The Anti-tumor Effect Of Trichosanthin On Gastric Cancer Cell And Its Molecular Mechanism

Objective:The incidence and mortality of gastric cancer are high in china all the time.Trichosanthin(TCS)is isolated from the root of Chinese herb trichosanthes.Its potential anti-tumor activity has been attracting more and more attention in recent years.We attempt to find a new type of Chinese medicine for curing gastric cancer by inducing apoptosis,and ask whether TCS could be the potential drug or not.At the same time,we try to understand the relationship between structure and biological function of TCS by mutating the lysine(K)173/arginine(R)174 and lysine(K)177.Methods:Gastric cancer cells SGC7901 was cultured in dish to the logarithmic growth phase.The cell morphology and cell growth rates were observed after treatment of TCS at 0,7,14 and 28 pM.Flow cytometry was used to detect the cell cycle and apoptosis of gastric cancer cells SGC7901 after treatment of TCS.Western blotting was performed to check the expression of caspase-9,caspase-3,PARP,pERK,ERK in gastric cancer cells SGC7901.At the same time,we constructed mutants K173A/R174A and K177A by site directed mutagenesis.Finally,we checked their biological function by measuring luciferase activity in cell.Results:(1)Cell shrinkage,deformation and membrane blebs were observed in gastric cancer cells SGC7901 after treatment of TCS.Proliferation of gastric cancer cells SGC7901 was inhibited by TCS treatment after 34 hours.(2)Gastric cancer cells SGC7901 were arrested in S phase after treatment of TCS.(3)TCS treatment induced apoptosis(concentration dependent)of gastric cancer cells SGC7901.(4)The results of Western blotting showed that expression of caspase-9,Caspase-3,PARP was decreased in a dose-dependent manner after treatment of TCS.The expression of ERK was also decreased in a dose-dependent manner after treatment of TCS.ERK was activated after treatment of TCS(7 and 14μM)as more phosphorylated ERK detected.(5)Within the cell,luciferase activity was inhibited by co-transfection of pGL-3 and wild-type TCS.The inhibitory effect of mutant K173A/R174A on luciferase activity was stronger than that of wild-type TCS.Mutant K177A showed the strongest inhibitory effect on luciferase activity among three.Conclusions:Treatment of TCS could inhibit the growth of gastric cancer cells SGC7901 and induce apoptosis of gastric cancer cells SGC7901.Treatment of TCS could also activate ERK signaling pathway,which suggests that the apoptosis may be modulated by the ERK signaling pathway in this event.The wild-type TCS and mutatants are active in inhibiting ribosomal protein synthesis in the cell.The inhibition capacity of mutant K177A is stronger than that of mutant K173A/R174A.And inhibition capacity of mutant K173A/R174A is stronger than that of wild-type TCS.