Involvement of NLRP3/Caspase-1/GSDMD-Dependent Pyroptosis In BPA-Induced Apoptosis of Neuroblastoma Cells

Abstract

BackgroundBisphenol A (BPA) is an additive in polycarbonate and epoxy resin particles with endocrine disrupting effects. Previously it has been reported that BPA is neurotoxic via induction of cell apoptosis and inflammation, and our recent studies showed that even at nanomolar concentrations BPA accelerated the apoptosis and death of human neuroblastoma cells from both genders, whose mechanisms remain, however, unidentified.ResultsHuman neuroblastoma cell lines developed from male and female subjects, IMR-32 and SK-N-SH, respectively, were exposed to BPA at concentrations ranging from 1 nM to 100 μM, for 24 h, with or without epigallocatechin gallate (EGCG, 4 or 8 μM), Z-YVAD-FMK (1 or 10 μM, caspase-1 inhibitor), and ICI182.780 (100 nM or 3 μM, estrogen receptor inhibitor) as modulators. The results showed that BPA nonlinearly upregulated the levels of IL-18, ASC, GSDMD and NLRP3 mRNAs and that of NLRP3, caspase-1, GSDMD and IL-1β proteins in IMR-32 and SK-N-SH cells. Noticeably, the mRNA levels of caspase-1 and IL-1β were changed differently in the two cell lines: the level of caspase-1 mRNA was enhanced in IMR-32 cells but suppressed in SK-N-SH cells, and that of IL-1β was suppressed in IMR-32 cells but enhanced in SK-N-SH cells. The level of GSDMD expression in situ was along with the increase in the release of IL-1β, IL-18, caspase-1 and lactate dehydrogenase (LDH). Additionally, Z-YVAD-FMK, ICI182.780 and EGCG significantly reversed the changes of the above mRNAs/proteins induced by BPA. BPA significantly reduced the level of the reactive oxygen species and the rate of LDH leakage and apoptosis, while obviously increased the cell viability and the mitochondrial membrane potential. Meanwhile, Z-YVAD-FMK and ICI182.780 abruptly reduced the levels of Bak1, Bax, Bcl-2 and caspase-3 proteins induced by BPA. ConclusionAs mediated by the estrogen receptor, BPA may induce the pyroptosis of neuroblastoma cells through NLRP3/caspase-1/GSDMD signaling pathway, and caspase-1-dependent pyroptosis may be involved in BPA-induced apoptosis, which is alleviated by EGCG, an anti-oxidation agent.