The present study investigated the effects of a preparation of a g-tocopherol-rich mixture of tocopherols (g-TmT) on chemically induced lung tumorigenesis in female A/J mice and the growth of H1299 human lung cancer cell xenograft tumors. In the A/J mouse model, the lung tumors were induced by either 4-(methylnitrosamino)- 1-(3-pyridyl)-1-butanone (NNK; intraperitoneal injections with 100 and 75 mg/kg on Week 1 and 2, respectively) or NNK plus benzo[a]pyrene (B[a]P) (8 weekly gavages of 2 mmole each from Week 1 to 8). The NNK plus B[a]P treatment induced 21 tumors per lung on Week 19; dietary 0.3% g-TmT treatment during the entire experimental period significantly lowered tumor multiplicity, tumor volume and tumor burden (by 30, 50 and 55%, respectively; P < 0.05). For three groups of mice treated with NNK alone, the g-TmT diet was given during the initiation stage (Week 0 to 3), post-initiation stage (Week 3 to 19) or the entire experimental period, and the tumor multiplicity was reduced by 17.8, 19.7 or 29.3%, respectively (P < 0.05). g-TmT treatment during the tumor initiation stage or throughout the entire period of the experiment also significantly reduced tumor burden (by 36 or 43%, respectively). In the xenograft tumor model of human lung cancer H1299 cells in NCr-nu/nu mice, 0.3% dietary g-TmT treatment significantly reduced tumor volume and tumor weight by 56 and 47%, respectively (P < 0.05). In both the carcinogenesis and tumor growth models, the inhibitory action of g-TmT was associated with enhanced apoptosis and lowered levels of 8-hydroxydeoxyguanine, g-H2AX and nitrotyrosine in the tumors of the g-TmT-treated mice. In cell culture, the growth of H1299 cells was inhibited by tocopherols with their effectiveness following the order of d-T > g-TmT > g-T, whereas a-T was not effective. These results demonstrate the inhibitory effect of g-TmT against lung tumorigenesis and the growth of xenograft tumors of human lung cancer cells. The inhibitory activity may be due mainly to the actions of d-T and g-T.
Blog Archives
In vivo evidence of gamma-tocotrienol as a chemosensitizer in the treatment of hormone-refractory prostate cancer
Yap WN, Zaiden N, Luk SY, Lee DT, Ling MT, Wong YC, Yap YL.
Pharmacology. 2010;85(4):248-58. Epub 2010 Apr 7.
Gamma-Tocotrienol (gammaT3) is known to selectively kill prostate cancer (PCa) cells and to sensitize the cells to docetaxel (DTX)-induced apoptosis. In the present study, the pharmacokinetics of gammaT3 and the in vivo cytotoxic response of androgen-independent prostate cancer (AIPCa) tumor following gammaT3 treatment were investigated. Here, we investigated these antitumor effects for PCa tumors in vivo. The pharmacokinetic and tissue distribution of gammaT3 after exogenous gammaT3 supplementation were examined. Meanwhile, the response of the tumor to gammaT3 alone or in combination with DTX were studied by real-time in vivo bioluminescent imaging and by examination of biomarkers associated with cell proliferation and apoptosis. After intraperitoneal injection, gammaT3 rapidly disappeared from the serum and was selectively deposited in the AIPCa tumor cells. Administration of gammaT3 alone for 2 weeks resulted in a significant shrinkage of the AIPCa tumors. Meanwhile, further inhibition of the AIPCa tumor growth was achieved by combined treatment of gammaT3 and DTX (p < 0.002). The in vivo cytotoxic antitumor effects induced by gammaT3 seem to be associated with a decrease in expression of cell proliferation markers (proliferating cell nuclear antigen, Ki-67 and Id1) and an increase in the rate of cancer cell apoptosis [cleaved caspase 3 and poly(ADP-ribose) polymerase]. Additionally, the combined agents may be more effective at suppressing the invasiveness of AIPCa. Overall, our results indicate that gammaT3, either alone or in combination with DTX, may provide a treatment strategy that can improve therapeutic efficacy against AIPCa while reducing the toxicity often seen in patients treated with DTX.
Enhanced antiproliferative and apoptotic response to combined treatment of gamma-tocotrienol with erlotinib or gefitinib in mammary tumor cells
Bachawal SV, Wali VB, Sylvester PW.
BMC Cancer. 2010 Mar 8;10:84.
Background: Aberrant ErbB receptor signaling is associated with various types of malignancies. gamma-Tocotrienol is a member of the vitamin E family of compounds that displays potent anticancer activity that is associated with suppression in ErbB receptor phosphorylation and mitogenic signaling. Erlotinib and gefitinib are tyrosine kinase inhibitors that block ErbB1 receptor activation, whereas trastuzumab is a monoclonal antibody that has been designed to specifically inhibit ErbB2 receptor activation. However, the clinical effectiveness of these agents have been disappointing because of cooperation between different ErbB family members that can rescue cancer cells from agents directed against a single ErbB receptor subtype. It was hypothesized that targeting multiple ErbB receptor subtypes with combined treatment of gamma-tocotrienol and ErbB receptor inhibitors would provide greater anticancer effects than monotherapy targeting only a single ErbB receptor subtype.
Methods: Highly malignant mouse +SA mammary epithelial cells were maintained in culture on serum-free defined media containing 10 ng/ml EGF as a mitogen. Cell viability wase determined by MTT assay, whereas Western blot and immunofluorescent staining was used to determine treatmenteffects on ErbB receptor subtype level and activation. Treatment-induced apoptosis was determined using annexin V staining and Western blot analysis of cleaved caspase-3 and PARP levels.
Results: Treatment with 3.5 microM gamma-tocotrienol, 0.5 microM erlotinib or 1.0 microM gefitinib alone, significantly inhibited +SA tumor cell growth. Combined treatment with subeffective doses of erlotinib (0.25 microM) or gefitinib (0.5 microM) with subeffective doses of gamma-tocotrienol(0.5-3.0 microM) significantly inhibited the growth and induced apoptosis in a dose-responsive manner. Trastuzumab treatment alone or in combination had no effect on +SA cell growth and viability. Combined treatment of gamma-tocotrienol with erlotinib or gefitinib also cause a large decrease in ErbB3, ErbB4, and to a lesser extent ErbB2 receptor levels, and EGF-dependent ErbB2-4 tyrosine phosphorylation (activation), but had no effect on ErbB1 receptor levels or activation.
Conclusion: Combination treatment of gamma-tocotrienol with specific ErbB receptor inhibitors is more effective in reducing mammary tumor cell growth and viability than high dose monotherapy, suggesting that targeting multiple ErbB receptors with combination therapy may significantly improve the therapeutic response in breast cancer patients.
Inhibitory effects of gamma-tocotrienol on invasion and metastasis of human gastric adenocarcinoma SGC-7901 cells
Liu HK, Wang Q, Li Y, Sun WG, Liu JR, Yang YM, Xu WL, Sun XR, Chen BQ.
J Nutr Biochem. 2010 Mar;21(3):206-13. Epub 2009 Feb 5.
Natural vitamin E is a mixture of two classes of compounds, tocopherols and tocotrienols. Recent research has revealed that tocotrienols, especially gamma-tocotrienol, exhibit not only the same antioxidant ability as tocopherols, but also remarkable anticancer capacity in cancer cell lines. In this study, the invasion and metastatic capacities of gastric adenocarcinoma SGC-7901 cells and the correlation with antimetastasis mechanisms induced by gamma-tocotrienol were explored. The results showed the inhibitory effects of gamma-tocotrienol at doses of 15, 30, 45 and 60 mumol/L for 48 h on cell migration and cell matrigel invasion; activities of matrix metalloproteinase (MMPs) increased in SGC-7901 cells when compared to the control group (P<.05 or P<.01). An increasing trend in the chemotactic responses to fibronectin (FN) in SGC-7901 cells was found in the gamma-tocotrienol treatments. SGC-7901 cell attachment decreased in the gamma-tocotrienol-treated groups in comparison with the control group (P<.01). The mRNA expressions of MMP-2 and MMP-9 showed that gamma-tocotrienol significantly reduced the matrigel invasion capability through down-regulation of the mRNA expressions of MMP-2 and MMP-9 (P<.01), and up-regulation of tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2 in SGC-7901 cells by treatment with gamma-tocotrienol for 48 h (P<.05). gamma-Tocotrienol also significantly increased the mRNA expression of nm23-H1 in SGC-7901 cells (P<.01). These findings suggest a potential mechanism of gamma-tocotrienol-mediated antitumor metastasis activity and indicate the role of vitamin E as potential chemopreventative agents against gastric cancer.
Nanomolar vitamin E alpha-tocotrienol inhibits glutamate-induced activation of phospholipase A2 and causes neuroprotection
Khanna S, Parinandi NL, Kotha SR, Roy S, Rink C, Bibus D, Sen CK.
J Neurochem. 2010 Mar;112(5):1249-60. Epub 2009 Dec 17.
Our previous works have elucidated that the 12-lipoxygenase pathway is directly implicated in glutamate-induced neural cell death, and that such that toxicity is prevented by nM concentrations of the natural vitamin E alpha-tocotrienol (TCT). In the current study we tested the hypothesis that phospholipase A(2) (PLA(2)) activity is sensitive to glutamate and mobilizes arachidonic acid (AA), a substrate for 12-lipoxygenase. Furthermore, we examined whether TCT regulates glutamate-inducible PLA(2) activity in neural cells. Glutamate challenge induced the release of [(3)H]AA from HT4 neural cells. Such response was attenuated by calcium chelators (EGTA and BAPTA), cytosolic PLA(2) (cPLA(2))-specific inhibitor (AACOCF(3)) as well as TCT at 250 nM. Glutamate also caused the elevation of free polyunsaturated fatty acid (AA and docosahexaenoic acid) levels and disappearance of phospholipid-esterified AA in neural cells. Furthermore, glutamate induced a time-dependent translocation and enhanced serine phosphorylation of cPLA(2) in the cells. These effects of glutamate on fatty acid levels and on cPLA(2) were significantly attenuated by nM TCT. The observations that AACOCF(3), transient knock-down of cPLA(2) as well as TCT significantly protected against the glutamate-induced death of neural cells implicate cPLA(2) as a TCT-sensitive mediator of glutamate induced neural cell death. This work presents first evidence recognizing glutamate-induced changes in cPLA(2) as a novel mechanism responsible for neuroprotection observed in response to nanomolar concentrations of TCT.
Tocotrienols inhibited growth and induced apoptosis in human HeLa cells through the cell cycle signaling pathway
Wu SJ, Ng LT.
Integr Cancer Ther. 2010 Mar;9(1):66-72. Epub 2010 Feb 11.
Tocotrienols of palm oil have been shown to possess potent neuroprotective, antioxidative, anticancer, and cholesterol-lowering activities. In this study, the authors examined the antiproliferative effects of alpha-, gamma- and delta-tocotrienols (alphaT3, gammaT3, and deltaT3), and alpha-tocopherol (alphaT) in human cervical carcinoma (HeLa) cells. Their mechanism(s) of action on cell cycle signaling pathway were also investigated. RESULTS: 3.19 +/- 0.05 microM) and gammaT3 (IC(50): 2.85 +/- 0.07 microM) was more potent than deltaT3 (IC(50): >100 microM) and alphaT (IC(50): 69.46 +/- 3.01 microM). Both alphaT3 and gammaT3 also demonstrated a dose-dependent and time-dependent induction of cell death.They caused cell cycle arrest at G2/M phase and triggered apoptosis as displayed by the externalization of annexin V-targeted phosphatidylserine and accumulation of sub-G1 peak. At a concentration of 3 microM, alphaT3 downregulated the expression of cyclin D3, p16, and CDK6, while having no effect on cyclin D1, p15, p21, p27, and CDK4 expression. However, gammaT3 showed no effect on these proteins. The induction of HeLa cell apoptosis by alphaT3 and gammaT3 appeared to be associated with the expression of IL-6, but not the other cytokines (IFN-gamma, IL-2, and IL-10).Taken together, the results suggest that alphaT3 and gammaT3 are more effective than deltaT3 and alphaT in inhibiting HeLa cell proliferation, and their mode of action could be through the upregulation of IL-6, and the downregulation of cyclin D3, p16, and CDK6 expression in the cell cycle signaling pathway.
Vitamin E is found to reverse the effects of nicotine on bone and this study aimed to determine its mechanism. Male Sprague Dawley rats were divided into four groups and treated for 3 months: Group 1 was the control group (RC). Groups 2 (N), 3 (N+TT) and 4 (N+ATF) received nicotine 7 mg/kg throughout the treatment period. In addition, groups 3 and 4 received tocotrienol 60 mg/kg and alpha-tocopherol 60 mg/kg respectively during months 2 and 3. Parameters measured were serum osteoprotegerin (OPG), serum receptor activator of nuclear factor kappa B ligand (RANKL), femoral and lumbar bone calcium content and body weight. Nicotine did not affect OPG or RANKL levels but reduced bone calcium content suggesting the calcium loss is not due to increase osteoclastogenesis. OPG was increased in N+ATF while RANKL was slightly increased in N+TT. Both vitamin E supplements restored bone calcium loss induced by nicotine. Nicotine impaired weight gain in all treatment groups starting week 4 however, N+TT group was comparable to RC from week 6 onwards. Bone protective effects of ATF, but not TT, may be partly due to inhibition of osteoclastogenesis.
Tocotrienol (T3) is an unsaturated form of natural vitamin E that has been focused on because of its potential health benefits (i.e., antioxidative, antihypercholesterolemic, and antiangiogenic effects). The presence of T3 in some plant sources (e.g., rice bran and palm oil) is known, but its distribution in other edible sources and its daily intake remain unclear. In this study, we aimed at clarifying the distribution of T3 in various food sources and estimating the daily T3 intake of Japanese population. T3 contents of 242 food items and 64 meal items were measured by using normal-phase HPLC with fluorescence detection. As for the results, T3 contents were nondetectable to 12 mg T3/kg wet wt of food items, and nondetectable to 1.3 mg T3/item of processed (cooked) meal. Accordingly, the daily intake of T3 was estimated as 1.9-2.1 mg T3/day/person. The estimated daily intake of T3 appears rather low compared with the intake of tocopherol (8-10 mg/day/person as reported in the Japanese National Nutrition Survey), and additional T3 is important for its therapeutic aspects.
BACKGROUND AND AIMS: Intake of the antioxidant vitamins C and E lowers the oxidative stress. The study aimed to determine plasma concentrations of vitamin C and tocotrienols after supplementation of both vitamins in young male adults.
MATERIALS AND METHODS: A total of 64 police recruits were randomly assigned to one of these groups: (a) 500 mg vitamin C (Vitamin C), (b) 200 mg Tocovid (Tocotrienol), (c) combination of 500 mg vitamin C and 200 mg Tocovid (Combination) or (d) placebo (Placebo) for eight-weeks of supplementation followed by six-week washout period.
RESULTS: In Combination group, mean plasma vitamin C concentration significantly increased from baseline 2.86 +/- 1.19 mg/L to 10.37 +/- 1.29 mg/L and 15.63 +/- 1.27 mg/L after four- and eight-week supplementation, respectively. The corresponding figures for alpha-, delta- and gamma-tocotrienols were 9.9 +/- 2.5 ng/ml to 104.1 +/- 19.8 ng/ml and 112.8 +/- 38.0 ng/ml; 2.5 +/- 0.9 ng/ml to 29.9 +/- 7.0 ng/ml and 17.9 +/- 4.7 ng/ml; 19.2 +/- 3.1 ng/ml to 75.2 +/- 24.1 ng/ml and 161.7 +/- 49.9 ng/ml, respectively. In Vitamin C group, plasma vitamin C concentrations were significantly increased. Conversely, concentration of plasma vitamin C in Tocotrienol group increased from baseline of 2.72 +/- 0.20 mg/L to 6.80 +/- 0.63 mg/L and 8.9 +/- 0.77 mg/L respectively. Plasma concentrations of alpha-, delta- and gamma-tocotrienols in this group were significantly elevated. After 6-week washout period, all the elevated concentrations returned to basal levels.
Vitamin E, like tocotrienols and tocopherols, is constituted of compounds essential for animal cells. Vitamin E is exclusively synthesized by photosynthetic eukaryotes and other oxygenic photosynthetic organisms such as cyanobacteria. In order to prevent lipid oxidation, the plants mainly accumulate tocochromanols in oily seeds and fruits or in young tissues undergoing active cell divisions. From a health point of view, at the moment there is a great interest in the natural forms of tocochromanols, because they are considered promising compounds able to maintain a healthy cardiovascular system and satisfactory blood cholesterol levels. Some evidence suggests that the potency of the antioxidant effects may differ between natural or synthetic source of tocochromanols (vitamin E).