Intrinsic apoptotic pathway and G2/M cell cycle arrest involved in tubeimoside I-induced EC109 cell death

Objective： Squamous esophageal carcinoma is highly prevalent in developing countries, especially in China. Tu Bei Mu （TBM）, a traditional folk medicine, has been used to treat esophageal squamous cell carcinoma （ESCC） for a long term. tubeimoside I （TBMS1） is the main component of TBM, exhibiting great anticancer potential. In this study, we investigated the mechanism of TBMS1 cytotoxic effect on EC109 cells. Methods： Comparative nuclear proteomic approach was applied in the current study and we identified several altered protein spots. Further biochemical studies were carried out to detect the mitochondrial membrane potential, cell cycle and corresponding proteins＇ expression and location. Results： Subcellular proteomic study in the nucleus from EC109 cells revealed that altered proteins were associated with mitochondrial function and cell proliferation. Further biochemical studies showed that TBMSl-induced molecular events were related to mitochondria-induced intrinsic apoptosis and P21-cyclin B 1/cdc2 complex-related G2/M cell cycle arrest. Conclusions： Considering the conventional application of TBM in esophageal cancer, TBMS1 therefore may have a great potential as a chemotherapeutic drug candidate for ESCC.

Anti-proliferation and apoptosis-inducing effects of sodium aescinate on retinoblastoma Y79 cells

AIM:To investigate the anti-proliferation and apoptosisinducing effects of sodium aescinate(SA)on retinoblastoma Y79 cells and its mechanism.METHODS:Y79 cells were cultured at different drug concentrations for different periods of time(24,48,and 72 h).The inhibitory effect of SA on proliferation of Y79 cells was detected by the cell counting kit-8(CCK-8)assay,and the morphology of Y79 cells in each group was observed under an inverted microscope.An IC50 of 48 h was selected for subsequent experiments.After pretreatment with SA for 24 and 48 h,cellular DNA distribution and apoptosis were detected by flow cytometry.Real-time qunatitative polymerase chain reaction(RT-qPCR)and Western blot were used to assess changes in related genes(CDK1,CyclinB1,Bax,Bcl-2,caspase-9,caspase-8,and caspase-3).RESULTS:SA inhibited proliferation and induced apoptosis of Y79 cells in a time-dependent and concentrationdependent manner.Following its intervention in the cell cycle pathway,SA can inhibit the expression of CDK1 and Cyclin B1 at the mRNA and protein levels,and block cells in the G2/M phase.In caspase-related apoptotic pathways,up-regulation of Bax and down-regulation of Bcl-2 caused caspase-9 to self-cleave and further activate caspase-3.What’s more,the caspase-8-mediated extrinsic apoptosis pathway was activated,and the activated caspase-8 was released into the cytoplasm to activate caspase-3,which as a member of the downstream apoptotic effect group,initiates a caspase-cascade reaction that induces cell apoptosis.CONCLUSION:SA inhibits the proliferation of Y79 cells by arresting the cell cycle at the G2/M phase,and induces apoptosis via the caspase-related apoptosis pathway,indicating that SA may have promising potential as a chemotherapeutic drug.