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

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Published on Thursday, 18 July 2013

Abstract

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.

 

INTRODUCTION

Vitamin E succinate (VES, RRR-alpha-tocopheryl succinate), a derivative of vitamin E, is currently being characterized for its chemopreventive and chemotherapeutic potential. VES has been shown to inhibit the proliferation of several transformed cell types, including human prostate cancer cells. Previous studies have shown VES to inhibit tumor cell growth by a variety of mechanisms, including DNA synthesis arrest, induction of apoptosis, G1 cell cycle blockage, induced cellular differentiation, induced secretion and activation of transforming growth factor (TGF)-, enhanced expression of TGF- type II receptors, and enhanced cell surface expression of Fas (CD95).

A considerable amount of discussion regarding a hypothesis that vitamin E can protect against cancer, especially prostate cancer, has been generated by the recent alpha-Tocopherol, -Carotene Cancer Prevention Study of 29,133 male smokers aged 50-69 years in Finland. When the data were evaluated for the effect of daily supplements with 50 mg of synthetic dl-alpha-tocopheryl acetate for five to eight years on lung cancer incidence and mortality, vitamin E was reported to have no effect on the occurrence of lung cancer and no apparent effect on total mortality.

When the data were evaluated for effects of synthetic dl- -tocopheryl acetate on prostate cancer, it was reported that vitamin E-supplemented subjects had a 32% decrease in incidence of clinical prostate cancer but not in latent cancer. Furthermore, it was reported that prostate cancer mortality was 41% lower among the vitamin E-supplemented men. In view of these findings, it is important to point out that the studies reported here involve a different form of vitamin E, a succinate derivative of natural vitamin E (RRR-alpha-tocopheryl), RRR-alpha-tocopheryl succinate or VES. It is also important to point out that succinic acid and acetate esters of vitamin E [the naturally occurring single isomer form (RRR-alpha) or the synthetic mixture of 8 stereoisomers (dl-alpha)] are not active antioxidants unless the esterification is hydrolyzed and the free tocopherol is regenerated (reviewed in Reference 22). Because the acetate and succinate forms of RRR-alpha-Tocopherol and dl-alpha-Tocopherol are available over-the-counter as dietary supplements, it is of interest to ascertain potential mechanisms of action of these vitamin E compounds in human prostate cancer cells in cell culture and in animal models.

One interesting and consistent effect of VES on cancer cells in culture is its ability to induce apoptosis (9,15,17- 19,23,24). Apoptosis or programmed cell death is a well-established phenomenon in tissue development and homeostasis. This physiological process has been described as having independent triggering and transducing pathways, depending not only on the initiating agent itself, but on the environmental context of the cell or tissue. However, it appears that all cells undergoing the final execution phase of apoptosis exhibit similar end-stage morphological characteristics, such as cell membrane blebbing, nuclear condensation, and DNA fragmentation, caused by activation of common death-inducing proteases and endonucleases.

Defects in key components of death signaling pathways provide a survival advantage to cells and have been implicated as factors contributing to malignancy. Because induction of apoptosis by antineoplastic drugs is vital to the treatment of most cancers, alterations in the cell death signaling pathway may result in drug resistance. Defective signaling through the Fas-Fas ligand pathway has been demonstrated in certain cancer cell types. It is of interest that studies show that sensitivity to Fas-Fas ligand pathway(s) can be restored in certain tumor cells. Recent studies by this laboratory have demonstrated that Fas-resistant human breast cancer cells become responsive to agonistic anti-Fas antibody-triggered apoptosis after pretreatment or cotreatment with VES.

Fas (known as CD95 or APO-1) is a member of the tumor necrosis factor receptor and nerve growth factor receptor superfamily (reviewed in Reference 37). Fas contains a cytoplasmic death domain and, when trimerizered at the cell surface via Fas ligand or agonistic anti-Fas antibody, can initiate an apoptotic cascade that results in rapid cell death. Although Fas-induced apoptosis has been most extensively studied in T lymphocytes, recent studies show Fas expression in a wide range of cell types, including normal prostate cells. Downstream effects of Fas receptor activation are under investigation in an effort to identify the cellular components critical to its role in cell death, inasmuch as the presence of immunoreactive Fas is not itself sufficient to guarantee functionality of the receptor. Furthermore, the presence of altered Fas signaling has been demonstrated in prostate, breast, colon, and central nervous system cancer cells.

Here we report on the apoptosis-inducing abilities of VES on PrEC, LNCaP, and PC-3 cells. We show that 1) VES is an effective inducer of apoptosis in PC-3 and LNCaP human prostate carcinoma cells, but not in normal human prostate epithelial cells, PrEC, in cell culture, 2) VES-induced apoptosis can be augmented in an additive fashion in PC-3 cells and, in a synergistic fashion, in LNCaP cells by cotreatment with agonistic anti-Fas antibody, 3) cotreatment of cells with VES + agonistic Fas antibody induces apoptosis in LNCaP cells, which involves, at least in part, Fas signaling, 4) VES treatment enhances cell surface expression of Fas (CD95) by human prostate carcinoma cells, and 5) VES treatment enhances cell surface expression of Fas ligand.

 

About this publication.

See also:

- Official Web Site: The Di Bella Method;


 


- The Di Bella Method (A Fixed Part - Alpha tocopheryl acetate/Vitamin E, approximately 20 grams per day orally);

- Cancer and Vitamin E (analogues and/or derivatives) and cancer - In vitro, review and in vivo publications;

- Solution of retinoids in vitamin E in the Di Bella Method biological multitherapy;

- The Di Bella Method (A Fixed Part - All-Trans Retinoic Acid, Analogues and/or Derivatives - Approximately 60mg per day orally: 40mg per day Beta-Carotene/β-Carotene, 10mg per day ATRA and 10mg per day Axerophthol palmitate);

- All-Trans-Retinoic Acid (ATRA - analogues and/or derivatives) - In vitro, review and in vivo publications;

- The Di Bella Method (A Fixed Part - Cyclophosphamide 50mg tablets and/or Hydroxyurea 500mg tablets, one or two per day);

- The Di Bella Method (A Fixed Part - Bromocriptine and/or Cabergoline);

- The Di Bella Method (A Fixed Part - Somatostatin, Octreotide, Sandostatin LAR, analogues and/or derivatives);

- Somatostatin in oncology, the overlooked evidences - In vitro, review and in vivo publications;

- Publication, 2018 Jul: Over-Expression of GH/GHR in Breast Cancer and Oncosuppressor Role of Somatostatin as a Physiological Inhibitor (from Di Bella's Foundation);

- Publication, 2018 Sep: The over-expression of GH/GHR in tumour tissues with respect to healthy ones confirms its oncogenic role and the consequent oncosuppressor role of its physiological inhibitor, somatostatin: a review of the literature (from Di Bella's Foundation);

- Publication, 2019 Aug: The Entrapment of Somatostatin in a Lipid Formulation: Retarded Release and Free Radical Reactivity (from Di Bella's Foundation);

- Publication, 2019 Sep: Effects of Somatostatin and Vitamin C on the Fatty Acid Profile of Breast Cancer Cell Membranes (from Di Bella's Foundation);

- Publication, 2019 Sep: Effects of somatostatin, curcumin, and quercetin on the fatty acid profile of breast cancer cell membranes (from Di Bella's Foundation);

- Publication, 2020 Sep: Two neuroendocrine G protein-coupled receptor molecules, somatostatin and melatonin: Physiology of signal transduction and therapeutic perspectives (from Di Bella's Foundation);


 


- The Di Bella Method (DBM) in the treatment of prostate cancer: a preliminary retrospective study of 16 patients and a review of the literature;

- The Synergism of Somatostatin, Melatonin, Vitamins Prolactin and Estrogen Inhibitors Increased Survival, Objective Response and Performance Status In 297 Cases of Breast Cancer;

- Complete objective response, stable for 5 years, with the Di Bella Method, of multiple-metastatic carcinoma of the breast;

- Evaluation of the safety and efficacy of the first-line treatment with somatostatin combined with melatonin, retinoids, vitamin D3, and low doses of cyclophosphamide in 20 cases of breast cancer: a preliminary report;

- The Di Bella Method (DBM) improved survival, objective response and performance status in a retrospective observational clinical study on 122 cases of breast cancer;

- Complete objective response to biological therapy of plurifocal breast carcinoma;

- A retrospective observational study on cases of anaplastic brain tumors treated with the Di Bella Method: A rationale and effectiveness;

- Recurrent Glioblastoma Multiforme (grade IV – WHO 2007): a case of complete objective response achieved by means of the concomitant administration of Somatostatin and Octreotide – Retinoids – Vitamin E – Vitamin D3 – Vitamin C – Melatonin – D2 R agonists (Di Bella Method – DBM) associated with Temozolomide;

- The Di Bella Method DBM improved survival objective response and performance status in a retrospective observational clinical study on 23 tumours of the head and neck;

- Chronic Lymphocytic Leukemia: Long-Lasting Remission with Combination of Cyclophosphamide, Somatostatin, Bromocriptine, Retinoids, Melatonin, and ACTH;

- Somatostatin, retinoids, melatonin, vitamin D, bromocriptine, and cyclophosphamide in advanced non-small-cell lung cancer patients with low performance status;

- Somatostatin, retinoids, melatonin, vitamin D, bromocriptine, and cyclophosphamide in chemotherapy-pretreated patients with advanced lung adenocarcinoma and low performance status;

- Observations on the Report of a case of pulmonary adenocarcinoma with lymph node, hepatic and osseus metastasis;

- Neuroblastoma: Complete objective response to biological treatment;

- Cyclophosphamide plus Somatostatin, Bromocriptin, Retinoids, Melatonin and ACTH in the Treatment of Low-grade Non-Hodgkin’s Lymphomas at Advanced Stage: Results of a Phase II Trial;

- Relapse of High-Grade Non-Hodgkin’s Lymphoma After Autologous Stem Cell Transplantation: A Case Successfully Treated With Cyclophosphamide Plus Somatostatin, Bromocriptine, Melatonin, Retinoids, and ACTH;

- Low-grade Non-Hodgkin Lymphoma at Advanced Stage: A Case Successfully Treated With Cyclophosphamide Plus Somatostatin, Bromocriptine, Retinoids, and Melatonin;

- The Di Bella Method (DBM) improved survival, objective response and performance status in a retrospective observational clinical study on 55 cases of Lymphomas;

- Large B-cells Non-Hodgkin's Lymphoma, Stage IV-AE: a Case Report;

- Non-Hodgkin's Lymphoma, Stage III-B-E: a Case Report;

- Oesophageal squamocellular carcinoma: a complete and objective response;

- Pancreatic Adenocarcinoma: clinical records on 17 patients treated with Di Bella's Method;

- The Di Bella Method Increases by the 30% the survival rate for Pancreas tumors and for this reason should be proposed as first line therapy for this type of cancer.