Date of Award

2017

Document Type

Open Access Thesis

Department

Biomedical Science

Sub-Department

School of Medicine

First Advisor

Swapan Ray

Abstract

Glioblastoma multiforme (GBM), or simply glioblastoma, is the most common and aggressive primary brain tumor, with a prevalence of approximately 20,000 new cases per year in the United States and a 3-year survival rate of just 2%. Quercetin (QCT) is a dietary flavonoid that can be found in common foods such as red kidney beans, cilantro, and onions. Despite little evidence showing any benefits through dietary intake of QCT, various studies show its promising anti-cancer results in vitro. In glioblastoma, QCT is able to cause significant amounts of apoptosis through a variety of mechanisms. These include activation of caspase-9 and caspase-3, deactivation of matrix metalloprotease-2 (MMP-2), inhibition of heat-shock protein-27 (HSP-27) and HSP-72, and increased p53 activity. Autophagy is a natural occurring survival mechanism that is induced when cells are subjected to environmental stressors like nutrient deprivation, high heat, or hypoxia. As a result, many synergistic studies are being performed with QCT in order to find out adequate autophagy down regulation that could complement QCT for enhancing its apoptosis inducing capabilities. Synergism is the concept of two substances providing a greater affect than the sum of their individual affects. Drugs acting in synergism with each other is a promising investigative avenue for many alternative cancer treatments, including GBM.

The drugs QCT and Sodium Butyrate (NaB) were investigated under autophagic conditions in three GBM cell lines in order to test their efficacy in slowing the growth of glioblastoma cells in-vitro due to the reduction of autophagy. The three glioblastoma cell lines tested are C6 (rat), T98G (human), and LN18 (human). The results of this study showed a marked increase in apoptosis in all three GBM cell lines, with the most occurring in T98G. Apoptosis levels were determined via Wright Staining and Annexin V/PI staining. QCT + NaB combination treatments were also found to reduce serum-starved induced autophagy in all cell lines with the most prominent occurring in T98G. QCT alone was also found to be an autophagy inhibitor at a 25 μM concentration. These results were confirmed via acridine orange staining and western blotting. QCT + NaB was also found to act in synergism to reduce poly (ADP-ribose) polymerase-1 (PARP-1), a DNA repair enzyme, and survivin, an anti-apoptotic protein, expression in C6 cells, which further confirmed the potential efficacy of QCT + NaB to be used in conjunction with conventional chemotherapeutic therapies.

Rights

© 2017, Matthew Alan Taylor

Download

Share

COinS