Acute exposure to DEHP metabolite, MEHP cause genotoxicity, mutagenesis and carcinogenicity in mammalian Chinese hamster ovary cells

Abstract

Di-(2-ethylhexyl) phthalate (DEHP), the common plasticizer used in the production of polyvinyl chloride, can be converted to the more potent metabolite mono-ethylhexyl phthalate (MEHP). Epidemiological studies have shown an association with elevated induction of rat hepatic cancer and reproductive toxicity in response to MEHP exposure. However, the mechanism of genotoxicity and carcinogenicity induced by MEHP treatment remains unclear. As a means to elucidate the mechanisms of action, lethality and mutagenicity in the adenine phosphoribosyltransferase (aprt+/-) gene induced in several CHO cell types by MEHP were assessed. Dose-response relationships were determined in the parental AA8 cell line, its nucleotide repair-deficient UV5 and base repair-deficient EM9 subclones, and also in AS52 cells harboring the bacterial guanine-hypoxanthine phosphoribosyltransferase (gpt) gene and its derived AS52-XPD-knockdown and AS52-PARP-1-knockdown cells. Treatment of AS52 with MEHP led to intracellular production of reactive oxygen species (ROS) and DNA strand breaks in a dose-dependent manner. Separately, mutations in the gpt gene of AS52 cells were characterized and found to be dominated by G:C to A:T and A:T to G:C transitions. Independent AS52-mutant cell (ASMC) clones were collected for the sequential in vivo xenograft tumorigenic studies, 4 of total 20 clones had aggressive tumor growth. Moreover, microarray analysis indicated miR-let-7a and miR-125b downregulated in ASMC, which might raise oncogenic MYC and RAS level and activate ErbB pathway. Comparative evaluation of the results indicates that the principal mechanism of this mutagenic action is probably to be through generation of ROS, causing base excision damage resulting in carcinogenicity.

Oncogenic Role of miRNA by Environmental Exposure to Plasticizers: A Systematic Review.

“…In alphabetical order we have included the following studies: Buñay et al 2017 [27], Chang et al 2017 [43].…”

Ascorbic acid ameliorates dysregulated folliculogenesis induced by mono‐(2‐ethylhexyl)phthalate in neonatal mouse ovaries via reducing ovarian oxidative stress

“…Phthalates are synthetic plasticizers, and they are widely used in the industrial products of medical devices, children's toys and clothing (Chang, Tseng, Lin, Chuang, & Chao, 2017; Du et al., 2016). Di‐(2‐ethylhexyl)phthalate is one of the most common subtypes of phthalates.…”

Phthalates mixtures in bottled water in Iran: human health risk assessment using direct and indirect exposure assessment

“…Human biomonitoring studies support the notion that exposure to phthalates impairs semen quality and decreases sex hormone levels causing fertility problems in reproductive-age men (Bloom et al, 2015;Liu et al, 2012;Wang et al, 2016. Several studies found statistically significantly lower sperm concentration and sperm counts when exposure to phthalates increased (Pant et al, 2008(Pant et al, , 2014Kranvogl et al, 2014;Specht et al, 2014;Bloom et al, 2015;Chang et al, 2017). Some others observed that sperm motility was statistically significantly lower when DEHP exposure increased (Pant et al, 2008;Huang et al, 2011;Jurewicz et al, 2013;Kranvogl et al, 2014;Axelsson et al, 2015).…”

“…Recently, Chang et al (2017) reported that also MEHP induces intracellular ROS production leading to DNA damage, with the amount of ROS generated being dependent on the MEHP concentration. Mammalian Chinese hamster ovary (AS52) cells were used in the Comet assay to evaluate whether MEHP causes DNA single-strand breaks at concentrations of 0, 10, 25 and 50 mM.…”

“…MEHP indeed caused significant single-strand breaks in the cells. Therefore, Chang et al, concluded that MEHP induces oxidative stress and causes DNA damage (Chang et al, 2017). It is important to note that in a Comet assay cytotoxicity resulting in apoptosis may also be the cause of DNA damage, given that apoptosis induces DNA fragmentation.…”