1.Identification, synthesis, and biological evaluation of metabolites of the experimental cancer treatment drugs indotecan (LMP400) and indimitecan (LMP776) and investigation of isomerically hydroxyla
Cinelli MA1, Reddy PV, Lv PC, Liang JH, Chen L, Agama K, Pommier Y, van Breemen RB, Cushman M. J Med Chem. 2012 Dec 27;55(24):10844-62. doi: 10.1021/jm300519w. Epub 2012 Dec 7.
Hydroxylated analogues of the anticancer topoisomerase I (Top1) inhibitors indotecan (LMP400) and indimitecan (LMP776) have been prepared because (1) a variety of potent Top1 poisons are known that contain strategically placed hydroxyl groups, which provides a clear rationale for incorporating them in the present case, and (2) the hydroxylated compounds could conceivably serve as synthetic standards for the identification of metabolites. Indeed, incubating LMP400 and LMP776 with human liver microsomes resulted in two major metabolites of each drug, which had HPLC retention times and mass fragmentation patterns identical to those of the synthetic standards. The hydroxylated indotecan and indimitecan metabolites and analogues were tested as Top1 poisons and for antiproliferative activity in a variety of human cancer cell cultures and in general were found to be very potent. Differences in activity resulting from the placement of the hydroxyl group are explained by molecular modeling analyses.
2.Neuroprotection and repair of 3'-blocking DNA ends by glaikit (gkt) encoding Drosophila tyrosyl-DNA phosphodiesterase 1 (TDP1).
Guo D1, Dexheimer TS2, Pommier Y3, Nash HA4. Proc Natl Acad Sci U S A. 2014 Nov 4;111(44):15816-20. doi: 10.1073/pnas.1415011111. Epub 2014 Oct 20.
Tyrosyl-DNA phosphodiesterase (TDP1) is a phylogenetically conserved enzyme critical for the removal of blocking lesions at the 3' ends of DNA or RNA. This study analyzes the Drosophila TDP1 gene ortholog glaikit (gkt) and its possible role(s) in the repair of endogenous DNA lesions and neuroprotection. To do so, we studied a homozygous PiggyBac insertion (c03958) that disrupts the 5' UTR of gkt. Protein extracts of c03958 flies were defective in hydrolyzing 3'-DNA-tyrosyl residues, demonstrating that gkt is the Drosophila TDP1. Although the mutant is generally healthy and fertile, females exhibit reduced lifespan and diminished climbing ability. This phenotype was rescued by neuronal expression of TDP1. In addition, when c03958 larvae were exposed to bleomycin, an agent that produces oxidative DNA damage, or topoisomerase I-targeted drugs (camptothecin and a noncamptothecin indenoisoquinoline derivative, LMP-776), survivors displayed rough eye patches, which were rescued by neuronal expression of TDP1.
3.Differential and common DNA repair pathways for topoisomerase I- and II-targeted drugs in a genetic DT40 repair cell screen panel.
Maede Y1, Shimizu H, Fukushima T, Kogame T, Nakamura T, Miki T, Takeda S, Pommier Y, Murai J. Mol Cancer Ther. 2014 Jan;13(1):214-20. doi: 10.1158/1535-7163.MCT-13-0551. Epub 2013 Oct 15.
Clinical topoisomerase I (Top1) and II (Top2) inhibitors trap topoisomerases on DNA, thereby inducing protein-linked DNA breaks. Cancer cells resist the drugs by removing topoisomerase-DNA complexes, and repairing the drug-induced DNA double-strand breaks (DSB) by homologous recombination and nonhomologous end joining (NHEJ). Because numerous enzymes and cofactors are involved in the removal of the topoisomerase-DNA complexes and DSB repair, it has been challenging to comprehensively analyze the relative contribution of multiple genetic pathways in vertebrate cells. Comprehending the relative contribution of individual repair factors would give insights into the lesions induced by the inhibitors and genetic determinants of response. Ultimately, this information would be useful to target specific pathways to augment the therapeutic activity of topoisomerase inhibitors. To this end, we put together 48 isogenic DT40 mutant cells deficient in DNA repair and generated one cell line deficient in autophagy (ATG5).
4.The indenoisoquinoline noncamptothecin topoisomerase I inhibitors: update and perspectives.
Pommier Y1, Cushman M. Mol Cancer Ther. 2009 May;8(5):1008-14. doi: 10.1158/1535-7163.MCT-08-0706. Epub 2009 Apr 21.
Because camptothecins are effective against previously resistant tumors and are the only class of topoisomerase I (Top1) inhibitors approved for cancer treatment, we developed the indenoisoquinolines. Like camptothecins, the indenoisoquinolines selectively trap Top1-DNA cleavage complexes and have been cocrystallized with the Top1-DNA cleavage complexes. Indenoisoquinolines show antitumor activity in animal models. They have several advantages over the camptothecins: (a) They are synthetic and chemically stable. (b) The Top1 cleavage sites trapped by the indenoisoquinolines have different genomic locations, implying differential targeting of cancer cell genomes. (c) The Top1 cleavage complexes trapped by indenoisoquinolines are more stable, indicative of prolonged drug action. (d) They are seldom or not used as substrates for the multidrug resistance efflux pumps (ABCG2 and MDR-1). Among the >400 indenoisoquinolines synthesized and evaluated, three have been retained as leads for clinical development by the National Cancer Institute: NSC 706744, NSC 725776 (Indimitecan), and NSC 724998 (Indotecan).