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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ultrastructural findings in a sacrococcygeal chordoma are presented. The tumor cells showed various types of vacuoles. The presence of two types of membrane-bound dense bodies and an intracellular fibrillar material were other striking features of the tumor. Most of the present findings are in agreement with other studies and suggest a double differentiation of the tumor cells, epithelial and mesenchymatous. It is believed that the extracellular substance forming the tumor matrix is produced by mature tumor cells. Despite the pleomorphism and the variation of cell components, it is suggested that the stellate, intermediate and physaliferous cells, constitute the same cell at different stages of maturation.
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PMID:[Ultrastructure of a sacral chordoma]. 123 73

The membrane-bound polyribosomes in Ehrlich ascites tumor cells can be separated into a loosely bound and a tightly bound fraction by means of a high salt treatment. Both membrane fractions as well as the free polyribosomes in the supernatant synthesize about the same set of proteins, suggesting a close relationship between these polyribosome fractions in the Ehrlich cell. Relatively high concentrations of cycloheximide do not prevent newly synthesized poly(A)-containing mRNA from entering the tightly bound polyribosome fraction. Nor had treatment of the cells with puromycin in the presence of cycloheximide, which released about 70% of the nascent chains, any significant effect on the entrance of newly synthesized mRNA into tightly bound polyribosomes. These results suggest that in ehrlich ascites tumor cells nascent polypeptide chains are not involved in the binding of polyribosomes to membranes.
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PMID:Transport of messenger RNA into different classes of membrane-associated polyribosomes in Ehrlich-ascites-tumor cells. 123

Nasal neuroblastoma, esthesioneuroblastoma, is frequently difficult to distinguish from the more common poorly differentiated epidermoid carcinoma of the nasal cavity and nasopharynx. We present a simple alternate method to electron microscopy, formaldehyde-fume-induced fluorescence, to demonstrate biogenic amine granules in neoplastic cells. This method is more specific and more sensitive, since it reveals the presence of biogenic amines, not merely membrane-bound granules, and it deals with larger quantities of tissue, thus avoiding some of the sampling errors inherent in electron microscopy. We also describe the histochemical relationship of this tumor to other neural crest neoplasms.
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PMID:Fume-induced fluorescence in diagnosis of nasal neuroblastoma. 124 26

A case of benign clear cell tumor ("sugar tumor") of the lund with extensive necrosis is reported. Electron microscopic study established the diagnosis by virtue of the characteristic cytoplasmic membrane-bound glycogen. Ultrastructural study may be necessary in cases containing necrosis to differentiate this lesion decisively from metastatic renal cell carcinoma.
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PMID:Benign clear cell tumor of lung with necrosis. 126 Jul 21

The first case of benign fibrous histiocytoma of the renal capsule is reported in a male aged 44 years. The tumor had its point of origin in the renal capsule. Histologically, the tumor was composed of intersecting fascicles of fibroblastic cells forming a loose crisscross or "storiform" pattern. Electron microscopic studies of tumor cells revealed intermediate filaments and membrane-bound collagen fibers which continued to extracellular collagen bundles. This deep seated fibrous histiocytoma had a more prominent storiform pattern and fewer secondary elements such as xanthoma cells than cutaneous ones.
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PMID:Benign fibrous histiocytoma of the renal capsule. 131 15

A number of glycoproteins are regulators of the complement cascade and prevent damage to cells by inappropriate activation of complement. In humans, all of them are encoded by a multigene family on chromosome I and share a characteristic structural feature, the short consensus repeats of about 61 amino acids with a constant framework of cysteine, proline, and tryptophan. We found the gene for glycoproteins of analogous structure in herpesvirus saimiri, a T-lymphotropic tumor virus of New World primates. Unspliced transcripts code for a membrane-bound 65- to 75-kDa virion surface component, while spliced mRNA instructs a secreted glycoprotein of 47 to 53 kDa. Expression of complement control proteins suggests a novel mechanism of counteracting host immune defense to prevent elimination of a virus that is capable of persisting in circulating lymphocytes.
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PMID:New member of the multigene family of complement control proteins in herpesvirus saimiri. 131 92

A rare small cell carcinoma with neurosecretory granules arising in an ovarian dermoid cyst with 7 years survival after conservative surgery and adjuvant chemotherapy with cisplatin, adriamycin, and cyclophosphamide is described. Light microscopy showed the typical uniformly small cells with hyperchromic nuclei and scanty basophilic cytoplasm within the mature cystic teratoma. Although none of the immunohistochemical stains were reactive, electron microscopy demonstrated the membrane-bound neurosecretory granules in some tumor cells. The related literature is reviewed and the issues concerning treatment options in this unusual malignancy are discussed.
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PMID:Small cell carcinoma with neurosecretory granules arising in an ovarian dermoid cyst. 132 24

In order to identify potential markers of malignancy in diagnostic respiratory cytopathology, c-myc and c-erbB-2 proto-oncogene expression was studied in fine needle aspirates from 14 consecutive fresh operation tissue samples (after surgical removal) representing lung tumors and a variety of other cell samples by in situ hybridization of 35S-labeled antisense and sense RNA c-myc and c-erbB-2 specific proto-oncogene probes. All 14 lung tumors showed c-myc expression and eight also showed c-erbB-2 expression. On average, the c-myc expression was about 4 times higher than that of c-erbB-2 (P less than 0.001). c-erbB-2 expression, confirmed also as a cytoplasmic membrane-bound reactivity by immunohistochemical stainings for c-erbB-2 oncoprotein, was significantly related to adenocarcinoma (P less than 0.025), whereas increasing tumor size correlated significantly with increasing c-myc expression (P less than 0.05). On average, all the tumor cell lines showed 2-fold expression of c-myc compared with the lung tumors (P less than 0.025). c-erbB-2 expression was found in six of 11 cell lines. High c-myc proto-oncogene expression was also found in broncho-epithelial cells and alveolar macrophages, and a low expression was found in lymphocytes but not in neutrophils, while none of these cells showed c-erbB-2 proto-oncogene expression. Our results demonstrate extensive c-myc proto-oncogene expression in both malignant and non-neoplastic proliferating cells, but not in terminally differentiated cells such as neutrophils. Therefore c-myc expression must also be related to general cell proliferation and not only malignancy per se. In marked contrast, c-erbB-2 proto-oncogene expression was found only in adenocarcinoma cells, and thus can be used as a marker for malignancy in diagnostic respiratory cytopathology.
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PMID:Evidence by in situ hybridization that c-erbB-2 proto-oncogene expression is a marker of malignancy and is expressed in lung adenocarcinomas. 135 55

TNF, a cytokine with cytotoxic activity on a variety of tumor cells, is mainly produced by macrophages; however, some tumor cell types of non-macrophage origin, apparently resistant to TNF-mediated cell lysis, can also produce TNF. It is not clear whether these cells were TNF-resistant a priori or whether protective mechanisms against toxicity of autocrine TNF may be induced in TNF-producing cells. Murine L929sA fibrosarcoma cells, which are highly sensitive to TNF cytotoxicity, were transfected with the neomycin resistance (neor) gene, alone or in combination with the human (h) or the murine (m) TNF gene. All exogenous genes were under control of the constitutive SV40 early promoter. After cotransfection, the number of neor colonies was 10 to 100% as compared with the number of colonies upon transfection with the neor gene alone. An appreciable fraction of these colonies (50-100%) constitutively produced biologically active TNF. mTNF-producing L929 cells were fully TNF resistant, whereas hTNF-producing cells showed partial TNF resistance. Specific TNF binding could not be detected on mTNF-producing L929sA transfectants, whereas hTNF-producing cells showed reduced TNF binding. Apparently, TNF gene expression, even in a priori TNF-sensitive cells, can induce mechanisms to prevent toxicity by both autocrine and exogenous TNF. No TNF resistance was induced by expression of a gene sequence encoding the 9-kDa membrane-bound presequence part of the 26-kDa mTNF proform. Expression of a mutant 26-kDa TNF gene coding for a quasi-inactive mature mTNF induced only weak TNF resistance as compared with the complete resistance obtained after transfection with the wild-type gene. These findings show that the membrane-bound TNF presequence as such is not sufficient for induction of TNF resistance and imply that the active site of mature TNF is involved in modulation of TNF responsiveness upon autocrine TNF production.
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PMID:Expression of an exogenous tumor necrosis factor (TNF) gene in TNF-sensitive cell lines confers resistance to TNF-mediated cell lysis. 137 99

Human stem cell factor (SCF) acts in the presence of other growth factors to stimulate the growth of primitive hematopoietic progenitor cells. These effects are performed by activation of the SCF receptor, c-kit. Because of the potential use of SCF in patients undergoing chemotherapy and bone marrow transplantation, the effect of SCF on nonhematopoietic tumors requires investigation. To determine whether human tumor cell lines display c-kit receptors, we performed binding experiments with 125I-SCF on a breast carcinoma cell line (Du4475), a gastric carcinoma cell line (KATO III), a melanoma cell line (HTT144), as well as two small cell lung carcinoma cell lines (H69 and H128). The biologic effect of SCF on tumor cell lines was assessed by its ability to stimulate tritiated thymidine uptake and to enhance colony growth in methylcellulose. The breast carcinoma cell line, Du4475, as well as two small cell lung carcinoma cell lines, H69 and H128, exhibit high-affinity c-kit receptors with approximate binding affinities of 40, 100, and 90 pmol/L, respectively. The number of high-affinity receptors per cell ranged from 700 to 9,500. The gastric carcinoma cell line, as well as the melanoma cell line, showed trace binding of 125I-SCF. In the presence of SCF alone, or in combination with granulocyte-macrophage colony-stimulating factor or interleukin-3, there was less than a 17% increase in the colony growth of Du4475, H69, or H128 cell lines. Postulating that the lack of growth response could be secondary to endogenous SCF production by the tumor cell lines, we used an RNAse protection assay to determine whether the tumor cell lines contain SCF messenger RNA (mRNA). In addition, we tested tumor cell line supernatants for the presence of secreted SCF protein by enzyme immunoassay, and analyzed the tumor cell lines for membrane-bound SCF by indirect immunofluorescence. Our results show that the Du4475, H69, and H128 cell lines, as well as a melanoma cell line (HTT144), have multiple copies of SCF mRNA. Soluble SCF protein was detected in the cell supernatants in the Du4475 and H69 cell lines and SCF was found on the surface of all four cell lines. These data show that some human solid tumor cell lines display high-affinity c-kit receptors and produce SCF, which can be detected on the cell surface. These results suggest the possibility that autocrine production of SCF by c-kit receptor-bearing tumor cells may enhance cell growth in tumor cell lines.
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PMID:Nonhematopoietic tumor cell lines express stem cell factor and display c-kit receptors. 137 16


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