p53 induction as a genotoxic test for twenty-five chemicals undergoing in vivo carcinogenicity testing.

Abstract

In vivo carcinogenicity testing is an expensive and time-consuming process, and as a result, only a relatively small fraction of new and existing chemicals has been tested in this manner. Therefore, the development and validation of alternative approaches is desirable. We previously developed a mammalian in vitro assay for genotoxicity based on the ability of cells to increase their level of the tumor-suppressor protein p53 in response to DNA damage. Cultured (11,16,17) or by initiating a cell's apoptotic pathway (18)(19)(20)(21).The assay itself is simple (9). Cultured mammalian cells (NCTC 929) are treated with various doses of the test agent, and at specified time points following treatment, the cells are harvested and lysed. The level of p53 in the lysates is measured by p53 enzymelinked immunosorbent assay (ELISA) and/or Western blot analysis, and compared to the level in untreated cells.Our previous work (9) indicated that both Western blot and ELISA analyses yielded similar results. Therefore, our current work focused on the more quantitative ELISA assay. We also found that the NCTC 929 cell line was a useful model system. NCTC 929 cells were initially selected because previously published results (10) indicated that their levels of p53 rise following genotoxin treatment. We verified this, and found in addition that p53 in these cells can be immunoprecipitated by a monoclonal antibody specific for wild-type p53. We also found that the level of p53 in these cells rises significantly following treatment with indirect genotoxins such as aflatoxin BI and 2-acetylaminofluorene, indicating that they possess significant amounts of the metabolic activities necessary for biotransformation (9.To determine the ability of this assay to predict carcinogenicity in rodents and to compare its performance with other proposed alternatives, we subjected 25

In vitro embryotoxicity testing of metals for dental use by differentiation of embryonic stem cell test

“…We subsequently found that silver and cobalt ions severely affect the IC 50 of both cells. Regarding cobalt, Duerksen-Hughes et al (1999) evaluated cobalt sulfate based on the ability of cells to increase the level of the tumor suppressor protein p53 that is activated in response to DNA damage, and found that it had a medium genotoxicity. Also, Lison et al (2001) reported that the cobalt (III) positive ion exhibited genotoxicity and carcinogenesis, but added that the data collected was insufficient to prove this.…”

Scientific Opinion on Flavouring Group Evaluation 95 (FGE.95): Consideration of aliphatic, linear or branched-chain saturated and unsaturated alcohols, aldehydes, acids and related esters evaluated by JECFA (69th meeting) structurally related to esters of

“…In a recently developed assay for DNA damage measuring induction of p53 tumour suppressor protein in mouse fibroblasts (NTCT 929 cell line) in vitro, citral gave positive results at concentrations of 10-EFSA Journal 2010; 8(11): 1207 30 µg/ml after 17 h of incubation. In this assay, increased expression of p53 is considered to indicate the induction of DNA damage (Duerksen-Hughes et al, 1999).…”

Flavouring Group Evaluation 72 (FGE.72): Consideration of aliphatic, branched-chain saturated and unsaturated alcohols, aldehydes, acids, and related esters evaluated by the JECFA (61st meeting) structurally related to branched- and straight-chain unsatur

“…In a recently developed assay for DNA damage measuring induction of p53 tumour suppressor protein in mouse fibroblasts (NTCT 929 cell line) in vitro, citral gave positive results at concentrations of 10-30 µg/ml after 17 h of incubation. In this assay, increased expression of p53 is considered to indicate the induction of DNA damage (Duerksen-Hughes et al,1999).…”

“…Citral was not mutagenic in several valid Ames tests (Gomes-Carneiro et al, 1998;Ishidate et al, 1984;NTP, 2003e;Zeiger et al, 1987), and it did not induce chromosome aberrations in a valid in vitro study with chinese hamster ovary (CHO) cells (NTP, 2003e (Yoo, 1986) and the induction of the tumour suppressor protein p53 (Duerksen-Hughes et al, 1999) are considered of limited relevance for the overall evaluation. The Panel concluded that for citral genotoxicity is not of concern.…”