Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 135-159). Also available in electronic version. Access restricted to campus users.

Barbituric acids have been historically classified as compounds that act on the central nervous system, and as such provide therapeutic uses as anxiolytics, sedatives, hypnotics, and anticonvulsants. Recent investigations of barbituric acid derivatives have provided scientists with information that barbituric acids may have applications in antibacterial, anti-chlamydial, anti-viral, as well as anti-cancer treatments. Additionally, recent literature accounts have indicated that barbituric acid derivatives may also act as immune modulators. The recent explorations of barbiturates and their potential anti-cancer and immune modulating properties are the subject of this work. Novel synthetic approaches to the development of new barbituric acid derivatives were explored thoroughly, and the mechanisms of these novel syntheses were detailed by experiment and spectroscopic characterizations. In many cases the reaction procedures were designed for large scale, efficient syntheses, that are directly applicable to pharmaceutical production of these potentially valuable therapeutic compounds. Several new products unique to barbituric acid reactions were characterized spectroscopically. Barbituric acid derivatives were the subject of biological evaluation, and the results are reported in this work. Overall, unique synthetic approaches to the production of novel barbituric acid derivatives were accomplished to create several new classes of barbiturates with potential applications in cancer treatment.

The human SRC gene encodes pp60c-Src (or c-Src), a 60 kDa, non-receptor tyrosine kinase frequently activated in colon and other tumors. Many studies have demonstrated c-Src activation can be accounted for by overexpression of c-Src protein, and that this overexpression is important for the fully transformed phenotype of cancer cells. The general goal of this thesis, therefore, was to determine the mechanism of this overexpression in human cancer cells. Examination of c-Src expression and activity in human colon cancer cell lines showed that c-Src activation was due to transcriptional activation of the SRC gene. SRC transcription is directed by the ubiquitous, Sp1 regulated SRC1A promoter, and the HNF-1alpha regulated, tissue restricted SRC1alpha promoter. To study the mechanism of SRC transcriptional activation in human cancer cell lines, a dual SRC promoter reporter construct was generated with both these promoters in their natural, physiologically linked context. Very low activity of the SRC1alpha promoter, relative to SRC1A, was consistently observed from this construct, leading to the conclusion that an enhancer element elevates SRC1alpha promoter activity. Interestingly, the HNF binding site in the SRC1alpha promoter enhanced SRC1A promoter activity in the dual promoter construct, but only in a colon cancer cell line with activated SRC. These results therefore suggest SRC transcriptional activation results from enhancer action and/or SRC promoter cross-talk in subsets of human cancer cells. <p> This study has also determined that histone deacetylase inhibitors (HDIs), compounds with documented anti-neoplastic properties, repress transcription from both SRC promoters in various cancer cell lines. To identify the mechanism of this repression, various deletion and mutant SRC promoter constructs were assayed, but HDI response elements were not identified. However, it was discovered that both promoters shared a common requirement for functional TAF1/TAF(II)250, a component of the general transcription factor TFIID. Compromised TAF1 function impaired SRC transcription, but also blocked SRC repression by HDIs. Experiments with SRC:WAF1 promoter chimeras showed the SRC promoters' TAF1 requirement could be conferred on the heterologous, TAF1-independent promoter for the WAF1 gene, which encodes the cell cycle inhibitor p21. These chimeras were also repressed by HDIs, despite WAF1 normally being strongly induced by these agents. These results therefore provide a potential functional link between promoter architecture, TAF1 dependence, and HDI mediated transcriptional repression.

The human SRC gene encodes pp60c-Src (or c-Src), a 60 kDa, non-receptor tyrosine kinase frequently activated in colon and other tumors. Many studies have demonstrated c-Src activation can be accounted for by overexpression of c-Src protein, and that this overexpression is important for the fully transformed phenotype of cancer cells. The general goal of this thesis, therefore, was to determine the mechanism of this overexpression in human cancer cells. Examination of c-Src expression and activity in human colon cancer cell lines showed that c-Src activation was due to transcriptional activation of the SRC gene. SRC transcription is directed by the ubiquitous, Sp1 regulated SRC1A promoter, and the HNF-1alpha regulated, tissue restricted SRC1alpha promoter. To study the mechanism of SRC transcriptional activation in human cancer cell lines, a dual SRC promoter reporter construct was generated with both these promoters in their natural, physiologically linked context. Very low activity of the SRC1alpha promoter, relative to SRC1A, was consistently observed from this construct, leading to the conclusion that an enhancer element elevates SRC1alpha promoter activity. Interestingly, the HNF binding site in the SRC1alpha promoter enhanced SRC1A promoter activity in the dual promoter construct, but only in a colon cancer cell line with activated SRC. These results therefore suggest SRC transcriptional activation results from enhancer action and/or SRC promoter cross-talk in subsets of human cancer cells. <p> This study has also determined that histone deacetylase inhibitors (HDIs), compounds with documented anti-neoplastic properties, repress transcription from both SRC promoters in various cancer cell lines. To identify the mechanism of this repression, various deletion and mutant SRC promoter constructs were assayed, but HDI response elements were not identified. However, it was discovered that both promoters shared a common requirement for functional TAF1/TAF(II)250, a component of the general transcription factor TFIID. Compromised TAF1 function impaired SRC transcription, but also blocked SRC repression by HDIs. Experiments with SRC:WAF1 promoter chimeras showed the SRC promoters' TAF1 requirement could be conferred on the heterologous, TAF1-independent promoter for the WAF1 gene, which encodes the cell cycle inhibitor p21. These chimeras were also repressed by HDIs, despite WAF1 normally being strongly induced by these agents. These results therefore provide a potential functional link between promoter architecture, TAF1 dependence, and HDI mediated transcriptional repression.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 90-97).

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Thesis (M. Med. Sc.)--University of Hong Kong, 2007.

Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 105-114) Also available in print.

Thesis (Ph. D. in Biochemistry)--Vanderbilt University, Aug. 2008. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 104-115).