Molekulartoxikologische Untersuchungen zu Mechanismen der Toxizität von 2-Alkylcyclobutanonen in humanen Kolonepithelzellen
The irradiation of fat-containing food like meat, eggs, crustaceans or several fruits results in the formation of 2-alkylcyclobutanones (2ACB), cyclic derivatives from common fatty acids. Because they do not occur in unirradiated food and hence they develop due to irradiation, 2ACB are classified as food contaminants, the toxicological relevance of which had been demonstrated already. High doses of 2ACB lead to DNA damage in studies with human colon cells and advanced the growth of colon tumours in rats. To elucidate the underlying mechanisms of genotoxicity this work investigated the molecular-toxicological characteristics of common 2ACB, namely 2-dodecyl- (2dDCB), 2-tetradecyl- 2(tDCB), 2-tetradecenylcyclobutanone (2tDeCB) and 4-tetradecyl--butyrolactone (4tDBL). The relative sensitivities of human colon cells, representing different stages of tumour development (HT29clone19A, LT97 adenoma cells) and healthy primary human colon epithelial cells were explored. Therefore the cells were exposed to 2dDCB, 2tDCB, 2tDeCB (150-2097 μM) and 4tDBL (150-1260 μM). To define acute cytotoxic effects (absolute cell numbers and viability) the trypan blue exclusion method was used after 30, 60, 90 and 120 minutes after treatment with cyclobutanones. Genotoxicity, reflected as strand breaks, was assessed using the alkaline version of the comet assay (30 minutes, 37°). Moreover also chromosomal changes and TP53 gene mutations were investigated by 24-color-FISH and 2-color-FISH respectively, in LT97 adenoma cells.