Epidemiological studies have highlighted the ability of phytochemicals to reduce the risk of breast cancer by attenuating specific intracellular signaling pathways that regulate cell proliferation and survival. γ-Tocotrienol is a natural form of vitamin E that displays potent anticancer activity at doses that have no discernible toxicity toward normal cells. Sesamin is an abundant phytochemical found in sesame seed oil that also shows antiproliferative and antiangiogenic activity against human breast cancer cells. In this study, the combined treatment of subeffective doses of γ-tocotrienol and sesamin caused a synergistic inhibition of murine +SA mammary epithelial cell growth, as determined by the MTT assay and immunofluorescent Ki-67 staining. Western blot studies revealed that combined low-dose treatment of γ-tocotrienol and sesamin caused a marked reduction in EGF-induced ErbB3 and ErbB4 receptors phosphorylation (activation) and a relatively large decrease in intracellular levels of total and/or phosphorylated c-Raf, MEK1/2, ERK1/2, PI3K, PDK1, Akt, p-NFκB, Jak1, Jak2, and Stat1, as compared to cells treated with only one compound or in the vehicle-treated control group. These findings demonstrate that the synergistic growth inhibitory effects of γ-tocotrienol and sesamin treatment are associated with suppression of EGF-dependent mitogenic signaling in mammary tumor cells and suggest that dietary supplementation with these phytochemicals may provide some benefits in the prevention and/or treatment of breast cancer.
Monthly Archives: November 2012
In 1922, embryologist H M Evans discovered tocopherols (TP) which are needed for human reproduction (Evans and Bishop, 1922; Evans et al., 1974). More than 40 years later, the isolation of tocotrienol (T3) from latex was first reported by R A Morton (Danphy et al., 1965). To date, vitamin E consists of T3 and TP. Together with TP, T3 provides a significant source of anti oxidant activity in all living cells. This common anti oxidant attribute reflects the similarity in chemical structure between T3 and TP, which differ only in their structural side-chain (T3 contains farnesyl while TP has a saturated phytyl side-chain). The common hydrogen atom from the hydroxyl (OH) group on the chromanol ring acts by scavenging the chain-propagating peroxyl free radicals. Depending on the location of the methyl groups on their chromanol ring, T3 and TP can be distinguished as four isomeric forms: alpha (a), beta (b), gamma (g), and delta (d). As TP was discovered much earlier compared to T3, TP has been more widely applied in human nutrition.
Inhibition of Mitochondrial Cytochrome C Release and Suppression of Caspases by Gamma-Tocotrienol Prevent Apoptosis and Delay Aging in Stress-Induced Premature Senescence of Skin Fibroblasts
Makpol S, Abdul Rahim N, Kien Hui C, Wan Ngah WZ.
Oxid Med Cell Longev. 2012;2012:785743
In this study, we determined the molecular mechanism of γ-tocotrienol (GTT) in preventing cellular aging by focusing on its anti-apoptotic effect in stress-induced premature senescence (SIPS) model of human diploid fibroblasts (HDFs). Results obtained showed that SIPS exhibited senescent-phenotypic characteristic, increased expression of senescence-associated β-galactosidase (SA β-gal) and promoted G(0)/G(1) cell cycle arrest accompanied by shortening of telomere length with decreased telomerase activity. Both SIPS and senescent HDFs shared similar apoptotic changes such as increased Annexin V-FITC positive cells, increased cytochrome c release and increased activation of caspase-9 and caspase-3 (P < 0.05). GTT treatment resulted in a significant reduction of Annexin V-FITC positive cells, inhibited cytochrome c release and decreased activation of caspase-9 and caspase-3 (P < 0.05). Gene expression analysis showed that GTT treatment down regulated BAX mRNA, up-regulated BCL2A1 mRNA and decreased the ratio of Bax/Bcl-2 protein expression (P < 0.05) in SIPS. These findings suggested that GTT inhibits apoptosis by modulating the upstream apoptosis cascade, causing the inhibition of cytochrome c release from the mitochondria with concomitant suppression of caspase-9 and caspase-3 activation. In conclusion, GTT delays cellular senescence of human diploid fibroblasts through the inhibition of intrinsic mitochondria-mediated pathway which involved the regulation of pro- and anti-apoptotic genes and proteins.
Gamma-tocotrienol modulation of senescence-associated gene expression prevents cellular aging in human diploid fibroblasts
Makpol S, Zainuddin A, Chua KH, Yusof YA, Ngah WZ.
Clinics (Sao Paulo). 2012;67(2):135-43.
Objective: Human diploid fibroblasts undergo a limited number of cellular divisions in culture and progressively reach a state of irreversible growth arrest, a process termed cellular aging. The beneficial effects of vitamin E in aging have been established, but studies to determine the mechanisms of these effects are ongoing. This study determined the molecular mechanism of γ-tocotrienol, a vitamin E homolog, in the prevention of cellular aging in human diploid fibroblasts using the expression of senescence-associated genes.
Methods: Primary cultures of young, pre-senescent, and senescent fibroblast cells were incubated with γ-tocotrienol for 24 h. The expression levels of ELN, COL1A1, MMP1, CCND1, RB1, and IL6 genes were determined using the quantitative real-time polymerase chain reaction. Cell cycle profiles were determined using a FACSCalibur Flow Cytometer.
Results: The cell cycle was arrested in the G(0)/G(1) phase, and the percentage of cells in S phase decreased with senescence. CCND1, RB1, MMP1, and IL6 were upregulated in senescent fibroblasts. A similar upregulation was not observed in young cells. Incubation with γ-tocotrienol decreased CCND1 and RB1 expression in senescent fibroblasts, decreased cell populations in the G(0)/G(1) phase and increased cell populations in the G(2)/M phase. γ-Tocotrienol treatment also upregulated ELN and COL1A1 and downregulated MMP1 and IL6 expression in young and senescent fibroblasts.
Conclusion: γ-Tocotrienol prevented cellular aging in human diploid fibroblasts, which was indicated by the modulation of the cell cycle profile and senescence-associated gene expression.
Human Blood Outcomes Following Tocotrienol Supplementation – NUTRITION Phase I and Phase IIA
Chandan K Sen, Ph.D. Andrew Slivka, MD Cameron Rink, PhD
Ongoing
Objective: Plan to conduct two trials (I & IIA) to determine the effects of orally supplemented TCT on platelet function and cholesterol.
Study type: Interventional
Study Design: Randomized, Double-blind
Subjects: Phase I – healthy volunteers; Phase IIa- hyperlipidemic subjects
Intervention: Tocotrienol, low dose aspirin
Primary Outcome: 1) Platelet function panel. Blood draw followed by platelet aggregometry.
2) Lipid profile. Blood lipid panel including HDL, LDL, total cholesterol
Secondary Outcome: Tape Stripping Test. HPLC vitamin E analysis of tape strips for compliance
Methodology: We plan to conduct two trials (I & IIA) to determine the effects of orally supplemented TCT on platelet function and cholesterol. Phase I subjects will be healthy volunteers, recruited by an advertisement. Phase IIA subjects will be hyperlipidemic (having high cholesterol), and will be referred to us by their Wound Care Center Physicians. Patients will be randomized to receive placebo pills, (400 or 800 mg) TCT pills, low-dose 81 mg aspirin (commonly used for secondary prevent stroke), or TCT and aspirin together. potential subjects for Phase-I who meet study criteria and agree to participate will be in the study for 6 months and have following study related procedures,blood draw total 3 times, tape stripping(non-invasive procedure) and blood pressure measurement in each visit (every month). For participants in Phase-IIA will have total 5 times blood draw, tape stripping and blood pressure measurement and participants will be in the study for 12 months.
A Phase I Dose-Escalation Study of the Safety, Pharmacokinetics, and Pharmacodynamics of Vitamin E δ-Tocotrienol Administered to Subjects With Resectable Pancreatic Exocrine Neoplasia
Gregory Springett, M.D., Ph.D.H., Moffitt Cancer Center (USA)
Ongoing
Objective: The purpose of this study is to determine the safest dose of the study drug Vitamin E delta-tocotrienol, how often it should be taken, and how well people with pancreatic tumors tolerate Vitamin E delta-tocotrienol.
Study Type: Interventional
Study Design: Open Label, Safety Efficacy Study
Subjects: Patients with resectable pancreatic neoplasia
Intervention: Vitamin E delta-tocotrienol
Primary Outcome: To determine the recommended Phase II dose of Vitamin E δ-Tocotrienol which will be defined as the biologic effective dose (BED) which induces significant apoptosis in the pancreatic neoplastic cells of resected tumor specimens following oral administration of Vitamin E δ-Tocotrienol twice daily for 14 (± 2)days prior to surgery, and one dose the day of surgery.
Secondary Outcome: To characterize the safety and tolerability of Vitamin E δ-Tocotrienol when orally administered at up to 5.6 times the predicted biological effective dose (1600mg twice daily) for 14 (± 2) consecutive days and one dose the day of surgery in patients with pancreatic neoplasia.
Methodology: This study consists of the following: (1) A Pre-Treatment Period in which participants are consented and qualified for the study; (2) A Study Treatment Period in which participant will receive Vitamin E δ-Tocotrienol administered orally twice daily for 14 (±2) consecutive days and once on the day of surgery, with associated pharmacokinetic and pharmacodynamic sampling; (3) A Post Treatment Period in which laboratory and physical examinations are performed. Adverse events will be recorded throughout the study.