The covalent modification of DNA is believed to be the initial step in chemical carcinogenesis. Exposure to carcinogens is often a result of environmental or work conditions, diet or smoking. In recent years, a number of heterocyclic amines (HCAs) have been isolated from cooked meats;the HCAs are highly mutagenic in bacterial assays and potent haptocarcinogens in rodents and non-human primates. HCA-DNA adducts have been detected from human tissue after exposure to dietary relevant doses. Human exposure to HCAs is widespread and usually occurs over a lifetime;epidemiological studies have linked red meat consumption with increased risk of colorectal, breast, and prostate cancers. As such, many HCAs have been classified as """"""""reasonably anticipated to be human carcinogens"""""""" by the National Toxicology Program and are likely to play a significant role in diet related human cancers. We have proposed an extensive program that interactively uses chemical synthesis, structural biology, polymerase enzymology, and DNA repair studies to define the influence of local DNA sequence and the chemical nature of HCA-adducts on the etiology of HCA carcinogenesis. A foundation of this program is the ability of the PIs lab to synthesize oligonucleotides containing structurally defined C8- and N2-dG adducts of HCAs (Aim 1). Many HCAs are potent inducers of frameshift mutations and we will focus on HCA-adducts in frameshift prone sequences. Frameshift inactivation of tumor suppressor genes is observed in many human colorectal cancers. The conformation of duplex DNA containing HCA adducts will be studied by a variety of techniques including multi-dimensional NMR;the HCA-modified duplexes will be examined opposite dC in a full-length complement strand (Aim 2) as well as opposite a two-base deletion (Aim 3). In addition, we will pursue crystallographic analysis of pre- and post-insertion complexes of HCA-modified duplexes bound to the model Y-family polymerase Dpo4. A key hypothesis of this program is that the precise conformation of the slipped mutagenic intermediate will correlate to the adduct's propensity to induced frameshifts. This will be tested by in vitro replication studies of HCA-modified templates using prokaryotic and human Y-family DNA polymerases (Aim 4). The extension products will be sequenced using an LC-ESI-MS-MS analysis developed at Vanderbilt. Modified DNA templates and primers designed to mimic discrete intermediates in the frameshift mechanism will also be studied. Finally, we propose to correlate the conformation of the HCA adducts with lesion recognition by the repair proteins UvrA and XPC7HR23B (Aim 5).
A family of chemical compounds collectively referred to as heterocyclic amines (HCAs) are produced at part- per-billion levels during the cooking of all meats;the HCAs are potent carcinogens in rodents and non-human primate. Epidemiological studies have linked red-meat consumption with increased risk for colorectal, prostate and breast cancer in human populations and the HCAs may contribute to the finding. This research program uses an interdisciplinary approach to better understand the molecular details of HCA induced cancers.
|Sugitani, Norie; Sivley, Robert M; Perry, Kelly E et al. (2016) XPA: A key scaffold for human nucleotide excision repair. DNA Repair (Amst) 44:123-135|
|Stavros, Kallie M; Hawkins, Edward K; Rizzo, Carmelo J et al. (2015) Base-Displaced Intercalated Conformation of the 2-Amino-3-methylimidazo[4,5-f]quinoline N(2)-dG DNA Adduct Positioned at the Nonreiterated G(1) in the NarI Restriction Site. Chem Res Toxicol 28:1455-68|
|Sugitani, Norie; Chazin, Walter J (2015) Characteristics and concepts of dynamic hub proteins in DNA processing machinery from studies of RPA. Prog Biophys Mol Biol 117:206-11|
|Bose, Arindam; Pande, Paritosh; Jasti, Vijay P et al. (2015) DNA polymerases ? and ? cooperatively perform mutagenic translesion synthesis of the C8-2'-deoxyguanosine adduct of the dietary mutagen IQ in human cells. Nucleic Acids Res 43:8340-51|
|Stavros, Kallie M; Hawkins, Edward K; Rizzo, Carmelo J et al. (2014) Base-displaced intercalation of the 2-amino-3-methylimidazo[4,5-f]quinolone N2-dG adduct in the NarI DNA recognition sequence. Nucleic Acids Res 42:3450-63|
|Shell, Steven M; Hawkins, Edward K; Tsai, Miaw-Sheue et al. (2013) Xeroderma pigmentosum complementation group C protein (XPC) serves as a general sensor of damaged DNA. DNA Repair (Amst) 12:947-53|
|Shell, Steven M; Chazin, Walter J (2012) XPF-ERCC1: on the bubble. Structure 20:566-8|
|Christov, Plamen P; Chowdhury, Goutam; Garmendia, Craig A et al. (2010) The C8-2'-deoxyguanosine adduct of 2-amino-3-methylimidazo[1,2-d]naphthalene, a carbocyclic analogue of the potent mutagen 2-amino-3-methylimidazo[4,5-f]quinoline, is a block to replication in vitro. Chem Res Toxicol 23:1076-88|