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At least 253 records · Page 14Linked to original sources
PubMed2001

The basement membrane-type heparan sulfate proteoglycan (perlecan) in ameloblastomas: its intercellular localization in stellate reticulum-like foci and biosynthesis by tumor cells in culture.

The localization and biosynthesis of basement membrane-type heparan sulfate proteoglycan (HSPG), known as perlecan, were studied in ameloblastomas using surgical tissue sections and cells in primary culture to demonstrate the existence of extracellular matrix (ECM) molecules in the intercellular space of epithelial tissue. HSPG was immunolocalized in the intercellular spaces of stellate reticulum-like cells and small vacuolar structures between basal cells in tumor cell nests as well as in myxofibrous stroma. By means of in-situ hybridization, mRNA signals for the HSPG core were intensely demonstrated in the cytoplasm of basal and parabasal cells of parenchyma. Furthermore, the in-vitro biosynthesis of HSPG core protein by ameloblastoma cells was confirmed using immunofluorescence, immunoprecipitation, and reverse-transcriptase polymerase chain reaction (RT-PCR). The results indicated that ameloblastoma cells synthesize HSPG and deposit it in their intercellular space. The intercellular HSPG might act as a carrier for transport of nutrients to tumor cells within ameloblastomatous foci.

Ameloblastoma↗
PubMed2002

Occurrence of nuclear beta(II)-tubulin in cultured cells.

Microtubules are cylindrical organelles that play critical roles in cell division. Their subunit protein, tubulin, is a target for various antitumor drugs. Tubulin exists as various forms, known as isotypes. In most normal cells, tubulin occurs only in the cytosol and not in the nucleus. However, we have recently reported the finding of the beta(II) isotype of tubulin in the nuclei of cultured rat kidney mesangial cells. Mesangial cells, unlike most normal cell lines, have the ability to proliferate rapidly in culture. In efforts to determine whether nuclear beta(II)-tubulin occurred in other cell lines, we examined the distribution of the beta(I), beta(II), and beta(IV) mammalian tubulin isotypes in a variety of normal and cancer human cell lines by immunofluorescence microscopy. We have found that, in the normal cell lines, all three isotypes are present only in the cytoplasm. However, the beta(II) isotype of tubulin is located not only in the cytoplasm, but also in the nuclei of the following cell lines: LNCaP prostate carcinoma, MCF-7, MDA-MB-231, MDA-MB-435, and Calc18 breast carcinoma, C6 and T98G glioma, and HeLa cells. In contrast, the beta(I) and beta(IV) isotypes, which are also synthesized in cancer cells, are not localized to the nucleus but are restricted to the cytoplasm. We have also seen beta(II) in breast cancer excisions. In most of these cells, beta(II) appears to be concentrated in the nucleoli. These results suggest that transformation may lead to localization of beta(II)-tubulin in cell nuclei, serving an as yet unknown function, and that nuclear beta(II) may be a useful marker for detection of tumor cells.

Adenocarcinoma↗
PubMed2002

Detection of serum MMPs in tumor-bearing hamsters.

BACKGROUND/PURPOSE: Matrix metalloproteinases (MMPs) have been implicated as playing an important role in cancer invasion and metastasis. MMPs have been identified in various malignancies, including pancreatic duct adenocarcinomas. METHODS: We investigated the circulating level of MMP-2 and MMP-9 in sera from Syrian golden hamsters into which hamster pancreatic duct adenocarcinoma tissues had been transplanted subcutaneously (HPDt hamsters). Northern blot analysis and gelatin zymographic analysis were performed to detect the expression of MMPs and that of tissue inhibitors of metalloproteinases (TIMPs) in HPDt hamsters. RESULTS: Northern analysis revealed overexpression of MMP-2, MMP-9, and TIMP-2 mRNAs in subcutaneous tumors of HPDt hamsters as compared with normal pancreatic tissue. Sera from HPDt hamsters possessed significantly higher levels of serum MMP-2 and MMP-9 than control sera, as determined by gelatin zymographic analysis, and there was a significant correlation between tumor growth and serum MMP levels. CONCLUSIONS: These results indicate that overexpression of MMP mRNAs is involved in the progression of pancreatic duct adenocarcinomas, and that MMP protein expression in hamster sera is associated with the presence of pancreatic duct adenocarcinoma cells. The findings also suggest that serum MMPs could be useful markers for monitoring patients with pancreatic duct adenocarcinomas.

Adenocarcinoma↗
PubMed2006

Epigallocatechin gallate induced apoptosis in Sarcoma180 cells in vivo: mediated by p53 pathway and inhibition in U1B, U4-U6 UsnRNAs expression.

The aim of this study was to understand the mode of action of tea polyphenol epigallocatechin gallate (EGCG) in vivo. Swiss albino mice were treated i.p. with EGCG at two different doses i.e. 12-mg/kg body weight and 15-mg/kg body weight, for 7 days prior to inoculation of Sarcoma180 (S180) cells and continued for another 7 days. The growth of the S180, harvested 7 days after inoculation, was significantly reduced due to treatment with EGCG. The flowcytometric analysis of S180 cells, showed significant increase in apoptosis and reduction in the number of cells in G2/M phase of cell cycle due to treatment with EGCG. The induction of apoptosis has also been confirmed by the TUNEL and DNA fragmentation assays. Both RT-PCR and Western blot analysis showed significant up-regulation of p53 and bax, and down-regulation of bcl-2 and c-myc due to EGCG treatment. No changes in the expression pattern of p21, p27, bcl-xl, mdm2 and cyclin D1 were seen. Interestingly, there was significant down-regulation of spliceosomal uridylic acid rich small nuclear RNAs (UsnRNAs) U1B and U4-U6 due to EGCG treatment. This indicates that these UsnRNAs may be involved in the apoptosis process. Taken together, our study suggests that in vivo EGCG could induce apoptosis in S180 cells through alteration in G2/M phase of the cell cycle by up-regulation of p53, bax and down-regulation of c-myc, bcl-2 and U1B, U4-U6 UsnRNAs.

Animals↗
PubMed2006

Hypoxia increases VEGF-A production by prostate cancer and bone marrow stromal cells and initiates paracrine activation of bone marrow endothelial cells.

Hypoxia develops at sites of rapid cancer growth near sites of poorly organized vasculature. Heparin binding growth factors (HBGFs) support neoangiogenesis of tumors. We examined the effect of culturing bone-targeted, metastatic C4-2B prostate cancer cells and bone stromal derived HS27a cells under hypoxic conditions on expression of vascular endothelial growth factor (VEGF) family members. A sealed chamber infused with 1% (hypoxic) or 20% (normoxic) O(2) was used. Both cell lines produced VEGF-A in normoxia, but little or no HB-EGF, another HBGF. HS27a cells produced low levels of FGF-2 and HGF, but little or none was secreted by C4-2B cells. Levels of VEGF-A in conditioned medium (CM) from both cell lines doubled when cultured in hypoxia. Similar changes in VEGF-A mRNA levels were seen. Receptor expression was unchanged by hypoxia. Changes in VEGF-A expression during hypoxia were preceded by nuclear accumulation of hypoxia inducible factor-1alpha (HIF-1alpha). Bone marrow endothelial (BME) cells express high levels of VEGFR2/flk-1, and are targets of VEGF-A induced neovascularization. BME cells proliferated in response to treatment with HS27a CM, but not C4-2B CM. BME cells formed tube-like angiogenic structures on growth factor reduced Matrigel in response to CM from HS27a or C4-2B cells. This response was greater when CM was produced under hypoxia, and was reduced by VEGF-A or FGF-2 neutralizing antibodies. We conclude that hypoxia triggers a physiologically relevant increase in VEGF-A by prostate cancer and bone marrow stromal cells which involves a paracrine loop that recruits and activates BME to support tumor neovascularization-related processes.

Bone Marrow Cells↗
PubMed1981

Isolation of surface lectins of GH3 cells from whole cells and isolated plasma membranes.

Lectins localized in the plasma membranes seem to be of special importance for the intercellular interaction mechanisms. We describe the isolation of mannose-binding proteins by Triton X-100 extraction and affinity chromatography on agarose-bound mannose. The isolation procedure was performed with whole GH3 cells as well as with isolated plasma membranes. For the isolation of plasma membranes of GH3 cells a mechanical pump was used for the disruption. After differential centrifugation an enriched plasma membrane fraction was achieved by discontinuous sucrose gradient centrifugation. The whole fractionation procedure was controlled by total balance sheets for the marker enzymes of the different cell organelles. The plasma membrane fraction was further characterized by gel electrophoresis and electron microscopy. The SDS gel electrophoresis patterns of the proteins, resulting from the Triton X-100 extraction and the affinity chromatography, are nearly identical for whole cells as well as for the enriched plasma membrane fraction. Therefore we presume these mannose-specific proteins to be plasma membrane bound, showing the molecular properties of integral proteins and having a molecular weight of Mr 67 000, 57 000, 47 000.

Animals↗