Hurley, L., Rezler, E. M., Bearss, D. J., & Hurley, L. -. (2003). Telomere inhibition and telomere disruption as processes for drug targeting. Annual review of pharmacology and toxicology, 43.
The components and cofactors of the holoenzyme telomerase and its substrate telomeric DNA are attractive targets for anticancer agents that act by inhibiting the activity of telomerase. This review outlines recent advances in telomerase inhibition that have been achieved using antisense oligonucleotides and ribozymes that target the telomerase mRNA or its hTR RNA template. Although these are potent catalytic inhibitors of telomerase, they are challenging to implement in the clinic due to their delayed effectiveness. Drugs that directly bind to the telomeres, the complex structures that are associated at the telomeric ends, and stabilize secondary DNA structures such as G-quadruplexes are also potent inhibitors of telomerase. Special focus is given here to the telomeres, the biological machinery that works in tandem with telomerase to elongate telomeres, the causes of telomere disruption or dysfunction, and the consequences of disruption/dysfunction on the activity and design of anticancer agents.
Warner, S. L., Bashyam, S., Vankayalapati, H., Bearss, D. J., Han, H., D., D., & Hurley, L. H. (2006). Identification of a lead small-molecule inhibitor of the Aurora kinases using a structure-assisted, fragment-based approach. Molecular Cancer Therapeutics, 5(7), 1764-1773.
PMID: 16891462;Abstract:
Aurora A and Aurora B are potential targets for anticancer drug development due to their roles in tumorigenesis and disease progression. To identify small-molecule inhibitors of the Aurora kinases, we undertook a structure-based design approach that used three-dimensional structural models of the Aurora A kinase and molecular docking simulations of chemical entities. Based on these computational methods, a new generation of inhibitors derived from quinazoline and pyrimidine-based tricyclic scaffolds were synthesized and evaluated for Aurora A kinase inhibitory activity, which led to the identification of 4-(6,7-dimethoxy-9H-1, 3,9-triaza-fluoren-4-yl)-piperazine-1-carbothioic acid [4-(pyrimidin-2-ylsulfamoyl)-phenyl]-amide. The lead compound showed selectivity for the Aurora kinases when it was evaluated against a panel of diverse kinases. Additionally, the compound was evaluated in cell-based assays, showing a dose-dependent decrease in phospho-histone H3 levels and an arrest of the cell cycle in the G2-M fraction. Although biological effects were observed only at relatively high concentrations, this chemical series provides an excellent starting point for drug optimization and further development. Copyright © 2006 American Association for Cancer Research.
Kendrick, S., Akiyama, Y., Hecht, S. M., & Hurley, L. H. (2009). The i-motif in the bcl-2 P1 promoter forms an unexpectedly stable structure with a unique 8:5:7 loop folding pattern. Journal of the American Chemical Society, 131(48), 17667-17676.
PMID: 19908860;PMCID: PMC2787777;Abstract:
Transcriptional regulation of the bcl-2 proto-oncogene is highly complex, with the majority of transcription driven by the P1 promoter site and the interaction of multiple regulatory proteins. A guanine- and cytosine-rich (GC-rich) region directly upstream of the P1 site has been shown to be integral to bcl-2 promoter activity, as deletion or mutation of this region significantly increases transcription. This GC-rich element consists of six contiguous runs of guanines and cytosines that have the potential to adopt DNA secondary structures, the G-quadruplex and i-motif, respectively. Our laboratory has previously demonstrated that the polypurine-rich strand of the bcl-2 promoter can form a mixture of three different G-quadruplex structures. In this current study, we demonstrate that the complementary polypyrimidine-rich strand is capable of forming one major intramolecular i-motif DNA secondary structure with a transition pH of 6.6. Characterization of the i-motif folding pattern using mutational studies coupled with circular dichroic spectra and thermal stability analyses revealed an 8:5:7 loop conformation as the predominant structure at pH 6.1. The folding pattern was further supported by chemical footprinting with bromine. In addition, a novel assay involving the sequential incorporation of a fluorescent thymine analog at each thymine position provided evidence of a capping structure within the top loop region of the i-motif. The potential of the GC-rich element within the bcl-2 promoter region to form DNA secondary structures suggests that the transition from the B-DNA to non-B-DNA conformation may play an important role in bcl-2 transcriptional regulation. Furthermore, the two adjacent large lateral loops in the i-motif structure provide an unexpected opportunity for protein and small molecule recognition. © 2009 American Chemical Society.
Hurley, L., Seenisamy, J., Rezler, E. M., Powell, T. J., Tye, D., Gokhale, V., Joshi, C. S., Siddiqui-Jain, A., & Hurley, L. -. (2004). The dynamic character of the G-quadruplex element in the c-MYC promoter and modification by TMPyP4. Journal of the American Chemical Society, 126(28).
The nuclease hypersensitivity element III1 (NHE III1) upstream of the P1 and P2 promoters of c-MYC controls 80-90% of the transcriptional activity of this gene. The purine-rich strand in this region can form a G-quadruplex structure that is a critical part of the silencer element for this promoter. We have demonstrated that this G-quadruplex structure can form a mixture of four biologically relevant parallel-loop isomers, which upon interaction with the cationic porphyrin TMPyP4 are converted to mixed parallel/antiparallel G-quadruplex structures.
Grand, C. L., Powell, T. J., Nagle, R. B., Bearss, D. J., Tye, D., Gleason-Guzman, M., & Hurley, L. H. (2005). Erratum (Retracted Article): Mutations in the G-quadruplex silencer element and their relationship to c-MYC overexpression, NM23 repression, and therapeutic rescue (Proceedings of the National Academy of Sciences of the United States of America (April 20, 2004) 101:16 (6140-6145)). Proceedings of the National Academy of Sciences of the United States of America, 102(2), 516-.
