γ-Tocotrienol-induced disruption of lipid rafts in human breast cancer cells is associated with a reduction in exosome heregulin content

Induced Self-Assembly of Vitamin E-Spermine/siRNA Nanocomplexes via Spermine/Helix Groove-Specific Interaction for Efficient siRNA Delivery and Antitumor Therapy

Gene therapy has been one of potential strategies for the treatment of different diseases, where efficient and safe gene delivery systems are also extremely in need. Current lipid nanoparticles (LNP) technology highly depends on the packing and condensation of nucleic acids with amine moieties. Here, an attempt to covalently link two natural compounds, spermine and vitamin E, is made to develop self-assembled nucleic acid delivery systems. Among them, the spermine moieties specifically interact with the major groove of siRNA helix through salt bridge interaction, while vitamin E moieties are located around siRNA duplex. Such amphiphilic vitamin E-spermine/siRNA complexes can further self-assemble into nanocomplexes like multiblade wheels. Further studies indicate that these siRNA nanocomplexes with the neutrally charged surface of vitamin E can enter cells via caveolin/lipid raft mediated endocytosis pathway and bypass lysosome trapping. With these self-assembled delivery systems, efficient siRNA delivery is successfully achieved for Eg5 and Survivin gene silencing as well as DNA plasmid delivery. Further in vivo study indicates that VE-Su-Sper/DSPE-PEG2000/siSurvivin self-assembled nanocomplexes can accumulate in cancer cells and gradually release siRNA in tumor tissues and show significant antitumor effect in vivo. The self-assembled delivery system provides a novel strategy for highly efficient siRNA delivery.

The potential role of extracellular vesicles in bioactive compound-based therapy: A review of recent developments

Recent studies have explored the field of extracellular vesicles (EVs), driving an increasing interest in their application to human health. EVs have unique physicochemical traits to participate in intercellular communication, thus fostering the idea of using EVs to yield synergistic, preventive, and therapeutic effects. Many reports have shown that EVs contain natural bioactive compounds, such as lipids, proteins, RNA, and other active components that regulate biological processes, thereby contributing to human health. Therefore, in this review, we comprehensively elucidate various facets of the relationship between EVs and bioactive compounds that modulate EVs contents, including RNAs and proteins, discussing different forms of biological regulation. The use of EVs for cargo-loading bioactive compounds to exert biological functions and methods to load bioactive compounds into EVs are also discussed. This review highlighted the effect of EV-delivered bioactive compounds on several therapeutic mechanisms and applications, providing new insight into nutrition and pharmacology.

New Methodology for Accurate Determination of Molecular Co-localization at the Nanoscale

A new methodology using nanoparticle projectile secondary ion mass spectrometry was developed to identify statistically significant co-localization of tagged proteins versus random aggregations at the nanoscale. The custom instrument was run in the unique event-by-event bombardment detection mode with 1040 keV Au₂₈₀₀⁸⁺ individual projectiles each probing an area with a diameter of ∼20 nm. In a model experiment, antibodies tagged with fluorine, iodine, and bromine were attached on a silicon wafer in a 1:1:1 ratio. To determine whether the three different antibodies were homogeneously distributed at the nanoscale or if there were fluctuations due to the slightly different physical properties of the tags, a "co-localization factor" was introduced. It is shown for the first time that the differences in the hydrophobicity of the tags induced fluctuations, causing differential attachment of the tags at the nanoscale. When tags with the same physical and chemical properties were used, the analysis of co-localization factors shows that the attachment became random.

δ-Tocotrienol is the most potent vitamin E form in inhibiting prostate cancer cell growth and inhibits prostate carcinogenesis in Ptenp-/- mice

Vitamin E compounds, consisting of α, β, γ, and δ forms of tocopherols and tocotrienols, display different cancer preventive activities in experimental models. Tocotrienols may have higher potential for clinical use due to their lower effective doses in laboratory studies. However, most studies on tocotrienols have been carried out using cancer cell lines. Strong data from animal studies may encourage the use of tocotrienols for human cancer prevention research. To examine the cancer inhibitory activity of different vitamin E forms, we first investigated their inhibitory activities of different vitamin E forms in prostate cancer cell lines. We found that δ-tocotrienol (δT3) was the most effective form in inhibiting cell growth at equivalent doses. Because of this in vitro potency, δT3 was further studied using prostate specific Pten-/- (Ptenp-/-) mice. We found that 0.05% δT3 in diet reduced prostate adenocarcinoma multiplicity by 32.7%, featuring increased apoptosis and reduced cell proliferation. The inhibitory effect of 0.05% δT3 in diet was similar to that of 0.2% δ-tocopherol (δT) in diet reported previously. Our further study on the δT3-induced transcriptome changes indicated that δT3 inhibited genes in blood vessel development in the prostate of Ptenp-/- mice, which was confirmed by immunohistochemistry. Together, our results demonstrate that δT3 effectively inhibits the development of prostate adenocarcinoma in Ptenp-/- mice, which involves inhibition of proliferation and angiogenesis and promotion of apoptosis.

Cholesterol and Sphingolipid Enriched Lipid Rafts as Therapeutic Targets in Cancer

Lipid rafts are critical cell membrane lipid platforms enriched in sphingolipid and cholesterol content involved in diverse cellular processes. They have been proposed to influence membrane properties and to accommodate receptors within themselves by facilitating their interaction with ligands. Over the past decade, technical advances have improved our understanding of lipid rafts as bioactive structures. In this review, we will cover the more recent findings about cholesterol, sphingolipids and lipid rafts located in cellular and nuclear membranes in cancer. Collectively, the data provide insights on the role of lipid rafts as biomolecular targets in cancer with good perspectives for the development of innovative therapeutic strategies.

The roles of exosomes in cancer drug resistance and its therapeutic application

Exosomes are a category of extracellular vesicles with a size ranging from 40 to 160 nm, which can be secreted by multiple cells in the tumor microenvironment. Exosomes serve as communicators in regulating biological functions and pathological processes, including drug response. Through transporting the cargo such as protein or nucleic acid, exosomes can modulate drug sensitivity via multiple mechanisms. Additionally, exosomes can be deployed as a delivery system to treat cancer due to their high-efficient loading capacity and tolerable toxicity. Recent studies have demonstrated the high efficacy of exosomes in cancer therapy. Herein, we conduct this review to summarize the mechanism of exosome-mediated drug resistance and the therapeutic potential of exosomes in cancer.

10-Gingerol Targets Lipid Rafts Associated PI3K/Akt Signaling in Radio-Resistant Triple Negative Breast Cancer Cells

10-gingerol is a major phenolic lipid found in the rhizomes of ginger (Zingiber officinale). Being amphiphilic in nature, phenolic lipids have the ability to incorporate into cell membranes and modulate membrane properties. The purpose of the present study was to evaluate the effects of 10-gingerol on lipid raft/membrane raft modulation in radio-resistant triple negative breast cancer (MDA-MB-231/IR) cells. The effects of 10-gingerol on MDA-MB-231/IR cells' proliferation, clonogenic growth, migration, and invasion were assayed using MTT, colony formation, cell migration, and invasion assays, respectively. Sucrose density gradient centrifugation was used to extract lipid rafts. Western blotting and immunofluorescence were employed to assess the effects of 10-gingerol on lipid raft/membrane raft modulation and lipid rafts-associated PI3K/Akt signaling. Cholesterol measurements were carried out using a commercially available kit. 10-gingerol suppressed the proliferation, migration, invasion, and induced apoptosis through targeting the PI3K/Akt signaling pathway in MDA-MB-231/IR cells. Moreover, 10-gingerol was found to modulate the lipid rafts of MDA-MB-231/IR cells and attenuate the key PI3K/Akt signaling components in lipid rafts. The cholesterol content of the lipid rafts and rafts-resident Akt signaling were also affected by exposure to 10-gingerol. The results of the present study highlight rafts-associated PI3K/Akt signaling as a new target of 10-gingerol in MDA-MB-231/IR cells, thus rationalizing a new rafts-mediated treatment approach for radio-resistant triple negative breast cancer cells.

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.

Steroidal glycoalkaloids from Solanum lyratum inhibit the pro-angiogenic activity of A549-derived exosomes

In this study, seven previously undescribed steroidal glycoalkaloids, compounds 1-7, were isolated from Solanum lyratum, along with two known ones (8 and 9). Comprehensive spectroscopy techniques were used to determine their structures. Although 1-8 only showed a weak inhibitory effect on the proliferation of the tumor-derived vascular endothelial cells, however, in a former study we found both total steroidal glycoalkaloids from Solanum lyratum (TSGS) and 9 significantly inhibited tumor angiogenesis and its mechanism was linked to its ability to interfere with cell membrane lipid rafts. Lipid rafts are closely related to the functions of tumor-derived exosomes, a vital factor in cancer progression. Thus, we investigated the impacts of TSGS and 9 on the functions of A549-derived exosomes. Our results indicated that A549-derived exosomes can significantly enhance the angiogenesis abilities of human umbilical vein endothelial cells, whereas the intervention of TSGS or 9 significantly inhibited this activity of A549-derived exosomes. These findings suggest that TSGS and 9 exert anti-tumor angiogenesis by inhibiting the pro-angiogenic activity of A549-derived exosomes.

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.

Syntaxin 6: A novel predictive and prognostic biomarker in papillary renal cell carcinoma

Syntaxin 6 is a SNARE family protein known to play an important role in intracellular trafficking. Here, we examined the tumorogenic role of syntaxin 6 in renal cell carcinoma (RCC). The Cancer Genome Atlas (TCGA) was queried for clinicopathologic data and syntaxin 6 expression. We found a significant difference in overall survival (OS) between groups, with high syntaxin 6 expression correlating with decreased survival. When stratifying the data based on histological subtype, the papillary RCC subtype exhibited a significant correlation between syntaxin 6 expression and survival. Using ROC curve, we calculated the area under the curve (AUC) to determine the ability of syntaxin 6 to predict 3-year overall survival. The AUC for syntaxin 6 was 0.73, significantly higher compared to 0.52 for T stage. Next, syntaxin 6 expression was evaluated in clear cell (786-O and Caki-1) and papillary (Caki-2 and ACHN) RCC cells. Syntaxin 6 expression was higher in Caki-1 and ACHN RCC cells. Silencing of syntaxin 6 in ACHN cells significantly decreased the cell viability (p < 0.001). Overall, syntaxin 6 could be a prognostic biomarker for patients with papillary RCC and syntaxin 6 inhibitors hold promise as a novel therapy against RCC.

A Role of Tumor-Released Exosomes in Paracrine Dissemination and Metastasis

Metastatic diffusion is thought to be a multi-step phenomenon involving the release of cells from the primary tumor and their diffusion through the body. Currently, several hypotheses have been put forward in order to explain the origin of cancer metastasis, including epithelial⁻mesenchymal transition, mutagenesis of stem cells, and a facilitating role of macrophages, involving, for example, transformation or fusion hybridization with neoplastic cells. In this paradigm, tumor-secreted extracellular vesicles (EVs), such as exosomes, play a pivotal role in cell communications, delivering a plethora of biomolecules including proteins, lipids, and nucleic acids. For their natural role in shuttling molecules, EVs have been newly considered a part of the metastatic cascade. They have a prominent role in preparing the so-called "tumor niches" in target organs. However, recent evidence has pointed out an even more interesting role of tumor EVs, consisting in their ability to induce malignant transformation in resident mesenchymal stem cells. All in all, in this review, we discuss the multiple involvements of EVs in the metastatic cascade, and how we can exploit and manipulate EVs in order to reduce the metastatic spread of malignant tumors.

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.

Modifying exosome release in cancer therapy: How can it help?

The reciprocal interactions of cancer cells with their microenvironment constitute an inevitable aspect of tumor development, progression and response to treatment in all cancers. Such bilateral transactions also serve as the key scenario underlying the development of drug resistance in many cases finally determining the fate of the disease and survival. In this view, a class of extracellular vesicles (EV) known as exosomes (EX) have been shown in the past few years to be important mediators of local and remote cell-to-cell contact changing the activity of their target cells by introducing their content of proteins, non-coding RNAs, and membrane-associated small molecules. In addition to the direct targeting of cancer cells, which has been routinely undertaken by different means to date, parallel attempts to change the signaling network governed by tumor-derived exosomes (TDE) may offer a promising potential to be utilized in cancer therapy. TDE drive diverse functions in the body, most of which have been shown to act to the advantage of tumor progression; however, there are also several studies that report the good aspects of TDE the interruption of which may result in undesirable outcomes. In the present paper, we made an effort to address this important issue by reviewing the very recent literature on different aspects of EX biogenesis and regulation and the various bodily effects of TDE which have been uncovered to date. Moreover, we have reviewed the possible interventions that can be made in TDE release as an important stage of EX biogenesis. Finally, keeping a criticizing view, the advantages and disadvantages of such interventions have been discussed and the future prospect in the field has been outlined.

The Content of Tocols in South African Wheat; Impact on Nutritional Benefits

Wheat is a major component within human consumption, and due to the large intake of wheat, it has an impact on human nutritional health. This study aimed at an increased understanding of how the content and composition of tocols may be governed for increased nutritional benefit of wheat consumption. Therefore, ten South African wheat cultivars from three locations were fractionated into white and whole flour, the content and concentration of tocols were evaluated by high performance liquid chromatography (HPLC), and vitamin E activity was determined. The content and composition of tocols and vitamin E activity differed with fractionation, genotype, environment, and their interaction. The highest tocol content (59.8 mg kg^-1) was obtained in whole flour for the cultivar Elands grown in Ladybrand, while whole Caledon flour from Clarence resulted in the highest vitamin E activity (16.3 mg kg^-1). The lowest vitamin E activity (1.9 mg kg^-1) was found in the cultivar C1PAN3118 from Ladybrand. High values of tocotrienols were obtained in whole flour of the cultivars Caledon (30.5 mg kg^-1 in Clarens), Elands (35.5 mg kg^-1 in Ladybrand), and Limpopo (33.7 mg kg^-1 in Bultfontein). The highest tocotrienol to tocopherol ratio was found in white flour (2.83) due to higher reduction of tocotrienols than of tocopherols at fractionation. The quantity and composition of tocols can be governed in wheat flour, primarily by the selection of fractionation method at flour production, but also complemented by selection of genetic material and the growing environment.