In addition to the known function in the glycolytic pathway, phosphoglycerate kinase 1 (PGK‐1) promotes reduction of plasmin disulfide bonds leading to angiostatin formation and inhibition of tumor angiogenesis. In this study, the effects of PGK‐1 on anti‐ tumor immunity against lung cancer were evaluated using the Tet‐Off control of PGK‐1 expression in the Lewis lung carcinoma (LLC‐1). There was no significant difference in cell proliferation between parental LLC‐1 and LLC‐1 transduced with PGK‐1 (PGK‐LLC‐1). However, expression of PGK‐1 was found to limit tumor growth in mice subcutaneously injected with the cell lines and tumor growth was restored after doxycycline treatment. In addition, the cell invasion ability of PGK‐LLC‐1 became weaker than that of LLC‐1. Expressions of COX‐2, TGF‐β1 and PGE2 were all found to be down‐regulated in PGK‐LLC‐1. PGK‐LLC‐1 cells treated with doxycycline recovered their COX‐2 protein expression. In the presence of conditioned medium from PGK‐LLC‐1, the endothelial cell migration was reduced. Moreover, PGK‐LLC‐1 also stimulated T lymphocytes to express higher levels of Th1 cytokine (IFN‐γ) and lower levels of IL‐10 in comparison with parental LLC‐1. PGK‐LLC‐1 cells restored the growth rate in immunodeficient mice when compared with the growth rate in normal mice. In the tissue sections, reduced COX‐2 expressions and marked infiltrated CD3 T lymphocytes were observed in the PGK‐LLC‐1 injected group. These findings indicate that overexpression of PGK‐1 in LLC‐1 reduces the COX‐2 expression, and, in turn, affect PGE2, cell invasion, angiogenesis, and the immune functions, and finally inhibit the tumor progression. © 2008 Wiley‐Liss, Inc.

Triggering receptor expressed on myeloid cell (TREM) proteins are a family of receptors that regulate many different cell processes. TREM-like transcript 2 (TLT-2) is one of these TREM proteins. It have been reported that TLT-2 plays important roles in inflammation and T cell activation, but it is still elusive in its signal transduction in the cell. In an attempt to identify the active ingredient of Reishi (Ganoderma lucidum) for potential drug development, we isolated a high molecular weight polysaccharide fraction, F3, and performed a comprehensive analysis of its immunomodulatory and adjuvant activities. It was found that this polysaccharide extract had potent immunomodulatory and adjuvant activities in vivo and in vitro. F3-treated mice showed an increase in the number of dendritic cells as well as CD4, CD8, regulatory T, B, plasma, NK, and NKT cells in the spleen. F3 also elevated the levels of twelve cytokines and chemokines in the blood of mice. F3 displayed potent adjuvant activity for tetanus toxoid in the absence of alum and potentiated antibody responses to alum-containing tetanus toxoid in mice. In addition, F3 also boosted Th1 and Th2 response in vivo. In vitro, F3 induced the maturation of dendritic cells derived from human monocytes by upregulating CD40, CD54, CD80, CD83, CD86, and HLA-DR, enhanced mixed lymphocyte reaction and increased the production of sixteen cytokines and chemokines. In microarray analysis, expressions of 7,688 genes were modulated in dendritic cells after treatment with F3, including cytokine and chemokine genes. To ascertain the possible receptors of F3 on human DCs, neutralizing antibodies against TLR-4 and TREM-like transcript 2 (TLT-2), but not TLR-2 and DC-SIGN, partially blocked F3-induced cytokine and chemokine release. TLT-2 and TLR-4 neutralizing antibodies or siRNA of TLT-2 also suppressed F3-induced phosphorylation of ERK1/2 in DCs. Moreover, inhibitors of NF-κB, p38 MAPK and Akt, but not JNK, suppressed F3-induced upregulation of surface markers and reduced F3-induced cytokine production in DCs. F3 and LPS also enhanced phosphorylation of ERK1/2 and TNF-α expression through Raf-MEK signaling cascade and involvement of signaling pathway was validated through the use of specific inhibitors for Raf-MEK- ERK pathway in TLT-2 transfected U937, confirming our observations in DCs. We further demonstrated the expression of Blimp-1 in dendritic cells and its upregulation by F3. The latter could be blocked by TLT-2 antibody. These results provide insight into the TLT-2 mediated signal transduction and immunomodulatory mechanisms of F3 polysaccharide. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 316.