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P J Fuller

Publications and source records attributed to P J Fuller.

At least 19 recordsLinked to original sources
PubMed2002

FSH-regulated gene expression profiles in ovarian tumours and normal ovaries.

Development, growth and function of the ovary are controlled by endocrine and paracrine signals. These may also influence the development of ovarian cancer. The aim of this study was to identify the key molecular markers of the unregulated growth and hormone synthesis seen in ovarian tumours, particularly in granulosa cell tumours (GCT). Genes used in this study were chosen on the basis of our understanding of growth and differentiation in the normal ovary. We sought to define the patterns of gene expression in a panel of epithelial and stromal ovarian tumours. Expression was determined by RT-PCR using gene-specific primers for the FSH receptor (FSHR); the FSH early response genes: regulatory subunit of protein kinase A (RII-beta), cyclin D2 (cycD2) and sgk; and late response markers: cyclooxygenase-2 (COX-2) and the LH receptor (LHR). The GCT had high expression of FSHR compared with normal ovaries and the other tumours. cycD2 and RII-beta and COX-2 genes were also highly expressed in the GCT. sgk and LHR expression was lower in all of the tumours than in normal ovaries. Serous cystadenocarcinomas also had an unexpectedly high expression of COX-2. Comparison of the gene expression profiles between each tumour group suggests a molecular phenotype for GCT that is similar to that reported for FSH stimulated pre-ovulatory granulosa cells.

Adult↗
PubMed2001

The inhibins and ovarian cancer.

Interest in inhibin as a marker of ovarian malignancy was stimulated by the description of elevated immunoreactive inhibin levels in the sera of patients with granulosa cell tumours. Several groups have confirmed the value of serum inhibin in the diagnosis and follow-up of patients with this uncommon malignancy. Immunoreactive inhibin levels are also frequently elevated in patients with mucinous cystadenocarcinoma and less frequently in other forms of ovarian tumour. Assay of sera using the specific dimeric inhibin assays has shown that ovarian tumours are able to secrete dimeric inhibin particularly inhibin B. The less specific alpha-subunit directed assays, however, most frequently show elevated concentrations. Used in combination with CA125 as a dual tumour marker, it appears in principle that inhibin can be a useful diagnostic agent. Immunohistochemistry for the inhibin subunits has been reported with increasing frequency as a helpful method to assess suspected ovarian stromal cell tumours. Its diagnostic accuracy for other types of ovarian adenocarcinoma appears less reliable. Expression of the inhibin subunit mRNAs has been demonstrated in a variety of ovarian malignancies. The observation that inhibin levels are elevated in ovarian cancer has stimulated studies of their relevance to the molecular pathogenesis of these malignancies. Findings to date have been largely negative with no evidence for activating mutations of the FSH receptor or of the post-receptor signalling pathway proteins.

Biomarkers, Tumor↗
PubMed2001

11th International Congress of Endocrinology.

The Olympics of endocrinology, the 11th International Congress of Endocrinolgy was held rather appropriately in Sydney, four weeks after the summer games of the XXWIIth Modern Olympiad. Both occasions were a great success and whilst it may be tempting to extend the analogy to the pool or the track or heaven forbid, digress into 'drugs in sport', this review will focus on endocrinology. There were over 3000 participants with ten plenary lectures, 20 meet-the-expert sessions, 41 symposia, 128 oral free communications and 1500 posters. Sydney post-Olympics provided a vibrant, exciting and picturesque setting with outstanding convention facilities. The Congress Party was held at Campbells Cove in the lee of the Harbour Bridge looking toward the Opera House which provided an opportunity for delegates to view the two architectural icons that had become so familiar in the preceding months. Credit must be given both to the Local Organising Committee of Sydney endocrinologists who made it all happen and to the International Program Organising Committee who crafted a pageant of first rate endocrinology. It is self-evident that this report can only hope to give the reader a flavour of a Congress such as this with the choice of topics being largely idiosyncratic. With five concurrent symposia and two concurrent orals each morning and afternoon of the four days, any omissions reflect not on the topic or its importance but on this reviewer's inability to be in more than one place at once!

Animals↗
PubMed2001

Human kallikrein 4 (KLK4) is highly expressed in serous ovarian carcinomas.

Previous studies indicated that a new member of the human kallikrein (KLK) gene family, KLK4, was expressed in prostate, breast, and endometrial carcinoma cell lines and may have potential as a tumor marker. The aim of this study was to examine the expression of KLK4 in the normal ovary and ovarian tumors of different histology, stage, and differentiation and to determine its association with ovarian tumor progression. Using reverse transcription-PCR, Southern blot, and densitometry analyses, we found the level of KLK4 expression was higher in late stage serous (SER) epithelial-derived ovarian carcinomas than in normal ovaries, mucinous epithelial tumors, and granulosa cell tumors. KLK4 was highly expressed in all of the SER ovarian carcinoma cell lines (eight of eight), SER epithelial carcinomas (11 of 11), and two adenomas, whereas it was expressed at a lower level (or not at all) in normal ovaries (four of six), mucinous epithelial tumors (three of four), endometrioid carcinomas (four of five), clear cell carcinomas (two of three), or granulosa cell tumors (three of six). Of particular interest, KLK4 mRNA variants were detected in SER ovarian carcinoma cell lines and primary cultured ovarian tumor cells, but they were not present in normal ovaries. In situ hybridization analysis showed that KLK4 mRNA transcripts are localized to adenocarcinoma cells of ovarian tumor tissues. Similarly, immunohistochemical staining of ovarian carcinoma sections showed immunoreactivity to KLK4 protein product (hK4) antipeptide antibodies. In addition, intracellular hK4 levels, as detected on Western blot analysis, were induced by 100 nM estrogen treatment of the estrogen receptor positive ovarian carcinoma cell line OVCAR-3, >8-24 h. Our results show that the level of KLK4 expression and expression of KLK4 mRNA variants are associated with progression of ovarian cancer, particularly late stage SER adenocarcinomas. Moreover, hK4 may be a candidate marker for the diagnosis and/or monitoring of ovarian epithelial carcinomas.

Amino Acid Sequence↗
PubMed2000

Rapid upregulation of serum and glucocorticoid-regulated kinase (sgk) gene expression by corticosteroids in vivo.

The molecular mechanisms by which corticosteroids regulate epithelial sodium transport remain to be fully elucidated. Expression of the serum and glucocorticoid-regulated kinase (sgk) has recently been reported to be regulated acutely by corticosteroids in the amphibian A6 cell line and in cortical collecting tubule cells in vitro. In order to extend this observation to a mammalian system in vivo, the acute response of the sgk gene to a single parenteral dose of aldosterone or dexamethasone was examined in the rat kidney and distal colon. The sgk mRNA levels were significantly elevated by both steroids by 30 min in the distal colon, reaching a peak at 2 h. A more modest increase in sgk mRNA levels was also seen in the kidney in response to both steroids. In both tissues, sgk mRNA has a very short half-life. As for other corticosteroid-regulated genes, the response appears to be mediated by both the mineralocorticoid and glucocorticoid receptors. The response to aldosterone in the distal colon in the presence of cycloheximide was superinduced, strongly suggesting that this is a primary response. The responses to both adrenalectomy and carbenoxolone sodium treatment suggest that the observed responses to corticosteroids can occur in the physiological range of endogenous circulating corticosteroids. These studies provide strong evidence that sgk is an aldosterone-induced gene in vivo in a mammalian system.

Aldosterone↗
PubMed2000

Acute differential regulation by corticosteroids of epithelial sodium channel subunit and Nedd4 mRNA levels in the distal colon.

The molecular mechanisms by which corticosteroids affect fluid and electrolyte balance have yet to be fully elucidated. The apical amiloride-sensitive electrogenic epithelial sodium channel (ENaC) has been shown to have a central role in corticosteroid-mediated sodium transport in the distal colon. The acute response of the alpha-, beta- and gammaENaC subunit genes to a single parenteral dose of aldosterone or dexamethasone was examined in the rat distal colon in vivo. The response of the Nedd4 gene, whose product is involved in channel turnover, was also examined. Whilst the alphaENaC and Nedd4 genes showed no significant response to either steroid, both the beta- and gammaENaC mRNA levels were increased acutely by both aldosterone and dexamethasone. The gammaENaC mRNA appears to have a very short half-life. Use of the highly selective glucocorticoid receptor agonist RU28362 confirmed that the response was mediated by both the mineralocorticoid and glucocorticoid receptors.

Adrenal Cortex Hormones↗
PubMed2000

Mineralocorticoid action.

The physiology of mineralocorticoid action, particularly with respect to epithelial sodium transport, is well defined. A full understanding of the molecular basis of mineralocorticoid action has however proven to be more elusive. In the last decade insights into structural and functional aspects of the mineralocorticoid receptor combined with emerging details of the components of the mediators of the sodium flux has resulted in a clearer picture. This review focuses on two aspects of these new developments; the mineralocorticoid receptor and putative aldosterone induced proteins.

Aldosterone↗
PubMed2000

Humoral factors in intestinal adaptation.

The small bowel has a remarkable ability to adapt after injury, inflammation or resection. It has long been suggested that humoral factors, particularly enteroglucagon, epidermal growth factor, neurotensin and growth hormone/insulin-like growth factor I, might stimulate bowel growth. Of particular interest is the recent finding that glucagon-like peptide 2 (GLP-2), a product of the gene encoding proglucagon, exerts a trophic effect on the intestinal epithelium via a specific G-protein-coupled receptor. GLP-2 and/or these other trophic peptides might prove to have a role in the treatment of bowel diseases associated with structural or functional loss of the small bowel.

Adaptation, Physiological↗
PubMed2000

Specificity in mineralocorticoid versus glucocorticoid action.

The mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR) share considerable structural and functional homology. Overlapping effects on epithelial sodium transport are observed in vivo; in vitro, both are able to bind and transactivate through a common hormone response element. This has led several investigators to suggest that specificity is conferred primarily by prereceptor mechanisms, and we have addressed this question using both in vitro and in vivo approaches. Although the MR has been regarded as less transcriptionally active than the GR in vitro, significant differences are observed when epithelial rather than fibroblast cell lines are used. These differences are mediated by the N-termini of the receptors. Activation of intracellular signaling pathways differentially modulates MR- versus GR-mediated transactivation. Although these studies identify mechanisms by which specificity may be achieved, they do not prove that this occurs in vivo. Such studies have been limited by an absence of MR-regulated genes. Known candidate aldosterone-responsive genes have been examined in the rat distal colon; the time course and the specificity of the response to a single parenteral dose of corticosteroid has been characterized. The epithelial sodium channel beta and gamma subunit genes are both up-regulated within 60 minutes by either MR or GR activation. Similar responses are observed for the serum and glucocorticoid-regulated kinase and channel-inducing factor genes. All four genes show clear and rapid up-regulation of their mRNA levels by aldosterone, which is paralleled by GR-mediated up-regulation of expression. While they are indeed aldosterone-responsive genes, genes that are uniquely aldosterone-regulated remain to be identified.

Animals↗
PubMed2000

The distribution of cells containing estrogen receptor-alpha (ERalpha) and ERbeta messenger ribonucleic acid in the preoptic area and hypothalamus of the sheep: comparison of males and females.

We have used in situ hybridization to compare the distributions of estrogen receptor alpha (ERalpha) and ERbeta messenger RNA (mRNA)-containing cells in the preoptic area and hypothalamus of ewes and rams. Perfusion-fixed brain tissue was collected from luteal phase ewes and intact rams (n = 4) during the breeding season. Matched pairs of sections were hybridized with sheep-specific, 35S-labeled riboprobes, and semiquantitative image analysis was performed on emulsion-dipped slides. A number of sex differences were observed, with females having a greater density of labeled cells than males (P < 0.001) and a greater number of silver grains per cell (P < 0.01) in the ventromedial nucleus for both ER subtypes. In addition, in the retrochiasmatic area, males had a greater (P < 0.05) cell density for ERalpha mRNA-containing cells than females, whereas in the paraventricular nucleus, females had a greater density (P < 0.05) of ERalpha mRNA-containing cells than males. There was a trend (P = 0.068) in the arcuate nucleus for males to have a greater number of silver grains per cell labeled for ERalpha mRNA. In both sexes, there was considerable overlap in the distributions of ERalpha and ERbeta mRNA-containing cells, but the density of labeled cells within each nucleus differed in a number of instances. Nuclei that contained a higher (P < 0.001) density of ERalpha than ERbeta mRNA-containing cells included the preoptic area, bed nucleus of the stria terminalis, and ventromedial nucleus, whereas the subfornical organ (P < 0.001), paraventricular nucleus (males only, P < 0.05), and retrochiasmatic nucleus (females only, P < 0.05) had a greater density of ERalpha than ERbeta mRNA-containing cells. The anterior hypothalamic area and supraoptic nucleus had similar densities of cells containing both ER subtypes. The lateral septum and arcuate nucleus contained only ERalpha, whereas only ERbeta mRNA-containing cells were seen in the zona incerta. The sex differences in the populations of ER mRNA-containing cells in the ventromedial and arcuate nuclei may explain in part the sex differences in the neuroendocrine and behavioral responses to localized estrogen treatment in these nuclei. Within sexes, the differences between the distributions of ERalpha and ERbeta mRNA-containing cells may reflect differential regulation of the actions of estrogen in the sheep hypothalamus. Low levels of ERbeta mRNA in the preoptic area and ventromedial and arcuate nuclei, regions known to be important for the regulation of reproduction, suggest that ERbeta may not be involved in these functions.

Animals↗
PubMed2000

Estrogen receptor isoform gene expression in ovarian stromal and epithelial tumors.

The factors involved in the pathogenesis of ovarian cancers remain unclear, and the response of these tumors to hormonal therapy is limited. The identification of a second estrogen receptor gene (ERbeta), expressed predominantly in ovarian granulosa cells, led us to explore its possible role in ovarian cancer, particularly in granulosa cell tumors (GCT). Several isoforms of ERbeta have been identified. We sought to define the patterns of both ERalpha and ERbeta gene expression in a panel of ovarian tumors consisting of GCT and serous and mucinous cystadenocarcinomas as well as in normal ovary. Expression was determined by RT-PCR using gene- and isoform-specific primers and probes combined with Southern blot analysis of the PCR products. Widespread expression of ERalpha was observed in all tumor types, but at relatively low levels. ERbeta is expressed predominantly in GCT, with lower levels in mucinous tumors and very low levels in serous tumors. The ERbeta2 splice variant previously reported in rodents was not observed. Only very low levels of the exon 5, exon 6, and exon 5/6 deletion variants were detected. The C-terminal truncation variant ERbeta(cx), however, exhibited widespread expression across all the tumor types. As ERbeta(cx) has been shown to be a ligand-independent antagonist of ERalpha action, the relative ratios of ERbeta(cx), ERalpha, and ERbeta may influence the response of a tumor to antiestrogen therapy.

Adult↗
PubMed1999

Structural determinants of aldosterone binding selectivity in the mineralocorticoid receptor.

The structural determinants of aldosterone binding specificity in the mineralocorticoid receptor (MR) have not been determined. The MR has greatest sequence identity with the better characterized glucocorticoid receptor (GR), which is reflected in their overlapping ligand binding specificities. There must be subtle sequence differences that can account for the MR-specific binding of aldosterone and the shared binding of cortisol. To characterize ligand binding specificity, chimeras were made between the human MR and GR ligand-binding domains (LBDs). Three points were chosen as break points to generate a total of 16 different constructs. These chimeric LBDs were placed in a human GR expression vector containing the GR DNA-binding and N-terminal domains and assayed by co-transfection into CV-1 cells with the mouse mammary tumor virus-luciferase reporter plasmid. Binding of [(3)H]aldosterone and [(3)H]dexamethasone was also measured. All of the constructs that are potently activated by aldosterone contain amino acids 804-874 of the MR. The results of the ligand binding experiments using [(3)H]aldosterone were consistent with the transactivation assay. Cortisol activation of the chimeras was surprisingly complex. Constructs that are activated by cortisol contain either amino acids 804-874 and 932-984 of the MR or amino acids 598-668 and 726-777 of the GR. However, all of the chimeras retained the ability to bind the synthetic glucocorticoid [(3)H]dexamethasone, and cortisol was able to displace [(3)H]dexamethasone binding, suggesting that the differential effects of cortisol on transcriptional activation are caused by an effect that occurs downstream of ligand binding. These results identify a subregion of the MR LBD that confers specificity of aldosterone binding, which contrasts with cortisol binding where differential effects between chimeras appear to be mediated by interactions distal to ligand binding.

Aldosterone↗
PubMed1999

Inhibin subunit gene expression in ovarian cancer.

OBJECTIVE(S): Granulosa cell tumors (GCT) and mucinous cystadenocarcinoma of the ovary are associated with elevated circulating levels of immunoreactive inhibin. Measurement of serum inhibin levels provides a useful tumor marker in the management of ovarian tumors. Inhibin is a dimeric ovarian glycoprotein hormone consisting of one alpha and one of two beta subunits. The beta subunits can dimerize to form activin. Activin is bound and its action modulated by another gonadal peptide, follistatin. In this study the patterns of expression of the three inhibin subunit genes, the follistatin gene, and the activin receptor type II gene have been determined. METHODS: Gene expression was analyzed in RNA prepared from 16 primary ovarian tumors using reverse transcriptase-polymerase chain reaction (RT-PCR). Gene-specific primes were used for RT-PCR; the products were analyzed by Southern blot analysis with gene-specific 32P-labeled probes. RESULTS: Widespread expression of these genes was found in all of the tumor types examined. Abundant expression of the inhibin alpha subunit gene was observed in the GCT and to a lesser extent in the mucinous and serous tumors. beta subunit expression was also present in the GCT and to a lesser extent in the other tumors. Widespread expression of both the activin receptor type II and the follistatin genes was also observed. CONCLUSIONS: Expression of the inhibin subunit genes in GCT and some epithelial tumors confirms that these tumors are the source of the increased immunoreactive inhibin seen in the circulation of patients with ovarian tumors. Expression of the activin receptor type II and follistatin genes suggests a paracrine role for activin in these tumors which may be modulated by follistatin, particularly in the GCT.

Activin Receptors, Type II↗
PubMed1999

mRNA levels of dipeptidyl peptidase IV decrease during intestinal adaptation.

BACKGROUND: Glucagon-like peptide 2 (GLP-2) has recently been shown to be a potent enterotrophic factor that may mediate mucosal hyperplasia during intestinal adaptation. The intestinal brush-border protease dipeptidyl peptidase IV (DPP IV) cleaves GLP-2 to an inactive form. It has been postulated that DPP IV activity limits the enterotrophic activity of GLP-2 in rats and humans. Massive small bowel resection (MSBR) in rats is an animal model of intestinal adaptation that has been used successfully to characterize factors involved in the modulation of adaptation. METHODS: Total RNA was extracted from normal terminal ileum or terminal ileum post-MSBR from Sprague-Dawley rats which were sacrificed 2, 4, and 7 days postresection. A partial rat DPP IV clone was isolated by reverse transcription polymerase chain reaction, and Northern blot analysis of rat DPP IV mRNA levels in normal small bowel and small bowel post-MSBR was performed. RESULTS: Within normal small bowel, DPP IV mRNA levels were greatest in the terminal ileum; levels in the duodenum and jejunum were approximately 50% of those in the terminal ileum. DPP IV mRNA levels decreased in terminal ileum post-MSBR 2, 4, and 7 days after resection. CONCLUSION: The decreased DPPIV gene expression suggests a novel mechanism by which the effects on mucosal growth of GLP-2 may be further enhanced, and further that GLP-2 may be a more useful therapeutic agent in humans than currently anticipated.

Adaptation, Physiological↗
PubMed1999

Cushing's syndrome secondary to ectopic ACTH secretion from metastatic breast carcinoma.

Breast carcinoma is a rare cause of ectopic ACTH syndrome. There are only two previously reported cases in which ACTH secretion is documented. We describe the case of a 56-year-old woman who presented with clinical and biochemical features of ectopic ACTH syndrome in the setting of metastatic breast carcinoma. Despite aggressive management of her ectopic ACTH syndrome, her course was complicated by opportunistic infection, respiratory failure and death. Immunostaining of the breast metastases for ACTH was positive and in situ hybridization revealed proopiomelanocortin gene expression. This is the first reported case of ectopic ACTH syndrome associated with metastatic breast cancer in which the technique of in situ hybridization has been used to confirm the breast cancer metastases as the source of ectopic ACTH secretion.

ACTH Syndrome, Ectopic↗
PubMed1999

Acute regulation by corticosteroids of channel-inducing factor gene messenger ribonucleic acid in the distal colon.

The molecular mechanisms by which corticosteroids affect fluid and electrolyte balance are unclear. Though glucocorticoid-responsive genes have been identified, genes regulated by aldosterone have not. CHIF (channel-inducing factor gene) is a recently identified gene that is up-regulated in the distal colon by chronic corticosteroid exposure, is expressed in the kidney, and induces a K+-specific current in Xenopus oocytes. The predicted protein shows similarity to gammaNa.K-ATPase, phospholemman, and Mat-8; all seem to be involved in ion transport. CHIF thus presents as a potential aldosterone target gene. In this study, CHIF expression was examined in rats in the acute timeframe of 0.5-4 h after corticosteroid administration. CHIF messenger RNA showed up-regulation by both mineralocorticoid and glucocorticoid receptor agonists in the distal colon, which was not diminished by cycloheximide. Corticosteroid regulation was not observed in the kidney. Basal and induced expression was absent in the lung and in all gastrointestinal tissues except colon, with expression increasing proximal to distal. CHIF is the first gene to show acute regulation by aldosterone and thus encodes a candidate aldosterone-induced protein. In addition, gammaNa.K-ATPase gene expression was found to be very low in colon and significantly higher in kidney. Regulation by corticosteroids was not evident in either tissue.

Adrenal Cortex Hormones↗
PubMed1999

[Inhibin and ovarian cancer].

Previous observations from our laboratory have demonstrated that the levels of immunoreactive inhibin (ir-inh) are elevated in almost all patients with granulosa cell tumors and in the majority of postmenopausal women with mucinous ovarian cancers. The present report confirms these findings in a larger group of post-menopausal women. Immunohistochemistry for the inhibin alpha. beta A and beta B sununits shows predominantly epithelial staining in granulosa cell tumors and in the majority of mucinous cancers. Serous cystadenocarcinomas also frequently show positive staining. Studies seeking to identify G alpha i-2 or FSH receptor mutations have provided negative results in contrast to other reports. Further studies of the roles of the inhibin-related family of peptides in ovarian cancer diagnosis and monitoring are clearly indicated.

Adenocarcinoma, Mucinous↗