bluuebunny/crossref_metadata_2025 huggingface dataset:
Resistance to different antiestrogens is caused by different multi-factorial changes and is associated with reduced expression of IGF receptor Ialpha.
Authors: Brockdorff B L , Heiberg I , Lykkesfeldt A E
Published: December 2004

Development of antiestrogen resistance is a major clinical problem, and therefore it is crucial to elucidate the mechanisms involved. To investigate whether gain-of-function or loss-of-function mechanisms was most likely to be involved, cell fusion between the antiestrogen-sensitive MCF-7 and the ICI 164384- and ICI 182780-resistant MCF-7/164(R)-5 cell lines was performed. Furthermore, a fusion cell line between the tamoxifen-resistant MCF-7/TAM(R)-1 and the MCF-7/164(R)-5 cell line was established. A thorough investigation of growth parameters and expression of selected proteins (estrogen receptor-alpha (ERalpha), progesterone receptor (PR), Bcl-2, IGF-binding protein-2 (IGFBP2) and IGF receptor Ialpha (IGF-IRalpha)) in the fusion partners and fusion cells revealed that both gain- and loss-of-function changes occurred, and that the mechanisms resulting in resistance to the two antiestrogens were different. This multi-factoriality of antiestrogen resistance is promising in relation to sequential treatment of breast cancer patients with different types of endocrine therapy. Furthermore, we found an association between antiestrogen resistance and reduced IGF-IRalpha expression. Overall, the data presented in this report support the usefulness of cell fusion to clarify the mechanisms involved in development of resistance to the pure antiestrogens ICI 182780 and ICI 164384 and the selective ER modulator tamoxifen and suggest IGF-IRalpha as a new sensitive marker for response to antiestrogen treatment.
The gene expression profiling of sporadic pheochromocytoma and novel full-length cDNAs cloning.
Authors: Yang Y-S , Song H-D , Peng Y-D , Huang Q-H , Li R-Y , Zhu Z-D , Hu R-M , Han Z-G , Chen J-L
Published: December 2004

Pheochromocytoma is a chromaffin cell neoplasm that typically causes symptoms and signs of episodic catecholamine release. Pheochromocytoma can be divided into two types: familial and sporadic. The molecular mechanisms involved in familial pheochromocytoma have been unraveled, but the detailed molecular mechanism of sporadic pheochromocytoma remains unknown. The present study thus aimed at characterization of gene expression profiling of sporadic pheochromocytoma using expressed sequence tags (ESTs), and established a preliminary catalog of genes expressed in the tumor. In total, 4115 ESTs were generated from the tumor library. The gene expression profilings of the pheochromocytoma and the normal adrenal gland were compared, and 341 genes were identified to be significantly expressed differently between the two libraries. Interestingly, 16 known genes participating in cell division or apoptosis were notably differently expressed between the tumor and the normal adrenal gland. Twenty-four novel full-length cDNAs were cloned from the tumor library and five of them were significantly up-regulated in the tumor. Some of them may be involved in the tumorigenesis of pheochromocytoma. The sequence data of ESTs and novel full-length cDNAs described in this paper have been submitted to the GeneBank library.
Neuroendocrine tumours.
Authors: Barakat M T , Meeran K , Bloom S R
Published: December 2004

Neuroendocrine tumours are a heterogeneous group including, for example, carcinoid, gastroenteropancreatic neuroendocrine tumours, pituitary tumours, medullary carcinoma of the thyroid and phaeochromocytomas. They have attracted much attention in recent years, both because they are relatively easy to palliate and because they have indicated the chronic effect of the particular hormone elevated. As neuroendocrine phenotypes became better understood, the definition of neuroendocrine cells changed and is now accepted as referring to cells with neurotransmitter, neuromodulator or neuropeptide hormone production, dense-core secretory granules, and the absence of axons and synapses. Neuroendocrine markers, particularly chromogranin A, are invaluable diagnostically. Study of several neuroendocrine tumours has revealed a genetic etiology, and techniques such as genetic screening have allowed risk stratification and prevention of morbidity in patients carrying the particular mutation. Pharmacological therapy for these often slow-growing tumours, e.g. with somatostatin analogues, has dramatically improved symptom control, and radiolabelled somatostatin analogues offer targeted therapy for metastatic or inoperable disease. In this review, the diagnosis and management of patients with carcinoid, gut neuroendocrine tumours, multiple endocrine neoplasia types 1 and 2, and isolated phaeochromocytoma are evaluated.
Management of risk of breast carcinoma in postmenopausal women.
Authors: Biglia N , Defabiani E , Ponzone R , Mariani L , Marenco D , Sismondi P
Published: December 2004

Breast carcinoma is the most frequent tumor in the female population. Many factors can influence the risk of breast cancer; some of them, such as old age and breast cancer 1/2 (BRCA1/BRCA2) gene mutations, are associated with a fourfold increase in risk. A previous diagnosis of atypical ductal or lobular hyperplasia or having a first-degree relative with a carcinoma are factors associated with a two- to fourfold increase in risk. A relative risk between 1 and 2 is associated with longer exposure to endogenous hormones as a result of early menarche, late menopause and obesity, or with recent and prolonged use of hormone replacement therapy (HRT) or with behavioural factors such as high alcohol and fat intake. Is it possible to modify breast cancer risk in postmenopausal women? Risk factors related to lifestyle can be changed, even if it is not clear whether modifying these behavioural factors during the postmenopausal period will influence the overall breast cancer risk. For instance, the influence of exogenous hormones throughout life (both oral contraceptives and HRT) should be evaluated according to the individual risk-benefit ratio. The problem is even more complex for women who carry genetic mutations and for those who have close relatives with breast cancer, who may be candidates for risk reduction strategies. Prophylactic bilateral mastectomy is still controversial, but is frequently offered to or requested by this group of women and may be indicated in BRCA1/BRCA2 carriers. Chemoprevention with tamoxifen and with the new selective estrogen receptor modulators, namely raloxifene, is very promising and deserves a thorough discussion for all high-risk women.
The interaction of oestrogen receptor status and pathological features with adjuvant treatment in relation to survival in patients with operable breast cancer: a retrospective study of 2660 patients.
Authors: Barnes D M , Millis R R , Gillett C E , Ryder K , Skilton D , Fentiman I S , Rubens R D
Published: December 2004

The oestrogen receptor (ER) status of 2660 patients with primary breast cancer has been related to the effect of different adjuvant systemic therapies on survival. However, as patients in the various treatment groups also had different prognostic features comparison between treatments was difficult. Over 90% of patients receiving tamoxifen (Tam) were postmenopausal compared with <20% of those receiving chemotherapy (CT). The latter had more positive nodes (85% vs 54%) and grade III tumours (54% vs 30%) than the Tam group. The combined CT and Tam group had similar characteristics to the CT alone group. The current reported increase in the proportion of women with ER+ tumours is explained by immunohistochemical analysis of ER and screening programmes. ER status was unrelated to survival in patients with small, low grade, node-negative tumours which was no different from that expected for age-matched women taken from the general population. The value of adjuvant treatment in these patients is therefore questionable. In those given any adjuvant treatment, survival of women with ER+ tumours was prolonged, with the greatest effect being seen in those receiving Tam. Patients with ER- tumours benefited from CT but the addition of Tam to CT improved survival only in those with ER+ tumours. ER status is now established as a major predictive factor for treatment selection in primary disease. Studies of prognostic and predictive markers may be invalidated by use of adjuvant therapy and selection criteria for different treatments. Survival will be influenced by both tumour biology and therapy. This important consideration must be remembered when analysing new markers, particularly in small studies.
Detection of the differentially expressed gene IGF-binding protein-related protein-1 and analysis of its relationship to fasting glucose in Chinese colorectal cancer patients.
Authors: Shao L , Huang Q , Luo M , Lai M
Published: December 2004

IGF-binding protein-related protein-1 (IGFBP-rP1) is a member of the IGF axis. In our previous work, we separated cDNA fragments of IGFBP-rP1 from colonic adenocarcinoma and normal mucosa cDNA subtraction libraries. In this study, we compared the expression of IGFBP-rP1 by semi-quantitative RT-PCR and immunohistochemistry among colorectal cancer, adenoma, normal tissue adjacent to cancer site, and normal tissue. Associations between IGFBP-rP1 and plasma glucose were further explored. We found that the mRNA level of IGFBP-rP1 was highest in cancer, moderate in adenoma and tissue adjacent to the cancer site and lowest in normal tissue (P<0.05). A significant difference was found in the immunoreactivity of IGFBP-rP1 between paired normal and cancer tissue (P<0.05). Tumor samples with upregulated expression of IGFBP-rP1 in invading tumor cells showed an increased frequency of metastasis to the lymph node, an increased depth of infiltration and stronger staining of IGFBP-rP1 compared with other samples (P<0.05). The fasting glucose level was significantly correlated with the staining of IGFBP-rP1 in cancer tissue (Spearman's rho=0.4, P<0.000). Thus, we concluded overexpression of IGFBP-rP1 might play an important role in the initiation and promotion of colorectal cancer. IGFBP-rP1 expression may also be associated with fasting glucose level and the presence of diabetes mellitus.
Spontaneous enterochromaffin-like cell carcinomas in cotton rats (Sigmodon hispidus) are prevented by a somatostatin analogue.
Authors: Fossmark R , Martinsen T C , Torp S H , Kawase S , Sandvik A K , Waldum H L
Published: December 2004

Among inbred female cotton rats (Sigmodon hispidus) 25-50% of the animals develop spontaneous gastric carcinomas; the corresponding figure for male cotton rats is approximately 1%. Animals with carcinomas have hypergastrinaemia and gastric hypo-anacidity and the tumours are derived from enterochromaffin-like (ECL) cells. The mechanism behind the hypo-anacidity is unknown. Carcinomas are found in all female cotton rats with hypergastrinaemia lasting more than 4 months and this represents an excellent animal model for studying gastric carcinogenesis. In this study, the somatostatin analogue octreotide was given to female cotton rats to prevent carcinoma development caused by hypergastrinaemia. Twelve female cotton rats were given monthly injections of long-acting octreotide (5 mg i.m.) for 6 months. A control group of 20 animals was not given injections. Of the 20 control animals, 13 developed hypergastrinaemia and histologically invasive carcinomas or dysplasia. Of the 12 animals in the octreotide group, five developed hypergastrinaemia. None of these five animals developed histological cancer (P<0.05), whereas three had dysplasia. However, octreotide did not affect plasma gastrin concentration or antral gastrin mRNA abundance significantly. Dysplasia of the oxyntic mucosa in hypergastrinaemic animals was accompanied by a marked increase in chromogranin A-immunoreactive cells and cells positive for Sevier-Munger staining. The malignant tissue also contained groups of cells with Sevier-Munger staining. In conclusion, octreotide prevented ECL cell carcinomas in hypergastrinaemic cotton rats without lowering the gastrin concentration.
Aromatase inhibitors in breast cancer.
Authors: L√∏nning P E
Published: December 2004

The development of aromatase inhibitors for breast cancer therapy is a result of successful translational research exploring the biochemical effects of different compounds in vivo. Studies assessing plasma oestrogen levels as well as in vivo aromatase inhibition have revealed a consistent difference with respect to biochemical efficacy between the third generation compounds (anastrozole, letrozole and exemestane) and the previous, first and second generation drugs, corresponding to the improved clinical effects of these compounds as outlined in large phase III studies. Thus, endocrine evaluation has been found to be a valid surrogate parameter for clinical efficacy. Moreover, the results from these studies have added important biological information to our understanding of endocrine regulation of breast cancer. Based on the clinical results so far, aromatase inhibitors are believed to play a key role in future adjuvant therapy of postmenopausal breast cancer patients and potentially also for breast cancer prevention. Interesting findings such as the lack of cross-resistance between steroidal and non-steroidal compounds should be further explored, as this may add additional information to our understanding of breast cancer biology.
Copper deficiency as an anti-cancer strategy.
Authors: Goodman V L , Brewer G J , Merajver S D
Published: December 2004

Copper is a tightly regulated trace element. Disruptions of copper homeostasis are rare and they cause serious disorders such as Wilson's disease and Menkes disease. Copper also plays an important role in promoting physiological and malignant angiogenesis. Formation of new blood vessels by a tumor enables tumor growth, invasion and metastasis. The copper chelator tetrathiomolybdate (TM), which quickly and effectively depletes copper stores, is under investigation as an anti-angiogenic agent. Promising results in vitro, in pre-clinical animal models and in an early (phase I) clinical trial have led to ongoing phase II evaluation of TM in patients with advanced cancers.
Molecular mechanisms of androgen receptor-mediated gene regulation: structure-function analysis of the AF-1 domain.
Authors: McEwan I J
Published: December 2004

The androgen receptor is a ligand-activated transcription factor that binds DNA response elements as a homodimer. Binding sites for the receptor have been identified both upstream and downstream of the transcription start site. Once bound to DNA, the receptor contacts chromatin remodelling complexes, coactivator proteins and components of the general transcription machinery in order to regulate target gene expression. The main transactivation domain, termed AF1, is located within the structurally distinct amino-terminal domain. This region is structurally flexible but adopts a more folded conformation in the presence of the binding partner TFIIF, and this in turn enhances subsequent protein-protein interactions. Thus, there is likely to be a dynamic interplay between protein-protein interactions and protein folding, involving AF1, that is proposed to lead to the assembly and/or disassembly of receptor-dependent transcription complexes.
Gene expression profiling in human insulinoma tissue: genes involved in the insulin secretion pathway and cloning of novel full-length cDNAs.
Authors: Wang X-C , Xu S-Y , Wu X-Y , Song H-D , Mao Y-F , Fan H-Y , Yu F , Mou B , Gu Y-Y , Xu L-Q , Zhou X-O , Chen Z , Chen J-L , Hu R-M
Published: December 2004

Insulinoma is a clinically common cause of organic hypoglycemia. The prominent characteristic of insulinoma is endogenous hyperinsulinism. Until now, the molecular biology of human insulinoma has been little understood. In this study, gene expression profiling of human insulinoma was established by expressed sequence tag (EST) sequencing and cDNA array. A total of 2063 clones were obtained, of these, 1589 clones were derived from EST sequencing, 975 clones were derived from cDNA array and 501 clones were shared by the two methods. G protein alpha-stimulating activity polypeptide (Gsalpha) and carboxypeptidase E (CPE) were the most highly expressed genes in human insulinoma, as derived by EST sequencing and cDNA array respectively. The genes involved in the protein/insulin secretion pathway were strongly expressed in human insulinoma tissue. Meanwhile, eight full-length cDNAs of novel genes were cloned and sequenced. The results demonstrated the molecular biology of human insulinoma tissue at the level of transcript abundance and validated the efficacy of EST sequencing combined with cDNA array in the construction of gene expression profiling. In conclusion, the predominance of the genes participating in the secretory pathway suggested that regulation of secretion might be a major mechanism by which insulin release is abnormally increased in patients with insulinomas. It was also concluded that overexpression of the Gsalpha gene played an important role in the pathogenesis of insulinoma.
FSH and LH serum/tumor fluid ratios and malignant tumors of the ovary.
Authors: Rzepka-G√≥rska I , Chudecka-G≈Çaz A , Kosmowska B
Published: December 2004

The aim of this work was to compare mean concentrations of gonadotropins in serum and fluid from malignant and benign ovarian tumors. We enrolled 126 patients diagnosed with malignant epithelial tumors (n=40), borderline epithelial tumors (n=14), benign cystadenomas (n=28) and simple cysts (n=44) of the ovary. Premenopausal and postmenopausal subgroups were formed in each group. The concentration of FSH and LH was measured in serum and tumor fluid and the serum/tumor fluid ratio was calculated. The results in each group were compared and the sensitivity, specificity, positive and negative predictive values were determined. Mean concentrations of both gonadotropins in ovarian cancer fluid were significantly higher than in the remaining groups (P ranged from <0.005 to <0.0001). Mean serum/fluid ratios were lowest in ovarian cancer (FSH=2.91, LH=4.19). Our findings support the hypothesis that gonadotropins are involved in ovarian carcinogenesis and suggest that gonadotropin serum/tumor fluid ratios could be of value in the differential diagnosis of functional and organic cysts of the ovary.
Postoperative calcitonin study in medullary thyroid carcinoma.
Authors: Ismailov S I , Piulatova N R
Published: December 2004

Calcitonin (CT) is a sensitive marker for medullary thyroid carcinoma. Normalization of early postoperative CT level is a favorable prognostic factor. The aim of this study was to establish the prognostic value of CT-level kinetics by preoperative tumor stage and postoperative elimination rate. Blood serum from 22 medullary thyroid carcinoma (MTC) patients without remote metastases was assayed. A commercial RIA DSL-1200 test was used to assay CT levels. Basal CT< or =42 pg/ml and stimulated CT< or =120 pg/ml were considered normal. The patients were divided into three groups according to the intensity of the postoperative CT level reduction in blood serum. Group 1 comprised patients who showed basal CT normalization within the first 2-3 days after surgery. Group 2 included those patients with slow (from 2 to 4 weeks) CT-level normalization. Group 3 included patients with CT levels that reduced within 14 days, but subsequently increased. Preoperative basal CT varies from 216 to 1654 pg/ml and depends on tumor-node-metastasis (TNM) stage. In seven patients, no basal CT decrease to normal values was observed; in five of these patients, disease recurrence was detected 2-6 months after surgery. In the group with slowly decreasing CT levels, no strong correlation between preoperative CT level and the postoperative time to normalization of basal and peak CT could be established; this may be due to the small number of patients. Our study showed that preoperative CT level depended on the disease stage. Postoperative CT elimination rate is independent of preoperative CT level. Postoperative increase in the basal or stimulated CT level is an unfavorable prognostic factor, implying disease recurrence.
Relationship of AgNOR counts and nuclear DNA content to survival in patients with parathyroid carcinoma
Authors: Lumachi F , Ermani M , Marino F , Poletti A , Basso SMM , Iacobone M , Favia G
Published: December 2004

The aim of this study was to evaluate the usefulness of DNA flow cytometry to determine tumor nuclear DNA index (DI), and nucleolar organizer region protein counts visualized by the argyrophil (AgNOR) technique, in confirming diagnosis and predicting clinical outcome of patients with parathyroid carcinoma (PC). We reviewed paraffin-embedded tissue sections, from 15 patients (median age 63 years, range 30–68 years) with PC who died of the disease, which were randomly compared with tissue sections from 15 age- and sex-matched patients with parathyroid adenoma (PA). The proliferative activity in parathyroid tumours as detected by DI and AgNOR counts was evaluated in all specimens. Both DI (1.37 ± 0.33 vs 1.0 ± 0.1) and AgNOR (3.01 ± 0.31 vs 1.54 ± 0.35) counts were higher (P < 0.001) (Student’s t-test) in patients with PC than in those with PA. Diploid (DI = 1), aneuploid (DI>1) and hypoploid (DI<1) neoplasms were found in 11 (PC = 4, PA = 7), 14 (PC = 11, PA = 3) and five (PC = 0, PA = 5) patients respectively. The average postoperative survival in patients with PC was 46.9 ± 37.4 months (range 21–146 months). The survivals of patients with aneuploid (n = 11) and diploid (n = 4) PC were 74.0 ± 58.1 and 34.1 ± 18.4 months (P=0.21) respectively. There was a significant relationship between DI and AgNOR counts (R=0.69, P < 0.01), but no correlation was found between survival and both DI (Rho = 0.17, P = 0.55) and AgNOR counts (Rho = 0.26, P = 0.35). Moreover, there was no correlation (P = NS) between the main preoperative biochemical parameters and survival. In conclusion, DI and AgNOR are useful in confirming the diagnosis of PC, but they are of little value in predicting the clinical outcome of patients with PC.
Loss of ERβ expression as a common step in estrogen-dependent tumor progression
Authors: Bardin A , Boulle N , Lazennec G , Vignon F , Pujol P
Published: December 2004

The characterization of estrogen receptor beta (ERβ) brought new insight into the mechanisms underlying estrogen signaling. Estrogen induction of cell proliferation is a crucial step in carcinogenesis of gynecologic target tissues, and the mitogenic effects of estrogen in these tissues (such as breast, endometrium and ovary) are well documented both in vitro and in vivo. There is also an emerging body of evidence that colon and prostate cancer growth is influenced by estrogens. In all of these tissues, most studies have shown decreased ERβ expression in cancer as compared with benign tumors or normal tissues, whereas ERα expression persists. The loss of ERβ expression in cancer cells could reflect tumor cell dedifferentiation but may also represent a critical stage in estrogen-dependent tumor progression. Modulation of the expression of ERα target genes by ERβ or ERβ-specific gene induction could explain that ERβ has a differential effect on proliferation as compared with ERα. ERβ may exert a protective effect and thus constitute a new target for hormone therapy, such as ligand specific activation. The potential distinct roles of ERα and ERβ expression in carcinogenesis, as suggested by experimental and clinical data, are discussed in this review.
Dexamethasone modulates insulin receptor expression and subcellular distribution of the glucose transporter GLUT 1 in UMR 106-01, a clonal osteogenic sarcoma cell line
Authors: Thomas D M , Rogers S D , Ng K W , Best J D
Published: December 2004

Corticosteroids have profound effects on bone metabolism, though the underlying mechanisms remain unclear. They are also known to alter glucose metabolism, in part by induction of insulin resistance. To determine whether corticosteroids impair glucose metabolism in bone cells, we have examined the actions of dexamethasone (DEX) on glucose transport and insulin receptor expression using osteoblast-like UMR 106-01 cells. DEX was shown to inhibit basal 2-deoxyglucose uptake by up to 30% in a time- and dose-dependent manner. It inhibited insulin-stimulated glucose transport by 13%. By Northern and Western blot analysis, DEX was shown to stimulate insulin receptor mRNA and protein by up to 5·6-fold, but it had no effect on expression of the glucose transporter GLUT 1 mRNA or protein under basal conditions. However, DEX augmented insulin-stimulated GLUT 1 mRNA and protein levels. By Scatchard analysis of labelled insulin binding, DEX increased insulin receptor number per cell by 54%. Subcellular fractionation and Western blot analysis demonstrated that DEX caused a redistribution of immunoreactive GLUT 1 from plasma membrane to intracellular microsomes, resulting in a 21% decrease in GLUT 1 at the plasma membrane. These data suggest that (i) DEX impairs basal glucose transport by post-translational mechanisms in UMR 106-01 cells, (ii) DEX increases insulin receptor mRNA, protein and insulin binding and (iii) the inhibition of glucose transport by DEX dominates its effects on the insulin receptor. It is possible that DEX inhibition of glucose transport in osteoblasts may contribute to steroid-induced osteoporosis.
Expression of activin βC subunit mRNA in reproductive tissues
Authors: Loveland K L , McFarlane J R , de Kretser D M
Published: December 2004

A cDNA encoding the potential activin βC subunit was produced from human testis RNA using reverse transcription and PCR and then used as a probe in Northern blot analysis of poly(A)+ RNA. A transcript of ∼1·8 kb was evident in human ovary, placenta and testis samples. A transcript of this size was also detected in adult rat caput and cauda epididymis, and adult and day-15 testis and adult spleen, while adult liver contained a single transcript of ∼2·1 kb. Poly(A)+ RNA from primary spermatocytes but not from round spermatids contained the 1·8kb activin βC mRNA. These findings highlight the need for further studies to determine the physiological role(s) of activin βC in a wide variety of tissues.
Production of [3H]choline-labelled metabolites from endogenously 3H-labelled phosphatidylcholine in mouse pancreatic islets
Authors: Capito K , Hansen S E , Thams P
Published: December 2004

The involvement of phosphatidylcholine (PC) hydrolysis in the regulation of insulin secretion was studied in mouse pancreatic islets prelabelled with [3H]choline. Phospholipase C (PLC) and phospholipase D (PLD) activities were demonstrated and also that of an enzyme that removes both fatty acids from PC and thus catalyses the production of [3H]glycerophosphorylcholine (GroPCho). After 2 min of incubation with 20 mm glucose a 35% increase in the content of [3H]GroPCho was observed in prelabelled islets, whereas the amount of [3H]lysoPC, [3H]phosphorylcholine (PCho) and [3H]choline was unaffected. After 30 min of incubation with 20 mm glucose, 0·2 mm tolbutamide, 40 mm KC1, 10 mm succinic acid monomethyl ester (SME) or 10 mm NaF, a 25-50% increase in [3H]GroPCho was observed. In the presence of 100 μm diazoxide or 35 μm RHC 80267 the glucose activation was attenuated. PLC was stimulated slightly by tolbutamide and 100 μm isoprenaline (isoproterenol), whereas SME decreased the amount of [3H]PCho by 10%. [3H]Choline content was increased by 25-40% in the presence of 0·16 μm 12-O-tetradecanoylphorbol 13-acetate (TPA), 10 mm NaF or 100 μm carbachol. This effect of fluoride was potentiated in the presence of 20 mm glucose. It is concluded that metabolism of PC to GroPCho may be involved in the regulation of glucose-stimulated insulin secretion, and that PLD may participate in insulin secretion evoked by TPA, carbachol and fluoride.
The role of fetal parathyroid hormone-related protein in transplacental calcium transport
Authors: Tucci J , Hammond V , Senior P V , Gibson A , Beck F
Published: December 2004

During pregnancy, a placental calcium pump maintains the fetus in a hypercalcaemic state relative to the mother, a condition which has been thought to facilitate normal development of the fetal skeleton. Based on experiments performed in the sheep, parathyroid hormone-related protein (PTHrP) has been implicated as the hormone responsible for maintaining the placental calcium pump. In the present study on mice in which the PTHrP gene has been ablated by homologous recombination, we have measured both fetal and maternal circulating total and ionised calcium levels, as well as fetal total body calcium, in order to determine whether absence of PTHrP during fetal development has an effect on fetal calcium levels. Our results show that, in fetuses lacking PTHrP, circulating ionised calcium levels are significantly lower than those of heterozygote and wild-type littermates, but circulating total calcium levels show no difference. Total body calcium levels of null mutants are significantly higher than those of normal littermates.

The role of PTHrP in maintaining the integrity of the transplacental calcium pump in the rodent thus remains unclear. It may be that the lower levels of fetal blood ionised calcium in mutant animals are due to disruption of the placental pump, but, if this is the case, compensatory mechanisms have operated to allow the excessive calcium deposition seen in the skeletons of these animals. Alternatively, the increased avidity of the bones for calcium may in itself have produced a lower equilibrium level of available ionised calcium.
Effect of lymphocytes on hormonal secretion by autologous thyrocytes cultured in monolayers
Authors: Massart C , Gibassier J , Genetet N , Raoul M L , Baron M , Le Gall F , Lucas C
Published: December 2004

We studied the lymphocyte-induced alterations in hormonal metabolism and the production of tumour necrosis factor α (TNF-α) during coculture of thyrocytes and autologous lymphocytes from 20 patients with Graves' disease and from five normal subjects. Thyroglobulin (Tg) mRNA was assessed by slot-blot analysis under TSH stimulation. Tg, tri-iodothyronine (T3) and cAMP secretion in the presence of TSH were measured by RIA after 3 or 5 days of coculture. TNF-α levels produced after 5 days incubation were also assayed in lymphocyte culture and coculture media.

Lymphocytes isolated from peripheral blood (PBLs) altered the production of Tg, T3 and cAMP in autologous thyrocytes. Intrathyroidal lymphocytes (ITLs) decreased Tg and cAMP secretion but had no effect on T3 secretion. The reductions in Tg and cAMP levels obtained with mechanically isolated ITLs (M-ITLs) were generally higher than those obtained with ITLs isolated by dispase (D-ITLs). No difference was seen between Graves' disease and normal cocultures. PBLs secreted large concentrations of TNF-α, larger than those obtained with M-ITLs whereas D-ITLs produced low amounts of this cytokine. In coculture, TNF-α levels were lower than those observed in lymphocyte culture. Significant correlations were obtained between TNF-α levels and the decrease in Tg, T3 and cAMP concentrations. The percentage of T lymphocytes was higher in PBLs and D-ITLs than in M-ITLs. B lymphocytes levels were higher in ITLs, especially M-ITLs, than in PBLs. TNF-α production by B lymphocytes was maximal in M-ITLs.

In conclusion, lymphocytes induced a decrease in hormonal thyroid metabolism when cocultured with autologous thyrocytes. These perturbations may be attributed, at least partly, to TNF-α secreted by lymphocytes. TNF-α interacts via the adenylate cyclase pathway of TSH signal transduction.
Insulin-like growth factor (IGF)-I A- and B-domain analogues with altered type 1 IGF and insulin receptor binding specificities
Authors: Shooter G K , Magee B , Soos M A , Francis G L , Siddle K , Wallace J C
Published: December 2004

Insulin-like growth factor-I (IGF-I) analogues were produced with the aim of identifying IGF-I residues that contribute to the specificity of binding to the type 1 IGF receptor as opposed to the insulin receptor. Receptor binding properties of a series of A- and B-domain analogues were compared using rat L6 myoblasts, soluble human IGF type 1 receptors and soluble human insulin receptor isoforms HIR-A (−Ex11) and HIR-B (+Ex11). IGF-I analogues, [Leu8] IGF-I and [Phe59] IGF-I, were shown to exhibit respectively, a 28- and 17-fold decrease in affinity for the HIR-A with only a 6- and 5-fold decrease in affinity for the human IGF type 1 receptor. In contrast, the analogue [His4] IGF-I was equipotent to IGF-I in binding to the soluble type 1 IGF receptor while showing 7-fold and 4-fold increases in HIR-A and HIR-B binding respectively. Furthermore, [Leu62] IGF-I was 8-fold less potent than IGF-I in soluble IGF type 1 receptor binding but only showed a 2-fold decrease in HIR-A and HIR-B binding. Our study supports the conclusion that the co-evolution of the IGF-I and insulin receptor/ligand systems has resulted in subtle structural differences in the A- and B-regions of each ligand important for defining receptor binding specificity.
Ontogeny of FSH receptor messenger ribonucleic acid transcripts in relation to FSH secretion and testicular function in sheep
Authors: Yarney T A , Fahmy M H , Sairam M R , Khan H , Macdonald E A
Published: December 2004

The role of alternative splicing of the FSH receptor gene in the generation of FSH receptor proteins and testicular function remains an enigma. To address this issue, this investigation was conducted to determine variations in the expression of alternate FSH receptor mRNA transcripts in relation to changes in FSH release, hormone binding activity and testicular function during pubertal development of ram lambs from two genotypes of sheep (Romanov and a cross between Booroola × DLS) with different sexual precocity. Serum 17β-estradiol and testosterone concentrations were used as indices of Sertoli cell and testicular function. The results indicated that increases in Sertoli cell and testicular function normally seen during pubertal development are accompanied by age-dependent reductions in concentration of functional FSH receptors, as determined by binding of iodinated FSH to testicular membrane preparations. During the course of these changes, FSH release was either maintained at a steady level in Romanov lambs or it was gradually reduced in the Booroola × DLS cross, thus indicating that the testis had become more responsive to hormonal signal. This acquisition of heightened sensitivity was also associated with contrasting changes in the level of expression of FSH receptor mRNA transcripts. For both genotypes of sheep, 5 distinct species of mRNA transcripts of approximately 1·1, 1·5, 2·0, 2·5 and 6·5 kb were highly expressed from 11 to 22 weeks of age. Amongst these transcripts, the 1·1 kb molecular species was the most abundant. Specific probing for a previously cloned transcript called 151A1 representing the first 4 exons of the FSH receptor gene revealed a paradoxical increase in the level of expression from 11 weeks up to a maximum at 18-22 weeks of age for both genotypes. Collectively, the results indicated that contrasting changes in the production of specific alternatively spliced mRNA transcripts may mediate changes in FSH receptor expression which apparently accounts for the augmentation in sensitivity and function of the testis during pubertal development. Furthermore, the data provide the first important indication that the novel truncated transcript (151A1), which predictably encodes a soluble protein of either intra- or extracellular fate, could be physiologically relevant.
Cloning of the human orphan receptor germ cell nuclear factor/retinoid receptor-related testis-associated receptor and its differential regulation during embryonal carcinoma cell differentiation
Authors: Lei W , Hirose T , Zhang L-X , Adachi H , Spinella M J , Dmitrovsky E , Jetten A M
Published: December 2004

We have cloned a cDNA encoding the full-length coding region of the human homologue of the germ cell nuclear factor (GCNF)/retinoid receptor-related testis-associated receptor (RTR), from a human testis cDNA library. The amino acid sequence of human GCNF/RTR is highly homologous to that of the mouse GCNF/RTR. The largest difference between the two homologues is a 15 amino acid deletion in the human GCNF/RTR at amino acid 47. The GCNF/RTR gene was localized on human chromosome 9. Northern blot analysis using poly(A)+ RNA from different human tissues showed that GCNF/RTR mRNA is most abundantly expressed in the testis. GCNF/RTR was also highly expressed in embryonic stem cells and embryonal carcinoma cells but repressed in its differentiated derivatives. Induction of differentiation of mouse embryonal carcinoma F9 cells and human embryonal carcinoma NTERA-2 clone Dl (NT2/D1) cells by all-trans retinoic acid was accompanied by a down-regulation of GCNF/RTR. Our observations suggest that GCNF/RTR plays a role in the control of gene expression in early embryogenesis and during spermatogenesis.
Downregulation of IGF-I mRNA expression during postnatal pancreatic development and overexpression after subtotal pancreatectomy and acute pancreatitis in the rat pancreas
Authors: Calvo E L , Bernatchez G , Pelletier G , Iovanna J L , Morisset J
Published: December 2004

Insulin-like growth factors (IGFs) are important peptides involved in the regulation of cell growth and differentiation in many tissues. The ontogeny of IGF-I was examined in pancreata from 19-day rat fetuses, newborns and 5-, 11-, 26- and 70-day-old rats. For the regeneration studies two models were used: (i) 90% pancreatectomy was carried out and the rats were killed at 1, 2, 3 and 6 days after resection; (ii) acute pancreatitis was induced with caerulein (12μg/body weight three times a day every 8 h for 2 days) and the rats were killed at 1, 2, 5, 7 and 9 days after the first injection. Total RNA was extracted by the guanidinium isothiocyanate method and Northern blots were performed using total RNA and labeled cRNA probes. Abundance of the different mRNA transcripts was estimated by densitometric scanning and normalized to the abundance of 18 S rRNA for each time point. Northern blot analysis during ontogeny showed four (0·8–1·2, 1·9, 4·7 and 7·5 kb) major transcripts in the rat pancreas and liver. Total IGF-I mRNA was 40-fold higher in the adult liver than in the adult pancreas. Moreover, in the liver, IGF-I mRNA levels were higher in the adult than in the fetus, whereas in the pancreas, the highest levels were observed around birth. During the first 3 days after pancreatectomy, a peak of maximal expression was observed after the second day. Densitometric analysis of each IGF-I mRNA species showed concomitant increases in all transcripts. After 6 days, all transcripts had returned to near-control values. IGF-I mRNA expression 2 days after pancreatectomy was 3·5-fold higher than in the newborn. During the first 2 days of acute pancreatitis induction, overexpression of IGF-I mRNA was observed. However, soon after the second day of caerulein treatment, the 7·5 kb transcripts remained elevated whereas those of the others regressed toward control values. Our results show that IGF-I mRNA is overexpressed in both models of pancreatic regeneration but downregulated in the normal adult pancreas.
Homodimer formation by the individual subunits of bovine lutropin as determined by sedimentation equilibrium
Authors: Peng K-C , Puett D , Brewer J M
Published: December 2004

Although differing in their amino acid sequences, the folding patterns of the α and β subunits of human choriogonadotropin are similar in the crystal structure of the HF-treated glycoprotein hormone. Each subunit forms a cystine-knot motif like that found in several growth factors that form homodimers and heterodimers. In order to ascertain if the α and β subunits can self-associate, e.g. to form homodimers, sedimentation equilibrium at various glycoprotein concentrations and temperatures was used to study the subunits of bovine lutropin, which are expected to exhibit conformations like those of the choriogonadotropin subunits. Each subunit was found to form homodimers with Kd values of 0·3 and 0·1 mm for α and β respectively at 37 °C. Self-association was weakly exothermic for α and endothermic for β; entropic factors made a major contribution for each. It is unlikely that homodimer formation of either subunit would be physiologically important, although homodimers may form to some extent intracellularly because of the relatively high concentrations during biosynthesis.
The interaction of CGRP and adrenomedullin with a receptor expressed in the rat pulmonary vascular endothelium
Authors: Han Z-Q , Coppock H A , Smith D M , Van Noorden S , Makgoba M W , Nicholl C G , Legon S
Published: December 2004

An abundant, seven trans-membrane domain receptor related to the calcitonin receptor has been studied by a number of groups without identification of its ligand. A recent report claimed that the receptor was a type 1 CGRP receptor (Aiyar et al J. Biol. Chem. 271 11325-11329 (1996)). We have studied the equivalent rat sequence in transfected cells. When expressed in 293 cells the receptor interacts with CGRP and adrenomedullin with KD values of 1.2 nM for CGRP and 11 nM for adrenomedullin. Both ligands cause an elevation of intracellular cAMP with EC50 values of 4 nM and 20 nM respectively and these effects are inhibited by the antagonist CGRP8-37. The receptor is expressed at high levels in the pulmonary vascular endothelium. Both the pharmacological data and the localisation are consistent with the conclusion that the orphan receptor is a type 1 CGRP receptor. However, when expressed in COS-7 cells, no receptor activity could be demonstrated suggesting that 293 cells contain a factor necessary for functional receptor expression.
Nutritional regulation of insulin-like growth factor-I mRNA expression in barramundi, Lates calcarifer
Authors: Matthews S J , Kinhult A K K , Hoeben P , Sara V R , Anderson T A
Published: December 2004

The effect of nutritional status on IGF-I mRNA expression in the liver and brain of juvenile barramundi (Lates calcarifer) was investigated. Fish were either fed a satiety ration (SAT) or starved (STV) for 6 weeks. Starved fish demonstrated significantly lower condition factor and hepatic IGF-I mRNA expression at 3 and 6 weeks, when compared with the SAT group. IGF-I mRNA expression in the brain was 10 fold lower than the liver and was not affected by ration size. These results suggest the liver is the major site of IGF-I mRNA synthesis and hepatic but not brain IGF-I mRNA expression is regulated by food availability in juvenile barramundi.
Cloning of cDNA for goldfish activin βB subunit, and the expression of its mRNA in gonadal and non-gonadal tissues
Authors: Ge W , Miura T , Kobayashi H , Peter R E , Nagahama Y
Published: December 2004

We have cloned a full length cDNA coding for activin βB subunit from the goldfish ovary. Sequence analysis of the goldfish activin βB shows that this peptide is extremely conserved across vertebrates. The mature region of goldfish activin βB has 93 and 98% amino acid identity with that of human and zebrafish βB subunit respectively. The identity of the cloned goldfish activin βB was further confirmed by expressing the protein in the Chinese hamster ovary (CHO) cells followed by detection of the specific activity of activin in the culture medium using F5-5 cell assay. mRNA of goldfish activin βB is expressed in a variety of goldfish tissues including ovary, testis, brain, pituitary, kidney and liver, suggesting a wide range of physiological roles for activin in the goldfish.
IGF, type I IGF receptor and IGF-binding protein mRNA expression in kidney and liver of potassium-depleted and normal rats infused with IGF-I
Authors: van Neck J W , Flyvbjerg A , Schuller A G P , Rosato R R , Groffen C , van Kleffens M , Lindenbergh-Kortleve D , Dørup I , Drop S L S
Published: December 2004

Dietary potassium (K) depletion is known to reduce body weight gain and organ growth, except for kidney which increases in weight. This renal hypertrophy is preceded by increased renal IGF-I levels. In the present study, we investigated IGF-I and -II, type I IGF receptor and IGF-binding protein (IGFBP) mRNA expression in liver and kidney of K-depleted and normal rats infused with vehicle or recombinant human IGF-I. Body weight gain was almost completely arrested in K-depleted rats without any stimulatory effect of IGF-I infusion. Both absolute and relative kidney weight (kidney weight/body weight) were significantly increased in K-depleted rats and this was further enhanced by IGF-I infusion. In contrast, relative liver weight was comparable in the different groups and unaffected by IGF-I infusion.

IGF-I mRNA expression was significantly lower in kidney and liver of K-depleted animals whereas type I IGF receptor levels were unchanged. In contrast, in kidney, K depletion increased IGFBP-1 and -2 mRNA expression with no additional effect of IGF-I infusion. In liver of K-depleted animals, IGFBP-1 mRNA expression was increased whereas increased IGFBP-1 and -2 mRNA expression was observed when these animals were infused with IGF-I. These observations may point towards a differential mode of action of the IGFBPs. In kidney increased IGFBP-1 and -2 mRNA expression may enhance IGF-I bioavailability with subsequent kidney growth. In liver, with clearly detectable type I IGF receptor mRNA expression, increased IGFBP levels may protect from IGF-I-induced organ growth by decreasing IGF-I bioavailability.
Cloning of mouse islet amyloid polypeptide gene and characterization of its promoter
Authors: Ekawa K , Nishi M , Ohagi S , Sanke T , Nanjo K
Published: December 2004

Islet amyloid polypeptide (IAPP) was isolated from islet amyloid deposits in patients with insulinoma and pancreatic islets of non-insulin-dependent diabetes mellitus (NIDDM) and several reports suggested that it may contribute to the development of NIDDM. IAPP is mainly expressed and synthesized in pancreatic B cells and cosecreted with insulin, so analysis of the transcriptional regulation of the IAPP gene would be helpful for the elucidation of pancreatic B cell specific gene expression. The mouse IAPP gene spans about 5·8 kb and, like the human and rat genes, it consists of three exons, and analysis of the promoter/enhancer activity of mouse IAPP gene reveals the region from − 171 to − 87 bp to be essential. Within this region, an E-box like sequence, CACCTG (− 122 to − 117 bp), and a TAAT-box like sequence, TTAATG (− 139 to − 134 bp), are thought to be important. The disruption of each sequence resulted in a severe decrease in promoter activity, although the decrease was less in the disruption of the E-box than that of TAAT-box like sequence, suggesting the latter is more important for IAPP gene transcription. Like the rat IAPP gene, the CCAAT-box, which does not exist in the human gene, was identified in the mouse gene, indicating the possibility of species difference in the IAPP gene transcriptional mechanism. An enhancer-like activity was also identified within intron 1, although further elucidation is necessary.