Vitamin E inhibits cell proliferation and the activation of extracellular signal-regulated kinase during the promotion phase of lung tumorigenesis irrespective of antioxidative effect

Alpha-Tocopherol Levels in Patients With Dentigerous Cysts: A Cross-Sectional Study

Background Dentigerous cysts (DC) form due to fluid accumulation between the crown of the tooth and the reduced enamel epithelium. Due to the diverse clinical characteristics, such as ambiguity concerning their biological origins and the significance of timely diagnosis and detection of these lesions, researchers are presently motivated to undertake further investigations. The aim of the present study was to assess the amount of serum alpha-tocopherol in patients with DC and compare it with that of normal, healthy individuals. Methods A total sample size of n=34 was included in the current study. Group A, designated as the control group, comprised 17 randomly selected healthy subjects, while Group B, the DC diagnostic group, consisted of 17 patients. Blood samples were collected, and the concentration of vitamin E or alpha-tocopherol was evaluated and expressed in mg/mL. Results Compared to the mean vitamin E level in healthy controls (12.08 ± 1.92 mg/mL), patients with DC showed a statistically significant (p<0.0001) reduction in mean vitamin E levels (5.29 ± 1.01 mg/mL). Conclusion Patients with DC have lower levels of vitamin E than healthy individuals. The reduced concentration of vitamin E can have a role in the extension of cystic volume and thus have an impact on the aggressiveness of pathologic lesions. The therapeutic benefits of vitamin E supplementation in reducing the aggressiveness of DC should be evaluated in future research.

Expression Profiling of Selected Immune Genes and Trabecular Microarchitecture in Breast Cancer Skeletal Metastases Model: Effect of α-Tocopherol Acetate Supplementation

Breast cancer bone metastases (BCBM) result in serious skeletal morbidity. Although there have been important advances in cancer treatment methods such as surgery and chemotherapy, the complementary treatments, such as α-tocopherol acetate (ATA), still remain of key role via complementary and/or synergistic effects. The aim of this work was to study immune response in a rat model of BCBM due to Walker 256/B cells inoculation and the effect of ATA alone. Compared to the control group (CTRL), rat injected with Walker 256/B cells (5 × 10⁴) in the medullar cavity (W256 group) showed osteolytic damages with marked tumor osteolysis of both cancellous and trabecular bone as assessed by X-ray radiology, micro-computed tomography, and histology. Rats inoculated with Walker 256/B cells and treated with ATA (45 mg/kg BW, W256ATA group) presented marked less tumor osteolysis, less disturbance of Tb.Th and Tb.Sp associated with conversion of rods into plates, and increased structure model index and trabecular pattern factor (Tb.Pf). Elsewhere, 3D frequency distributions of Tb.Th and Tb.Sp were highly disturbed in metastatic W256 rats. Overexpression of some genes commonly associated with cancer and metastatic proliferation: COX-2, TNF-α, and pro-inflammatory interleukins 1 and 6 was outlined. ATA alleviated most of the Walker 256/B cells-induced microarchitectural changes in the target parameters without turning back to normal levels. Likewise, it alleviates the BCSM-induced overexpression of COX-2, TNF-α, IL-1, and IL-6. In silico approach showed that ATA bound these proteins with high affinities, which satisfactory explain its beneficial effects. In conclusion, BCBM is associated with bone microarchitectural disorders and an immune response characterized by an overexpression of some key role genes in cancer proliferation and invasion. ATA exerted favorable effects on trabecular bone distribution and morphology, which may involve the COX-2, TNF-α, and ILs pathways.

How vitamin E and its derivatives regulate tumour cells via the MAPK signalling pathway?'

In tumour cells, vitamin E and its derivatives play a critical role in the regulation of multiple signalling pathways through their oxidative and nonoxidative functions. To date, there are 8 known natural vitamin E forms and many kinds of derivatives, among which VES and α-TEA have excellent anticancer activities. The MAPK pathway consists of a complex cascade of proteins that control the proliferation, differentiation and apoptosis of tumour cells. The MAPK pathway includes four subfamilies, ERK1/2, JNK1/2, p38 MAPK, and ERK5. Most of the proteins in these subfamilies interact with each other in a complex manner. The anticancer function of vitamin E and its derivatives is closely related to the MAPK cascade. Studies have shown that in tumour cells, α-T/γ-T/γ-T3/δ-T3/VES/α-TEA regulated ERK1/2, prevent tumorigenesis, inhibit tumour cell growth and metastasis and induce cell differentiation, apoptosis, and cell cycle arrest; γ-T3/δ-T3/VES/α-TEA regulates JNK1/2, induce apoptosis, reduce ceramide synthesis and inhibit proliferation; and γ-T3/δ-T3/VES regulate p38 MAPK and induce apoptosis. This paper reviews the role of vitamin E and its derivatives in the MAPK cascade, and tumour cells are used as a model in an attempt to explore the mechanism of their interactions.

Chitosan-Decorated PLGA-NPs Loaded with Tannic Acid/Vitamin E Mitigate Colon Cancer via the NF-κB/β-Cat/EMT Pathway

Colon cancer is the second highest contributor of cancer-related deaths throughout the world. Treatment strategies with tannic acid and vitamin E are envisaged as desirable and safe owing to their robust antioxidative and anti-inflammatory potential. In the present report, these bioactives have been nanoencapsulated in poly(d,l-lactide-co-glycolic acid) (PLGA) formulations for maintaining sustained release and ensuring enhanced bioavailability. Capping of nanoparticles (NPs) with chitosan was done for enhanced anticancer efficacy and tumor targeting. CS-PLGA-TA-E, administered intraperitoneally, significantly inhibited tumor number and tumor volume and normalized colon histology in the colon cancer. Tissue distribution studies showed that TA/E content from CS-PLGA-TA-E was present in a higher concentration in the tumor tissue than the concentration of TA/E content from PLGA-TA-E or free TA or free E. Also, the TA/E content from all of the treatment groups showed its highest concentration in the tumor compared to other organs. Antioxidant enzymes and proinflammatory cytokines (TNF-α, IL-1β, IL-6) were inhibited by CS-PLGA-TA-E. CS-PLGA-TA-E inhibited markers for tumor growth (EGFR-PI3K-AKT), inflammation (NF-κB/Stat3), β-catenin signaling (β-catenin, c-myc, cyclin D1), EMT (E-cadherin, N-cadherin, vimentin), and apoptosis (Bcl-2) in a significantly greater way as compared with PLGA-TA-E, TA, or E. CS-PLGA-TA-E NPs can be considered promising anticancer drugs for colon cancer.

Tannic acid and vitamin E loaded PLGA nanoparticles ameliorate hepatic injury in a chronic alcoholic liver damage model via EGFR-AKT-STAT3 pathway

Aim: Tannic acid and vitamin E loaded-poly D, L-lactide-co-glycolic acid (PLGA) nanoparticles (NP) were developed to achieve hepatoprotection in alcoholic liver disease mice model. Materials & methods: PLGA NPs were formed by emulsion solvent evaporation and characterized and delivered to mice. Histology studies were performed, serum enzyme levels of AST, ALT and inflammatory cytokines were checked using ELISA kits. Confocal microscopy and western blot analysis were utilized to determine protein expression levels, and docking studies were performed for interaction analysis. Results: PLGA NPs provided hepatoprotection by reducing inflammatory load, preventing reactive oxygen species generation and apoptosis, as well as by inhibiting the EGFR-AKT-STAT3 pathway. Conclusion: PLGA NPs of tannic acid and vitamin E could be a future medication for alcoholic liver disease treatment.

Effects of α-tocopherol on bone marrow mesenchymal cells derived from type II diabetes mellitus rats

It is widely accepted that vitamin E (VE) acts as an antioxidant and is involved in various metabolic systems including the regulation of gene expression and inhibition of cell proliferation. The most predominant isoform of VE in the living body is α-tocopherol. However, the influence of α-tocopherol on bone marrow mesenchymal cells (BMMCs) in a background of type II diabetes mellitus (DM) has not been investigated. The focus of the present study was to clarify the effect of α-tocopherol on BMMCs derived from rats with type II DM and the underlying mechanisms involved. BMMCs were isolated from rats with type II DM. The BMMCs were either untreated or exposed to α-tocopherol at concentrations of 1.0, 10, and 100 μM, and the resulting effects of α-tocopherol on cell proliferation, H₂O₂ activity, and antioxidant and inflammatory cytokine production were examined. At 100 μM, α-tocopherol had no effect on cell proliferation, but H₂O₂ activity was significantly increased. At 10 μM, α-tocopherol increased the gene expression of IL-1β, and markedly promoted that of TNF-α. Expression of catalase in the presence of 100 μM α-tocopherol was lower than for the other concentrations. At a low concentration, α-tocopherol exerted good antioxidant and anti-inflammatory effects on BMMCs. The study suggests that maintaining α-tocopherol at a low concentration might promote the recovery of BMMCs from oxidative stress.

Vitamin E: Regulatory Role on Signal Transduction

Vitamin E modulates signal transduction pathways by several molecular mechanisms. As a hydrophobic molecule located mainly in membranes it contributes together with other lipids to the physical and structural characteristics such as membrane stability, curvature, fluidity, and the organization into microdomains (lipid rafts). By acting as the main lipid-soluble antioxidant, it protects other lipids such as mono- and poly-unsaturated fatty acids (MUFA and PUFA, respectively) against chemical reactions with reactive oxygen and nitrogen species (ROS and RNS, respectively) and prevents membrane destabilization and cellular dysfunction. In cells, vitamin E affects signaling in redox-dependent and redox-independent molecular mechanisms by influencing the activity of enzymes and receptors involved in modulating specific signal transduction and gene expression pathways. By protecting and preventing depletion of MUFA and PUFA it indirectly enables regulatory effects that are mediated by the numerous lipid mediators derived from these lipids. In recent years, some vitamin E metabolites have been observed to affect signal transduction and gene expression and their relevance for the regulatory function of vitamin E is beginning to be elucidated. In particular, the modulation of the CD36/FAT scavenger receptor/fatty acids transporter by vitamin E may influence many cellular signaling pathways relevant for lipid homeostasis, inflammation, survival/apoptosis, angiogenesis, tumorigenesis, neurodegeneration, and senescence. Thus, vitamin E has an important role in modulating signal transduction and gene expression pathways relevant for its uptake, distribution, metabolism, and molecular action that when impaired affect physiological and patho-physiological cellular functions relevant for the prevention of a number of diseases. © 2018 IUBMB Life, 71(4):456-478, 2019.

α-Tocopherol at Nanomolar Concentration Protects Cortical Neurons against Oxidative Stress

The aim of the present work is to study the mechanism of the α-tocopherol (α-T) protective action at nanomolar and micromolar concentrations against H₂O₂-induced brain cortical neuron death. The mechanism of α-T action on neurons at its nanomolar concentrations characteristic for brain extracellular space has not been practically studied yet. Preincubation with nanomolar and micromolar α-T for 18 h was found to increase the viability of cortical neurons exposed to H₂O₂; α-T effect was concentration-dependent in the nanomolar range. However, preincubation with nanomolar α-T for 30 min was not effective. Nanomolar and micromolar α-T decreased the reactive oxygen species accumulation induced in cortical neurons by the prooxidant. Using immunoblotting it was shown that preincubation with α-T at nanomolar and micromolar concentrations for 18 h prevented Akt inactivation and decreased PKCδ activation induced in cortical neurons by H₂O₂. α-T prevented the ERK1/2 sustained activation during 24 h caused by H₂O₂. α-T at nanomolar and micromolar concentrations prevented a great increase of the proapoptotic to antiapoptotic proteins (Bax/Bcl-2) ratio, elicited by neuron exposure to H₂O₂. The similar neuron protection mechanism by nanomolar and micromolar α-T suggests that a “more is better” approach to patients’ supplementation with vitamin E or α-T is not reasonable.

An Assessment of Oxidative Damage and Non-Enzymatic Antioxidants Status Alteration in Relation to Disease Progression in Breast Diseases

The present study was aimed to evaluate the levels of oxidative stress markers in breast diseases by measuring the 8-hydroxy-2-deoxyguanosine (8-OHdG), vitamin A, vitamin C, vitamin E, and total antioxidant status (TAS) alterations in relation to cell proliferation activity and disease progression. Significant increases in the level of the oxidative damage marker 8-OHdG and cell proliferation activity were observed in breast carcinoma patients in comparison to benign and normal controls, which were accompanied by a significant decrease in non-enzymatic antioxidants and TAS concentrations (p < 0.05). 8-OHdG and cell proliferation levels were negatively correlated with non-enzymatic antioxidants, namely, vitamin A, vitamin C, and vitamin E levels and total antioxidant activity. Altered levels of biomarkers of oxidative stress and cell proliferation activity among the malignant, the benign, and the controls suggest a correlation of increased oxidative stress and cell proliferation activity in the progression of disease in breast carcinoma patients. In conclusion, our results showed that the characterized biomarkers (i.e., low levels of vitamin A, C and D, and the TAS status; and high levels of 8-OHdG) could be used as a suitable method for detecting subjects with malignant and benign breast diseases.

Effect of low-energy laser irradiation and antioxidant supplementation on cell apoptosis during skeletal muscle post-injury regeneration in pigs

The aim of this study was to evaluate the effect of low-energy laser irradiation, coenzyme Q10 and vitamin E supplementation on the apoptosis of macrophages and muscle precursor cells during skeletal muscle regeneration after bupivacaine-induced injury. The experiment was conducted on 75 gilts, divided into 5 experimental groups: I--control, II--low-energy laser irradiation, III--coenzyme Q10, IV--coenzyme Q10 and vitamin E, V--vitamin E. Muscle necrosis was induced by injection of 0.5% bupivacaine hydrochloride. The animals were euthanized on subsequent days after injury. Samples were formalin fixed and processed routinely for histopathology. Apoptosis was detected using the TUNEL method. The obtained results indicate that low-energy laser irradiation has a beneficial effect on macrophages and muscle precursor cell activity during muscle post-injury regeneration and protects these cells against apoptosis. Vitamin E has a slightly lower protective effect, limited mainly to the macrophages. Coenzyme Q10 co-supplemented with vitamin E increases the activity of macrophages and muscle precursor cells, myotube and young muscle formation. Importantly, muscle precursor cells seem to be more sensitive to apoptosis than macrophages in the environment of regenerating damaged muscle.

Protective effect of topical application of α-tocopherol and/or N-acetyl cysteine on argemone oil/alkaloid-induced skin tumorigenesis in mice

Since bioantioxidants in plasma of Epidemic Dropsy patients [a condition caused by consumption of adulterated mustard oil with argemone oil (AO)] were found to be significantly decreased, the beneficial effect of N-acetyl cysteine (NAC) and α-tocopherol (TOCO) against AO- or sanguinarine (SANG)-induced tumorigenicity was undertaken in mice. Topical application of TOCO and NAC either alone or in combination showed significant protection against AO/TPA- and SANG/TPA-induced skin tumorigenicity. Histopathological findings suggest that papillomatous growth in AO/TPA- and SANG/TPA-treated animals were substantially protected following topical application of TOCO or NAC. Further, treatment of TOCO and NAC either alone or in combination to AO/TPA- or SANG/TPA-induced mice significantly decreased lipid peroxidation, along with significant revival in glutathione (GSH) content and activities of tyrosinase, histidase, catalase, SOD, GSH peroxidase, and GSH reductase in skin. In vitro studies showed that TOCO and/or NAC significantly decreased the AO and SANG induced cell proliferation and activation of ERK, p38, JNK MAPKs and NF-κB signaling in HaCaT cells. In summary, TOCO and NAC may be useful in preventing the tumorigenic response of AO and SANG probably by acting as scavenger of free radicals and inhibiting MAPKs and NF-κB signaling.

α-Tocopherol at nanomolar concentration protects PC12 cells from hydrogen peroxide-induced death and modulates protein kinase activities

The aim of this work was to compare protective and anti-apoptotic effects of α-tocopherol at nanomolar and micromolar concentrations against 0.2 mM H(2)O(2)-induced toxicity in the PC12 neuronal cell line and to reveal protein kinases that contribute to α-tocopherol protective action. The protection by 100 nM α-tocopherol against H(2)O(2)-induced PC12 cell death was pronounced if the time of pre-incubation with α-tocopherol was 3-18 h. For the first time, the protective effect of α-tocopherol was shown to depend on its concentration in the nanomolar range (1 nM < 10 nM < 100 nM), if the pre-incubation time was 18 h. Nanomolar and micromolar α-tocopherol decreased the number of PC12 cells in late apoptosis induced by H(2)O(2) to the same extent if pre-incubation time was 18 h. Immunoblotting data showed that α-tocopherol markedly diminished the time of maximal activation of extracellular signal-regulated kinase 1/2 (ERK 1/2) and protein kinase B (Akt)-induced in PC12 cells by H(2)O(2). Inhibitors of MEK 1/2, PI 3-kinase and protein kinase C (PKC) diminished the protective effect of α-tocopherol against H(2)O(2)-initiated toxicity if the pre-incubation time was long. The modulation of ERK 1/2, Akt and PKC activities appears to participate in the protection by α-tocopherol against H(2)O(2)-induced death of PC12 cells. The data obtained suggest that inhibition by α-tocopherol in late stage ERK 1/2 and Akt activation induced by H(2)O(2) in PC12 cells makes contribution to its protective effect, while total inhibition of these enzymes is not protective.

Combined α-tocopherol and ascorbic acid protects against smoke-induced lung squamous metaplasia in ferrets

Many epidemiological studies show the benefit of fruits and vegetables on reducing risk of lung cancer, the leading cause of cancer death in the United States. Previously, we demonstrated that cigarette smoke exposure (SM)-induced lung lesions in ferrets were prevented by a combination of low dose of β-carotene, α-tocopherol (AT), and ascorbic acid (AA). However, the role of a combination of AT and AA alone in the protective effect on lung carcinogenesis remains to be examined. In the present study, we investigated whether the combined AT (equivalent to ∼100 mg/day in the human) and AA (equivalent to ∼210 mg/day) supplementation prevents against SM (equivalent to 1.5 packs of cigarettes/day) induced lung squamous metaplasia in ferrets. Ferrets were treated for 6 weeks in the following three groups (9 ferrets/group): (i) Control (no SM, no AT+AA), (ii) SM alone, and (iii) SM+AT+AA. Results showed that SM significantly decreased concentrations of retinoic acid, AT, and reduced form of AA, not total AA, retinol and retinyl palmitate, in the lungs of ferrets. Combined AT+AA treatment partially restored the lowered concentrations of AT, reduced AA and retinoic acid in the lungs of SM-exposed ferrets to the levels in the control group. Furthermore, the combined AT+AA supplementation prevented SM-induced squamous metaplasia [0 positive/9 total ferrets (0%) vs. 5/8 (62%); p<0.05] and cyclin D1 expression (p<0.05) in the ferret lungs, in which both were positively correlated with expression of c-Jun expression. Although there were no significant differences in lung microsomal malondialdehyde (MDA) levels among the three groups, we found a positive correlation between MDA levels and cyclin D1, as well as c-Jun expressions in the lungs of ferrets. These data indicate that the combination of antioxidant AT+AA alone exerts protective effects against SM-induced lung lesions through inhibiting cyclin D1 expression and partially restoring retinoic acid levels to normal.

Vitamin E analogues as mitochondria-targeting compounds: from the bench to the bedside?

Despite considerable effort focusing on designing and finding efficient anti-cancer drugs over the last decade, little progress has been achieved, in particular in case of highly recalcitrant malignancies. Also, since there is a trend suggesting that deaths from cancers may be more frequent than from cardiovascular diseases, it is important to look for novel efficient and selective therapeutic approaches to gradually start winning the battle with cancer. Redox-silent vitamin E analogues, epitomised by alpha-tocopheryl succinate, give some hope in the quest for drugs with such properties. Thus far, these agents have been successfully tested in experimental animals with different types of cancer, showing high efficacy against malignancies including HER2-positive breast carcinomas or malignant mesotheliomas. Further research will provide additional, necessary data to launch clinical trials, possibly in near future, translating into development of innovative anti-cancer drugs acting by targeting mitochondria selectively in cancer cells.

Modulation of signal transduction by vitamin E

The ability of vitamin E to modulate signal transduction and gene expression has been observed in numerous studies; however, the detailed molecular mechanisms involved are often not clear. The eight natural vitamin E analogues and synthetic derivatives affect signal transduction with different potency, possibly reflecting their different ability to interact with specific proteins. Vitamin E modulates the activity of several enzymes involved in signal transduction, such as protein kinase C, protein kinase B, protein tyrosine kinases, 5-, 12-, and 15-lipoxygenases, cyclooxygenase-2, phospholipase A2, protein phosphatase 2A, protein tyrosine phosphatase, and diacylglycerol kinase. Activation of some these enzymes after stimulation of cell surface receptors with growth factors or cytokines can be normalized by vitamin E. At the molecular level, the translocation of several of these enzymes to the plasma membrane is affected by vitamin E, suggesting that the modulation of protein-membrane interactions may be a common theme for vitamin E action. In this review the main effects of vitamin E on enzymes involved in signal transduction are summarized and the possible mechanisms leading to enzyme modulation evaluated. The elucidation of the molecular and cellular events affected by vitamin E could reveal novel strategies and molecular targets for developing similarly acting compounds.

?-Vitamin E derivative, RRR-?-tocopheryloxybutyric acid inhibits the proliferation of prostate cancer cells

AIM

To investigate the activity of RRR-alpha-tocopheryloxybutyric acid (TOB), an ether analog of RRR-alpha-tocopheryl succinate (VES), in prostate cancer cells.

METHODS

VES and TOB were used to treat prostate cancer LNCaP, PC3, and 22Rv1 cells and primary-cultured prostate fibroblasts. The proliferation rates were determined by MTT assay, the cell viabilities were determined by trypan blue exclusion assay, and the cell deaths were evaluated by using Cell Death Detection ELISA kit. The protein expression levels were determined by Western blot analysis.

RESULTS

The MTT growth assay demonstrated that TOB could effectively suppress the proliferation of prostate cancer cells, but not normal prostate fibroblasts. Mechanism dissections revealed that TOB reduced cell viability and induced apoptosis in prostate cancer cells similar to VES. In addition, both TOB and VES suppressed prostate-specific antigen (PSA) at the transcriptional level leading to reduced PSA protein expression. Furthermore, vitamin D receptor (VDR) expression increased after the addition of TOB.

CONCLUSION

Our data suggests that the VES derivative, TOB, is effective in inhibiting prostate cancer cell proliferation, suggesting that TOB could be used for both chemopreventive and chemotherapeutic purposes in the future.

Oxidative DNA damage and antioxidant vitamin level: comparison among lung cancer patients, healthy smokers and nonsmokers

In the present study, we examined whether the level of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) in leukocyte DNA is higher in lung cancer patients compared to controls. Factors that may influence oxidative stress, such as antioxidant vitamins, were also determined. These parameters were analyzed in 4 groups of subjects: smokers with lung cancer, ex-smokers with lung cancer, healthy smokers with comparable smoking status and healthy nonsmokers. The 8-oxodGuo mean level in leukocytes of lung cancer patients reached values of 9.22/10(6) dGuo molecules (smokers) and 11.16/10(6) dGuo molecules (ex-smokers). These values were significantly higher than in DNA of healthy smokers and nonsmokers, where mean levels reached 6.99/10(6) dGuo molecules and 5.98/10(6) dGuo molecules, respectively. Mean levels of vitamin C in the plasma of controls and lung cancer patients were 56.17 microM (nonsmokers), 26.34 microM (healthy smokers), 23.83 microM (cancer patients, smokers) and 29.19 microM (cancer patients, ex-smokers). The difference between nonsmokers and the 3 other groups was statistically significant. Vitamin E level was significantly reduced in the plasma of cancer patients (smokers 19.94 microM, ex-smokers 19.59 microM) compared to healthy smokers (28.93 microM). No changes in vitamin A concentration were found. Our results suggest that a high level of 8-oxodGuo in leukocyte DNA and a low concentration of vitamin E in the blood may predict lung cancer risk. However, it is also possible that these phenomena may simply result from disease development.

α-Tocopheryloxybutyric acid enhances necrotic cell death in breast cancer cells treated with chemotherapy agent

The overexpression of HER-2 receptor contributes to malignant transformation of breast cancer cells. We have reported that alpha-tocopheryloxybutyric acid (TE), non-antioxidative vitamin E ether derivative inhibits the activation of HER-2 receptor. The present study was undertaken to estimate if TE could act as a useful anti-cancer agent against a breast cancer cell overexpressing HER-2 receptor (MDA-MB-453 cell line) in combination with a conventional chemotherapy agent, adriamycin (ADR). TE enhanced cytotoxic effect of ADR against the human breast cancer cell at low doses less than IC(50). The enhancing effect was mainly dependent on the elevation of necrotic-like cell death but not apoptotic cell death. In conjugation with this event, the inactivation of HER-2 receptor in the breast cancer cell was caused by the combination of TE with ADR. These results suggest that TE enhances necrotic-like cell death in the breast cancer cells and that the cell death relates to the inactivation of HER-2 receptor in the breast cancer cells.

Cancer chemopreventive effects of oral feeding alpha-tocopherol on ultraviolet light B induced photocarcinogenesis of hairless mouse

Ultraviolet light is the most common cause of skin cancers in humans and several effects of ultraviolet light B (UVB: 290-320 nm) are thought to contribute to skin photocarcinogenesis. The generation of free radicals and related oxidants produced by UVB exposure, result in photocarcinogenesis by directly damaging DNA. On the other side, activating of transcription factor, activator protein 1 (AP-1) induced by UVB exposure causes tumor promotion. alpha-tocopherol has two principal physiological activities and one is an antioxidant activity through which alpha-tocopherol protects unsaturated fatty acids, protein and DNA from oxidation. The other activity is to stabilize the structure of the biomembrane. In addition to these two activities, it has been recently established that alpha-tocopherol plays important roles in cell signal transduction. In course of these studies, we examined such effects of alpha-tocopherol on UVB induced skin photocarcinogenesis in hairless mice. These results indicate that oral feeding of alpha-tocopherol including diet exhibited a marked inhibitory effects on both tumor incidence and multiplicity in UVB induced mouse skin photocarcinogenesis.

High oleic acid oil suppresses lung tumorigenesis in mice through the modulation of extracellular signal-regulated kinase cascade

This study was undertaken to estimate the effect of dietary high oleic acid oil (OA) on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis in mice. Diet containing 10% oil was fed to mice through experimental periods. On day 30 after NNK injection (100 mg/kg body weight, i.p.), the treatment increased the level of prostaglandin E2 (PGE2) as well as proliferating cell nuclear antigen, a marker of cell proliferation in a high linoleic acid oil (LA)-fed group but not in an OA-fed group. The NNK treatment also induced the activation of an extracellular signal-regulated kinase (Erk) cascade (Erk, Mek and Raf-1) in an LA-fed group. On the other hand, OA feeding abolished the NNK-induced activation of the Erk cascade. In conjugation with these events, OA feeding reduced lung tumor incidence and tumor multiplicity (percentage of mice with tumors) in mice compared with LA feeding at the 20th experimental week. These results suggest that OA suppresses lung tumorigenesis and that this suppression is correlated with the inhibition of PGE2 production and inactivation of the Erk cascade.

Induction of apoptosis in a human breast cancer cell overexpressing ErbB-2 receptor by alpha-tocopheryloxybutyric acid

The overexpression of ErbB-2 receptor relates to malignant transformation of breast cancer. The present study was carried out to establish the usefulness of alpha-tocopheryloxybutyric acid (TE) as a chemotherapeutic agent for human breast cancer. TE caused induction of apoptosis in MDA-MB-453 cells overexpressing the ErbB-2 receptor. TE reduced levels of activated ErbB-2 receptor and Akt. In contrast, TE induced the activation of p38, and SB203580, a specific inhibitor for p38, attenuated the TE-induced apoptosis. These data indicate that simultaneous occurrences of Akt inhibition and p38 activation by TE result in the cell death.

Prostaglandin E2 reinforces the activation of Ras signal pathway in lung adenocarcinoma cells via EP3

Prostaglandin E2 (PGE2)-dependent effects on various cell responses are regulated by respective PGE2 receptors (EP1, EP2, EP3, EP4) expressing in target cells. Alveolar type II cell (a main progenitor cell of lung adenocarcinoma) expressed only EP4, while human lung adenocarcinoma cells (A549) expressed EP3 as well as EP4. An antagonistic effect of EP3 against EP4 through the modulation of cyclic AMP level is required for PGE2-mediated activation of Ras signal pathway in A549 cells. These results suggest that the expression of EP3 may be a critical factor for the PGE2-mediated activation of Ras signal pathway in A549 cells.