
4
Fiscal Year
2015
Total Cost
Indirect Cost
Name
State University New York Stony Brook
Department
Pharmacology
Type
Schools of Medicine
DUNS #
804878247
City
Stony Brook
State
NY
Country
United States
Zip Code
11794
Jin, Hyeonseok; Roy, Upasana; Lee, Gwangrog et al. (2018) Structural mechanism of DNA interstrand cross-link unhooking by the bacterial FAN1 nuclease. J Biol Chem 293:6482-6496
Beagan, Kelly; Armstrong, Robin L; Witsell, Alice et al. (2017) Drosophila DNA polymerase theta utilizes both helicase-like and polymerase domains during microhomology-mediated end joining and interstrand crosslink repair. PLoS Genet 13:e1006813
Pande, Paritosh; Ji, Shaofei; Mukherjee, Shivam et al. (2017) Mutagenicity of a Model DNA-Peptide Cross-Link in Human Cells: Roles of Translesion Synthesis DNA Polymerases. Chem Res Toxicol 30:669-677
Castaño, Alejandra; Roy, Upasana; Schärer, Orlando D (2017) Preparation of Stable Nitrogen Mustard DNA Interstrand Cross-Link Analogs for Biochemical and Cell Biological Studies. Methods Enzymol 591:415-431
Roy, Upasana; Schärer, Orlando D (2016) Involvement of translesion synthesis DNA polymerases in DNA interstrand crosslink repair. DNA Repair (Amst) 44:33-41
Wickramaratne, Susith; Ji, Shaofei; Mukherjee, Shivam et al. (2016) Bypass of DNA-Protein Cross-links Conjugated to the 7-Deazaguanine Position of DNA by Translesion Synthesis Polymerases. J Biol Chem 291:23589-23603
Roy, Upasana; Mukherjee, Shivam; Sharma, Anjali et al. (2016) The structure and duplex context of DNA interstrand crosslinks affects the activity of DNA polymerase ?. Nucleic Acids Res 44:7281-91
Pizzolato, Julia; Mukherjee, Shivam; Schärer, Orlando D et al. (2015) FANCD2-associated nuclease 1, but not exonuclease 1 or flap endonuclease 1, is able to unhook DNA interstrand cross-links in vitro. J Biol Chem 290:22602-11
Mukherjee, Shivam; Guainazzi, Angelo; Schärer, Orlando D (2014) Synthesis of structurally diverse major groove DNA interstrand crosslinks using three different aldehyde precursors. Nucleic Acids Res 42:7429-35
Hodskinson, Michael R G; Silhan, Jan; Crossan, Gerry P et al. (2014) Mouse SLX4 is a tumor suppressor that stimulates the activity of the nuclease XPF-ERCC1 in DNA crosslink repair. Mol Cell 54:472-84

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