This dissertation is focused on two objectives. The first objective comprises the improvement of the synthesis of (Z)-5-(2-amino-4-oxo-1H-imidazol-5(4H)-ylidene)-2,3,4,5-tetrahydroazepino[3,4-b]indol-1(10H)-one, also referred to as indoloazepine. The second objective is to evaluate indoloazepine as a cellular inhibitor of checkpoint kinase 2 and its use as an adjuvant drug for cancer therapy. The first chapter identifies checkpoint kinase 2 (Chk2) as a viable adjuvant drug target for cancer therapies. The second chapter discusses the improvement in a previously reported synthesis of indoloazepine. The third chapter describes the biological evaluation and the cellular inhibition of Chk2 by indoloazepine. Finally, the fourth chapter describes the use of indoloazepine as a potential chemosensitizer via the nuclear factor-kappa B (NF-êB) pathway.DNA damage induced by ionizing radiation activates the ataxia telangiectasia mutated pathway, resulting in apoptosis or DNA repair. The serine/threonine checkpoint kinase, Chk2 is an important transducer of this DNA damage signaling pathway and mediates the ultimate fate of the cell. Chk2 is an advantageous target for the development of adjuvant drugs for cancer therapy; because inhibition of Chk2 allows normal cells to enter cell cycle arrest and carry out DNA repair, whereas many tumors bypass cell cycle checkpoints. Chk2 inhibitors may thus have a radioprotective affect on normal cells. Previously, our research group reported the synthesis of hymenialdisine-derived indoloazepine and its ability to inhibit the kinase activity of Chk2 using purified kinase. The previous synthesis of indoloazepine reported by the Tepe research group yielded indoloazepine in 12%. The synthetic route utilized steps that resulted in unstable intermediates that were difficult to isolate with the final step requiring purification twice by column chromatography. The improved synthesis reported here increased the overall yield to 30% utilizing a thiohydantoin derivative, which also facilitated the isolation of the indoloazepine. In addition, this route gave rise to new analogs of indoloazepine which were evaluated as inhibitors of Chk2.Indoloazepine was evaluated in cell culture and was found to be non-cytotoxic to cells. Indoloazepine increased survival in normal cells following IR-induced DNA damage, but not in tumor cells with mutated p53. Additionally, indoloazepine was directly inhibited Chk2 in cells by inhibition of cis-autophosphorylation of Ser516 of Chk2. Chk2 also plays a significant role in the inhibition of IR-induced G2 arrest. The data suggests that inhibition of Chk2 in normal cells protects cells exposed to IR as well as induce rapid progression into G1 so that cells initiate DNA repair following IR-induced DNA damage.
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