Characterization of human breast cancer cell lines for the studies on p53 in chemical carcinogenesis

To know whether the molecular responses to chemical carcinogens reflect only cell line specific molecular responses, or whether they can be regarded as characteristic of breast tissue, we have characterized four human breast cancer cell lines (MDA-MB-231, MDA-MB-468, T47-D, ZR-75-1). The activation of benzo(a)pyrene (BP), a model compound of polycyclic aromatic hydrocarbons, to its genotoxic BP-diolepoxide (BPDE) and p53 response and cell viability after BP exposure, and the p53 status in these cell lines were analyzed. Both TP53 (exons 5–8) mutations and total and phospho-p53 were analyzed. Three of the four cell lines clearly activated BP to BPDE-DNA adducts (MDA-MB-468, T47-D, ZR-75-1) and three had a mutation in the TP53 gene (MDA-MB-231, MDA-MB-468, T47-D). After BP-treatment the strongest p53 protein induction and phosphorylation at serine 392 was found in ZR-75-1 cells with a wt TP53 gene. Viability decreased dramatically only in ZR-75-1 and MDA-MB-468 cells although the relative cell number was reduced in all the cell lines suggesting that BP affects cell proliferation. In conclusion, a TP53 mutation does not necessarily lead to a loss of p53 protein response. This study stresses the importance of characterization of all human cancer cell lines for the intended targets of study.

► To use cancer cell lines in toxicological studies, they have to be characterized. ► Studied cells metabolize BP to BPDE. Differences in metabolic activity between cell lines exist. ► Mutation of TP53 gene was found in two cell lines in exon 8 and in one cell line in exon 6. ► Distinct differences in BP-induced responses were found in breast cancer cell lines. ► A mutation in TP53 does not prevent all responses of p53 protein.