title: Gamma-tocotrienol suppresses prostate cancer cell proliferation and invasion through multiple-signalling pathways.
abstract: Tocotrienol-rich fraction (TRF) has demonstrated antiproliferative effect on prostate cancer (PCa) cells. To elucidate this anticancer property in PCa cells, this study aimed, first, to identify the most potent isomer for eliminating PCa cells; and second, to decipher the molecular pathway responsible for its activity. Results showed that the inhibitory effect of gamma-tocotrienol was most potent, which resulted in induction of apoptosis as evidenced by activation of pro-caspases and the presence of sub-G(1) cell population. Examination of the pro-survival genes revealed that the gamma-tocotrienol-induced cell death was associated with suppression of NF-kappaB, EGF-R and Id family proteins (Id1 and Id3). Meanwhile, gamma-tocotrienol treatment also resulted in the induction of JNK-signalling pathway and inhibition of JNK activity by a specific inhibitor (SP600125) was able to partially block the effect of gamma-tocotrienol. Interestingly, gamma-tocotrienol treatment led to suppression of mesenchymal markers and the restoration of E-cadherin and gamma-catenin expression, which was associated with suppression of cell invasion capability. Furthermore, a synergistic effect was observed when cells were co-treated with gamma-tocotrienol and Docetaxel. Our results suggested that the antiproliferative effect of gamma-tocotrienol act through multiple-signalling pathways, and demonstrated for the first time the anti-invasion and chemosensitisation effect of gamma-tocotrienol against PCa cells.
authors.affiliation: Davos Life Science Pte. Ltd., Cancer Research Laboratory, 11 Biopolis way, #07-03, The Helios 138667, Singapore.
authors.forename: W N
authors.initials: WN
authors.lastname: Yap
authors.forename: P N
authors.initials: PN
authors.lastname: Chang
authors.forename: H Y
authors.initials: HY
authors.lastname: Han
authors.forename: D T W
authors.initials: DT
authors.lastname: Lee
authors.forename: M T
authors.initials: MT
authors.lastname: Ling
authors.forename: Y C
authors.initials: YC
authors.lastname: Wong
authors.forename: Y L
authors.initials: YL
authors.lastname: Yap
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002839:Chromans / Q000494:pharmacology*; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D009361:Neoplasm Invasiveness; D011471:Prostatic Neoplasms / Q000188:drug therapy*; D015398:Signal Transduction / Q000187:drug effects*; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D002839:Chromans; D014810:Vitamin E; C013649:plastochromanol 8