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Combination treatment with decitabine and ionizing radiation enhances tumor cells susceptibility of T cells

View Article: PubMed Central - PubMed

ABSTRACT

Decitabine has been found to have anti-metabolic and anti-tumor activities in various tumor cells. Recently, the use of decitabine in combination with other conventional therapies reportedly resulted in improved anti-tumor activity against various tumors. Ionizing radiation (IR) is widely used as a cancer treatment. Decitabine and IR improve immunogenicity and susceptibility of tumor cells to immune cells by up-regulating the expression of various molecules such as major histocompatibility complex (MHC) class I; natural-killer group 2, member D (NKG2D) ligands; and co-stimulatory molecules. However, the effects of combining decitabine and IR therapies are largely unknown. Our results indicate that decitabine or IR treatment upregulates MHC class I, along with various co-stimulatory molecules in target tumor cells. Furthermore, decitabine and IR combination treatment further upregulates MHC class I, along with the co-stimulatory molecules, when compared to the effect of each treatment alone. Importantly, decitabine treatment further enhanced T cell-mediated cytotoxicity and release of IFN- γ against target tumor cells which is induced by IR. Interestingly, decitabine did not affect NKG2D ligand expression or NK cell-mediated cytotoxicity in target tumor cells. These observations suggest that decitabine may be used as a useful immunomodulator to sensitize tumor cells in combination with other tumor therapies.

No MeSH data available.


Related in: MedlinePlus

Expression of MHC class I and co-stimulatory molecules in tumor cells after treatment with decitabine, ionizing radiation (IR), or their combination.Tumor cells were treated with 5 μM decitabine for 24 h then exposed to radiation doses of 8 Gy. After 24 h, cells were harvested and the expression of MHC class 1 molecule in various tumor cells (a) and the expression of co-stimulatory molecules in A549 cells (b), HCT-116 cells (c), and HepG2 cells (d) were analyzed by flow cytometry. Mean fluorescence intensity (MFI) ratio was calculated as MFI with specific mAb/MFI with isotype control mAb (a–d). In the figure, filled white represents the untreated control, filled light gray represents decitabine, filled dark gray represents IR and filled black represents decitabine and IR combination treatment (e). Results are expressed as the average MFI ± SD. Experiments were independently performed from five healthy donors. The assay was performed in triplicated each donor. Statistical significance was determined using a one-way ANOVA. #P < 0.05, ##P < 0.005, ###P < 0.0005 (#DAC 0 versus other groups). **P < 0.005, ***P < 0.0005 (*DAC 5 versus other groups). **P < 0.05, ******P < 0.0005 (**IR versus DAC 5 + IR 8 Gy). @P < 0.05, @@P < 0.005, @@@P < 0.0005 (@DAC 5 versus IR 8 Gy).
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f2: Expression of MHC class I and co-stimulatory molecules in tumor cells after treatment with decitabine, ionizing radiation (IR), or their combination.Tumor cells were treated with 5 μM decitabine for 24 h then exposed to radiation doses of 8 Gy. After 24 h, cells were harvested and the expression of MHC class 1 molecule in various tumor cells (a) and the expression of co-stimulatory molecules in A549 cells (b), HCT-116 cells (c), and HepG2 cells (d) were analyzed by flow cytometry. Mean fluorescence intensity (MFI) ratio was calculated as MFI with specific mAb/MFI with isotype control mAb (a–d). In the figure, filled white represents the untreated control, filled light gray represents decitabine, filled dark gray represents IR and filled black represents decitabine and IR combination treatment (e). Results are expressed as the average MFI ± SD. Experiments were independently performed from five healthy donors. The assay was performed in triplicated each donor. Statistical significance was determined using a one-way ANOVA. #P < 0.05, ##P < 0.005, ###P < 0.0005 (#DAC 0 versus other groups). **P < 0.005, ***P < 0.0005 (*DAC 5 versus other groups). **P < 0.05, ******P < 0.0005 (**IR versus DAC 5 + IR 8 Gy). @P < 0.05, @@P < 0.005, @@@P < 0.0005 (@DAC 5 versus IR 8 Gy).

Mentions: IR and epigenetic modulating agents are known to enhance the expression of several genes in tumor cells, including MHC class I and its co-stimulatory molecules282930313233. Therefore, we investigated whether treatment with decitabine and IR alone or in combination up-regulates MHC class I expression and expression of co-stimulatory molecules in tumor cells. A549, HCT-116, and HepG2 cells were treated with 5 μM decitabine for 24 h. Then, the tumor cells were exposed to radiation doses of 8 Gy. After 24 h, the surface expression of MHC class I, along with co-stimulatory molecules, on tumor cells was analyzed using flow cytometry. As shown in Fig. 2, MHC class I molecules were significantly increased in all target tumor cells treated with decitabine or IR compared with untreated control cells. Furthermore, the combination treatment further significantly increased the expression of MHC class I molecules compared with either treatment alone. In addition, treatment with decitabine or IR significantly increased the expression of co-stimulatory molecules such as CD40 and CD80 in A549 and HCT-116 cells. However, these co-stimulatory molecules were not increased in HepG2 cells treated with decitabine alone. Importantly, the combination treatment further significantly increased the expression of these co-stimulatory molecules compared with either treatment alone. On the other hand, tumor cells treated with decitabine, IR, or their combination did not show changes in CD86 expression levels. These results suggest that treatment with decitabine and/or IR significantly increased the expression of MHC class I and co-stimulatory molecules such as CD40 and CD80. Therefore, the combination treatment may further enhance immunogenicity of tumor cells; however, the effect is dependent on cell type.


Combination treatment with decitabine and ionizing radiation enhances tumor cells susceptibility of T cells
Expression of MHC class I and co-stimulatory molecules in tumor cells after treatment with decitabine, ionizing radiation (IR), or their combination.Tumor cells were treated with 5 μM decitabine for 24 h then exposed to radiation doses of 8 Gy. After 24 h, cells were harvested and the expression of MHC class 1 molecule in various tumor cells (a) and the expression of co-stimulatory molecules in A549 cells (b), HCT-116 cells (c), and HepG2 cells (d) were analyzed by flow cytometry. Mean fluorescence intensity (MFI) ratio was calculated as MFI with specific mAb/MFI with isotype control mAb (a–d). In the figure, filled white represents the untreated control, filled light gray represents decitabine, filled dark gray represents IR and filled black represents decitabine and IR combination treatment (e). Results are expressed as the average MFI ± SD. Experiments were independently performed from five healthy donors. The assay was performed in triplicated each donor. Statistical significance was determined using a one-way ANOVA. #P < 0.05, ##P < 0.005, ###P < 0.0005 (#DAC 0 versus other groups). **P < 0.005, ***P < 0.0005 (*DAC 5 versus other groups). **P < 0.05, ******P < 0.0005 (**IR versus DAC 5 + IR 8 Gy). @P < 0.05, @@P < 0.005, @@@P < 0.0005 (@DAC 5 versus IR 8 Gy).
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f2: Expression of MHC class I and co-stimulatory molecules in tumor cells after treatment with decitabine, ionizing radiation (IR), or their combination.Tumor cells were treated with 5 μM decitabine for 24 h then exposed to radiation doses of 8 Gy. After 24 h, cells were harvested and the expression of MHC class 1 molecule in various tumor cells (a) and the expression of co-stimulatory molecules in A549 cells (b), HCT-116 cells (c), and HepG2 cells (d) were analyzed by flow cytometry. Mean fluorescence intensity (MFI) ratio was calculated as MFI with specific mAb/MFI with isotype control mAb (a–d). In the figure, filled white represents the untreated control, filled light gray represents decitabine, filled dark gray represents IR and filled black represents decitabine and IR combination treatment (e). Results are expressed as the average MFI ± SD. Experiments were independently performed from five healthy donors. The assay was performed in triplicated each donor. Statistical significance was determined using a one-way ANOVA. #P < 0.05, ##P < 0.005, ###P < 0.0005 (#DAC 0 versus other groups). **P < 0.005, ***P < 0.0005 (*DAC 5 versus other groups). **P < 0.05, ******P < 0.0005 (**IR versus DAC 5 + IR 8 Gy). @P < 0.05, @@P < 0.005, @@@P < 0.0005 (@DAC 5 versus IR 8 Gy).
Mentions: IR and epigenetic modulating agents are known to enhance the expression of several genes in tumor cells, including MHC class I and its co-stimulatory molecules282930313233. Therefore, we investigated whether treatment with decitabine and IR alone or in combination up-regulates MHC class I expression and expression of co-stimulatory molecules in tumor cells. A549, HCT-116, and HepG2 cells were treated with 5 μM decitabine for 24 h. Then, the tumor cells were exposed to radiation doses of 8 Gy. After 24 h, the surface expression of MHC class I, along with co-stimulatory molecules, on tumor cells was analyzed using flow cytometry. As shown in Fig. 2, MHC class I molecules were significantly increased in all target tumor cells treated with decitabine or IR compared with untreated control cells. Furthermore, the combination treatment further significantly increased the expression of MHC class I molecules compared with either treatment alone. In addition, treatment with decitabine or IR significantly increased the expression of co-stimulatory molecules such as CD40 and CD80 in A549 and HCT-116 cells. However, these co-stimulatory molecules were not increased in HepG2 cells treated with decitabine alone. Importantly, the combination treatment further significantly increased the expression of these co-stimulatory molecules compared with either treatment alone. On the other hand, tumor cells treated with decitabine, IR, or their combination did not show changes in CD86 expression levels. These results suggest that treatment with decitabine and/or IR significantly increased the expression of MHC class I and co-stimulatory molecules such as CD40 and CD80. Therefore, the combination treatment may further enhance immunogenicity of tumor cells; however, the effect is dependent on cell type.

View Article: PubMed Central - PubMed

ABSTRACT

Decitabine has been found to have anti-metabolic and anti-tumor activities in various tumor cells. Recently, the use of decitabine in combination with other conventional therapies reportedly resulted in improved anti-tumor activity against various tumors. Ionizing radiation (IR) is widely used as a cancer treatment. Decitabine and IR improve immunogenicity and susceptibility of tumor cells to immune cells by up-regulating the expression of various molecules such as major histocompatibility complex (MHC) class I; natural-killer group 2, member D (NKG2D) ligands; and co-stimulatory molecules. However, the effects of combining decitabine and IR therapies are largely unknown. Our results indicate that decitabine or IR treatment upregulates MHC class I, along with various co-stimulatory molecules in target tumor cells. Furthermore, decitabine and IR combination treatment further upregulates MHC class I, along with the co-stimulatory molecules, when compared to the effect of each treatment alone. Importantly, decitabine treatment further enhanced T cell-mediated cytotoxicity and release of IFN- &gamma; against target tumor cells which is induced by IR. Interestingly, decitabine did not affect NKG2D ligand expression or NK cell-mediated cytotoxicity in target tumor cells. These observations suggest that decitabine may be used as a useful immunomodulator to sensitize tumor cells in combination with other tumor therapies.

No MeSH data available.


Related in: MedlinePlus