Date of Award

2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biochemistry and Molecular Biology

College

College of Graduate Studies

First Advisor

Daniel J. Fernandes

Second Advisor

Nigel Courtenay

Third Advisor

Eleanor Spicer

Fourth Advisor

Anthony J. Alberg

Fifth Advisor

Katherine R. Sterba

Abstract

A growing body of scientific evidence has demonstrated that chronic psychological stress can not only increase the growth and metastasis of tumors through a number of mechanisms, such as by an increase of VEGF and Bcl-2, but also can decrease the survival of cancer patients. However, no studies have reported the effect of psychological stress with respect to the tumor marker MUC1. Therefore, building upon previous research, the purpose of the present study was to investigate the effect of the stress hormones cortisol and norepinephrine on the tumor marker MUC1, which is highly associated with tumor cell metastasis and is aberrantly glycosylated in most human epithelial carcinomas. Thus, it has been widely used in clinics as an important prognostic marker of disease progression and response to treatment. Overexpression of MUC1 in prostate cancer has been associated with more aggressive disease and an increased risk of recurrence. Using the DU-145 prostate cancer cell line as an experimental model, we sought to determine whether the glucocorticoid cortisol and the catecholamine norepinephrine enhanced the expression of MUC1 at the transcriptional and protein levels, and whether increased MUC1 altered the invasive potential of DU-145 cells. The levels of MUC1 protein expression were assayed by ELISA, flow cytometry, and the colorimetric bradford assay. The mRNA levels of MUC1 were measured by RT-PCR. In addition, cell invasiveness and migration were assayed by the matrigel migration assay. The results indicate that physiologically relevant concentrations of cortisol found in tumor microenvironment (10[superscript -7] M) enhanced the expression of MUC1 by approximately 2-fold after 6 or 10 days of treatment as assayed by ELISA. In addition, flow cytometric analyses revealed that DU-145 cells treated for 3 or 6 days with cortisol up-regulated the cell-surface expression of MUC1 by approximately 2-fold, whereas a 10 day exposure up-regulated the expression by 7-fold. Norepinephrine alone did not alter the expression of MUC1 at any time point in any of the experiments. In addition to these elevated levels of MUC1 protein, the mRNA levels of MUC1 were increased by 6-fold when cells were treated with cortisol for 6 days and by 4-fold when cells were treated for 10 days, while norepinephrine had no effect on mRNA levels. In addition, the matrigel migration assay indicated that cells treated with cortisol for 6-10 days migrated faster through the membrane as compared to untreated cells. Together, data generated from this thesis provide novel evidence of a biochemical link between the glucocorticoid cortisol, a hormonal mediator of psychological stress, and increased levels of the tumor marker MUC 1. Findings arising from this thesis raise the possibility that in prostate cancer the interaction of MUC1 with stress hormones, such as cortisol may increase the expression of MUC1 resulting in the observed increase in disease in psychologically stressed individuals. These novel findings highlight the necessity for future studies designed to investigate further the relationship between hormonal mediators of psychological stress and increased levels of MUC1.

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