Influence of dexamethasone and 1,25-Dihydroxyvitamin D on Walker carcinosarcoma 256 growth and parathyroid hormone-related protein secretion.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
F Raue
Publications and source records attributed to F Raue.
Expression of a calcium-sensing receptor in a human medullary thyroid carcinoma cell line and its contribution to calcitonin secretion.
An extracellular Ca(2+)-sensing mechanism consisting of a G protein-coupled receptor linked to phosphoinositide turnover and inhibition of PTH secretion, has recently been identified in bovine parathyroid cells. In C cells, voltage-dependent L-type calcium channels are thought to be involved in calcium-sensing mechanisms, but evidence exists for additional calcium-sensing mechanisms, such as via a calcium-sensing receptor (CaSR). Using the human medullary C cell carcinoma cell line TT, which lacks L-type calcium channels, we found that Ca2+ or cations specific for the CaSR lead to the release of calcium ions from intracellular stores and to an increase in calcitonin secretion. By molecular cloning we isolated the complete protein-coding complementary DNA of a CaSR from human TT cells, which are derived from a human medullary thyroid carcinoma. The CaSR is derived from the same CaSR gene expressed in the parathyroid gland. In addition, TT cells contain an alternative receptor form of CaSR, CaSRb. These findings provide strong evidence for the presence of a functional CaSR in the human C cell line TT. This receptor contributes not only to the inhibition of PTH secretion in the parathyroid, but also to the stimulation of calcitonin secretion in C cells.
Amino Acid Sequence↗
Mutations of the ret protooncogene in German multiple endocrine neoplasia families: relation between genotype and phenotype. German Medullary Thyroid Carcinoma Study Group.
It has been suggested that not only the position but also the nature of the mutations of the ret protooncogene strongly correlate with the clinical manifestation of the multiple endocrine neoplasm type 2 (MEN 2) syndrome. In particular, individuals with a Cys634-Arg substitution should have a greater risk of developing parathyroid disease. We, therefore, analyzed 94 unrelated families from Germany with inherited medullary thyroid carcinoma (MTC) for mutation of the ret protooncogene. In all but 1 of 59 families with MEN 2A, germline mutations in the extracellular domain of the ret protein were found. Some 81% of the MEN 2A mutations affected codon 634. Phenotype-genotype correlations suggested that the prevalence of pheochromocytoma and hyperparathyroidism is significantly higher in families with codon 634 mutations, but there was no correlation with the nature of the mutation. In all but 1 of 27 familial MTC (FMTC) families, mutations were detected in 1 of 4 cysteines in the extracellular domain of the ret protooncogene. Half of the FMTC mutations affected codon 634. Mutations outside of codon 634 occurred more often in FMTC families than in MEN 2A families. In all but 1 of 8 MEN 2B patients, de novo mutations in codon 918 were found. These data confirm the preferential localization of MEN 2-associated mutations and the correlation between disease phenotype and the position of the ret mutation, but there was no correlation between the occurrence of hyperparathyroidism or pheochromocytoma and the nature of the mutation.
Amino Acid Sequence↗
Diagnosis and management of pheochromocytomas in patients with multiple endocrine neoplasia type 2-relevance of specific mutations in the RET proto-oncogene.
It has been suggested that specific mutations in the RET proto-oncogene correlate with clinical manifestation of the multiple endocrine neoplasia type 2 (MEN 2) syndrome. We retrospectively analyzed 61 patients with MEN 2, 28 with associated pheochromocytoma, regarding the relevance of specific mutations in the RET proto-oncogene and the diagnostic sensitivity of catecholamine screening and localization procedures. The present study shows that the position of the RET mutation is related to disease phenotype; codon 634 mutations are predictive of families predisposed to pheochromocytoma. In 18% of our patients, the diagnosis of pheochromocytoma preceded detection of medullary thyroid carcinoma. Therefore, mutation analysis of the RET gene should be performed in apparently "sporadic" cases of pheochromocytoma to confirm or exclude MEN 2. The most sensitive biochemical marker for pheochromocytoma in MEN 2 is 24-h urinary epinephrine excretion. Computed tomography, magnetic resonance imaging and MIBG scintigraphy are all highly sensitive methods to localize pheochromocytoma. We conclude that, in all families with MEN 2, mutational analysis of the RET proto-oncogene should be performed, both to identify gene carriers for MEN 2 and to identify specific mutations that are more strongly associated with pheochromocytoma.
Adult↗
[Bone metabolism and disorders].
Explore the source record for details and available documents.
Adolescent↗
External radiotherapy of pituitary adenomas.
PURPOSE: To evaluate therapeutic outcome and side effects of radiotherapy in pituitary adenomas as sole or combined treatment. METHODS AND MATERIALS: Retrospective analysis of 138 patients (74 male, 64 female) irradiated for pituitary adenoma from 1972 to 1991 was performed. Mean age was 49.7 years (15-80 years). Regular follow-up (in the mean 6.53 +/- 3.99 years) included radiodiagnostical [computed tomography (CT), magnetic resonance imaging (MRI), x-ray], endocrinological, and ophthalmological examinations. Seventy patients suffered from nonfunctional pituitary adenoma, 50 patients suffered from growth-hormone producing adenomas, 11 had prolactinomas, and 7 patients had adrenocorticotropic hormone (ACTH) producing pituitary adenomas. In 99 patients surgery was followed by radiotherapy in case of suspected remaining tumor (invasive growth of the adenoma, assessment of the surgeon, pathologic CT after surgery, persisting hormonal overproduction). Twenty-three patients were treated for recurrence of disease after surgery and 16 patients received radiation as primary treatment. Total doses from 40-60 Gy (mean: 45.5 Gy) were given with single doses of 2 Gy 4 to five times a week. RESULTS: Tumor control was achieved in 131 patients (94.9%). In seven patients, recurrence of disease was diagnosed in the mean 2.9 years (9-98 months) after radiotherapy and salvaged by surgery. A statistically significant dose-response relationship was found in favor of doses > or = 45 Gy. Ninety percent of the patients with hormonally active pituitary adenomas had a benefit from radiotherapy in means of complete termination (38%) or at least reduction (52%) of hormonal overproduction. Partial or complete hypopituitarism after radiotherapy developed, depending on hormonal axis, in 12 (prolactin) to 27% (follicle-stimulating hormone FSH) of patients who had not already had hypopituitarism prior to radiation. Two out of 138 patients suffered reduction of visual acuity, which was, in part, related to radiotherapy. Both therapeutic effects and side effects occurred after a latency period of 3 months up to 9 years. CONCLUSION: We conclude that radiotherapy of pituitary adenomas, using modern treatment planning techniques, is effective and safe. To achieve optimal tumor control, doses of 45-48 Gy (conventionally fractionated) should be applied.
Adenoma↗
Crucial role of c-myc in 1,25(OH)2D3 control of C-cell-carcinoma proliferation.
1,25(OH)2D3 (1,25D3) enhances DNA synthesis and cell proliferation in the human C-cell carcinoma cell line (TT). These effects are dependent on previous stimulation of c-myc gene expression. Since the TT cell line has lost some characteristic C-cell features, we investigated the rat rMTC 6-23 line to assess whether the 1,25D3 effects on TT cells are representative of C-cell carcinoma cells. Addition of 1,25D3 (10(-7)M) led to a 2.5-fold stimulation of 3H-thymidine incorporation (3H-T) in TT cells, which was preceded by a 2-fold increase in c-myc mRNA. In contrast, in proliferating nonstimulated rMTC 6-23 cells, c-myc mRNA was undetectable. Upon addition of 1,25D3 to these cells, 3-HT decreased to 70% of control, with no change in c-myc expression. Thus, the stimulatory effect of 1,25D3 in TT cells seems to depend, at least in part, on a c-myc-dependent pathway.
Calcitriol↗
[Therapy of metastatic medullary thyroid gland carcinoma with the somatostatin analog octreotide].
AIM OF THE STUDY: Medullary thyroid carcinoma like other neuroendocrine tumors express somatostatin receptors. PATIENTS AND METHODS: Antisecretory and antiproliferative effects of the long-acting somatostatin analog octreotide should be evaluated in a prospective study in 7 patients with metastasizing medullary thyroid carcinoma. RESULTS: Treatment with octreotide in daily doses between 100 and 1000 micrograms resulted in a remission lasting up to 12 months in 2 of 7 patients. A decrease of tumor marker levels was observed in 2 patients, improvement of diarrhea and a remission of a lymph node metastasis in one of these. CONCLUSION: This minor therapeutic effect may be due to the relatively low density of receptors or with a low affinity of the receptors expressed in medullary thyroid carcinoma to octreotide.
Adolescent↗
Mutation of the RET protooncogene in sporadic medullary thyroid carcinoma.
Medullary thyroid carcinoma (MTC) occurs sporadically or as part of the inherited cancer syndrome multiple endocrine neoplasia (MEN) type 2. In MEN 2A, germline missense mutations are found in one of five cysteine codons within exons 10 and 11 in the extracellular domain of the RET protooncogene. In MEN 2B, germline mutations occur in codon 918 (exon 16) within the catalytic core of the tyrosine kinase domain. To determine if RET mutations similar to those in MEN 2A and 2B play a role in the pathogenesis of sporadic MTC, we analysed 71 sporadic tumours comprising 68 primary tumours and three cell lines, for mutations in RET exons 10, 11, and 16. We found that 23% of sporadic MTC had RET codon 918 mutations, while only 3% had exon 10 mutations, and none had mutations in exon 11. We found no exon 16 mutations in MTC from 14 MEN 2A cases. Thus, exon 10 and 11 mutations, commonly found in familial MTC and MEN 2A, rarely occur in sporadic MTC; somatic mutation of RET codon 918 appears to play a role in the tumourigenesis of a significant minority of sporadic MTC but not MEN 2A tumours. In addition to their biological interest, these findings may have some clinical application in determining whether a patient presenting with isolated MTC is truly sporadic or is part of an inherited cancer syndrome.
Carcinoma, Medullary↗
Effects of passive immunization against parathyroid hormone-related protein: PTHrP is the responsible factor in mediating hypercalcemia in the Walker carcinosarcoma 256 rat model.
The Walker carcinosarcoma (WCS) 256 is a well-characterized rat model of humoral hypercalcemia of malignancy (HHM). We addressed the question of whether parathyroid hormone-related protein (PTHrP) is the factor responsible for mediating HHM in this model. WCS 256 cells were subcutaneously implanted in female rats. We examined the plasma at days 0, 2, 4, 6, and 8. The midregional PTHrP measured by radioimmunoassay (RIA) and the plasma calcium increased significantly. Measuring PTHrP by a two-site immunoradiometric assay (IRMA) showed comparable results. There was a strong positive correlation between plasma calcium and midregional PTHrP (r = 0.85, p < 0.0001). A strong positive correlation between tumor weight and both midregional PTHrP (r = 0.83, p < 0.0001) and plasma calcium (r = 0.87, p < 0.0001) was also found. After surgical removal of the tumor at day 5, both plasma calcium and plasma PTHrP levels fell to within the normal range. Ip administration of native polyclonal antiserum against PTHrP(53-84) led to a significant decrease of plasma calcium. Extracted WCS 256 tumor showed 5-fold increased levels of midregional PTHrP compared with liver. Immunohistochemistry and Western blot were positive for PTHrP. RNA from the WCS 256 tumor was positive for PTHrP whereas liver tissue RNA was negative. WCS 256 cells grown in vitro also secreted PTHrP into the medium. We conclude that PTHrP is synthesized and secreted by WCS 256 and that PTHrP is the factor responsible for mediating hypercalcemia in the WCS 256 rat model.
Analysis of Variance↗
Presymptomatic genetic screening in families with multiple endocrine neoplasia type 2.
Medullary thyroid carcinoma occurs sporadically or as a part of the inherited cancer syndrome multiple endocrine neoplasia (MEN) type 2. The MEN 2 gene has been identified as the RET proto-oncogene on chromosome 10. In MEN 2A, RET mutations are detectable in one of five cysteine codons within exons 10 and 11 and in MEN 2B in codon 918 (exon 16). Direct DNA testing for RET proto-oncogene mutations is the method of first choice in presymptomatic screening of MEN 2 families. Gene carriers should be offered prophylactic thyroidectomy. The process of DNA analysis for RET proto-oncogene mutations is demonstrated in one family with hereditary medullary thyroid carcinoma. RET mutations were detectable in five of the nine family members at risk.
Adult↗
Parathyroid hormone-related peptide and 8701-BC breast cancer cell growth and invasion in vitro: evidence for growth-inhibiting and invasion-promoting effects.
It has been previously reported that 8701-BC cells, derived from a primary carcinoma of the breast, constitutively express parathyroid hormone-related peptide (PTHrP) gene and that N-terminal PTHrP immunoreactivity can be found in cell medium. Here we have firstly measured immunoreactive PTHrP in 8701-BC cell medium using antibodies raised against midregion and C-terminal fragments, and also demonstrated the expression of PTH/PTHrP receptor by 8701-BC cells. Secondly, we have examined the role, if any, elicited by diverse PTHrP domains on 8701-BC cell proliferation, and invasive behaviour in vitro related to production of extracellular proteolytic enzymes. Our data show that PTHrP [1-34], and, to a minor extent, [67-86] and [107-139], are anti-mitogenic but 'invadogenic' for 8701-BC cells, and suggest that diverse enzymatic activities may contribute to cell invasion in response to different PTHrP fragments. In light of the present data on a chemoattractive role for PTHrP in vitro, we hypothesize that this protein might intervene in local control of the invasive process in breast carcinoma.
Base Sequence↗
Presymptomatic DNA screening in families with multiple endocrine neoplasia type 2 and familial medullary thyroid carcinoma.
BACKGROUND: Missense mutations of the ret proto-oncogene on chromosome 10q11.2 are the underlying cause of hereditary medullary thyroid carcinoma (MTC), either as familial MTC only (FMTC) or as a part of multiple endocrine neoplasia type 2 syndrome (MEN 2). This study presents our experience with direct presymptomatic DNA screening in MEN 2 and FMTC kindreds. METHODS: Twenty one families with MEN 2 or FMTC were considered in the study. One hundred three individuals had been analyzed; 56 were at risk. The ret mutations were detected by DNA analysis of exons 10, 11, and 16 by using nonradioactive labeling method based on digoxigenin DNA sequencing technique. Serum calcitonin evaluation was carried out in all individuals at risk. Thyroidectomy was performed in those who had to undergo surgery. RESULTS: The ret mutations were identified in all 21 families. In MEN 2A and FMTC families mutations occurred in exons 10 and 11. MEN 2B families had mutations in exon 16. The most frequent mutation in MEN 2A and FMTC affected codon 634. Twenty one gene carriers were identified in unaffected individuals at risk. Ten of 21 gene carriers had elevated calcitonin levels, and 11 had normal levels. MTC or C-cell hyperplasia was found in six gene carriers with pathologic calcitonin values who underwent operation. In a 5-year-old gene carrier with normal calcitonin values C-cell hyperplasia was evident. CONCLUSIONS: Direct predictive DNA analysis allows us to identify MEN 2 or FMTC gene carriers and offer them prophylactic treatment.
Base Sequence↗
Microsurgical neck dissection for metastasizing medullary thyroid carcinoma.
Surgery is the only accepted method for a potentially curative treatment of metastatic medullary cancer of the thyroid (MCT). Between 5/1988 and 2/94 53 patients (mean age 43, 14-65 years) were treated. A total of 24 patients underwent surgery of both sides of the neck whereas 29 patients required only one side. Six months after surgery, a profound reduction in basal serum calcitonin levels (CT) was detected in all patients. Upon pentagastrin stimulation, CT levels remained suppressed in eight patients. A pathological increase of normalized basal CT values was noted in 33 patients. In 12 patients, basal CT concentrations remained elevated after surgery. We conclude that metastatic MCT can be effectively treated by microsurgical modified radical neck dissection.
Adolescent↗
Clinical significance of antibodies against calcitonin.
Calcitonin (CT) inhibits osteoclast-mediated bone resorption and is being used to treat Paget's disease of bone, hypercalcemia of malignancy and postmenopausal osteoporosis. The formation of antibodies against heterologuous calcitonins like salmon calcitonin (sCT) is common and occurs in 40-70% of the patients treated for more than 4 months. Not all of these patients, however, develop a secondary resistance to sCT, therefore the clinical significance of sCT antibodies is discussed controversially. In vivo and in vitro approaches demonstrate a neutralizing effect in 35 to 60% of the patient sera with antibodies against sCT. These neutralizing antibodies appear to explain most cases of clinically relevant secondary resistance to sCT treatment, which occurs in 25-45% of the patients after treatment periods of 6 months and longer. A positive treatment response to human CT after development of secondary resistance to sCT proves the diagnosis of antibody related resistance. Few cases develop secondary resistance in the absence of sCT binding antibodies, the mechanism of this phenomenon is unclear. Antibody related resistance is a significant problem in long term treatment with sCT. Especially in conditions like postmenopausal osteoporosis, where no readily accessable marker of treatment response is available, the development of sCT antibodies and their possible neutralizing effect has to be considered.
Animals↗
Adenosine A1-receptors inhibit cAMP and Ca2+ mediated calcitonin secretion in C-cells.
The effect of the adenosine A1 receptor activation on calcitonin secretion was studied in medullary thyroid carcinoma cells of the rat (rMTC 6-23). Calcitonin was determined by radioimmunoassay, intracellular cAMP by protein binding assay, intracellular calcium in fura-2 loaded single cells using microspectrofluorimetry, and calcium channel activity by patch clamp technique. The adenosine A1 receptor analogue N-6 phenylisopropyl-adenosine (PIA) (10(-10)-10(-6) M) inhibits dose-dependently glucagon (10(-7) M) and rGRH (10(-7) M) stimulated cAMP formation and calcitonin secretion. These effects were partly abolished by pretreatment with pertussis toxin (PT) (100 ng/ml). PIA (10(-10)-10(-6) M) also suppressed extracellular calcium-stimulated calcitonin secretion, rises in intracellular calcium, and calcium channel currents. PT (100 ng/ml) pretreatment again partly abolished this inhibitory effect. The addition to the medium of adenosine deaminase (0.4 U/ml) stimulated calcitonin secretion. Our results suggest that in calcitonin-secreting cells A1 receptors couple to adenylate cyclase and calcium channels via PT-sensitive G proteins and thus inhibit calcitonin secretion. Adenosine seems to act as an autocrine/paracrine factor in calcitonin-secreting cells.
Adenosine↗
Evaluation of somatostatin as a plasma tumor marker in medullary thyroid carcinoma.
Somatostatin (SRIF) immunoreactivity has been frequently reported in tumor tissues of cell types, belonging to the APUD system, including medullary thyroid carcinoma (MTC). However, the value of SRIF as a plasma tumor marker for MTC is controversial. We have measured SRIF plasma levels in 35 patients with different stages of MTC to evaluate the use of SRIF as a plasma tumor marker compared to the current "gold standard" calcitonin (CT). The median SRIF value in healthy controls was 36.5 pg/mL, the upper limit of normal was defined at the controls. The median value was 28 pg/mL (p = 0.37, Mann-Whitney U test). Five patients in the control group and three in the MTC group had SRIF levels that exceed the 95th percentile. SRIF and CT levels correlated only weakly (0.38), as determined by the Spearman rank order correlation test. Pentagastrin stimulation led to a diagnostic increase in SRIF levels in only one of five MTC patients. During selective venous catheterization, diagnostic gradients for CT, allowing tumor localization, could be demonstrated, whereas measurement of SRIF levels did not aid in tumor detection. Although SRIF immunostaining may be valuable as an additional marker in the histochemical diagnosis of MTC, SRIF has no value as a plasma tumor marker in the diagnosis of this disease.
Adult↗