RRR-alpha-tocopheryl succinate modulation of human promyelocytic leukemia (HL-60) cell proliferation and differentiation

Evaluation of the Antitumor Effect and Immune Response of Micelles Modified with a Polysialic Acid-D-α-Tocopheryl Polyethylene Glycol 1000 Succinate Conjugate

D-α-Tocopheryl polyethylene glycol 1000 succinate (TPGS) has shown potential applications in cancer therapy owing to its attractive properties, including reversal of multi-drug resistance and synergistic effects with antitumor drugs. However, its associated shortcomings cannot be underestimated, including activation of the body's immune response and acceleration of blood clearance of polyethylene glycolylated preparations. Polysialic acid (PSA) is a polysaccharide homopolymer, with the dual function of immune camouflage and tumor targeting. PSA and TPGS conjugates (PSA-TPGS) were synthesized to weaken the immune risks of TPGS. We developed PSA-TPGS and TPGS self-assembled mixed micelles and encapsulated the classical antineoplastic, docetaxel. The particle size of docetaxel-loaded mixed micelles was 16.3 ± 2.0 nm, with entrapment efficiency of 99.0 ± 0.9% and drug-loading efficiency of 3.20 ± 0.03%. Antitumor activity studies revealed that the mixed micelles showed better tumor inhibition than Tween 80 and TPGS micelles. Detection of the accelerated blood clearance (ABC) phenomenon demonstrated that insertion of PSA-TPGS into the micelles weakened the ABC phenomenon induced by TPGS. In summary, PSA-TPGS could be a potential nanocarrier to improve antitumor activity and weaken immune responses.

α-Tocopheryl Succinate Affects Malignant Cell Viability, Proliferation, and Differentiation

The widespread occurrence of malignant tumors motivates great attention to finding and investigating effective new antitumor preparations. Such preparations include compounds of the vitamin E family. Among them, α-tocopheryl succinate (vitamin E succinate (VES)) has the most pronounced antitumor properties. In this review, various targets and mechanisms of the antitumor effect of vitamin E succinate are characterized. It has been shown that VES has multiple intracellular targets and effects, and as a result VES is able to induce apoptosis in tumor cells, inhibit their proliferation, induce differentiation, prevent metastasizing, and inhibit angiogenesis. However, VES has minimal effects on normal cells and tissues. Due to the variety of targets and selectivity of action, VES is a promising agent against malignant neoplasms. More detailed studies in this area can contribute to development of effective and safe chemotherapeutic preparations.

Multifunctional dendrimers modified with alpha-tocopheryl succinate for targeted cancer therapy

Multifunctional generation 5-poly(amidoamine) dendrimers can be used as a platform to conjugate covalently alpha-tocopheryl succinate for targeted cancer therapy.

Antiproliferative and apoptosis-inducing effects of lipophilic vitamins on human melanoma A375 cells in vitro

The effects of six lipophilic vitamins: tretinoin (ATRA), vitamin D(3) (VD(3)), VE, VK(1), VK(3), and VK(5) on cell proliferation and apoptosis in human A375 melanoma cells were investigated. VD(3), VK(3), and VK(5) were found to inhibit cell proliferation significantly at concentration ranges of 10-100 μmol/L (p<0.01), while the other vitamins did not show inhibitory effects at 100 μmol/L. VK(3) and VK(5) showed the strongest effects with IC(50) values of less than 10 μmol/L. Dacarbazine slightly inhibited the proliferation of A375 cells at a concentration range of 25-100 μmol/L, but the effects were not statistically significant. VK(3) and VK(5) increased annexin-V positive apoptotic cells, as well as activating caspase-3, in A375 cells. Our findings showed that VD(3), VK(3,) and VK(5) inhibited the growth of dacarbazine resistant human melanoma cells, while ATRA, VE, and VK(1) had little effect on the cell growth. The effects of VK(3) and VK(5) were observed at concentrations lower than 10 μmol/L, which are suggested to have resulted from apoptosis-induction in the melanoma cells.

Augmented suppression of androgen receptor signaling by a combination of alpha-tocopheryl succinate and methylseleninic acid

BACKGROUND

Previous reports showed that alpha-tocopheryl succinate (alphaTS) and methylseleninic acid (MSA) independently reduce the abundance of androgen receptor (AR) in prostate cancer cells. The response to MSA happens quickly, whereas the response to alphaTS takes much longer. The present study was designed to investigate whether a combination of alphaTS and MSA would produce an additive or a greater than additive effect in suppressing AR level, AR transactivation, and prostate-specific antigen (PSA).

METHODS

LNCaP cells were treated with alphaTS alone for 31 hours, MSA alone for 3 hours, or alphaTS first for 28 hours and alphaTS/MSA together for the last 3 hours. AR and PSA mRNA levels were quantitated by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). AR transactivation was determined by the ARE-luciferase reporter assay. Both cellular and secretory PSA was also measured by the enzyme-linked immunosorbent assay (ELISA) method.

RESULTS

Different doses of alphaTS were evaluated in combination with MSA. Some striking results are highlighted below for alphaTS alone, MSA alone, or alphaTS/MSA (presented in that order). AR mRNA level was depressed by 0%, 20%, or 60%, respectively; AR transactivation was inhibited by 35%, 10%, or 60%, respectively; whereas the PSA mRNA level was decreased by 40%, 60%, or 90%, respectively. Interestingly, secretory PSA was consistently reduced to a greater extent than cellular PSA.

CONCLUSIONS

A combination of alphaTS/MSA produced a greater than additive effect in suppressing AR signaling compared with the single agent. Decreased AR abundance is a major factor, but not necessarily the sole factor, in diminishing the transcriptional activity of AR by alphaTS or MSA.

Growth inhibition and apoptosis-induced effect on human cancer cells of toosendanin, a triterpenoid derivative from chinese traditional medicine

Toosendanin, a triterpenoid derivative isolated from the barks of Melia toosendan Sieb et Zucc, has been used as an anthelmintic vermifuge against ascaris for more than fifty years in China. In the present study, we investigated the growth inhibition and apoptosis-induced effect of toosendanin on human cancer cells. The result showed that toosendanin significantly suppressed the proliferation of tested human cancer cell lines. The IC(50) values were less than 1.7 x 10(-7) M and U937 was the most sensitive cell line with a IC(50) of 5.4 x 10(-9) M. Flow cytometric analysis revealed that treatment of U937 cells with toosendanin resulted in a dose- and time-dependent accumulation of cells in the S phase with a concomitant decrease in cells processing to G(0)/G(1) phase. The growth inhibition of U937 cells after exposure to toosendanin was subsequently associated with the induction of apoptosis, as evidence by the typical condensed and fragmented nuclei, DNA fragmentation, and exposure of phosphatidylserine on the outer leaflet of plasma membrane. All these results indicated that toosendanin could serve as a potential candidate for anticancer drug.

Vitamin E succinate suppresses prostate tumor growth by inducing apoptosis

Prostate cancer is a major cause of cancer death and morbidity in western countries. However, because of its intrinsic nature of chemoresistance, there is only limited systemic therapy available for the patients. Vitamin E (VE) has been under intensive study as a chemopreventive agent for various types of cancers. Preclinical studies suggest that vitamin E succinate (VES) is the most effective antitumor analogue of VE, yet there are scarce studies of VES in prostate cancer. In this study, we investigated the effects of VES on a panel of prostate cancer cells, and a xenograft model of prostate cancer. Our results indicate that VES significantly inhibited proliferation and induced apoptosis of prostate cancer cell lines in a dose and time dependent manner. The results of microarray analysis followed by real-time RT-PCR and inhibitor analyses indicated that the VES-induced apoptosis is mediated by caspase-4 in prostate tumor cells. In our animal model of prostate cancer in SCID mouse, daily injection of VES significantly suppressed tumor growth as well as lung metastases. These results suggest a potential therapeutic utility of VES for patients with prostate cancer.

Chemopreventive effect of dietary d-alpha-tocopheryl succinate supplementation on precancer colon aberrant crypt formation and vitamin E analogue levels in young and old rats

This study examined the effects of dietary d-alpha-tocopheryl succinate (TS) in female rats, 20 mo (OLD) or 2 mo (YNG) of age, on azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) and tissue distribution of d-alpha-tocopherol (alphaT), d-gamma-tocopherol (gammaT), and alphaTS. Rats were fed a commercial rodent chow supplemented with or without 1 (YNG) or 2 (OLD) g alphaTS/kg diet for 1 week prior to ip administration of AOM to induce colon ACF. The animals were sacrificed after 49 days of exposure. The results showed that OLD rats had significantly fewer ACF than YNG animals, and the percent body fat and serum triglycerides were significantly higher in the OLD group compared with the YNG. However, only OLD animals receiving alphaTS had significantly reduced numbers of larger ACF and significantly higher levels of colonic alphaT, gammaT, and alphaTS. These data support previous studies demonstrating that dietary alphaTS administration is protective against intestinal cancer. Also, this is the first study to show that alphaTS accumulates in most tissues following dietary exposure. We hypothesize that increased colon accumulation of fat-soluble vitamin E compounds and subsequent chemoprevention may be related to greater percent body fat and serum triglycerides in OLD animals receiving dietary TS.

Pro-apoptotic mechanisms of action of a novel vitamin E analog (alpha-TEA) and a naturally occurring form of vitamin E (delta-tocotrienol) in MDA-MB-435 human breast cancer cells

Vitamin E derivative, RRR-alpha-tocopheryl succinate (vitamin E succinate, VES), is a potent pro-apoptotic agent, inducing apoptosis by restoring both transforming growth factor-beta (TGF-beta) and Fas (CD95) apoptotic signaling pathways that contribute to the activation of c-Jun N-terminal kinase (JNK)-mediated apoptosis. Objectives of these studies were to characterize signaling events involved in the pro-apoptotic actions of a naturally occurring form of vitamin E, delta-tocotrienol, and a novel vitamin E analog, alpha-tocopherol ether acetic acid analog [alpha-TEA; 2,5,7,8-tetramethyl-2R-(4R,8R,12-trimethyltridecyl)chroman-6-yloxyacetic acid]. Like VES, alpha-TEA and delta-tocotrienol induced estrogen-nonresponsive MDA-MB-435 and estrogen-responsive MCF-7 human breast cancer cells to undergo high levels of apoptosis in a concentration- and time-dependent fashion. Like VES, the two compounds induced either no or lower levels of apoptosis in normal human mammary epithelial cells and immortalized but nontumorigenic human MCF-10A cells. The pro-apoptotic mechanisms triggered by the structurally distinct alpha-TEA and delta-tocotrienol were identical to those previously reported for VES, that is, alpha-TEA- and delta-tocotrienol-induced apoptosis involved up-regulation of TGF-beta receptor II expression and TGF-beta-, Fas- and JNK-signaling pathways. These data provide a better understanding of the anticancer actions of a dietary form of vitamin E (delta-tocotrienol) and a novel nonhydrolyzable vitamin E analog (alpha-TEA).

Comparison of vitamin E derivatives alpha-TEA and VES in reduction of mouse mammary tumor burden and metastasis

A novel nonhydrolyzable ether derivative of RRR-alpha-tocopherol, RRR-alpha-tocopherol ether acetic acid analog [2,5,7,8-tetramethyl-2R-(4R,8R,12-trimethyltridecyl)chroman-6-yloxyacetic acid (alpha-TEA)], and a hydrolyzable ester derivative RRR-alpha-tocopheryl succinate (vitamin E succinate; VES) inhibited BALB/c mouse 66cl-4-GFP mammary tumor cell growth in vitro and in vivo. Treatment of 66cl-4-GFP cells in culture with alpha-TEA or VES induced dose-dependent DNA synthesis arrest and apoptosis and inhibited colony formation. Liposomal formulations of alpha-TEA delivered orally or by aerosol significantly reduced subcutaneous 66cl-4-GFP tumor burden and metastasis to lung and lymph nodes. Liposomal formulations of VES delivered by aerosol significantly reduced tumor burden and lung metastasis, but not lymph node metastasis. Unlike alpha-TEA, VES was ineffective in reducing tumor burden and metastasis to lungs and lymph nodes when administered orally. Analyses of tumor sections showed that alpha-TEA delivered by either method significantly reduced tumor cell proliferation as measured by Ki67, and increased apoptosis as measured by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL), whereas VES delivered by aerosol reduced tumor cell proliferation and increased apoptosis, but not significantly. In summary, the nonhydrolyzable ether vitamin E derivative alpha-TEA was effective in reducing tumor burden and metastasis when delivered either by aerosol or orally, whereas the hydrolyzable ester vitamin E derivative VES was effective only when delivered by aerosol.

Differential response of human ovarian cancer cells to induction of apoptosis by vitamin E Succinate and vitamin E analogue, alpha-TEA

A vitamin E derivative, vitamin E succinate (VES; RRR-alpha-tocopheryl succinate), and a vitamin E analogue, 2,5,7,8-tetramethyl-2R-(4R,8R,12-trimethyltridecyl)chroman-6-yloxy acetic acid (alpha-TEA), induce human breast, prostate, colon, lung, cervical, and endometrial tumor cells in culture to undergo apoptosis but not normal human mammary epithelial cells, immortalized, nontumorigenic breast cells, or normal human prostate epithelial cells. Human ovarian and cervical cancer cell lines are exceptions, with alpha-TEA exhibiting greater proapoptotic effects. Although both VES and alpha-TEA can induce A2780 and subline A2780/cp70 ovarian cancer cells to undergo DNA synthesis arrest within 24 h of treatment, only alpha-TEA is an effective inducer of apoptosis. VES or alpha-TEA treatment of cp70 cells with 5, 10, or 20 microg/ml for 3 days induced 5, 6, and 19% versus 9, 36, and 71% apoptosis, respectively. Colony formation data provide additional evidence that cp70 cells are more sensitive to growth inhibition by alpha-TEA than VES. Differences in stability of the ester-linked succinate moiety of VES versus the ether-linked acetic acid moiety of alpha-TEA were demonstrated by high-performance liquid chromatography analyses that showed alpha-TEA to remain intact, whereas VES was hydrolyzed to the free phenol, RRR-alpha-tocopherol. Pretreatment of cp70 cells with bis-(p-nitrophenyl) phosphate, an esterase inhibitor, before VES treatment, resulted in increased levels of intact VES and apoptosis. Taken together, these data show alpha-TEA to be a potent and stable proapoptotic agent for human ovarian tumor cells and suggest that endogenous ovarian esterases can hydrolyze the succinate moiety of VES, yielding RRR-alpha-tocopherol, an ineffective apoptotic-inducing agent.

Toosendanin induces outgrowth of neuronal processes and apoptosis in PC12 cells

In the present study, the effects of toosendanin on cell differentiation and apoptosis were investigated in PC12 cells. The results showed that after 24-48 h of culture in a medium containing toosendanin (approximately 1-10x10(-7) M), cell differentiation and outgrowth of neuronal processes were promoted. Combined treatment with toosendanin and a calcium channel blocker, nifedipine or omega-conotoxin GVIA, resulted in a significant inhibition of the toosendanin-induced effects. Pretreatment of PC12 cells with BAPTA-AM also inhibited the toosendanin-induced effects; however, these effects were not inhibited by pertussis toxin and H-7 in the medium. Toosendanin also induced cell apoptosis. Based on the DNA content determined by flow cytometric analysis, the number of apoptotic cells significantly increased when the incubation time in the toosendanin-containing medium was lasted up to 72 h. Toosendanin at a higher concentration (> or =1 x 10(-6) M) caused cell death while it had no effect on cell division at concentrations lower than 1 x 10(-7) M.

Role of extracellular signal-regulated kinase pathway in RRR-alpha-tocopheryl succinate-induced differentiation of human MDA-MB-435 breast cancer cells

RRR-alpha-tocopheryl succinate (vitamin E succinate, VES) induces differentiation of human breast cancer cells. Previous studies ruled out transforming growth factor-beta and c-jun N-terminal kinase involvement in VES-induced differentiation but implicated extracellular signal-regulated kinases (ERKs). Here we show that dominant-negative mutants of either mitogen-activated protein kinase kinase (MEK) 1 or ERK1 blocked VES-induced differentiation of MDA-MB-435 cells, as measured by induction of cytokeratin 18 and p21 (Waf1/Cip1) proteins. Blockage of c-jun protein expression using c-jun antisense oligonucleotides or expression of an inducible dominant-negative c-jun mutant protein inhibited VES-induced differentiation. Elevated expression of wild-type c-jun alone was sufficient to induce cellular differentiation. A role for p21 (Waf1/Cip1) is implicated, in that p21 antisense oligomers blocked VES-induced differentiation. In summary, MEK1, ERK1, the transcription factor c-jun, and the cyclin-dependent kinase inhibitor p21 (Waf1/Cip1) play a part in VES-induced differentiation of human MDA-MB-435 breast cancer cells.

Activation of PKC but not of ERK is required for vitamin E-succinate-induced apoptosis of HL-60 cells

Vitamin E-succinate (VES) induced HL-60 human leukemia cells to undergo apoptosis. Treatment with VES induced membrane translocation of Fas; cleavages of caspase-3, PARP, and lamin B; hypophosphorylation of retinoblastoma protein; and increase of p21(WAF1) protein level. During the induction of apoptosis, activity of PKC was gradually increased with downregulation of VES-induced ERK activity and accompanied by activation of caspase-3. Inhibition of PKC by GF109203X blocked VES-mediated membrane translocation of PKC-alpha and cleavage of caspase-3 cascade, resulting in prevention of VES-induced apoptosis. On the contrary, PKC activation by cotreatment with LPC or thapsigargin and VES synergistically increased VES-mediated apoptosis. However, inhibition of ERK activity by PD98059 showed no significant effect on VES-induced PKC activity and apoptosis. Taken together, our data suggest that VES induces activation of PKC and PKC-dependent hypophosphorylation of retinoblastoma protein, which results in induction of apoptosis, and that VES-induced early activation of ERK and ERK-dependent induction of p21(WAF1) are not required for apoptosis.

Inhibitory effects of RRR-alpha-tocopheryl succinate on benzo(a)pyrene (B(a)P)-induced forestomach carcinogenesis in female mice

AIM

To study the inhibitory effects of VES (RRR-alpha-tocopheryl Succinate, VES),a derivative of natural Vitamin E, on benzo(a)pyrene(B(a)P)-induced forestomach tumor in female mice.

METHODS

The model of B(a)P-induced forestomach tumor was established according to the methods of Wattenberg with slight modify-cations. One hundred and eighty female mice (6 weeks old) were divided into six groups equally; negative control (Succinic acid), vehicle control (Succinate+B(a)P),positive control(B(a)P), high VES(2.5 g/kg.b.w+B(a)P), low VES(1.25 g/kg.b.w+B(a)P)ig as well as VES by ip (20 mg/kg.b.w+B(a)P). Except the negative control group, the mice were administrated with B(a)P ig. and corresponding treatments for 4 weeks to study the anti-carcinogenetic effect of VES during the initiation period. The experiment lasted 29 weeks, in which the inhibitory effects of VES both on tumor incidence and tumor size were tested.

RESULTS

The models of B(a)P-induced forestomach tumor in female mice were established successfully. Some were cauliflower-like, others looked like papilla, even a few were formed into the ulcer cavities. VES at 1.25 g/kg.b.w, 2.5 g/kg.b.w. by ig and 20 mg/kg.b.w. via ip could decrease the number of tumors per mouse (1.7 plus minus 0.41, 1.6 plus minus 0.34 and 1.1 +/- 0.43), being lower than that of B(a)P group (5.4 +/- 0.32, P<0.05). The tumor incidence was inhibited by 18.2%, 23.1% and 50.0%. VES at 1.25 g/kg.b.w., 2.5 g/kg.b.w. by ig and 20 mg/kg.b.w. via ip reduced the total volume of tumors per mouse (54.8 +/- 8.84, 28.4 8 +/- 8.32 and 23.9 8 +/- 16.05), being significantly lower than that of B(a)P group (150.2 8 +/- 20.93, P < 0.01). The inhibitory rates were 63.5%, 81.1% and 84.1%, respectively.

CONCLUSION

VES has inhibitory effects on B(a)P-induced forestomach carcinogenesis in female mice, especially by ip and it may be a potential anti-cancer agent in vivo.

Vitamin E succinate promotes breast cancer tumor dormancy

BACKGROUND

Vitamin E succinate (VES) is the most potent antitumor analogue of vitamin E. Despite many reports of VES's antitumor activity in vitro, there is little information about its antitumor effects in vivo.

MATERIALS AND METHODS

We investigated the effect of VES on the growth of human breast cancer cells in vitro and in vivo.

RESULTS

VES decreased cell viability in MDA-MB-231 and MCF-7 human breast cancer cells. Although VES increased apoptosis in MDA-MB-231 cells, it had no effect on apoptosis in MCF-7 cells. The inhibitory effect of VES on cell growth was specific for the intact molecule because a markedly reduced effect was noted when either vitamin E or succinic acid was administered alone. VES inhibited the growth of MDA-MB-231 cells in nude mice. Also, VES was found to inhibit vascular endothelial growth factor (VEGF) gene expression in MDA-MB-231 cells.

CONCLUSIONS

VES inhibits the growth of breast cancer cells in vitro and in vivo. This is the first report of VES inhibition of established tumor growth in vivo. The mechanism of VES's in vivo effects may involve inhibition of tumor angiogenesis since VES inhibits VEGF gene expression.

Vitamin E succinate induces apoptosis in human prostate cancer cells: role for Fas in vitamin E succinate-triggered apoptosis

The apoptosis-triggering properties of vitamin E succinate (VES, RRR-alpha-tocopheryl succinate) for human LNCaP and PC-3 prostate carcinoma cells and normal PrEC human prostate epithelial cells were investigated. LNCaP and PC-3 cells were sensitive to VES-induced apoptosis, with 100% and 60% of cells undergoing apoptosis after three days of treatment with 10 micrograms of VES/ml, respectively. PrEC cells were resistant to VES-induced apoptosis. Treatment of prostate cells with agonistic anti-Fas antibody triggered apoptosis in approximately 50% of PC-3 cells within 48 hours, whereas LNCaP and PrEC cells were resistant. Prostate cells simultaneously treated with VES and agonistic anti-Fas antibodies revealed 1) no effect on PrEC cells, 2) an additive effect on Fas-sensitive PC-3 cells, and 3) a synergistic effect on LNCaP cells. VES treatment of LNCaP cells caused depletion of cytosolic 43-kDa Fas, enhanced membrane levels of 43-kDa Fas, and induced Fas sensitivity. PC-3 cells expressed high levels of membrane 43-kDa Fas that were enhanced by VES treatments. Fas ligand expression by LNCaP cells was enhanced by VES treatments. In summary, VES triggers apoptosis in human prostate carcinoma cells but not normal prostate cells in vitro, and VES modulates Fas signaling.

Tocotrienol: a review of its therapeutic potential

OBJECTIVES

To summarize new knowledge surrounding the physiological activity of tocotrienol, a natural analogue of tocopherol.

RESULTS

The biological activity of vitamin E has generally been associated with its well-defined antioxidant property, specifically against lipid peroxidation in biological membranes. In the vitamin E group, alpha-tocopherol is considered to be the most active form. However, recent research has suggested tocotrienol to be a better antioxidant. Moreover, tocotrienol has been shown to possess novel hypocholesterolemic effects together with an ability to reduce the atherogenic apolipoprotein B and lipoprotein(a) plasma levels. In addition, tocotrienol has been suggested to have an anti-thrombotic and anti-tumor effect indicating that tocotrienol may serve as an effective agent in the prevention and/or treatment of cardiovascular disease and cancer.

CONCLUSION

The physiological activities of tocotrienol suggest it to be superior than alpha-tocopherol in many situations. Hence, the role of tocotrienol in the prevention of cardiovascular disease and cancer may have significant clinical implications. Additional studies on its mechanism of action, as well as, long-term intervention studies, are needed to clarify its function. From the pharmacological point-of-view, the current formulation of vitamin E supplements, which is comprised mainly of alpha-tocopherol, may be questionable.

Sensitive method for measuring tissue alpha-tocopherol and alpha-tocopheryloxybutyric acid by high-performance liquid chromatography with fluorometric detection

The nonhydrolysable tocopherol ether analog, d-alpha-tocopheryloxybutyric acid (TSE), and its tocopherol ester counterpart, d-alpha-tocopheryl hemisuccinate (TS), have been shown to possess anti-tumor activity. In the present study, a sensitive high-performance liquid chromatography (HPLC) method using fluorometric detection is described for the simultaneous determination of TSE and alpha-T in biological specimens. Maximal sensitivity for the measurement of TSE and alpha-T was observed with the wavelengths, 210 nm excitation and 300 nm emission. Using an internal standard (I.S.) method, the amount of these tocopherol compounds was determined in standards, liver homogenates isolated from rats administered TSE-tris salt or vehicle (saline) and in HL-60 human leukaemia cells incubated with TSE-tris salt or saline. Treatment with TSE resulted in the significant accumulation of TSE, but not alpha-T, in the liver and HL-60 cells.

Production of inducible nitric oxide is required for monocytic differentiation of U937 cells induced by vitamin E-succinate

Many putative differentiating agents arrest cell growth prior to progression of the cell through differentiation. Vitamin E-succinate is known to be a potent modulator of haematopoietic differentiation as well as an inhibitor of cell growth in vitro and in vivo. In this study, we examined whether vitamin E-succinate could modulate the monocytic differentiation of U937 human monoblasts. Treatment with vitamin E-succinate for 1–4 days inhibited the proliferation of U937 cells. Vitamin E-succinate also induced monocytic differentiation as indicated by the increase in nitro blue tetrazolium reduction activity, and the expression of monocyte specific cell surface antigen, CD11c, and integrins alpha5 and beta1. The monocytic differentiation of U937 cells was also induced when the cells were cultured in fibronectin-coated wells. Monocytic differentiation was enhanced when the cells were treated with both vitamin E-succinate and fibronectin, suggesting that vitamin E-succinate and fibronectin synergistically act on monocytic differentiation of U937 cells. During monocytic differentiation of U937 cells induced by vitamin E-succinate and/or fibronectin, nitric oxide was detected in supernatants. The production of nitric oxide was not detected when monocytic differentiation of U937 cells was induced by phorbol-12 myristate 13-acetate, a well known inducer of macrophage-like cell differentiation. Vitamin E-succinate and/or fibronectin induced monocytic differentiation was blocked by the treatment of nitric oxide synthase inhibitor, N-G-monomethyl-L-arginine. In contrast, treatment of cells with sodium nitroprusside, a chemical nitric oxide donor, stimulated monocytic differentiation of U937 cells at an early time point. Taken together, these results suggest that nitric oxide is an important intermediator at an early stage of vitamin E-succinate- and/or fibronectin-induced monocytic differentiation of U937 cells.

Etorphine inhibits cell growth and induces apoptosis in SK-N-SH cells: involvement of pertussis toxin-sensitive G proteins

Opiates have been used extensively in the treatment of pain but with the severe side effect of addiction, which is believed to be related to opiates' direct (primary) or indirect (secondary) neurotoxicity. In this study, the effects of opioids on cell growth and apoptosis have been examined in human neuroblastoma cell line SK-N-SH. Etorphine, a wide-spectrum and potent agonist of opioid receptors, was found to significantly inhibit cell growth and to induce apoptosis. The inhibitory and apoptotic activities of etorphine followed a dose- and time-dependent manner. The more specific agonists of opioid receptors such as morphine, [D-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (DAGO), [D-Pen2, D-Pen5]-enkephalin (DPDPE), dynorphin A and nociceptin/orphanin FQ did not show similar toxic activities under the same conditions. In addition, the effects of etorphine could not be blocked by the opioid receptor antagonist naloxone, suggesting that the effects of etorphine might not be mediated by a classical opioid receptor. However, pretreatment of SK-N-SH cells with pertussis toxin (PTX) blocked the inhibition of cell growth and apoptosis induced by etorphine, indicating the involvement of PTX-sensitive G proteins in the processes. It was also shown that etorphine-induced apoptosis was prevented by actinomycin D (AD) and interleukin-1beta converting enzyme inhibitor I. Interestingly, etorphine was similarly potent to inhibit growth of pheochromocytoma (PC12) cells but less effective in SH-SY5Y neuroblastoma cells and C6 glioma cells. We propose that inhibition of cell growth and induction of apoptosis may be one mechanism of opioid neurotoxicity.

Tretinoin tocoferil as a possible differentiation-inducing agent against myelomonocytic leukemia

Tretinoin tocoferil is an alpha-tocopherol ester of all-trans retinoic acid (ATRA) and safely used to treat skin ulcers. Tretinoin tocoferil stimulates the formation of granulation tissue in the ulcer, and enhances the migration of guinea pig macrophages and stimulates the proliferation of human skin fibroblasts. These effects are different from those of either ATRA or alpha-tocopherol. Tretinoin tocoferil induces the granulocytic differentiation of human promyelocytic leukemia HL-60 cells, and more than additively enhances cellular differentiation induced by sub-optimal concentrations of ATRA. Tretinoin tocoferil and ATRA synergistically inhibit the proliferation of HL-60 cells, suggesting that tretinoin tocoferil acts differently than ATRA on leukemia cells. Tretinoin tocoferil also enhances the differentiation of HL-60 cells induced by dimethyl sulfoxide, phorbol ester and 1alpha,25-dihydroxyvitamin D3(VD3). Tretinoin tocoferil and VD3 synergistically inhibit the proliferation and induce the differentiation of other myelomonocytic leukemia cells. Toxicity tests in animal models have shown that tretinoin tocoferil is at least 150 times less toxic than ATRA and does not induce teratogenesis. Therefore, the combination of tretinoin tocoferil and VD3 may be useful for treating myelomonocytic leukemia.

Inhibition of growth in oral squamous carcinoma cells by cyclopentenone prostaglandins: comparison with chemotherapeutic agents

Four cyclopentenone prostaglandins (CPPGs) and PGE2 caused significant dose-dependent inhibition in growth of human oral squamous carcinoma cells (SCC-15). The rank order of their potency was PGJ2>PGA1>16, 16-dimethyl PGA1>PGA2>PGE2. In a follow-up experiment it was found that the mean per cent inhibition in cell growth by PGJ2 and delta12-PGJ2 at 10(-5) M was 61.22 and 63.81, while that of 5-fluorouracil and methotrexate was 36.67 and 38.86, respectively. delta12-PGJ2 and PGJ2 induced significant dose-dependent inhibition in nuclear DNA synthesis (i.e. cell proliferation). Combining vitamin E succinate with lower concentrations of CPPGs enhanced significantly their inhibitory effect on nuclear DNA synthesis of cancer cells.

Growth inhibition of MCF-7 and MCF-10A human breast cells by alpha-tocopheryl hemisuccinate, cholesteryl hemisuccinate and their ether analogs

The growth inhibitory properties of alpha-tocopheryl hemisuccinate (vitamin E succinate) and related compounds were examined in MCF-7 human breast tumor cells and MCF-10A normal-like human breast cells since they have been suggested to be an effective antitumor compound. The data showed that both alpha-tocopherol hemisuccinate and a structurally-similar compound, cholesteryl hemisuccinate, inhibited the growth of MCF-7 and MCF-10A cells, while alpha-tocopherol, cholesterol, cholesteryl sulfate and Tris succinate had little effect on cell growth. The ether analogs of the succinate esters, alpha-tocopheryloxybutyric acid and cholesteryloxybutyric acid, also inhibited growth of MCF-7 and MCF-10A cells, indicating that hydrolysis of the succinate esters by esterases is not required for the antiproliferative effects. The antiproliferative effects of these succinate esters and ethers may be related to their physiochemical properties that allow incorporation into cell membranes.

Evidence for role of transforming growth factor-beta in RRR-alpha-tocopheryl succinate-induced apoptosis of human MDA-MB-435 breast cancer cells

MDA-MB-435 human breast cancer cells treated with 10 micrograms/ml of RRR-alpha-tocopheryl succinate (vitamin E succinate, VES) for one, two, three, and four days exhibit 9%, 19%, 51%, and 73% apoptotic cells, respectively. Likewise, cells cultured for one, two, and three days with conditioned media (CM) obtained from MDA-MB-435 cells treated with VES exhibit 10%, 36%, and 74% apoptosis, respectively. A quantitative luciferase-based assay showed CM from VES-treated cells collected at 24 and 48 hours after treatment initiation to contain 75 and 32 pg of active transforming growth factor-beta (TGF-beta), respectively, per 10(6) cells. Although purified TGF-beta 1 is not an effective apoptotic agent for MDA-MD-435 cells, cotreatment of the cells for three days with suboptimal levels of VES (2.5 and 5 micrograms/ml) + 10 ng/ml of purified TGF-beta 1 enhanced apoptosis by 66% and 68%, respectively. Interference of the TGF-beta-signaling pathway by transient transfection of MDA-MB-435 cells with antisense oligomers to TGF-beta type II receptor (TGF-beta R-II) blocked VES-induced apoptosis. Likewise, addition of neutralizing antibodies to TGF-beta 1 or to all three mammalian isoforms of TGF-beta (TGF-beta 1, -beta 2, -beta 3) blocked VES- and CM-induced apoptosis. Furthermore, inhibitors of TGF-beta conversion from an inactive latent form to a biologically active form inhibited VES-induced apoptosis. In summary, the ability to reduce apoptosis by blocking TGF-beta or the TGF-beta receptor-signaling pathway with antisense oligomers or ligand-neutralizing antibodies or prevention of activation of TGF-beta indicates a role for TGF-beta signaling in VES-induced apoptosis.

RRR-alpha-tocopheryl succinate inhibits EL4 thymic lymphoma cell growth by inducing apoptosis and DNA synthesis arrest

RRR-alpha-tocopheryl succinate (vitamin E succinate, VES) treatment of murine EL4 T lymphoma cells induced the cells to undergo apoptosis. After 48 hours of VES treatment at 20 micrograms/ml, 95% of cells were apoptotic. Evidence for the induction of apoptosis by VES treatments is based on staining of DNA for detection of chromatin condensation/fragmentation, two-color flow-cytometric analyses of DNA content, and end-labeled DNA and electrophoretic analyses for detection of DNA ladder formation. VES-treated EL4 cells were blocked in the G1 cell cycle phase; however, apoptotic cells came from all cell cycle phases. Analyses of mRNA expression of genes involved in apoptosis revealed decreased c-myc and increased bcl-2, c-fos, and c-jun mRNAs within three to six hours after treatment. Western analyses showed increased c-Jun, c-Fos, and Bcl-2 protein levels. Electrophoretic mobility shift assays showed increased AP-1 binding at 6, 12, and 24 hours after treatment and decreased c-Myc binding after 12 and 24 hours of VES treatment. Treatments of EL4 cells with VES+RRR-alpha-to-copherol reduced apoptosis without effecting DNA synthesis arrest. Treatments of EL4 cells with VES+rac-6-hydroxyl-2, 5,7,8-tetramethyl-chroman-2-carboxylic acid, butylated hydroxytoluene, or butylated hydroxyanisole had no effect on apoptosis or DNA synthesis arrest caused by VES treatments. Analyses of bcl-2, c-myc, c-jun, and c-fos mRNA levels in cells receiving VES + RRR-alpha-tocopherol treatments showed no change from cells receiving VES treatments alone, implying that these changes are correlated with VES treatments but are not causal for apoptosis. However, treatments with VES + RRR-alpha-tocopherol decreased AP-1 binding to consensus DNA oligomer, suggesting AP-1 involvement in apoptosis induced by VES treatments.

RRR-alpha-tocopheryl succinate induces apoptosis in avian retrovirus-transformed lymphoid cells

The RRR-alpha-tocopheryl succinate form of vitamin E [vitamin E succinate (VES)] inhibits the proliferation of avian reticuloendotheliosis virus-transformed RECC-UTC4-1 (C4-1) lymphoblastoid cells in a dose-dependent manner, blocks the cells in the G2/M cell cycle phase, and induces the cells to undergo apoptosis. Apoptosis was documented by demonstrating changes that are characteristic of this type of cell death, including morphological analyses of chromatin condensation by 4',6-diamidine-2'-phenylindole dihydrochloride (DAPI) staining using scanning confocal and traditional fluorescent microscopy; flow cytometry analyses of propidium iodide-labeled DNA showing fragmented DNA as a pre-G1 peak; two-color flow cytometry analyses of intact cells labeled first by the TUNEL procedure (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end-labeled DNA stained with fluorescein isothiocyanate-labeled avidin) and then by propidium iodide demonstrating fragmented DNA; and electrophoresis of DNA showing a DNA ladder created by internucleosomal DNA fragmentation. The percentage of apoptotic cells was determined by DAPI staining and showed 11%, 27%, and 49% of cells to be apoptotic after treatment with 10 micrograms/ml VES for one, two, and three days, respectively. Analyses of mRNA levels of genes that have been implicated in the apoptotic process, namely, bcl-2, c-myc, and c-jun, revealed no change in bcl-2, decreases in c-myc mRNA levels after 36 hours of treatment, and increases in c-jun mRNA levels within four hours after treatment. Western immunoblotting analyses of protein levels for the transcription factors c-Myc and c-Jun showed normal levels of c-Myc at early time points and decreased levels at 24 and 48 hours after treatment. c-Jun increased as early as 6 hours after treatment and returned to lower (yet still elevated over control) levels by 48 hours. To determine possible functional consequences of increased c-Jun expression, gel electrophoretic mobility assays were conducted that showed increased AP-1 binding at 24 and 48 hours after treatment. These data show that VES induces apoptosis in reticuloendotheliosis virus-transformed lymphoid cells and suggest that decreases of c-Myc protein and increases of c-Jun protein and DNA binding capacity may be playing a role in VES-mediated events leading to apoptosis in this cell type.

Modulation of murine EL-4 thymic lymphoma cell proliferation and cytokine production by vitamin E succinate

RRR-alpha-tocopheryl succinate (VES) was studied for effects on murine EL-4 cell proliferation and production of interleukin-2 (IL-2) and transforming growth factor-beta (TGF-beta). VES was biphasic in its actions: 0.1 microgram/ml enhanced EL-4 cell proliferation, whereas 10-20 microgram/ml inhibited cellular proliferation. Cell-conditioned media (CM) from EL-4 cells treated with 0.2 ng/ml phorbol myristate acetate (PMA) + 0.1 microgram/ml VES contained increased amounts of IL-2, as determined by the murine cytotoxic T cell IL-2-dependent CTLL-2 bioassay. VES at 0.1 microgram/ml or 0.1 microgram/ml VES + 0.2 ng/ml PMA induced the expression of IL-2 mRNA by EL-4 cells three to nine hours after treatment. CM from EL-4 cells treated with VES at 10-20 microgram/ml exhibited potent antiproliferative activity when tested in the TGF-beta-responsive mink lung cell (Mv1Lu) bioassay and showed reduced inhibitory effects when tested on TGF-beta receptor-negative mink lung (DRA-27) cells. CM from control-treated EL-4 cells exhibited no antiproliferative activity. The VES-induced antiproliferative activity was characterized as TGF-beta by neutralization analyses and immunoprecipitation of metabolically labeled proteins with TGF-beta-specific reagents. VES treatment of EL-4 cells had no effect on TGF-beta 1 mRNA expression while downregulating TGF-beta 3 mRNA expression. In summary, these studies showed that 0.1 microgram/ml VES enhanced cellular proliferation, in part, via increased IL-2 production, whereas 10-20 micrograms/ml VES inhibited cellular proliferation, in part, via the secretion of biologically active TGF-beta.

RRR-alpha-tocopheryl succinate enhances TGF-beta 1, -beta 2, and -beta 3 and TGF-beta R-II expression by human MDA-MB-435 breast cancer cells

The proliferation of MDA-MB-435 human breast cancer cells was inhibited by RRR-alpha-tocopheryl succinate (vitamin E succinate, VES). Conditioned media (CM) from VES growth-inhibited cells contained potent antiproliferative activity, part of which is contributed by transforming growth factor-beta (TGF-beta) isoforms. Antibody neutralization analysis, employing TGF-beta isoform-specific antibody reagents, showed that TGF-beta 1, -beta 2, and -beta 3 were present in the CM from VES-treated cells. Culturing MDA-MB-435 cells with VES did not alter the levels of constitutively expressed 2.4-kb TGF-beta 1, 3.0- and 4.0-kb TGF-beta 2, or 1.2- and 3.5-kb TGF-beta 3 mRNA transcripts. Inhibition of DNA synthesis by MDA-MB-435 cells was increased by combinations of suboptimal levels of VES and purified TGF-beta 1. VES-treated MDA-MB-435 cells exhibited enhanced binding of radiolabeled TGF-beta 1, and Western immunoblotting analyses showed that VES treatment enhanced TGF-beta type II receptor protein expression. TGF-beta type I receptor protein levels were not modified by VES treatments. Although the mRNA transcript for the 5.5-kb TGF-beta type II receptor was upregulated after four hours of treatment with VES, this treatment did not modify the 6.5-kb TGF-beta type I or the 6.5-kb TGF-beta type II receptor mRNAs. Results demonstrate that biologically active TGF-beta 1, -beta 2, -beta 3 and levels of TGF-beta type II receptor expressed by human breast cancer cells are enhanced by VES treatment.

RRR-alpha-tocopheryl succinate inhibits DNA synthesis and enhances the production and secretion of biologically active transforming growth factor-beta by avian retrovirus-transformed lymphoid cells

The RRR-alpha-tocopheryl succinate form of vitamin E, referred to as vitamin E succinate (VES), inhibits the proliferation of avian reticuloendotheliosis virus-transformed RECC-UTC4-1 (C4-1) lymphoblastoid cells in a dose-dependent manner in vitro. Analyses of conditioned medium (CM) from VES growth-inhibited cells revealed a potent antiproliferative activity. Characterization of the antiproliferative activity as transforming growth factor-beta (TGF-beta) was established by 1) growth inhibition of TGF-beta-responsive Mv1Lu mink lung and murine CTLL-2 cell lines, 2) a combination of physical characteristics including heat stability, acid stability, and Bio-Gel P-60 column chromatography elution profile, 3) neutralization of the antiproliferative activity by antibodies specific for TGF-beta, and 4) immunoprecipitation of metabolically labeled TGF-beta in CM from VES-treated C4-1 cells by use of TGF-beta-specific antibodies. Northern blot analyses of total cellular RNA revealed that VES does not alter the levels of constitutively expressed TGF-beta isoform-specific mRNAs; namely, VES does not alter the levels of the 3.9- and 4.1-kb TGF-beta 2 mRNAs, the 3.0-kb TGF-beta 3 mRNA, or the 2.5-, 2.7-, and 1.7-kb TGF-beta 4 mRNAs. The data show that VES inhibits C4-1 cell proliferation and induces the cells to produce and secrete active forms of TGF-beta, suggesting that one mechanism whereby VES inhibits C4-1 cell proliferation may be via the TGF-beta pathway for cellular growth control.

RRR-alpha-tocopheryl succinate inhibits the proliferation of human prostatic tumor cells with defective cell cycle/differentiation pathways

The RRR-alpha-tocopheryl succinate derivative of vitamin E, referred to as vitamin E succinate (VES), inhibits the proliferation of three metastatic human prostatic cancer cell lines, LNCaP, PC-3, and DU-145. LNCaP is a lymph node-derived androgen-sensitive prostate cell line; these cells are defective for response to transforming growth factor-beta (TGF-beta) but are normal for cell cycle-related tumor suppressor genes: p53 and retinoblastoma (Rb). PC-3 is a bone marrow-derived androgen-insensitive prostate cell line; these cells are defective for both p53 alleles but normal for both Rb alleles. DU-145 is a brain-derived androgen-insensitive prostate cell line; these cells are defective for both p53 and both Rb alleles. VES at 5, 10, and 20 micrograms/ml inhibited DNA synthesis in the three cell lines in a dose-dependent manner. Purified TGF-beta 1 at 1 ng/ml inhibited DNA synthesis of PC-3 cells within 24-72 hours and DU-145 cells at 72 hours but did not inhibit DNA synthesis of LNCaP cells. Previous studies in our laboratory showed that VES growth-inhibited tumor cells secrete biologically active antiproliferative factor TGF-beta s, suggesting that VES's mechanism of growth inhibition may involve the TGF-beta system of growth control.(ABSTRACT TRUNCATED AT 250 WORDS)

Vitamin E succinate induction of HL-60 cell adhesion: a role for fibronectin and a 72-kDa fibronectin-binding molecule

HL-60 cells, growing as single cells in suspension, exhibit marked cell-cell adhesion when treated for 24 hours with 10 micrograms/ml RRR-alpha-tocopheryl succinate, also called vitamin E succinate (VES). VES-induced cell-cell adhesion is dependent on divalent cations and a functional cytoskeleton and is protein mediated. Cell adhesion molecules CD11a/CD18, CD11b/CD18, CD29, and CD54 do not appear to be mediating VES-induced cell adhesion. HL-60 cells treated with VES adhere to fibronectin-coated plastic and secrete elevated levels of fibronectin. A 72-kDa fibronectin-binding membrane molecule was detected on VES-treated HL-60 cells, and antibodies to fibronectin were shown to inhibit VES-induced cell aggregation. VES induction of HL-60 cell-cell adhesion is proposed to result from increased amounts of extracellular fibronectin binding to VES-induced cell surface fibronectin-binding molecules.

RRR-alpha-tocopheryl succinate inhibits proliferation and enhances secretion of transforming growth factor-beta (TGF-beta) by human breast cancer cells

The RRR-alpha-tocopheryl succinate form of vitamin E inhibits the proliferation of estrogen receptor-positive and estrogen receptor-negative human breast cancer cell lines in a dose-dependent manner in vitro. Analyses of cell-conditioned medium from RRR-alpha-tocopheryl succinate growth-inhibited cells revealed the presence of a potent antiproliferative activity. Characterization of the antiproliferative activity as transforming growth factor-beta (TGF-beta) was established by 1) growth inhibition of the TGF-beta-responsive Mv1Lu-CCL-64 mink lung and murine CTLL-2 cell lines, 2) combination of physical characteristics including heat stability, acid stability, and Bio-Gel P-60 column chromatography elution profile, and 3) neutralization of the antiproliferative activity in the conditioned media by antibodies specific for TGF-beta.

RRR-alpha-tocopheryl succinate inhibition of lectin-induced T cell proliferation

The effect of RRR-alpha-tocopheryl succinate (VES) on lectin-induced chicken T cell proliferation was investigated. The T cell mitogens concanavalin A and phytohemagglutinin induce chicken thymic and splenic T cell proliferation. Addition of VES to the in vitro cultures inhibited T cell proliferation in a dose-dependent manner. Addition of VES to spleen cell cultures at different times after mitogen stimulation also suppressed T cell mitogenesis, suggesting that VES is not mediating its antiproliferative effects by interfering with ligand (mitogen)-receptor binding or early ligand-bound receptor-signaling events. Three lines of evidence suggest that the growth-inhibitory properties of VES are unique and may not involve antioxidant properties. 1) Three other forms of vitamin E, dl-alpha-tocopherol, d-alpha-tocopherol, and d-alpha-tocopherol acetate, do not inhibit the proliferation of mitogen-stimulated chicken spleen cells. 2) Spleen cells were treated with an inhibitor of nonspecific esterases to prevent the conversion of VES, which does not exhibit antioxidant properties to d-alpha-tocopherol, a lipid-soluble antioxidant. Treatment of spleen cells with the inhibitor did not affect VES's growth-inhibitory properties. 3) Trolox, a water-soluble vitamin E analogue with potent antioxidant properties and two lipid-soluble antioxidants, butylated hydroxyanisole and butylated hydroxytoluene, did not inhibit mitogen-induced T cell proliferation. Attempts to reverse VES's antiproliferative effects by addition of exogenous interleukin-2 or addition of sodium selenite, an enhancer of interleukin-2 receptors, failed. Acetylsalicylic acid had no effect on VES's inhibition of mitogen-activated T cell proliferation. These studies support the role of VES as a growth inhibitor of lectin-activated normal T cells in chickens.