title: alpha-Tocopherol attenuates the cytotoxic effect of delta-tocotrienol in human colorectal adenocarcinoma cells.
abstract: Recent studies have demonstrated that tocotrienol (T3) is superior to tocopherol (Toc) for cancer chemoprevention. However, there is little information on whether Toc influences the anticancer property of T3. In this study, we investigated the influence of Toc on the cytotoxic effects of delta-T3 in DLD-1 human colorectal adenocarcinoma cells. Toc, especially alpha-Toc, attenuated delta-T3-induced cytotoxicity and apoptosis in DLD-1 cells, whereas Toc alone did not exhibit any cytotoxic effect. delta-T3-induced cell cycle arrest and proapoptotic gene/protein expression (e.g., p21, p27, and caspases) were abrogated by alpha-Toc. Furthermore, coadministration of alpha-Toc decreased delta-T3 uptake into DLD-1 cells in a dose-dependent manner. These results indicate that alpha-Toc is not only less cytotoxic to cancer cells, but it also reduces the cytotoxicity of delta-T3 by inhibiting its cellular uptake.
authors.affiliation: Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Shibata
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Nakagawa
authors.forename: Phumon
authors.initials: P
authors.lastname: Sookwong
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Tsuduki
authors.forename: Akira
authors.initials: A
authors.lastname: Asai
authors.forename: Teruo
authors.initials: T
authors.lastname: Miyazawa
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism*; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000378:metabolism*; D006801:Humans; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology; D024502:alpha-Tocopherol / Q000494:pharmacology*
chemical_list: D014810:Vitamin E; C082097:tocotrienol, delta; D024502:alpha-Tocopherol