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DNA damage-induced sustained p53 activation contributes to inflammation-associated hepatocarcinogenesis in rats.

ABSTRACT: The tumor suppressor p53 has an important role in inducing cell-intrinsic responses to DNA damage, including cellular senescence or apoptosis, which act to thwart tumor development. It has been shown, however, that senescent or dying cells are capable of eliciting inflammatory responses, which can have pro-tumorigenic effects. Whether DNA damage-induced p53 activity can contribute to senescence- or apoptosis-associated pro-tumorigenic inflammation is unknown. Recently, we generated a p53 knock-out rat via homologous recombination in rat embryonic stem cells. Here we show that in a rat model of inflammation-associated hepatocarcinogenesis, heterozygous deficiency of p53 resulted in attenuated inflammatory responses and ameliorated hepatic cirrhosis and tumorigenesis. Chronic administration of hepatocarcinogenic compound, diethylnitrosamine, led to persistent DNA damage and sustained induction of p53 protein in the wild-type livers, and much less induction in p53 heterozygous livers. Sustained p53 activation subsequent to DNA damage was accompanied by apoptotic rather than senescent hepatic injury, which gave rise to the hepatic inflammatory responses. In contrast, the non-hepatocarcinogenic agent, carbon tetrachloride, failed to induce p53, and caused a similar degree of chronic hepatic inflammation and cirrhosis in wild type and p53 heterozygous rats. These results suggest that although p53 is usually regarded as a tumor suppressor, its constant activation can promote pro-tumorigenic inflammation, especially in livers exposed to agents that inflict lasting mutagenic DNA damage.

SUBMITTER: Yan HX

PROVIDER: S-EPMC3855850 | biostudies-literature | 2013 Sep

REPOSITORIES: biostudies-literature

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DNA damage-induced sustained p53 activation contributes to inflammation-associated hepatocarcinogenesis in rats.

Yan H-X HX Wu H-P HP Zhang H-L HL Ashton C C Tong C C Wu J J Qian Q-J QJ Wang H-Y HY Ying Q-L QL

Oncogene 20121015 38

The tumor suppressor p53 has an important role in inducing cell-intrinsic responses to DNA damage, including cellular senescence or apoptosis, which act to thwart tumor development. It has been shown, however, that senescent or dying cells are capable of eliciting inflammatory responses, which can have pro-tumorigenic effects. Whether DNA damage-induced p53 activity can contribute to senescence- or apoptosis-associated pro-tumorigenic inflammation is unknown. Recently, we generated a p53 knock-o ...[more]

PMID: 23069657

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Project description:Surgical resection is the preferred treatment for Hepatocellular carcinoma; however, it induces tumor recurrence. Our objective was to understand the molecular mechanisms linking liver regeneration under chronic-inflammation to tumorigenesis. Mdr2-knockout mice, a model of inflammation-associated cancer, underwent partial-hepatectomy which led to enhanced hepatocarcinogenesis. Yet, liver regeneration in these mice was severely attenuated. We demonstrate the activation of the DNA damage response machinery and altered genomic instability during early liver inflammatory stages resulting in hepatocyte apoptosis and cell-cycle arrest, and suggest their involvement in tumor recurrence subsequent to partial hepatectomy. We propose that under the regenerative proliferative stress induced by liver resection, the genomic unstable hepatocytes generated during chronic-inflammation, escape apoptosis and reenter the cell-cycle, triggering the enhanced tumorigenesis At present, there is a great organ shortage worldwide, thus the main treatment for Hepatocellular carcinoma (HCC) is liver resection. However, liver resection induces recurrence and mortality. In our study, we decipher, for the first time, the contribution of the DNA damage response in HCC development and recurrence, the immediate and long term effect. This is an important finding regarding the association between carcinogenesis and DNA damage response. Additionally, we demonstrate yet another link between inflammation, inducing DNA damage and genome instability, and carcinogenesis that has not been explored in the past. These results may assist in developing treatments that will reduce tumor recurrence and additionally, new prophylactic therapies during early inflammatory stages. Keywords: time course, regeneration RNA was isolated from liver samples of 9-month-old Mdr2-/- and control mice obtained on days 0 (the removed lobe), 2 and 6 following PHx. Samples of d0 were obtained from the same mice that were sacrificed on later days. As we were concerned by the variability in the KO group 6 samples were obtained for d0. All other time points and groups contained 3 samples each.

Dataset Information

DNA damage-induced sustained p53 activation contributes to inflammation-associated hepatocarcinogenesis in rats.

Publications

DNA damage-induced sustained p53 activation contributes to inflammation-associated hepatocarcinogenesis in rats.

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