TNF-alpha induced DNA damage in primary murine hepatocytes.
Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, usually arising from a background of chronic inflammatory disease. Tumor necrosis factor alpha (TNF-alpha) is a pro-inflammatory cytokine produced in response to tissue injury, endotoxin exposure or infection and TNF-alpha signalling in hepatocytes is associated with an increase in oxidative stress. DNA is vulnerable to reactive oxygen species (ROS)-induced damage, which is highly mutagenic. Cells respond to DNA damage through the stabilisation of the tumor suppressor p53, which maintains genomic fidelity through induction of a cell cycle arrest in order to allow repair or elimination of the damaged cell through apoptosis. This study was carried out to determine if TNF-alpha caused oxidative DNA damage in primary cultures of murine hepatocytes and whether any damage would result in the induction of the tumor suppressor p53 and cell-cycle arrest. Using a modified Comet assay, to measure DNA damage we have demonstrated that TNF-alpha causes the formation of 8-oxo-deoxyguanosine (8-oxodG), an established marker of oxidative DNA damage, and a lesion associated with chronic hepatitis in human livers. In addition, the increase in DNA damage did not result in p53 stabilisation and TNF-alpha caused an increase in cell-cycle progression. We believe that this study indicates a possible putative role for TNF-alpha in the early stages of malignant transformation of hepatocytes.
Wheelhouse
Nicholas M
NM
Division of Pathology, College of Medicine and Veterinary Medicine, Teviot Place, University of Edinburgh, Edinburgh EH8 9AG, Scotland, UK. n.wheelhouse@ed.ac.uk
Chan
Yuen-Sum
YS
Gillies
Sheona E
SE
Caldwell
Helen
H
Ross
James A
JA
Harrison
David J
DJ
Prost
Sandrine
S
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D004249:DNA Damage; D022781:Hepatocytes / Q000187:drug effects*; D051379:Mice; D010084:Oxidation-Reduction; D017382:Reactive Oxygen Species / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D000970:Antineoplastic Agents; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha