Elimination of ALDH+ breast tumor initiating cells by docosahexanoic acid and/or gamma tocotrienol through SHP-1 inhibition of Stat3 signaling.

Study investigated the ability of docosahexaenoic acid (DHA) alone and in combination with gamma-tocotrienol (γT3) to eliminate aldehyde dehydrogenase positive (ALDH+) cells and to inhibit mammosphere formation, biomarker and functional assay for tumor initiating cells (TICs), respectively, in human triple negative breast cancer cells (TNBCs), and investigated possible mechanisms of action. DHA upregulated Src homology region 2 domain-containing protein tyrosine phosphatase-1 (SHP-1) protein levels and suppressed levels of phosphorylated signal transducer and activator of transcription-3 (pStat3) and its downstream mediators c-Myc, and cyclin D1. siRNA to SHP-1 enhanced the percentage of ALDH+ cells and Stat-3 signaling, as well as inhibited, in part, the ability of DHA to reduce the percentage of ALDH+ cells and Stat-3 signaling.

Synthesis and screening of novel vitamin E derivatives for anticancer functions.

α-TEA, RRR-α-tocopherol ether linked acetic acid, exhibits potent anticancer actions in vitro and in vivo; whereas, the parent molecule has no anticancer activity. In this study, we incorporated fluorine at the chroman head and/or ether linkage between the chroman head and phytyl tail of α-TEA as well as RRR-α-tocopherol to synthesize 6 vitamin E derivatives, and evaluated the anticancer actions in vitro for ability to induce cell death by apoptosis of human MCF-7 and MDA-MB-231 breast cancer cell lines and mouse mammary cancer cell line 66cl-4GFP. All derivatives, with the exception of compound 12, exhibited anticancer properties.

Involvement of de novo ceramide synthesis in gamma-tocopherol and gamma-tocotrienol-induced apoptosis in human breast cancer cells.

Scope: This study further examines mechanisms involved in the pro-apoptotic action of gamma-tocopherol (γT) and gamma-tocotrienol (γT3) in human breast cancer cell lines.

Methods And Results: γT upregulates phospho-JNK (pJNK), CCAAT/enhancer-binding protein homologous protein (CHOP), and death receptor-5 (DR5) protein expression as detected by Western blot assays. siRNA knockdown of JNK, CHOP, or DR5 shows that γT-induced apoptosis is JNK/CHOP/DR5 signaling dependent, which is similar to γT3-mediated apoptotic signaling.

Eliminating drug resistant breast cancer stem-like cells with combination of simvastatin and gamma-tocotrienol.

Present study shows that drug resistant human breast cancer cells are enriched in cancer stem-like cells (CSCs) and express elevated levels of Stat-3 signaling mediators, which contribute to CSC enrichment. Simvastatin (SVA) and gamma-tocotrienol (γT3) eliminate enriched CSCs and suppress expression of Stat-3 signaling mediators via inhibition of the mevalonate pathway and activation of de novo ceramide synthesis pathway, respectively. Combination of SVA+γT3 at low doses enhanced these actions via inhibition of the mevalonate pathway.

Simvastatin inhibition of mevalonate pathway induces apoptosis in human breast cancer cells via activation of JNK/CHOP/DR5 signaling pathway.

Simvastatin (SVA) was shown to up-regulate expression of death receptor-5 (DR5), CCAAT/enhancer binding protein homologous protein (CHOP) and phosphorylated c-Jun N-terminal kinase (pJNK) in human breast cancer cell lines. siRNA knockdown of DR5, CHOP or JNK significantly blocked SVA-induced apoptosis, demonstrating the importance of JNK/CHOP/DR5 signaling pathway in SVA-induced apoptosis. Exogenous addition of either mevalonate or geranylgeranyl pyrophosphate (GGPP) inhibited SVA activation of JNK/CHOP/DR5 pro-apoptotic pathway, indicating that activation of JNK/CHOP/DR5 pro-apoptotic pathway is dependent on SVA inhibition of 3-hydroxy-3-methylglutaryl Coenzyme A (HMG-CoA) reductase and its intermediate GGPP.

Distinct roles of different forms of vitamin E in DHA-induced apoptosis in triple-negative breast cancer cells.

Scope: Docosahexaenoic acid (DHA) has been shown to exhibit anticancer actions in vitro and in vivo in a variety of cancers. Here, we investigated the role for DHA in inducing apoptosis in triple-negative breast cancer (TNBC) and studied the mechanisms of action.

Methods And Results: DHA induces apoptosis as detected by Annexin V-FITC/PI assay as well as induces cleavage of caspase-8 and -9, endoplasmic reticulum stress (ERS), and elevated levels of death receptor-5 (DR5) protein expression as detected by western blot assays.

Targeting cholesterol-rich microdomains to circumvent tamoxifen-resistant breast cancer.

Introduction: Adjuvant treatment with tamoxifen substantially improves survival of women with estrogen-receptor positive (ER+) tumors. Tamoxifen resistance (TAMR) limits clinical benefit. RRR-α-tocopherol ether-linked acetic acid analogue (α-TEA) is a small bioactive lipid with potent anticancer activity.

α-TEA cooperates with chemotherapeutic agents to induce apoptosis of p53 mutant, triple-negative human breast cancer cells via activating p73.

Introduction: Successful treatment of p53 mutant, triple-negative breast cancers (TNBC) remains a daunting challenge. Doxorubicin (DOXO) and cisplatin (CDDP) are standard-of-care treatments for TNBC, but eventually fail due to acquired drug resistance and toxicity. New treatments for overcoming drug resistance and toxicity in p53 mutant, TNBC are therefore badly needed.

α-TEA-induced death receptor dependent apoptosis involves activation of acid sphingomyelinase and elevated ceramide-enriched cell surface membranes.

Background: Alpha-tocopherol ether-linked acetic acid (α-TEA), an analog of vitamin E (RRR-alpha-tocopherol), is a potent and selective apoptosis-inducing agent for human cancer cells in vivo and in vitro. α-TEA induces apoptosis via activation of extrinsic death receptors Fas (CD95) and DR5, JNK/p73/Noxa pathways, and suppression of anti-apoptotic mediators Akt, ERK, c-FLIP and survivin in breast, ovarian and prostate cancer cells.

Results: In this study, we demonstrate that α-TEA induces the accumulation of cell surface membrane ceramide, leading to co-localization with Fas, DR5, and FADD, followed by activation of caspases-8 and -9 and apoptosis in human MDA-MB-231 breast cancer cells.

α-TEA induces apoptosis of human breast cancer cells via activation of TRAIL/DR5 death receptor pathway.

Vitamin E derivative RRR-α-tocopherol ether-linked acetic acid analog (α-TEA) induces apoptosis in MCF-7 and HCC-1954 human breast cancer cells in a dose- and time-dependent manner. α-TEA induces increased levels of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and death receptor-5 (DR5) and decreased levels of antiapoptotic factor, cellular FLICE-like inhibitory protein (c-FLIP L). DR5/TRAIL induced apoptosis involves downregulation of c-FLIP (L), caspase-8 activation, activated proapoptotic mediators tBid and Bax, mitochondrial permeability transition, and activation of caspase-9.

Role of endoplasmic reticulum stress in alpha-TEA mediated TRAIL/DR5 death receptor dependent apoptosis.

Background: Alpha-TEA (RRR-alpha-tocopherol ether-linked acetic acid analog), a derivative of RRR-alpha-tocopherol (vitamin E) exhibits anticancer actions in vitro and in vivo in variety of cancer types. The objective of this study was to obtain additional insights into the mechanisms involved in alpha-TEA induced apoptosis in human breast cancer cells.

Methodology/principal Findings: alpha-TEA induces endoplasmic reticulum (ER) stress as indicated by increased expression of CCAAT/enhancer binding protein homologous protein (CHOP) as well as by enhanced expression or activation of specific markers of ER stress such as glucose regulated protein (GRP78), phosphorylated alpha subunit of eukaryotic initiation factor 2 (peIF-2alpha), and spliced XBP-1 mRNA.

Downregulation of Epidermal Growth Factor Receptor Expression Contributes to alpha-TEA's Proapoptotic Effects in Human Ovarian Cancer Cell Lines.

RRR-alpha-tocopherol derivative alpha-TEA (RRR-alpha-tocopherol ether-linked acetic acid analog) has been shown to be a potent antitumor agent both in vivo and in vitro. In this study, we investigated the effects of alpha-TEA on the expression of epidermal growth factor receptor (EGFR) family members, ErbB1, 2 and 3, and the role of ErbB 2 and 3 in alpha-TEA-induced apoptosis and suppression of Akt, FLIP and survivin in the cisplatin-sensitive (A2780S) and -resistant (A2780/CP70R) human ovarian cancer cell lines. Data show that alpha-TEA's ability to induced apoptosis was associated with reduced expression of ErbB1 (cisplatin-resistant cells), 2 and 3 (both cell types) and reduced levels of the phosphorylated (active) form of Akt; as well as, reduced levels of FLIP and survivin proteins in both cell types.

Tocotrienols induce apoptosis in breast cancer cell lines via an endoplasmic reticulum stress-dependent increase in extrinsic death receptor signaling.

Tocotrienols are naturally occurring forms of vitamin E based on their structural similarity. This study focused on investigating anticancer effects of tocotrienols and the mechanisms of apoptosis induction by tocotrienols in vivo and in vitro. Dietary delivery of γ-tocotrienol (γ-T3) suppressed tumor growth in a syngeneic implantation mouse mammary cancer model by inhibiting cell proliferation and inducing apoptosis.

Anticancer actions of natural and synthetic vitamin E forms: RRR-alpha-tocopherol blocks the anticancer actions of gamma-tocopherol.

Two naturally occurring dietary sources of vitamin E (i.e. RRR-alpha-tocopherol (alphaT) and RRR-gamma-tocopherol (gammaT)), the manufactured synthetic form of vitamin E, all-racemic-alpha-tocopherol (all-rac-alphaT), as well as a potent antitumor analog of vitamin E, RRR-alpha-tocopherol ether-linked acetic acid analog (alpha-TEA), were assessed for anticancer actions.

Aerosol delivery of liposomal formulated paclitaxel and vitamin E analog reduces murine mammary tumor burden and metastases.

Paclitaxel is a chemotherapeutic agent used for the treatment of metastatic breast cancer. 2,5,7,8-Tetramethyl-2R-(4R, 8R-12-trimethyltridecyl) chroman-6-yloxyacetic acid (alpha-TEA) is an analog of vitamin E that inhibits primary tumor growth and the incidence of lymphatic and pulmonary metastases in preclinical animal models. Here, the efficacy of sequential treatment with paclitaxel and alpha-TEA was tested in the BALB/c syngeneic 66cl-4-GFP mammary cancer model.

Vitamin E analog alpha-TEA, methylseleninic acid, and trans-resveratrol in combination synergistically inhibit human breast cancer cell growth.

Alpha-tocopherol ether-linked acetic acid analog [2,5,7,8-tetramethyl-2R-(4R, 8R-12-trimethyltridecyl) chroman-6-yloxyacetic acid (alpha-TEA)] is a novel form of vitamin E effective at killing cancer cells but not normal cells. alpha -TEA alone and together with methylseleninic acid (MSA) and trans-resveratrol (t-RES) were investigated for ability to induce apoptosis, DNA synthesis arrest, and cellular differentiation and inhibit colony formation in human MDA-MB-435-F-L breast cancer cells in culture. The 3 agents alone were effective in inhibiting cell growth by each of the 4 different assays, and 3-way combination treatments synergistically inhibited cell proliferation in each assay in comparison to individual treatments.

In vitro and in vivo evaluation of anticancer actions of natural and synthetic vitamin E forms.

The goal of these studies was to investigate the potential anticancer properties of two naturally occurring plant sources and two manufactured synthetic forms of vitamin E, i. e., RRR-alpha-tocopherol (alphaT), RRR-gamma-tocopherol (gammaT), all-rac-alpha-tocopherol (all-rac-alphaT), and all-rac-alpha-tocopheryl acetate (all-rac-alphaTAc) in breast cancer models.

In vivo and in vitro studies of anticancer actions of alpha-TEA for human prostate cancer cells.

Background: Vitamin E analog, 2,5,7,8-tetramethyl-2R-(4R,8R, 12-trimethyltridecyl) chroman-6-yloxyacetic acid, referred to as alpha-TEA induces apoptosis in a variety of human cancer cells in cell culture and reduces tumor burden and metastases in preclinical animal models of breast and ovarian cancer. The goal of this study was to determine in vivo anticancer efficacy of alpha-TEA against human prostate cancer cells and identify mechanisms of action.

Methods: A PC-3-GFP xenograft model was used to assess the effects of alpha-TEA formulated in liposomes and administered orally on tumor burden and metastases.

Critical roles for JNK, c-Jun, and Fas/FasL-Signaling in vitamin E analog-induced apoptosis in human prostate cancer cells.

Background: Alpha-tocopherol ether-linked acetic acid (alpha-TEA), an analog of vitamin E (RRR-alpha-tocopherol), is a potent pro-apoptotic agent for human cancer cells in vivo and in vitro.

Methods: alpha-TEA-induced apoptosis was investigated in LNCaP and PC-3 human prostate cancer cells. Apoptosis was measured by DAPI-staining and FACS analyses of the sub-G1 fraction.

Vitamin E analog, alpha-tocopherol ether-linked acetic acid analog, alone and in combination with celecoxib, reduces multiplicity of ultraviolet-induced skin cancers in mice.

The goals of this study were to determine whether alpha-tocopherol ether-linked acetic acid analog (alpha-TEA), a novel vitamin E analog, and celecoxib, alone or in combination, when administered as a late intervention can reduce the ultraviolet-induced nonmelanoma skin-tumor burden of established tumors, prevent additional tumors from developing, and prevent tumor recurrence once treatments are stopped. Hairless SKH-1 female mice were ultraviolet-irradiated for 24 weeks, divided into treatment groups so that each group had approximately 5.8 tumors/mouse, and then treated with 72 mug of liposome-formulated alpha-TEA by aerosol inhalation, 500 p.

Involvement of JNK/p73/NOXA in vitamin E analog-induced apoptosis of human breast cancer cells.

Microarray analyses of human MDA-MB-435 breast cancer cells treated with vitamin E analog 2,5,7,8-tetramethyl-2R-(4R,8R,12-trimethyltridecyl) chroman-6-yloxy acetic acid (alpha-TEA) showed over 400 genes to be modulated. Thirty-four genes deemed of interest based on potential involvement in anticancer activities of alpha-TEA fell into six categories: apoptosis related, signal transduction, cell cycle related, cell adhesion and motility, transcriptional regulators, and membrane traffic related. The gene (PMAIP1) for NOXA was studied further.

Liposomal or nanoparticle alpha-TEA reduced 66cl-4 murine mammary cancer burden and metastasis.

Efficacy of alpha-TEA formulated in liposome or biodegradable poly(D, L-lactide-co-glycolide) (PLGA) nanoparticle was evaluated in a BALB/c clone 66cl-4 mammary cancer mouse model using oral delivery. alpha-TEA-loaded liposome or nanoparticle at 5 mg, but not 2.5 mg/day, significantly reduced tumor burden (p < 0.

RRR-gamma-tocopherol induces human breast cancer cells to undergo apoptosis via death receptor 5 (DR5)-mediated apoptotic signaling.

Goal of this study was to investigate the pro-apoptotic properties of RRR-gamma-tocopherol (gammaT) in human breast cancer cells. gammaT was shown to induce cancer cells but not normal cells to undergo apoptosis, sensitize cancer cells to Tumor necrosis factor-Related Apoptosis-Inducing Ligand (TRAIL)-induced apoptosis, and increase death receptor 5 (DR5) mRNA, protein and cell surface expression. Knockdown of DR5 attenuated gammaT-induced apoptosis.

Vitamin E and cancer.

Perhaps not surprisingly, vitamin E which has been touted to be potentially beneficial for a variety of disorders, including cancer, heart disease, and even Alzheimer's disorder, based on its function as an antioxidant has failed to withstand the scrutiny of recent, double-blinded, placebo-controlled clinical trials, including failure to provide science-based support for vitamin E as a potent anticancer agent. Although less studied, vitamin E forms other than RRR-alpha-tocopherol or synthetic all-rac-alpha-tocopherol show promise as anticancer agents in preclinical studies. This chapter will (1) review basic information about natural and synthetic vitamin E compounds as well as vitamin E analogues, (2) summarize the current status of human intervention trials, (3) review data from preclinical cell culture and animal model studies of vitamin E compounds and novel vitamin E-based analogues in regards to future potential for cancer treatment, and (4) summarize some of the insights that have been gained into the anticancer mechanisms of action of vitamin E-based compounds which are providing interesting insights into their potent proapoptotic effects, which include restoration of apoptotic signaling pathways and blockage of prosurvival signaling events.

alpha-TEA inhibits survival and enhances death pathways in cisplatin sensitive and resistant human ovarian cancer cells.

RRR-alpha-tocopherol ether linked acetic acid analog (alpha-TEA), is a potential chemotherapeutic agent for ovarian cancer. Pro-death and pro-life signaling pathways were studied to understand the anti-cancer actions of alpha-TEA on cisplatin-sensitive (A2780S) and -resistant (A2780/cp70R) human ovarian cancer cells. Both cell lines were refractory to Fas; whereas, alpha-TEA sensitized them to Fas signaling.