High mobility groupbox-1 (HMGB1) is a multifunctional cytokine secreted by cancer cells, which accelerates cell growth, invasion and angiogenesis in cancer, and induces apoptosis in macrophages. Thioglycolate-stimulated mouse peritoneal macrophages were induced to differentiate into dendritic cells by co-treatment with IL-4 and GM-CSF. The number of mouse peritoneal macrophage-derived dendritic cells (PMDDCs) showed a dose-dependent decrease in hrHMGB1 treatment. HMGB1-treated PMDDCs showed obvious apoptosis and increased the level of phosphorylated JNK. Intraperitoneal administration of HMGB1 decreased CD205-positive splenic dendritic cells in C57BL mice. To confirm the HMGB1-induced inhibitory effect on dendritic cells, 16 cases of human colon cancer invaded into the subserosal layer were examined. The 8 nodal metastasis-positive cases showed higher nodal HMGB1 concentrations (74 ± 23 vs. 41 ± 15 μg/ml, p = 0.0116) in lymph node tissues and lower CD205-positive nodal dendritic cell numbers (86 ± 22 vs. 137 ± 43/mm², p = 0.0224) than those in the 8 metastasis-negative cases. Primary tumor tissues of metastasis-positive cases showed higher tumor HMGB1 levels (116 ± 33 vs. 37 ± 18 μg/ml, p = 0.0007) and lower CD205-positive intratumoral dendritic cell numbers (21 ± 13 vs. 62 ± 23 /mm², p = 0.0068) than those in metastasis-negative cases. These findings suggest that HMGB1 produced by colon cancer cells suppressed nodal dendritic cells to disturb host anti-cancer immunity.

CD10 expression is associated with metastases of colorectal cancer (CRC). In the present study, we examined association of CD10 with liver metastasis of CRC cells to clarify the therapeutic significance of CD10. CD10-positive human colon cancer cell line, HT29 cells showed inhibition of growth, invasion and colony formation by treatment with CD10 antisense S-oligodeoxynucleotide (S-ODN). In the mouse liver metastasis mode, CD10 antisense S-ODN-treated HT29 cells made less embedded cells in the liver than control HT29 cells. Number and size of metastatic foci in nude mice liver were reduced in CD10 antisense S-ODN-treated HT29 cells. Treatment with CD10 antisense S-ODN decreased phosphorylation of ERK1/2 and EGFR in HT29 cells. Intraperitoneal administration of liposome-capsulated CD10 antisense S-ODN inhibited establishment of liver metastasis and growth of established metastasis in nude mice. These findings suggest that CD10 is associated substantially with liver metastasis of CRC cells and might be a molecular target of CRC treatment.

I n CRC, the anticancer immunity of the host is suppressed due to the secretion of several cytokines. High-mobility group box 1 protein induces apoptosis of macrophages (1) to reduce tumorassociated macrophages, which enhances metastasis of CRC. (4,5) These factors cause the escape of cancer cells from host immunity, thereby enhancing disease progression and metastasis. In the present study, we focused on MENK as an immune-evasion factor in CRC.Methionine-enkephalin is a neuropeptide known to exhibit opium-like effects on the central nervous system. Morphine affects the immune system and inhibits cellular immunity. (6) Opioids alter the second messenger cyclic adenosine monophosphate, intracellular calcium, and kinases activated by second messengers in immune cells. (7,8) Similar to morphine, MENK is an immunomodulator that modifies immune responses to extracellular stimuli such as mitogens and antigens.(9) DOR, the specific receptor of MENK, is expressed in T lymphocytes.(9) In some situations, opiates induce apoptosis of T lymphocytes through the JNK pathway.(10) MENK is produced in high concentrations in colon cancer.(11) We therefore hypothesized that MENK produced by CRC cells suppresses T lymphocytes so that the cells escape the effects of the host's anticancer immunity. In the present study, we examined the effect of MENK on T lymphocytes in vitro and in human CRC materials to test the hypothesis. Materials and MethodsCell culture and reagents.

We explored the mechanism through which patients sometimes show immunosuppression after cardiac surgery. To test the hypothesis that commonly used drugs could cause apoptosis of immune cells, the proapoptotic effects of heparin and catecholamines (dopamine and dobutamine) on peripheral blood lymphocytes were evaluated. Peripheral blood lymphocytes were purified from blood samples of normal healthy volunteers. These cells were cultured in the presence of heparin, dobutamine or dopamine. The apoptosis was quantified by Annexin V fluorescent assay, by DNA content and by morphological assessment. Lymphocytes did not show significant levels of apoptosis induction after 24 hours of incubation with heparin. Both dopamine and dobutamine demonstrated a clear apoptosis inducing effect on lymphocytic population after 24 and 48 hours of culture, in concentrations comparable with the clinically used levels. Apoptosis was time and concentration dependent for both catecholamines. The dopamine and dobutamine effect on lymphocyte viability was due, at least partially, to lymphocyte beta receptor engagement, as proved by blocking the receptor with propranolol. These results suggest that catecholamines could induce apoptosis of lymphocytes. This finding may be associated with immunosuppression observed in patients undergoing cardiac surgery.