Enhancement of apoptotic activities on brain cancer cells via the combination of γ-tocotrienol and jerantinine A.

Abubakar IB, Lim KH, Kam TS, Loh HS.

Phytomedicine. 2017 Jul 1;30:74-84. doi: 10.1016/j.phymed.2017.03.004. Epub 2017 Mar 10.

Abstract

BACKGROUND:

γ-Tocotrienol, a vitamin E isomer possesses pronounced in vitro anticancer activities. However, the in vivo potency has been limited by hardly achievable therapeutic levels owing to inefficient high-dose oral delivery which leads to subsequent metabolic degradation. Jerantinine A, an Aspidosperma alkaloid, originally isolated from Tabernaemontana corymbosa, has proved to possess interesting anticancer activities. However, jerantinine A also induces toxicity to non-cancerous cells.

PURPOSE:

We adopted a combinatorial approach with the joint application of γ-tocotrienol and jerantinine A at lower concentrations in order to minimize toxicity towards non-cancerous cells while improving the potency on brain cancer cells.

METHODS:

The antiproliferative potency of individual γ-tocotrienol and jerantinine A as well as combined in low-concentration was firstly evaluated on U87MG cancer and MRC5 normal cells. Morphological changes, DNA damage patterns, cell cycle arrests and the effects of individual and combined low-concentration compounds on microtubules were then investigated. Finally, the potential roles of caspase enzymes and apoptosis-related proteins in mediating the apoptotic mechanisms were investigated using apoptosis antibody array, ELISA and Western blotting analysis.

RESULTS:

Combinatorial study between γ-tocotrienol at a concentration range (0-24µg/ml) and fixed IC₂₀ concentration of jerantinine A (0.16µg/ml) induced a potent antiproliferative effect on U87MG cells and led to a reduction on the new half maximal inhibitory concentration of γ-tocotrienol (i.e._tIC₅₀=1.29µg/ml) as compared to that of individual γ-tocotrienol (i.e. IC₅₀=3.17µg/ml). A reduction on undesirable toxicity to MRC5 normal cells was also observed. G0/G1 cell cycle arrest was evident on U87MG cells receiving IC₅₀ of individual γ-tocotrienol and combined low-concentration compounds (1.29µg/ml γ-tocotrienol + 0.16µg/ml jerantinine A), whereas, a profound G2/M arrest was evident on cells treated with IC₅₀ of individual jerantinine A. Additionally, individual jerantinine A and combined compounds (except individual γ-tocotrienol) caused a disruption of microtubule networks triggering Fas- and p53-induced apoptosis mediated via the death receptor and mitochondrial pathways.

CONCLUSIONS:

These findings demonstrated that the combined use of lower concentrations of γ-tocotrienol and jerantinine A induced potent cytotoxic effects on U87MG cancer cells resulting in a reduction on the required individual concentrations and thereby minimizing toxicity of jerantinine A towards non-cancerous MRC5 cells as well as probably overcoming the high-dose limiting application of γ-tocotrienol. The multi-targeted mechanisms of action of the combination approach have shown a therapeutic potential against brain cancer in vitro and therefore, further in vivo investigations using a suitable animal model should be the way forward.

Azzi A.

Mol Aspects Med. 2017 Jun 17. pii: S0098-2997(17)30041-9. doi: 10.1016/j.mam.2017.06.004. [Epub ahead of print]

Abstract

Four tocopherols are available in nature and are absorbed with the diet, but only one RRR-α-tocopherol satisfies the criteria of being a vitamin. The biological activity of the different tocopherols studied in the rat by the resorption-gestation test has been inconsistently extrapolated to human beings where the tocopherols have no influence on a successful pregnancy. Diminution of RRR-α-tocopherol intake results in diseases characterized by ataxia, whose pathogenetic mechanism, despite vigorous claims, has not been clarified. The calculation of the Daily Reference Intake (DRI), necessary to prevent disease, is based on an obsolete test, the peroxide-induced erythrocyte hemolysis, called the gold standard, but of highly questioned validity. If many epidemiological studies have given positive results, showing prevention by high vitamin E containing diets of cardiovascular events, neurodegenerative disease, macular degeneration and cancer, the clinical confirmatory intervention studies were mostly negative. On the positive side, besides preventing vitamin E deficiency diseases, vitamin E has shown efficacy as anti-inflammatory and immune boosting compound. It has also shown some efficacy in protecting against nonalcoholic hepato-steatosis. At a molecular level, vitamin E and some of its metabolites have shown capacity of regulating cell signaling and modulating gene transcription.

Horák D, Pustovyy VI, Babinskyi AV, Palyvoda OM, Chekhun VF, Todor IN, Kuzmenko OI.

Int J Nanomedicine. 2017 Jun 6;12:4257-4268. doi: 10.2147/IJN.S137574. eCollection 2017.

Abstract

Maghemite (γ-Fe₂O₃) nanoparticles were obtained by coprecipitation of ferrous and ferric salts in an alkaline medium followed by oxidation; the nanoparticles were coated with poly(N,N-dimethylacrylamide) (PDMA) and characterized by transmission electron microscopy, attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering, thermogravimetric and elemental analyses, and magnetic measurements in terms of particle morphology, size, polydispersity, amount of coating, and magnetization, respectively. The effects of α-tocopherol (Toc) and its phenolic (Toc-6-OH) and acetate (Toc-6-Ac) derivatives on Fe²⁺ release from γ-Fe₂O₃@PDMA, as well as from γ-Fe₂O₃ and CuFe₂O₄ nanoparticles (controls), were examined in vitro using 1,10-phenanthroline. The presence of tocopherols enhanced spontaneous Fe²⁺ release from nanoparticles, with Toc-6-OH exhibiting more activity than neat Toc. All of the nanoparticles tested were found to initiate blood lipid oxidation in a concentration-dependent manner, as determined by analysis of 2-thiobarbituric acid reactive species. Wistar rats with Walker-256 carcinosarcoma (a model of mammary gland carcinosarcoma) received Toc-6-Ac, magnetic nanoparticles, or their combination per os, and the antitumor activity of each treatment was determined in vivo. γ-Fe₂O₃@PDMA nanoparticles exhibited increased antitumor activity compared to both commercial CuFe₂O₄ particles and the antitumor drug doxorubicin. Moreover, increased antitumor activity was observed after combined administration of γ-Fe₂O₃@PDMA nanoparticles and Toc-6-Ac; however, levels of bilirubin, aspartate aminotransferase, and white bloods normalized and did not differ from those of the intact controls. The antitumor activity of the γ-Fe₂O₃ nanoparticles strongly correlated with Fe²⁺ release from the nanoparticles but not with nanoparticle-initiated lipid peroxidation in vitro.

Jang Y, Rao X, Jiang Q

J Nutr Biochem. 2017 Apr 12;46:49-56. doi: 10.1016/j.jnutbio.2017.04.003. [Epub ahead of print]

Abstract

Vitamin E gamma-tocotrienol (γTE) is known to have anticancer effects, but mechanisms underlying these actions are not clear. Here using liquid chromatography tandem mass spectrometry, we show that γTE induced marked changes of sphingolipids including rapid elevation of dihydrosphingosine and dihydroceramides (dhCers) in various types of cancer cells. The elevation of dihydrosphingolipids coincided with increased cellular stress, as indicated by JNK phosphorylation, and was prior to any sign of induction of apoptosis. Chemically blocking de novo synthesis of sphingolipids partially counteracted γTE-induced apoptosis and autophagy. Experiments using ¹³C₃, ¹⁵N-labeled l-serine together with enzyme assays indicate that γTE inhibited cellular dihydroceramide desaturase (DEGS) activity without affecting its protein expression or de novo synthesis of sphingolipids. Unlike the effect on dhCers, γTE decreased ceramides (Cers) after 8-h treatment but increased C_18:0-Cer and C_16:0-Cer after 16 and 24 h, respectively. The increase of Cers coincides with γTE-induced apoptosis and autophagy. Since γTE inhibits DEGS and decreases de novo Cer synthesis, elevation of Cers during prolonged γTE treatment is likely caused by sphingomeylinase-mediated hydrolysis of sphingomyelin. This idea is supported by the observation that an acid sphingomeylinase inhibitor partially reversed γTE-induced cell death. Our study demonstrates that γTE altered sphingolipid metabolism by inhibiting DEGS activity and possibly by activating SM hydrolysis during prolonged treatment in cancer cells.

Zhu YJ, Bo YC, Liu XX, Qiu CG.

Asia Pac J Clin Nutr. 2017 Mar;26(2):271-277. doi: 10.6133/apjcn.032016.04.

Abstract

Several epidemiological studies investigating the association between dietary vitamin E intake and the risk of lung cancer have demonstrated inconsistent results. Hence, a meta-analysis was conducted to summarise evidence of the association of dietary vitamin E intake with the risk of lung cancer. In this meta-analysis, a systematic literature search of PubMed and Web of Science was conducted to identify relevant studies published from 1955 to April 2015. If p<0.05 or I2 >50%, a random effect model was used to estimate overall relative risks (RRs) and 95% confidence intervals (CIs). Otherwise, a fixed effect model was applied. Publication bias was estimated using the funnel plot and Egger’s test. The doseresponse relationship was assessed using the method of restricted cubic splines with 4 knots at percentiles 5, 35, 65, and 95 of the distribution. The pooled RR of lung cancer for the highest versus lowest categories of dietary vitamin E intake was 0.84 (95% CI=0.76-0.93). With every 2 mg/d increase in dietary vitamin E intake, the risk of lung cancer statistically decreased by 5% (RR=0.95, 95% CI =0.91-0.99, plinearity=0.0237). Our analysis suggests that higher dietary vitamin E intake exerts a protective effect against lung cancer.

Ye J, Dong W, Yang Y, Hao H, Liao H, Wang, Han X, Jin Y, Xia X, Liu Y.

Pharm Res. 2017 Mar 21. doi: 10.1007/s11095-017-2141-3. [Epub ahead of print]

Abstract

To overcome the drawbacks of high dose regimen and improve the outcomes of chemotherapy at a low dose, an immunotherapeutic nanoemulsion based combination of chemotherapeutic agent (paclitaxel) with immunomodulatory agent (vitamin E) was developed and evaluated for their antitumor effect against breast cancer. A total of five nanoemulsions loaded with various content of vitamin E were prepared and characterized. The immunoregulatory effects of vitamin E along with the overall antitumor efficacy of vitamin E-rich nanoemulsion with a low dose of paclitaxel were investigated through in vitro and in vivo experiments. Vitamin E-rich nanoemulsion exhibited relatively narrow size distribution, high entrapment efficiency and controlled in vitro release profile. In RAW264.7 cells, vitamin E-rich nanoemulsion significantly enhanced the secretion of Th1 cytokines and down-regulated the secretion of Th2 cytokine. In a co-culture system, vitamin E-rich nanoemulsion induced a high apoptosis rate in MDA-MB-231 cells as compared with vitamin E-low nanoemulsion. Furthermore, vitamin E-rich nanoemulsion exhibited superior in vivo antitumor efficacy in comparison with Taxol and vitamin E-low nanoemulsion at a paclitaxel dose of 4 mg/kg. Vitamin E-rich nanoemulsion has great potential for the treatment of breast cancers with a low dose of paclitaxel via driving Th1 immune response.

Abu-Fayyad A, Nazzal S.

Int J Pharm. 2017 Mar 15;519(1-2):145-156. doi: 10.1016/j.ijpharm.2017.01.020. Epub 2017 Jan 16.

Abstract

Vitamin E refers to a group of saturated tocopherol (T) isomers and the biologically more active unsaturated tocotrienol (T₃) isomers. PEGylated α-tocopherol, commercially known as Vitamin E TPGS, has been used as an emulsifier and therapeutic agent for children with vitamin E deficiency. Limited information, however, is available about the PEG conjugates of the tocotrienol isomers of vitamin E. The current work was therefore undertaken to synthesize and characterize the water soluble polyethylene glycol (PEG 350 and 1000) derivatives of T and T₃. Yield and the identity of the synthesized products were confirmed by ¹H NMR, mass spectroscopy, HPLC, and thermal analysis. The self-assembly of the PEGylated vitamin E isomers in water at critical micelle concentrations (CMC) was further confirmed by size, zeta, and Cryo-TEM image analysis. While stable at pH 7.4, PEG conjugates were found to rapidly hydrolyze at pH 1.2. Our data showed that PEGylated T₃ isomers were significantly more active as inhibitors for P-glycoprotein than PEGylated T. The in vitro cytotoxicity of the conjugates was also tested against a large panel of normal and tumorigenic cells. Of the conjugates, γ-T₃PGS 1000 and δ-T₃PGS 1000 were found to have the least toxicity against non-tumorigenic breast and pancreatic cell lines, which may be advantageous for its use as functional excipients in drug delivery. The results from the current work have demonstrated the feasibility of synthesizing PEGylated conjugates of vitamin E isomers and highlighted the potential use of these conjugates in drug delivery as functional and safer excipients especially for γ-T₃PGS 1000 and δ-T₃PGS 1000 conjugate.

Tu L, Wang M, Zhao WY, Zhang ZZ, Tang DF, Zhang YQ, Cao H, Zhang ZG.

Mater Sci Eng C Mater Biol Appl. 2017 Mar 1;72:177-184. doi: 10.1016/j.msec.2016.10.052. Epub 2016 Oct 26.

Abstract

Gastrointestinal stromal tumors (GIST) are one of the most common forms of mesenchymal cancers of the gastrointestinal tract. Although chemotherapeutic drugs inhibited the proliferation of GIST, however, sizable proportion of people developed resistance and therefore difficult to treat. In the present study, O-carboxymethyl chitosan (OCMC)-tocopherol polymer conjugate was synthesized and formulated into stable polymeric nanoparticles. The main aim of present study was to increase the therapeutic efficacy of miR-218 in GIST. The mean size of nanoparticles was ~110nm with a spherical shape. The miR-218 NP has been shown inhibit the cell proliferation and exhibited a superior cell apoptosis. The miR-218 NP inhibited the cell invasion and promoted the apoptosis of GIST cancer cells. In the present study, we have successfully showed that KIT1 is the target gene of miR-218 as shown by the luciferase reporter assay. These findings collectively suggest the miR-218 loaded nanoparticle by virtue of effective transfection could act as a tumor suppressor miRNA in the treatment of GIST.

Abu-Fayyad A, Nazzal S.

Int J Pharm. 2017 Jan 16;519(1-2):145-156. doi: 10.1016/j.ijpharm.2017.01.020. [Epub ahead of print]

Abstract

Alias D, Ruiz-Tovar J, Moreno A, Manso B, Diaz G, Duran M, Garcia-Olmo D.

Surg Infect (Larchmt). 2017 Jan 6. doi: 10.1089/sur.2016.199. [Epub ahead of print]

Abstract

Despite several interventions having been adopted to reduce the incidence of incisional surgical site infection (SSI), it still remains a challenge for surgeons, because incisional SSI is a common cause of health-care-associated infection, leading to increased morbidity, prolonged hospital stay, patient discomfort, and increased sanitary costs. The aim of this study was to evaluate the effect on incisional SSI of vitamin E ointment in the subcutaneous tissue of patients undergoing a laparoscopic colorectal surgical procedure. A randomized study was performed. Patients with colorectal neoplasms undergoing an elective laparoscopic surgical procedure were included. The patients were randomized into two groups: Those patients undergoing a subcutaneous vitamin E ointment application (Group 1) and those patients who did not receive it (Group 2). Incisional SSI, post-operative pain, and analytical acute phase reactants were analyzed. There were 108 patients who were assessed for eligibility, and 101 patients were analyzed. The incisional SSI rate was 4% in Group 1 and 17.6% in Group 2 (p = 0.03). Mean post-operative pain, 24 hours after operation, was 17.3 ± 10.5 mm in Group 1 and 31.9 ± 18.9 mm in Group 2 (p < 0.001). Median hospital stay was six days in Group 1 and eight days in Group 2 (p < 0.001). White blood cell count was significantly lower in Group 1 (p < 0.001). Conclusion, the subcutaneous application of sterile vitamin E acetate ointment leads to a reduction in the incisional SSI rate, lower post-operative pain, and decrease in C-reactive protein and white blood cell count.