All ETDs from UAB

Advisory Committee Chair

Trygve O Tollefsbol

Advisory Committee Members

Brian Sims

Thane Wibbles

Kathleen Fischer

Yuanyuan Li

Document Type

Dissertation

Date of Award

2017

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

Colon cancer is the third most common diagnosed cancer in both women and men in the United States. It is reported that dietary factors are responsible for 70-90% of colon cancer cases. While some investigators have observed a direct correlation in high fat diets and cancer initiation, other studies have observed opposite effects mediated by fruit and vegetable consumption. Recently, studies have highlighted the importance of Epigenetics as it modifies gene expression without changing the DNA sequence. Notably, several nutritive compounds have been reported to alter epigenetic profiles in many cancer forms. SFN, an isothiocyanate found in cruciferous vegetables such as broccoli sprouts and cabbage is reported to modify many carcinogenic genes. Although SFN has been reported to act as a potent HDAC inhibitor, its ability to mediate epigenetic regulation on DNA methylation and non-coding RNAs is severely understudied. Accordingly, in this study we sought to monitor the effects of isothiocyanate SFN on the entire epigenetic network. Using easily attainable and physiologically relevant doses of SFN, we observed a SFN-mediated decrease in cell viability and cell density with a concomitant induction of apoptosis. Additionally, we also observed a significant down-regulation in HDAC1 and hTERT mRNA, protein and activity levels in CRC cells. To further test SFN’s pleotropic abilities on the epigenetic network, we measured DNA methyltransferase (DNMT) and non-coding RNA microRNA-21 (miR-21) levels in CRC cells. For the first time, we showed that physiologically relevant doses of SFN significantly down-regulated the expression of oncogenic miR-21. In addition, we also observed significant down-regulation of DNMT1 and DNMT3B protein levels, as well as regulation of global methylation levels. Interestingly we discovered that a knockdown (KD) of miR-21 resulted in a significant down-regulation of DNMT1 and DNMT3B protein and global methylation levels mediated by a significant increase in phosphatase tensin homolog deleted on chromosome ten (PTEN). Collectively, our studies provide novel findings for safe ways to mediate epigenetic therapy CRC cells.

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