theaflavin-3-3--digallate and Ovarian-Neoplasms

Theaflavin-3,3'-digallate (TF3) is a unique polyphenol in black tea. Epidemiological studies have proved that black tea consumption decreases the incidence rate of ovarian cancer. Our former research demonstrated that TF3 inhibited human ovarian cancer cells. Nevertheless, the roles of checkpoint kinase 2 (Chk2) and p27 kip1 (p27) in TF3-mediated inhibition of human ovarian cancer cells have not yet been investigated. In the current study, TF3 enhanced the phosphorylation of Chk2 to modulate the ratio of pro/anti-apoptotic Bcl-2 family proteins to initiate intrinsic apoptosis in a p53-independent manner and increased the expression of death receptors to activate extrinsic apoptosis in OVCAR-3 human ovarian carcinoma cells. In addition, TF3 up-regulated the expression of p27 to induce G0/G1 cell cycle arrest in OVCAR-3 cells. Our study indicated that Chk2 and p27 were vital anticancer targets of TF3 and provided more evidence that TF3 might be a potent agent to be applied as adjuvant treatment for ovarian cancer.

Topics: Antioxidants; Apoptosis; Biflavonoids; Camellia sinensis; Carcinoma; Catechin; Cell Line, Tumor; Checkpoint Kinase 2; Cyclin-Dependent Kinase Inhibitor p27; Female; Gene Expression Regulation, Neoplastic; Humans; Ovarian Neoplasms; Proto-Oncogene Proteins c-bcl-2; Signal Transduction; Tea; Tumor Suppressor Protein p53

Ovarian cancer has the highest fatality rate among the gynecologic cancers. The side effects, high relapse rate, and drug resistance lead to low long-term survival rate (less than 40%) of patients with advanced ovarian cancer. Theaflavin-3,3'-digallate (TF3), a black tea polyphenol, showed less cytotoxicity to normal ovarian cells than ovarian cancer cells. We aimed to investigate whether TF3 could potentiate the inhibitory effect of cisplatin against human ovarian cancer cell lines. In the present study, combined treatment with TF3 and cisplatin showed a synergistic cytotoxicity against A2780/CP70 and OVCAR3 cells. Treatment with TF3 could increase the intracellular accumulation of platinum (Pt) and DNA-Pt adducts and enhanced DNA damage induced by cisplatin in both cells. Treatment with TF3 decreased the glutathione (GSH) levels and upregulated the protein levels of the copper transporter 1 (CTR1) in both cells, which led to the enhanced sensitivity of both ovarian cancer cells to cisplatin. The results imply that TF3 might be used as an adjuvant to potentiate the inhibitory effect of cisplatin against advanced ovarian cancer.

Topics: Biflavonoids; Catechin; Cation Transport Proteins; Cell Line, Tumor; Cisplatin; Copper Transporter 1; DNA Adducts; DNA Damage; Drug Synergism; Female; Glutathione; Humans; Ovarian Neoplasms; Up-Regulation

Theaflavin-3, 3'-digallate (TF3) is a black tea polyphenol produced from polymerization and oxidization of the green tea ployphenols epicatechin gallate and (-)-epigallocatechin-3-gallate (EGCG) during fermentation of fresh tea leaves. TF3 has been reported to have anticancer properties. However, the effect of TF3 on tumor angiogenesis and the underlying mechanisms are not clear. In the present study, TF3 was verified to inhibit tumor angiogenesis. Compared with EGCG, TF3 was more potent. TF3 inhibited human ovarian carcinoma OVCAR-3 cell-induced angiogenesis in human umbilical vein endothelial cell model and in chick chorioallantoic membrane model. TF3 reduced tumor angiogenesis by downregulating HIF-1α and VEGF. One of the mechanisms was TF3 inactivated Akt/mTOR/p70S6K/4E-BP1 pathway and Akt/c-Myc pathway. Besides, TF3 suppressed the cleavage of Notch-1, subsequently decreased the expression of c-Myc, HIF-1α and VEGF, and finally the impaired cancer cells induced angiogenesis. Nevertheless, TF3 did not have any influence on the MAPK pathways. Taken together, these findings suggest that TF3 might serve as a potential anti-angiogenic agent for cancer treatment.

Topics: Biflavonoids; Carcinoma; Catechin; Cell Line, Tumor; Female; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Mitogen-Activated Protein Kinase Kinases; Neovascularization, Pathologic; Oncogene Protein v-akt; Ovarian Neoplasms; Proto-Oncogene Proteins c-myc; Receptor, Notch1; Signal Transduction; Vascular Endothelial Growth Factor A

Ovarian cancer is the most lethal gynecological cancer among women worldwide. Adverse side effects and acquired resistance to conventional platinum based chemotherapy are major impediments in ovarian cancer treatment, and drive the development of more selective anticancer drugs that target cancer-specific defects. In this study, theaflavin-3, 3'-digallate (TF3), the major theaflavin monomer in black tea, exhibited a potent growth inhibitory effect on the cisplatin-resistant ovarian cancer A2780/CP70 cells (IC50, 23.81 µM), and was less cytotoxic to a normal ovarian IOSE‑364 cells (IC50, 59.58 µM) than to the cancer cells. Flow cytometry analysis indicated that TF3 induced preferential apoptosis and G2 cell cycle arrest in A2780/CP70 cells with respect to IOSE‑364 cells. TF3 induced apoptosis through both the intrinsic and extrinsic apoptotic pathways, and caused G2 cell cycle arrest via cyclin B1 in A2780/CP70 cells. The p53 protein played an important role in TF3-induced apoptosis and G2 cell cycle arrest. TF3 might upregulate the p53 expression via the Akt/MDM2 pathway. Our findings help elucidate the mechanisms by which TF3 may contribute to the prevention and treatment of platinum-resistant ovarian cancer.

Topics: Apoptosis; Biflavonoids; Catechin; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cisplatin; Drug Resistance, Neoplasm; Female; G2 Phase Cell Cycle Checkpoints; Gene Expression Regulation, Neoplastic; Humans; Ovarian Neoplasms; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-mdm2; Signal Transduction; Tumor Suppressor Protein p53