The Role of Endocrine and Dioxin-Like Activity of Extracts of Petroleum Substances in Developmental Toxicity as Detected in a Panel of CALUX Reporter Gene Assays

Abstract

Recent evidence suggests that the interaction of polycyclic aromatic hydrocarbons (PAHs), present in some petroleum substances (PS), with particular nuclear-hormone-receptors and/or the dioxin (aryl hydrocarbon receptor [AhR]) receptor, may play a role in the prenatal developmental toxicity (PDT) induced by these substances. To address this hypothesis, we evaluated the possible endocrine and dioxin-like activity of the dimethylsulfoxide (DMSO)-extracts of 9 PS, varying in PAH content, and 2 gas-to-liquid (GTL) products, containing no PAHs but having similar other properties as PS, using a series of Chemical Activated LUciferase gene eXpression (CALUX) assays. The results show that the extracts of PS tested in this study possess various endocrine and dioxin-like activities and these in vitro potencies are associated with the quantity and type of PAHs they contain. All tested DMSO-extracts of PS show a strong AhR agonist activity and rather weak antiprogesterone, antiandrogen, and estrogenic activities. In the assays that evaluate thyroid-related and antiestrogen activity, only minor effects of specific extracts, particularly those with a substantial amount of 4–5 ring PAHs, ie, sample No. 34, 98, and 99, were observed. None of the GTL extracts interacted with the selected receptors. Of all assays, the AhR agonist activity correlates best (R2 = 0.80) with the in vitro PDT of the substances as quantified previously in the embryonic stem cell test, suggesting an important role of the AhR in mediating this effect. Hierarchic clustering of the combined CALUX data clustered the compounds in line with their chemical characteristics, suggesting a PS class-specific effects signature in the various CALUX assays, depending on the PAH profile. To conclude, our findings indicate a high potential for endocrine and dioxin-like activity of some PS extracts which correlates with their in vitro PDT and is driven by the PAHs present in these substances.

Prenatal developmental toxicity testing of petroleum substances using the zebrafish embryotoxicity test_suppl

“…Moreover, a pronounced aryl hydrocarbon (AhR)-mediated activity was found upon exposure to increasing concentrations of DM-SO-extracts of the same PS, as tested in the AhR CALUX assay. This AhR-mediated activity correlated well with the in vitro PDT potency in the EST, suggesting an important role of the AhR in mediating this effect (Kamelia et al, 2018). These earlier results corroborated the notion that PAHs are the primary inducers of PDT in some PS and that the AhR may play an important role in the underlying mode of action.…”

“…This hypothesis is supported by our recent findings, where the EST and a panel of CALUX reporter gene assays were used to evaluate the PDT potency and possible underlying mechanism of PDT of the DMSO-extracts of PS and GTL products (Kamelia et al, 2017(Kamelia et al, , 2018. In the EST, DMSO-extracts of 9 PS, varying in PAH level and content, were able to inhibit the differentiation of ES-D3 cells into beating cardiomyocytes, where GTL products that contain no PAHs showed no effects (Kamelia et al, 2017).…”

“…4B). Further, a good correlation also exists between the in vitro potencies in the EST and the AhR CALUX assay, showing an R 2 value of 0.80 (Kamelia et al, 2018; data and graph are provided in Appendix E 1 ).…”

“…Data for the AhR-mediated activity of the DMSO-extracts of 9 PS and 2 GTL products, as tested in the AhR CALUX assay, were taken from our recently published study (Kamelia et al, 2018). Briefly, H4IIE.luc cells were exposed to increasing concentrations of the DMSO-extracts of the aforementioned substances for 6 h. The luciferase induction activity upon exposure was then measured, and the amount of produced luminescence was used to quantify the AhR-mediated activity induced by the respective test compound.…”

Mineral oil in food, cosmetic products, and in products regulated by other legislations

“…First results were published on the Concawe website in September 2018 (https://www.concawe. eu/publication/cat-app-project-2018-results-brochure, last accessed 2019-06-20) and in the peer-reviewed literature (Kamelia et al 2017;Kamelia et al 2018;Kamelia et al 2019a;Kamelia et al 2019b). The project is interesting from a scientific perspective while the regulatory acceptability of its results will need further discussion.…”