Gamma-Tocotrienol Slows Diet-Induced Obesity and Improves Insulin Resistance in Animal Model

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Researchers from the University of Florida report that gamma-tocotrienol from red palm oil accumulates in adipose tissues, slowing down high-fat diet-induced obesity and improving insulin sensitivity in mice by inhibiting adipose inflammation.

In the new study, Dr. SK Chung and her team investigated the effects of gamma-tocotrienol on early onset obesity, inflammation, and insulin resistance in mice. The mice were randomly assigned to three different diet groups – low fat (LF), high fat (HF) with 60% calories from fat, or HF mixed with 0.05% gamma-tocotrienol, one of eight different compounds that make up natural vitamin E. Measurements of gamma-tocotrienol concentrations in blood and adipose tissue; effects of gamma-tocotrienol on body weight gain, adipose volume, fasting blood glucose, insulin level and various inflammatory biomarkers were recorded.

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Thrombomodulin Contributes to Gamma Tocotrienol-Mediated Lethality Protection and Hematopoietic Cell Recovery in Irradiated Mice.

Pathak R, Shao L, Ghosh SP, Zhou D, Boerma M, Weiler H, Hauer-Jensen M

PLoS One. 2015 Apr 10;10(4):e0122511

Abstract

Systemic administration of recombinant thrombomodulin (TM) confers radiation protection partly by accelerating hematopoietic recovery. The uniquely potent radioprotector gamma tocotrienol (GT3), in addition to being a strong antioxidant, inhibits the enzyme hydroxy-methyl-glutaryl-coenzyme A reductase (HMGCR) and thereby likely modulates the expression of TM. We hypothesized that the mechanism underlying the exceptional radioprotective properties of GT3 partly depends on the presence of endothelial TM. In vitro studies confirmed that ionizing radiation suppresses endothelial TM (about 40% at 4 hr after 5 Gy γ-irradiation) and that GT3 induces TM expression (about 2 fold at the mRNA level after 5 μM GT3 treatment for 4 hr). In vivo survival studies showed that GT3 was significantly more effective as a radioprotector in TM wild type (TM+/+) mice than in mice with low TM function (TMPro/-). After exposure to 9 Gy TBI, GT3 pre-treatment conferred 85% survival in TM+/+ mice compared to only 50% in TMPro/-. Thus, GT3-mediated radiation lethality protection is partly dependent on endothelial TM. Significant post-TBI recovery of hematopoietic cells, particularly leukocytes, was observed in TM+/+ mice (p = 0.003), but not in TMPro/- mice, despite the fact that GT3 induced higher levels of granulocyte colony stimulating factor (G-CSF) in TMPro/- mice (p = 0.0001). These data demonstrate a critical, G-CSF-independent, role for endothelial TM in GT3-mediated lethality protection and hematopoietic recovery after exposure to TBI and may point to new strategies to enhance the efficacy of current medical countermeasures in radiological/nuclear emergencies.

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δ-Tocotrienol Induces Human Bladder Cancer Cell Growth Arrest, Apoptosis and Chemosensitization through Inhibition of STAT3 Pathway.

Ye C, Zhao W, Li M, Zhuang J, Yan X, Lu Q, Chang C, Huang X, Zhou J, Xie B, Zhang Z, Yao X, Yan J, Guo H.

PLoS One. 2015 Apr 7;10(4):e0122712.

Abstract

Vitamin E intake has been implicated in reduction of bladder cancer risk. However, the mechanisms remain elusive. Here we reported that δ-tocotrienol (δ-T3), one of vitamin E isomers, possessed the most potent cytotoxic capacity against human bladder cancer cells, compared with other Vitamin E isomers. δ-T3 inhibited cancer cell proliferation and colonogenicity through induction of G1 phase arrest and apoptosis. Western blotting assay revealed that δ-T3 increased the expression levels of cell cycle inhibitors (p21, p27), pro-apoptotic protein (Bax) and suppressed expression levels of cell cycle protein (Cyclin D1), anti-apoptotic proteins (Bcl-2, Bcl-xL and Mcl-1), resulting in the Caspase-3 activation and cleavage of PARP. Moreover, the δ-T3 treatment inhibited ETK phosphorylation level and induced SHP-1 expression, which was correlated with downregulation of STAT3 activation. In line with this, δ-T3 reduced the STAT3 protein level in nuclear fraction, as well as its transcription activity. Knockdown of SHP-1 partially reversed δ-T3-induced cell growth arrest. Importantly, low dose of δ-T3 sensitized Gemcitabine-induced cytotoxic effects on human bladder cancer cells. Overall, our findings demonstrated, for the first time, the cytotoxic effects of δ-T3 on bladder cancer cells and suggest that δ-T3 might be a promising chemosensitization reagent for Gemcitabine in bladder cancer treatment.

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γ-Tocotrienol-induced endoplasmic reticulum stress and autophagy act concurrently to promote breast cancer cell death.

Tiwari RV, Parajuli P, Sylvester PW.

Biochem Cell Biol. 2015 Mar 12:1-15.

Abstract

The anticancer effects of γ-tocotrienol are associated with the induction of autophagy and endoplasmic reticulum (ER) stress-mediated apoptosis, but a direct relationship between these events has not been established. Treatment with 40 μmol/L of γ-tocotrienol caused a time-dependent decrease in cancer cell viability that corresponds to a concurrent increase in autophagic and endoplasmic reticulum (ER) stress markers in MCF-7 and MDA-MB-231 human breast cancer cells. γ-Tocotrienol treatment was found to cause a time-dependent increase in early phase (Beclin-1, LC3B-II) and late phase (LAMP-1 and cathepsin-D) autophagy markers, and pretreatment with autophagy inhibitors Beclin-1 siRNA, 3-MA or Baf1 blocked these effects. Furthermore, blockage of γ-tocotrienol-induced autophagy with Beclin-1 siRNA, 3-MA, or Baf1 induced a modest, but significant, reduction in γ-tocotrienol-induced cytotoxicity. γ-Tocotrienol treatment was also found to cause a decrease in mitogenic Erk1/2 signaling, an increase in stress-dependent p38 and JNK1/2 signaling, as well as an increase in ER stress apoptotic markers, including phospho-PERK, phospho-eIF2α, Bip, IRE1α, ATF-4, CHOP, and TRB3. In summary, these finding demonstrate that γ-tocotrienol-induced ER stress and autophagy occur concurrently, and together act to promote human breast cancer cell death.

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A combination of palm oil tocotrienols and citrus peel polymethoxylated flavones does not influence elevated LDL cholesterol and high-sensitivity C-reactive protein levels.

Schuchardt JP, Heine S, Hahn A.

Eur J Clin Nutr. 2015 Apr 1

Abstract

BACKGROUND/OBJECTIVES:

Lipid-lowering and anti-inflammatory effects have been individually described for tocotrienols (TTs) and polymethoxylated flavones (PMFs). This study investigated low-density lipoprotein-cholesterol (LDL-C)- and high-sensitivity C-reactive protein (hsCRP)-reducing effects of combined TT-PMF treatment in low doses in hypercholesterolemic individuals with subclinical inflammation.

SUBJECTS/METHODS:

In the double-blind, placebo-controlled study, 240 Caucasians with LDL-C ⩾3.36 mmol/l and hsCRP ⩾1 mg/l were enrolled and randomized into group S1 (12 mg/day TT and 103 mg/day PMF), group S2 (27 mg/day TT and 32 mg/day PMF) or placebo.

RESULTS:

Twenty-three subjects dropped out of the study, 13 were excluded from the analysis because of lack of compliance. A total of 204 subjects per-protocol analysis were included. After 12 weeks of treatment, no significant differences in LDL-C levels (primary outcome) were observed between groups. LDL-C levels significantly decreased in all intervention groups (S1: -5.2%, S2: -4.8% and P: -4.2%). Total cholesterol and hsCRP (secondary outcome) did not change significantly.

CONCLUSIONS:

PMF-TT supplements had no effect beyond that of placebo on elevated LDL-C and hsCRP levels.European Journal of Clinical Nutrition advance online publication, 1 April 2015; doi:10.1038/ejcn.2015.44.

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Delta-Tocotrienol Suppresses Radiation-Induced MicroRNA-30 and Protects Mice and Human CD34+ Cells from Radiation Injury.

Li XH, Ha CT, Fu D, Landauer MR, Ghosh SP, Xiao M.

PLoS One. 2015 Mar 27;10(3):e0122258

Abstract

We reported that microRNA-30c (miR-30c) plays a key role in radiation-induced human cell damage through an apoptotic pathway. Herein we further evaluated radiation-induced miR-30 expression and mechanisms of delta-tocotrienol (DT3), a radiation countermeasure candidate, for regulating miR-30 in a mouse model and human hematopoietic CD34+ cells. CD2F1 mice were exposed to 0 (control) or 7-12.5 Gy total-body gamma-radiation, and CD34+ cells were irradiated with 0, 2 or 4 Gy of radiation. Single doses of DT3 (75 mg/kg, subcutaneous injection for mice or 2 μM for CD34+ cell culture) were administrated 24 h before irradiation and animal survival was monitored for 30 days. Mouse bone marrow (BM), jejunum, kidney, liver and serum as well as CD34+ cells were collected at 1, 4, 8, 24, 48 or 72 h after irradiation to determine apoptotic markers, pro-inflammatory cytokines interleukin (IL)-1β and IL-6, miR-30, and stress response protein expression. Our results showed that radiation-induced IL-1β release and cell damage are pathological states that lead to an early expression and secretion of miR-30b and miR-30c in mouse tissues and serum and in human CD34+ cells. DT3 suppressed IL-1β and miR-30 expression, protected against radiation-induced apoptosis in mouse and human cells, and increased survival of irradiated mice. Furthermore, an anti-IL-1β antibody downregulated radiation-induced NFκBp65 phosphorylation, inhibited miR-30 expression and protected CD34+ cells from radiation exposure. Knockdown of NFκBp65 by small interfering RNA (siRNA) significantly suppressed radiation-induced miR-30 expression in CD34+ cells. Our data suggest that DT3 protects human and mouse cells from radiation damage may through suppression of IL-1β-induced NFκB/miR-30 signaling.

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Tocotrienol-Rich Fraction (TRF) Suppresses the Growth of Human Colon Cancer Xenografts in Balb/C Nude Mice by the Wnt Pathway.

Zhang JS, Zhang SJ, Li Q, Liu YH, He N, Zhang J, Zhou PH, Li M, Guan T, Liu JR.

PLoS One. 2015 Mar 25;10(3):e0122175.

Abstract

Tocotrienols have been shown many biologic functions such as antioxidant, anti-cancer, maintaining fertility and regulating the immune system and so on. In this study, after feeding with tocotrienol-rich fraction from palm oil (TRF) for 2 weeks, Balb/c nude mice were inoculated human colon SW620 cancer cell and then continued to feed TRF for 4 weeks. At termination of experiments, xenografts were removed and determined the expression of Wnt-pathways related protein by immunohistochemistry or western blotting. Liver tissues were homogenated for determining the levels of antioxidative enzymes activity or malondialdehyde (MDA). The results showed that TRF significantly inhibited the growth of xenografts in nude mice. TRF also affected the activity of antioxidative enzymes in the liver tissue of mice. These changes were partly contributed to activation of wnt pathways or affecting their related protein. Thus, these finding suggested that the potent anticancer effect of TRF is associated with the regulation of Wnt signal pathways.

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