Panax notoginseng saponins induce apoptosis in retinoblastoma Y79 cells via the PI3K/AKT signalling pathway

Abstract

This study aimed to investigate the effects of Panax notoginseng saponins (PNS) on the proliferation, apoptosis, and PI3K/AKT signalling pathways of retinoblastoma Y79 cells to explore the possible mechanism of action of PNS on retinoblastoma. The effects of PNS and carboplatin on the proliferation of Y79 cells were examined using cell counting kit-8 assay. And the apoptosis rate, the mRNA and protein levels of apoptosis-related genes and the expression of PI3K/AKT pathway protein were assessed. PNS effectively inhibited the proliferation (P < 0.05) and increased apoptosis of Y79 cells (P < 0.05). Compared with the negative control, the Y79 cells treated with PNS had significantly increased (P < 0.05) mRNA and protein expression of Bax, caspase-3, caspase-8, and caspase-9 and elevated levels of cleaved caspase-3, cleaved caspase-8, and cleaved caspase-9 proteins (P < 0.05). The mRNA and protein expression of the apoptosis suppressor gene Bcl-2 was inhibited (P < 0.05), while the Bax/Bcl-2 values of the cells in the drug group were significantly higher than those in the negative group (P < 0.01). After treatment with PNS, the total protein expression of PI3K and AKT1 in the Y79 cells did not show significant differences compared with the negative group (P > 0.05), although the expression of phosphorylated proteins p-PI3K, p-AKT (Thr308), p-AKT (Ser473), and p-mTOR were significantly reduced (P < 0.05). Meanwhile, the antagonist protein of the pathway phosphatase and tensin homologue deleted on chromosome 10 (PTEN) expression was increased (P < 0.01). Cellular alterations following inhibition of the PI3K/AKT pathway using LY294002 were similar to those of PNS, the proliferation of Y79 cells was also inhibited, and cell apoptosis increased (P < 0.001). The expression of Bax, caspase-3, caspase-8, caspase-9, and activation proteins cleaved caspase-3, cleaved caspase-8, and cleaved caspase-9 was also significantly higher than that in the negative control (P < 0.05). Bcl-2 protein expression was decreased (P < 0.01), and the Bax/Bcl-2 ratio was higher than that in the negative control (P < 0.001). Overall, we demonstrated that PNS effectively inhibited the proliferation and promoted the apoptosis of retinoblastoma Y79 cells. The apoptosis-promoting effect of PNS may involve the inhibition of the PI3K/AKT signalling pathway, which subsequently regulates the expression of apoptosis-related genes.