In order to further investigate the functions of ERRbeta/gamma in prostate cancer, the following aspects were explored in my study. My results show that: (1) Expressions of ERRbeta/gamma was down-regulated in prostate cancer cell lines and prostate cancer tissues. And only the short-form but not other ERRbeta isoforms was expressed in prostatic cells. (2) Overexpression of ERRbeta/gamma significantly inhibited the cell proliferation in vivo and in vitro. (3) Cell cycle analysis showed that S-phase fraction of ERRbeta/gamma stable clones was significantly decreased, while there was no significantly induced apoptosis by ERRbeta/gamma overexpression. This was confirmed by BrdU incorporation assay. (4) Expressions of two cyclin-CDK inhibitors p21Cip1/Waf1 and p27Kip1 were increased significantly in ERRgamma clones, but only p21 in ERRbeta clones. (5) P21 and p27 gene promoters could be transactived by ERRgamma, but only p21 by ERRbeta. The transactivity of p21 by ERRbeta can be potently enhanced by PGC-1alpha (6) Deletion mutants of ERRgamma showed the transaction of p21 required an intact DNA-binding domain. (7) DY131, the ERRbeta/gamma agonist, further potentiated the growth inhibition in ERRbeta/gamma-stable clones in a dose-dependent manner. (8) There were increase in number of giant potential-active mitochondria and accumulation of lipid droplets in ERRbeta-clones. / Prostate cancer is the most common diagnosed cancers in men in western countries. Despite the substantial clinical significance, the mechanisms underlying the development and progression of prostate cancer are poorly understood. ERRs(alpha, beta, gamma) belong to orphan nuclear. All ERR subtypes share significant homology with estrogen receptors (ERs) in their protein structures. Functionally ERRalpha shares, regulates same target genes with ERalpha and is involved in carcinogenesis, while the ERRbeta and ERRgamma are still unknown. / The results obtained indicate that ERRbeta/gamma inhibit proliferation of prostate cancer cells by arresting of cell cycle progression, suggesting a tumor suppressor function for ERRbeta/gamma in prostate cancer. p21 may be the key mediator of this suppressor function, and the p21 is the target gene of ERRbeta/gamma. The selective ERRbeta/gamma agonist, DY131, potently inhibited the proliferation of ERRbeta/gamma-positive prostate cancer cells, suggesting ERRbeta and gamma could be a potential therapeutic target for prostate cancer therapy. / Yu, Shan. / "July 2007." / Adviser: Franky L. Chan. / Source: Dissertation Abstracts International, Volume: 69-01, Section: B, page: 0238. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 140-165). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Overexpression of the epidermal growth factor receptor (EGFR), a member of the ErbB family, and its closest homologue HER2, have been associated with aggressive tumour progression and reduced sensitivity to DNA-damaging agents. In order to block the proliferation of refractory tumors overexpressing EGFR, a novel strategy has been developed that sought to design molecules capable of not only blocking EGFR-TK, but also damaging DNA. These molecules, termed combi-molecules (CMs), have been shown to degrade under physical conditions to release another inhibitor of EGFR, and to be potent against tumor cells of various origins including breast, prostate and carcinoma of the vulva. However, despite their potency, their growth inhibitory IC50 values were still in the high micromolar range. In order to augment the potency of the CMs, here they were re-designed to contain two quinazoline moieties and a central N,N-bis(2-aminoethyl)methylamine spacer which, following degradation, could yield higher concentrations of free inhibitors and a more cytotoxic bifunctional DNA damaging species. Here, we describe the mechanism of action of the first prototype of this approach, JDE52, which we now classify as a double-arm CM, in comparison with ZRBA1, its closest single-arm counterpart. The results indicated that JDE52 was capable of inducing significant blockade of EGFR, DNA single-strand breaks and inter-strand cross-links. ZRBA1, its single-arm counterpart, was capable of only forming DNA single-strand breaks. The fluorescent property of FD105, the secondary inhibitor that both JDE52 and ZRBA1 are capable of releasing, has permitted the analysis of its levels in tumor cells by UV flowcytometry. It was found that JDE52 was indeed capable of significantly releasing higher levels of fluorescence (p<0.05) in human tumor cells, compared with levels of fluorescence released by ZRBA1. More importantly, JDE52 induced higher levels of apoptosis and cell killing than ZRBA1. Apoptosis was triggered by JDE52 at a faster rate than ZRBA1. The results in toto suggest that the superior potency of JDE52, when compared with ZRBA1, may be imputed to mechanisms associated with the generation of higher levels of FD105 intracellularly, and the induction of DNA cross-links, which are known to be more cytotoxic. These combined mechanisms (blockade of EGFR-TK and formation of cross-links) contributed to an accelerated rate of apoptosis in cells treated with JDE52. This study conclusively demonstrated that designing molecules as prodrugs of high levels of quinazoline inhibitors of EGFR and bifunctional DNA cross-linking species is a valid strategy to enhance the potency of CMs against refractory tumors.

The process of metastasis is initiated through the acquisition of inherent and autonomous motile and invasive properties by tumor cells. These phenomena are initiated through a balance between forward cancer cell membrane protrusion and tail retraction, and occur via cell cytoskeleton remodeling, actin reorganization, and coordinated focal adhesion assembly and disassembly events. Among the vast network of cytoskeletal proteins, the actin-bundling protein fascin plays a major function in cell cytoskeleton remodeling. It is a 55-kDa protein involved in the formation of filopodia and cell migration, and found to be upregulated in many cancers. We report herein key functions for fascin in the regulation of prostate and breast cancer progression. Fascin expression is upregulated in localized and hormone refractory prostate cancer, responsible for a more aggressive clinical course. In addition, functional dissection of fascin reveals a novel function in the regulation of focal adhesion turnover dynamics, by modulating the phosphorylation state of central focal adhesion proteins through a potential collaboration with the protein tyrosine phosphatase, PEST. Together, our data support the importance of fascin in cancer cell invasion and as a significant prognostic marker and a potential therapeutic target for aggressive cancers.

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