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- All Subjects: Bleomycin
- Creators: Bozeman, Trevor C
- Creators: Paul, Rakesh
Description
The bleomycins are a family of glycopeptide-derived antibiotics isolated from various Streptomyces species and have been the subject of much attention from the scientific community as a consequence of their antitumor activity. Bleomycin clinically and is an integral part of a number of combination chemotherapy regimens. It has previously been shown that bleomycin has the ability to selectively target tumor cells over their non-malignant counterparts. Pyrimidoblamic acid, the N-terminal metal ion binding domain of bleomycin is known to be the moiety that is responsible for O2 activation and the subsequent chemistry leading to DNA strand scission and overall antitumor activity. Chapter 1 describes bleomycin and related DNA targeting antitumor agents as well as the specific structural domains of bleomycin. Various structural analogues of pyrimidoblamic acid were synthesized and subsequently incorporated into their corresponding full deglycoBLM A6 derivatives by utilizing a solid support. Their activity was measured using a pSP64 DNA plasmid relaxation assay and is summarized in Chapter 2. The specifics of bleomycin—DNA interaction and kinetics were studied via surface plasmon resonance and are presented in Chapter 3. By utilizing carefully selected 64-nucleotide DNA hairpins with variable 16-mer regions whose sequences showed strong binding in past selection studies, a kinetic profile was obtained for several BLMs for the first time since bleomycin was discovered in 1966. The disaccharide moiety of bleomycin has been previously shown to be a specific tumor cell targeting element comprised of L-gulose-D-mannose, especially between MCF-7 (breast cancer cells) and MCF-10A ("normal" breast cells). This phenomenon was further investigated via fluorescence microscopy using multiple cancerous cell lines with matched "normal" counterparts and is fully described in Chapter 4.
ContributorsBozeman, Trevor C (Author) / Hecht, Sidney M. (Thesis advisor) / Chaput, John (Committee member) / Gould, Ian (Committee member) / Arizona State University (Publisher)
Created2013
Description
ABSTRACT Manipulation of biological targets using synthetic or naturally occurring organic compounds has been the focal point of medicinal chemistry. The work described herein centers on the synthesis of organic small molecules that are targeted either to cell surface receptors, to the ribosomal catalytic center or to human immunodeficiency virus reverse transcriptase. Bleomycins (BLMs) are a family of naturally occurring glycopeptidic antitumor agents with an inherent selectivity towards cancer cells. DeglycoBLM, which lacks the sugar moiety of bleomycin, has much lower cytotoxicity in cellular assays. A recent study using microbbuble conjugates of BLM and deglycoBLM showed that BLM was able to selectively bind to breast cancer cells, whereas the deglyco analogue was unable to target either the cancer or normal cells. This prompted us to further investigate the role of the carbohydrate moiety in bleomycin. Fluorescent conjugates of BLM, deglycoBLM and the BLM carbohydrate were studied for their ability to target cancer cells. Work presented here describes the synthesis of the fluorescent carbohydrate conjugate. Cell culture assays showed that the sugar moiety was able to selectively target various cancer cells. A second conjugate was prepared to study the importance of the C-3 carbamoyl group present on the mannose residue of the carbohydrate. Three additional fluorescent probes were prepared to improve the uptake of this carbohydrate moiety into cancer cells. Encouraged by the results from the fluorescence experiments, the sugar moiety was conjugated to a cytotoxic molecule to selectively deliver this drug into cancer cells. The nonsense codon suppression technique has enabled researchers to site specifically incorporate noncanonical amino acids into proteins. The amino acids successfully incorporated this way are mostly α-L-amino acids. The non-α-L-amino acids are not utilized as substrates by ribosome catalytic center. Hoping that mutations near the ribosome peptidyltransferase site might alleviate its bias towards α-L-amino acids, a library of modified ribosomes was generated. Analogues of the naturally occurring antibiotic puromycin were used to select promising candidates that would allow incorporation of non-α-L-amino acids into proteins. Syntheses of three different puromycin analogues are described here. The reverse transcriptase enzyme from HIV-1 (HIV-1 RT) has been a popular target of HIV therapeutic agents due to its crucial role in viral replication. The 4-chlorophenyl hydrazone of mesoxalic acid (CPHM) was identified in a screen designed to find inhibitors of strand transfer reactions catalyzed by HIV-1 RT. Our collaborators designed several analogues of CPHM with different substituents on the aromatic ring using molecular docking simulations. Work presented here describes the synthesis of eight different analogues of CPHM.
ContributorsPaul, Rakesh (Author) / Hecht, Sidney M. (Thesis advisor) / Moore, Ana L (Committee member) / Rose, Seth D (Committee member) / Arizona State University (Publisher)
Created2013