Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P61278 (somatostatin)
22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two cases of somatostatin (SRIF)-producing medullary carcinoma of the thyroid are presented. The plasma levels of SRIF and calcitonin changed in accordance with the clinical course before and after resection of the tumor. On chromatographic analysis of tumor extracts derived from primary and metastatic tumors of medullary thyroid carcinoma, at least two components of immunoreactive SRIF (IR-SRIF) of large molecular size were found, besides a component corresponding to the tetradecapeptide (SRIF 14); one of these seemed to have almost the same molecular weight as the octacosapeptide (SRIF 28). Most of the IR-SRIF in one patient's plasma was eluted in the same position as tetradecapeptide SRIF. The biological activity of SRIF recovered from the tumor extract was assessed by measuring activity for inhibiting GH release using dispersed rat anterior pituitary cells. GH release from the cells into the incubation medium tended to decrease at a concentration of 1 x 10(-9) M IR-SRIF derived from the tumor (3000 +/- 482 ng/10(5) cells . 3 h) compared with the control value (4288 +/- 567 ng/10(5) cells . 3 h). A significant decrease was observed at concentrations of 1 x 10(-8) M (1880 +/- 403 ng/10(5) cells . 3 h) and 5 x 10(-8) M (938 +/- 262 ng/10(5) cells . 3 h). Responses to equivalent amounts of synthetic SRIF 14 were similar. This suggests that IR-SRIF in the tumor has almost the same biological activity as synthetic tetradecapeptide SRIF.
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PMID:Molecular heterogeneity and biological activity of immunoreactive somatostatin in medullary carcinoma of the thyroid. 611 66

We have constructed and cloned in bacteria complementary DNAs derived from a transplantable rat medullary thyroid carcinoma. Using a hybridization probe encoding an anglerfish islet pre-prosomatostatin, a precursor of the tetradecapeptide somatostatin, we have identified and isolated a clone containing a 400-base pair complementary DNA encoding most of the rat carcinoma pre-prosomatostatin. The amino acid sequence of the tetradecapeptide somatostatin and of the amino-terminally extended form, somatostatin-28 was deduced from the nucleotide sequence of the complementary DNA. Somatostatin-28 was found at the COOH terminus of a polypeptide of at least 80 amino acids indicating that somatostatin-28 arises by cleavage from a large precursor. The sequences of somatostatin-28 and somatostatin-14 are strictly conserved between the rat and other mammals. Such conservation of these sequences indicates strong selective pressures during evolution to maintain the sequence and suggests that somatostatin-28 may serve some essential biologic functions apart from, or in addition to, the important regulatory actions of somatostatin-14. Additionally, we found a high degree of homology in the amino acid sequences of the NH2-terminal extension peptides in the anglerfish islet and the rat carcinoma pre-prosomatostatins pointing further to a possible biologic function of these extension peptides.
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PMID:Somatostatin-28 encoded in a cloned cDNA obtained from a rat medullary thyroid carcinoma. 612 Jan 63

The plasma levels of somatostatin (SRIF) were studied in normal subjects and patients with various disorders by a sensitive and specific radioimmunoassay. In 45 normal subjects, the fasting plasma SRIF concentrations were 13.3 +/- 5.3 pg/ml (mean +/- SD). Very high concentrations of plasma SRIF, ranging from 125.0 pg/ml to 400.0 pg/ml, were found in all four patients with medullary carcinoma of the thyroid examined and the SRIF levels were changed in parallel with their clinical course after resection of the tumor. A case of pheochromocytoma also showed a relatively high SRIF concentration in plasma (47.0 pg/ml), but the plasma SRIF level decreased to 8.7 pg/ml after removal of the tumor. In normal subjects, plasma SRIF levels did not fluctuate during 2 hr-observation period in basal state. Glucagon (1 mg, iv) and secretin (3 CHRU/kg B.W., iv infusion over 30 min) had no effect on the SRIF levels in the peripheral blood plasma of normal subjects. On intravenous infusion of arginine (0.5 g/kg B.W.) over 30 min, all 6 normal subjects showed a significant increase in plasma SRIF 30-45 min after the start of the infusion (basal value, 11.6 +/- 1.5 pg/ml; peak value, 27.2 +/- 3.0 pg/ml; p less than 0.005). Two cases of medullary thyroid carcinoma showed exaggerated responses after the arginine administration (increases of 103 pg/ml and 157 pg/ml, respectively), suggesting that SRIF was released from the tumor. The findings indicate that plasma SRIF determination in the basal state and after arginine administration is useful for detecting and following up SRIF-producing tumors.
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PMID:Plasma somatostatin in normal subjects and in various diseases: increased levels in somatostatin-producing tumors. 612 47

Bilateral medullary carcinoma of the thyroid (MCT) was discovered in a symptomless patient of a high-risk MCT family. Raised serum calcitonin responding abnormally to pentagastrin led to a thyroidectomy. Grossly, the thyroid showed one nodule in the upper third of each lobe. Light microscopy revealed typical MCT with amyloid deposits. Nontumoral thyroid tissue showed C cell parafollicular hyperplasia. Electron microscopy detected intracellular secretory granules (mean diameter, 150 nm) and typical amyloid fibrills. Immunochemistry revealed numerous calcitonin immunoreactive cells in the nodules, in normal para and intrafollicular C-cells and hyperplastic C-cells. Somatostatin and ACTH were detected in certain tumor cells, but not in normal and hyperplastic C-cells. MCT hormonal production potential is discussed.
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PMID:Calcitonin, somatostatin and ACTH immunoreactive cells in a case of familial bilateral thyroid medullary carcinoma. 612 68

Medullary thyroid carcinoma (MTC) is a neoplasm derived from thyroidal C cells. This tumor occurs spontaneously in several animal species and is relatively common in certain strains of rats. Descriptive reports of such neoplasms in mice, however, have not been published. From several studies using female BALB/c mice, 3 animals were identified that had thyroid neoplasms histologically compatible with MTC. All three primary neoplasms and a first generation transplant from one of them contained calcitonin. Somatostatin was identified in two of three primary thyroidal neoplasms and in the first-generation transplant. Ultrastructurally, the neoplastic cells of the first-generation transplant contained membrane-bound dense-core granules that resembled those seen in normal mouse C cells. Intracisternal Type A retrovirus particles were also identified in neoplastic cells in this case. Transplantation of one of the neoplasms yielded subcutaneous masses averaging 2 cm in diameter by 3 months following transplantation in the second-generation recipients. These neoplasms resemble MTCs of man, rat, and other species and may prove of value for comparative morphologic and endocrinologic studies of C cell neoplasms and for studies of factors that regulate the synthesis and secretion not only of calcitonin but also of a variety of regulatory peptides, including somatostatin.
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PMID:Medullary thyroid carcinoma in female BALB/c mice. A report of 3 cases with ultrastructural, immunohistochemical, and transplantation data. 613 Jul 3

In a case study of medullary thyroid carcinoma (MTC) associated with Cushing's syndrome, elevated levels of urinary 17-hydroxycorticosteroids, plasma ACTH, cortisol, calcitonin (CT) and somatostatin (GHRIH) were documented. Lysine vasopressin administration further increased the levels of plasma ACTH, cortisol and CT, whereas the administration of calcium and pentagastrin increased only the level of plasma CT. Immunoreactive ACTH, CT and GHRIH were highly concentrated in the tumour tissues. Basal plasma ACTH levels were more progressively increased than plasma CT during the postoperative course when the patient was treated with o,p'-DDD, since the tumour was not completely resected. These findings suggest that the secretion of ACTH and CT from MTC were regulated in a different manner.
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PMID:Plasma calcitonin and ACTH responses to lysine vasopressin, calcium and pentagastrin in a patient with medullary thyroid carcinoma associated with Cushing's syndrome. 613 58

The tetradecapeptide hormone somatostatin arises from proteolytic processing of a large precursor, pre-prosomatostatin. Studies of other hormone precursors predict that the NH2 terminus of pre-prosomatostatin comprises a leader, or signal, region which is cleaved during its translation. Such co-translational cleavage would generate prosomatostatin. In these studies, we present the complete sequence of rat pre-prosomatostatin, deduced from the nucleotide sequence of cDNAs derived from a somatostatin-rich medullary thyroid carcinoma. These findings indicate that rat pre-prosomatostatin contains 116 amino acids (12,737 daltons). Cell-free translations of medullary thyroid carcinoma mRNA with dog pancreas microsomal membranes were performed to identify the cleavage point of the leader region from prosomatostatin. Partial microsequencing data indicates that the cleavage occurs between the glycine and alanine at positions 24 and 25 of pre-prosomatostatin. Thus, rat prosomatostatin contains 92 amino acids (10,388 daltons). Comparison of the amino acid sequences of the rat and human pre-prosomatostatins reveals only four amino acid substitutions. In view of the high degree of homology between rat and human pre-prosomatostatin, we expect a similar cleavage site and NH2-terminal structure for human prosomatostatin. The high level of conservation between rodents and humans of the entire pre-prosomatostatin molecule further suggests the possibility of biologic functions of the NH2-terminal portions of prosomatostatin.
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PMID:Rat pre-prosomatostatin. Structure and processing by microsomal membranes. 613 71

An undecanucleotide extended hybridization probe has been used to screen a rat medullary thyroid carcinoma cDNA library for clones which contain preprosomatostatin sequences. The nucleotide sequence encoding rat preprosomatostatin is reported. The sequence of cDNA contains 67 nucleotides in the 3'-noncoding region, 84 nucleotides in the 5'-untranslated region, and 458 bases corresponding to the coding region. The mRNA codes for a somatostatin precursor 116 amino acids in length (Mr = 12,773). The preprosomatostatin has a sequence of hydrophobic amino acids at the NH2 terminus, followed by a peptide of approximately 78 residues, which precedes somatostatin-14. The amino acid sequences of rat and human preprosomatostatin (Shen, L. P., Pictet, R. L., and Rutter, W. J. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 4575-4579) differ by only 4 amino acid residues. Translation of rat poly(A) RNA in a rabbit reticulocyte cell-free system followed by immunoprecipitation with antisera directed against somatostatin-14 demonstrated the synthesis of a single protein having a molecular weight of 15,000. Two proteins having molecular weights of 14,000 and 15,000 are immunoprecipitated from a wheat germ cell-free translation mixture. Northern analysis of the somatostatin mRNA indicated that it is approximately 850 nucleotides in length. Analysis of several medullary thyroid carcinomas demonstrated that one tumor, designated WF, had immunoreactive somatostatin-14 in concentrations of 350 ng of somatostatin-14/mg of protein and somatostatin mRNA that represented 10% of the cellular poly(A) RNA. Cell lines derived from this tumor may provide an attractive system to investigate the regulation of somatostatin gene expression.
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PMID:Cloning and characterization of a mRNA-encoding rat preprosomatostatin. 613 33

The predicted amino acid sequence of rat preprosomatostatin has been obtained by cloning and subsequent DNA sequence analysis of a cDNA obtained from mRNA prepared from a rat medullary thyroid carcinoma (MTC). The predicted preprosomatostatin is 116 amino acid residues in length. Somatostatin-14 is located at the C-terminus of the preprohormone and the amino terminus contains a 'signal' peptide of 24 amino acids. A somatostatin amino terminal protein of 78 residues is found between the signal peptide and somatostatin-14. Both somatostatin-14 and somatostatin-28 are observed in the thyroid tumour C-cells. A comparison of the rat and human preprosomatostatin amino acid sequences shows only 4 substitutions observed in 116 amino acids. Patients with localized MTC often exhibit high serum calcitonin levels while patients showing cellular heterogeneity in the MTC appear to have lower calcitonin levels and a virulent neoplasia with a grave prognosis. Numerous rat MTCs have been examined by two dimensional gel electrophoresis. It is possible to distinguish characteristic differences in protein profiles of tumours producing high levels of calcitonin from those showing low calcitonin and high somatostatin levels. This analysis can be done with less than 1 mg of tissue and may represent a valuable prognostic tool in evaluating the clinical variability of MTC.
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PMID:Cloning and biosynthetic studies of rat somatostatin. 613 51

The somatostatins are peptides of 14 and 28 amino acids that are produced in a variety of endocrine and nonendocrine tissues. These peptides inhibit the secretion of many different pituitary, pancreatic, and gastrointestinal hormones. Previously, we have reported the isolation and nucleotide sequence of a cDNA derived from a rat medullary thyroid carcinoma that encoded preprosomatostatin , a 116-amino-acid precursor of somatostatin. We now report the structural characterization of the rat somatostatin gene isolated from recombinant bacteriophage libraries prepared from rat liver DNA. The gene spans 1.2 kilobases and is interrupted within the coding sequence of prosomatostatin by a single intron of 630 bases. A sequence characteristic of a Goldberg- Hogness promoter ("TATA" box), T-T-T-A-A-A-A, is located 31 bases upstream from the transcriptional initiation site. A repetitive DNA sequence, highly reiterated in the rat genome, is located in the 5' flanking region of the gene within 900 bases of the initiation site.
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PMID:Primary structure of the gene encoding rat preprosomatostatin. 614 56


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