ABSTRACT
PURPOSE: A constituent of green tea, (-)-epigallocatechin-3-gallate (EGCG), is known to possess anti-cancer properties. In this study, the time-course of the anticancer effects of EGCG on human ovarian cancer cells were investigated to provide insights into the molecular-level understanding of the growth suppression mechanism involved in EGCG-mediated apoptosis and cell cycle arrest. MATERIALS AND METHODS: Three human ovarian cancer cell lines (p53 negative, SKOV-3 cells; mutant type p53, OVCAR-3 cells; and wild type p53, PA-1 cells) were used. The effect of EGCG treatment was studied via a cell count assay, cell cycle analysis, FACS, Western blot and macroarray assay. RESULTS: EGCG exerts a significant role in suppressing ovarian cancer cell growth, showed dose dependent growth inhibitory effects in each cell line and induced apoptosis and cell cycle arrest. The cell cycle was arrested at the G1 phase by EGCG in SKOV-3 and OVCAR-3 cells. In contrast, the cell cycle was arrested in the G1/S phase in PA-1 cells. EGCG differentially regulated the expression of genes and proteins (Bax, p21, Retinoblastoma, cyclin D1, CDK4 and Bcl-XL) more than 2 fold, showing a possible gene regulatory role for EGCG. The continual expression in p21WAF1 suggests that EGCG acts in the same way with p53 proteins to facilitate apoptosis after EGCG treatment. Bax, PCNA and Bcl-X are also important in EGCG-mediated apoptosis. In contrast, CDK4 and Rb are not important in ovarian cancer cell growth inhibition. CONCLUSION: EGCG can inhibit ovarian cancer cell growth through the induction of apoptosis and cell cycle arrest, as well as in the regulation of cell cycle related proteins. Therefore, EGCG-mediated apoptosis could be applied to an advanced strategy in the development of a potential drug against ovarian cancer.
Subject(s)
Humans , Apoptosis , Blotting, Western , Cell Count , Cell Cycle , Cell Cycle Checkpoints , Cell Line , Cyclin D1 , G1 Phase , Ovarian Neoplasms , Proliferating Cell Nuclear Antigen , Retinoblastoma , TeaABSTRACT
PURPOSE: An arsenical compound, As2O3, has been reported to be effective for treating acute leukemia and inducing apoptosis in many different tumor cells. In this study, the ability of As4O6 to suppress cell growth and induce gene expression patterns was tested using a cDNA microarray in HPV16 immortalized cervical carcinoma cells, SiHa cells, along with As2O3. MATERIALS AND METHODS: A novel arsenical compound, As4O6, was designed and its ability to induce cell growth inhibition as well as gene expression profiles along with As2O3 in HPV16 infected SiHa cervical cancer cells was compared. Both As2O3 and As4O6 induced apoptosis in SiHa cells, as determined by DNA ladder formation. To further compare the gene expression profiles between these two drugs, a 384 cDNA microarray system was employed. Also, the gene expression profiles were classified into the Gene Ontology (GO) to investigate apoptosis-related cellular processes. RESULTS: As4O6 was more effective i suppressing the growth of SiHa cells in vitro compared to As2O3. In the case of treatment with As2O3, 41 genes were up- or down- regulated at least 2 fold compared to non-treatment. However, 65 genes were up- or down-regulated by As4O6 treatment. In particular, 27 genes were commonly regulated by both arsenic compounds. Also, the GO analysis indicated that down-regulation of cell-regulatory functions, such as cell cycle, protein kinase activity and DNA repair, induced anti-tumor effect. CONCLUSION: These data support that As4O6 could be more effective than As2O3 in inhibiting the growth of HPV16 infected cervical cancer cells. This appears to be mediated through a unique, but overlapping regulatory mechanism(s), suggesting that the regulated genes and cellular processes could be further used as a new potential drug approach for treating cervical cancer in clinical settings.