Pancreatic Health - TOCOTRIENOL Tocotrienol.org

Human Studies/ Cohort Studies
Article	Study objective/ findings
Pharmacokinetics and safety of vitamin E δ-tocotrienol after single and multiple doses in healthy subjects with measurement of vitamin E metabolites. Mahipal, A., et.al (2016). Cancer Chemother Pharmacol.	Vitamin E delta-tocotrienol (VEDT) has demonstrated chemopreventive and antineoplastic activity in preclinical models. The aim of our study was to determine the safety and pharmacokinetics of VEDT and its metabolites after single- and multiple-dose administrations in healthy subjects. The results suggest that VEDT can be safely consumed by healthy subjects and achieve bioactive levels, supporting the investigation of VEDT for chemoprevention.

Human Studies/ Cohort Studies

Article

Study objective/ findings

Pharmacokinetics and safety of vitamin E δ-tocotrienol after single and multiple doses in healthy subjects with measurement of vitamin E metabolites.

Mahipal, A., et.al (2016). Cancer Chemother Pharmacol.

Vitamin E delta-tocotrienol (VEDT) has demonstrated chemopreventive and antineoplastic activity in preclinical models. The aim of our study was to determine the safety and pharmacokinetics of VEDT and its metabolites after single- and multiple-dose administrations in healthy subjects. The results suggest that VEDT can be safely consumed by healthy subjects and achieve bioactive levels, supporting the investigation of VEDT for chemoprevention.

In- vivo / Animal Studies
Article	Study objective/ findings
Vitamin E δ-Tocotrienol Levels in Tumor and Pancreatic Tissue of Mice after Oral Administration Husain, K., et.al (2009). Pharmacology.	The pharmacokinetics, tumor and pancreatic tissue levels, and toxicity of δ-tocotrienol in mice because of its anti-tumor activity against pancreatic cancer were investigated. Following a single oral administration of δ-tocotrienol at 100 mg/kg, the peak plasma concentration (C_max) was 57 ± 5 μmol/l, the time required to reach peak plasma concentration (T_max) was 2 h and plasma half-life (t_1/2) was 3.5 h. The δ-tocotrienol was cleared from plasma and liver within 24 h, but delayed from the pancreas. When mice were fed δ-tocotrienol for 6 weeks, the concentration in tumor tissue was 41 ± 3.5 nmol/g. This concentration was observed with the oral dose (100 mg/kg) of δ-tocotrienol which inhibited tumor growth by 80% in our previous studies. Interestingly, δ-tocotrienol was 10-fold more concentrated in the pancreas than in the tumor. We observed no toxicity due to δ-tocotrienol as mice gained normal weight with no histopathological changes in tissues. Our data suggest that bioactive levels of δ-tocotrienol can be achieved in the pancreas following oral administration and supports its clinical investigation in pancreatic cancer.

In- vivo / Animal Studies

Article

Study objective/ findings

Vitamin E δ-Tocotrienol Levels in Tumor and Pancreatic Tissue of Mice after Oral Administration

Husain, K., et.al (2009). Pharmacology.

The pharmacokinetics, tumor and pancreatic tissue levels, and toxicity of δ-tocotrienol in mice because of its anti-tumor activity against pancreatic cancer were investigated. Following a single oral administration of δ-tocotrienol at 100 mg/kg, the peak plasma concentration (C_max) was 57 ± 5 μmol/l, the time required to reach peak plasma concentration (T_max) was 2 h and plasma half-life (t_1/2) was 3.5 h. The δ-tocotrienol was cleared from plasma and liver within 24 h, but delayed from the pancreas. When mice were fed δ-tocotrienol for 6 weeks, the concentration in tumor tissue was 41 ± 3.5 nmol/g. This concentration was observed with the oral dose (100 mg/kg) of δ-tocotrienol which inhibited tumor growth by 80% in our previous studies. Interestingly, δ-tocotrienol was 10-fold more concentrated in the pancreas than in the tumor. We observed no toxicity due to δ-tocotrienol as mice gained normal weight with no histopathological changes in tissues. Our data suggest that bioactive levels of δ-tocotrienol can be achieved in the pancreas following oral administration and supports its clinical investigation in pancreatic cancer.

In-vitro Studies
Article	Study objective/ findings
δ-Tocotrienol, a natural form of vitamin E, inhibits pancreatic cancer stem-like cells and prevents pancreatic cancer metastasis. Husain, K., et.al (2017). Oncotarget.	The growth, metastasis, and chemotherapy resistance of pancreatic ductal adenocarcinoma (PDAC) is characterized by the activation and growth of tumor-initiating cells in distant organs that have stem-like properties. Thus, inhibiting growth of these cells may prevent PDAC growth and metastases. We have demonstrated that δ-tocotrienol, a natural form of vitamin E (VEDT), is bioactive against cancer, delays progression, and prevents metastases in transgenic mouse models of PDAC. In this report, we provide the first evidence that VEDT selectively inhibits PDAC stem-like cells. VEDT inhibited the viability, survival, self-renewal, and expression of Oct4 and Sox2 transcription factors in 3 models of PDAC stem-like cells. In addition, VEDT inhibited the migration, invasion, and several biomarkers of epithelial-to-mesenchymal transition and angiogenesis in PDAC cells and tumors. These processes are critical for tumor metastases. Furthermore, in the L3.6pl orthotopic model of PDAC metastases, VEDT significantly inhibited growth and metastases of these cells. Finally, in an orthotopic xenograft model of human PDAC stem-like cells, we showed that VEDT significantly retarded the growth and metastases of gemcitabine-resistant PDAC human stem-like cells. Because VEDT has been shown to be safe and to reach bioactive levels in humans, this work supports investigating VEDT for chemoprevention of PDAC metastases.
Effects of Tocotrienols on Insulin Secretion-Associated Genes Expression of Rat Pancreatic Islets in a Dynamic Culture. Chia, L.L., et.al (2016). Front Pharmacol.	The aim of this study was to determine the effects of δ-T3, γ-T3, and α-T3 on insulin secretion-associated genes expression of rat pancreatic islets in a dynamic culture. Pancreatic islets freshly isolated from male Wistar rats were treated with T3 for 1 h at 37°C in a microfluidic system with continuous operation. The cells were collected for total RNA extraction and reverse-transcribed, followed by measurement of insulin secretion-associated genes expression using quantitative real-time polymerase chain reaction. Molecular docking experiments were performed to gain insights on how the T3 bind to the receptors. Short-term exposure of δ- and γ-T3 to pancreatic β cells in a stimulant glucose condition (16.7 mM) significantly regulated preproinsulin mRNA levels and insulin gene transcription. In contrast, α-T3 possessed less ability in the activation of insulin synthesis level. Essentially, potassium chloride (KCl), a β cell membrane depolarising agent added into the treatment further enhanced the insulin production. δ- and γ-T3 revealed significantly higher quantitative expression in most of the insulin secretion-associated genes groups containing 16.7 mM glucose alone and 16.7 mM glucose with 30 mM KCl ranging from 600 to 1200 μM (p < 0.05). The findings suggest the potential of δ-T3 in regulating insulin synthesis and glucose-stimulated insulin secretion through triggering pathway especially in the presence of KCl.
EGR-1/Bax pathway plays a role in vitamin E δ-tocotrienol-induced apoptosis in pancreatic cancer cells. Wang, C., et.al (2015). J Nutr Biochem.	The anticancer activity of δ-tocotrienol, a bioactive vitamin E present in whole grain cereals, annatto beans and palm fruit, is strongly dependent on its effect on the induction of apoptosis. δ-Tocotrienol-induced apoptosis is associated with consistent induction in the expression of the proapoptotic protein Bcl-2-associated X protein (Bax). The molecular mechanism by which δ-tocotrienol regulates Bax expression is unknown. We carried out a DNA microarray study that identified δ-tocotrienol induction of the zinc finger transcription factor EGR-1 in pancreatic cancer cells. Here, we provide evidence linking δ-tocotrienol-induced apoptosis in pancreatic cancer cells to EGR-1 regulation of Bax expression. Forced expression of EGR-1 induces Bax expression and apoptosis in pancreatic cancer cells. In contrast, knockdown of δ-tocotrienol-induced EGR-1 by small interfering RNA attenuated δ-tocotrienol-induced Bax expression and reduced δ-tocotrienol-induced apoptosis. Further analyses showed that de novo protein synthesis was not required for δ-tocotrienol-induced EGR-1 expression, suggesting a direct effect of δ-tocotrienol on EGR-1 expression. Furthermore, a chromatin immunoprecipitation assay demonstrated that EGR-1 binds to the Bax gene promoter. Finally, δ-tocotrienol treatment induced Bax expression and activated EGR-1 in the pancreatic neoplastic cells of the PDX-Cre Kras genetically engineered model of pancreatic cancer. Our study provides the first evidence for EGR-1 as a direct target of vitamin E δ-tocotrienol, suggesting that EGR-1 may act as a proapoptotic factor in pancreatic cancer cells via induction of Bax.
Cytotoxicity and apoptotic activities of alpha-, gamma- and delta-tocotrienol isomers on human cancer cells Lim, S-W., et.al (2014). BMC Complement Altern Med.	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. 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.
Vitamin E δ-tocotrienol induces p27(Kip1)-dependent cell-cycle arrest in pancreatic cancer cells via an E2F-1-dependent mechanism. Hodul, P.J., et.al (2013). PLoS One.	Vitamin E δ-tocotrienol has been shown to have antitumor activity, but the precise molecular mechanism by which it inhibits the proliferation of cancer cells remains unclear. It is demonstrated that δ-tocotrienol exerted significant cell growth inhibition pancreatic ductal cancer (PDCA) cells without affecting normal human pancreatic ductal epithelial cell growth. It is also shown that δ-tocotrienol-induced growth inhibition occurred concomitantly with G(1) cell-cycle arrest and increased p27(Kip1) nuclear accumulation. This finding is significant considering that loss of nuclear p27(Kip1) expression is a well-established adverse prognostic factor in PDCA. Furthermore, δ-tocotrienol inactivated RAF-MEK-ERK signaling, a pathway known to suppress p27(Kip1) expression. To determine whether p27(Kip1) induction is required for δ-tocotrienol inhibition of PDCA cell proliferation, we stably silenced the CDKN1B gene, encoding p27(Kip1), in MIAPaCa-2 PDCA cells and demonstrated that p27(Kip1) silencing suppressed cell-cycle arrest induced by δ-tocotrienol. Furthermore, δ-tocotrienol induced p27(Kip1) mRNA expression but not its protein degradation. p27(Kip1) gene promoter activity was induced by δ-tocotrienol through the promoter’s E2F-1 binding site, and this activity was attenuated by E2F-1 depletion using E2F-1 small interfering RNA. Finally, decreased proliferation, mediated by Ki67 and p27(Kip1) expression by δ-tocotrienol, was confirmed in vivo in a nude mouse xenograft pancreatic cancer model. The findings reveal a new mechanism, dependent on p27(Kip1) induction, by which δ-tocotrienol can inhibit proliferation in PDCA cells, providing a new rationale for p27(Kip1) as a biomarker for δ-tocotrienol efficacy in pancreatic cancer prevention and therapy.
Vitamin E delta-tocotrienol augments the antitumor activity of gemcitabine and suppresses constitutive NF-kappaβ activation in pancreatic cancer. Husain, K., et.al (2011). Mol Cancer Ther.	The NF-κB transcription factor functions as a crucial regulator of cell survival and chemoresistance in pancreatic cancer. Recent studies suggest that tocotrienols, which are the unsaturated forms of vitamin E, are a promising class of anticancer compounds that inhibit the growth and survival of many cancer cells, including pancreatic cancer. Here, we show that tocotrienols inhibited NF-κB activity and the survival of human pancreatic cancer cells in vitro and in vivo. Importantly, we found the bioactivity of the four natural tocotrienol compounds (α-, β-, δ-, and γ-tocotrienol) to be directly related to their ability to suppress NF-κB activity in vitro and in vivo. The most bioactive tocotrienol for pancreatic cancer, δ-tocotrienol, significantly enhanced the efficacy of gemcitabine to inhibit pancreatic cancer growth and survival in vitro and in vivo. Moreover, we found that δ-tocotrienol augmentation of gemcitabine activity in pancreatic cancer cells and tumors is associated with significant suppression of NF-κB activity and the expression of NF-κB transcriptional targets (Bcl-X(L), X-linked inhibitor of apoptosis, and survivin). Our study represents the first comprehensive preclinical evaluation of the activity of natural vitamin E compounds in pancreatic cancer. Given these results, we are conducting a phase I trial of δ-tocotrienol in patients with pancreatic cancer using pancreatic tumor cell survival and NF-κB signaling components as intermediate biomarkers. Our data also support future clinical investigation of δ-tocotrienol to augment gemcitabine activity in pancreatic cancer.
Tocotrienols inhibit AKT and ERK activaition and suppres pancreatic cancer cell proliferation by suppressing the ErbB2 pathway. Shin-Kang, S., et.al (2011). Free Radic Biol Med.	Tocotrienols are members of the vitamin E family but, unlike tocopherols, possess an unsaturated isoprenoid side chain that confers superior anti-cancer properties. The ability of tocotrienols to selectively inhibit the HMG-CoA reductase pathway through posttranslational degradation and to suppress the activity of transcription factor NF-κB could be the basis for some of these properties. Our studies indicate that γ- and δ-tocotrienols have potent antiproliferative activity in pancreatic cancer cells (Panc-28, MIA PaCa-2, Panc-1, and BxPC-3). Indeed both tocotrienols induced cell death (>50%) by the MTT cell viability assay in all four pancreatic cancer cell lines. We also examined the effects of the tocotrienols on the AKT and the Ras/Raf/MEK/ERK signaling pathways by Western blotting analysis. γ- and δ-tocotrienol treatment of cells reduced the activation of ERK MAP kinase and that of its downstream mediator RSK (ribosomal protein S6 kinase) in addition to suppressing the activation of protein kinase AKT. Suppression of activation of AKT by γ-tocotrienol led to downregulation of p-GSK-3β and upregulation accompanied by nuclear translocation of Foxo3. These effects were mediated by the downregulation of Her2/ErbB2 at the messenger level. Tocotrienols but not tocopherols were able to induce the observed effects. Our results suggest that the tocotrienol isoforms of vitamin E can induce apoptosis in pancreatic cancer cells through the suppression of vital cell survival and proliferative signaling pathways such as those mediated by the PI3-kinase/AKT and ERK/MAP kinases via downregulation of Her2/ErbB2 expression. The molecular components for this mechanism are not completely elucidated and need further investigation.
γ-Tocotrienol Inhibits Pancreatic Tumors and Sensitizes Them to Gemcitabine Treatment by Modulating the Inflammatory Microenvironment Kunnumakkara, A.B., et.al (2010). Cancer Res.	Pancreatic cancers generally respond poorly to chemotherapy, prompting a need to identify agents that could sensitize tumors to treatment. In this study, we investigated the response of human pancreatic cells to gamma-tocotrienol (γ-T3), a novel, unsaturated form of vitamin E found in palm oil and rice bran oil, to determine whether it could potentiate the effects of gemcitabine, a standard of care in clinical treatment of pancreatic cancer. γ-T3 inhibited the in vitro proliferation of pancreatic cancer cell lines with variable p53 status and potentiated gemcitabine-induced apoptosis. These effects correlated with an inhibition of NF-κB activation by γ-T3 and a suppression of key cellular regulators including cyclin D1, c-Myc, COX-2, Bcl-2, cIAP, survivin, VEGF, ICAM-1, and CXCR4. In an orthotopic nude mouse model of human pancreatic cancer, oral administration of γ-T3 inhibited tumor growth and enhanced the antitumor properties of gemcitabine. Immunohistochemical analysis indicated a correlation between tumor growth inhibition and reduced expression of Ki-67, COX-2, MMP-9, NF-κB p65 and VEGF in the tissue. Combination treatment also downregulated NF-κB activity along with the NF-κB-regulated gene products cyclin D1, c-Myc, VEGF, MMP-9, CXCR4. Consistent with an enhancement of tumor apoptosis caspase activation was observed in tumor tissues. Overall, Our findings suggest that γ-T3 can inhibit the growth of human pancreatic tumors and sensitize them to gemcitabine by suppressing of NF-κB-mediated inflammatory pathways linked to tumorigenesis.
d-delta-tocotrienol-mediated suppression of the proliferation of human PANC-1, MIA PaCa-2, and BxPC-3 pancreatic carcinoma cells. Hussein & Mo. (2009). Pancreas.	The rate-limiting activity of the mevalonate pathway, 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, provides intermediates essential for growth. Competitive inhibitors of HMG CoA reductase, such as the statins, and down-regulators of reductase, such as the tocotrienols, suppress tumor growth. We evaluated the impact of d-delta-tocotrienol, the most potent vitamin E isomer, on human MIA PaCa-2 and PANC-1 pancreatic carcinoma cells and BxPC-3 pancreatic ductal adenocarcinoma cells. Suppression of mevalonate pathway activities, be it by modulators of HMG CoA reductase (statins, tocotrienols, and farnesol), farnesyl transferase (farnesyl transferase inhibitors), and/or mevalonate pyrophosphate decarboxylase (phenylacetate) activity, may have a potential in pancreatic cancer chemotherapy.

In-vitro Studies

Article

Study objective/ findings

δ-Tocotrienol, a natural form of vitamin E, inhibits pancreatic cancer stem-like cells and prevents pancreatic cancer metastasis.

Husain, K., et.al (2017). Oncotarget.

The growth, metastasis, and chemotherapy resistance of pancreatic ductal adenocarcinoma (PDAC) is characterized by the activation and growth of tumor-initiating cells in distant organs that have stem-like properties. Thus, inhibiting growth of these cells may prevent PDAC growth and metastases. We have demonstrated that δ-tocotrienol, a natural form of vitamin E (VEDT), is bioactive against cancer, delays progression, and prevents metastases in transgenic mouse models of PDAC. In this report, we provide the first evidence that VEDT selectively inhibits PDAC stem-like cells. VEDT inhibited the viability, survival, self-renewal, and expression of Oct4 and Sox2 transcription factors in 3 models of PDAC stem-like cells. In addition, VEDT inhibited the migration, invasion, and several biomarkers of epithelial-to-mesenchymal transition and angiogenesis in PDAC cells and tumors. These processes are critical for tumor metastases. Furthermore, in the L3.6pl orthotopic model of PDAC metastases, VEDT significantly inhibited growth and metastases of these cells. Finally, in an orthotopic xenograft model of human PDAC stem-like cells, we showed that VEDT significantly retarded the growth and metastases of gemcitabine-resistant PDAC human stem-like cells. Because VEDT has been shown to be safe and to reach bioactive levels in humans, this work supports investigating VEDT for chemoprevention of PDAC metastases.

Effects of Tocotrienols on Insulin Secretion-Associated Genes Expression of Rat Pancreatic Islets in a Dynamic Culture.

Chia, L.L., et.al (2016). Front Pharmacol.

The aim of this study was to determine the effects of δ-T3, γ-T3, and α-T3 on insulin secretion-associated genes expression of rat pancreatic islets in a dynamic culture. Pancreatic islets freshly isolated from male Wistar rats were treated with T3 for 1 h at 37°C in a microfluidic system with continuous operation. The cells were collected for total RNA extraction and reverse-transcribed, followed by measurement of insulin secretion-associated genes expression using quantitative real-time polymerase chain reaction. Molecular docking experiments were performed to gain insights on how the T3 bind to the receptors. Short-term exposure of δ- and γ-T3 to pancreatic β cells in a stimulant glucose condition (16.7 mM) significantly regulated preproinsulin mRNA levels and insulin gene transcription. In contrast, α-T3 possessed less ability in the activation of insulin synthesis level. Essentially, potassium chloride (KCl), a β cell membrane depolarising agent added into the treatment further enhanced the insulin production. δ- and γ-T3 revealed significantly higher quantitative expression in most of the insulin secretion-associated genes groups containing 16.7 mM glucose alone and 16.7 mM glucose with 30 mM KCl ranging from 600 to 1200 μM (p < 0.05). The findings suggest the potential of δ-T3 in regulating insulin synthesis and glucose-stimulated insulin secretion through triggering pathway especially in the presence of KCl.

EGR-1/Bax pathway plays a role in vitamin E δ-tocotrienol-induced apoptosis in pancreatic cancer cells.

Wang, C., et.al (2015). J Nutr Biochem.

The anticancer activity of δ-tocotrienol, a bioactive vitamin E present in whole grain cereals, annatto beans and palm fruit, is strongly dependent on its effect on the induction of apoptosis. δ-Tocotrienol-induced apoptosis is associated with consistent induction in the expression of the proapoptotic protein Bcl-2-associated X protein (Bax). The molecular mechanism by which δ-tocotrienol regulates Bax expression is unknown. We carried out a DNA microarray study that identified δ-tocotrienol induction of the zinc finger transcription factor EGR-1 in pancreatic cancer cells. Here, we provide evidence linking δ-tocotrienol-induced apoptosis in pancreatic cancer cells to EGR-1 regulation of Bax expression. Forced expression of EGR-1 induces Bax expression and apoptosis in pancreatic cancer cells. In contrast, knockdown of δ-tocotrienol-induced EGR-1 by small interfering RNA attenuated δ-tocotrienol-induced Bax expression and reduced δ-tocotrienol-induced apoptosis. Further analyses showed that de novo protein synthesis was not required for δ-tocotrienol-induced EGR-1 expression, suggesting a direct effect of δ-tocotrienol on EGR-1 expression. Furthermore, a chromatin immunoprecipitation assay demonstrated that EGR-1 binds to the Bax gene promoter. Finally, δ-tocotrienol treatment induced Bax expression and activated EGR-1 in the pancreatic neoplastic cells of the PDX-Cre Kras genetically engineered model of pancreatic cancer. Our study provides the first evidence for EGR-1 as a direct target of vitamin E δ-tocotrienol, suggesting that EGR-1 may act as a proapoptotic factor in pancreatic cancer cells via induction of Bax.

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

Lim, S-W., et.al (2014). BMC Complement Altern Med.

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. 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.

Vitamin E δ-tocotrienol induces p27(Kip1)-dependent cell-cycle arrest in pancreatic cancer cells via an E2F-1-dependent mechanism.

Hodul, P.J., et.al (2013). PLoS One.

Vitamin E δ-tocotrienol has been shown to have antitumor activity, but the precise molecular mechanism by which it inhibits the proliferation of cancer cells remains unclear. It is demonstrated that δ-tocotrienol exerted significant cell growth inhibition pancreatic ductal cancer (PDCA) cells without affecting normal human pancreatic ductal epithelial cell growth. It is also shown that δ-tocotrienol-induced growth inhibition occurred concomitantly with G(1) cell-cycle arrest and increased p27(Kip1) nuclear accumulation. This finding is significant considering that loss of nuclear p27(Kip1) expression is a well-established adverse prognostic factor in PDCA. Furthermore, δ-tocotrienol inactivated RAF-MEK-ERK signaling, a pathway known to suppress p27(Kip1) expression. To determine whether p27(Kip1) induction is required for δ-tocotrienol inhibition of PDCA cell proliferation, we stably silenced the CDKN1B gene, encoding p27(Kip1), in MIAPaCa-2 PDCA cells and demonstrated that p27(Kip1) silencing suppressed cell-cycle arrest induced by δ-tocotrienol. Furthermore, δ-tocotrienol induced p27(Kip1) mRNA expression but not its protein degradation. p27(Kip1) gene promoter activity was induced by δ-tocotrienol through the promoter’s E2F-1 binding site, and this activity was attenuated by E2F-1 depletion using E2F-1 small interfering RNA. Finally, decreased proliferation, mediated by Ki67 and p27(Kip1) expression by δ-tocotrienol, was confirmed in vivo in a nude mouse xenograft pancreatic cancer model. The findings reveal a new mechanism, dependent on p27(Kip1) induction, by which δ-tocotrienol can inhibit proliferation in PDCA cells, providing a new rationale for p27(Kip1) as a biomarker for δ-tocotrienol efficacy in pancreatic cancer prevention and therapy.

Vitamin E delta-tocotrienol augments the antitumor activity of gemcitabine and suppresses constitutive NF-kappaβ activation in pancreatic cancer.

Husain, K., et.al (2011). Mol Cancer Ther.

The NF-κB transcription factor functions as a crucial regulator of cell survival and chemoresistance in pancreatic cancer. Recent studies suggest that tocotrienols, which are the unsaturated forms of vitamin E, are a promising class of anticancer compounds that inhibit the growth and survival of many cancer cells, including pancreatic cancer. Here, we show that tocotrienols inhibited NF-κB activity and the survival of human pancreatic cancer cells in vitro and in vivo. Importantly, we found the bioactivity of the four natural tocotrienol compounds (α-, β-, δ-, and γ-tocotrienol) to be directly related to their ability to suppress NF-κB activity in vitro and in vivo. The most bioactive tocotrienol for pancreatic cancer, δ-tocotrienol, significantly enhanced the efficacy of gemcitabine to inhibit pancreatic cancer growth and survival in vitro and in vivo. Moreover, we found that δ-tocotrienol augmentation of gemcitabine activity in pancreatic cancer cells and tumors is associated with significant suppression of NF-κB activity and the expression of NF-κB transcriptional targets (Bcl-X(L), X-linked inhibitor of apoptosis, and survivin). Our study represents the first comprehensive preclinical evaluation of the activity of natural vitamin E compounds in pancreatic cancer. Given these results, we are conducting a phase I trial of δ-tocotrienol in patients with pancreatic cancer using pancreatic tumor cell survival and NF-κB signaling components as intermediate biomarkers. Our data also support future clinical investigation of δ-tocotrienol to augment gemcitabine activity in pancreatic cancer.

Tocotrienols inhibit AKT and ERK activaition and suppres pancreatic cancer cell proliferation by suppressing the ErbB2 pathway.

Shin-Kang, S., et.al (2011). Free Radic Biol Med.

Tocotrienols are members of the vitamin E family but, unlike tocopherols, possess an unsaturated isoprenoid side chain that confers superior anti-cancer properties. The ability of tocotrienols to selectively inhibit the HMG-CoA reductase pathway through posttranslational degradation and to suppress the activity of transcription factor NF-κB could be the basis for some of these properties. Our studies indicate that γ- and δ-tocotrienols have potent antiproliferative activity in pancreatic cancer cells (Panc-28, MIA PaCa-2, Panc-1, and BxPC-3). Indeed both tocotrienols induced cell death (>50%) by the MTT cell viability assay in all four pancreatic cancer cell lines. We also examined the effects of the tocotrienols on the AKT and the Ras/Raf/MEK/ERK signaling pathways by Western blotting analysis. γ- and δ-tocotrienol treatment of cells reduced the activation of ERK MAP kinase and that of its downstream mediator RSK (ribosomal protein S6 kinase) in addition to suppressing the activation of protein kinase AKT. Suppression of activation of AKT by γ-tocotrienol led to downregulation of p-GSK-3β and upregulation accompanied by nuclear translocation of Foxo3. These effects were mediated by the downregulation of Her2/ErbB2 at the messenger level. Tocotrienols but not tocopherols were able to induce the observed effects. Our results suggest that the tocotrienol isoforms of vitamin E can induce apoptosis in pancreatic cancer cells through the suppression of vital cell survival and proliferative signaling pathways such as those mediated by the PI3-kinase/AKT and ERK/MAP kinases via downregulation of Her2/ErbB2 expression. The molecular components for this mechanism are not completely elucidated and need further investigation.

γ-Tocotrienol Inhibits Pancreatic Tumors and Sensitizes Them to Gemcitabine Treatment by Modulating the Inflammatory Microenvironment

Kunnumakkara, A.B., et.al (2010). Cancer Res.

Pancreatic cancers generally respond poorly to chemotherapy, prompting a need to identify agents that could sensitize tumors to treatment. In this study, we investigated the response of human pancreatic cells to gamma-tocotrienol (γ-T3), a novel, unsaturated form of vitamin E found in palm oil and rice bran oil, to determine whether it could potentiate the effects of gemcitabine, a standard of care in clinical treatment of pancreatic cancer. γ-T3 inhibited the in vitro proliferation of pancreatic cancer cell lines with variable p53 status and potentiated gemcitabine-induced apoptosis. These effects correlated with an inhibition of NF-κB activation by γ-T3 and a suppression of key cellular regulators including cyclin D1, c-Myc, COX-2, Bcl-2, cIAP, survivin, VEGF, ICAM-1, and CXCR4. In an orthotopic nude mouse model of human pancreatic cancer, oral administration of γ-T3 inhibited tumor growth and enhanced the antitumor properties of gemcitabine. Immunohistochemical analysis indicated a correlation between tumor growth inhibition and reduced expression of Ki-67, COX-2, MMP-9, NF-κB p65 and VEGF in the tissue. Combination treatment also downregulated NF-κB activity along with the NF-κB-regulated gene products cyclin D1, c-Myc, VEGF, MMP-9, CXCR4. Consistent with an enhancement of tumor apoptosis caspase activation was observed in tumor tissues. Overall, Our findings suggest that γ-T3 can inhibit the growth of human pancreatic tumors and sensitize them to gemcitabine by suppressing of NF-κB-mediated inflammatory pathways linked to tumorigenesis.

d-delta-tocotrienol-mediated suppression of the proliferation of human PANC-1, MIA PaCa-2, and BxPC-3 pancreatic carcinoma cells.

Hussein & Mo. (2009). Pancreas.

The rate-limiting activity of the mevalonate pathway, 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, provides intermediates essential for growth. Competitive inhibitors of HMG CoA reductase, such as the statins, and down-regulators of reductase, such as the tocotrienols, suppress tumor growth. We evaluated the impact of d-delta-tocotrienol, the most potent vitamin E isomer, on human MIA PaCa-2 and PANC-1 pancreatic carcinoma cells and BxPC-3 pancreatic ductal adenocarcinoma cells. Suppression of mevalonate pathway activities, be it by modulators of HMG CoA reductase (statins, tocotrienols, and farnesol), farnesyl transferase (farnesyl transferase inhibitors), and/or mevalonate pyrophosphate decarboxylase (phenylacetate) activity, may have a potential in pancreatic cancer chemotherapy.

Review Article
Article	Study objectives/ findings
Vitamins in Pancreatic Cancer: A Review of Underlying Mechanisms and Future Applications. Davis-Yadley & Malafa. (2015). Adv Nutr.	Although there is increasing evidence that vitamins influence pancreatic adenocarcinoma biology and carcinogenesis, a comprehensive review is lacking. In this study, we performed a PubMed literature search to review the anticancer mechanisms and the preclinical and clinical studies that support the development of the bioactive vitamins A, C, D, E, and K in pancreatic cancer intervention. Preclinical studies have shown promising results for vitamin A in pancreatic cancer prevention, with clinical trials showing intriguing responses in combination with immunotherapy. For vitamin C, preclinical studies have shown slower tumor growth rates and/or increased survival when used alone or in combination with gemcitabine, with clinical trials with this combination revealing decreased primary tumor sizes and improved performance status. Preclinical studies with vitamin D analogues have shown potent antiproliferative effects and repression of migration and invasion of pancreatic cancer cells, with a clinical trial showing increased time to progression when calciferol was added to docetaxel. For vitamin E, preclinical studies have shown that δ-tocotrienol and γ-tocotrienol inhibited tumor cell growth and survival and augmented gemcitabine activity. Early-phase clinical trials with δ-tocotrienol are ongoing. Vitamin K demonstrates activation of apoptosis and inhibition of cellular growth in pancreatic tumor cells; however, there are no clinical studies available for further evaluation. Although preclinical and clinical studies are encouraging, randomized controlled trials with endpoints based on insights gained from mechanistic and preclinical studies and early-phase clinical trials are required to determine the efficacy of bioactive vitamin interventions in pancreatic cancer.

Review Article

Article

Study objectives/ findings

Vitamins in Pancreatic Cancer: A Review of Underlying Mechanisms and Future Applications.

Davis-Yadley & Malafa. (2015). Adv Nutr.

Although there is increasing evidence that vitamins influence pancreatic adenocarcinoma biology and carcinogenesis, a comprehensive review is lacking. In this study, we performed a PubMed literature search to review the anticancer mechanisms and the preclinical and clinical studies that support the development of the bioactive vitamins A, C, D, E, and K in pancreatic cancer intervention. Preclinical studies have shown promising results for vitamin A in pancreatic cancer prevention, with clinical trials showing intriguing responses in combination with immunotherapy. For vitamin C, preclinical studies have shown slower tumor growth rates and/or increased survival when used alone or in combination with gemcitabine, with clinical trials with this combination revealing decreased primary tumor sizes and improved performance status. Preclinical studies with vitamin D analogues have shown potent antiproliferative effects and repression of migration and invasion of pancreatic cancer cells, with a clinical trial showing increased time to progression when calciferol was added to docetaxel. For vitamin E, preclinical studies have shown that δ-tocotrienol and γ-tocotrienol inhibited tumor cell growth and survival and augmented gemcitabine activity. Early-phase clinical trials with δ-tocotrienol are ongoing. Vitamin K demonstrates activation of apoptosis and inhibition of cellular growth in pancreatic tumor cells; however, there are no clinical studies available for further evaluation. Although preclinical and clinical studies are encouraging, randomized controlled trials with endpoints based on insights gained from mechanistic and preclinical studies and early-phase clinical trials are required to determine the efficacy of bioactive vitamin interventions in pancreatic cancer.