In summary, the present findings have demonstrated the important roles of CFTR in prostatitis and cancer development, which may provide new insight into the understanding of the prostate in health and disease. The present findings may also have potential application in diagnosis and prognosis of cancer. / In the first part of the study, the possible role and a bacterial killing mechanism involving CFTR-mediated bicarbonate secretion in prostatitis were investigated in a rat prostate model. CFTR was found to be expressed in the epithelium of rat ventral prostate. Experiments using cultured rat primary prostate epithelial cells demonstrated that CFTR was involved in mediating bicarbonate extrusion across the prostate epithelium. The expression of CFTR and carbonic anhydrase II (CAII), a key enzyme involved in cellular HCO 3- production, along with several pro-inflammatory cytokines including IL-6, IL-1beta, TNF-alpha, was significantly up-regulated in the primary culture of rat prostate epithelial cells upon E.coli-LPS challenge. Inhibition of CFTR function in vitro or in vivo resulted in reduced bacterial killing by prostate epithelial cells or the prostate. High HCO3- content (>50mM), rather than alkaline pH, was found to be responsible for bacterial killing. The direct action of HCO 3- on bacterial killing was confirmed by its ability to suppress bacterial initiation factors in E coli. The relevance of the CFTR-mediated HCO3- secretion in human was demonstrated by the upregulated expression of CFTR and CAII in human prostatitis tissues. The present results have demonstrated that CFTR plays a previously undefined role in prostatitis and could be up-regulated during the inflammation in prostate as a host defense mechanism to increase bicarbonate secretion for bacterial killing. / In the second part of the study, the possible role of CFTR in prostate cancer development and the underlying mechanisms were investigated. Our results showed that the expression of CFTR and CAII in prostate was remarkably decreased in aged rat prostate. We observed that testosterone could up-regulate the expression of CFTR and CAII in vitro and in vivo , indicating that the declined male hormones during aging may be responsible for the observed age-dependent expression of CFTR. In the present study, we found that inhibition of CFTR enhanced cell proliferation/anti-apoptosis in the prostate primary epithelial cells. CFTR was detected in all examined prostate cell lines, but with relatively higher expression levels in immortalized cell lines (PZ-HPV-7, PNT1A, PNT2C2) than in cancer cell lines (PC-3, DU-145, LNCaP). Immunohistological studies showed that the expression of CFTR was dramatically reduced in prostate cancer specimens as compared to that in normal prostate tissues. Furthermore, our gain and loss of function studies showed that knockdown of CFTR profoundly enhanced cell proliferation, cell adhesion, invasion and migration, while inhibited apoptosis in prostate cancer cell lines, overexpression of CFTR dramatically suppressed tumorigenic phenotype of cancer cells. Soft agar anchorage-independent growth assay showed that knockdown of CFTR in prostate cancer cells increased the number of colonies formed in soft agar. More importantly, we demonstrated that CFTR knockdown promoted the tumor growth in vivo and forced overexpression of CFTR in prostate cancer cells and ultrasound-mediated gene transfer of CFTR inhibited xenograft tumor growth in vivo. Mechanistically, multiple mechanisms were identified to contribute to the CFTR- mediated tumor suppressive effects. Firstly, CFTR chloride channel function was implicated in the regulation of apoptosis in prostate cancer cells. Secondly, CFTR up-regulated the transcription level of miR-34a and miR-193b, both of which have been indicated as tumor suppressors in multiple cancers. Thirdly, 11 cancer-related genes were found to be up- or down-regulated by CFTR using PCR-array. These data demonstrated that CFTR may play an important role in prostate cancer development by acting as a tumor suppressor. / The cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel conducting both Cl- and HCO3 -. It is expressed in epithelial cells of a wide variety of tissues. CFTR is also known to be expressed in human prostate; however, the physiological role of CFTR in the prostate and related diseases remains largely unknown. This thesis explored the biological roles of CFTR in prostatitis and cancer development. / Xie, Chen. / Adviser: Chan LiShaw Chang. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 175-192). / 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.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_344672 |
| Date | January 2010 |
| Contributors | Xie, Chen, Chinese University of Hong Kong Graduate School. Division of Physiology. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (xviii, 192 leaves : ill.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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