Inhibitory effect of dendritic cells combined with cytokine-induced killer cells on the growth and liver metastasis of human primary malignant melanoma of the small intestine

Abstract

Objective To investigate the inhibitory effect of dendritic cells (DCs) and homologous cytokine-induced killer cells (CIKs) on the growth and liver metastasis of human primary malignant melanoma of the small intestine. Methods A histologically intact liver metastasis fragment derived from a surgical specimen of patients with primary malignant melanoma of the small intestine was implanted in the mucous layer of small intestine in nude mice to construct the liver metastasis model of the malignant melanoma. Peripheral blood mononuclear cells from healthy donors and patients with malignant melanoma of the small intestine were isolated. DCs and CIKs were separately produced according to corresponding culture method, and the DC-CIKs were harvested after coculorthotopically implanted in 56 nude mice, and 72 hours later, all the mice were equally divided into normal saline group (0.3 ml), mitomycin treatment group (400 μg/0.3 ml), healthy donor CIK group (6 × 107/0.3 ml),healthy donor DC-CIK group (3 × 107/0.3 ml), autologous CIK treatment group (6 × 107/0.3 ml), autologous DC-CIK group (6 × 107/0. 3 ml) and DC-CIK (6 × 107/0.3 ml) + mitomycin (400 μg/0. 3 ml) treatment group. Mice in the experimental groups were administered the agents once daily by vena caudalis injection for 28 days. Mice were sacrificed 72 hours after treatment, and the orthotopic xenografts were removed for weighing,and the liver metastases were simultaneously evaluated by macroscopy and microscopy. All data were analyzed using the analysis of variance, LSD test and chi-square test. Results A liver metastatic model of human primary malignant melanoma of the small intestine ( HSIM-0603 ) was established. Of the control group, healthy donor CIK group, healthy donor DC-CIK group, autologous CIK treatment group, autologous DC-CIK group and DC-CIK +mitomycin group, the tumor weights were ( 1.18 ± 0. 17), (0.71 ± 0.06), (0.68 ± 0. 15 ), (0. 43 ± 0.08 ),(0.67 ± 0.07 ), (0.37 ± 0.08 ) and (0.20 ± 0.05 ) g, respectively; the tumor inhibition rates were 0, 39.82%,42.37%, 65.56%, 43.22%, 68.64% and 83.05%, respectively; liver metastases were detected in 8, 8, 5,4, 4, 3, 2 rats, respectively, in the above mentioned groups. There were significant differences in the tumor weight, tumor inhibition rate and liver metastasis rate among the seven groups (F = 152. 300, x2= 200. 538,94. 325, P ＜ 0.05 ). Conclusions The liver metastatic model could be applied to the studies on the pathogenesis,invasion, metastasis and treatment of human primary malignant melanoma of the small intestine. DC-CIK has the potential in inhibiting the growth and liver metastasis of the malignant melanoma of the small intestine. Key words: Neoplasms of small intestine; Malignant melanoma; Liver metastasis; Animal model; Dendritic cells; Killer cells; Immunotherapy