Investigating the role of heme oxygenase and oxidative stress in oesophagogastric cancer
File(s)
Author(s)
Priest, Oliver
Type
Thesis
Abstract
Background: Molecular mechanisms underlying gastric and oesophageal cancer include alterations in growth factors, cytokines and cell adhesion molecules. Heme oxygenase (HO) enzyme catalyses the degradation of heme and generates bilirubin and carbon monoxide that have antioxidant, anti-inflammatory and anti-apoptotic activities. HO enzyme is implicated in the biology of cancer by its effects on cell growth and resistance to apoptosis. The roles of HO-1 and HO-2 enzymes in cancer cell growth are poorly understood, with reports suggesting both anti-inflammatory, anti-tumour effects and tumour-protective mechanisms mediated by HO activity. The role of HO-2 in inflammation and cancer is largely unexplored. Further understanding the influence of the HO enzyme system may provide improved novel targets for oesophagogastric cancer therapy.
Materials and Methods: The primary objective of the thesis was to characterise the role of the heme oxygenase pathway and modulation of HO activity in upper gastrointestinal cancer cell growth in vitro. Cell culture techniques included MTT growth assay, Western blotting protein analysis, pharmacological modulation of HO activity and targeted knockdown of HO mRNA. Apoptosis was studied with flow cytometry techniques. Enzymatic HO activity was measured by specific colorimetric assay.
Results: Results showed that specific knockdown of HO-2 protein activity with induction of HO-1 enzyme caused a reduction in oesophageal and gastric cancer cell growth with cell cycle effects and an increase in apoptosis. Treatment with downstream products of HO activity carbon monoxide and bilirubin and the anti-inflammatory agent N-acetyl cysteine had similar effects and increased the response of cancer cells to chemotherapeutic agents.
Conclusion: These studies further our understanding of the role of heme oxygenase in cancer, providing evidence that modification of HO activity in oesophagogastric cancer cells leads to reduced cell proliferation. The findings support future potential clinical applications of carbon monoxide therapy that require further experimental animal model and clinical studies in the context of oesophagogastric cancer.
Materials and Methods: The primary objective of the thesis was to characterise the role of the heme oxygenase pathway and modulation of HO activity in upper gastrointestinal cancer cell growth in vitro. Cell culture techniques included MTT growth assay, Western blotting protein analysis, pharmacological modulation of HO activity and targeted knockdown of HO mRNA. Apoptosis was studied with flow cytometry techniques. Enzymatic HO activity was measured by specific colorimetric assay.
Results: Results showed that specific knockdown of HO-2 protein activity with induction of HO-1 enzyme caused a reduction in oesophageal and gastric cancer cell growth with cell cycle effects and an increase in apoptosis. Treatment with downstream products of HO activity carbon monoxide and bilirubin and the anti-inflammatory agent N-acetyl cysteine had similar effects and increased the response of cancer cells to chemotherapeutic agents.
Conclusion: These studies further our understanding of the role of heme oxygenase in cancer, providing evidence that modification of HO activity in oesophagogastric cancer cells leads to reduced cell proliferation. The findings support future potential clinical applications of carbon monoxide therapy that require further experimental animal model and clinical studies in the context of oesophagogastric cancer.
Version
Open Access
Date Issued
2013-10
Date Awarded
2014-07
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Hanna, George
Sponsor
European Union
Grant Number
BAMOD LSHC-CT-2005-019031
Publisher Department
Surgery & Cancer
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)