The cytotoxicity of organophosphate flame retardants on HepG2, A549 and Caco-2 cells

In order to elucidate the cytotoxicity of organophosphate flame retardants (OPFRs), three human in vitro models, namely the HepG2 hepatoma cells, the A549 lung cancer cells and the Caco-2 colon cancer cells, were chosen to investigate the toxicity of triphenyl phosphate (TPP), tributylphosphate (TBP), tris(2-butoxyexthyl) phosphate (TBEP) and tris (2-chloroisopropyl) phosphate (TCPP). Cytotoxicity was assayed in terms of cell viability, DNA damage status, reactive oxygen species (ROS) level and lactate dehydrogenase (LDH) leakage. The results showed that all these four OPFRs could inhibit cell viability, overproduce ROS level, induce DNA lesions and increase the LDH leakage. In addition, the toxic effects of OPFRs in Caco-2 cells were relatively severer than those in HepG2 and A549 cells, which might result from some possible mechanisms apart from oxidative stress pathway. In conclusion, TBP, TPP, TBEP and TCPP could induce cell toxicity in various cell lines at relatively high concentrations as evidenced by suppression of cell viability, overproduction of ROS, induction of DNA lesions and increase of LDH leakage. Different cell types seemed to have different sensitivities and responses to OPFRs exposure, as well as the underlying potential molecular mechanisms.