| In January 2005, the American Cancer Society declared cancer as the top killer of Americans under the age of 85. Estimates predict that during the next twenty years, deaths from cancer worldwide could nearly double. Chemotherapy, or the use of drugs, plays a role in improving the survival and quality of life for cancer patients in addition to providing effective treatment for a majority of human cancers and a curative treatment for some cancers.; The following dissertation presents a collection of four studies in which cellular, molecular, and synthetic approaches were used for the discovery and understanding of cancer and chemotherapeutic agents. Chapter One comprehensively reviews the literature to date, describing core concepts relevant to the different projects. Chapter Two comprises a study in which resistance was developed in NCI-H460 lung carcinoma against anti-tubulin, anti-cancer agents associated with three unique tubulin binding sites: combretastatin A-4, paclitaxel, or vinblastine. The results demonstrated altered beta-tubulin isotype expression levels in the resistant cell lines and revealed that the microtubule depolymerizers, combretastatin A-4 and vinblastine, induced similar isotype alterations, while the microtubule polymerizer, paclitaxel, induced different alterations. In Chapter Three, synthetic methodologies were applied to design and prepare novel bridge-modified combretastatin A-4 and A-1 analogs as potential tubulin-binding and vascular-targeting agents. The structure-activity relationship of these compounds has been studied by in vitro and in vivo assays. Chapter Four, describes the genetic engineering of alpha-tubulin, beta III-tubulin, and green fluorescent protein genes into tobacco mosaic virus-based vectors and the study of the expression of the corresponding recombinant proteins in the tobacco, Nicotiana benthamiana. The last project chapter, Chapter Five, demonstrates synergy in the MOLT-4 leukemia cell line with exposure to chemotherapeutic agents cordycepin and hydroxyurea in combination; the results support the theory that cordycepin functions as a chain terminating substrate analog with TdT polymerase.; In conclusion, a wide range of methodologies were utilized, with specific projects involving the cellular and molecular characterization of cancer drug-resistance, the synthetic preparation of small molecules as potential cancer therapeutics, the production of recombinant proteins by molecular biology techniques, and the evaluation of combination drug exposure in cancer treatment. |
