Bcr-abl expression being associated with anti-apoptotic signaling and expression of DNA repair enzymes, we surmised that single molecules capable of blocking abl tyrosine kinase (TK) function and damaging DNA should lead to compounds with potency superior to that of GleevecRTM. To this end, we designed novel agents termed "combi-molecules" programmed to not only behave as bcr-abl inhibitors on their own, but also to further degrade to another inhibitor and a DNA damaging species. The released inhibitor was designed to sustain bcr-abl inhibition following degradation of the combi-molecule and the DNA damaging species to activate pathways leading to apoptosis. To model this strategy termed "combi-targeting", we synthesized ZRCM5 (a monoalkyltriazene) that showed antiproliferative activity superior to that of the classical DNA damaging agent TemodalRTM, but not to that of Gleevec RTM. This result was imputed to the rather weak bcr-abl inhibitory activity of ZRCM5 and its strong DNA damaging property. Another prototype designed to contain an aniline mustard moiety (AK04) was a strong bcr-abl inhibitor but a poor DNA alkylating agent. Its cytotoxic activity was again stronger than that of the clinical alkylating agent chlorambucil but inferior to that of GleevecRTM. Further chemical studies directed at structural modification of the benzamide moiety led to the synthesis of ZRF1 with strong potency against bcr-abl TK and strong DNA damaging property. This novel optimized combi-molecule showed a 1.6-3-fold greater potency than GleevecRTM against bcr-abl expressing cells. Further investigation with ZRF1, showed that its cytotoxic potency was dependent on the p53 wild-type status of the cells. In cells expressing wild-type p53, p21 transactivation was associated with cell cycle arrest and that of Bax with apoptosis. In addition to, the pro-apoptotic effect of bcr-abl inhibition, these multiple mechanisms of action may synergistically enhance the cytotoxic potency of ZRF1 in p53 wild-type cells. The study conclusively demonstrated that p53 is a major determinant for the cytotoxic advantage of the novel combi-molecular approach in chronic myelogenous leukemia (CML), a disease in which 70-85% of all cases express wild-type p53.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.111884 |
| Date | January 2007 |
| Creators | Katsoulas, Athanasia. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Division of Experimental Medicine.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002652417, proquestno: AAINR38596, Theses scanned by UMI/ProQuest. |
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