The Primary Study Of The Anti-tumor Effect And Mechanism Of Litchi Seed Extract In Vitro

Objective:We observed the anti-tumor activity of Lichi seed extract in vitro,the apoptosis induced by Litchi seed extract L2.3 on human hepatocellular carcinoma cell line HepG-2 and human neuroblastoma cell line SH-SY5Y,and the change of the activity of caspase-3,caspase-8, caspase-9 and Fas in apoptosis process.We tried to explore its mechanism of inducing HepG-2 and SH-SY5Y cells' apoptosis.Methods:The inhibition of different Litchi seed extracts on tumor cell lines in vitro was determined by MTT assay.The most effective fraction,L2.3,was chosen to test the activities on anti-proliferative time-effective and apoptosis induction and cell cycle alteration through the Hoechst 33258 staining and flow cytometric assay.The activity of caspase-3,caspase-8 and caspase-9 was determined by a caspases colorimetric assay kit.FCM analysis was carried out to examine the Fas protein expression.Results:(1) Cell inhibition experiments in vitro:thirteen kinds of Litchi seed extracts had different inhibitory intensity on 6 tumor cell lines(including A375,A549,HEp-2,Hela,HepG-2 and SH-SY5Y cells),especially the L2.3,it had the strongest inhibitory effect on Hela,HepG-2 and SH-SY5Y cells and it was observed in a dose- and time- dependent manner(P＜0.05).L2.3 had inhibitory effect on Vero cells at high concentration.(2) The cell and nuclear morphological changes were observed under the inverted microscope and fluorescence microscope after treated by L2.3 for 48 h.The chromatin of the treated HepG-2 and SH-SY5Y cells pyknosised and there were some apoptotic body with thick white-blue fluorescent in Hoechst 33258 stained cells.At the concentrations of 100,50μg/mL,L2.3 caused decrease of the percentages of HepG-2 and SH-SY5Y cells in G₀/G₁ phase(P＜0.05),while increase those in S phase(P＜0.01).And the percentage of cells in G₂/M phase was also decreased.At the same time the apoptosis rate increased significantly(P＜0.05).The activity of caspase-3,caspase-8 and caspase-9 was increased with a time-dependent manner(P＜0.05).Fas protein expression of SH-SY5Y cells showed a significant increase after exposured to L2.3 for 48 h in a dose-dependent manner,but the Fas protein expression of HepG-2 cells merely increased at high concentrations.Conclusions.(1) Litchi seed extract L2.3 had different inhibitory intensity on several tumor cells and normal Africa green monkey kidney cells(Vero),of which the inhibitory effect on HepG-2 and SH-SY5Y cells were the strongest and were in a dose- and time- dependent manner. (2) Litchi seed extract L2.3 can inhibit the proliferation of HepG-2 and SH-SY5Y cells in vitro which may be concerned with inducing cell apoptosis and cell cycle arrest,and the studies demonstrated that the activation of caspase-3,caspase-8,caspase-9 and Fas protein expression increase may be involved in the pathway mediating the apoptosis of HepG-2 and SH-SY5Y cells induced with L2.3.