A Phase I Safety, Pharmacokinetic, and Pharmacodynamic Presurgical Trial of Vitamin E δ-tocotrienol in Patients with Pancreatic Ductal Neoplasia

Navigating the redox landscape: reactive oxygen species in regulation of cell cycle

Objectives: To advance our knowledge of disease mechanisms and therapeutic options, understanding cell cycle regulation is critical. Recent research has highlighted the importance of reactive oxygen species (ROS) in cell cycle regulation. Although excessive ROS levels can lead to age-related pathologies, ROS also play an essential role in normal cellular functions. Many cell cycle regulatory proteins are affected by their redox status, but the precise mechanisms and conditions under which ROS promote or inhibit cell proliferation are not fully understood.Methods: This review presents data from the scientific literature and publicly available databases on changes in redox state during the cell cycle and their effects on key regulatory proteins.Results: We identified redox-sensitive targets within the cell cycle machinery and analysed different effects of ROS (type, concentration, duration of exposure) on cell cycle phases. For example, moderate levels of ROS can promote cell proliferation by activating signalling pathways involved in cell cycle progression, whereas excessive ROS levels can induce DNA damage and trigger cell cycle arrest or cell death.Discussion: Our findings encourage future research focused on identifying redox-sensitive targets in the cell cycle machinery, potentially leading to new treatments for diseases with dysregulated cell proliferation.

Different Roles of Tocopherols and Tocotrienols in Chemoprevention and Treatment of Prostate Cancer

The vitamin E family contains α-tocopherol (αT), βT, γT, and δT and α-tocotrienol (TE), βTE, γTE, and δTE. Research has revealed distinct roles of these vitamin E forms in prostate cancer (PCa). The ATBC trial showed that αT at a modest dose significantly decreased PCa mortality among heavy smokers. However, other randomized controlled trials including the Selenium and Vitamin E Cancer Prevention Trial (SELECT) indicate that supplementation of high-dose αT (≥400 IU) does not prevent PCa among nonsmokers. Preclinical cell and animal studies also do not support chemopreventive roles of high-dose αT and offer explanations for increased incidence of early-stage PCa reported in the SELECT. In contrast, accumulating animal studies have demonstrated that γT, δT, γTE, and δTE appear to be effective for preventing early-stage PCa from progression to adenocarcinoma in various PCa models. Existing evidence also support therapeutic roles of γTE and its related combinations against advanced PCa. Mechanistic and cell-based studies show that different forms of vitamin E display varied efficacy, that is, δTE ≥ γTE > δT ≥ γT >> αT, in inhibiting cancer hallmarks and enabling characteristics, including uncontrolled cell proliferation, angiogenesis, and inflammation possibly via blocking 5-lipoxygenase, nuclear factor κB, hypoxia-inducible factor-1α, modulating sphingolipids, and targeting PCa stem cells. Overall, existing evidence suggests that modest αT supplement may be beneficial to smokers and γT, δT, γTE, and δTE are promising agents for PCa prevention for modest-risk to relatively high-risk population. Despite encouraging preclinical evidence, clinical research testing γT, δT, γTE, and δTE for PCa prevention is sparse and should be considered.

Radioprotective effectiveness of a novel delta-tocotrienol prodrug on mouse hematopoietic system against 60Co gamma-ray irradiation through inducing granulocyte-colony stimulating factor production

Considering the increasing risk of nuclear attacks worldwide, the development of develop potent and safe radioprotective agents for nuclear emergencies is urgently needed. γ-tocotrienol (GT3) and δ-tocotrienol (DT3) have demonstrated a potent radioprotective effect by inducing the production of granulocyte-colony stimulating factor (G-CSF) in vivo. However, their application is limited because of their low bioavailability. The utilization of ester prodrugs can be an effective strategy for modifying the pharmacokinetic properties of drug molecules. In this study, we initially confirmed that DT3 exhibited the most significant potential for inducing G-CSF effects among eight natural vitamin E homologs. Consequently, we designed and synthesized a series of DT3 ester and ether derivatives, leading to improved radioprotective effects. The metabolic study conducted in vitro and in vivo has identified DT3 succinate 5b as a prodrug of DT3 with an approximately seven-fold higher bioavailability compared to DT3 alone. And DT3 ether derivative 8a were relatively stable and approximately 4 times more bioavailable than DT3 prototype. Furthermore, 5b exhibited superior ability to mitigate radiation-induced pancytopenia, enhance the recovery of bone marrow hematopoietic stem and progenitor cells, and promote splenic extramedullary hematopoiesis in sublethal irradiated mice. Similarly, 8a shown potential radiation protection, but its radiation protection is less than DT3. Based on these findings, we identified 5b as a DT3 prodrug, and providing an attractive candidate for further drug development.

Tocotrienol isoforms: The molecular mechanisms underlying their effects in cancer therapy and their implementation in clinical trials

Tocotrienols are found in a variety of natural sources, like rice bran, annatto seeds and palm oil, and have been shown to have several health-promoting properties, particularly against chronic diseases such as cancer. The incidence of cancer is rapidly increasing around the world, not only a result of continued aging and population growth, but also due to the adoption of aspects of the Western lifestyle, such as high-fat diets and low-physical activity. The literature provides strong evidence that tocotrienols are able to inhibit the growth of various cancers, including breast, lung, ovarian, prostate, liver, brain, colon, myeloma and pancreatic cancers. These findings, along with the reported safety profile of tocotrienols in healthy human volunteers, encourage further research into these compounds' potential use in cancer prevention and treatment. The current review provided detailed information about the molecular mechanisms of action of different tocotrienol isoforms in various cancer models and evaluated the potential therapeutic effects of different vitamin E analogues on important cancer hallmarks, such as cellular proliferation, apoptosis, angiogenesis and metastasis. MEDLINE/PubMed and Scopus databases were used to identify recently published articles that investigated the anticancer effects of vitamin E derivatives in various types of cancer in vitro and in vivo along with clinical evidence of adjuvant chemopreventive benefits. Following an overview of pre-clinical studies, we describe several completed and ongoing clinical trials that are paving the way for the successful implementation of tocotrienols in cancer chemotherapy.

Delta tocotrienol as a supplement to FOLFOXIRI in first-line treatment of metastatic colorectal cancer. A randomized, double-blind, placebo-controlled phase II study

PURPOSE

Triplet chemotherapy might be more effective than doublet chemotherapy in metastatic colorectal cancer (mCRC), but it may also be marked by increased toxicity. To investigate whether δ-tocotrienol, a vitamin E analogue, with possible neuroprotective and anti-inflammatory effects, reduces the toxicity of triplet chemotherapy, we conducted a randomized, double-blind, placebo-controlled trial in mCRC patients receiving first-line 5-fluorouracil, oxaliplatin and irinotecan (FOLFOXIRI).

MATERIAL AND METHODS

Seventy patients with mCRC were randomly assigned (1:1) to receive FOLFOXIRI plus either δ-tocotrienol or placebo at the Department of Oncology, Vejle Hospital, Denmark. Eligibility criteria were adenocarcinoma in the colon or rectum, age 18-75 years and ECOG performance status 0-1. FOLFOXIRI was given in eight cycles followed by four cycles of 5-fluorouracil. δ-tocotrienol 300 mg or placebo × 3 daily was added during chemotherapy and for a maximum of two years. The primary endpoint was time to hospitalization or death during treatment with chemotherapy.

RESULTS

Median time to first hospitalization or death was 3.7 months in the placebo group (95% CI 1.93-not reached (NR)), and was NR in the δ-tocotrienol group (95% CI 1.87-NR) with a hazard ratio of 0.70 (95% CI 0.36-1.36). Grade 3-4 toxicities were uncommon in both groups, except for neutropenia, which occurred in 19 patients (58%) in the placebo group and 17 patients (50%) in the δ-tocotrienol group. There were no grade 3 or 4 peripheral sensory neuropathy. In the placebo group, 24 patients (71%) had oxaliplatin dose reductions compared to 17 patients (47%) in the δ-tocotrienol group (p = 0.047).

CONCLUSION

The addition of δ-tocotrienol to FOLFOXIRI did not statistically significant prolong the time to first hospitalization or death compared to FOLFOXIRI plus placebo. Toxicity was manageable and not statistically different. There was a statistically significant difference in dose reductions of oxaliplatin pointing to a possible neuroprotective effect of δ-tocotrienol.

Vitamin E in the management of pancreatic cancer: A scoping review

Pancreatic cancer is the leading cause of cancer mortality worldwide. Research investigating effective management strategies for pancreatic cancer is ongoing. Vitamin E, consisting of both tocopherol and tocotrienol, has demonstrated debatable effects on pancreatic cancer cells. Therefore, this scoping review aims to summarize the effects of vitamin E on pancreatic cancer. In October 2022, a literature search was conducted using PubMed and Scopus since their inception. Original studies on the effects of vitamin E on pancreatic cancer, including cell cultures, animal models and human clinical trials, were considered for this review. The literature search found 75 articles on this topic, but only 24 articles met the inclusion criteria. The available evidence showed that vitamin E modulated proliferation, cell death, angiogenesis, metastasis and inflammation in pancreatic cancer cells. However, the safety and bioavailability concerns remain to be answered with more extensive preclinical and clinical studies. More in-depth analysis is necessary to investigate further the role of vitamin E in the management of pancreatic cancers.

Phase II trial of delta-tocotrienol in neoadjuvant breast cancer with evaluation of treatment response using ctDNA

Neoadjuvant treatment of breast cancer is applied to an increasing extent, but treatment response varies and side effects pose a challenge. The vitamin E isoform delta-tocotrienol might enhance the efficacy of chemotherapy and reduce the risk of side effects. The aim of this study was to investigate the clinical effect of delta-tocotrienol combined with standard neoadjuvant treatment and the possible association between detectable circulating tumor DNA (ctDNA) during and after neoadjuvant treatment with pathological treatment response. This open-label, randomized phase II trial included 80 women with newly diagnosed, histologically verified breast cancer randomized to standard neoadjuvant treatment alone or in combination with delta-tocotrienol. There was no difference in the response rate or frequency of serious adverse events between the two arms. We developed a multiplex digital droplet polymerase chain reaction (ddPCR) assay for the detection of ctDNA in breast cancer patients that targets a combination of two methylations specific for breast tissue (LMX1B and ZNF296) and one cancer specific methylation (HOXA9). The sensitivity of the assay increased when the cancer specific marker was combined with the ones specific to breast tissue (p < 0.001). The results did not show any association between ctDNA status and pathological treatment response, neither at midterm nor before surgery.

Beneficial and adverse effects of vitamin E on the kidney

This article reviews the beneficial and adverse effects of high-dose vitamin E supplementation on the vitamin E status and renal function in human and rodent studies. The high doses of vitamin E, which can cause renal effects, were compared to upper limits of toxicity (UL) as established by various authorities worldwide. In recent mice studies with higher doses of vitamin E, several biomarkers of tissue toxicity and inflammation were found to be significantly elevated. In these biomarker studies, the severity of inflammation and the increased levels of the biomarkers are discussed together with the need to re-evaluate ULs, given the toxic effects of vitamin E on the kidney and emphasizing oxidative stress and inflammation. The controversy in the literature about vitamin E effects on the kidney is mainly caused by the dose-effects relations that do not give a clear view, neither in human nor animals studies. In addition, more recent studies on rodents with new biomarkers of oxidative stress and inflammation give new insights into possible mechanisms. In this review, the controversy is shown and an advice given on the vitamin E supplementation for renal health.

Clinical and Molecular Attributes and Evaluation of Pancreatic Cystic Neoplasm

Intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs) are all considered "Pancreatic cystic neoplasms (PCNs)" and show a varying risk of developing into pancreatic ductal adenocarcinoma (PDAC). These lesions display different molecular characteristics, mutations, and clinical manifestations. A lack of detailed understanding of PCN subtype characteristics and their molecular mechanisms limits the development of efficient diagnostic tools and therapeutic strategies for these lesions. Proper in vivo mouse models that mimic human PCNs are also needed to study the molecular mechanisms and for therapeutic testing. A comprehensive understanding of the current status of PCN biology, mechanisms, current diagnostic methods, and therapies will help in the early detection and proper management of patients with these lesions and PDAC. This review aims to describe all these aspects of PCNs, specifically IPMNs, by describing the future perspectives.

Effect of vitamins C and E on cancer survival; a systematic review

PURPOSE

Association between vitamins C (VC)/ E (VE) and cancer survival is inconsistent. This systematic review is aimed to summarize trials for effects of VC/VE on cancer survival.

METHODS

Relevant English trials were retrieved from PubMed, Cochrane Library, Embase, Web of Science, Scopus databases, and Clinicaltrials.gov through 21/June/2022. Inclusion criteria were all trials which assessed sole/combinations intake of VC/VE on survival rate, mortality, or remission of any cancer. Exclusion criteria were observational and animal studies.

RESULTS

We reached 30 trials conducted on 38,936 patients with various cancers. Due to severe methodological heterogeneity, meta-analysis was impossible. High dose VC + chemotherapy or radiation was safe with an overall survival (OS) 182 days - 21.5 months. Sole oral or intravenous high dose VC was safe with non-significant change in OS (2.9-8.2 months). VE plus chemotherapy was safe, resulted in stabling diseases for 5 years in 70- 86.7% of patients and OS 109 months. It was found 60% and 16% non-significant reductions in adjusted hazard ratio (HR) deaths or recurrence by 200 mg/d tocotrienol + tamoxifen in breast cancer, respectively. Sole intake of 200-3200 mg/d tocotrienol before resectable pancreatic cancer was safe and significantly increased cancer cells' apoptosis. Combination VC and VE was non-significantly reduced 7% in rate of neoplastic gastric polyp.

CONCLUSION

Although our study is supported improvement of survival and progression rates of cancers by VC/VE, more high quality trials with large sample sizes are required to confirm.

PROSPERO REGISTRATION NUMBER

CRD42020152795.

Fat-Soluble Vitamin Deficiencies and Disruption of the Immune System in Pancreatic Cancer: A Vicious Cycle

ABSTRACT

Pancreatic ductal adenocarcinoma (PDAC) is currently an increasing contributor to cancer-related mortality. Despite advances in cancer treatment, PDAC survival rates have remained roughly unchanged over the years. Specifically, late diagnosis and insensitivity to currently available therapeutic regimens have been identified as the main causes for its poor survival. Pancreatic exocrine insufficiency (PEI) is a typical complication associated with PDAC diagnosis and pancreatic surgery. Pancreatic exocrine insufficiency, a major contributor to maldigestion in PDAC, is often not treated because it remains undetected because of lack of overt signs and symptoms. In this review, we will focus on the major consequences of PEI, including the inadequacy of lipase excretion, which results in deficiency of fat-soluble vitamins. Because PDAC is known for its immune-high jacking mechanisms, we describe key features in which deficiencies of fat-soluble vitamins may contribute to the aggressive biological behavior and immune evasion in PDAC. Because PEI has been shown to worsen survival rates in patients with PDAC, detecting PEI and the related fat-soluble vitamin deficits at the time of PDAC diagnosis is critical. Moreover, timely supplementation of pancreatic enzymes and fat-soluble vitamins may improve outcomes for PDAC patients.

Revisiting the therapeutic potential of tocotrienol

The therapeutic potential of the tocotrienol group stems from its nutraceutical properties as a dietary supplement. It is largely considered to be safe when consumed at low doses for attenuating pathophysiology as shown by animal models, in vitro assays, and ongoing human trials. Medical researchers and the allied sciences have experimented with tocotrienols for many decades, but its therapeutic potential was limited to adjuvant or concurrent treatment regimens. Recent studies have focused on targeted drug delivery by enhancing the bioavailability through carriers, self-sustained emulsions, nanoparticles, and ethosomes. Epigenetic modulation and computer remodeling are other means that will help increase chemosensitivity. This review will focus on the systemic intracellular anti-cancer, antioxidant, and anti-inflammatory mechanisms that are stimulated and/or regulated by tocotrienols while highlighting its potent therapeutic properties in a diverse group of clinical diseases.

Impacts of nutritive and bioactive compounds on cancer development and therapy

For persons who survive with progressive cancer, nutritional therapy and exercise may be significant factors to improve the health condition and life quality of cancer patients. Nutritional therapy and medications are essential to managing progressive cancer. Cancer survivors, as well as cancer patients, are mostly extremely encouraged to search for knowledge about the selection of diet, exercise, and dietary supplements to recover as well as maintain their treatment consequences, living quality, and survival of patients. A healthy diet plays an important role in cancer treatment. Different articles are studied to collect information and knowledge about the use of nutrients in cancer treatment as well as cancer prevention. The report deliberates nutrition and exercise strategies during the range of cancer care, emphasizing significant concerns during treatment of cancer and for patients of advanced cancer, but concentrating mostly on the requirements of the population of persons who are healthy or who have constant disease following their repossession from management. It also deliberates choice nutrition and exercise problems such as dietary supplements, food care, food selections, and weight; problems interrelated to designated cancer sites, and common questions about diet, and cancer survival. Decrease the side effects of medicines both during and after treatment.

Potential “Therapeutic” Effects of Tocotrienol-Rich Fraction (TRF) and Carotene “Against” Bleomycin-Induced Pulmonary Fibrosis in Rats via TGF-β/Smad, PI3K/Akt/mTOR and NF-κB Signaling Pathways

Background: Pulmonary fibrosis (PF) is a chronic, progressive, and, ultimately, terminal interstitial disease caused by a variety of factors, ranging from genetics, bacterial, and viral infections, to drugs and other influences. Varying degrees of PF and its rapid progress have been widely reported in post-COVID-19 patients and there is consequently an urgent need to develop an appropriate, cost-effective approach for the prevention and management of PF. Aim: The potential “therapeutic” effect of the tocotrienol-rich fraction (TRF) and carotene against bleomycin (BLM)-induced lung fibrosis was investigated in rats via the modulation of TGF-β/Smad, PI3K/Akt/mTOR, and NF-κB signaling pathways. Design/Methods: Lung fibrosis was induced in Sprague-Dawley rats by a single intratracheal BLM (5 mg/kg) injection. These rats were subsequently treated with TRF (50, 100, and 200 mg/kg body wt/day), carotene (10 mg/kg body wt/day), or a combination of TRF (200 mg/kg body wt/day) and carotene (10 mg/kg body wt/day) for 28 days by gavage administration. A group of normal rats was provided with saline as a substitute for BLM as the control. Lung function and biochemical, histopathological, and molecular alterations were studied in the lung tissues. Results: Both the TRF and carotene treatments were found to significantly restore the BLM-induced alterations in anti-inflammatory and antioxidant functions. The treatments appeared to show pneumoprotective effects through the upregulation of antioxidant status, downregulation of MMP-7 and inflammatory cytokine expressions, and reduction in collagen accumulation (hydroxyproline). We demonstrated that TRF and carotene ameliorate BLM-induced lung injuries through the inhibition of apoptosis, the induction of TGF-β1/Smad, PI3K/Akt/mTOR, and NF-κB signaling pathways. Furthermore, the increased expression levels were shown to be significantly and dose-dependently downregulated by TRF (50, 100, and 200 mg/kg body wt/day) treatment in high probability. The histopathological findings further confirmed that the TRF and carotene treatments had significantly attenuated the BLM-induced lung injury in rats. Conclusion: The results of this study clearly indicate the ability of TRF and carotene to restore the antioxidant system and to inhibit proinflammatory cytokines. These findings, thus, revealed the potential of TRF and carotene as preventive candidates for the treatment of PF in the future.

The multifaceted roles of mitochondria at the crossroads of cell life and death in cancer

Mitochondria are the cytoplasmic organelles mostly known as the "electric engine" of the cells; however, they also play pivotal roles in different biological processes, such as cell growth/apoptosis, Ca²⁺ and redox homeostasis, and cell stemness. In cancer cells, mitochondria undergo peculiar functional and structural dynamics involved in the survival/death fate of the cell. Cancer cells use glycolysis to support macromolecular biosynthesis and energy production ("Warburg effect"); however, mitochondrial OXPHOS has been shown to be still active during carcinogenesis and even exacerbated in drug-resistant and stem cancer cells. This metabolic rewiring is associated with mutations in genes encoding mitochondrial metabolic enzymes ("oncometabolites"), alterations of ROS production and redox biology, and a fine-tuned balance between anti-/proapoptotic proteins. In cancer cells, mitochondria also experience dynamic alterations from the structural point of view undergoing coordinated cycles of biogenesis, fusion/fission and mitophagy, and physically communicating with the endoplasmic reticulum (ER), through the Ca²⁺ flux, at the MAM (mitochondria-associated membranes) levels. This review addresses the peculiar mitochondrial metabolic and structural dynamics occurring in cancer cells and their role in coordinating the balance between cell survival and death. The role of mitochondrial dynamics as effective biomarkers of tumor progression and promising targets for anticancer strategies is also discussed.

δ-Tocotrienol sensitizes and re-sensitizes ovarian cancer cells to cisplatin via induction of G1 phase cell cycle arrest and ROS/MAPK-mediated apoptosis

OBJECTIVES

Among gynaecologic malignancies, ovarian cancer (OC) represents the leading cause of death for women worldwide. Current OC treatment involves cytoreductive surgery followed by platinum-based chemotherapy, which is associated with severe side effects and development of drug resistance. Therefore, new therapeutic strategies are urgently needed. Herein, we evaluated the anti-tumour effects of Vitamin E-derived δ-tocotrienol (δ-TT) in two human OC cell lines, IGROV-1 and SKOV-3 cells.

MATERIALS AND METHODS

MTT and Trypan blue exclusion assays were used to assess δ-TT cytotoxicity, alone or in combination with other molecules. δ-TT effects on cell cycle, apoptosis, ROS generation and MAPK phosphorylation were investigated by flow cytometry, Western blot and immunofluorescence analyses. The synergism between δ-TT and chemotherapy was evaluated by isobologram analysis.

RESULTS

We demonstrated that δ-TT could induce cell cycle block at G1-S phase and mitochondrial apoptosis in OC cell lines. In particular, we found that the proapoptotic activity of δ-TT correlated with mitochondrial ROS production and subsequent JNK and p38 activation. Finally, we observed that the compound was able to synergize with cisplatin, not only enhancing its cytotoxicity in IGROV-1 and SKOV-3 cells but also re-sensitizing IGROV-1/Pt1 cell line to its anti-tumour effects.

CONCLUSIONS

δ-TT triggers G1 phase cell cycle arrest and ROS/MAPK-mediated apoptosis in OC cells and sensitizes them to platinum treatment, thus representing an interesting option for novel chemopreventive/therapeutic strategies for OC.

Systematic Review of the Integrative Medicine Recommendations for Patients with Pancreatic Cancer

Introduction: Integrative medicine (IM) is a relatively new field where non-traditional therapies with peer-reviewed evidence are incorporated or integrated with more traditional approaches. Methods: A systematic review of the literature from the last 10 years was done by searching clinical trials and randomized-controlled trials on Pubmed that discuss nutrition, supplementation, and lifestyle changes associated with “Pancreatic Cancer.” Results: Only 50 articles ultimately met the inclusion criteria for this review. A total of 15 articles discussed the role of obesity and 10 discussed the influence of stress in increasing the risk of pancreatic cancer. Six discussed the potential beneficial role of Vitamins, 5 of cannabinoids, 4 an anti-inflammatory diet, 3 of nut consumption, 2 of green tea consumption, 2 of curcumin supplementation, 1 role of melatonin, and 1 of probiotics. One article each was found on the theoretical benefits of adhering to either a Mediterranean or ketogenic diet. Discussion: As more surgeons become interested in IM, it is hoped that more diseases where the curative treatment is mainly surgical can benefit from the all-encompassing principles of IM in an effort to improve quality of life and survival in patients with pancreatic cancer.

Utilization of redox modulating small molecules that selectively act as pro-oxidants in cancer cells to open a therapeutic window for improving cancer therapy

There is a rapidly growing body of literature supporting the notion that differential oxidative metabolism in cancer versus normal cells represents a metabolic frailty that can be exploited to open a therapeutic window into cancer therapy. These cancer cell-specific metabolic frailties may be amenable to manipulation with non-toxic small molecule redox active compounds traditionally thought to be antioxidants. In this review we describe the potential mechanisms and clinical applicability in cancer therapy of four small molecule redox active agents: melatonin, vitamin E, selenium, and vitamin C. Each has shown the potential to have pro-oxidant effects in cancer cells while retaining antioxidant activity in normal cells. This dichotomy can be exploited to improve responses to radiation and chemotherapy by opening a therapeutic window based on a testable biochemical rationale amenable to confirmation with biomarker studies during clinical trials. Thus, the unique pro-oxidant/antioxidant properties of melatonin, vitamin E, selenium, and vitamin C have the potential to act as effective adjuvants to traditional cancer therapies, thereby improving cancer patient outcomes.

Beneficial Diets and Pancreatic Cancer: Molecular Mechanisms and Clinical Practice

Pancreatic cancer (PC) is a malignant tumor with high invasiveness, easy metastatic ability, and chemoresistance. Patients with PC have an extremely low survival rate due to the difficulty in early diagnosis. It is estimated that nearly 90% of PC cases are caused by environmental risk factors. Approximately 50% of PC cases are induced by an unhealthy diet, which can be avoided. Given this large attribution to diet, numerous studies have assessed the relationship between various dietary factors and PC. This article reviews three beneficial diets: a ketogenic diet (KD), a Mediterranean diet (MD), and a low-sugar diet. Their composition and impact mechanism are summarized and discussed. The associations between these three diets and PC were analyzed, and we aimed to provide more help and new insights for the prevention and treatment of PC.

Vitamin E beyond Its Antioxidant Label

Vitamin E, comprising tocopherols and tocotrienols, is mainly known as an antioxidant. The aim of this review is to summarize the molecular mechanisms and signaling pathways linked to inflammation and malignancy modulated by its vitamers. Preclinical reports highlighted a myriad of cellular effects like modulating the synthesis of pro-inflammatory molecules and oxidative stress response, inhibiting the NF-κB pathway, regulating cell cycle, and apoptosis. Furthermore, animal-based models have shown that these molecules affect the activity of various enzymes and signaling pathways, such as MAPK, PI3K/Akt/mTOR, JAK/STAT, and NF-κB, acting as the underlying mechanisms of their reported anti-inflammatory, neuroprotective, and anti-cancer effects. In clinical settings, not all of these were proven, with reports varying considerably. Nonetheless, vitamin E was shown to improve redox and inflammatory status in healthy, diabetic, and metabolic syndrome subjects. The anti-cancer effects were inconsistent, with both pro- and anti-malignant being reported. Regarding its neuroprotective properties, several studies have shown protective effects suggesting vitamin E as a potential prevention and therapeutic (as adjuvant) tool. However, source and dosage greatly influence the observed effects, with bioavailability seemingly a key factor in obtaining the preferred outcome. We conclude that this group of molecules presents exciting potential for the prevention and treatment of diseases with an inflammatory, redox, or malignant component.

Co-encapsulation of gemcitabine and tocotrienols in nanovesicles enhanced efficacy in pancreatic cancer

Aim: To synthesize niosomes co-encapsulating gemcitabine (GEM) and tocotrienols, and physicochemically characterize and evaluate the antipancreatic effects of the nanoformulation on Panc 10.05, SW 1990, AsPC-1 and BxPC-3 cells. Materials & methods: Niosomes-entrapping GEM and tocotrienols composed of Span 60, cholesterol and D-α-tocopheryl polyethylene glycol 1000 succinate were produced by Handjani-Vila and film hydration methods. Results: The film hydration produced vesicles measuring 161.9 ± 0.5 nm, approximately 50% smaller in size than Handjani-Vila method, with maximum entrapment efficiencies of 20.07 ± 0.22% for GEM and 34.52 ± 0.10% for tocotrienols. In Panc 10.05 cells, GEM's antiproliferative effect was enhanced 2.78-fold in combination with tocotrienols. Niosomes produced a significant ninefold enhancement in cytotoxicity of the combination, supported by significantly higher cellular uptake of GEM in the cells. Conclusion: This study is a proof of concept on the synthesis of dual-drug niosomes and their efficacy on pancreatic cancer cells in vitro.

The Role of Vitamin E in Breast Cancer Treatment and Prevention: Current Perspectives

Background:

Regarding the multifactorial etiology of breast cancer, food choices, as well as dietary intake, are the main modified factors in cancer prevention. In this sense, understanding molecular pathways involved in breast cancer proliferation can help determine the mechanisms of action of organic compounds such as antioxidant vitamins that are known to protect against cancer.

Objective:

Assess the mechanism of action of vitamin E in breast cancer modulation, with emphasis on important markers of tumor development.

Methods:

It is a systematic review carried out in PubMed and Web of Science databases, from the last 5 years, in Portuguese, English and Spanish. The following terms were selected according to The Medical Subject Headings (MeSH): “breast cancer” OR “breast neoplasms”, “tocopherol” OR “tocotrienols” OR “vitamin E”, as equated terms.

Results:

A total of 595 articles were found and 25 were selected according to inclusion criteria. Vitamin E has been related to suppression/overexpression of important tumorigenic pathways, mainly associated with proliferation, energy metabolism, chemosensitivity and invasion/metastasis. Clinical studies of vitamin E supplementation are needed to assess the dose/response effect on breast cancer patients.

Conclusion:

The safety of vitamin E supplementation is still controversial due to current studies design available. However, when vitamin E is supplemented, the dose and therapeutic regimen must be carefully decided, including the route of administration and breast cancer subtypes to enhance desired effects and minimize unwanted side effects.

Pancreatic Cancer (PDAC): Introduction of Evidence-Based Complementary Measures into Integrative Clinical Management

The most common form of pancreatic cancer is pancreatic ductal adenocarcinoma (PDAC), which comprises some 85% of all cases. Currently, this is the fourth highest cause of cancer mortality worldwide and its incidence is rising steeply. Commonly applied clinical therapies offer limited chance of a lasting cure and the five-year survival rate is one of the lowest of the commonly occurring cancers. This review cultivates the hypothesis that the best management of PDAC would be possible by integrating 'western' clinical medicine with evidence-based complementary measures. Protecting the liver, where PDAC frequently first spreads, is also given some consideration. Overall, the complementary measures are divided into three groups: dietary factors, nutraceutical agents and lifestyle. In turn, dietary factors are considered as general conditioners, multi-factorial foodstuffs and specific compounds. The general conditioners are alkalinity, low-glycemic index and low-cholesterol. The multi-factorial foodstuffs comprise red meat, fish, fruit/vegetables, dairy, honey and coffee. The available evidence for the beneficial effects of the specific dietary and nutraceutical agents was considered at four levels (in order of prominence): clinical trials, meta-analyses, in vivo tests and in vitro studies. Thus, 9 specific agents were identified (6 dietary and 3 nutraceutical) as acceptable for integration with gemcitabine chemotherapy, the first-line treatment for pancreatic cancer. The specific dietary agents were the following: Vitamins A, C, D and E, genistein and curcumin. As nutraceutical compounds, propolis, triptolide and cannabidiol were accepted. The 9 complementary agents were sub-grouped into two with reference to the main 'hallmarks of cancer'. Lifestyle factors covered obesity, diabetes, smoking, alcohol and exercise. An integrative treatment regimen was devised for the management of PDAC patients. This involved combining first-line gemcitabine chemotherapy with the two sub-groups of complementary agents alternately in weekly cycles. The review concludes that integrated management currently offers the best patient outcome. Opportunities to be investigated in the future include emerging modalities, precision medicine, the nerve input to tumors and, importantly, clinical trials.

Safety of dietary supplements use among patients with cancer: A systematic review

Dietary supplements (DS) are commonly taken by patients with cancer, but safety of DS use remains unclear. A systematic literature search was conducted using PubMed, ClinicalTrials.gov, International Pharmaceutical Abstracts and Alt HealthWatch databases from inception through October 12, 2018. Included studies were limited to clinical trials including patients with cancer, DS products as interventions, evaluation of safety endpoints of DS use, and published in English. Sixty-five studies were included to evaluate 20 different DS among patients with 12 types of cancer. Botanical DS (n = 13), vitamins (n = 8), and probiotics/synbiotics (n = 7) were the top 3 types of DS evaluated in these trials. Majority of studied DS appeared safe. Among 19 trials including patients with cancer undergoing chemotherapy, most (n = 18) of studied DS (e.g., vitamins, botanical, omega-3 fatty acid) were found to be safe. Evaluation of DS use and its safety should be regularly incorporated in clinical trials among patients with cancer.

Vitamin E and cancer prevention: Studies with different forms of tocopherols and tocotrienols

α-Tocopherol (α-T) is the major form of vitamin E (VE) in animals and has the highest activity in carrying out the essential antioxidant functions of VE. Because of the involvement of oxidative stress in carcinogenesis, the cancer prevention activity of α-T has been studied extensively. Lower VE intake or nutritional status has been shown to be associated with increased cancer risk, and supplementation of α-T to populations with VE insufficiency has shown beneficial effects in lowering the cancer risk in some intervention studies. However, several large intervention studies with α-T conducted in North America have not demonstrated a cancer prevention effect. More recent studies have centered on the γ- and δ-forms of tocopherols and tocotrienols (T3). In comparison with α-T, these forms have much lower systemic bioavailability but have shown stronger cancer-preventive activities in many studies in animal models and cell lines. γ-T3 and δ-T3 generally have even higher activities than γ-T and δ-T. In this article, we review recent results from human and laboratory studies on the cancer-preventive activities of different forms of tocopherols and tocotrienols, at nutritional and pharmacological levels. We aim to elucidate the possible mechanisms of the preventive actions and discuss the possible application of the available information for human cancer prevention by different VE forms.

Tocopherols and Tocotrienols Are Bioavailable in Rats and Primarily Excreted in Feces as the Intact Forms and 13'-Carboxychromanol Metabolites

BACKGROUND

Vitamin E α-, γ-, or δ-tocopherol (αT, γT, δT) and γ- or δ-tocotrienol (γTE, δTE) are metabolized to hydroxychromanols and carboxychromanols including 13'-carboxychromanol (13'-COOH), 11'-COOH, and carboxyethyl hydroxychroman (CEHC), some of which have unique bioactivities compared with the vitamers. However, the bioavailability of these metabolites has not been well characterized.

OBJECTIVE

We investigated the pharmacokinetics (PK) of vitamin E forms and metabolites in rats.

METHODS

Six-week-old male Wistar rats received 1-time gavage of γT-rich tocopherols (50 mg/kg) containing γT/δT/αT (57.7%, 21.9%, and 10.9%, respectively) or δTE-rich tocotrienols (35 mg/kg) containing δTE/γTE (8:1). We quantified the time course of vitamin E forms and metabolites in the plasma and their 24-h excretion to the urine and feces. The general linear model repeated measure was used for analyses of the PK data.

RESULTS

In the rats' plasma, Cmax of γT or δTE was 25.6 ± 9.1 μM (Tmax = 4 h) or 16.0 ± 2.3 μM (Tmax = 2 h), respectively, and sulfated CEHCs and sulfated 11'-COOHs were the predominant metabolites with Cmax of 0.4-0.5 μM (Tmax ∼5-7 h) or ∼0.3 μM (Tmax at 4.7 h), respectively. In 24-h urine, 2.7% of γT and 0.7% of δTE were excreted as conjugated CEHCs. In the feces, 17-45% of supplemented vitamers were excreted as unmetabolized forms and 4.9-9.2% as unconjugated carboxychromanols, among which 13'-COOHs constituted ∼50% of total metabolites and the amount of δTE-derived 13'-COOHs was double that of 13'-COOH derived from γT.

CONCLUSIONS

PK data of vitamin E forms in rats reveal that γT, δT, γTE, and δTE are bioavailable in the plasma and are mainly excreted as unmetabolized forms and long-chain metabolites including 13'-COOHs in feces, with more metabolites from tocotrienols than from tocopherols.

Potential Role of Tocotrienols on Non-Communicable Diseases: A Review of Current Evidence

Tocotrienol (T3) is a subfamily of vitamin E known for its wide array of medicinal properties. This review aimed to summarize the health benefits of T3, particularly in prevention or treatment of non-communicable diseases (NCDs), including cardiovascular, musculoskeletal, metabolic, gastric, and skin disorders, as well as cancers. Studies showed that T3 could prevent various NCDs, by suppressing 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) in the mevalonate pathway, inflammatory response, oxidative stress, and alternating hormones. The efficacy of T3 in preventing/treating these NCDs is similar or greater compared to tocopherol (TF). TF may lower the efficacy of T3 because the efficacy of the combination of TF and T3 was lower than T3 alone in some studies. Data investigating the effects of T3 on osteoporosis, arthritis, and peptic ulcers in human are limited. The positive outcomes of T3 treatment obtained from the preclinical studies warrant further validation from clinical trials.

Beneficial effects of δ-tocotrienol against oxidative stress in osteoblastic cells: studies on the mechanisms of action

Purpose

Natural antioxidants are considered as promising compounds in the prevention/treatment of osteoporosis. We studied the ability of purified δ-tocotrienol (δ-TT) isolated from a commercial palm oil (Elaeis guineensis) fraction to protect osteoblast MC3T3-E1 and osteocyte MLO-Y4 cells against tert-butyl hydroperoxide (t-BHP)-induced oxidative damage and the mechanisms involved in its protective action in MC3T3-E1.

Methods

MC3T3-E1 and MLO-Y4 cells were treated with δ-TT (1.25–20 µg/ml for 2 h) followed by t-BHP at 250 µM or 125 µM for 3 h, respectively. MTT test was used to measure cell viability. Apoptotic cells were stained with Hoechst-33258 dye. Intracellular ROS levels were measured by dichlorofluorescein CM-DCFA. The OPT fluorimetric assay was used to detect the reduced glutathione to oxidized glutathione ratio (GSH/GSSG) contents.

Results

δ-TT significantly prevented the effects of t-BHP on cell viability and apoptosis reaching a maximum protective activity at 10 and 5 µg/ml in MC3T3-E1 and MLO-Y4 cells, respectively. This protective effect was due to a reduction of intracellular ROS levels and an increase in the defense systems shown by the increase in the GSH/GSSG. GSH loss induced by an inhibitor of GSH synthesis significantly reduced the δ-TT-positive effect on ROS levels. δ-TT prevention of oxidative damage was completely removed by combined treatment with the specific inhibitors of PI3K/AKT (LY294002) and Nrf2 (ML385).

Conclusions

The δ-TT protective effect against oxidative damage in MC3T3-E1 cells is due to a reduction of intracellular ROS levels and an increase of the GSH/GSSG ratio, and involves an interaction between the PI3K/Akt–Nrf2 signaling pathways.

δ-Tocotrienol induces apoptosis, involving endoplasmic reticulum stress and autophagy, and paraptosis in prostate cancer cells

OBJECTIVES

Prostate cancer, after the phase of androgen dependence, may progress to the castration-resistant prostate cancer (CRPC) stage, with resistance to standard therapies. Vitamin E-derived tocotrienols (TTs) possess a significant antitumour activity. Here, we evaluated the anti-cancer properties of δ-TT in CRPC cells (PC3 and DU145) and the related mechanisms of action.

MATERIALS AND METHODS

MTT, Trypan blue and colony formation assays were used to assess cell viability/cell death/cytotoxicity. Western blot, immunofluorescence and MTT analyses were utilized to investigate apoptosis, ER stress and autophagy. Morphological changes were investigated by light and transmission electron microscopy.

RESULTS

We demonstrated that δ-TT exerts a cytotoxic/proapoptotic activity in CRPC cells. We found that in PC3 cells: (a) δ-TT triggers both the endoplasmic reticulum (ER) stress and autophagy pathways; (b) autophagy induction is related to the ER stress, and this ER stress/autophagy axis is involved in the antitumour activity of δ-TT; in autophagy-defective DU145 cells, only the ER stress pathway is involved in the proapoptotic effects of δ-TT; (c) in both CRPC cell lines, δ-TT also induces an intense vacuolation prevented by the ER stress inhibitor salubrinal and the protein synthesis inhibitor cycloheximide, together with increased levels of phosphorylated JNK and p38, supporting the induction of paraptosis by δ-TT.

CONCLUSIONS

These data demonstrate that apoptosis, involving ER stress and autophagy (in autophagy positive PC3 cells), and paraptosis are involved in the anti-cancer activity of δ-TT in CRPC cells.

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.

Utilization of Vitamin E Analogs to Protect Normal Tissues While Enhancing Antitumor Effects

Despite advances in radiation delivery techniques, side effects of radiation therapy due to radiation exposure of normal tissues are common and can limit the deliverable dose to tumors. Significant interests lie in pharmacologic modifiers that may protect against normal tissue toxicity from cancer treatment while simultaneously enhancing the tumor response to therapy. While no such treatments are available in the clinic, this is an area of active preclinical and clinical research. This review summarizes research studies that provide evidence to indicate that tocotrienols, natural forms of vitamin E, are potent radiation protectors and may also have antitumor effects. Hence, several current clinical trials test tocotrienols as concomitant treatment in cancer therapies.

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.

De novo transcriptome assembly of the Chinese pearl barley, adlay, by full-length isoform and short-read RNA sequencing

Adlay (Coix lacryma-jobi) is a tropical grass that has long been used in traditional Chinese medicine and is known for its nutritional benefits. Recent studies have shown that vitamin E compounds in adlay protect against chronic diseases such as cancer and heart disease. However, the molecular basis of adlay's health benefits remains unknown. Here, we generated adlay gene sets by de novo transcriptome assembly using long-read isoform sequencing (Iso-Seq) and short-read RNA-Sequencing (RNA-Seq). The gene sets obtained from Iso-seq and RNA-seq contained 31,177 genes and 57,901 genes, respectively. We confirmed the validity of the assembled gene sets by experimentally analyzing the levels of prolamin and vitamin E biosynthesis-associated proteins in adlay plant tissues and seeds. We compared the screened adlay genes with known gene families from closely related plant species, such as rice, sorghum and maize. We also identified tissue-specific genes from the adlay leaf, root, and young and mature seed, and experimentally validated the differential expression of 12 randomly-selected genes. Our study of the adlay transcriptome will provide a valuable resource for genetic studies that can enhance adlay breeding programs in the future.

Natural forms of vitamin E and metabolites-regulation of cancer cell death and underlying mechanisms

The disappointing results from large clinical studies of α-tocopherol (αT), the major form of vitamin E in tissues, for prevention of chronic diseases including cancer have cast doubt on not only αT but also other forms of vitamin E regarding their role in preventing carcinogenesis. However, basic research has shown that specific forms of vitamin E such as γ-tocopherol (γT), δ-tocopherol (δT), γ-tocotrienol (γTE) and δ-tocotrienol (δTE) can inhibit the growth and induce death of many types of cancer cells, and are capable of suppressing cancer development in preclinical cancer models. For these activities, these vitamin E forms are much stronger than αT. Further, recent research revealed novel anti-inflammatory and anticancer effects of vitamin E metabolites including 13'-carboxychromanols. This review focuses on anti-proliferation and induction of death in cancer cells by vitamin E forms and metabolites, and discuss mechanisms underlying these anticancer activities. The existing in vitro and in vivo evidence indicates that γT, δT, tocotrienols and 13'-carboxychromanols have anti-cancer activities via modulating key signaling or mediators that regulate cell death and tumor progression, such as eicosanoids, NF-κB, STAT3, PI3K, and sphingolipid metabolism. These results provide useful scientific rationales and mechanistic understanding for further translation of basic discoveries to the clinic with respect to potential use of these vitamin E forms and metabolites for cancer prevention and therapy. © 2018 IUBMB Life, 71(4):495-506, 2019.

Vitamin E δ-tocotrienol inhibits TNF-α-stimulated NF-κB activation by up-regulation of anti-inflammatory A20 via modulation of sphingolipid including elevation of intracellular dihydroceramides

Nuclear factor-κB (NF-κB) regulates inflammation and cell survival, and is considered a potential target for anti-inflammatory and anti-cancer therapy. δ-Tocotrienol (δTE), a vitamin E form, has been shown to inhibit NF-κB, but the mechanism underlying this action is not clear. In the present study, we show that δTE inhibited TNF-α-induced activation of NF-κB and LPS-stimulated IL-6 in a dose- and time-dependent manner in Raw 264.7 macrophages. δTE potently inhibited TNF-α-induced phosphorylation of transforming growth factor β-activated kinase 1 (TAK1), an upstream kinase essential for the activation of NF-κB. Interestingly, δTE significantly increased the expression of A20 and to a less extent, cylindromatosis (CYLD), both of which are inhibitors of NF-κB. The importance of induction of A20 in δTE's anti-NF-κB effect is validated in A20 knockout cells where δTE's inhibition of NF-κB was largely diminished. In pursuit of the cause for A20 induction, we found that δTE treatment caused rapid and persistent elevation of dihydroceramides, while decreased ceramides initially but increased ceramides during prolonged treatment. These changes of sphingolipids were accompanied by increased cellular stress markers. Importantly, δTE's induction of A20 and inhibition of NF-κB activation were partially counteracted by myriocin, a potent inhibitor of de novo synthesis of sphingolipids, indicating a critical role of sphingolipid modulation in δTE-mediated effects. Since dihydroceramide has been shown to induce A20 and inhibit NF-κB in RAW cells, we conclude that that δTE inhibits NF-κB activation by enhancing its negative regulator A20 as a result of modulating sphingolipids especially elevation of dihydroceramides.

Vitamin E and its anticancer effects

Vitamin E is a lipid soluble vitamin comprising of eight natural isoforms, namely, α, β, δ, γ isoforms of tocopherol and α, β, δ, γ isoforms of tocotrienol. Many studies have been performed to elucidate its role in cancer. Until last decade, major focus was on alpha tocopherol and its anticancer effects. However, major clinical trials using alpha-tocopherol like SELECT trial and ATBC trial did not yield meaningful results. Hence there was a shift of focus to gamma-tocopherol, delta-tocopherol and tocotrienol. Unlike alpha-tocopherol, gamma-tocopherol and delta-tocopherol can scavenge reactive nitrogen species in addition to reactive oxygen species. Antiangiogenic effect, inhibition of HMG CoA reductase enzyme and inhibition of NF-κB pathway make the anti-cancer effects of tocotrienols unique compared to other vitamin E isoforms. Preclinical research on non-alpha tocopherol isoforms of vitamin E showed promising data on their anticancer effects. In this review, we deal with the current understanding on the potential mechanisms involved in the anticancer effects of vitamin E and the controversies in this field over last three decades. We also highlight the need to conduct further research on the anticancer effects of non-alpha-tocopherol isoforms in larger population and clinical setting.

Anticancer properties of tocotrienols: A review of cellular mechanisms and molecular targets

Vitamin E is composed of two groups of compounds: α-, β-, γ-, and δ-tocopherols (TPs), and the corresponding unsaturated tocotrienols (TTs). TTs are found in natural sources such as red palm oil, annatto seeds, and rice bran. In the last decades, TTs (specifically, γ-TT and δ-TT) have gained interest due to their health benefits in chronic diseases, based on their antioxidant, neuroprotective, cholesterol-lowering, anti-inflammatory activities. Several in vitro and in vivo studies pointed out that TTs also exert a significant antitumor activity in a wide range of cancer cells. Specifically, TTs were shown to exert antiproliferative/proapoptotic effects and to reduce the metastatic or angiogenic properties of different cancer cells; moreover, these compounds were reported to specifically target the subpopulation of cancer stem cells, known to be deeply involved in the development of resistance to standard therapies. Interestingly, recent studies pointed out that TTs exert a synergistic antitumor effect on cancer cells when given in combination with either standard antitumor agents (i.e., chemotherapeutics, statins, "targeted" therapies) or natural compounds with anticancer activity (i.e., sesamin, epigallocatechin gallate (EGCG), resveratrol, ferulic acid). Based on these observations, different TT synthetic derivatives and formulations were recently developed and demonstrated to improve TT water solubility and to reduce TT metabolism in cancer cells, thus increasing their biological activity. These promising results, together with the safety of TT administration in healthy subjects, suggest that these compounds might represent a new chemopreventive or anticancer treatment (i.e., in combination with standard therapies) strategy. Clinical trials aimed at confirming this antitumor activity of TTs are needed.

A 12-week evaluation of annatto tocotrienol supplementation for postmenopausal women: safety, quality of life, body composition, physical activity, and nutrient intake

BACKGROUND

Evidence suggests that tocotrienols may benefit bone health in osteopenic women. However, their safety in this population has never been investigated. This study was to evaluate the safety of a 12-week supplementation of annato tocotrienol in postmenopausal osteopenic women, along with effects of the supplementation on quality of life, body composition, physical activity, and nutrient intake in this population.

METHODS

Eighty nine postmenopausal osteopenic women were randomly assigned to 3 treatment arms: (1) Placebo (430 mg olive oil/day), (2) Low tocotrientol (Low TT) (430 mg tocotrienol/day from DeltaGold 70 containing 300 mg tocotrienol) and (3) High tocotrienol (High TT) (860 mg tocotrienol/day from DeltaGold 70 containing 600 mg tocotrienol) for 12 weeks. DeltaGold 70 is an extract from annatto seed with 70% tocotrienol consisting of 90% delta-tocotrienol and 10% gamma-tocotrienol. Safety was examined by assessing liver enzymes (aspartate aminotransferase, alanine aminotransferase), alkaline phosphatase, bilirubin, kidney function (blood urea nitrogen and creatinine), electrolytes, glucose, protein, albumin, and globulin at 0, 6, and 12 weeks. Serum tocotrienol and tocopherol concentrations were assessed and pills counted at 0, 6, and 12 weeks. Quality of life, body composition, physical activity, and dietary macro- and micro-nutrient intake were evaluated at 0 and 12 weeks. A mixed model of repeated measures ANOVA was applied for analysis.

RESULTS

Eighty seven subjects completed the study. Tocotrienol supplementation did not affect liver or kidney function parameters throughout the study. No adverse event due to treatments was reported by the participants. Tocotrienol supplementation for 6 weeks significantly increased serum delta-tocotrienol level and this high concentration was sustained to the end of study. There was no difference in serum delta-tocotrienol levels between the Low TT and the High TT groups. No effects of tocotrienol supplementation were observed on quality of life, body composition, physical activity, and nutrient intake.

CONCLUSIONS

Annatto-derived tocotrienol up to 600 mg per day for 12 weeks appeared to be safe in postmenopausal osteopenic women, particularly in terms of liver and kidney functions. Tocotrienol supplementation for 12 weeks did not affect body composition, physical activity, quality of life, or intake of macro- and micro-nutrients in these subjects.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02058420 .

TITLE

Tocotrienols and bone health of postmenopausal women.

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

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.

Antioxidant Tocols as Radiation Countermeasures (Challenges to be Addressed to Use Tocols as Radiation Countermeasures in Humans)

Radiation countermeasures fall under three categories, radiation protectors, radiation mitigators, and radiation therapeutics. Radiation protectors are agents that are administered before radiation exposure to protect from radiation-induced injuries by numerous mechanisms, including scavenging free radicals that are generated by initial radiochemical events. Radiation mitigators are agents that are administered after the exposure of radiation but before the onset of symptoms by accelerating the recovery and repair from radiation-induced injuries. Whereas radiation therapeutic agents administered after the onset of symptoms act by regenerating the tissues that are injured by radiation. Vitamin E is an antioxidant that neutralizes free radicals generated by radiation exposure by donating H atoms. The vitamin E family consists of eight different vitamers, including four tocopherols and four tocotrienols. Though alpha-tocopherol was extensively studied in the past, tocotrienols have recently gained attention as radiation countermeasures. Despite several studies performed on tocotrienols, there is no clear evidence on the factors that are responsible for their superior radiation protection properties over tocopherols. Their absorption and bioavailability are also not well understood. In this review, we discuss tocopherol's and tocotrienol's efficacy as radiation countermeasures and identify the challenges to be addressed to develop them into radiation countermeasures for human use in the event of radiological emergencies.

Inducers of Senescence, Toxic Compounds, and Senolytics: The Multiple Faces of Nrf2-Activating Phytochemicals in Cancer Adjuvant Therapy

The reactivation of senescence in cancer and the subsequent clearance of senescent cells are suggested as therapeutic intervention in the eradication of cancer. Several natural compounds that activate Nrf2 (nuclear factor erythroid-derived 2-related factor 2) pathway, which is involved in complex cytoprotective responses, have been paradoxically shown to induce cell death or senescence in cancer. Promoting the cytoprotective Nrf2 pathway may be desirable for chemoprevention, but it might be detrimental in later stages and advanced cancers. However, senolytic activity shown by some Nrf2-activating compounds could be used to target senescent cancer cells (particularly in aged immune-depressed organisms) that escape immunosurveillance. We herein describe in vitro and in vivo effects of fifteen Nrf2-interacting natural compounds (tocotrienols, curcumin, epigallocatechin gallate, quercetin, genistein, resveratrol, silybin, phenethyl isothiocyanate, sulforaphane, triptolide, allicin, berberine, piperlongumine, fisetin, and phloretin) on cellular senescence and discuss their use in adjuvant cancer therapy. In light of available literature, it can be concluded that the meaning and the potential of adjuvant therapy with natural compounds in humans remain unclear, also taking into account the existence of few clinical trials mostly characterized by uncertain results. Further studies are needed to investigate the therapeutic potential of those compounds that display senolytic activity.

Tocotrienol is a cardioprotective agent against ageing-associated cardiovascular disease and its associated morbidities

Ageing is a nonmodifiable risk factor that is linked to increased likelihood of cardiovascular morbidities. Whilst many pharmacological interventions currently exist to treat many of these disorders such as statins for hypercholesterolemia or beta-blockers for hypertension, the elderly appear to present a greater likelihood of suffering non-related side effects such as increased risk of developing new onset type 2 diabetes (NODM). In some cases, lower efficacy in the elderly have also been reported. Alternative forms of treatment have been sought to address these issues, and there has been a growing interest in looking at herbal remedies or plant-based natural compounds. Oxidative stress and inflammation are implicated in the manifestation of ageing-related cardiovascular disease. Thus, it is natural that a compound that possesses both antioxidative and anti-inflammatory bioactivities would be considered. This review article examines the potential of tocotrienols, a class of Vitamin E compounds with proven superior antioxidative and anti-inflammatory activity compared to tocopherols (the other class of Vitamin E compounds), in ameliorating ageing-related cardiovascular diseases and its associated morbidities. In particular, the potential of tocotrienols in improving inflammaging, dyslipidemia and mitochondrial dysfunction in ageing-related cardiovascular diseases are discussed.

Natural Forms of Vitamin E as Effective Agents for Cancer Prevention and Therapy

Initial research on vitamin E and cancer has focused on α-tocopherol (αT), but recent clinical studies on cancer-preventive effects of αT supplementation have shown disappointing results, which has led to doubts about the role of vitamin E, including different vitamin E forms, in cancer prevention. However, accumulating mechanistic and preclinical animal studies show that other forms of vitamin E, such as γ-tocopherol (γT), δ-tocopherol (δT), γ-tocotrienol (γTE), and δ-tocotrienol (δTE), have far superior cancer-preventive activities than does αT. These vitamin E forms are much stronger than αT in inhibiting multiple cancer-promoting pathways, including cyclo-oxygenase (COX)- and 5-lipoxygenase (5-LOX)-catalyzed eicosanoids, and transcription factors such as nuclear transcription factor κB (NF-κB) and signal transducer and activator of transcription factor 3 (STAT3). These vitamin E forms, but not αT, cause pro-death or antiproliferation effects in cancer cells via modulating various signaling pathways, including sphingolipid metabolism. Unlike αT, these vitamin E forms are quickly metabolized to various carboxychromanols including 13'-carboxychromanols, which have even stronger anti-inflammatory and anticancer effects than some vitamin precursors. Consistent with mechanistic findings, γT, δT, γTE, and δTE, but not αT, have been shown to be effective for preventing the progression of various types of cancer in preclinical animal models. This review focuses on cancer-preventive effects and mechanisms of γT, δT, γTE, and δTE in cells and preclinical models and discusses current progress in clinical trials. The existing evidence strongly indicates that these lesser-known vitamin E forms are effective agents for cancer prevention or as adjuvants for improving prevention, therapy, and control of cancer.

Regulation of cell signaling pathways by dietary agents for cancer prevention and treatment

Although it is widely accepted that better food habits do play important role in cancer prevention and treatment, how dietary agents mediate their effects remains poorly understood. More than thousand different polyphenols have been identified from dietary plants. In this review, we discuss the underlying mechanism by which dietary agents can modulate a variety of cell-signaling pathways linked to cancer, including transcription factors, nuclear factor κB (NF-κB), signal transducer and activator of transcription 3 (STAT3), activator protein-1 (AP-1), β-catenin/Wnt, peroxisome proliferator activator receptor- gamma (PPAR-γ), Sonic Hedgehog, and nuclear factor erythroid 2 (Nrf2); growth factors receptors (EGFR, VEGFR, IGF1-R); protein Kinases (Ras/Raf, mTOR, PI3K, Bcr-abl and AMPK); and pro-inflammatory mediators (TNF-α, interleukins, COX-2, 5-LOX). In addition, modulation of proteasome and epigenetic changes by the dietary agents also play a major role in their ability to control cancer. Both in vitro and animal based studies support the role of dietary agents in cancer. The efficacy of dietary agents by clinical trials has also been reported. Importantly, natural agents are already in clinical trials against different kinds of cancer. Overall both in vitro and in vivo studies performed with dietary agents strongly support their role in cancer prevention. Thus, the famous quote "Let food be thy medicine and medicine be thy food" made by Hippocrates 25 centuries ago still holds good.

Oxidative Stress: A New Target for Pancreatic Cancer Prognosis and Treatment

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal types of tumors, and its incidence is rising worldwide. Survival can be improved when tumors are detected at an early stage; however, this cancer is usually asymptomatic, and the disease only becomes apparent after metastasis. Several risk factors are associated to this disease. Chronic pancreatitis, diabetes, and some infectious disease are the most relevant risk factors. Incidence of PDAC has increased in the last decades. It is hypothesized it could be due to other acquired risk habits, like smoking, high alcohol intake, and obesity. Indeed, adipose tissue is a dynamic endocrine organ that secretes different pro-inflammatory cytokines, enzymes, and other factors that activate oxidative stress. Reactive oxygen species caused by oxidative stress, damage DNA, proteins, and lipids, and produce several toxic and high mutagenic metabolites that could modify tumor behavior, turning it into a malignant phenotype. Anti-oxidant compounds, like vitamins, are considered protective factors against cancer. Here, we review the literature on oxidative stress, the molecular pathways that activate or counteract oxidative stress, and potential treatment strategies that target reactive oxygen species suitable for this kind of cancer.