3-Amino-1,2,4-benzotriazine 1,4-dioxide (tirapazamine, TPZ) is a bioreductively-activated DNA-damaging agent that selectively kills the hypoxic cells found in virtually all solid tumors. This compound shows great clinical promise and is currently being examined in more than ten different clinical trials, including several phase III studies. Importantly, TPZ damages DNA via a completely novel sequence of chemical reactions in which the one-electron reduced drug initiates radical-mediated DNA damage and then the drug or its metabolites transfer oxygen atoms from their N-oxide functional groups to the resulting DNA radicals, thus, converting them to strand cleavage sites. While the medicinal properties of TPZ have been extensively investigated, many of its biologically relevant chemical properties remain poorly understood. The growing clinical interest in TPZ provides a practical incentive to characterize the relevant chemistry of this drug. In addition, characterization of this new chemical motif that efficiently delivers cytotoxic DNA-damaging radicals to the interior of hypoxic cells may be of fundamental interest in both medicinal chemistry and toxicology. The work described in this proposal is divided into three Specific Aims: 1. How does TPZ generate radical lesions on DNA? Does the drug serve to deliver the known DNA-damaging agent hydroxyl radical to hypoxic cells? How do the conditions of low oxygen and low pH found in tumor cells combine to facilitate DNA damage by the drug? 2. What is the chemical mechanism by which TPZ and its metabolites transfer oxygen atoms from their N-oxide functional groups to DNA radicals? This unprecedented reaction allows the drug to efficiently damage DNA under hypoxic conditions and may play a central role in defining the structural nature of the final DNA lesions caused by TPZ. 3. We propose studies to characterize the structural nature of the DNA strand breaks and base damage mediated by TPZ. These studies will explore the possibility that the unusual conditions under which TPZ operates, along with the unique chemical properties of the drug, lead to a unique spectrum of DNA lesions that confront cells with social challenges to their DNA-repair systems. ? ?

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
1R01CA100757-01
Application #
6602990
Study Section
Special Emphasis Panel (ZRG1-PTHB (03))
Program Officer
Forry, Suzanne L
Project Start
2003-03-14
Project End
2007-02-28
Budget Start
2003-03-14
Budget End
2004-02-29
Support Year
1
Fiscal Year
2003
Total Cost
$170,382
Indirect Cost
Name
University of Missouri-Columbia
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
153890272
City
Columbia
State
MO
Country
United States
Zip Code
65211
Sarkar, Ujjal; Hillebrand, Roman; Johnson, Kevin M et al. (2017) Application of Suzuki-Miyaura and Buchwald-Hartwig Cross-coupling Reactions to the Preparation of Substituted 1,2,4-Benzotriazine 1-Oxides Related to the Antitumor Agent Tirapazamine. J Heterocycl Chem 54:155-160
Rajapakse, Anuruddha; Hillebrand, Roman; Lewis, Sarah M et al. (2014) Crystal structure of N-(quinolin-6-yl)hydroxyl-amine. Acta Crystallogr Sect E Struct Rep Online 70:322-4
Shen, Xiulong; Rajapakse, Anuruddha; Gallazzi, Fabio et al. (2014) Isotopic labeling experiments that elucidate the mechanism of DNA strand cleavage by the hypoxia-selective antitumor agent 1,2,4-benzotriazine 1,4-di-N-oxide. Chem Res Toxicol 27:111-8
Parsons, Zachary D; Gates, Kent S (2013) Thiol-dependent recovery of catalytic activity from oxidized protein tyrosine phosphatases. Biochemistry 52:6412-23
Rajapakse, Anuruddha; Linder, Collette; Morrison, Ryan D et al. (2013) Enzymatic conversion of 6-nitroquinoline to the fluorophore 6-aminoquinoline selectively under hypoxic conditions. Chem Res Toxicol 26:555-63
Rajapakse, Anuruddha; Barnes, Charles L; Gates, Kent S (2011) Synthesis and Crystal Structure of the Azoxydichinyl Helicene, Pyrido[3,2-f]quinolino[6,5-c]cinnoline 5-Oxide Monohydrate. J Chem Crystallogr 41:1712-1716
Sarkar, Ujjal; Glaser, Rainer; Parsons, Zack D et al. (2010) Synthesis, Crystal Structure, and Rotational Energy Profile of 3-Cyclopropyl-1,2,4-benzotriazine 1,4-Di-N-oxide. J Chem Crystallogr 40:624-629
Junnotula, Venkatraman; Rajapakse, Anuruddha; Arbillaga, Leire et al. (2010) DNA strand cleaving properties and hypoxia-selective cytotoxicity of 7-chloro-2-thienylcarbonyl-3-trifluoromethylquinoxaline 1,4-dioxide. Bioorg Med Chem 18:3125-32
Gates, Kent S (2009) An overview of chemical processes that damage cellular DNA: spontaneous hydrolysis, alkylation, and reactions with radicals. Chem Res Toxicol 22:1747-60
Junnotula, Venkatraman; Sarkar, Ujjal; Sinha, Sarmistha et al. (2009) Initiation of DNA strand cleavage by 1,2,4-benzotriazine 1,4-dioxide antitumor agents: mechanistic insight from studies of 3-methyl-1,2,4-benzotriazine 1,4-dioxide. J Am Chem Soc 131:1015-24

Showing the most recent 10 out of 16 publications