The effect of Phloretin on human γδ T cells killing colon cancer SW-1116 cells

ObjectiveTo explore the effect and mechanism of Phloretin on human γδ T cells killing colon cancer SW-1116 cells.Methodsγδ T cells were amplified in vitro from human peripheral blood mononuclear cells through isopentenyl pyrophosphate method (IPP). After cocultured different concentrations of Phloretin with γδ T cells or SW-1116 cells for 48 h respectively, MTT assay was used to test the growth curve of these two cells; Flow cytometry to test the expression of Granzyme B (GraB), perforin (PFP), CD107a and IFN-γ of γδ T cells; Lactate dehydrogenase (LDH) release assay to test the cytotoxic activity of the γδ T cells on SW-1116 cells; and Western blot to test the Wnt3a expression of the γδ T cells.ResultsAfter cultured with IPP for ten days, the percentage of γδ T cells increased from 3.31 ± 3.00% to 78.40 ± 10.30%. Compared to the control group, when the concentration of Phloretin increased from 2.35 μg/ml to 18.75 μg/ml, it could significantly proliferate the γδ T cell growth (P < 0.05) and inhibit the growth of SW-1116 cells in dose–response, and the expression of GraB, PFP, CD107a and Wnt3a significantly increased (P < 0.05). Significant positive relationships were observed among CD107a and PFP, GraB, cytotoxicity (P < 0.05). The percentage of IFN-γ producing γδ T cells treated with Phloretin was significantly higher than control group.ConclusionPhloretin can enhance the killing effect of γδ T cells on SW-1116 cells; the mechanism may be that Phloretin could proliferate the γδ T cell growth, increase the expression of PFP and GraB, activate the Wnt signaling pathway, and produce higher level of IFN-γ. Indeed CD107a expression probably correlates quite well with antitumor activity.

► Phloretin can enhance the killing activity of γδ T cells to SW-1116 cells.
► Phloretin increase the expression of PFP and GraB.
► Phloretin can activate Wnt signaling pathway and proliferate γδ T cell growth.
► The γδ T cells with positive CD107a can indicate that the cells have killing activity.
► Phloretin could proliferate the γδ T cells producing higher level of IFN-γ.