gamma-Tocotrienol induces mitochondria-mediated apoptosis in human gastric adenocarcinoma SGC-7901 cells

Development of rice bran-derived nanoparticles with excellent anti-cancer activity and their application for peritoneal dissemination

BACKGROUND

Rice bran a by-product of the rice milling process is currently underutilized. Recent studies have shown that plant-derived nanoparticles (pdNPs) can be mass-produced at a low cost and exhibit biological and therapeutic activities. Rice bran contains various anti-cancer compounds, including γ-oryzanol and γ-tocotrienol, and rice bran-derived nanoparticles (rbNPs) can be employed as novel therapeutic agents for cancer treatment.

RESULTS

Koshihikari rice bran was suspended in water, and the suspension was centrifuged and filtered through a 0.45-µm-pore size syringe filter. The filtrate was ultracentrifuged, and the precipitates were suspended to obtain rbNPs. The rbNPs were negatively charged exosome-like nanoparticles with an average diameter of approximately 130 nm. The rbNPs exhibited cytotoxic activities against cancer cells but not against normal cells. The cytotoxic activity of rbNPs to murine colon adenocarcinoma colon26 cells was significantly greater than DOXIL® or other pdNPs. The rbNPs induced cell cycle arrest and apoptosis, and reduced the expression of proliferative proteins, including β-catenin and cyclin D1. Intraperitoneal injections of rbNPs into mice bearing peritoneal dissemination of colon26 cells significantly suppressed tumor growth with no significant adverse effects.

CONCLUSION

These results indicated that rbNPs are promising nanoparticles, hold significant potential for anti-cancer applications, and are expected to play a vital role in cancer treatment.

Integrated Microbiota and Metabolite Changes following Rice Bran Intake during Murine Inflammatory Colitis-Associated Colon Cancer and in Colorectal Cancer Survivors

Dietary rice bran-mediated inhibition of colon carcinogenesis was demonstrated previously for carcinogen-induced rodent models via multiple anti-cancer mechanisms. This study investigated the role of dietary rice bran-mediated changes to fecal microbiota and metabolites over the time course of colon carcinogenesis and compared murine fecal metabolites to human stool metabolic profiles following rice bran consumption by colorectal cancer survivors (NCT01929122). Forty adult male BALB/c mice were subjected to azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colitis-associated colon carcinogenesis and randomized to control AIN93M (n = 20) or diets containing 10% w/w heat-stabilized rice bran (n = 20). Feces were serially collected for 16S rRNA amplicon sequencing and non-targeted metabolomics. Fecal microbiota richness and diversity was increased in mice and humans with dietary rice bran treatment. Key drivers of differential bacterial abundances from rice bran intake in mice included Akkermansia, Lactococcus, Lachnospiraceae, and Eubacterium xylanophilum. Murine fecal metabolomics revealed 592 biochemical identities with notable changes to fatty acids, phenolics, and vitamins. Monoacylglycerols, dihydroferulate, 2-hydroxyhippurate (salicylurate), ferulic acid 4-sulfate, and vitamin B6 and E isomers significantly differed between rice bran- and control-fed mice. The kinetics of murine metabolic changes by the host and gut microbiome following rice bran consumption complemented changes observed in humans for apigenin, N-acetylhistamine, and ethylmalonate in feces. Increased enterolactone abundance is a novel diet-driven microbial metabolite fecal biomarker following rice bran consumption in mice and humans from this study. Dietary rice bran bioactivity via gut microbiome metabolism in mice and humans contributes to protection against colorectal cancer. The findings from this study provide compelling support for rice bran in clinical and public health guidelines for colorectal cancer prevention and control.

Quercetin Improves Mitochondrial Function and Inflammation in H2O2-Induced Oxidative Stress Damage in the Gastric Mucosal Epithelial Cell by Regulating the PI3K/AKT Signaling Pathway

Functional dyspepsia (FD) is one of the most common functional gastrointestinal disorders, the therapeutic strategy of which it is limited due to its complex pathogenesis. Oxidative stress-induced damage in gastric mucosal epithelial cells is related to the pathogenesis and development of FD. Quercetin (Que) is one of the active ingredients of Zhishi that showed antioxidant, antiapoptotic, and anti-inflammatory effects. The aim of this study is to investigate the effect of Que on oxidative stress-induced gastric mucosal epithelial cells damage and its underlying molecular mechanism. The gastric mucosal epithelial cell line GES-1 was treated with 200 μM of H₂O₂ to construct an oxidative stress-induced damage model. The H₂O₂ cells were then administrated with different concentrations of Que. The results indicated that high concentration of Que (100 μM) showed cytotoxicity in H₂O₂-induced GES-1 cells. However, appropriate concentration of Que (25 and 50 μM) alleviated the oxidative stress damage induced by H₂O₂, as demonstrated by the increase of proliferation, decrease of ROS generation, apoptosis, inflammation, and alleviation of mitochondrial function and cell barrier. In addition, Que increased the activation of phosphorylation of PI3K and AKT decreased by H₂O₂. To investigate whether Que alleviated the oxidative stress damage in GES-1 cells by the PI3K/AKT signaling pathway, the GES-1 cells were treated with Que (25 μM) combined with and without LY294002, the PI3K inhibitor. The results showed that LY294002 suppressed the alleviation effect on Que in H₂O₂-induced GES-1 cells. In conclusion, the current study demonstrates that Que alleviates oxidative stress damage in GES-1 cells by improving mitochondrial function and mucosal barrier and suppressing inflammation through regulating the PI3K/AKT signaling pathway, indicating the potential therapeutic effects of Que on FD.

γ-Tocotrienol Protects against Mitochondrial Dysfunction, Energy Deficits, Morphological Damage, and Decreases in Renal Functions after Renal Ischemia

Ischemia-induced mitochondrial dysfunction and ATP depletion in the kidney result in disruption of primary functions and acute injury of the kidney. This study tested whether γ-tocotrienol (GTT), a member of the vitamin E family, protects mitochondrial function, reduces ATP deficits, and improves renal functions and survival after ischemia/reperfusion injury. Vehicle or GTT (200 mg/kg) were administered to mice 12 h before bilateral kidney ischemia, and endpoints were assessed at different timepoints of reperfusion. GTT treatment reduced decreases in state 3 respiration and accelerated recovery of this function after ischemia. GTT prevented decreases in activities of complexes I and III of the respiratory chain, and blocked ischemia-induced decreases in F₀F₁-ATPase activity and ATP content in renal cortical tissue. GTT improved renal morphology at 72 h after ischemia, reduced numbers of necrotic proximal tubular and inflammatory cells, and enhanced tubular regeneration. GTT treatment ameliorated increases in plasma creatinine levels and accelerated recovery of creatinine levels after ischemia. Lastly, 89% of mice receiving GTT and 70% of those receiving vehicle survived ischemia. Conclusions: Our data show novel observations that GTT administration improves mitochondrial respiration, prevents ATP deficits, promotes tubular regeneration, ameliorates decreases in renal functions, and increases survival after acute kidney injury in mice.

Curcumin Alleviates Oxygen-Glucose-Deprivation/Reperfusion-Induced Oxidative Damage by Regulating miR-1287-5p/LONP2 Axis in SH-SY5Y Cells

Oxidative stress-induced neuronal damage is a main cause of ischemia/reperfusion injury. Curcumin (Cur), the principal constituent extracted from dried rhizomes of Curcuma longa L. (turmeric), exhibits excellent antioxidant effects. Previous studies have indicated that miR-1287-5p was downregulated in patients with ischemic stroke. Additionally, we predicted that Lon Peptidase 2, Peroxisomal (LONP2), which is involved in oxidative stress regulation, is targeted by miR-1287-5p. The aim of the current study is to investigate the effect of Cur on ischemia/reperfusion damage and its underlying mechanism. To mimic ischemia/reperfusion damage environment, SH-SY5Y cells were subjected to oxygen-glucose-deprivation/reperfusion (OGD/R). OGD/R treatment downregulated miR-1287-5p and upregulated LONP2 in SH-SY5Y cells, but Cur alleviated OGD/R-induced oxidative damage and reversed the effect of OGD/R on the expression of miR-1287-5p and LONP2. Furthermore, we confirmed the interactive relationship between miR-1287-5p and LONP2 (negative regulation). We revealed that miR-1287-5p overexpression alleviated OGD/R-induced oxidative damage alleviation, similar to the effect of Cur. MiR-1287-5p inhibition accentuated OGD/R-induced oxidative damage in SH-SY5Y cells, which was reversed by Cur. The expression of LONP2 in OGD/R-treated SH-SY5Y cells was decreased by miR-1287-5p overexpression and increased by miR-1287-5p inhibition, and Cur counteracted the increase in LONP2 expression induced by miR-1287-5p inhibition. In conclusion, we suggest that Cur alleviates OGD/R-induced oxidative damage in SH-SY5Y cells by regulating the miR-1287-5p/LONP2 axis. The findings provide a theoretical basis for the clinical application of curcumin.

Quercetin Protects H9c2 Cardiomyocytes against Oxygen-Glucose Deprivation/Reoxygenation-Induced Oxidative Stress and Mitochondrial Apoptosis by Regulating the ERK1/2/DRP1 Signaling Pathway

Reperfusion of blood flow during ischemic myocardium resuscitation induces ischemia/reperfusion (I/R) injury. Oxidative stress has been identified as a major cause in this process. Quercetin (QCT) is a member of the flavonoid family that exerts antioxidant effects. The aim of this study was to investigate the preventive effects of QCT on I/R injury and its underlying mechanism. To this end, H9c2 cardiomyocytes were treated with different concentrations of QCT (10, 20, and 40 μM) and subsequently subjected to oxygen-glucose deprivation/reperfusion (OGD/R) administration. The results indicated that OGD/R-induced oxidative stress, apoptosis, and mitochondrial dysfunction in H9c2 cardiomyocytes were aggravated following 40 μM QCT treatment and alleviated following the administration of 10 and 20 μM QCT prior to OGD/R treatment. In addition, OGD/R treatment inactivated ERK1/2 signaling activation. The effect was mitigated using 10 and 20 μM QCT prior to OGD/R treatment. In conclusion, these results suggested that low concentrations of QCT might alleviate I/R injury by suppressing oxidative stress and improving mitochondrial function through the regulation of ERK1/2-DRP1 signaling, providing a potential candidate for I/R injury prevention.

Tocotrienols and Cancer: From the State of the Art to Promising Novel Patents

BACKGROUND

Tocotrienols (TTs) are vitamin E derivatives naturally occurring in several plants and vegetable oils. Like Tocopherols (TPs), they comprise four isoforms, α, β, γ and δ, but unlike TPs, they present an unsaturated isoprenoid chain. Recent studies indicate that TTs provide important health benefits, including neuroprotective, anti-inflammatory, anti-oxidant, cholesterol lowering and immunomodulatory effects. Moreover, they have been found to possess unique anti-cancer properties.

OBJECTIVE

The purpose of this review is to present an overview of the state of the art of TTs role in cancer prevention and treatment, as well as to describe recent patents proposing new methods for TTs isolation, chemical modification and use in cancer prevention and/or therapy.

METHODS

Recent literature and patents focusing on TTs anti-cancer applications have been identified and reviewed, with special regard to their scientific impact and novelty.

RESULTS

TTs have demonstrated significant anti-cancer activity in multiple tumor types, both in vitro and in vivo. Furthermore, they have shown synergistic effects when given in combination with standard anti-cancer agents or other anti-tumor natural compounds. Finally, new purification processes and transgenic sources have been designed in order to improve TTs production, and novel TTs formulations and synthetic derivatives have been developed to enhance their solubility and bioavailability.

CONCLUSION

The promising anti-cancer effects shown by TTs in several preclinical studies may open new opportunities for therapeutic interventions in different tumors. Thus, clinical trials aimed at confirming TTs chemopreventive and tumor-suppressing activity, particularly in combination with standard therapies, are urgently needed.

The Vitamin E Derivative Gamma Tocotrienol Promotes Anti-Tumor Effects in Acute Myeloid Leukemia Cell Lines

Acute myeloid leukemia (AML) is a blood cancer characterized by the formation of faulty defective myelogenous cells with morphological heterogeneity and cytogenic aberrations leading to a loss of their function. In an attempt to find an effective and safe AML treatment, vitamin E derivatives, including tocopherols were considered as potential anti-tumor compounds. Recently, other isoforms of vitamin E, namely tocotrienols have been proposed as potential potent anti-cancerous agents, displaying promising therapeutic effects in different cancer types. In this study we evaluated the anti-cancerous effects of γ-tocotrienol, on AML cell lines in vitro. For this purpose, AML cell lines incubated with γ-tocotrienol were examined for their viability, cell cycle status, apoptotic cell death, DNA fragmentation, production of reactive oxygen species and expression of proapoptotic proteins. Our results showed that γ-tocotrienol exhibits time and dose-dependent anti-proliferative, pro-apoptotic and antioxidant effects on U937 and KG-1 cell lines, through the upregulation of proteins involved in the intrinsic apoptotic pathway.

Vitamin E and cancer: an update on the emerging role of γ and δ tocotrienols

Despite significant advances in the diagnosis and treatment of cancer, the latter still remains a fatal disease due to the lack of prevention, early diagnosis, and effective drugs. Radiotherapy, chemotherapy, and surgery are not only expensive but produce a number of side effects that are detrimental to the patients' quality of life. Therefore, there is a great need to discover anti-cancer therapies that are specific to cancer cells and affordable, safe, and well tolerated by the patients. Vitamin E is a potential candidate due to its safety. Accumulating evidence on the anti-cancer potency of vitamin E has shifted the focus from tocopherols (TOCs) to tocotrienols (TTs). γ-TT and δ-TT have the highest anti-cancer activities and target common molecular pathways involved in the inhibition of the cell cycle, the induction of apoptosis and autophagy, and the inhibition of invasion, metastasis, and angiogenesis. Future directions should focus on further investigating how γ-TT and δ-TT (solely or in combination) induce anti-cancer molecular pathways when used in the presence of conventional chemotherapeutic drugs. These studies should be carried out in vitro, and promising results and combinations should then be assessed in in vivo experiments and finally in clinical trials. Finally, future research should focus on further evaluating the roles of γ-TT and δ-TT in the chemoprevention of cancer.

γ-Tocotrienol inhibits oxidative phosphorylation and triggers apoptosis by inhibiting mitochondrial complex I subunit NDUFB8 and complex II subunit SDHB

Tocotrienols (T3s) are a subgroup of vitamin E and they have been widely tested to inhibit cell growth in various tumor types. Previous studies have shown that T3s inhibit cancer cell growth by targeting multiple signaling transduction and cellular processes. However, the role of T3s in the regulation of cellular bioenergetic processes remains unclear. In this study, we found that γ-T3 interacts with mitochondrial electron transfer chain NDUFB8 (a subunit of complex I) and SDHB (a subunit of complex II) and inhibits oxidative phosphorylation (OXPHOS), and triggers the production of reactive oxygen species (ROS). In addition, we observed that γ-T3 upregulates the glycolytic capacity in cells, but it did not compensate for cellular ATP generation and decreased the ATP levels in cells. Furthermore, we performed western blots and RT-PCR to measure the mRNA and protein levels of mitochondrial electron transfer chain (ETC) proteins and complex V (ATP synthase), where the results indicated that γ-T3 specifically inhibited the levels of NDUFB8 and SDHB, whereas it had little effect on UQCRC2 (a subunit of complex III), COX4I1 (a subunit of complex IV), and ATP5F1A (a subunit of complex V). The inhibition of NDUFB8 and SDHB by γ-T3 led to the overproduction of ROS and the depletion of ATP, which may be responsible for inducing apoptosis in cancer cells. Our results suggest that mitochondrial respiration may be an effective target for anticancer treatments based on γ-T3.

Tocotrienols Modulate a Life or Death Decision in Cancers

Malignancy often arises from sophisticated defects in the intricate molecular mechanisms of cells, rendering a complicated molecular ground to effectively target cancers. Resistance toward cell death and enhancement of cell survival are the common adaptations in cancer due to its infinite proliferative capacity. Existing cancer treatment strategies that target a single molecular pathway or cancer hallmark fail to fully resolve the problem. Hence, multitargeted anticancer agents that can concurrently target cell death and survival pathways are seen as a promising alternative to treat cancer. Tocotrienols, a minor constituent of the vitamin E family that have previously been reported to induce various cell death mechanisms and target several key survival pathways, could be an effective anticancer agent. This review puts forward the potential application of tocotrienols as an anticancer treatment from a perspective of influencing the life or death decision of cancer cells. The cell death mechanisms elicited by tocotrienols, particularly apoptosis and autophagy, are highlighted. The influences of several cell survival signaling pathways in shaping cancer cell death, particularly NF-κB, PI3K/Akt, MAPK, and Wnt, are also reviewed. This review may stimulate further mechanistic researches and foster clinical applications of tocotrienols via rational drug designs.

The anti-cancer activity and potential clinical application of rice bran extracts and fermentation products

Rice bran is the main by-product of rice processing and contains approximately 64% of the nutrients in rice. Its various nutrient elements include rice bran proteins, oil, oryzanol, vitamins, polysaccharides, etc. The use of fermented technology can increase the content of bioactive peptides, promote the absorption efficiency, and further improve the functionality and added value of rice bran. In recent years, the nutritional value and function of the extracts and fermented products of rice bran have been emphatically studied. Rice bran extracts and fermentation products serve a critical role in the anti-inflammatory reaction, reducing the plasma lipid effect and increasing anti-cancer activity. Moreover, few review studies have been reported on the anti-cancer activity and potential mechanism of action of rice bran extract and its fermentation products. In this review, we focused on the anti-cancer function, mechanisms, and potential clinical usage of rice bran extracts and fermentation products in the adjuvant therapy of cancer patients.

Extracts and fermentation products of rice bran serve important roles in mediating inflammation, cell cycel, cell apotosis, and cancer prevention.

γ-Tocotrienol-Inhibited Cell Proliferation of Human Gastric Cancer by Regulation of Nuclear Factor-κB Activity

γ-Tocotrienol (γ-T3) exhibits the activity of anticancer via regulating cell signaling pathways. Nuclear factor-κB (NF-κB), one of the crucial pro-inflammatory factors, is involved in the regulation of cell proliferation, apoptosis, invasion, and migration of tumor. In the present study, NF-κB activity inhibited by γ-T3 was investigated in gastric cancer cells. Cell proliferation, NF-κB activity, active protein phosphatase type 2A (PP2A), and ataxia-telangiectasia mutated (ATM) protein were explored using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT), methylene blue, enzyme-linked immunosorbent assay (ELISA), malachite green, luciferase, and Western blotting assays. The effects of γ-T3 on tumor growth and the expression of NF-κB and PP2A proteins were also further examined by implanting human gastric cancer cells in a BALB/c nude mouse model. The results showed that γ-T3 significantly inhibited the cell proliferation and attenuated the NF-κB activity in vitro and in vivo. γ-T3 dramatically increased PP2A activity and protein expression, which suppressed ATM phosphorylation and its translocation to the cytoplasm in gastric cancer cells. Thus, our findings may provide mechanistic insight into effects of γ-T3 on the regulation of NF-κB activity by a PP2A-dependent mechanism and suggest that PP2A may serve as a molecular target for a potential chemopreventive agent.

γ-Tocotrienol Inhibits Proliferation and Induces Apoptosis Via the Mitochondrial Pathway in Human Cervical Cancer HeLa Cells

γ-Tocotrienol, a kind of isoprenoid phytochemical, has antitumor activity. However, there is limited evidence that it has an effect on cervical cancer. In this study, the capacity to inhibit proliferation and induce apoptosis in human cervical cancer HeLa cells and the mechanism underlying these effects were examined. The results indicated that a γ-tocotrienol concentration over 30 μM inhibited the growth of HeLa cells with a 50% inhibitory concentration (IC₅₀) of 46.90 ± 3.50 μM at 24 h, and significantly down-regulated the expression of proliferative cell nuclear antigen (PCNA) and Ki-67. DNA flow cytometric analysis indicated that γ-tocotrienol arrested the cell cycle at G0/G1 phase and reduced the S phase in HeLa cells. γ-tocotrienol induced apoptosis of HeLa cells in a time- and dose-dependent manner. γ-tocotrienol-induced apoptosis in HeLa cells was accompanied by down-regulation of Bcl-2, up-regulation of Bax, release of cytochrome from mitochondria, activation of caspase-9 and caspase-3, and subsequent poly (ADP-ribose) polymerase (PARP) cleavage. These results suggested that γ-tocotrienol could significantly inhibit cell proliferation through G0/G1 cell cycle arrest, and induce apoptosis via the mitochondrial apoptotic pathway in human cervical cancer HeLa cells. Thus, our findings revealed that γ-tocotrienol may be considered as a potential agent for cervical cancer therapy.

Heat-stabilised rice bran consumption by colorectal cancer survivors modulates stool metabolite profiles and metabolic networks: a randomised controlled trial

Rice bran (RB) consumption has been shown to reduce colorectal cancer (CRC) growth in mice and modify the human stool microbiome. Changes in host and microbial metabolism induced by RB consumption was hypothesised to modulate the stool metabolite profile in favour of promoting gut health and inhibiting CRC growth. The objective was to integrate gut microbial metabolite profiles and identify metabolic pathway networks for CRC chemoprevention using non-targeted metabolomics. In all, nineteen CRC survivors participated in a parallel randomised controlled dietary intervention trial that included daily consumption of study-provided foods with heat-stabilised RB (30 g/d) or no additional ingredient (control). Stool samples were collected at baseline and 4 weeks and analysed using GC-MS and ultra-performance liquid chromatography-MS. Stool metabolomics revealed 93 significantly different metabolites in individuals consuming RB. A 264-fold increase in β-hydroxyisovaleroylcarnitine and 18-fold increase in β-hydroxyisovalerate exemplified changes in leucine, isoleucine and valine metabolism in the RB group. A total of thirty-nine stool metabolites were significantly different between RB and control groups, including increased hesperidin (28-fold) and narirutin (14-fold). Metabolic pathways impacted in the RB group over time included advanced glycation end products, steroids and bile acids. Fatty acid, leucine/valine and vitamin B₆ metabolic pathways were increased in RB compared with control. There were 453 metabolites identified in the RB food metabolome, thirty-nine of which were identified in stool from RB consumers. RB consumption favourably modulated the stool metabolome of CRC survivors and these findings suggest the need for continued dietary CRC chemoprevention efforts.

Scientific Evidence of Rice By-Products for Cancer Prevention: Chemopreventive Properties of Waste Products from Rice Milling on Carcinogenesis In Vitro and In Vivo

Cancer is a significant global health concern affecting men and women worldwide. Although current chemopreventive drugs could inhibit the growth of cancer cells, they exert many adverse side effects. Dietary factor plays a crucial role in the management of cancers and has drawn the attention of researchers to be used as an option to combat this disease. Both in vitro and in vivo studies showed that rice and its by-products display encouraging results in the prevention of this disease. The mechanism of anticancer effect is suggested partly through potentiation of bioactive compounds like vitamin E, phytic acid, γ-aminobutyric acid (GABA), γ-oryzanol, and phenolics. Nevertheless, the bioactivity of rice and its by-products is still incompletely understood. In this review, we present the findings from a preclinical study both in in vitro and in animal experiments on the promising role of rice by-products with focus on cancer prevention.

Tocotrienol-rich fraction (TRF) suppresses the growth of human colon cancer xenografts in Balb/C nude mice by the Wnt pathway

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.

S-benzyl-cysteine-mediated cell cycle arrest and apoptosis involving activation of mitochondrial-dependent caspase cascade through the p53 pathway in human gastric cancer SGC-7901 cells

S-benzyl-cysteine (SBC) is a structural analog of S-allylcysteine (SAC), which is one of the major water- soluble compounds in aged garlic extract. In this study, anticancer activities and the underlying mechanisms of SBC action were investigated and compared these with those of SAC using human gastric cancer SGC-7901 cells. SBC significantly suppressed the survival rate of SGC-7901 cells in a concentration- and time-dependent manner, and the inhibitory activities of SBC were stronger than those of SAC. Flow cytometry revealed that SBC induced G2-phase arrest and apoptosis in SGC-7901 cells. Typical apoptotic morphological changes were observed by Hoechst 33258 dye assay. SBC-treatment dramatically induced the dissipation of mitochondrial membrane potential (Δψm), and enhanced the enzymatic activities of caspase-9 and caspase-3 whilst hardly affecting caspase-8 activity. Furthermore, Western blotting indicated that SBC-induced apoptosis was accompanied by up-regulation of the expression of p53, Bax and the down-regulation of Bcl-2. Taken together, this study suggested that SBC exerts cytotoxic activity involving activation of mitochondrial-dependent apoptosis through p53 and Bax/Bcl-2 pathways in human gastric cancer SGC-7901 cells.

Exogenous γ-tocotrienol promotes preimplantation development and improves the quality of porcine embryos

γ-tocotrienol (GTT), an isomer of vitamin E, has been the subject of increasing interest due to its strong anti-oxidant effects. Therefore, in this study, the effects of GTT on blastocyst development, expression levels of reactive oxygen species (ROS) and apoptotic index were investigated in preimplantation porcine embryos. After in vitro maturation and fertilisation, porcine embryos were cultured for 6 days in porcine zygote medium 3 supplemented with or without GTT (200 μM) under oxidative stress conditions (200 μM hydrogen peroxide (H2O2)). Blastocyst development was significantly improved in the GTT-treated group when compared with the H2O2-treated group (P < 0.05). Subsequent evaluation of the intracellular levels of ROS and numbers of apoptotic nuclei in GTT-treated blastocysts revealed that ROS levels of GTT-treated porcine blastocysts were decreased (P < 0.05) and the numbers of apoptotic nuclei were reduced by GTT treatment in porcine embryos. Moreover, the total cell numbers of blastocysts were significantly increased in the GTT-treated group relative to the untreated group under H2O2-induced oxidative stress (P < 0.05). The expression levels of apoptosis-related genes (BCL-XL, BAX) in GTT-treated blastocysts were then investigated using real-time reverse transcription polymerase chain reaction. Expression of the anti-apoptotic BCL-XL gene was shown to be increased in the GTT-treated blastocyst group, whereas expression of the pro-apoptotic BAX gene was decreased. Taken together, these results suggest that GTT (200 μM) under H2O2-induced oxidative stress, thereby improving the developmental competence of porcine embryos via modulation of intracellular levels of ROS and the apoptotic index during the preimplantation stage.

Cytotoxicity and apoptotic activities of alpha-, gamma- and delta-tocotrienol isomers on human cancer cells

Background

Tocotrienols, especially the gamma isomer was discovered to possess cytotoxic effects associated with the induction of apoptosis in numerous cancers. Individual tocotrienol isomers are believed to induce dissimilar apoptotic mechanisms in different cancer types. This study was aimed to compare the cytotoxic potency of alpha-, gamma- and delta-tocotrienols, and to explore their resultant apoptotic mechanisms in human lung adenocarcinoma A549 and glioblastoma U87MG cells which are scarcely researched.

Methods

The cytotoxic effects of alpha-, gamma- and delta-tocotrienols in both A549 and U87MG cancer cells were first determined at the cell viability and morphological aspects. DNA damage types were then identified by comet assay and flow cytometric study was carried out to support the incidence of apoptosis. The involvements of caspase-8, Bid, Bax and mitochondrial membrane permeability (MMP) in the execution of apoptosis were further expounded.

Results

All tocotrienols inhibited the growth of A549 and U87MG cancer cells in a concentration- and time-dependent manner. These treated cancer cells demonstrated some hallmarks of apoptotic morphologies, apoptosis was further confirmed by cell accumulation at the pre-G₁ stage. All tocotrienols induced only double strand DNA breaks (DSBs) and no single strand DNA breaks (SSBs) in both treated cancer cells. Activation of caspase-8 leading to increased levels of Bid and Bax as well as cytochrome c release attributed by the disruption of mitochondrial membrane permeability in both A549 and U87MG cells were evident.

Conclusions

This study has shown that delta-tocotrienol, in all experimental approaches, possessed a higher efficacy (shorter induction period) and effectiveness (higher induction rate) in the execution of apoptosis in both A549 and U87MG cancer cells as compared to alpha- and gamma-tocotrienols. Tocotrienols in particular the delta isomer can be an alternative chemotherapeutic agent for treating lung and brain cancers.

Electronic supplementary material

The online version of this article (doi:10.1186/1472-6882-14-469) contains supplementary material, which is available to authorized users.

Vitamin E transporters in cancer therapy

Besides their potent antioxidant activity, vitamin E isoforms demonstrated multiple therapeutic activities among which is their activity against different cancer types, including breast, prostate, and colon cancers. However, the activity of vitamin E isoforms is limited by their low bioavailability following oral administration. In addition to the low solubility, vitamin E isoforms have been established as substrates for several intestinal and hepatic transport proteins. In this review, we present reported anticancer activity of vitamin E family members and the possible utilization of vitamin E and derivatives as chemosensitizers to reverse multidrug resistance when given as part of a delivery system and/or in combination with anticancer therapeutic drugs. Then, the review discusses disposition of vitamin E members and transport proteins that play a role in determining their systemic bioavailability followed by recent advances in vitamin E formulations and delivery strategies.

Antiproliferation and induction of caspase-8-dependent mitochondria-mediated apoptosis by β-tocotrienol in human lung and brain cancer cell lines

The pure vitamin isomer, β-tocotrienol has the least abundance among the other vitamin E isomers that are present in numerous plants. Hence, it is very scarcely studied for its bioactivity. In this study, the antiproliferative effects and primary apoptotic mechanisms of β-tocotrienol on human lung adenocarcinoma A549 and glioblastoma U87MG cells were investigated. It was evidenced that β-tocotrienol had inhibited the growth of both A549 (GI50=1.38±0.334μM) and U87MG (GI50=2.53±0.604μM) cells at rather low concentrations. Cancer cells incubated with β-tocotrienol were also found to exhibit hallmarks of apoptotic morphologies including membrane blebbing, chromatin condensation and formation of apoptotic bodies. The apoptotic properties of β-tocotrienol in both A549 and U87MG cells were the results of its capability to induce significant (P<0.05) double-strand DNA breaks (DSBs) without involving single-strand DNA breaks (SSBs). β-Tocotrienol is said to induce activation of caspase-8 in both A549 and U87MG cells guided by no activation when caspase-8 inhibitor, z-IETD-fmk was added. Besides, disruption on the mitochondrial membrane permeability of the cells in a concentration- and time-dependent manner had occurred. The induction of apoptosis by β-tocotrienol in A549 and U87MG cells was confirmed to involve both the death-receptor mediated and mitochondria-dependent apoptotic pathways. These findings could potentiate the palm oil derived β-tocotrienol to serve as a new anticancer agent for treating human lung and brain cancers.

Inhibition of human MCF-7 breast cancer cells and HT-29 colon cancer cells by rice-produced recombinant human insulin-like growth binding protein-3 (rhIGFBP-3)

Background

Insulin-like growth factor binding protein-3 (IGFBP-3) is a multifunctional molecule which is closely related to cell growth, apoptosis, angiogenesis, metabolism and senescence. It combines with insulin-like growth factor-I (IGF-I) to form a complex (IGF-I/IGFBP-3) that can treat growth hormone insensitivity syndrome (GHIS) and reduce insulin requirement in patients with diabetes. IGFBP-3 alone has been shown to have anti-proliferation effect on numerous cancer cells.

Methodology/Principal Findings

We reported here an expression method to produce functional recombinant human IGFBP-3 (rhIGFBP-3) in transgenic rice grains. Protein sorting sequences, signal peptide and endoplasmic reticulum retention tetrapeptide (KDEL) were included in constructs for enhancing rhIGFBP-3 expression. Western blot analysis showed that only the constructs with signal peptide were successfully expressed in transgenic rice grains. Both rhIGFBP-3 proteins, with or without KDEL sorting sequence inhibited the growth of MCF-7 human breast cancer cells (65.76 ± 1.72% vs 45.00 ± 0.86%, p < 0.05; 50.84 ± 1.97% vs 45.00 ± 0.86%, p < 0.01 respectively) and HT-29 colon cancer cells (65.14 ±3.84% vs 18.01 ± 13.81%, p < 0.05 and 54.7 ± 9.44% vs 18.01 ± 13.81%, p < 0.05 respectively) when compared with wild type rice.

Conclusion/Significance

These findings demonstrated the feasibility of producing biological active rhIGFBP-3 in rice using a transgenic approach, which will definitely encourage more research on the therapeutic use of hIGFBP-3 in future.

Synergistic effect of combined treatment with gamma-tocotrienol and statin on human malignant mesothelioma cells

The present study is the first to demonstrate the synergetic effect of statins (atorvastatin and simvastatin) and gamma-tocotrienol (γ-T3) on human malignant mesothelioma (MM). Statin + γ-T3 combinations induced greater cell growth inhibition more than each single treatment via inhibition of mevalonate pathway, a well-known target of both γ-T3 and statins. γ-T3 was necessary for endoplasmic reticulum stress markers CHOP and GRP78, whereas an intrinsic apoptotic marker, caspase 3 activation was induced only in the presence of statins. Overall, the combination of γ-T3 and statins could be useful for MM therapy and functions in a complementary style.

γ-Tocotrienol induces paraptosis-like cell death in human colon carcinoma SW620 cells. PLoS One. 2013;8:e57779. [PMID: 23469066 PMCID: PMC3585143 DOI: 10.1371/journal.pone.0057779]

Colorectal cancer is one of the most serious illnesses among diagnosed cancer. As a new type of anti-cancer composition from tocotrienol-rich fraction of palm oil, γ-tocotrienol is widely used in anti-cancer research. The objectives of this study were to investigate the effects of γ-tocotrienol on human colon cancer SW620 and HCT-8 cells. We showed that treatment with different concentrations of γ-tocotrienol resulted in a dose dependent inhibition of cell growth. Cell death induced by γ-tocotrienol was mediated by a paraptosis-like cell death in SW620 and HCT-8 cells. Real-time RT-PCR and western blot analyses showed that γ-tocotrienol inhibited the expression level of β-catenin, cyclin D1 and c-jun. These data suggest that a paraptosis-like cell death induced by γ-tocotrienol in SW620 cells is associated with the suppression of the Wnt signaling pathway, which offers a novel tool for treating apoptosis-resistance colon cancer.

Apoptosis initiation of β-ionone in SGC-7901 gastric carcinoma cancer cells via a PI3K-AKT pathway

β-ionone has been shown to hold potent anti-proliferative and apoptosis induction properties in vitro and in vivo. To investigate the effects of β-ionone on apoptosis initiation and its possible mechanisms of action, we qualified cell apoptosis, proteins related to apoptosis and a phosphatidylinositol 3-kinase (PI3K)-AKT pathway in human gastric adenocarcinoma cancer SGC-7901 cells. The results demonstrated that β-ionone-induced apoptosis in a dose-dependent manner in SGC-7901 cells treated with β-ionone (25, 50, 100 and 200 μmol/L) for 24 h. β-ionone was also shown to induce the expression of cleaved-caspase-3 and inhibit bcl-2 expression in SGC-7901 cells in a dose-dependent manner. The significantly decreased levels of p-PI3K and p-AKT expression were observed in SGC-7901 cells after β-ionone treatments in a time- and dose-dependent manner (P < 0.01). Thus, the apoptosis induction in SGC-7901 cells by β-ionone may be regulated through a PI3K-AKT pathway. These results demonstrate a potential mechanism by which β-ionone to induce apoptosis initiation in SGC-7901 cells.

Chemopreventive properties of dietary rice bran: current status and future prospects

Emerging evidence suggests that dietary rice bran may exert beneficial effects against several types of cancer, such as breast, lung, liver, and colorectal cancer. The chemopreventive potential has been related to the bioactive phytochemicals present in the bran portion of the rice such as ferulic acid, tricin, β-sitosterol, γ-oryzanol, tocotrienols/tocopherols, and phytic acid. Studies have shown that the anticancer effects of the rice bran-derived bioactive components are mediated through their ability to induce apoptosis, inhibit cell proliferation, and alter cell cycle progression in malignant cells. Rice bran bioactive components protect against tissue damage through the scavenging of free radicals and the blocking of chronic inflammatory responses. Rice bran phytochemicals have also been shown to activate anticancer immune responses as well as affecting the colonic tumor microenvironment in favor of enhanced colorectal cancer chemoprevention. This is accomplished through the modulation of gut microflora communities and the regulation of carcinogen-metabolizing enzymes. In addition, the low cost of rice production and the accessibility of rice bran make it an appealing candidate for global dietary chemoprevention. Therefore, the establishment of dietary rice bran as a practical food-derived chemopreventive agent has the potential to have a significant impact on cancer prevention for the global population.

Swainsonine activates mitochondria-mediated apoptotic pathway in human lung cancer A549 cells and retards the growth of lung cancer xenografts

Swainsonine (1, 2, 8-trihyroxyindolizidine, SW), a natural alkaloid, has been reported to exhibit anti-cancer activity on several mouse models of human cancer and human cancers in vivo. However, the mechanisms of SW-mediated tumor regression are not clear. In this study, we investigated the effects of SW on several human lung cancer cell lines in vitro. The results showed that SW significantly inhibited these cells growth through induction of apoptosis in different extent in vitro. Further studies showed that SW treatment up-regulated Bax, down-regulated Bcl-2 expression, promoted Bax translocation to mitochondria, activated mitochondria-mediated apoptotic pathway, which in turn caused the release of cytochrome c, the activation of caspase-9 and caspase-3, and the cleavage of poly (ADP-ribose) polymerase (PARP), resulting in A549 cell apoptosis. However, the expression of Fas, Fas ligand (FasL) or caspase-8 activity did not appear significant changes in the process of SW-induced apoptosis. Moreover, SW treatment inhibited Bcl-2 expression, promoted Bax translocation, cytochrome c release and caspase-3 activity in xenograft tumor cells, resulting in a significant decrease of tumor volume and tumor weight in the SW-treated xenograft mice groups in comparison to the control group. Taken together, this study demonstrated for the first time that SW inhibited A549 cancer cells growth through a mitochondria-mediated, caspase-dependent apoptotic pathway in vitro and in vivo.

First evidence that γ-tocotrienol inhibits the growth of human gastric cancer and chemosensitizes it to capecitabine in a xenograft mouse model through the modulation of NF-κB pathway

PURPOSE

Because of poor prognosis and development of resistance against chemotherapeutic drugs, the existing treatment modalities for gastric cancer are ineffective. Hence, novel agents that are safe and effective are urgently needed. Whether γ-tocotrienol can sensitize gastric cancer to capecitabine in vitro and in a xenograft mouse model was investigated.

EXPERIMENTAL DESIGN

The effect of γ-tocotrienol on proliferation of gastric cancer cell lines was examined by mitochondrial dye uptake assay, apoptosis by esterase staining, NF-κB activation by DNA-binding assay, and gene expression by Western blotting. The effect of γ-tocotrienol on the growth and chemosensitization was also examined in subcutaneously implanted tumors in nude mice.

RESULTS

γ-Tocotrienol inhibited the proliferation of various gastric cancer cell lines, potentiated the apoptotic effects of capecitabine, inhibited the constitutive activation of NF-κB, and suppressed the NF-κB-regulated expression of COX-2, cyclin D1, Bcl-2, CXCR4, VEGF, and matrix metalloproteinase-9 (MMP-9). In a xenograft model of human gastric cancer in nude mice, we found that administration of γ-tocotrienol alone (1 mg/kg body weight, intraperitoneally 3 times/wk) significantly suppressed the growth of the tumor and this effect was further enhanced by capecitabine. Both the markers of proliferation index Ki-67 and for microvessel density CD31 were downregulated in tumor tissue by the combination of capecitabine and γ-tocotrienol. As compared with vehicle control, γ-tocotrienol also suppressed the NF-κB activation and the expression of cyclin D1, COX-2, intercellular adhesion molecule-1 (ICAM-1), MMP-9, survivin, Bcl-xL, and XIAP.

CONCLUSIONS

Overall our results show that γ-tocotrienol can potentiate the effects of capecitabine through suppression of NF-κB-regulated markers of proliferation, invasion, angiogenesis, and metastasis.

γ-Tocotrienol is a novel inhibitor of constitutive and inducible STAT3 signalling pathway in human hepatocellular carcinoma: potential role as an antiproliferative, pro-apoptotic and chemosensitizing agent

BACKGROUND AND PURPOSE

Activation of signal transducer and activator of transcription 3 (STAT3) play a critical role in the survival, proliferation, angiogenesis and chemoresistance of tumour cells. Thus, agents that suppress STAT3 phosphorylation have potential as cancer therapies. In the present study, we investigated whether the apoptotic, antiproliferative and chemosensitizing effects of γ-tocotrienol are associated with its ability to suppress STAT3 activation in hepatocellular carcinoma (HCC).

EXPERIMENTAL APPROACH

The effect of γ-tocotrienol on STAT3 activation, associated protein kinases and phosphatase, STAT3-regulated gene products, cellular proliferation and apoptosis in HCC cells was investigated.

KEY RESULTS

γ-Tocotrienol inhibited both the constitutive and inducible activation of STAT3 with minimum effect on STAT5. γ-Tocotrienol also inhibited the activation of Src, JAK1 and JAK2 implicated in STAT3 activation. Pervanadate reversed the γ-tocotrienol-induced down-regulation of STAT3, suggesting the involvement of a protein tyrosine phosphatase. Indeed, we found that γ-tocotrienol induced the expression of the tyrosine phosphatase SHP-1 and deletion of the SHP-1 gene by small interfering RNA abolished the ability of γ-tocotrienol to inhibit STAT3 activation. γ-Tocotrienol also down-regulated the expression of STAT3-regulated gene products, including cyclin D1, Bcl-2, Bcl-xL, survivin, Mcl-1 and vascular endothelial growth factor. Finally, γ-tocotrienol inhibited proliferation, induced apoptosis and significantly potentiated the apoptotic effects of chemotherapeutic drugs (paclitaxel and doxorubicin) used for the treatment of HCC.

CONCLUSIONS AND IMPLICATIONS

Overall, these results suggest that γ-tocotrienol is a novel blocker of the STAT3 activation pathway, with a potential role in future therapies for HCC and other cancers.

γ-Tocotrienol protects against mitochondrial dysfunction and renal cell death

Oxidative stress is a major mechanism of a variety of renal diseases. Tocopherols and tocotrienols are well known antioxidants. This study aimed to determine whether γ-tocotrienol (GT3) protects against mitochondrial dysfunction and renal proximal tubular cell (RPTC) injury caused by oxidants. Primary cultures of RPTCs were injured by using tert-butyl hydroperoxide (TBHP) in the absence and presence of GT3 or α-tocopherol (AT). Reactive oxygen species (ROS) production increased 300% in TBHP-injured RPTCs. State 3 respiration, oligomycin-sensitive respiration, and respiratory control ratio (RCR) decreased 50, 63, and 47%, respectively. The number of RPTCs with polarized mitochondria decreased 54%. F₀F₁-ATPase activity and ATP content decreased 31 and 65%, respectively. Cell lysis increased from 3% in controls to 26 and 52% at 4 and 24 h, respectively, after TBHP exposure. GT3 blocked ROS production, ameliorated decreases in state 3 and oligomycin-sensitive respirations and F₀F₁-ATPase activity, and maintained RCR and mitochondrial membrane potential (ΔΨ(m)) in injured RPTCs. GT3 maintained ATP content, blocked RPTC lysis at 4 h, and reduced it to 13% at 24 h after injury. Treatment with equivalent concentrations of AT did not block ROS production and cell lysis and moderately improved mitochondrial respiration and coupling. This is the first report demonstrating the protective effects of GT3 against RPTC injury by: 1) decreasing production of ROS, 2) improving mitochondrial respiration, coupling, ΔΨ(m), and F₀F₁-ATPase function, 3) maintaining ATP levels, and 4) preventing RPTC lysis. Our data suggest that GT3 is superior to AT in protecting RPTCs against oxidant injury and may prove therapeutically valuable for preventing renal injury associated with oxidative stress.

Role of immunoregulatory transcription factors in differential immunomodulatory effects of tocotrienols

Tocotrienols have been shown to possess antioxidant, antitumor, cardioprotective, and antiproliferative effects. This report describes novel immunomodulatory effects of tocotrienols in murine lymphocytes. γ-Tocotrienol (GT) was more effective in suppressing concanavalin A (Con A)-induced T cell proliferation and cytokine production compared to α-tocotrienol (AT) when present continuously in the culture. GT inhibited T cell activation markers and costimulatory molecule. GT modulated intracellular glutathione in lymphocytes, and the suppressive effects of GT could not be abrogated by thiol or nonthiol antioxidants, indicating a poor link between anti-inflammatory properties of tocotrienols and cellular redox status. It was also observed that GT suppressed Con A-induced activation of NF-κB, AP-1, and NF-κB-dependent gene expression. Cellular uptake studies with tocotrienols showed higher accumulation of GT compared to AT. Similar immunosuppressive effects of GT were also observed when administered to mice. In contrast, transient exposure of lymphocytes to GT (4 h) resulted in higher survival and proliferation of lymphocytes in vitro and in vivo in syngeneic and allogeneic hosts. This was attributed to the ability of GT to induce NF-κB, AP-1, and mTOR activation in lymphocytes upon transient exposure. Our results demonstrated that antioxidants such as tocotrienols may exhibit pleiotropic effects by activating multiple mechanisms in cells.

Tocotrienols fight cancer by targeting multiple cell signaling pathways

Cancer cells are distinguished by several distinct characteristics, such as self-sufficiency in growth signal, resistance to growth inhibition, limitless replicative potential, evasion of apoptosis, sustained angiogenesis, and tissue invasion and metastasis. Tumor cells acquire these properties due to the dysregulation of multiple genes and associated cell signaling pathways, most of which are linked to inflammation. For that reason, rationally designed drugs that target a single gene product are unlikely to be of use in preventing or treating cancer. Moreover, targeted drugs can cause serious and even life-threatening side effects. Therefore, there is an urgent need for safe and effective promiscuous (multitargeted) drugs. "Mother Nature" produces numerous such compounds that regulate multiple cell signaling pathways, are cost effective, exhibit low toxicity, and are readily available. One among these is tocotrienol, a member of the vitamin E family, which has exhibited anticancer properties. This review summarizes data from in vitro and in vivo studies of the effects of tocotrienol on nuclear factor-κB, signal transducer and activator of transcription (STAT) 3, death receptors, apoptosis, nuclear factor (erythroid-derived 2)-like 2 (Nrf2), hypoxia-inducible factor (HIF) 1, growth factor receptor kinases, and angiogenic pathways.

A paraptosis-like cell death induced by δ-tocotrienol in human colon carcinoma SW620 cells is associated with the suppression of the Wnt signaling pathway

Tocotrienol is considered a beneficial effect agent on inhibition of tumor development. In this study, we focused on the effects of δ-tocotrienol and its possible mechanism on induction of death in human colon cancer SW620 cells. δ-Tocotrienol inhibited proliferation of SW620 cell in a dose-dependent manner. Our findings showed that δ-tocotrienol effectively induced paraptosis-like death in SW620 cells, correlated with the vacuolation that may be from welling and fusion of mitochondria and/or the endoplasmic reticulum (ER) as well as caspase-3 nonactivated. However, there were no changes in apoptosis based on flow cytometry analysis. Of being noted, δ-tocotrienol reduced the expression of β-catenin and wnt-1 proteins by about 50% at the highest dose (20μmol/L). δ-Tocotrienol also decreased cyclin D1, c-jun and MMP-7 protein levels in SW620 cells. Altogether, these data indicate that δ-tocotrienol induces paraptosis-like cell death, which is associated with the suppression of the Wnt signaling pathway. Thus, our findings may provide a novel application in treatment of human colon carcinoma.

Gamma-tocotrienol induced apoptosis is associated with unfolded protein response in human breast cancer cells

Gamma-tocotrienol (γ-T3) is a member of the vitamin E family. Tocotrienols (T3s) are powerful antioxidants and possess anticancer, neuroprotective and cholesterol-lowering properties. Tocotrienols inhibit the growth of various cancer cell lines without affecting normal cells. Less is known about the exact mechanisms of action of T3s on cell death and other growth inhibitory pathways. In the present study, we demonstrate that γ-T3 induces apoptosis in MDA-MB 231 and MCF-7 breast cancer cells as evident by PARP cleavage and caspase-7 activation. Gene expression analysis of MCF-7 cells treated with γ-T3 revealed alterations in the expression of multiple genes involved in cell growth and proliferation, cell death, cell cycle, cellular development, cellular movement and gene expression. Further analysis of differentially modulated genes using Ingenuity Pathway Analysis software suggested modulation of canonical signal transduction or metabolic pathways such as NRF-2-mediated oxidative stress response, TGF-β signaling and endoplasmic reticulum (ER) stress response. Analysis of ER-stress-related proteins in MCF-7 and MDA-MB 231 cells treated with γ-T3 demonstrated activation of PERK and pIRE1α pathway to induce ER stress. Activating transcription factor 3 (ATF3) was identified as the most up-regulated gene (16.8-fold) in response to γ-T3. Activating transcription factor 3 knockdown using siRNA suggested an essential role of ATF3 in γ-T3-induced apoptosis. In summary, we demonstrate that γ-T3 modulates ER stress signaling and have identified ATF3 as a molecular target for γ-T3 in breast cancer cells.

γ-Tocotrienol inhibits angiogenesis of human umbilical vein endothelial cell induced by cancer cell

Antiangiogenic therapy mediated by food components is an established strategy for cancer chemoprevention. Growth factors play critical roles in tumor angiogenesis. A conditioned medium containing growth factors from human gastric adenocarcinoma SGC-7901 cell conditioned medium was used as an angiogenic stimulus in this study. The purpose of this study was to evaluate the inhibitory effect and possible mechanism of γ-tocotrienol on tumor angiogenesis. The results showed that γ-tocotrienol (10-40 μmol/L) significantly suppressed proliferation, migration and tube formation of human umbilical vein endothelial cells (HUVECs) induced by SGC-7901 cell conditioned medium in a dose-dependent manner. γ-Tocotrienol (800-1200 μg/egg) also inhibited new blood vessel formation on the growing chick embryo chorioallantoic membrane in a dose-dependent manner. Moreover, the inhibitory effects of γ-tocotrienol on HUVECs were correlated with inducing the apoptosis and arresting cell cycle at the G(0)/G(1) phase at a dose of 40 μmol/L γ-tocotrienol. In addition, γ-tocotrienol inhibited angiogenesis in HUVECs by down-regulation of β-catenin, cyclin D1, CD44, phospho-VEGFR-2 and MMP-9. The antiangiogenic effects of γ-tocotrienol on HUVECs may be attributable to regulation of Wnt signaling by decreasing β-catenin expression. Thus, our results suggest that γ-tocotrienol has a potential chemopreventive agent via antiangiogenesis.

Endoplasmic reticulum stress contributes to vitamin E succinate-induced apoptosis in human gastric cancer SGC-7901 cells

Vitamin E succinate (RRR-alpha-tocopheryl succinate, VES), an efficient inducer of apoptosis, acts as a potent agent for cancer therapy. However, the mechanism by which VES mediates the effects are not yet fully understood. Here we studied the effect of endoplasmic reticulum (ER) stress and unfolded protein response (UPR) on VES-induced apoptosis of SGC-7901 human gastric cancer cells. VES caused cytological changes typical of apoptosis, increased ER dilation and cytosolic Ca(2+) concentration. And endogenous ER stress markers, GRP78 and GRP94 were transcriptionally and translationally altered. In response to VES, induction of CHOP, activation of caspase-4 and JNK were observed. Furthermore, VES also triggered activation of UPR components, including RNA-dependent protein kinase (PKR)-like ER kinase (PERK), activating transcription factor 6 (ATF6), X-box-binding protein 1 (XBP1), and ATF4 in a concentration- and time-dependent manner. Consequently, our results suggest that VES-induced apoptosis is coupled to ER stress and UPR activation in SGC-7901 human gastric cancer cells.

Tocotrienols, the vitamin E of the 21st century: its potential against cancer and other chronic diseases

Initially discovered in 1938 as a "fertility factor," vitamin E now refers to eight different isoforms that belong to two categories, four saturated analogues (α, β, γ, and δ) called tocopherols and four unsaturated analogues referred to as tocotrienols. While the tocopherols have been investigated extensively, little is known about the tocotrienols. Very limited studies suggest that both the molecular and therapeutic targets of the tocotrienols are distinct from those of the tocopherols. For instance, suppression of inflammatory transcription factor NF-κB, which is closely linked to tumorigenesis and inhibition of HMG-CoA reductase, mammalian DNA polymerases and certain protein tyrosine kinases, is unique to the tocotrienols. This review examines in detail the molecular targets of the tocotrienols and their roles in cancer, bone resorption, diabetes, and cardiovascular and neurological diseases at both preclinical and clinical levels. As disappointment with the therapeutic value of the tocopherols grows, the potential of these novel vitamin E analogues awaits further investigation.