Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cytogenetically visible gene amplification structures can consist of arrays of amplicons presumably formed by secondary "rearrangements" following amplicon formation. The structural evolution of gene amplification sites in tumor cells suggests that complex secondary structures may have some selective advantage in the tumor cell environment. Although secondary amplicon rearrangements are a hallmark of the gene amplification process, little is known about the mechanics of this process. COLO320 neuroendocrine tumor cells carry two different types of amplified MYC oncogene sequences, one type with an intact MYC gene and the other with a rearranged "chimeric" MYC gene. We have studied various clonal subpopulations of COLO320 cells and identified regions within and downstream of the MYC locus that are unique to each amplicon type. Using double-label fluorescence in situ hybridization with DNA probes unique to each amplicon type, we have observed that both chromosomal and extrachromosomal MYC amplicon arrays in COLO320 cells frequently consist of heterogeneous mixtures of each MYC amplicon type. Our results suggest that the two MYC amplicon types of COLO320 cells were formed simultaneously but independently, and that double minute chromosomes observed in COLO320 cells were formed by intermolecular homologous recombination secondary to amplicon formation.
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PMID:Recombination between separate MYC amplification structures in COLO320 cells. 768 5

Transgenic mice carrying hybrid constructs made by hormone gene promoters attached to viral oncogene sequences proved extremely valuable to investigate the regulatory potency of hormone gene 5' regions. These transgenic mice heritably develop tumors from hormone-producing cells and offer excellent opportunities for studying oncogenesis in the neuroendocrine system. Here the histology of neuroendocrine tumors of three transgenic mice strains (AVP/SV40; RIP1Tag2/RIP2PyST1; GLU2/Tag) is reviewed, preneoplastic lesions are described and tumor development morphology is reconstructed. Transgenic mice experiments provide unique tools for expanding our knowledge of neuroendocrine tumor histogenesis.
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PMID:Characterisation of neuroendocrine tumors in transgenic mice. 769 34

An extract of a neuroendocrine tumor of the human pancreas contained a high concentration of insulin and the C-peptide of proinsulin, as determined by radioimmunoassay, together with somatostatin, calcitonin, and thymosin beta 4. Analysis of the molecular forms of the proinsulin-derived peptides by high-performance liquid chromatography demonstrated that insulin was stored in the tumor as the intact peptide. In contrast, metabolites of C-peptide, representing the (1-21), (1-23), (1-25) and (1-29) N-terminal fragments, were isolated from the extract in addition to intact C-peptide. Generation of these metabolites involves cleavage of Xaa-Leu or Leu-Xaa bonds. Previous immunohistochemical studies have identified cathepsin B in secretory granules and lysosomes of human insulinoma cells. Synthetic human C-peptide was rapidly cleaved by purified human cathepsin B, primarily at the site of leucine residues, to give several metabolites, including the (1-25) and (1-23) fragments. The data indicate that the C-peptide of proinsulin is selectively metabolized in the neoplastic B cell by a mechanism that involves proteolytic cleavages in the C-terminal region of the peptide.
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PMID:Intracellular degradation of the C-peptide of proinsulin, in a human insulinoma: identification of sites of cleavage and evidence for a role for cathepsin B. 771 41

This study aims to examine the frequency of the pheochromocytoma (pheo), defined as a "benign, intra-adrenal, hypertensive, sporadic, unilateral tumor." Three large series amounting to 310 subphrenic chromaffin tumors operated over periods of 17, 23, and 41 years, respectively, have been reviewed. Among those combined 310 pheos, 48 (15.5%) were malignant (i.e., metastatic) and 262 (84.5%) were benign; 42 (13.5%) were ectopic (35% of malignant tumors versus 9.5% of benign tumors); 230 (74.2%) were hypertensive (74% of benign tumors versus 73% of malignant tumors); 29 (9.4%) were bilateral, including 23 patients with a family history; 41 (13.2%) of patients had MEN II type A or B syndrome; and 20 (6.5%) occurred in a phacomatosis setting. Some of the patients had a non-MEN family history of pheo (n = 5), seemingly sporadic hyperparathyroidism (n = 4), or other associated neuroendocrine tumor (n = 9). Sometimes several of these features were combined. Finally 125 (40.3%) cases fitted the classic description of the tumor, 47.0% at the time of initial presentation and 40.3% at the end of follow-up. Late occurrence of metastases or metachronous diagnosis of familial disease make lifelong follow-up mandatory. Genetic studies may be indicated in pheochromocytoma patients.
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PMID:"The" pheochromocytoma: a benign, intra-adrenal, hypertensive, sporadic unilateral tumor. Does it exist? 772 30

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor of the thyroid C-cells. MTC may arise as a sporadic tumor or as a component of one of three autosomal dominant familial cancer syndromes, MEN 2A, MEN 2B, or familial MTC. Recent studies have identified mutations of the RET proto-oncogene in the proximal long arm of chromosome 10, which are thought to be causative for these syndromes. To facilitate the search for other genes involved in the development of MTC, we characterized cytogenetically three human MTC cell lines and three rat MTC cell lines. The human cell lines studied were TT and RO-H85-1, previously reported, and an uncharacterized cell line, MZ-CRC-1, derived from a malignant pleural effusion from a patient with metastatic MTC. The rat MTC cell lines characterized were CA-77, 6-23C6, and 44-2. Cytogenetic abnormalities present in the human and rat cell lines were compared with 13 reported cytogenetic studies of human MTC tumors and three other cytogenetically analyzed MTC cell lines. The human 9q/rat 3 and human 3p/rat 15 chromosomes were affected in six of the comparable cell lines and tumors. These findings suggest human chromosome regions 9q and 3p may contain genes involved in the pathogenesis of MTC.
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PMID:Cytogenetic characterization of three human and three rat medullary thyroid carcinoma cell lines. 773 32

Major hepatic resection is the treatment of choice in patients with primary and secondary liver cancer. During a 22-month period 31 men and 27 women (mean age 63 years, range 14-84) with space-occupying hepatic lesions were admitted. All 15 patients with benign lesions were operated, except for 3 in whom a liver abscess was drained percutaneously. Of the 43 with malignant liver lesions, 30 had liver metastasis secondary to colorectal cancer, 15 of whom underwent major, anatomical and nonanatomical, liver resection and 1 had cryoablation of the tumor. 9 had hepatocellular carcinoma, 1 of whom had a 4-segment non-anatomical resection and 1 tumor cryoablation. 2 with metastasis from a neuroendocrine tumor had anatomical resection of liver lobes. Of 2 with liver metastasis secondary to breast cancer, 1 underwent resection. CT portography, intraoperative ultrasonography and intraarterial injection of Lipiodol were found to be very useful in selecting patients for liver resection.
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PMID:[Primary and metastatic hepatic cancer: the surgical option]. 775 Aug 13

Somatostatin receptor scintigraphy (SRS) is positive in approximately 80% of all patients who have been found to have neuroendocrine (NE) gastroenteropancreatic (GEP) tumors. The reasons for negative results are unclear. The aim of the present study was identification of the specific somatostatin receptor (SSTR) subtypes that are responsible for the in vivo binding of the widely used somatostatin (SST) analogues octreotide and lanreotide in human neuroendocrine gastroenteropancreatic tumors. Ten patients were subjected to SRS with radiolabeled octreotide. Following surgical resection, tumor tissues were analyzed for SSTR subtype mRNA expression by the reverse transcription-polymerase chain reaction (RT-PCR). In addition, SSTR subtype transcripts were investigated by Northern blot analysis and RT-PCR in neuroendocrine tumor cell lines. Expression of SSTR at the protein level was studied by chemical cross-linking experiments. Three patients were negative by SRS. However, RT-PCR revealed most prominently SSTR 2 expression in all tumor specimens. In addition, all tumor tissues analyzed by chemical crosslinking exhibited SST-14 binding sites, indicating that at least some NE tumors were false-negative on SRS.
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PMID:Somatostatin receptor subtypes in neuroendocrine tumor cell lines and tumor tissues. 776 Jun 56

The present immunochemical study concerns the distribution of calcineurin (CaN), a Ca2+/calmodulin-regulated protein phosphatase, in the nervous and neuroendocrine systems of mammals, and discloses the CaN-immunostaining results of human neoplasms. CaN immunoreactivity (ir) was present throughout the nervous system with a marked regional variation in strength of the staining intensity. Light microscopic observations showed that CaN-ir was localized in neurons, but was not detected in non-neuronal cells including astrocytes. Ultrastructural study also revealed that CaN-ir was present only in neuronal elements such as somata, dendrites including postsynaptic densities and spines, and nerve terminals. CaN-ir was also detected in neuroendocrine cells of some endocrine tissues including the pineal gland, pituitary gland, adrenal grand, pancreas and thyroid gland. Immunostaining results of 107 surgical specimens of human neoplasms, including 9 cases of peripheral tumors, disclosed that CaN-immunopositive tumor cells were found to be present in the neuronal tumors including neuroblastomas, ganglioglioma, ganglioneuroma, ganglioneuroblastoma, retinoblastomas, medulloblastomas and central neurocytomas. Also, some neuroendocrine tumors, such as pineocytomas, olfactory neuroblastomas and paragangliomas, specifically reacted for anti-CaN antibody. On the basis of these immunochemical findings, we have proposed that CaN can be a marker protein for detection of neuronal and neuroendocrine tumor cells in the diagnostic pathology of human neoplasms.
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PMID:Immunostaining for calcineurin, a Ca2+/calmodulin-regulated protein phosphatase, in the diagnostic tumor pathology. 779 26

A case of histologically and ultrastructurally confirmed acinar-cell carcinoma of the pancreas examined by needle aspiration cytology is reported. The aspirate showed isolated and loosely clustered cells with variable granular cytoplasm, and central or eccentrically located oval hyperchromatic nuclei displaying prominent nucleoli, suggesting a pancreatic neuroendocrine tumor. Numerous intracytoplasmic zymogen granules and several microtubules within cisternae of rough endoplasmic reticulum (MCRER) were found by electron microscopic study of metastatic tumor tissue. Cytodiagnostic pitfalls of this rare pancreatic cancer are discussed as well as the diagnostic value of MCRERs.
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PMID:Needle aspiration cytology of acinar-cell carcinoma of the pancreas: report of a case with diagnostic pitfalls and unusual ultrastructural findings. 792 11

Merkel cell carcinoma, a neuroendocrine tumor, is a highly invasive cutaneous neoplasm, which rarely affects the eyelids. This tumor must be treated aggressively to minimize the changes of local recurrence and regional or distant metastasis. In this paper, we describe a 78-year-old woman who had two recurrences of this neoplasm after consecutive local excisions. We describe the histopathological findings and emphasize the differential diagnosis with other neoplasms, as the therapeutic approach is different.
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PMID:Merkel cell carcinoma of the eyelid. A clinicopathological case report. 795 55


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