Tris(2-chloroethyl) Phosphate (TCEP) Elicits Hepatotoxicity by Activating Human Cancer Pathway Genes in HepG2 Cells

Abstract

Tris(2-chloroethyl) phosphate (TCEP) is one of the organophosphorus flame retardants (OPFRs) used in consumer commodities and have been detected in human body fluids. Research on TCEP-induced transcriptomic alterations and toxicological consequences in liver cells is still lacking. Herein, human hepatocellular (HepG2) cells were treated with 100, 200, and 400 μM TCEP for 3 days to quantify hepatotoxicity by MTT, NRU, and comet assays. Apoptosis, mitochondrial membrane potential (ΔΨm), oxidative stress, and Ca2+ influx were measured by flow cytometry. A qPCR array was employed for transcriptomic analysis. MTT and NRU data showed 70.92% and 75.57% reduction in cell survival at 400 μM. In addition, 20-fold greater DNA damage was recorded at 400 μM. Cell cycle data showed 65.96% subG1 apoptotic peak in 400 μM treated cells. An elevated level of oxidative stress, esterase, Ca2+ influx, and ΔΨm dysfunction were recorded in TCEP-treated cells. Out of 84 genes, the qPCR array showed upregulation of 17 genes and downregulation of 10 key genes belonging to human cancer pathways. Our study endorses the fact that TCEP possesses hepatotoxic potential at higher concentrations and prolonged exposure. Hence, TCEP may act as a cancer-inducing entity by provoking the gene network of human cancer pathways.

Cyto-Genotoxic and Transcriptomic Alterations in Human Liver Cells by Tris (2-Ethylhexyl) Phosphate (TEHP): A Putative Hepatocarcinogen

“…However, the transient G2/M arrest was not a permanent and the cells arrested in the SubG1 apoptotic phase (100, 200, 400 μM), clearly indicating a solid reason to recognize the unsuccessful repair of DNA [ 49 ]. Similar to our data, TCP-, TECP-, and TDCPP-exposed cell lines have shown DNA damage [ 29 , 47 , 50 ]. We further quantified the cell cycle phases and verified the activation of apoptotic proteins.…”

“…P53, being a DNA damage response protein, translocates to the nucleus and is known to activate proapoptotic and cell cycle checkpoint genes [ 51 , 52 ], while the initiator caspase 9 becomes activated upon mitochondrial injury and cleaves caspase 3 to effectuate the apoptotic process in cells [ 53 ]. Similar to our finding, TCP-, TCEP-, and TDCPP-treated HepG2, RAW264.7 macrophages, and HCECs cells also resulted in the activation of P53, caspase 9 and 3 proteins to effectuate the apoptotic process [ 29 , 47 , 50 ].…”

“…Consequently, our flow cytometric data affirm the onset of oxidative stress, which affected the mitochondrial functionality of HepG2. In addition to that, TEHP treatment elevated intracellular esterase activity, which has been reported to occur due to obtrusion of cell division [ 46 ]; a similar effect has been verified in earlier studies on OPFRs-exposed cells [ 29 , 47 ].…”

Organophosphorus Flame Retardant TDCPP Displays Genotoxic and Carcinogenic Risks in Human Liver Cells

“…Flow cytometry gave the freedom to analyze the activity of cells (fluorochromes stained) passing in a row from the laser beam, whose scattering patterns are captured by the optics and processed by electronics to generate data. We have analyzed the cell death and oxidative stress in TDCPP-exposed cells by flow cytometry as stated earlier [ 55 ]. After the exposure to TDCPP (100–400 μM, 3 days), cells were detached and pelleted at 3000 rpm for 3 min.…”

Insights into the Atmospheric Persistence, Transformation, and Health Implications of Organophosphate Esters in Urban Ambient Air

“…15−20 In particular, OPEs are extensively present in the urban ambient air of different parts of the globe, such as in Guangzhou, China (mean = 1.38 × 10 5 pg m −3 ), 21 Izmir, Turkey (mean = 4.43 × 10 3 pg m −3 ), 22 Stockholm, Sweden (median = 3.10 × m −3 ), 20 and Toronto, Canada (mean = 1.79 × 10 3 pg m −3 ). 19 Given the adverse health effects of OPEs, such as neurotoxicity, hepatotoxicity, and immunotoxicity, 23,24 their prevalence and persistence in urban ambient air certainly deserve broad attention. Additionally, transformation of OPEs via physicochemical and microbial processes can probably produce new atmospheric pollutants, which can be more toxic and more persistent than the parent OPEs.…”