Black tea protects immunocytes from tumor-induced apoptosis by changing Bcl-2/Bax ratio.
It is known that cancer is associated with altered immune function. We demonstrated earlier that black tea inhibits tumor growth in a dose-dependent manner. Here, we report that apoptosis was the cause of immunocyte death in Ehrlich's ascites carcinoma (EAC)-bearing mice and anti-tumor dose of black tea restored EAC-induced immunosuppression by inhibiting apoptosis. A search for the molecular mechanism revealed that EAC burden increased the expression of the pro-apoptotic proteins p53 and Bax in splenic lymphocytes although did not change the level of pro-proliferative protein Bcl-2. Interestingly, anti-tumor dose of black tea down-regulated p53, decreased Bax while augmenting Bcl-2 in these cells. As a result, Bcl-2/Bax ratio was increased and the immunocytes were protected from tumor-induced apoptosis. Thus, unlike many other anti-cancer agents, black tea is not only devoid of immunosuppressive effect but also acts as immuno-restorer in tumor-bearing host. These results, thus, raise the possibility of inclusion of black tea in successful therapeutic regimen against cancer.
Bhattacharyya
Arindam
A
Bose Institute, P-1/12 CIT Scheme VII M, Kolkata 700 054, India.
Mandal
Debaprasad
D
Lahiry
Lakshmishri
L
Sa
Gaurisankar
G
Das
Tanya
T
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002286:Carcinoma, Ehrlich Tumor / Q000276:immunology* / Q000473:pathology / Q000517:prevention & control*; D002453:Cell Cycle / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic; D007165:Immunosuppression Therapy; D008214:Lymphocytes / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D013154:Spleen / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D013662:Tea; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D051028:bcl-2-Associated X Protein
C494827:Bax protein, mouse; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D013662:Tea; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein