Antiproliferative properties of Saussurea lappa Clarke root extract in SH-SY5Y neuroblastoma cells via intrinsic apoptotic pathway

Abstract

The dried roots of Saussurea lappa are used in traditional medicine for the treatment of dysentery, nausea, and vomiting, as well as for their antiulcer, anti-inflammatory, and antitumor properties. In this study, the cytotoxic activities of the ethanol extract of Saussurea lappa root extract (SLRE) on neuroblastoma cells were investigated, wherein the effect of the plant extracts on cancer cells has not been fully clarified. Here, cytotoxicity was examined by cell viability assay, fragmented DNA by DAPI, caspase-3 activity by immunofluorescence staining, and activation of proteins was detected by western blotting. SLRE was demonstrated to reduce human SH-SY5Y and rat B103 neuroblastoma cell viability more effectively than mouse and rat fibroblast cells. However, the SLRE-treated cells exhibited morphological changes including cell rounding, cell shrinkage, neurite retraction, and membrane blebbing, which indicated the initiation of apoptosis in the SH-SY5Y cells. Importantly, SLRE-induced cells displayed upregulation of the pro-apoptotic protein Bax and downregulation of the anti-apoptotic proteins Bcl-2, Bcl-xl, and Mcl-1, which suggest the mitochondia-mediated apoptotic pathway. In addition, SLRE activated cleaved caspases-9 and -3, also indicating the intrinsic caspase-mediated apoptosis pathway. Consequently, phosphatidylinositide-3-kinase/protein kinase B (AKT) and glycogen synthase kinase-3β (GSK-3) protein expression and activity were downregulated by SLRE treatment, suggesting that the growth inhibitory activity of this plant extracts is associated with these pathways. Therefore, the findings from this study demonstrated that the growth inhibitory and cytotoxic effects of SLRE on SH-SY5Y cells are accomplished through the mitochondria-mediated pathway, and that this natural extract might be useful as an anticancer agent for neuroblastoma treatment.