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Prostate Cancer Molecular Aspects to Direct Visualization Utilizing a Bioreactor

by Yates, Clayton Clopton

Abstract (Summary)
Prostate cancer is the most common cancer in males, and the second leading cause of cancer deaths in American men. Most of the mortality associated with this disease is a result of widespread dissemination of tumors cells from the primary tumor mass. In order for metastasis to occur, the cancer cell must overcome multiple barrier which include development, neovascularization, intravastion, adherence or attachment, extravasation, and ectopic growth. As dissemination from the primary tumor mass is a rate-limiting step during metastasis, tumor cells undergo an epithelial to mesenchymal transition (EMT) to acquire enhanced invasiveness and increased motility. A key step within EMT is a loss of cadherin mediated cell-cell adhesion. Unfortunately, current understanding of the regulatory mechanism of this decreased cell-cell adhesion is poorly understood. Herein this work utilizes the LHRH antagonist Cetrorelix to investigate the regulation of E-cadherin expression in invasive prostate cancer cells. We provide direct evidence that E-cadherin expression can be reinstated upon abrogation of EGFR signaling via LHRH antagonist Cetrorelix or specific inhibitors of EGFR signaling thereby limiting the invasiveness of these cells. In concert, we developed a microscale liver perfusion culture system that provides a tissue-relevant environment to assess metastasis behavior of human prostate cancer cell line DU-145 in the liver capillary bed as a model system. This system offers the currently unavailable features of real time observation of in vivo microenvironment with the manipulation of in vitro cultures. Within this system we were able to observe three dimensional growth and invasion of prostate cancer cells juxtaposed to hepatic tissue, revealing an exceptionally defined cell border at the interface of prostate cancer cells and hepatic tissue. Although not completed defined within this system, we hypothesize that exists heterotypic cell-communication between prostate cancer cells and hepatocytes. The very distinct cell border observed within our liver microreactor, coupled with our previous findings of reexpression of E-cadherin expression lead us to investigate the involvement of E-cadherin in this heterotypic communication. Consequently, prostate cancer cells utilize E-cadherin at the point of initial adherence to parenchymal hepatocytes (heterotypic interaction) and throughout the development of the metastatic tumor mass (homotypic interaction). Our observed expression pattern of E-cadherin has not been reported before. These findings constitute a new paradigm in the adhesiveness or lack there of in cancer cells during tumor invasion. The differentiation or redifferentiation (EMT) of the cancer cell during the pathophysiological events of metastasis is likely a characteristic of adaptability to the microenvironment. The term epithelial mesenchymal transition (EMT) only summates the dedifferentiation of epithelial cells to escape the primary tumor, although we have provided evidence of phenotypic reversion. Therefore we provide the impetus that Epithelial Mesenchymal Transition (EMT) should be renamed Meschenymal Epithelial reverting Transition (MErT) to underscore the dynamics of the cancer cell progression.
Bibliographical Information:

Advisor:Donna Beer-Stolz; George Michalopoulos; Cary Wu; Janey Whalen; Alan Wells

School:University of Pittsburgh

School Location:USA - Pennsylvania

Source Type:Master's Thesis

Keywords:cellular and molecular pathology

ISBN:

Date of Publication:12/16/2005

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