Growth-promoting effects of low-level butyl benzyl phthalate exposure on human neuroblastoma SH-SY5Y cells

The purpose of present study was to investigate the impact of butyl benzyl phthalate (BBP) on SH-SY5Y neuroblastoma cells in vitro. The cell counting kit-8 was used to measure cell proliferation and flow cytometry was utilized to study cell cycle phases and apoptosis. Western blotting and quantitative real-time polymerase chain reaction were used to detect levels of aromatase, estrogen receptors (ERs) and some apoptosis and cell cycle-related genes. Results showed BBP-stimulated SH-SY5Y cells in a dose-dependent manner and produced a reverted U-shaped dose-response curve. BBP at lower concentrations (0.01 and 0.1 mu m) significantly induced cell proliferation while inhibited cell growth at 300 mu m. The promoting effect of estradiol could be entirely blocked by administration of ICI182 780, a pure antagonist of ERs, while the effect of BBP could be partly blocked. Additionally, we confirmed 0.1 mu m BBP-induced cell proliferation caused the arrest of cells in S phase and inhibited apoptosis, which might be partially explained by the decreased expression of p53, the increased expression of proliferating cell nuclear antigen, Bcl-2 and cell cycle regulator cyclin-D1, and the activation of aromatase. The addition of ICI182 780 had no effect on BBP-induced ER beta mRNA expression, whereas ICI182 780 could effectively counteract the effect of estradiol. Moreover, pretreatment with ICI182 780 could block the induction of aromatase protein expression and activity by BBP, showing an involvement of ERs. Except for the ER pathway, these results showed there might be other pathways involved in promoting the effects of low-level BBP on SH-SY5Y cells, which require further investigation.