Studies Of The Anticancer Effect Of EGCG And Its Influence On IGF System To Prostate Carcinoma

Background:Prostate cancer is recogninzed as the most common solid neoplasm in Eurpean and American male, and is currently the second most common cause of cancer death in men. The incidence of prostate cancer is lower in China than in western world, but is climbing rapitly year by year. Prostate cancer affects the health of elderly men seariously. The management of prostate cancer plays an active role in urological reseach field.Numerous epidemiologic and experimental studies indicate that, the culture of tea consumption is related in the low risk of prostate cancer in China, and that the change of life style such as tea consumption is highly related to the changing epidemiologic pattern of prostate cancer. Tea and its constituents played an important role in the development of prostate cancer.EGCG is a major biological active component of green tea. Many studies have found that tea inhibits both the development and growth of various types of human malignancies, including prostate, skin, stomach, colon, breast, liver, lung,et al. By far, the mechanism of the anticancer mechanism of EGCG remains unclear. In present, there are many studies still trying to use EGCG in chemoprevention and/or treatment of prostate cancer. Evidence showed, the anticancer mechanism of tea and its constituents is multiple, including induction of apoptosis, cell cycle arrest, signal transduction, inhibit proliferation, anti-oxidant effect and so on.Insulin like factor(IGF) and its signal system plays a critical role in numerous types of human malignancies. Plasma markers of IGF family usually unnormally change in various cancer patients, proteins of the IGF family is also frequently found over expressed in various types of cancer. It may be a marker of cancer diagnose and a potential moleculer target for treatment and prevention of proatete cancer. Studies indicate that EGCGhave important effects on IGF system.In order to study the anti cancer effect of EGCG, and the relationship between its anticancer mechanism and the IGF system, we propose a hypothesis:EGCG can inhibit proliferation, induce apoptosis in prostate cancer cells, via alter the activation of IGF system, reduce the autocrine/paracrine loops,.We measured IGF-Ⅰand IGF-Ⅱlevels in Pca patient, BPH patient and Healthy prostate population using ELISA kit, obsearved the anticancer effect of EGCG in human prostate cancer PC3 cell lines in vitro experiment, and furthermore explored the anticancer mechanism of EGCG on modulate IGF signal system and effect on the expression of downstream signaling molecules. Objective To study the serum IGF-Ⅰand IGF-Ⅱlevels in prastate cancer patients,and the relationship between IGF-Ⅰ, IGF-Ⅱlevels and prastate cancer.Methods The levels of serum IGF-Ⅰand IGF-Ⅱwere detected by ELISA kit in 28 cases of PCa and 20 cases of BPH,20 cases of healthy prostate men as controls. The relevance between the serum IGF-Ⅰand IGF-Ⅱlevels and its clinical significance were studied.Results The serum IGF-Ⅰlevel (491.6±74.1ng/ml) were significantly higher in prostate cancer patients than those in BPH (296.0±87.8ng/ml) and in controls (232.1±95.7ng/ml), the difference is statistically significant(P<0.05). The serum IGF-Ⅱlevel (257.7±62.9ng/ml) in prostate cancer patients were significantly higher than those in BPH (161.0±52.4ng/ml) and in controls (160.8±59.2ng/ml), the difference is statistically significant(P<0.05). Serum IGF-Ⅱlevel were higher in high risk prostate cancer patient than in low risk patient, and the difference is statistically significant (P<0.05). There was no significantly diferrence between serum IGF-Ⅰlevels in high and low risk prostate cancer patient(P> 0.05). There was no significantly diferrence between serum IGF-Ⅰ, IGF-Ⅱlevels in BPH and controls(P > 0.05).Conclusion1. The serum IGF-Ⅰand IGF-Ⅱlevels were correlated with prostate cancer risk, it may be a marker to prognose high risk population.2. The serum IGF-Ⅱlevels were correlated with prostate cancer progress risk, it may be a useful marker to evaluat progression and prognosis. Objective The investigate the effect of EGCG on growth inhibition of prostate cancer cell line PC3.Methods The effect of EGCG on human prostate cancer PC3 cells was evaluated with varying concentration of EGCG treatment for 24-72 hours by MTT assay. The cell apoptosis of human prostate cancer PC3 cells was determined with the indicated concentration of EGCG treatment for 24-72 hours by flow cytometry, the apoptosis index was detected.Results The effect of EGCG on human prostate cancer PC3 cells was evaluated with varying concentration of EGCG (0,20,40,60ng/ml) treatment for 24-72 hours by MTT assay.20ng/ml EGCG significantly inhibit human prostate cancer PC3 cell proliferation(P< 0.001), the cell mean inhibit ratio is 27.7%. The inhibit ratio rises as the EGCG concentration and the time rises, and the inhibit ratio shows a dose-dependent manner and a time-dependent manner. The cell apoptosis of human prostate cancer PC3 cells was determined with the indicated concentration of EGCG treatment for 24-72 hours by flow cytometry The cell apoptosis index with EGCG treatment at concentrations of Ong/ml(control) was 1.37±0.006%, EGCG 20ng/ml was 2.82±0.018%, 40ng/ml 3.45±0.022%,60ng/ml 5.25±0.024%; each concantration group increased significantly compared with control group(P<0.05), AI shows a dose-dependent manner and a time-dependent manner.Conclusion1. EGCG treatment resulted in a significant dose-dependent and time-dependent inhibition in the proliferation of PC3 cells. 2. EGCG treatment resulted in a significant dose-dependent and time-dependent apoptosis induced of PC3 cells. Objective To investigate the molecular biological mechanism of inhibition and the effect on IGF system of EGCG in PC3 cell line.Methods We examined the IGF-Ⅰ, IGF-Ⅱlevels of cell free medium collected from various concentration of EGCG treated PC3 cell lines. Then, in a serier of cells treated with IGF-Ⅰ, IGF-Ⅱand/or EGCG, we detected the expressions of IGF-Ⅰ, IGF-ⅡmRNA by semi-quantitative RT-PCR, also the expressions of p-IGF-ⅠβPR, p-AKT protein by Western blot.Results The IGF-Ⅰ, IGF-Ⅱlevels of cell free medium showed that PC3 cell secreted signicant amounts of both IGF-Ⅰand IGF-Ⅱto the growth medium when cells were cultured. EGCG can inhibit the secretion(P<0.05), and the inhibition is both does-dependent and time-dependent. Semi-quantitive RT-PCR demonstrated that the expression ratio of IGF-ⅠmRNA was 0.623±0.045(control), 0.443±0.015(IGF-Ⅰ),0.193±0.031(IGF-Ⅱ),0.670±0.050(IGF-Ⅰ+EGCG), 0.193±0.021(IGF-Ⅱ+EGCG),0.193±0.038(EGCG), respectively,and the expression ratio of IGF-ⅠmRNA was significant decreased in EGCG treated groups(P<0.01) with the presence or absence of IGF-Ⅰ/IGF-Ⅱ. The expression ratio of IGF-ⅡmRNA was 0.216±0.052(control), 0.294±0.041(IGF-Ⅰ),0.260±0.014(IGF-Ⅱ),0.117±0.030(IGF-Ⅰ+EGCG), 0.108±0.033(IGF-Ⅱ+EGCG),0.097±0.021(EGCG), respectively, and a significantly increased expression ratio was observed in IGF-Ⅰ/IGF-Ⅱ groups compared with control group(P<0.05), The expression ratio of IGF-ⅡmRNA was significant decreased in EGCG treated groups(P<0.01) with the presence or absence of IGF-Ⅰ/IGF-Ⅱ. Western blot demonstrated that the expression ratio of p-IGF-ⅠβR was significantly increased in IGF-Ⅰ/IGF-Ⅱstimulate groups(P<0.05), and was significant decreased in EGCG treated groups(P<0.01) with the presence or absence of IGF-Ⅰ/IGF-Ⅱ. The expression ratio of p-AKT was slightly increased in IGF-Ⅰ/IGF-Ⅱstimulate groups(P>0.05), and was significant decreased in EGCG treated groups(P<0.05) with the presence or absence of IGF-Ⅰ/IGF-Ⅱ.Conclusion1. PC3 cell secreted a signicant amounts of both IGF-Ⅰand IGF-Ⅱinto the growth medium when cells were cultured. EGCG can inhibit the secretion in a does-dependent and time-dependent manner.2. Exogenous IGF-Ⅰ/IGF-Ⅱcaused a significantly increase in the expression of IGF-Ⅰand IGF-ⅡmRNAs. EGCG caused a decrease in the expression of IGF-Ⅰand IGF-ⅡmRNAs with the presence or absence of exogenous IGF-Ⅰ/IGF-Ⅱ.3. Exogenous IGF-Ⅰ/IGF-Ⅱcaused a significantly increase in the expression of p-IGF-ⅠβR protein. EGCG caused a decrease in the expression of p-IGF-ⅠβR and p-AKT proteins with the presence or absence of exogenous IGF-Ⅰ/IGF-Ⅱ.