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NK-cell-dependent killing of colon carcinoma cells is mediated by natural cytotoxicity receptors (NCRs) and stimulated by parvovirus infection of target cells.

Bhat R, Rommelaere J - BMC Cancer (2013)

Bottom Line: We show that IL-2-activated human NK cells can effectively kill colon carcinoma cells.The cytotoxicity of NK cells towards colon carcinoma cells, both mock- and H-1PV-infected, was found to be mostly mediated by a combination of natural cytotoxicity receptors (NCRs), namely NKp30, 44, and 46.Lysates of H-1PV-infected colon carcinoma cells were found to increase MHC class II expression on dendritic cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: German Cancer Research Center (DKFZ), Tumor Virology, F010, Im Neuenheimer Feld 242, Heidelberg D-69120, Germany. r.bhat@dkfz.de

ABSTRACT

Background: Investigating how the immune system functions during malignancies is crucial to developing novel therapeutic strategies. Natural killer (NK) cells, an important component of the innate immune system, play a vital role in immune defense against tumors and virus-infected cells. The poor survival rate in colon cancer makes it particularly important to develop novel therapeutic strategies. Oncolytic viruses, in addition to lysing tumor cells, may have the potential to augment antitumor immune responses. In the present study, we investigate the role of NK cells and how parvovirus H-1PV can modulate NK-cell mediated immune responses against colon carcinoma.

Methods: Human NK cells were isolated from the blood of healthy donors. The cytotoxicity and antibody-mediated inhibition of NK cells were measured in chromium release assays. Phenotypic assessment of colon cancer and dendritic cells was done by FACS. The statistical significance of the results was calculated with Student's t test (*p <0.05; **, p < 0.01; ***, p < 0.001).

Results: We show that IL-2-activated human NK cells can effectively kill colon carcinoma cells. Killing of colon carcinoma cells by NK cells was further enhanced upon infection of the former cells with parvovirus H-1PV. H-1PV has potent oncolytic activity against various tumors, yet its direct killing effect on colon carcinoma cells is limited. The cytotoxicity of NK cells towards colon carcinoma cells, both mock- and H-1PV-infected, was found to be mostly mediated by a combination of natural cytotoxicity receptors (NCRs), namely NKp30, 44, and 46. Colon carcinoma cells displayed low to moderate expression of NK cell ligands, and this expression was modulated upon H-1PV infection. Lysates of H-1PV-infected colon carcinoma cells were found to increase MHC class II expression on dendritic cells.

Conclusions: Altogether, these data suggest that IL-2-activated NK cells actively kill colon carcinoma cells and that this killing is mediated by several natural cytotoxicity receptors (NCRs) in combination. Additionally, in association with parvovirus H-1PV, IL-2-activated NK cells have the potential to boost immune responses against colon cancer.

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Killing of colon carcinoma cells by IL-2 -activated NK cells and CD8+T cells. Freshly isolated NK cells (Figure 1a-d) and CD8+ T cells (Figure 1e) were cultured with IL-2 (100 U/ml) for one week and used as effector (E) cells in 4-h 51Cr release assays performed on the HT29 (1a), SW480, (1b) Colo32 (1c), and Lovo (1d) cell lines. NK-cell-mediated cell lysis was measured at the indicated E:T ratio. Data are means (with SD bars) of triplicates performed with NK cells from one donor. They are representative of independent experiments performed with material from three different donors.
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Figure 1: Killing of colon carcinoma cells by IL-2 -activated NK cells and CD8+T cells. Freshly isolated NK cells (Figure 1a-d) and CD8+ T cells (Figure 1e) were cultured with IL-2 (100 U/ml) for one week and used as effector (E) cells in 4-h 51Cr release assays performed on the HT29 (1a), SW480, (1b) Colo32 (1c), and Lovo (1d) cell lines. NK-cell-mediated cell lysis was measured at the indicated E:T ratio. Data are means (with SD bars) of triplicates performed with NK cells from one donor. They are representative of independent experiments performed with material from three different donors.

Mentions: In vitro51Cr release assays were performed to test the (heretofore unknown) capacity of NK cells to kill colon carcinoma cells. NK cells isolated from healthy donors were stimulated with IL-2 (100 IU/ml) for a week or two and used as effector cells against 51Cr-labeled target colon carcinoma cells in a 4-h incubation assay. Using an E:T ratio ranging from 5:1 to 20:1, we found NK cells to be potent killers of colon carcinoma cells under these experimental conditions. In assays performed with NK cells from the same donors, the tested cell lines displayed differential susceptibility to killing by NK cells. SW480 and HT29 cells proved to be the most susceptible (Figure 1a, b), whereas Lovo and Colo32 cells showed low to moderate susceptibility (Figure 1c, d). Alloreactive cytotoxic CD8+ T cells from different healthy donors were likewise stimulated with IL-2 (100 U/ml) and tested for cytotoxicity towards colon carcinoma cells. These cells showed only a low level of colon carcinoma cell killing (Figure 1e). We conclude that IL-2-activated NK cells may constitute an effective tool for targeting colon carcinoma cells.


NK-cell-dependent killing of colon carcinoma cells is mediated by natural cytotoxicity receptors (NCRs) and stimulated by parvovirus infection of target cells.

Bhat R, Rommelaere J - BMC Cancer (2013)

Killing of colon carcinoma cells by IL-2 -activated NK cells and CD8+T cells. Freshly isolated NK cells (Figure 1a-d) and CD8+ T cells (Figure 1e) were cultured with IL-2 (100 U/ml) for one week and used as effector (E) cells in 4-h 51Cr release assays performed on the HT29 (1a), SW480, (1b) Colo32 (1c), and Lovo (1d) cell lines. NK-cell-mediated cell lysis was measured at the indicated E:T ratio. Data are means (with SD bars) of triplicates performed with NK cells from one donor. They are representative of independent experiments performed with material from three different donors.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3733944&req=5

Figure 1: Killing of colon carcinoma cells by IL-2 -activated NK cells and CD8+T cells. Freshly isolated NK cells (Figure 1a-d) and CD8+ T cells (Figure 1e) were cultured with IL-2 (100 U/ml) for one week and used as effector (E) cells in 4-h 51Cr release assays performed on the HT29 (1a), SW480, (1b) Colo32 (1c), and Lovo (1d) cell lines. NK-cell-mediated cell lysis was measured at the indicated E:T ratio. Data are means (with SD bars) of triplicates performed with NK cells from one donor. They are representative of independent experiments performed with material from three different donors.
Mentions: In vitro51Cr release assays were performed to test the (heretofore unknown) capacity of NK cells to kill colon carcinoma cells. NK cells isolated from healthy donors were stimulated with IL-2 (100 IU/ml) for a week or two and used as effector cells against 51Cr-labeled target colon carcinoma cells in a 4-h incubation assay. Using an E:T ratio ranging from 5:1 to 20:1, we found NK cells to be potent killers of colon carcinoma cells under these experimental conditions. In assays performed with NK cells from the same donors, the tested cell lines displayed differential susceptibility to killing by NK cells. SW480 and HT29 cells proved to be the most susceptible (Figure 1a, b), whereas Lovo and Colo32 cells showed low to moderate susceptibility (Figure 1c, d). Alloreactive cytotoxic CD8+ T cells from different healthy donors were likewise stimulated with IL-2 (100 U/ml) and tested for cytotoxicity towards colon carcinoma cells. These cells showed only a low level of colon carcinoma cell killing (Figure 1e). We conclude that IL-2-activated NK cells may constitute an effective tool for targeting colon carcinoma cells.

Bottom Line: We show that IL-2-activated human NK cells can effectively kill colon carcinoma cells.The cytotoxicity of NK cells towards colon carcinoma cells, both mock- and H-1PV-infected, was found to be mostly mediated by a combination of natural cytotoxicity receptors (NCRs), namely NKp30, 44, and 46.Lysates of H-1PV-infected colon carcinoma cells were found to increase MHC class II expression on dendritic cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: German Cancer Research Center (DKFZ), Tumor Virology, F010, Im Neuenheimer Feld 242, Heidelberg D-69120, Germany. r.bhat@dkfz.de

ABSTRACT

Background: Investigating how the immune system functions during malignancies is crucial to developing novel therapeutic strategies. Natural killer (NK) cells, an important component of the innate immune system, play a vital role in immune defense against tumors and virus-infected cells. The poor survival rate in colon cancer makes it particularly important to develop novel therapeutic strategies. Oncolytic viruses, in addition to lysing tumor cells, may have the potential to augment antitumor immune responses. In the present study, we investigate the role of NK cells and how parvovirus H-1PV can modulate NK-cell mediated immune responses against colon carcinoma.

Methods: Human NK cells were isolated from the blood of healthy donors. The cytotoxicity and antibody-mediated inhibition of NK cells were measured in chromium release assays. Phenotypic assessment of colon cancer and dendritic cells was done by FACS. The statistical significance of the results was calculated with Student's t test (*p <0.05; **, p < 0.01; ***, p < 0.001).

Results: We show that IL-2-activated human NK cells can effectively kill colon carcinoma cells. Killing of colon carcinoma cells by NK cells was further enhanced upon infection of the former cells with parvovirus H-1PV. H-1PV has potent oncolytic activity against various tumors, yet its direct killing effect on colon carcinoma cells is limited. The cytotoxicity of NK cells towards colon carcinoma cells, both mock- and H-1PV-infected, was found to be mostly mediated by a combination of natural cytotoxicity receptors (NCRs), namely NKp30, 44, and 46. Colon carcinoma cells displayed low to moderate expression of NK cell ligands, and this expression was modulated upon H-1PV infection. Lysates of H-1PV-infected colon carcinoma cells were found to increase MHC class II expression on dendritic cells.

Conclusions: Altogether, these data suggest that IL-2-activated NK cells actively kill colon carcinoma cells and that this killing is mediated by several natural cytotoxicity receptors (NCRs) in combination. Additionally, in association with parvovirus H-1PV, IL-2-activated NK cells have the potential to boost immune responses against colon cancer.

Show MeSH
Related in: MedlinePlus