Minor structural modifications of bisphenol A strongly affect physiological responses of HepG2 cells

Abstract

Bisphenols represent a large group of structurally similar compounds. In contrast to bisphenol A (BPA) and bisphenol S (BPS), however, toxicological data are usually scarce, thus making bisphenols an ideal candidate for read-across assessments. BPA, bisphenol C (BPC) and a newly synthesized bisphenol A/C (BPA/C) differ only by one methyl group attached to the phenolic ring. Their EC 50 values for cytotoxicity and logP OW values are comparable. However, the estrogenic activities of these bisphenols are not comparable and among this group only BPC leads to a decrease of the mitochondrial membrane potential and ATP concentration in HepG2 cells. Conversely, the cell division rate was decreased by BPS, BPA, BPC and BPA/C at 10% toxicity (EC 10 ). At lower concentrations, only BPC significantly affected proliferation. The pro-inflammatory cytokines TGFB1 and TNF were significantly upregulated by BPC only, while SPP1 was upregulated by BPA, BPA/C and BPS. BPC led to the release of cytochrome c from mitochondria, indicating that this compound is capable of inducing apoptosis. In conclusion, the read-across approach revealed non-applicable in the case of the various structurally and physicochemically comparable bisphenols tested in this study, as the presence of one or two additional methyl group(s) attached at the phenol ring profoundly affected cellular physiology. Keywords 2,2-bis(4-hydroxyphenyl) propane • 2,2-bis(4-hydroxy-3-methylphenyl) propane • 4,4′-Sulfonyl-diphenol • Mitochondria • Intrinsic apoptosis • HepG2 cells Abbreviations BPA Bisphenol A BPC Bisphenol C BPS Bisphenol S BPA/C Bisphenol A/C EC 50 Half maximal effective concentration EC 10 10% of the effective concentration ΔΨ m Mitochondrial membrane potential CyC Cytochrome c BCL2 B cell lymphoma 2 SPP1 Osteopontin TNF Tumor necrosis factor α TGFB1 Transforming growth factor β Electronic supplementary material The online version of this article (

Bisphenol A Diglycidyl Ether (BADGE) and Bisphenol Analogs, but Not Bisphenol A (BPA), Activate the CatSper Ca2+ Channel in Human Sperm

“…It seems that the bisphenols with larger/bulkier side chains are more efficacious and that relatively small molecular differences between the bisphenols can alter their effects significantly ( Table 1). This is in line with a previous study showing that the read-across approach was non-applicable for otherwise structurally comparable bisphenols (45). Interestingly, low doses of BPAF, BPB, BPF, BPS, and BPA have all been shown to induce Ca 2+ signals in SKBR3 cells via the G protein-coupled estrogen receptor (GPER) (46), with BPAF and BPB being more efficacious than BPF, BPS, and BPA.…”

In Vitro Screening of 21 Bisphenol A Replacement Alternatives: Compared with Bisphenol A, the Majority of Alternatives Are More Cytotoxic and Dysregulate More Genes in Avian Hepatocytes

“…Therefore, we evaluated the potential relationship between the log octanol–water partition coefficient (logP) and logLC50 values for all compounds that elicited an effect on cell viability (18 alternatives + BPA) and determined that there was an inverse linear relationship (Figure 1; r 2 = 0.745; p = 0.49 –07 ). Thus, cytotoxicity increased with decreasing water solubility (i.e., higher logP), which was comparable with a finding reported by Padberg et al (2019). Compounds with logP > 5 would be expected to permeate the lipid‐rich plasma membrane more easily (Yang and Hinner 2015) to exert effects.…”

Gene X environment: the cellular environment governs the transcriptional response to environmental chemicals

“…Including RNA from cells that have entered the cell death pathway can confound results when evaluating intracellular signaling. For example, human serum BPA levels are estimated at 0.002-0.004 μM, but in some reported datasets, BPA was tested in HepG2 cells up to 200 mM [41,42]. The half maximal concentration of BPA when evaluating 24 h cytotoxicity in HepG2 cells was demonstrated to be 261 μM, suggesting that gene expression studies performed with HepG2 cells treated for 48 h with millimolar concentrations may reflect the induction of cell death rather than endocrine disrupting activities [42].…”

“…For example, human serum BPA levels are estimated at 0.002-0.004 μM, but in some reported datasets, BPA was tested in HepG2 cells up to 200 mM [41,42]. The half maximal concentration of BPA when evaluating 24 h cytotoxicity in HepG2 cells was demonstrated to be 261 μM, suggesting that gene expression studies performed with HepG2 cells treated for 48 h with millimolar concentrations may reflect the induction of cell death rather than endocrine disrupting activities [42]. Another important consideration when determining the physiological effect of EDCs is the in vivo metabolism of environmental chemicals into conjugated forms, which can alter their bioactivity [43].…”