Laurence Hurley

Abstract:

An efficient convergent synthesis of a homologous series of C8-linked pyrrolobenzodiazepine dimers with remarkable DNA interstrand cross-linking activity and potent in vitro cytotoxicity is reported. The 'amino thioacetal' cyclization procedure was used to produce the electrophilic DNA-interactive N10-C11 imine moiety during the final synthetic step. In order to construct the key A-ring fragments (9a-d), a versatile convergent approach has been developed to join two units of vanillic acid with α,ω-dihaloalkanes of varying length to provide the required bis(4-carboxy-2-methoxyphenoxy)alkanes while avoiding the formation of mixtures of monoalkylated and bisalkylated products.

PMID: 8387334;Abstract:

(+)-CC-1065 is a biologically potent DNA-reactive antitumor antibiotic produced by Streptomyces zelensis. In a previous study we have reported that (+)-CC-1065 produces bending of DNA that has similarities to that intrinsically associated with A-tracts [Lin, C. H., Sun, D., & Hurley, L. H. (1991) Chem. Res. Toxicol. 4, 21-26]. In this article we provide evidence using a combination of non-denaturing gel analysis, hydroxyl-radical footprinting, and high-field NMR for both distinctions between the two types of bends and the importance of junctions in both types of bends. For A-tracts we demonstrate that the locus of bending is at the center of an A-tract and that upon modification of the 3′ adenine with (+)-CC-1065 this locus is moved less than 1 base pair to the 3′ side, and the bending magnitude is significantly increased. For drug bonding sequences such as 5′-AGTTA* or 5′-GATTA* (where * denotes the drug bonding site), the locus of bending is found to be between the two thymines, and the bending is focused over a 2-base-pair sequence rather than a 5-base-pair sequence, as is the case for the A-tract. An important distinction between an A-tract intrinsic bend and a (+)-CC-1065-induced bend is the effect of temperature. While, as shown previously, the magnitude of A-tract bending increases with decrease in temperature, for drug-induced bending of 5′-AGTTA* the bending magnitude increases with increased temperature. Hydroxyl-radical footprinting of the drug-modified 5′-AGTTA* sequence shows a decrease in cleavage centered around the TT sequence, which is presumably associated with a decrease in minor groove width. In a parallel study, the non-self-complementary 12-mer duplex (5′-GGCGGAGTTA*GG-3′)·(5′-CCTAACTC-CGCC-3′) (Figure 2B) and the corresponding (+)-CC-1065-modified duplex adduct were examined thoroughly by one- and two-dimensional ¹H NMR and NOESY restrained molecular mechanics and dynamics calculations. Both the 12-mer duplex and the (+)-CC-1065-12-mer duplex adduct maintain an overall B-form DNA with the anti base orientation throughout in aqueous solution at room temperature. The 18C nucleotide of both the 12-mer duplex and its drug-modified adduct has an average C3′-endo sugar pucker The 12-mer duplex exhibits a unique internal motion at the 16A nucleotide, which is located to the 3′ side of the complementary partner of the covalently modified adenine, and a major kink at the 18C-19T step Following covalent bonding with (+)-CC-1065, the discontinuity around 18C is entrapped and further exaggerated. In addition, the 12-mer duplex adduct displays a compression of the minor groove at the 8T to 9T step and widening on both sides, but especially abruptly at the covalent modification site. Structurally the 12-mer duplex adduct bears many similarities to a bent DNA structure, which is intrinsically associated with A-tracts. The major drug-induced distortion on DNA is localized at the 9T and 10A step of the covalently modified strand. A truncated junction model for the drug-entrapped/induced bending of DNA is proposed, and a comparison to intrinsic A-tract bending is made. © 1993 American Chemical Society.

PMID: 17041088;Abstract:

To address the increased need to understand the similarities and differences in targeting Aurora A or Aurora B for the treatment of cancer, we systematically evaluated the relative importance of Aurora A and/or Aurora B as molecular targets using antisense oligonucleotides. It was found that perturbations in Aurora A and Aurora B signaling result in growth arrest and a apoptosis preferentially in cancer cells. The biological fingerprints of Aurora A and Aurora B inhibition were compared and contrasted in efforts to identify the superior therapeutic target. Due to the different biological responses, we conclude that each Aurora kinase should be treated as autonomous drug targets, which can be targeted independently or in combination. We observed no advantages to targeting both kinases simultaneously and feel that an Aurora A-targeted therapy may have some beneficial consequences over an Aurora B -targeted therapy, such as mitotic arrest and the rapid induction of apoptosis. Copyright © 2006 American Association for Cancer Research.

PMID: 19509249;PMCID: PMC3693733;Abstract:

We recently demonstrated the antitumor efficacy of orally administered α-tocopheryloxyacetic acid (α-TEA), a redox silent and nonhydrolyzable derivative of naturally occurring vitamin E. In order to move α-TEA closer to the clinic to benefit patients with breast cancer, the present study had two goals. First, to determine the minimal effective treatment dose; and second, to test the efficacy of dietary administration of α-TEA in the clinically relevant MMTV-PyMT mouse model of spontaneous breast cancer that more closely resembles human disease. The minimal effective dose of α-TEA was evaluated in the transplantable 4T1 tumor model and we show a dose-dependent decrease of primary tumor growth and reduction of metastatic spread to the lung. Six-week-old MMTV-PyMT mice were treated with oral α-TEA for 9 weeks, with no apparent signs of drug toxicity. The α-TEA treatment delayed tumor development and significantly slowed tumor progression, resulting in a 6-fold reduction of the average cumulative tumor size. In addition, oral α-TEA caused an 80% reduction in spontaneous metastases. In situ analysis of tumor tissue identified apoptosis as an important mechanism of α-TEA-mediated tumor suppression in addition to inhibition of tumor cell proliferation. This study shows, for the first time, the ability of orally administered α-TEA to delay tumor onset and to inhibit the progression and metastatic spread of a clinically relevant model of spontaneous breast cancer. Our finding of the high efficacy in this tumor model highlights the translational potential of oral α-TEA therapy. Copyright © 2009 American Association for Cancer Research.

PMID: 10857992;Abstract:

Telomeres and telomerase have been subjects to a tremendous attention from scientists and oncologists during the past 5 years. This interest has been motivated by the potential of telomerase as a tumor marker for the diagnosis and the prognosis of cancer. The possible use of telomerase or telomeres as new targets for anticancer drugs also triggered investigations. The expression of telomerase was found in overall 85% of cancers. Telomerase is early expressed during oncogenesis with a gradient indicating that a high level of telomerase expression could be associated with a bad prognosis. Therefore, drugs targeting telomerase and telomeres might be useful in many human tumors with little restrictions regarding the tumor type or on the stage of the disease. Moreover, since telomerase is not or slightly expressed in normal cells, it has been postulated that drugs targeting telomerase would induce low toxicity. The race for the discovery of telomerase inhibitors has started while the identification of the components controlling telomerase, telomeres, cell survival, senescence, and apoptosis was still in progress. The recent identification of components regulating telomere length and telomerase expression (TRF1, TRF2, and tankyrase) opened a variety of new opportunities to control telomerase/telomere interactions. Meanwhile, a proof of principle was provided that changing telomere interactions with telomere binding proteins by chemical or biological means can induce cancer cell death. Interestingly, recent data challenge the old paradigm which suggested that a long exposure to telomerase and telomere inhibitors is necessary to induce anticancer effects. In this paper, we review the most recent information concerning the regulation of telomere length and telomerase expression, with emphasis on mechanisms that might translate into new drug discovery.