Tocotrienols are good adjuvants for developing cancer vaccines - PubMed (original) (raw)
Tocotrienols are good adjuvants for developing cancer vaccines
Sitti Rahma Abdul Hafid et al. BMC Cancer. 2010.
Abstract
Background: Dendritic cells (DCs) have the potential for cancer immunotherapy due to their ability to process and present antigens to T-cells and also in stimulating immune responses. However, DC-based vaccines have only exhibited minimal effectiveness against established tumours in mice and humans. The use of appropriate adjuvant enhances the efficacy of DC based cancer vaccines in treating tumours.
Methods: In this study we have used tocotrienol-rich fraction (TRF), a non-toxic natural compound, as an adjuvant to enhance the effectiveness of DC vaccines in treating mouse mammary cancers. In the mouse model, six-week-old female BALB/c mice were injected subcutaneously with DC and supplemented with oral TRF daily (DC+TRF) and DC pulsed with tumour lysate from 4T1 cells (DC+TL). Experimental mice were also injected with DC pulsed with tumour lysate and supplemented daily with oral TRF (DC+TL+TRF) while two groups of animal which were supplemented daily with carrier oil (control) and with TRF (TRF). After three times vaccination, mice were inoculated with 4T1 cells in the mammary breast pad to induce tumour.
Results: Our study showed that TRF in combination with DC pulsed with tumour lysate (DC+TL+TRF) injected subcutaneously significantly inhibited the growth of 4T1 mammary tumour cells as compared to control group. Analysis of cytokines production from murine splenocytes showed significant increased productions of IFN-gamma and IL-12 in experimental mice (DC+TL+TRF) compared to control, mice injected with DC without TRF, mice injected with DC pulsed with tumour lysate and mice supplemented with TRF alone. Higher numbers of cytotoxic T cells (CD8) and natural killer cells (NK) were observed in the peripheral blood of TRF adjuvanted DC pulsed tumour lysate mice.
Conclusion: Our study show that TRF has the potential to be an adjuvant to augment DC based immunotherapy.
Figures
Figure 1
(a) DCs stained with CD11c monoclonal antibody, i) untreated DC was stained with CD11c compared with unstained DC. ii) Stained DC treated with 8 μg/ml of TRF compared with unstained DC. (b) DCs stained with CD86, i) untreated DC. ii) DC treated with 8 μg/ml of TRF. (c) DCs stained with MHC class II, (i) untreated DC. ii) DC treated with 8 μg/ml of TRF.
Figure 2
Pictures of DC taken by microscopy with 100× magnification at day 0, 5, 7 and 9.
Figure 3
Viability of (a) 4T1 cells decreased after treated with different concentrations of TRF. IC50 recorded at 8 μg/ml of TRF treatment. b) Viability of DC increased in higher concentration of TRF up to 25 μg/ml. c) Splenocytes culture treated with different concentrations of TRF showed increased cell viability until 20 μg/ml of treatment.
Figure 4
The amount of IFN-γ produced by (a) DCs treated with different concentrations of TRF (2 to 15 μg/ml) and (b) splenocytes treated with different concentrations of TRF (2 to 15 μg/ml) (c) DCs co-cultured with tumour lysate from 4T1 cells in the presence of 8 μg/ml TRF for 72 h. Following 72 hours of culture, the supernatants of control, TRF alone, DC with tumour lysate from 4T1 cells (DC+TL), DC with 8 ug/ml of TRF (DC+TRF), DC with tumour lysate from 4T1 cells and 8 μg/ml TRF (DC+TL+TRF) were harvested. The amount of IFN-γ in the supernatant was determined using ELISA. The amount of IL-12 produced by (d) DCs treated with different concentrations of TRF (2 to 15 μg/ml) and (e) splenocytes treated with different concentrations of TRF (2 to 15 μg/ml) (f) DCs co-culture with tumour lysate (DC+TL), in the presence of 8 ug/ml TRF (DC+TL+TRF), DC alone in the presence of ug/ml TRF (DC+TRF), TRF alone and control for 72 h.
Figure 5
Tumour size of the tumours induced in the control, TRF alone, DC+TL, DC+TRF and DC+TL+TRF groups were measured. The DC+TL group were injected with DC that has been primed with tumour lysate from 4T1 cells and received daily oral supplementation of carrier oil while the DC+TL+TRF group were injected with DC primed with tumour lysate from 4T1 cells and supplemented daily with 1 mg/ml TRF orally. For the TRF alone, mice were only supplemented with TRF oil daily and for DC+TRF, DC fresh without tumour lysate and supplemented with TRF oil daily.
Figure 6
Splenocytes (1 × 105 in each well) harvested from each group were cultured in the presence of 1 μg/ml Con A for 72 hours in 96 well plate. The culture supernatant was collected and (a) IFN-γ produced was measured by using an ELISA kit. (b) IL-12 produced was measured by using an ELISA kit.
Figure 7
The percentage of a) NK cells and b) CD8+ T-lymphocytes in the control and experimental groups were determined by flow cytometric analyses.
References
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