bluuebunny/crossref_metadata_2025 huggingface dataset:
What is acceptable for women may not be for men: The effect of family conflicts with work on job‐performance ratings
Authors: Butler Adam B. , Skattebo Amie
Published: December 2004

We conducted a laboratory study examining the effect of a family conflict with work on performance appraisal ratings given to men and women. Overall, the experience of a family conflict was associated with lower performance ratings, and ratee sex moderated this relationship. Men who experienced a family conflict received lower overall performance ratings and lower reward recommendations than men who did not, whereas ratings of women were unaffected by the experience of a family conflict. The sex bias was not evident when performance was evaluated on the more specific dimension of planning. Neither rater gender nor work‐family role attitudes moderated the sex bias. Implications for future research and practice are discussed.
Psychometric problems and issues involved with creating and using ipsative measures for selection
Authors: Meade Adam W.
Published: December 2004

Data are described as ipsative if a given set of responses always sum to the same total. However, there are many properties of data collection that can give rise to different types of ipsative data. In this study, the most common type of ipsative data used in employee selection (forced‐choice ipsative data; FCID) is discussed as a special case of other types of ipsative data. Although all ipsative data contains constraints on covariance matrices (covariance‐level interdependence), FCID contains additional item‐level interdependencies as well. The psychological processes that give rise to FCID and the resultant psychometric properties are discussed. In addition, data from which both normative and ipsative responses were provided by job applicants illustrate very different patterns of correlations as well as very different selection decisions between normative, FCID and ipsatized measures.
Influence of a Long-Term Retarder on the Hydration of Clinker and Cement
Authors: Rickert J , Thielen G
Published: December 2004

This paper summarizes the results of investigations on the effects of a long-term retarder (LTR) based on phosphonic acid (PBTC) on the hydration of several clinker phases (C3S, C3A, C4AF), Portland cement clinker, and Portland cement. It could be shown that long-term retardation is due to a thin sparingly soluble layer of calcium phosphonate on the particle surface. The formation of sparingly soluble calcium phosphonate requires 2.5 moles Ca2+ per mole PBTC. If enough Ca2+ is available, sparingly soluble calcium phosphonate precipitates and forms a layer around the cement particles, which retards further hydration immediately. In the contrary a lack of Ca2+ causes a short-term acceleration in hydration of the reactive clinker phase C3A. The investigations show that a controlled long-term retardation can only be achieved if the cement shows an optimal “natural” setting retardation; hence, when the sulphate ingredient is fully compatible with the reactivity of C3A.
Control of Cracking in Bridge Decks: Observations from the Field
Authors: Darwin D , Browning J , Lindquist WD
Published: December 2004

Crack surveys of bridge decks, performed over a 10-year period in northeast Kansas as part of three studies, provide strong guidance in identifying the parameters that control cracking in these structures. The surveys involve steel girder bridges—bridges that are generally agreed to exhibit the greatest amount of cracking in the concrete decks. The surveys include monolithic decks and decks with silica fume and conventional concrete overlays. The study demonstrates that crack density increases as a function of cement and water content, and concrete strength. In addition, crack density is higher in the end spans of decks that are integral with the abutments than decks with pin-ended supports. Most cracking occurs early in the life of a bridge deck, but continues to increase over time. This is true for bridges cast in both the 1980s and the 1990s. A key observation, however, is that bridge decks cast in the 1980s exhibit less cracking than those in the 1990s, even with the increase in crack density over time. Changes in materials, primarily cement fineness, and construction procedures over the past 20 years, are discussed in light of these observations. A major bright spot has been the positive effect of efforts to limit early evaporation, suggesting that the early initiation of curing procedures will help reduce cracking in bridge decks.
A Phenomenological Approach to Obtaining Correlations between Accelerated and Outdoor Exposure Test Results for Organic Materials
Authors: Jorgensen GJ
Published: December 2004

Two approaches are commonly used to derive correlations between in-service and accelerated exposure test results. When detailed degradation mechanisms are well understood, a deterministic formalism can be applied in which a precise damage function model is utilized. If failure mechanisms are not known or multiple mechanisms interact in a complicated manner that makes it difficult and tedious to treat them explicitly, a probabilistic procedure can be used. Observed failures are fit to appropriate life distributions to obtain expressions for related failure rates. A third approach uses a phenomenological methodology. This procedure is similar to the deterministic approach in that damage functions are hypothesized, except that they are based on macroscopic observations and effects, rather than on microscopic mechanisms. The phenomenological approach is used herein to describe results accurately from a number of highly accelerated exposure tests of organic materials. The ensuing damage function models are then used to predict real-world behavior. Excellent agreement is demonstrated between these predictions and actual measured data, thereby validating the phenomenological approach and providing a very useful way to estimate service life of organic-based materials.
The Mental Retardation Protein PAK3 Contributes to Synapse Formation and Plasticity in Hippocampus
Authors: Boda Bernadett , Alberi Stefano , Nikonenko Irina , Node-Langlois Roxanne , Jourdain Pascal , Moosmayer Marlyse , Parisi-Jourdain Lorena , Muller Dominique
Published: December 2004

Mutations of the gene coding for PAK3 (p21-activated kinase 3) are associated with X-linked, nonsyndromic forms of mental retardation (MRX) in which the only distinctive clinical feature is the cognitive deficit. The mechanisms through which PAK3 mutation produces the mental handicap remain unclear, although an involvement in the mechanisms that regulate the formation or plasticity of synaptic networks has been proposed. Here we show, using a transient transfection approach, that antisense and small interfering RNA-mediated suppression of PAK3 or expression of a dominant-negative PAK3 carrying the human MRX30 mutation in rat hippocampal organotypic slice cultures results in the formation of abnormally elongated dendritic spines and filopodia-like protrusions and a decrease in mature spine synapses. Ultrastructural analysis of the changes induced by expression of PAK3 carrying the MRX30 mutation reveals that many elongated spines fail to express postsynaptic densities or contact presynaptic terminals. These defects are associated with a reduced spontaneous activity, altered expression of AMPA-type glutamate receptors, and defective long-term potentiation. Together, these data identify PAK3 as a key regulator of synapse formation and plasticity in the hippocampus and support interpretations that these defects might contribute to the cognitive deficits underlying this form of mental retardation.
Chronic Exposure to Rotenone Models Sporadic Parkinson's Disease inDrosophila melanogaster
Authors: Coulom Hélène , Birman Serge
Published: December 2004

Parkinson's disease (PD) is a movement disorder characterized by the selective degeneration of nigrostriatal dopaminergic neurons. Both familial and sporadic cases present tremor, rigidity, slowness of movement, and postural instability. Although major insights into the genes responsible for some rare hereditary cases have arisen, the etiology of sporadic cases remains unknown. Epidemiological studies have suggested an association with environmental toxins, mainly mitochondrial complex I inhibitors such as the widely used pesticide rotenone. In recent years,Drosophila melanogasterhas been used as a model of several neurodegenerative diseases, including a genetic model of PD. Here, we studied the neurodegenerative and behavioral effects of a sublethal chronic exposure to rotenone inDrosophila. After several days, the treated flies presented characteristic locomotor impairments that increased with the dose of rotenone. Immunocytochemistry analysis demonstrated a dramatic and selective loss of dopaminergic neurons in all of the brain clusters. The addition ofl-dopa (3,4-dihydroxy-l-phenylalanine) into the feeding medium rescued the behavioral deficits but not neuronal death, as is the case in human PD patients. In contrast, the antioxidant melatonin (N-acetyl-5-methoxytryptamine) alleviated both symptomatic impairment and neuronal loss, supporting the idea that this agent may be beneficial in the treatment of PD. Therefore, chronic exposure to pesticides recapitulates key aspects of PD inDrosophilaand provides a newin vivomodel for studying the mechanisms of dopaminergic neurodegeneration.
Isolation of a Novel Platelet-Derived Growth Factor-Responsive Precursor from the Embryonic Ventral Forebrain
Authors: Chojnacki Andrew , Weiss Samuel
Published: December 2004

Oligodendrocyte progenitor cells express platelet-derived growth factor (PDGF) receptor-α and, when expanded in PDGF only, have been shown to generate oligodendrocytes and astrocytes but never neurons. Recent evidence suggests that oligodendrocytes are generated by a common progenitor that also generates neurons but not astrocytes. We used the neurosphere culture system to isolate embryonic ventral forebrain, PDGF-responsive precursors (PRPs). We report that the medial ganglionic eminence is the source of PRP-generated neurospheres and that the progeny can differentiate into parvalbumin-positive interneurons, oligodendrocytes, and astrocytes. Thyroid hormone and bone morphogenetic protein-2 (BMP-2) promote the mutually exclusive differentiation of oligodendrocytes and neurons, respectively, whereas ciliary neurotrophic factor acts with BMP-2 to suppress OLIG2 expression and promote astroglial differentiation. PRPs require fibroblast growth factor-2 together with PDGF to maintain self-renewal, which is dependent on sonic hedgehog signaling. We present evidence for forebrain oligodendrocytes and parvalbumin-positive interneurons being generated by a common precursor and elucidate signals regulating the multiple differentiation routes of the progeny of this precursor.
Cellular Mechanisms Associated with Spontaneous and Ciliary Neurotrophic Factor-cAMP-Induced Survival and Axonal Regeneration of Adult Retinal Ganglion Cells
Authors: Park Kevin , Luo Jian-Min , Hisheh Susan , Harvey Alan R. , Cui Qi
Published: December 2004

We have shown previously that intraocular elevation of cAMP using the cAMP analog 8-(4-chlorophenylthio)-cAMP (CPT-cAMP) failed to promote axonal regeneration of axotomized adult retinal ganglion cells (RGCs) into peripheral nerve (PN) grafts but significantly potentiated ciliary neurotrophic factor (CNTF)-induced axonal regeneration. Using the PN graft model, we now examine the mechanisms underlying spontaneous and CNTF/CPT-cAMP-induced neuronal survival and axonal regrowth. We found that blockade of the cAMP pathway executor protein kinase A (PKA) using the cell-permeable inhibitor KT5720 did not affect spontaneous survival and axonal regeneration but essentially abolished the CNTF/CPT-cAMP-induced RGC survival and axonal regeneration. Blockade of CNTF signaling pathways such as phosphotidylinositol 3-kinase (PI3K)/akt by 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) by 2-(2-diamino-3-methoxyphenyl-4H-1-benzopyran-4-one (PD98059), or Janus kinase (JAK)/signal transducer and activators of transcription (STAT3) by tyrphostin AG490 also blocked the CNTF/CPT-cAMP-dependent survival and regeneration effects. PKA activity assay and Western blots showed that KT5720, LY294002, and PD98059 almost completely inhibited PKA, PI3K/akt, and MAPK/ERK signal transduction, respectively, whereas AG490 substantially decreased JAK/STAT3 signal transduction. Intraocular injection of CPT-cAMP resulted in a small PKA-dependent increase in CNTF receptor α mRNA expression in the retinas, an effect that may facilitate CNTF action on survival and axonal regeneration. Surprisingly, in the absence of CNTF/CPT-cAMP, LY294002, PD98059, and AG490, but not KT5720, significantly enhanced spontaneous RGC survival, suggesting differential roles of these pathways in RGC survival under different conditions. Our data suggest that CNTF/CPT-cAMP-induced RGC survival and axonal regeneration are a result of multiple pathway actions, with PKA as an essential component, but that these pathways can function in an antagonistic manner under different conditions.
Cytometric analyses to distinguish death processes.
Authors: Gorczyca W
Published: December 2004

The morphological changes typical of apoptosis, as well as the loss of integrity of the plasma membrane and the breakdown of nuclear DNA provide numerous features that permit recognition of apoptotic cell death by various methods. Flow cytometry (FCM) and laser scanning cytometry (LSC) allow for accurate and rapid measurement of apoptosis in both cultures and clinical samples (e.g. solid tumors, bone marrow aspirates, peripheral blood etc.). Furthermore, both FCM and LSC enable one to correlate the apoptosis with the position of the dying cell in the cell cycle. Discussion includes the cytometric identification and quantitation of apoptotic or necrotic cells, based on the analysis of a particular biochemical or molecular feature that is characteristic for either necrosis or apoptosis.
Aromatase and breast cancer susceptibility.
Authors: Probst-Hensch N M , Ingles S A , Diep A T , Haile R W , Stanczyk F Z , Kolonel L N , Henderson B E
Published: December 2004

Based on experimental and epidemiological evidence it is hypothesized that estrogen increases breast cancer risk by increasing mitotic activity in breast epithelial cells. Aromatase is crucial to the biosynthesis of estrogens and may therefore play a role in breast cancer development. Supporting data for an etiological role of aromatase in breast tumor biology are several-fold. First, the association between weight and postmenopausal breast cancer risk may be mediated by aromatase. Secondly, a pilot study found a higher aromatase expression in normal breast adipose tissue from breast cancer cases as opposed to healthy women. Thirdly, experimental data in animals suggest that aromatase activity predisposes mammary tissue to preneoplastic and neoplastic changes. In a multiethnic cohort study conducted in Los Angeles and on Hawaii we investigated (i) whether the plasma estrone to androstenedione (E1/A) ratio in different ethnic groups was associated with ethnic differences in breast cancer incidence, and (ii) whether genetic variation in the CYP19 gene encoding the P450 aromatase protein was associated with breast cancer risk. The age- and weight-adjusted ethnic specific E1/A ratios x 100 among women without oophorectomy were 7.92 in African-Americans, 8.22 in Japanese, 10.73 in Latinas and 9.29 in non-Latina Whites (P=0.09). The high E1/A ratio in Latina women was not associated with a high breast cancer incidence; in fact Latina women had the lowest breast cancer incidence in the cohort observed so far. We found no consistent association of an intronic (TTTA)n repeat polymorphism with breast cancer risk in different ethnic groups. This polymorphism was not associated with differences in the plasma E1/A ratio in a way that would predict its functional relevance. We describe a newly identified TTC deletion in intron 5 of the CYP19 gene that is associated with the (TTTA)n repeat polymorphism. Neither this polymorphism, nor a polymorphism at codon 264 in exon VII of the CYP19 gene, was associated with breast cancer. We did not identify any genetic variation in exon VIII in 54 African-American subjects. We identified rare genetic variants of unknown functional relevance in the promoter 1.4 of the CYP19 gene in 3 out of 24 Latina women. Further investigation into the role of aromatase in breast cancer etiology is important, given that the potential use of aromatase inhibitors as breast cancer chemopreventives depends on these results.
Combined treatment with the 5 alpha-reductase inhibitor PNU 157706 and the antiandrogen flutamide on the Dunning R3327 prostatic carcinoma in rats.
Authors: Zaccheo T , Giudici D , di Salle E
Published: December 2004

The steroid 5 alpha-reductase enzyme catalyzes the conversion of testosterone to the potent androgen 5 alpha-dihydrotestosterone (DHT). PNU 157706, a novel, potent and selective dual 5 alpha-reductase inhibitor, was reported to be effective in inhibiting the growth of established tumors in the Dunning R3327 rat prostatic carcinoma model. We have studied the efficacy of combined treatment with PNU 157706 and the antiandrogen flutamide in this prostatic tumor in rats. Rats with tumor diameters of about 1 cm were treated orally 6 days a week for 9 weeks with PNU 157706 (10 mg/kg per day) alone or in combination with flutamide (1 and 5 mg/kg per day). Animals were killed 24 h after the last treatment and ventral prostates were removed for testosterone and DHT determination. PNU 157706 reduced the growth of established tumors by 36%; flutamide showed a slight effect at 1 mg/kg per day (24% inhibition), while at the dose of 5 mg/kg per day it reduced tumor growth by 48%. The combination of PNU 157706 with the lower dose of flutamide caused an additive tumor growth inhibition (60%) and the combination with the higher dose of flutamide resulted in a better inhibition of tumor growth (68%) than did either treatment alone. Castration resulted in marked tumor growth inhibition (76%). Ventral prostate weight was more markedly reduced by PNU 157706 treatment than by flutamide; combined treatment was as effective as castration. Prostatic DHT content was markedly reduced by PNU 157706 (93%), whereas prostatic testosterone increased (137%). Concomitant treatment with flutamide partially antagonized the testosterone increase induced by PNU 157706 and did not modify the already considerable suppression of DHT. These data show that the inhibitory effects of PNU 157706 and flutamide on Dunning prostatic tumor growth are additive, thus supporting the rationale of this combination therapy in advanced prostate cancer, in order to achieve adequate androgen blockade with minimal side-effects.
Apoptosis in mammary gland and cancer.
Authors: Kumar R , Vadlamudi R K , Adam L
Published: December 2004

Homeostasis in normal tissue is regulated by a balance between proliferative activity and cell loss by apoptosis. Apoptosis is a physiological mechanism of cell loss that depends on both pre-existing proteins and de novo protein synthesis, and the process of apoptosis is integral to normal mammary gland development and in many diseases, including breast cancer. The mammary gland is one of the few organ systems in mammals that completes its morphologic development postnatally during two discrete physiologic states, puberty and pregnancy. The susceptibility of the mammary gland to tumorigenesis is influenced by its normal development, particularly during stages of puberty and pregnancy that are characterized by marked alterations in breast cell proliferation and differentiation. Numerous epidemiologic studies have suggested that specific details in the development of the mammary gland play a critical role in breast cancer risk. Mammary gland development is characterized by dynamic changes in the expression profiles of Bcl-2 family members. The expression of Bcl-2 family proteins in breast cancer is also influenced by estradiol and by progestin. Since the ratio of proapoptotic to antiapoptotic proteins determines apoptosis or cell survival, hormone levels may have important implications in the therapeutic prevention of breast cancer.
Overexpression of HER-2 as a resistance mechanism to hormonal therapy for breast cancer.
Authors: Dowsett M
Published: December 2004

Hormonal therapy leads to improved survival in oestrogen receptor (ER) positive early breast cancer and long-term responses in advanced disease. However, resistance to such therapy is a serious clinical problem. This article considers the data for and against there being a significant role for the oncogene HER-2 in such resistance. Transfection of HER-2 into MCF-7 cells leads to resistance to tamoxifen but data differ in relation to the oestrogen dependence of such cells. A number of retrospective studies have been conducted of HER-2 status in adjuvant trials of tamoxifen. Most of these also suggest a negative role but individually the studies do not have the statistical power to be conclusive. Recent studies in the neoadjuvant context have shown a significant antiproliferative effect of endocrine therapy in HER-2 positive/ER positive tumours but this is much less than in HER-2 negative/ER positive tumours. It is concluded that incomplete hormonal resistance results from co-expression of HER-2 and ER and that this may differ between different hormonal agents.
New approaches to surgery for breast cancer.
Authors: Singletary S E
Published: December 2004

The surgical management of breast cancer is rapidly evolving towards less invasive procedures. Alternative biopsy techniques, including fine-needle aspiration and core needle biopsy, are replacing excisional biopsy as the treatment standard. Breast conservation therapy is now widely used in place of mastectomy, both for small tumors and for larger tumors that have been downstaged through induction chemotherapy. Less invasive procedures for axillary treatment such as lymphatic mapping and sentinel lymph-node biopsy are being explored in an effort to avoid the morbidity associated with axillary lymph-node dissection. For women who still prefer or need to receive a mastectomy, immediate breast reconstruction with autologous tissue provides an excellent cosmetic outcome that is oncologically sound. This is especially appealing to high-risk women who opt to have a prophylactic mastectomy. High-risk women are also being offered the option of receiving chemopreventive treatment that may reduce their lifetime risk of cancer by almost 50%. These new, less invasive approaches require the close cooperation of a team of physicians,including surgeons, pathologists, radiologists, and medical and radiation oncologists.
Melatonin and mammary cancer: a short review.
Authors: S√°nchez-Barcel√≥ E J , Cos S , Fern√°ndez R , Mediavilla M D
Published: December 2004

Melatonin is an indolic hormone produced mainly by the pineal gland. The former hypothesis of its possible role in mammary cancer development was based on the evidence that melatonin down-regulates some of the pituitary and gonadal hormones that control mammary gland development and which are also responsible for the growth of hormone-dependent mammary tumors. Furthermore, melatonin could act directly on tumoral cells, as a naturally occurring antiestrogen, thereby influencing their proliferative rate. The first reports revealed a low plasmatic melatonin concentration in women with estrogen receptor (ER)-positive breast tumors. However, later studies on the possible role of melatonin on human breast cancer have been scarce and mostly of an epidemiological type. These studies described a low incidence of breast tumors in blind women as well as an inverse relationship between breast cancer incidence and the degree of visual impairment. Since light inhibits melatonin secretion, the relative increase in the melatonin circulating levels in women with a decreased light input could be interpreted as proof of the protective role of melatonin on mammary carcinogenesis. From in vivo studies on animal models of chemically induced mammary tumorigenesis, the general conclusion is that experimental manipulations activating the pineal gland or the administration of melatonin lengthens the latency and reduces the incidence and growth rate of mammary tumors, while pinealectomy usually has the opposite effects. Melatonin also reduces the incidence of spontaneous mammary tumors in different kinds of transgenic mice (c-neu and N-ras) and mice from strains with a high tumoral incidence. In vitro experiments, carried out with the ER-positive MCF-7 human breast cancer cells, demonstrated that melatonin, at a physiological concentration (1 nM) and in the presence of serum or estradiol: (a) inhibits, in a reversible way, cell proliferation, (b) increases the expression of p53 and p21WAF1 proteins and modulates the length of the cell cycle, and (c) reduces the metastasic capacity of these cells and counteracts the stimulatory effect of estradiol on cell invasiveness; this effect is mediated, at least in part, by a melatonin-induced increase in the expression of the cell surface adhesion proteins E-cadherin and beta(1)-integrin. The direct oncostatic effects of melatonin depends on its interaction with the tumor cell estrogen-responsive pathway. In this sense it has been demonstrated that melatonin down-regulates the expression of ERalpha and inhibits the binding of the estradiol-ER complex to the estrogen response element (ERE) in the DNA. The characteristics of melatonin's oncostatic actions, comprising different aspects of tumor biology as well as the physiological doses at which the effect is accomplished, give special value to these findings and encourage clinical studies on the possible therapeutic value of melatonin on breast cancer.
Estrogen and antiestrogen regulation of cell cycle progression in breast cancer cells.
Authors: Doisneau-Sixou S F , Sergio C M , Carroll J S , Hui R , Musgrove E A , Sutherland R L
Published: December 2004

The central involvement of estrogen in the development of the mammary gland and in the genesis of breast cancer has lent impetus to studies of the links between estrogen action and the cell cycle machinery. Recent studies of the estrogenic regulation of molecules with known roles in the control of G1/S phase progression have resulted in significant advances in understanding these links. Estrogens independently regulate the expression and function of c-Myc and cyclin D1 and the induction of either c-Myc or cyclin D1 is sufficient to recapitulate the effects of estrogen on cell cycle progression. These pathways converge at the activation of cyclin E-Cdk2 complexes. The active cyclin E-Cdk2 complexes are depleted of the cyclin dependent kinase (CDK) inhibitor p21(WAF1/CIP1) because of estrogen-mediated inhibition of nascent p21(WAF1/CIP1). Insulin and estrogen synergistically stimulate cell cycle progression, and the ability of estrogen to antagonize an insulin-induced increase in p21(WAF1/CIP1) gene expression appears to underlie this effect. Antiestrogen treatment of MCF-7 cells leads to an acute decrease of c-Myc expression, a subsequent decline in cyclin D1, and ultimately arrest of cells in a state with features characteristic of quiescence. An antisense-mediated decrease in c-Myc expression results in decreased cyclin D1 expression and inhibition of DNA synthesis, mimicking the effects of antiestrogen treatment and emphasizing the importance of c-Myc as an estrogen/antiestrogen target. These data identify c-Myc, cyclin D1, p21(WAF1/CIP1) and cyclin E-Cdk2 as central components of estrogen regulation of cell cycle progression and hence as potential downstream targets that contribute to the role of estrogen in oncogenesis.
Protein kinase C: a target for anticancer drugs?
Authors: Mackay H J , Twelves C J
Published: December 2004

Protein kinase C (PKC) is a family of serine/threonine kinases that is involved in the transduction of signals for cell proliferation and differentiation. The important role of PKC in processes relevant to neoplastic transformation, carcinogenesis and tumour cell invasion renders it a potentially suitable target for anticancer therapy. Furthermore, there is accumulating evidence that selective targeting of PKC may improve the therapeutic efficacy of established neoplastic agents and sensitise cells to ionising radiation. This article reviews the rationale for targeting PKC, focuses on its role in breast cancer and reviews the preclinical and clinical data available for the efficacy of PKC inhibition.
Genetics of neuroendocrine and carcinoid tumours.
Authors: Leotlela P D , Jauch A , Holtgreve-Grez H , Thakker R V
Published: December 2004

Neuroendocrine tumours (NETs) originate in tissues that contain cells derived from the embryonic neural crest, neuroectoderm and endoderm. Thus, NETs occur at many sites in the body, although the majority occur within the gastro-entero-pancreatic axis and can be subdivided into those of foregut, midgut and hindgut origin. Amongst these, only those of midgut origin are generally argentaffin positive and secrete serotonin, and hence only these should be referred to as carcinoid tumours. NETs may occur as part of complex familial endocrine cancer syndromes, such as multiple endocrine neoplasia type 1 (MEN1), although the majority occur as non-familial (i.e. sporadic) isolated tumours. Molecular genetic studies have revealed that the development of NETs may involve different genes, each of which may be associated with several different abnormalities that include point mutations, gene deletions, DNA methylation, chromosomal losses and chromosomal gains. Indeed, the foregut, midgut and hindgut NETs develop via different molecular pathways. For example, foregut NETs have frequent deletions and mutations of the MEN1 gene, whereas midgut NETs have losses of chromosome 18, 11q and 16q and hindgut NETs express transforming growth factor-alpha and the epidermal growth factor receptor. Furthermore, in lung NETs, a loss of chromosome 3p is the most frequent change and p53 mutations and chromosomal loss of 5q21 are associated with more aggressive tumours and poor survival. In addition, methylation frequencies of retinoic acid receptor-beta, E-cadherin and RAS-associated domain family genes increase with the severity of lung NETs. Thus the development and progression of NETs is associated with specific genetic abnormalities that indicate the likely involvement of different molecular pathways.
Somatostatin receptors in gastroentero-pancreatic neuroendocrine tumours.
Authors: de Herder W W , Hofland L J , van der Lely A J , Lamberts S W J
Published: December 2004

Five somatostatin receptor (sst) subtype genes, sst(1), sst(2), sst(3), sst(4) and sst(5), have been cloned and characterised. The five sst subtypes all bind natural somatostatin-14 and somatostatin-28 with high affinity. Endocrine pancreatic and endocrine digestive tract tumours also express multiple sst subtypes, but sst(2) predominance is generally found. However, there is considerable variation in sst subtype expression between the different tumour types and among tumours of the same type. The predominant expression of sst(2) receptors on pancreatic endocrine or carcinoid tumours is essential for the control of hormonal hypersecretion by the octapeptide somatostatin analogues such as octreotide and lanreotide. Somatostatin and its octapeptide analogues are also able to inhibit proliferation of normal and tumour cells. The high density of sst(2) or sst(5) on pancreatic endocrine or carcinoid tumours further allows the use of radiolabelled somatostatin analogues for in vivo visualisation. The predominant expression of sst(2) receptors in these tumours and the efficiency of sst(2) receptors to undergo agonist-induced internalisation is also essential for the application of radiolabelled octapeptide somatostatin analogues. Currently, [(111)In-DTPA(0)]octreotide, [(90)Y-DOTA(0),Tyr(3)]octreotide, [(177)Lu-DOTA(0)Tyr(3)]octreotate, [(111)In-DOTA(0)]lanreotide and [(90)Y-DOTA(0)]lanreotide can be used for this purpose.
Two somatic TSH receptor mutations in a patient with toxic metastasising follicular thyroid carcinoma and non-functional lung metastases.
Authors: F√ºhrer D , Tannapfel A , Sabri O , Lamesch P , Paschke R
Published: December 2004

In a 59-year-old patient, thyroid follicular cancer was diagnosed in two right-sided toxic thyroid nodules, which had presented clinically as unilateral thyroid autonomy. In addition, the patient had histologically proven lung metastases of thyroid cancer; however, these failed to exhibit iodine uptake and were resistant to radioiodine treatment. The functional activity of the thyroid nodules prompted us to screen for TSH receptor (TSHR) mutations, and the histological diagnosis of follicular carcinoma led us to search for the PAX8-PPARgamma1 rearrangement and mutations in the ras genes. Each thyroid nodule harboured a different TSHR mutation (large nodule, Asp633Tyr; small nodule, Phe631Ile). Presence of both mutations in one sample suggestive of local invasion of a thyroid carcinoma could not be demonstrated, although several specimens from different nodule locations were screened. Only the wild-type TSHR sequence was identified in the histologically normal left thyroid lobe, and no genetic alterations were found in the other investigated genes. No TSHR mutations were detected in the pulmonary metastases. This is the first case report of a patient with toxic follicular thyroid carcinoma harbouring two different TSHR mutations and presenting with non-functional lung metastases.
Genetically defined mouse models that mimic natural aspects of human prostate cancer development.
Authors: Roy-Burman P , Wu H , Powell W C , Hagenkord J , Cohen M B
Published: December 2004

This review is focused on mouse models for prostate cancer that have been designed on the basis of genetic alterations that are frequently found in human prostate cancer. It begins with an analysis of the similarities and differences in the gross and microscopic anatomy of the mouse and human prostate glands, and extends to the pathologies induced in the genetically manipulated mouse prostate in comparison with the sporadic development of the disease in humans. Major achievements have been made in modeling human prostate cancer in mice in recent years. There are models which display slow, temporal development of increasingly severe preneoplastic lesions, which are remarkably restricted to the prostate gland, a property similar to the aging-related progression of these lesions in humans. Other models rapidly progress to local invasive adenocarcinoma, and, in some of them metastasis is manifested subsequently with defined kinetics. Global assessment of molecular changes in the prostate of the genetically manipulated mice is increasingly underscoring the validity of the models through identification of 'signature' genes which are associated with the organ-confined primary or distant metastases of human prostate cancer. Taken together, various 'natural' models depicting stages of the disease, ranging from the early preneoplastic lesions to metastatic prostate cancer, now provide new tools both for exploring the molecular mechanism underlying prostate cancer and for development or testing of new targeted therapies.
Differential expression of menin in sporadic pituitary adenomas.
Authors: Theodoropoulou M , Cavallari I , Barzon L , D'Agostino D M , Ferro T , Arzberger T , Gr√ºbler Y , Schaaf L , Losa M , Fallo F , Ciminale V , Stalla G K , Pagotto U
Published: December 2004

Pituitary adenomas represent one of the key features of multiple endocrine neoplasia type 1. The gene involved in this syndrome (MEN1) is a putative tumor suppressor, that codes for a 610-amino acid nuclear protein termed 'menin'. Analyses of sporadic pituitary adenomas have so far failed to reveal MEN1 mutations or defects in MEN1 transcription in these tumors. In the present study we detected menin protein expression in a panel of normal and tumoral pituitary tissues, using a monoclonal antibody against the carboxy-terminus of menin. In the normal human pituitary gland, strong nuclear staining for menin was detectable in the majority of the endocrine cells of the anterior lobe, without a clear association with a particular hormone-producing type. In sporadic pituitary adenomas, menin expression was variable, with a high percentage of cases demonstrating a significant decrease in menin immunoreactivity when compared with the normal pituitary. Interestingly, metastatic tissues derived from one pituitary carcinoma had no detectable menin levels. Altogether, our data provide the first information regarding the status of menin expression in human normal and neoplastic pituitary as determined by immunohistochemistry (IHC).
Stable ‘portrait’ of breast tumors during progression: data from biology, pathology and genetics
Authors: Lacroix M , Toillon R-A , Leclercq G
Published: December 2004

It is widely believed that ductal breast cancer dissemination involves a succession of clinical and pathological stages starting with carcinoma in situ, progressing into invasive lesion and culminating in metastatic disease. Such changes have frequently been attributed to the sequential acquisition of various alterations in a single cell followed by clonal selection and expansion, thus leading to intra-tumor diversity. According to this multi-step view, extensive genotype and phenotype (marker expression, grade) shift may occur in the same tumor during progression; this may lead to the coexistence of molecularly and/or pathologically different areas within the same lesion. An increasing amount of data of various natures now appear to challenge this concept: only a few distinct ‘portraits’, in relation to estrogen receptor (ER) status and grade, may be found among tumors. Moreover, although undergoing increasing genetic alteration, most individual lesions largely maintain their phenotype when they evolve from in situ to the metastatic state. While many of the data presented here are related to ductal tumors, lobular cancer is also discussed.
Deletion of the mouse GH-binding protein (mGHBP) mRNA polyadenylation and splicing sites does not abolish production of mGHBP
Authors: Zhou Y , He L , Baumann G , Kopchick J J
Published: December 2004

In murine species, the GH receptor (mGHR) gene encodes a full-length membrane-anchored mGHR and a truncated soluble receptor ectodomain (the GH-binding protein; mGHBP). The mGHR and mGHBP mRNAs are generated by alternative pre-mRNA splicing. Similar GHR/GHBP pairs are generated in other species by proteolysis of the GHR. The regulation of GHBP expression and the biological role of GHBP are not clear. In order to begin to dissect the factors responsible for regulating expression of mGHR and mGHBP, we have cloned a mouse GH receptor/binding protein (mGHR/BP) minigene consisting of two mGHR cDNA fragments and an mGHR/BP genomic sequence, such that the mGHR and mGHBP can be derived from the minigene by mimicking native alternative pre-mRNA splicing. To study the possible role of selection of polyadenylation relative to the expression of mGHR and mGHBP, we deleted the two tandem poly A addition signals and the flanking AT-rich region within the exon (exon 8A) that encodes the carboxy terminus of mGHBP. In addition, two other mutated forms of the minigene, one containing a mutated alternative splice acceptor site (SAS) near exon 8A and the other possessing a deletion of the intron between exons 7 and 8A (intron 7/8A), were generated. Expression of the mGHR/BP minigene and its mutated forms in transfected mouse L cells revealed that removal of the polyadenylation signals diminished but did not abolish either mGHR or mGHBP production. However, mutation of the SAS yielded normal mGHR and an mGHBP which may be a result of the translation of an mRNA possessing an open reading frame in intron 7/8A. Additionally, removal of intron 7/8A abolished mGHR expression but resulted in mGHBP production. The results suggest that selection of alternative polyadenylation sites of the mGHR/BP gene does not play a major role in the regulation of expression of mGHR and mGHBP in vitro. These results also suggest that mutation of the SAS near exon 8A does not abolish the ability of mGHR/BP gene to produce an mGHBP that retains the ability to bind GH, although the new mGHBP may be different from the natural mGHBP at its carboxy terminus.
Cloning and characterization of goldfish activin type IIB receptor
Authors: Ge W , Tanaka M , Yoshikuni M , Eto Y , Nagahama Y
Published: December 2004

We have cloned a full length cDNA coding for the activin type IIB receptor (GactRIIB) from the goldfish ovary. GactRIIB shares 73 and 70% amino acid identity in the extracellular domain, and 78 and 80% identity in the intracellular domain with the type IIB receptors of the mouse and Xenopus respectively. The intracellular domain of GactRIIB contains two serine kinase consensus sequences, DFKSRN and GTRRYMAPE, in agreement with the reports in other vertebrates that serine/threonine phosphorylation is involved in activin signal transduction. The identity of GactRIIB was confirmed by transient expression in the COS cells followed by activin binding. Iodinated human activin A bound to the GactRIIB-transfected cells and the binding could be completely inhibited by unlabeled activin. Affinity labeling revealed a band of about 85 kDa, which is in agreement with the reported type II receptors in other vertebrates. Together with the fact that activin is expressed in the goldfish ovary, the cloning of activin receptors from the ovary suggests paracrine and autocrine roles for activin in the goldfish ovarian functions.
The nuclear orphan receptors COUP-TFII and Ear-2 act as silencers of the human oxytocin gene promoter
Authors: Chu K , Zingg HH
Published: December 2004

We have previously shown that COUP-TFII and Ear-2, two members of the nuclear orphan receptor family, are able to repress oestrogen-stimulated transcriptional activity of the human oxytocin (OT) gene promoter by binding to a site that overlaps with the oestrogen response element (ERE) present in the 5' flanking region of the gene. Although most nuclear receptor-mediated transcriptional repression conforms with the paradigm of passive repression and involves competitive binding to an activator site, active repression, i.e. silencing of basal promoter activity, has been observed in a limited number of cases. Here we show by co-transfection experiments using COUP-TFII and Ear-2 expression vectors and reporter constructs containing OT gene promoter fragments linked to the chloramphenicol acetyltransferase gene that both COUP-TFII and Ear-2 are capable of silencing basal OT gene promoter activity by 54 and 75% respectively. 5' Deletion and footprint analyses revealed two areas of functionally important interaction sites: (1) a direct TGACC(T/C) repeat overlapping the ERE and (2) a more promoter-proximal area centred at - 90 containing three imperfect direct repeats (R1-R3) spaced by four nucleotides each. Mutagenesis of reporter constructs as well as electrophoretic mobility-shift assays demonstrated that each of the three proximal repeats R1-R3 contributed to orphan receptor binding and the silencing effect. Inasmuch as the orphan receptor-binding sites are not involved in mediating basal transcriptional activity of the OT gene promoter, the observed effects are best interpreted as active repression or promoter silencing. Moreover, since COUP-TFII and Ear-2 are both co-expressed in OT-expressing uterine epithelial cells, the novel transcriptional effects described here are likely to be of functional importance in the fine-tuning of uterine OT gene expression in vivo.
The induction by estrogen of rat alpha 2u-globulin gene expression in mouse L-cells
Authors: Wang KS , Hodgetts RB , Addison WR
Published: December 2004

Expression of the rat alpha 2u-globulin gene family is regulated in the adult male liver by a number of hormones, including growth hormone, thyroid hormone and several steroids. Upon injection into ovariectomized females, estrogens first induce alpha 2u-globulin expression and then suppress this gene after several days of hormone administration. To study this phenomenon, we developed a mouse L-cell line that expressed the human estrogen receptor. High levels of rat alpha 2u-globulin transcript were induced in stable transfectants of this line carrying a cloned alpha 2u-globulin gene, following exposure to 17 beta-estradiol. Since this induction was inhibited by cycloheximide, the response to estrogen, as to other steroids, appears to be secondary. Using genes with variously deleted 5'-upstream regions, sequences responsible for this induction were located between -730 bp and -223 bp relative to the start of transcription. Examination of the DNA in this region revealed that an estrogen receptor element was located at -590 bp in an area that is highly conserved in most known alpha 2u-globulin genes. Administration of both dexamethasone and estrogen produced a synergistic effect in this system. The induction of alpha 2u-globulin RNA by estrogen in L-cells may re-capitulate the initial response to estrogen in vivo, and therefore represents a good model system to seek the identity of the other factors required to effect full induction.
Nuclear receptors: coactivators, corepressors and chromatin remodeling in the control of transcription
Authors: Collingwood TN , Urnov FD , Wolffe AP
Published: December 2004

A contemporary view of hormone action at the transcriptional level requires knowledge of the transcription factors including the hormone receptor that may bind to promoters or enhancers, together with the chromosomal context within which these regulatory proteins function. Nuclear receptors provide the best examples of transcriptional control through the targeted recruitment of large protein complexes that modify chromosomal components and reversibly stabilize or destabilize chromatin. Ligand-dependent recruitment of transcriptional coactivators destabilizes chromatin by mechanisms including histone acetylation and contacts with the basal transcriptional machinery. In contrast, the recruitment of corepressors in the absence of ligand or in the presence of hormone antagonists serves to stabilize chromatin by the targeting of histone deacetylases. Both activation and repression require the action of other chromatin remodeling engines of the switch 2/sucrose non-fermentable 2 (SWI2/SNF2) class. Here we summarize this information and integrate hormone action into a chromatin context.
Overlap of IGF- and heparin-binding sites in rat IGF-binding protein-5
Authors: Song H , Beattie J , Campbell IW , Allan GJ
Published: December 2004

Using site-directed mutagenesis, we have undertaken a study of a potential IGF-binding site in the C-terminal domain of rat IGFBP-5, lying close to or within a previously described heparin-binding domain (residues 201-218) in this protein. After analysis of binding activity using three different methods - ligand blotting, solution phase equilibrium binding and biosensor measurement of real-time on- and off-rates - we report that the mutation of two highly conserved residues within this region (glycine 203 and glutamine 209) reduces the affinity of the binding protein for both IGF-I and IGF-II, while having no effect on heparin binding. In addition, we confirm that mutation of basic residues within the heparin-binding domain (R201L, K202E, K206Q and R214A) results in a protein that has attenuated heparin binding but shows only a small reduction in affinity for IGF-I and -II. Previous findings have described the reduction in affinity of IGFBP-5 for IGFs that occurs after complexation of the binding protein with heparin or other components of the extracellular matrix (ECM) and have postulated that such an interaction may result in conformational changes in protein structure, affecting subsequent IGF interaction. Our data suggesting potential overlap of heparin- and IGF-binding domains argue for a more direct effect of ECM modulation of the affinity of IGFBP-5 for ligand by partial occlusion of the IGF-binding site after interaction with ECM.