Abstract
Tricresyl phosphate (TCP) is one of the organophosphorus flame retardants (OPFRs) used as plasticizer in consumer products and mixed as a lubricant in commercial jet engine oil, reportedly induce neurotoxicity and aerodynamic syndrome. No studies have been attempted so far on TCP to induce hepatotoxicity in human cells. This study for the first time confirms the hepatotoxic potential and activation of cancer pathways in TCP treated human hepatocellular cells (HepG2). MTT and NRU data showed 39.3% and 49.85% decline in HepG2 survival when exposed to the highest concentration of TCP (400 mu M) for 3 days. Comet assay showed 27.1-fold greater DNA damage in cells treated with TCP (400 mu M). Flow cytometric analysis revealed an upsurge in the intracellular reactive oxygen species (ROS) and nitric oxide (NO) production in cells, affirming oxidative stress. TCP (400 mu M) exposure resulted in 27% reduction in Rh123 fluorescence, indicating dysfunction of mitochondrial membrane potential (Delta psi m). Cell cycle analysis exhibited 62.53% cells in the subGl apoptotic phase after TCP (400 mu M) treatment, also a massive increase in Ca2+ influx validate the on-set of apoptosis in cells. Immunofluorescence of TCP exposed cells showed activation of p53, caspase3, caspase9 reaffirming the involvement of mitochondrial-dependent intrinsic apoptotic signaling. qPCR array of 84 genes unravel the transcriptomic alterations in HepG2 cells after TCP treatment. mRNA transcripts of ATP5A1, GADD45A, IGFBP5, SODI, STM1s11 genes were prominently upregulated providing candid evidence on TCP mediated activation of human cancer pathways to orchestrate the apoptotic death of HepG2 cells, specifying hepatotoxic potential of TCP. (C) 2019 Elsevier Ltd. All rights reserved.