Date of Award

2017

Document Type

Open Access Master's Thesis

Degree Name

Doctor of Philosophy in Biochemistry and Molecular Biology (PhD)

Administrative Home Department

Department of Biological Sciences

Advisor 1

Guiliang Tang

Committee Member 1

Xiaoqing Tang

Committee Member 2

Rupali Datta

Committee Member 3

Tarun Dam

Abstract

The main aim of this study was to investigate the effects of Portulaca oleracea extract on tumor formation in colon cancer stem cells and chemotherapy sensitivity. In addition, this study analyzed the genetic changes within the Notch signal transduction pathway associated with the effects of the extracts. Serum-free cultures of colon cancer cells (HT-29) and HT-29 stem cells were treated with the chemotherapeutic drug 5-FU to assess sensitivity. Injections of the stem cells were also given to BALB/c mice to confirm tumor growth and characteristics. In addition, the effect of different concentrations of P. oleracea extract was tested on the growth of HT-29 and HT-29 stem cells, which was determined by the MTT method. The effects of P. oleracea extract on the expression of β-catenin, Notch1, and Notch2 in HT-29 cells were detected by RT-PCR and Western blotting. The tumor volume of HT29 cells was two times larger than that of HT29 stem cells. Treatment with P. oleracea extracts inhibited the proliferation of both HT-29 and HT-29 stem cells in doses from 0.07 - 2.25 μg/mL. Apoptosis of HT-29 and HT-29 stem cells, as assessed by flow cytometry, was enhanced by the addition of P. oleracea extract. Finally, treatment with P. oleracea extracts significantly down-regulated the expression of the Notch1 and β-catenin genes in both cell types.