Different bisphenols induce non-monotonous changes in miRNA expression and LINE-1 methylation in two cell lines

Abstract

4,4ʹ-Isopropylidenediphenol (bisphenol A, BPA), a chemical substance that is widely used mainly as a monomer in the production of polycarbonates, in epoxy resins, and in thermal papers, is suspected to cause epigenetic modifications with potentially toxic consequences. Due to its negative health effects, BPA is banned in several products and is replaced by other bisphenols such as bisphenol S and bisphenol F. The present study examined the effects of BPA, bisphenol S, bisphenol F, p,pʹ-oxybisphenol, and the BPA metabolite BPA β-d-glucuronide on the expression of a set of microRNAs (miRNAs) as well as long interspersed nuclear element-1 methylation in human lung fibroblast and Caco-2 cells. The results demonstrated a significant modulation of the expression of different miRNAs in both cell lines including miR-24, miR-155, miR-21, and miR-146a, known for their regulatory functions of cell cycle, metabolism, and inflammation. At concentrations between 0.001 and 10 µg/ml, especially the data of miR-155 and miR-24 displayed non-monotonous and often significant dose–response curves that were U- or bell-shaped for different substances. Additionally, BPA β-d-glucuronide also exerted significant changes in the miRNA expression. miRNA prediction analysis indicated effects on multiple molecular pathways with relevance for toxicity. Besides, long interspersed nuclear element-1 methylation, a marker for the global DNA methylation status, was significantly modulated by two concentrations of BPA and p,pʹ-oxybisphenol. This pilot study suggests that various bisphenols, including BPA β-d-glucuronide, affect epigenetic mechanisms, especially miRNAs. These results should stimulate extended toxicological studies of multiple bisphenols and a potential use of miRNAs as markers.

BPA Decreases PDCD4 in Bovine Granulosa Cells Independently of miR-21 Inhibition

“…miR-21 inhibition significantly increases PDCD4 protein, but not PTEN. The increased PDCD4 protein not only validates a functional knockdown in this study, but also supports the antiapoptotic function of miR-21 [ 30 ]. PDCD4 is a proapoptotic factor that possesses a 3′UTR seed sequence that is strongly complementary to miR-21 [ 12 ].…”

“…Although this does not directly explain our results, it does suggest a potential mechanism by which PTEN expression is protected from the actions of BPA; PTEN may not be a direct target of both BPA and miR-21 in bovine granulosa cells. It is important to note that miR-21 is not only involved in apoptosis, but has been functionally linked to the establishment of differentiation or pluripotency in bovine embryos [ 84 ], production of aromatase and estradiol in granulosa cells [ 85 ], and inhibition of tumor suppressor genes [ 10 , 30 ]. The disruptions in miR-21 expression via BPA can influence each of these processes in a unique manner that will ultimately contribute to poor fertility and increased risk of reproductive disorders.…”

“…BPA has been shown to affect epigenetics, such as DNA methylation and histone modification, in part, by disrupting the activity of methyltransferase and acetylase enzymes [ 8 , 28 , 29 ]. BPA alters miRNA expression profiles [ 30 , 31 , 32 , 33 , 34 ] with multiple reports of BPA-dependent increases in miR-21 expression in bovine oocytes and granulosa cells [ 27 ], in breast cancer cells [ 35 ], in human ovarian cancer cells [ 36 ], in human placental cells [ 37 , 38 ], and in mice pancreatic cells [ 39 ]. In a previous study from our group, BPA not only increased the expression of mature miR-21 but also pri-miR-21 in bovine COCs [ 27 ].…”

Application of the Key Characteristics of Carcinogens to Bisphenol A

“…168 Global methylation was altered in several human cell types in vitro, including neuroblastoma cell lines, mesenchymal bone marrow stem cells, embryonic kidney cells, hepatoma cells, embryonic stem cells, breast epithelial cells, prostate cancer cells, colorectal carcinoma cells, and umbilical vein endothelial cells. 137,154,165,[168][169][170][171][172][173] Some studies did not observe an effect of BPA on global methylation. 162,174,175 Other epigenetic effects observed in human cells in vitro included altered expression of microRNAs, overexpression of DNA methyltransferases (which regulate DNA methylation machinery; overexpression can lead to reduced expression of tumor suppressor genes), 176 and histone modifications.…”

Potential Pathogenic Impact of Cow’s Milk Consumption and Bovine Milk-Derived Exosomal MicroRNAs in Diffuse Large B-Cell Lymphoma

“…Importantly, plasticizers like BPA modify the expression of oncogenic microRNAs (miRs) [ 196 , 197 ]. Notably, BPA exposure increased the expression of miR-21-5p in the majority of cell lines studied [ 196 , 197 , 198 , 199 , 200 ].…”