Matching Items (5)
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- All Subjects: Antineoplastic agents
- Creators: Hecht, Sidney M.
- Creators: Bozeman, Trevor C
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
The communication of genetic material with biomolecules has been a major interest in cancer biology research for decades. Among its different levels of involvement, DNA is known to be a target of several antitumor agents. Additionally, tissue specific interaction between macromolecules such as proteins and structurally important regions of DNA has been reported to define the onset of certain types of cancers.
Illustrated in Chapter 1 is the general history of research on the interaction of DNA and anticancer drugs, most importantly different congener of bleomycin (BLM). Additionally, several synthetic analogues of bleomycin, including the structural components and functionalities, are discussed.
Chapter 2 describes a new approach to study the double-strand DNA lesion caused by antitumor drug bleomycin. The hairpin DNA library used in this study displays numerous cleavage sites demonstrating the versatility of bleomycin interaction with DNA. Interestingly, some of those cleavage sites suggest a novel mechanism of bleomycin interaction, which has not been reported before.
Cytidine methylation has generally been found to decrease site-specific cleavage of DNA by BLM, possibly due to structural change and subsequent reduced bleomycin-mediated recognition of DNA. As illustrated in Chapter 3, three hairpin DNAs known to be strongly bound by bleomycin, and their methylated counterparts, were used to study the dynamics of bleomycin-induced degradation of DNAs in cancer cells. Interestingly, cytidine methylation on one of the DNAs has also shown a major shift in the intensity of bleomycin induced double-strand DNA cleavage pattern, which is known to be a more potent form of bleomycin induced cleavages.
DNA secondary structures are known to play important roles in gene regulation. Chapter 4 demonstrates a structural change of the BCL2 promoter element as a result of its dynamic interaction with the individual domains of hnRNP LL, which is essential to facilitate the transcription of BCL2. Furthermore, an in vitro protein synthesis technique has been employed to study the dynamic interaction between protein domains and the i-motif DNA within the promoter element. Several constructs were made involving replacement of a single amino acid with a fluorescent analogue, and these were used to study FRET between domain 1 and the i-motif, the later of which harbored a fluorescent acceptor nucleotide analogue.
Illustrated in Chapter 1 is the general history of research on the interaction of DNA and anticancer drugs, most importantly different congener of bleomycin (BLM). Additionally, several synthetic analogues of bleomycin, including the structural components and functionalities, are discussed.
Chapter 2 describes a new approach to study the double-strand DNA lesion caused by antitumor drug bleomycin. The hairpin DNA library used in this study displays numerous cleavage sites demonstrating the versatility of bleomycin interaction with DNA. Interestingly, some of those cleavage sites suggest a novel mechanism of bleomycin interaction, which has not been reported before.
Cytidine methylation has generally been found to decrease site-specific cleavage of DNA by BLM, possibly due to structural change and subsequent reduced bleomycin-mediated recognition of DNA. As illustrated in Chapter 3, three hairpin DNAs known to be strongly bound by bleomycin, and their methylated counterparts, were used to study the dynamics of bleomycin-induced degradation of DNAs in cancer cells. Interestingly, cytidine methylation on one of the DNAs has also shown a major shift in the intensity of bleomycin induced double-strand DNA cleavage pattern, which is known to be a more potent form of bleomycin induced cleavages.
DNA secondary structures are known to play important roles in gene regulation. Chapter 4 demonstrates a structural change of the BCL2 promoter element as a result of its dynamic interaction with the individual domains of hnRNP LL, which is essential to facilitate the transcription of BCL2. Furthermore, an in vitro protein synthesis technique has been employed to study the dynamic interaction between protein domains and the i-motif DNA within the promoter element. Several constructs were made involving replacement of a single amino acid with a fluorescent analogue, and these were used to study FRET between domain 1 and the i-motif, the later of which harbored a fluorescent acceptor nucleotide analogue.
ContributorsRoy, Basab (Author) / Hecht, Sidney M. (Thesis advisor) / Jones, Anne (Committee member) / Levitus, Marcia (Committee member) / Chaput, John (Committee member) / Arizona State University (Publisher)
Created2014
Description
Cellular redox phenomena are essential for the life of organisms. Described here is a summary of the synthesis of a number of redox-cycling therapeutic agents. The work centers on the synthesis of antitumor antibiotic bleomycin congeners. In addition, the synthesis of pyridinol analogues of alpha-tocopherol is also described. The bleomycins (BLMs) are a group of glycopeptide antibiotics that have been used clinically to treat several types of cancers. The antitumor activity of BLM is thought to be related to its degradation of DNA, and possibly RNA. Previous studies have indicated that the methylvalerate subunit of bleomycin plays an important role in facilitating DNA cleavage by bleomycin and deglycobleomycin. A series of methylvalerate analogues have been synthesized and incorporated into deglycobleomycin congeners by the use of solid-phase synthesis. All of the deglycobleomycin analogues were found to effect the relaxation of plasmid DNA. Those analogues having aromatic C4-substituents exhibited cleavage efficiency comparable to that of deglycoBLM A5. Some, but not all, of the deglycoBLM analogues were also capable of mediating sequence-selective DNA cleavage. The second project focused on the synthesis of bicyclic pyridinol analogues of alpha-tocopherol. Bicyclic pyridinol antioxidants have recently been reported to suppress the autoxidation of methyl linoleate more effectively than alpha-tocopherol. However, the complexity of the synthetic routes has hampered their further development as therapeutic agents. Described herein is a concise synthesis of two bicyclic pridinol antioxidants and a facile approach to their derivatives with simple alkyl chains attached to the antioxidant core. These analogues were shown to retain biological activity and exhibit tocopherol-like behaviour.
ContributorsCai, Xiaoqing (Author) / Hecht, Sidney M. (Thesis advisor) / Gould, Ian R (Committee member) / Hartnett, Hilairy E (Committee member) / Arizona State University (Publisher)
Created2011
Description
Natural products that target the DNA of cancer cells have been an important source of knowledge and understanding in the development of anticancer chemotherapeutic agents. Bleomycin (BLM) exemplifies this class of DNA damaging agent. The ability of BLM to chelate metal ions and effect oxidative damage of the deoxyribose sugar moiety of DNA has been studied extensively for four decades. Here, the study of BLM A5 was conducted using a previously isolated library of hairpin DNAs found to bind strongly to metal free BLM. The ability of BLM to effect single-stranded was then extensively characterized on both the 3′ and 5′-arms of the hairpin DNAs. The strongly bound DNAs were found to be efficient substrates for Fe·BLM A5-mediated cleavage. Surprisingly, the most prevalent site of damage by BLM was found to be a 5′-AT-3′ dinucleotide sequence. This dinucleotide sequence and others generally not cleaved by BLM when examined using arbitrarily chosen DNA substrate were found in examining the library of ten hairpin DNAs. In total, 111 sites of DNA damage were found to be produced by exposure of the hairpin DNA library to Fe·BLM A5. Also, an assay was developed with which to test the propensity of the hairpin DNAs to undergo double stranded DNA damage. Adapting methods previously described by the Povirk laboratory, one hairpin was characterized using this method. The results were in accordance with those previously reported.
ContributorsSegerman, Zachary (Author) / Hecht, Sidney M. (Thesis advisor) / Levitus, Marcia (Committee member) / Ghirlanda, Giovanna (Committee member) / Arizona State University (Publisher)
Created2011
Description
Many natural and synthetic quinones have shown biological and pharmacological activity. Some of them have also shown anticancer activity. Ubiquinone (CoQ10) which is a natural quinone, is a component of the electron transport chain and participates in generation of ATP (adenosine triphosphate). Cellular oxidative stress is key feature of many neurodegenerative diseases such as Friedreich's ataxia, Alzheimer's disease and Parkinson's disease. The increased generation of reactive oxygen species damages cell membranes and leads to cell death. Analogues of ubiquinone in the form of pyrimidinols and pyridinols, were effective in protecting Friedreich's ataxia lymphocytes from oxidative stress- induced cell death. There were some structural features which could be identified that should be useful for the design of the analogues for cellular protection against oxidative stress. There are quinones such as doxorubicin, daunomycin and topopyrones which have anticancer activity. Here I evaluated topopyrone analogues which poison both topoisomerases I and II. The topopyrone analogues were lethal to human breast cancer cells, but these analogues were not as potent as camptothecin.
ContributorsRaghav, Nidhi (Author) / Hecht, Sidney M. (Thesis advisor) / Gould, Ian R (Committee member) / Williams, Peter (Committee member) / Arizona State University (Publisher)
Created2011