Inhibition of human pancreatic tumor growth by cytokine-induced killer cells in nude mouse xenograft model

Abstract

Pancreatic cancer is the fourth commonest cause of cancer-related deaths in the world. However, no adequate therapy for pancreatic cancer has yet been found. In this study, the antitumor activity of cytokine-induced killer (CIK) cells against the human pancreatic cancer was evaluated in vitro and in vivo. Human peripheral blood mononuclear cells were cultured with IL-2-containing medium in anti-CD3 for 14 days. The resulting populations of CIK cells comprised 94% CD3(+), 4% CD3(-)CD56(+), 41% CD3(+)CD56(+), 11% CD4(+), and 73% CD8(+). This heterogeneous cell population was called cytokine-induced killer (CIK) cells. At an effector-target cell ratio of 100:1, CIK cells destroyed 51% of AsPC-1 human pancreatic cancer cells, as measured by the (51)Cr-release assay. In addition, CIK cells at doses of 3 and 10 million cells per mouse inhibited 42% and 70% of AsPC-1 tumor growth in nude mouse xenograft assays, respectively. This study suggests that CIK cells may be used as an adoptive immunotherapy for pancreatic cancer patients.

Keywords: Adoptive immunotherapy; Cytokine-induced killer cells; Pancreatic cancer.

Figure 1

The phenotypes of CIK cells. Human PBMCs were cultured in the presence of IL-2 and anti-CD3 antibody for 14 days and the resulting CIK cell populations were stained with human monoclonal antibodies, such as anti-CD3-FITC plus anti-CD56-PE (A), anti-CD4-FITC plus anti-CD8-PE (B).

Figure 2

The in vitro cytotoxicity of CIK cells. Human PBMCs were cultured in the presence of IL-2 and anti-CD3 antibody for 14 days and the resulting CIK cell populations were used to examine cytotoxicity to K562 (A) and AsPC-1 (B). These target cells were labeled with ⁵¹Cr and incubated for 4 h with CIK cells at effector-to-target ratios of 1-100:1.

Figure 3

Inhibition of AsPC-1 tumor growth by CIK cells in nude mouse xenograft models. Nude mice (n=7) were implanted subcutaneously with nine million AsPC-1 cancer cells. CIK cells at doses of 1 (CIK 1), 3 (CIK 3), and 10 (CIK 10)×10⁶ cells/mouse were injected intravenously once a week. Adriamycin (ADR) was injected intravenously at 2 mg/kg. Tumor volumes were estimated by the formula: length (mm)×width (mm)×height (mm)/2 (A). On day 20, the mice were sacrificed and the tumor weights were measured (B). Representative photographs are shown (C). Statistical significance was determined using the ANOVA test versus PBS-treated control group (^*p<0.05, ^**p<0.01).

Figure 4

Body weight changes of tumor-bearing nude mice. Nude mice (n=7) were implanted subcutaneously with nine million AsPC-1 cancer cells. CIK cells at doses of 1 (CIK 1), 3 (CIK 3), and 10 (CIK 10)×10⁶ cells/mouse were injected intravenously once a week. Adriamycin (ADR) was injected intravenously at 2 mg/kg. The body weights of the tumor-bearing nude mice were measured to estimate toxicity.