The Effects And Mechanism Of TPs And EGCG On Induced Cell Apoptosis

Tea (Camellia sinensis) is one of the most common beverages consumed worldwide. TPs (tea pplyphonels) are most abundant in green tea and they are mostly in the form of flavanols commonly known as catechins which include (-)-epicatechm(EC),(-)-epicatecbJn-3-gallate(ECG),(-)-epigallocatechin(ECG),(-)-epigallocatechin-3-gallate (EGCG). TPs demonstrated profound biochemical and pharmacological including antioxidant activities, modulation of carcinogen matabolism and inhibition of cell proliferation. Recently, many experiments proved that TPs could induce apoptosis in various cancer cells, hi the precent study, the action of TPs and EGCG inhibited various human caner cells in vitro were investigated using human lung cancer D6 cells, human stomach cancer SGC-7901cells, human liver cancer cells SMMC-7721 cells and human prostate cancer PC-3 cells as a model.In MTT assay, IPs and EGCG can inhibit the growth of four kinds of cancer cells in lower concentration (TPs and EGCG is 0-500 U g/mL and 0-625 u g/mL, respectively) in concentration- and time-dependent. Different effects of inhibition on cells were depent on the kind of cell. ICso values of TPs and EGCG against D6, SGC-7901, SMMC-7721, PC-3 are 71.1 u g/mL, 100.5 u g/mL, 93.8 u g/mL, 116.6 ug/mL and 58.6 u g/mL, 114.3 u g/mL, 114.3 u g/mL, 90.8 u g/mL respectively. TPs and EGCG have different effects on normal and cancer cells derived of the same orgnize. ICso values of TPs and EGCG against D6 and WI-38 are 71.1 u g/mL, 1786.7 u g/mL and 58.6 U g/mL, 2177.4 u g/mL respectively. Lower concentrition of TPs and EGCG increased the number of WI-38 and higher concentrition of TPs and EGCG also can inhibit the growth of WI-38 cell and is concentration-dependent. The inhibition of lower concentrition of TPs and EGCG is stronger than the inhibition of higher concentrion for cancer cells.Morphological changes in D6 cells after treated with EGCG showed in fluoresent microscopy dyed with Hoechst33258 for lOmin. Typical apoptotic characteristics of D6 cells were determined by fluorescent microscopy and DNA fragment electrophoresis after the cells were treated with EGCG for 80 u g/mL for 48h. The ROS level in cells treated with 80 u g/mL EGCG increases 88.9% than that in control cells indicating that ROS is connective with apoptosis in D6 cells. The results of Caspase 8 test and GST test indicated that they don't join in apoptosis in D6 cells. Further experiments examine the expression of BCL-2 by Western blot and no bands were observed. The mechanism of apoptosis induced by EGCG in D6 cells may be as the following: EGCG induce the increase of ROS level in D6 cells, and the latter induce apoptosis in D6 cells by mitochondria signal transduction pathway.