Certain DNA sequences have the capability to form DNA secondary structures that have molecular recognition features quite distinct to duplex DNA. In particular, we are interested in a group of four-stranded structures called G-quadruplexes or DNA tetraplexes. Motifs for the formation of G-quadruplexes appear to be rare in the eukaryotic genome but are found in regions of biological significance (e.g., telomeres and promoter regions). We have identified small molecules that target these sequences and affect the rate of formation and unwinding of G- quadruplexes. In this proposal, I describe experiments that will determine the effect of these small molecules on the role that G- quadruplexes play in switch mechanisms in regulatory regions of oncogenes and in stabilizing t-loops in telomeric regions. Other possible roles of G-quadruplexes in recombination and their in vivo existence will also be evaluated. Biophysical methods, including NMR and PAGE, will be used primarily in this study.
The specific aims of this proposal are to (1) determine the molecular mechanism that results in the down- regulation of c-myc by G-quadruplex and i-motif-interactive compounds; (2) determine the molecular structure of the t-loop invasion complex and use this as a guide to develop new telomere- interactive compounds; (3) determine the effect of G-quadruplex-interactive compounds on other protein-G-quadruplex complexes, including the topoisomerase I-G-quadruplex DNA; (4) use LM-PCR to probe for the occurrence of G-quadruplex structures in vivo.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA094166-04
Application #
6896886
Study Section
Bio-Organic and Natural Products Chemistry Study Section (BNP)
Program Officer
Lees, Robert G
Project Start
2002-07-01
Project End
2007-06-30
Budget Start
2005-07-01
Budget End
2006-06-30
Support Year
4
Fiscal Year
2005
Total Cost
$334,337
Indirect Cost
Name
University of Arizona
Department
Pharmacology
Type
Schools of Pharmacy
DUNS #
806345617
City
Tucson
State
AZ
Country
United States
Zip Code
85721
Lin, Clement; Yang, Danzhou (2017) Human Telomeric G-Quadruplex Structures and G-Quadruplex-Interactive Compounds. Methods Mol Biol 1587:171-196
Sun, Daekyu; Hurley, Laurence H (2010) Biochemical techniques for the characterization of G-quadruplex structures: EMSA, DMS footprinting, and DNA polymerase stop assay. Methods Mol Biol 608:65-79
Brooks, Tracy A; Hurley, Laurence H (2010) Targeting MYC Expression through G-Quadruplexes. Genes Cancer 1:641-649
Gonzalez, Veronica; Hurley, Laurence H (2010) The C-terminus of nucleolin promotes the formation of the c-MYC G-quadruplex and inhibits c-MYC promoter activity. Biochemistry 49:9706-14
Dexheimer, Thomas S; Carey, Steven S; Zuohe, Song et al. (2009) NM23-H2 may play an indirect role in transcriptional activation of c-myc gene expression but does not cleave the nuclease hypersensitive element III(1). Mol Cancer Ther 8:1363-77
González, Verónica; Guo, Kexiao; Hurley, Laurence et al. (2009) Identification and characterization of nucleolin as a c-myc G-quadruplex-binding protein. J Biol Chem 284:23622-35
Palumbo, SunMi L; Ebbinghaus, Scot W; Hurley, Laurence H (2009) Formation of a unique end-to-end stacked pair of G-quadruplexes in the hTERT core promoter with implications for inhibition of telomerase by G-quadruplex-interactive ligands. J Am Chem Soc 131:10878-91
Sun, Daekyu; Hurley, Laurence H (2009) The importance of negative superhelicity in inducing the formation of G-quadruplex and i-motif structures in the c-Myc promoter: implications for drug targeting and control of gene expression. J Med Chem 52:2863-74
Dai, Jixun; Ambrus, Attila; Hurley, Laurence H et al. (2009) A direct and nondestructive approach to determine the folding structure of the I-motif DNA secondary structure by NMR. J Am Chem Soc 131:6102-4
Palumbo, SunMi L; Memmott, Regan M; Uribe, Diana J et al. (2008) A novel G-quadruplex-forming GGA repeat region in the c-myb promoter is a critical regulator of promoter activity. Nucleic Acids Res 36:1755-69

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