CUHK electronic theses & dissertations collection

All the results showed that TCMs can provide a source for discovering anti-angiogenic agents for the treatment of cancer, and all these experiments in the zebrafish and mammalian models further confirmed the value of zebrafish model in anti-angiogenic drug discovery.Angiogenesis refers to the formation of new blood capillaries from pre-existing ones, and is essential in a series of normal physiological processes such as embryonic development and pathological responses. However, persistent unregulated angiogenesis causes "angiogenic diseases" such as diabetic retinopathy, tumor growth and metastasis, rheumatoid arthritis, and inflammatory diseases. The linkage between angiogenesis, tumor growth and metastasis was first hypothesized by Dr. Judah Folkman in the 1970s, and now this controversial idea is widely accepted and the inhibition of angiogenesis, or anti-angiogenesis, is considered as a promising anticancer therapeutic strategy. Bevacizumab (Avastin RTM by Genentech Inc.), the first approved anti-angiogenic drug by U.S. FDA in 2004, is a humanized monoclonal antibody to inhibit endothelial cell proliferation and angiogenesis for the treatment of metastatic colorectal cancer, non-small cell lung cancer, advanced breast cancer, glioblastoma, metastatic renal cell cancer.Anti-angiogenic therapy in cancer treatment has led to the development of compounds designed to control a tumor's growth by blocking its ability to develop a blood supply. The development of agents with different mechanisms of action requires powerful preclinical models for the analysis and optimization of the therapy. Some in vitro and in vivo anti-angiogenic assays are already developed, for example, Human Umbilical Vein Endothelial Cell (HUVEC) assay, Chorioallantoic Membrane assay, Matrigel plug assay et al. Zebrafish, as a relatively new model organism, is firmly established as a powerful research platform for many areas of biology and drug discovery, allowing the testing of bioactive compounds in a whole organism and in cells undergoing normal cell-cell and cell-matrix interactions. Many anti- and pro-angiogenic molecules tested in zebrafish demonstrated similar effects to those observed in humans or other mammalian models. Besides providing a powerful platform for drug screening, zebrafish model can also be used for probing biological processes, and generate insights into mechanisms.Cancer is a generic term for a large group of diseases that can affect any part of the body, which causes a vast medical problem and is a leading cause of death worldwide nowadays. However, for many years the main methods of treating cancer have been surgery, radiotherapy and chemotherapy. Among these treatments, chemotherapy has played a major role in cancer therapy for half a century. Despite improving managements and efforts, it is not surprising that the prognosis has not greatly improved because of the limitations of current therapies, such as toxicity, inherent and acquired resistance, and metastatic spread. This calls for novel cancer therapies and new group of anticancer agents for selectively targeting cancers without or with lower toxicity to normal tissues.Traditional Chinese medicines (TCMs) have long been recognized as a rich source for discovering drugs, and various TCMs and their components have shown anti-angiogenic properties. In this thesis study, as a continuing pursuit for elucidating the anti-angiogenic properties of TCMs, our attention is focused on those with effects of anti-inflammation, anti-rheumatoid arthritis and anti-cancer. On zebrafish screening model, three of the selected TCMs, Rheum palmatum, Alpinia oxyphylla (seeds), and Kaempferia galanga showed potential anti-angiogenic activity, indicating the existence of potent anti-angiogenic components in these herbs. The ethyl acetate fraction of R. palmatum showed strong inhibition of vessel formation in zebrafish embryos. Further testing of the anthraquinones of this herb showed three of them displayed potent anti-angiogenic activities. The most potent compound---rhein could inhibit HUVEC migration and affect the mRNA expression of vegfa, kdr, angiopoietin1/2 and tie1/2; The n-hexane and ethyl acetate fractions of A. oxyphylla and K. galangal showed anti-angiogenic potentials both in zebrafish and HUVEC assays. The n-hexane and ethyl acetate fractions of A. oxyphylla could both inhibit the proliferation, migration and tube formation processes of HUVEC. And the most potential component, trans-ethyl-p-methoxycinnamate from K. galanga, could inhibit HUVEC migration and tube formation, and reduce all gene expressions involved in angiogenesis process except for vegfa.He, Zhiheng.Adviser: Wei Ge.Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: .Thesis (Ph.D.)--Chinese University of Hong Kong, 2010.Includes bibliographical references (leaves 87-108).Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.Abstract also in Chinese