Reduced infiltration of regulatory T cells in tumours from mice fed daily with gamma-tocotrienol supplementation.

Gamma-tocotrienol (γT3) is an analogue of vitamin E with beneficial effects on the immune system, including immune-modulatory properties. This study reports the immune-modulatory effects of daily supplementation of γT3 on host T helper (Th) and T regulatory cell (Treg ) populations in a syngeneic mouse model of breast cancer. Female BALB/c mice were fed with either γT3 or vehicle (soy oil) for 2 weeks via oral gavage before they were inoculated with syngeneic 4T1 mouse mammary cancer cells (4T1 cells). Supplementation continued until the mice were euthanized. Mice (n = 6) were euthanized at specified time-points for various analysis (blood leucocyte, cytokine production and immunohistochemistry). Tumour volume was measured once every 7 days. Gene expression studies were carried out on tumour-specific T lymphocytes isolated from splenic cultures. Supplementation with γT3 increased CD4+ (p < 0.05), CD8+ (p < 0.05) T-cells and natural killer cells (p < 0.05) but suppressed Treg cells (p < 0.05) in peripheral blood when compared to animals fed with the vehicle. Higher interferon (IFN)-γ and lower transforming growth factor (TGF)-ꞵ levels were noted in the γT3 fed mice. Immunohistochemistry findings revealed higher infiltration of CD4+ cells, increased expression of interleukin-12 receptor-beta-2 (IL-12ꞵ2R), interleukin (IL)-24 and reduced expression of cells that express the forkhead box P3 (FoxP3) in tumours from the γT3-fed animals. Gene expression studies showed the down-regulation of seven prominent genes in splenic CD4+ T cells isolated from γT3-fed mice. Supplementation with γT3 from palm oil-induced T cell-dependent cell-mediated immune responses and suppressed T cells in the tumour microenvironment in a syngeneic mouse model of breast cancer.

Gamma-tocotrienol modifies methylation of HOXA10, IRF4 and RORα genes in CD4+ T-lymphocytes: Evidence from a syngeneic mouse model of breast cancer.

DNA methylation plays a crucial role in polarising naïve lymphocytes towards their various sub-populations to fight against many immune challenges including establishment of tumour. Gamma-tocotrienol (γT3) is a natural form of vitamin E, reported to possess anticancer and immunomodulatory effects. This study reports the anticancer effects of γT3 through modulation of DNA methylation in several genes in CD4+ T-lymphocytes using a syngeneic mouse model of breast cancer. Female BALB/c mice were fed with γT3 or vehicle (soy oil) for two-weeks via oral gavage before they were inoculated with 4T1 mouse mammary cancer cells. Supplementation continued until the mice were sacrificed. At autopsy, blood was collected via cardiac puncture and CD4+ T-cells were isolated for DNA extraction. The DNA was analysed using the EpiTech Methyl II mouse T-helper cell differentiation PCR array. γT3 supplementation reduced tumour growth in the tumour-induced animals and modulated host immune system by inducing changes in DNA methylation patterns of the HOXA10, IRF4 and RORα genes, which are involved in differentiation and clonal expansion of CD4+ T-cells. Results suggest that γT3 may enhance cell-mediated immune response in mice with breast cancer by inducing changes in DNA methylation pattern.

Advancing the Role of Gamma-Tocotrienol as Proteasomes Inhibitor: A Quantitative Proteomic Analysis of MDA-MB-231 Human Breast Cancer Cells.

Tocotrienol, an analogue of vitamin E has been known for its numerous health benefits and anti-cancer effects. Of the four isoforms of tocotrienols, gamma-tocotrienol (γT3) has been frequently reported for their superior anti-tumorigenic activity in both in vitro and in vivo studies, when compared to its counterparts. In this study, the effect of γT3 treatment in the cytoplasmic and nuclear fraction of MDA-MB-231 human breast cancer cells were assessed using the label-free quantitative proteomics analysis. The cytoplasmic proteome results revealed the ability of γT3 to inhibit a group of proteasome proteins such as PSMA, PSMB, PSMD, and PSME. The inhibition of proteasome proteins is known to induce apoptosis in cancer cells. As such, the findings from this study suggest γT3 as a potential proteasome inhibitor that can overcome deficiencies in growth-inhibitory or pro-apoptotic molecules in breast cancer cells. The nuclear proteome results revealed the involvement of important nuclear protein complexes which hardwire the anti-tumorigenesis mechanism in breast cancer following γT3 treatment. In conclusion, this study uncovered the advancing roles of γT3 as potential proteasomes inhibitor that can be used for the treatment of breast cancer.