ABSTRACT
<p><b>BACKGROUND</b>Semi-mature dendritic cells (DCs) may induce tolerance rather than immunity. However, little is known about the regulatory mechanism by which these DCs induce transplant tolerance. Myeloid differentiation factor 88 (MyD88) is a key adaptor of Toll-like receptor signaling, which plays a critical role in DC maturation. Activation of MyD88-silenced immature DCs results in the generation of semi-mature DCs. We explored the possibility of using these DCs to induce intestinal transplant tolerance in rats.</p><p><b>METHODS</b>MyD88 expression was silenced in bone marrow DCs (F344 rats) using small interfering RNAs for 24 hours, at which point, lipopolysaccharide (LPS) was added to the culture for another 48 hours. These cells were analyzed for their in vitro and in vivo tolerizing capacities.</p><p><b>RESULTS</b>Semi-mature DCs expressing moderate levels of MHC class II and low levels of co-stimulatory molecules were found to produce interleukin (IL)-10, while IL-12 production was decreased. In vitro co-culture with completely allogeneic T cells from Wistar rats led to a significant decrease in alloreactive T-cell responses. In vivo, the transfer of semi-mature DCs (1 × 10(6) cells) followed by the transplantation of fully mismatched intestinal grafts (F344 rats) led to significantly prolonged survival compared to rats receiving immature and mature DCs. Serum from semi-mature DC-treated rats contained lower concentrations of the pro-inflammatory cytokines IL-2 and interferon-γ 5 days after transplantation.</p><p><b>CONCLUSION</b>Semi-mature DCs may promote inducible allograft tolerance and this study suggests a new strategy by which to facilitate the induction of transplant tolerance.</p>
Subject(s)
Animals , Male , Rats , Blotting, Western , Bone Marrow Cells , Cell Biology , Cell Proliferation , Dendritic Cells , Cell Biology , Metabolism , Enzyme-Linked Immunosorbent Assay , Intestines , Transplantation , Myeloid Differentiation Factor 88 , Genetics , Metabolism , Polymerase Chain Reaction , Rats, Inbred F344 , T-Lymphocytes , Metabolism , Transplantation, Homologous , MethodsABSTRACT
<p><b>BACKGROUND</b>Vascular endothelial growth factor plays a key role in human colorectal carcinoma invasion and metastasis. However, the regulation mechanism remains unknown. Recent studies have shown that several cytokines can regulate the expression of vascular endothelial growth factor in tumor cells. In this study, we investigated whether hepatocyte growth factor can regulate the expression of vascular endothelial growth factor in colorectal carcinoma cells.</p><p><b>METHODS</b>Hepatocyte growth factor and vascular endothelial growth factor in human serum were measured by ELISA. The mRNA level of vascular endothelial growth factor was analyzed by reverse transcription-PCR. Western blot assay was performed to evaluate levels of c-Met and several other proteins involved in the MAPK and PI3K signaling pathways in colorectal carcinoma cells.</p><p><b>RESULTS</b>Serum hepatocyte growth factor and vascular endothelial growth factor were significantly increased in colorectal carcinoma subjects. In vitro extraneous hepatocyte growth factor markedly increased protein and mRNA levels of vascular endothelial growth factor in colorectal carcinoma cells. Hepatocyte growth factor induced phosphorylation of c-Met, ERK1/2 and AKT in a dose-dependent manner. Specific inhibitors on MEK and PI3K inhibited the hepatocyte growth factor-induced expression of vascular endothelial growth factor in colorectal carcinoma cells.</p><p><b>CONCLUSION</b>This present study indicates that hepatocyte growth factor upregulates the expression of vascular endothelial growth factor in colorectal carcinoma cells via the MEK/ERK and PI3K/AKT signaling pathways.</p>
Subject(s)
Humans , Butadienes , Pharmacology , Cell Line, Tumor , Chromones , Pharmacology , Colorectal Neoplasms , Metabolism , Pathology , Gene Expression Regulation , Hepatocyte Growth Factor , Blood , Pharmacology , MAP Kinase Signaling System , Physiology , Morpholines , Pharmacology , Nitriles , Pharmacology , Phosphatidylinositol 3-Kinases , Physiology , Phosphorylation , Proto-Oncogene Proteins c-met , Metabolism , RNA, Messenger , Signal Transduction , Physiology , Vascular Endothelial Growth Factor A , GeneticsABSTRACT
<p><b>OBJECTIVES</b>To evaluate the efficacy of antitumour colon cancer cell vaccine modified by escherichia coli cytosine deaminase (EC-CD).</p><p><b>METHODS</b>Mouse colon cancer cell vaccine CT26/CD was established by gene modification using retrovirus plasmid pLCDSN. Its tumorigenicity and effect on liver metastasis model established with wild-type colon cancer were evaluated.</p><p><b>RESULTS</b>CT26/CD was established successfully and proliferated in medium containing 0.6 g/L G418 stably. EC-CD gene expression on these mutant cells was confirmed by RT-PCR. These mutant cells were more sensitive to 5-fluorocytosine (5-FC) compared with the wild-type ones (P=0.000), and presented excellent bystander effect. CT26/CD had the same tumorigenicity as its parental cells (P=0.892). CT26/CD, combined with the prodrug 5-FC, could inhibit tumor progress and live metastasis, and prolonged the survival of the liver metastasis model animals (P=0.000).</p><p><b>CONCLUSION</b>The colon cancer cell vaccine modified by EC-CD presented anti-tumor effect in vivo, when treated with the prodrug.</p>