title: Apoptogenic effects of black tea on Ehrlich's ascites carcinoma cell.
abstract: Next to water, tea is the most ancient and widely consumed beverage in the world. Epidemiological studies have suggested a cancer protective effect, but the results obtained so far are not conclusive. In the current study, mechanisms of the apoptogenic effect of black tea extract were delineated. Black tea administration to Ehrlich's ascites carcinoma (EAC)-bearing Swiss albino mice caused a significant decrease in the tumor cell count in a dose-dependent manner. Flowcytometric analysis showed an increase in the number of cells in the sub-G(0)/G(1) population signifying tumor cell apoptosis by black tea. These results were further confirmed by nuclear staining that demonstrated distinct morphological features of apoptosis. Our data also revealed an increase in the expression of pro-apoptotic protein p53 in EAC. It is known that upon p53 induction, multiple downstream factors contribute to the decision making between growth arrest and apoptosis. Among those, pro-apoptotic gene Bax is up regulated during p53-mediated apoptosis. On the other hand, p53-mediated growth arrest involves p21 as a major effecter. In our system, increase in p53 expression was followed by moderate expression of p21/Waf-1 and high expression of Bax at protein levels. Interestingly, anti-apoptotic protein Bcl-2 was down regulated resulting in decrease in Bcl-2/Bax ratio. All these observations together signify that black tea-induced apoptogenic signals overrode the growth-arresting message of p21, thereby leading the tumor cells towards death.
authors.affiliation: Bose Institute, P-1/12 CIT Scheme VII M, Kolkata-700 054, India.
authors.forename: Arindam
authors.initials: A
authors.lastname: Bhattacharyya
authors.forename: Tathagata
authors.initials: T
authors.lastname: Choudhuri
authors.forename: Suman
authors.initials: S
authors.lastname: Pal
authors.forename: Sreya
authors.initials: S
authors.lastname: Chattopadhyay
authors.forename: Goutam
authors.initials: G
authors.lastname: K  Datta
authors.forename: Gaurisankar
authors.initials: G
authors.lastname: Sa
authors.forename: Tanya
authors.initials: T
authors.lastname: Das
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002286:Carcinoma, Ehrlich Tumor / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D005434:Flow Cytometry; D051379:Mice; D009368:Neoplasm Transplantation; D010936:Plant Extracts / Q000494:pharmacology*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D013662:Tea; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D051028:bcl-2-Associated X Protein
chemical_list: C494827:Bax protein, mouse; C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D010936:Plant Extracts; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D013662:Tea; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein