Bioreductive aziridinylbenzoquinones, one of the most potent classes of chemotherapeutic drugs, are alkylating agents that bind covalently to DNA. It is recognized that the basis for the activity of many anti-cancer agents is related to their ability to modify the structure of DNA, thus inhibiting DNA or RNA synthesis during DNA repair, replication, or transcription processes. The biochemical mechanisms of aziridinylbenzoquinones continue to be unraveled even as the search for more potent, more selective analogues with fewer toxic side effects moves forward. The clinical value of aziridinylbenzoquinones has promoted ongoing interest in developing new analogues, and this continuing interest has spurred the need for sensitive, versatile analytical methods that can be used to determine the structures of the resulting DNA adducts and DNA crosslinks, to evaluate the DNA sequence/site selectivities and reactivities of these alkylating agents, and to better understand the ways that the resulting DNA adducts interact with relevant proteins in a way that leads to anticancer activities. This proposal will describe the development and application of several innovative mass spectrometric strategies for the structural characterization of DNA adducts and chemical probe strategies for targeting DNA adducts and protein/DNA interactions. The overall goal is to develop new photodissociation techniques in conjunction with electrospray ionization mass spectrometry, as well as chemical probe methods based on selective reactivities and derivatization strategies, to create a tool-kit of mass spectrometric methods for characterizing new DNA alkylating agents. Our innovative technological approaches and the resulting outcomes will provide insights into site/sequence selectivity of alkylating agents, offer rapid and sensitive structural characterization of DNA adducts, and offer a new approach for mapping DNA/protein interactions. An array of bioreductive aziridinylbenzoquinones will be synthesized, including ones in which the alkyl substituents are modified to alter the reduction potentials and modulate their cytotoxicities, with the aim of increasing the selectivity of the quinones and constructing structure/reactivity relationships based on the ESI-MS (electrospray ionization mass spectrometry) methods and companion cytoxicity assays.
The activities of many anticancer agents are dependent on their ability to bind DNA, either via formation of interstrand cross-links or formation of monoadducts which involve binding to a single DNA site. This research enables the design of new anticancer aziridinylbenzoquinones and advances the analysis of DNA-drug adducts by innovative mass spectrometric strategies.
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