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Title: An Investigation into the Colorectal Cancer Chemopreventive Mechanisms of 3’, 4’, 5’, 5, 7-Pentamethoxyflavone (PMF)
Authors: Fong, Isabel Lim
Supervisors: Gescher, Andreas
Sale, Stewart
Award date: 1-Apr-2012
Presented at: University of Leicester
Abstract: 3’,4’,5’,5,7-Pentamethoxyflavone (PMF) is a naturally occurring flavone found in the leaves of Murraya paniculata and the fruits of Neoraputia magnifica. PMF has been shown to possess potential promise as a colorectal cancer (CRC) chemopreventive agent as it significantly inhibited adenoma development in the ApcMin/+ mouse, a model of gastrointestinal cancer. The chemopreventive activity of PMF was superior to that of two closely related flavone analogues apigenin and tricin. The aim of the work described in this thesis was to elucidate the mechanisms by which PMF can interfere with carcinogenesis. PMF was compared to tricin and apigenin in its abilities to inhibit growth, arrest cell cycle and elicit apoptosis in APC10.1 cells, derived from ApcMin/+ mice. Cells were incubated with these agents (10 μM, 24 h) and cDNA microarray analysis was performed to delineate changes in gene expression caused by these flavones. Gene changes were validated using reverse transcriptase-PCR and Western blot. PMF was administered to ApcMin/+ mice to assess its effects on protein expression in adenomas. PMF was the most growth-inhibitory of the three flavones with an IC50 of 5 μM. It arrested the cell cycle at G1 and G2 phases and induced a two-fold increase in apoptosis. In the microarray study PMF modulated several key signalling pathways, most notably those involving Wnt, PI3K/Akt/GSK3β and JAK/STAT. In cells in vitro PMF significantly altered expression of Wnt8b, Wnt3a, TCF4, β-catenin, GSK3β, survivin, pSTAT3 and MCM7. In mice in vivo PMF, at a dietary dose which significantly reduced adenoma development, altered only β-catenin and MCM7 protein levels. These differences were only observed in the adenomas and not the normal mucosa. GSK3β, β-Catenin and MCM7 may play a role in the CRC chemopreventive activity of PMF.
Type: Thesis
Level: Doctoral
Qualification: PhD
Rights: Copyright © the author, 2012
Appears in Collections:Theses, Dept. of Cancer Studies & Molecular Medicine
Leicester Theses

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