ABSTRACT
Thrombospondins (TSPs) are angiostatic factors in various cancers. However, the significance of TSPs has not been well characterised in glioma. We examined TSP1, TSP2 and vascular endothelial growth factor (VEGF) gene expression by reverse transcription-polymerase chain reaction (RT-PCR) in 37 gliomas. Thirty of the 37 glioma specimens showed VEGF gene expression. Eighteen of the 37 gliomas expressed the TSP1 gene. Seven gliomas lacked TSP2 gene expression, while the other 30 expressed TSP2. The lack of TSP2 gene expression was significantly associated with higher histological grade (Fisher's test, P = 0.0019) and increased vessel counts and density (Student's t-test, P < 0.0001), while there were no correlations between TSP1 and VEGF gene expression and clinicopathological features. These results indicate that the lack of TSP2 gene expression is a potent factor for enhancement of angiogenesis in glioma.
Subject(s)
Glioma/blood supply , Glioma/metabolism , Neoplasm Proteins/metabolism , Thrombospondins/metabolism , Adult , Analysis of Variance , Animals , Endothelial Growth Factors/metabolism , Female , Gene Expression , Glioma/genetics , Humans , Lymphokines/metabolism , Male , Mice , Mice, SCID , Middle Aged , Neoplasm Proteins/genetics , Neoplasm Transplantation , Neovascularization, Pathologic , Reverse Transcriptase Polymerase Chain Reaction/methods , Thrombospondins/genetics , Vascular Endothelial Growth Factor A , Vascular Endothelial Growth FactorsABSTRACT
If activation of the p53 gene is involved in the progression or metastasis of colon cancer, it may affect the angiogenic phenotype in vivo. To verify this hypothesis, we studied the correlation between p53 accumulation and expression of thrombospondin-1 (TSP1) in colon cancer specimens. Levels of TSP1 gene expression were estimated by Northern blotting in 65 colon cancers. Accumulation of p53 and the distribution of TSP1 protein were evaluated immunohistochemically. Various levels of TSP1 gene expression were seen in colon cancers, while p53 accumulation was confirmed in 42 of the 65 colon cancers. The level of TSP1 gene expression demonstrated a significant inverse correlation with p53 accumulation in colon cancer. Colon cancer cells expressed TSP1 protein and p53 accumulation reciprocally in the same nests. These results suggest that alterations in the tumour suppressor gene p53 may inhibit TSP1 expression in colon cancer.
Subject(s)
Adenocarcinoma/genetics , Colonic Neoplasms/genetics , Gene Expression Regulation, Neoplastic , Genes, p53/genetics , Thrombospondin 1/genetics , Adenocarcinoma/metabolism , Adenocarcinoma/pathology , Aged , Blotting, Northern , Colonic Neoplasms/metabolism , Colonic Neoplasms/pathology , DNA Primers/chemistry , DNA, Neoplasm/analysis , Female , Humans , Immunoenzyme Techniques , Male , Middle Aged , Mutation , Thrombospondin 1/metabolism , Tumor Suppressor Protein p53/metabolismABSTRACT
The present study was an attempt to elucidate the effect of estrogenic xenobiotics on the proliferation of mitogen-stimulated human peripheral blood lymphocyte (PBL). Our findings follow: (a) the proliferation of PBL in response to phytohemagglutinin (PHA) was mediated by protein kinase C activity, but estrogenic xenobiotics had a strong inhibitory effect on protein kinase C activity of PHA-stimulated PBL; (b) cytoplasmic extracts from PHA-stimulated PBL greatly activated DNA replication, but estrogenic xenobiotics had a strong inhibitory effect on these activities. The results suggest that the cytoplasmic signal-generating system in mitogen-treated PBL is inhibited by estrogenic xenobiotics, and that the defect occurs at all stages in the sequence of events leading to DNA synthesis and cell proliferation.
Subject(s)
Estradiol Congeners/pharmacology , Lymphocyte Activation/drug effects , Lymphocytes/drug effects , Signal Transduction/drug effects , Xenobiotics/pharmacology , Adult , Cells, Cultured , DNA Replication/drug effects , Estradiol/pharmacology , Female , Humans , Lymphocytes/enzymology , Lymphocytes/metabolism , Protein Kinase C/metabolismABSTRACT
Human glioma usually shows intrinsic multidrug resistance because of the blood-brain barrier (BBB), in which membrane-associated P-glycoprotein (P-gp), encoded by the human multidrug resistance gene MDR1, plays a role. We studied drug sensitivity to vincristine (VCR), doxorubicin (DOX) and nimustine (ACNU) in both intracerebrally and subcutaneously xenotransplanted human glioma. We examined the levels of MDR1 and murine mdr3 gene expression in the xenografts by reverse transcriptase polymerase chain reaction and the localization of P-gp by immunohistochemistry. Six of seven subcutaneously transplanted xenografts (scX) were sensitive to the above three drugs. In contrast, all three intracerebrally transplanted human glioma xenografts (icX) were resistant to P-gp-mediated drugs VCR and DOX, but were sensitive to the non-P-gp-mediated drug ACNU. Neither icX nor scX showed any MDR1 expression. Intracerebrally transplanted human glioma xenografts showed an increased level of murine mdr3 gene expression, whereas scX showed only faint expression. The localization of P-gp was limited to the stromal vessels in icX by immunohistochemistry, whereas scX expressed no P-gp. Our findings suggest that the P-gp expressed on the stromal vessels in icX is a major contributing factor to multidrug resistance in human glioma in vivo.