Comparing medication adherence in patients receiving bisphosphonates for preventing fragility fractures: a comprehensive systematic review and network meta-analysis.

BACKGROUND: Bisphosphonates are effective in preventing fragility fractures; however, high rates of adherence are needed to preserve clinical benefits. OBJECTIVE: To investigate persistence and compliance to oral and intravenous bisphosphonates (alendronate, ibandronate, risedronate, and zoledronate). METHODS: Searches of 12 databases, unpublished sources, and trial registries were conducted, covering the period from 2000 to April 2021. Screening, data extraction, and risk of bias assessment (Cochrane Collaboration risk-of-bias tool 1.0 & ROBINS-I) were independently undertaken by two study authors. Randomised controlled trials (RCTs) and observational studies that used prescription claim databases or hospital medical records to examine patients' adherence were included. Network meta-analyses (NMA) embedded within a Bayesian framework were conducted, investigating users' likelihood in discontinuing bisphosphonate treatment. Where meta-analysis was not possible, data were synthesised using the vote-counting synthesis method. RESULTS: Fifty-nine RCTs and 43 observational studies were identified, resulting in a total population of 2,656,659 participants. Data from 59 RCTs and 24 observational studies were used to populate NMAs. Zoledronate users were the least likely to discontinue their treatment HR = 0.73 (95%CrI: 0.61, 0.88). Higher rates of compliance were observed in those receiving intravenous treatments. The paucity of data and the heterogeneity in the reported medication possession ratio thresholds precluded a NMA of compliance data. CONCLUSIONS: Users of intravenously administered bisphosphonates were found to be the most adherent to treatment among bisphosphonates' users. Patterns of adherence will permit the more precise estimation of clinical and cost-effectiveness of bisphosphonates. TRIAL REGISTRATION: PROSPERO 2020 CRD42020177166.

Pituitary metastases: presentation and outcomes from a pituitary center over the last decade.

PURPOSE: Highlight and characterize manifestations, diagnostic/management approaches and outcomes in a contemporary cohort of patients with pituitary metastases (PM) from a large European pituitary center-over 10 years. METHODS: Retrospective review of PM cases between 1/2009 and 12/2018. Clinical, laboratory, imaging data at PM detection and during follow-up were analysed. RESULTS: 18 cases were identified (14 females; median age at diagnosis 61.5 years). Most common primary malignancies were lung (39%) and breast (32%). Most frequent presenting manifestation was visual dysfunction (50%). Gonadotrophin, ACTH, TSH deficiency were diagnosed in 85%, 67%, 46% of cases, respectively; diabetes insipidus (DI) was present in 17%. 33% of cases were detected during investigation for symptoms unrelated to PM. PM management included radiotherapy (44%), transsphenoidal surgery (17%), transsphenoidal surgery and radiotherapy (6%) or monitoring only (33%). One-year survival was 49% with median survival from PM detection 11 months (range 2-47). CONCLUSIONS: In our contemporary series, clinical presentation of PM has evolved; we found increased prevalence of anterior hypopituitarism, decreased rates of DI and longer survival compared with older literature. Increased availability of diagnostic imaging, improvements in screening and recognition of pituitary disease and longer survival of patients with metastatic cancer may be contributing factors.

Screening for high hip fracture risk does not impact on falls risk: a post hoc analysis from the SCOOP study.

A reduction in hip fracture incidence following population screening might reflect the effectiveness of anti-osteoporosis therapy, behaviour change to reduce falls, or both. This post hoc analysis demonstrates that identifying high hip fracture risk by FRAX was not associated with any alteration in falls risk. INTRODUCTION: To investigate whether effectiveness of an osteoporosis screening programme to reduce hip fractures was mediated by modification of falls risk in the screening arm. METHODS: The SCOOP study recruited 12,483 women aged 70-85 years, individually randomised to a control (n = 6250) or screening (n = 6233) arm; in the latter, osteoporosis treatment was recommended to women at high risk of hip fracture, while the control arm received usual care. Falls were captured by self-reported questionnaire. We determined the influence of baseline risk factors on future falls, and then examined for differences in falls risk between the randomisation groups, particularly in those at high fracture risk. RESULTS: Women sustaining one or more falls were slightly older at baseline than those remaining falls free during follow-up (mean difference 0.70 years, 95%CI 0.55-0.85, p < 0.001). A higher FRAX 10-year probability of hip fracture was associated with increased likelihood of falling, with fall risk increasing by 1-2% for every 1% increase in hip fracture probability. However, falls risk factors were well balanced between the study arms and, importantly, there was no evidence of a difference in falls occurrence. In particular, there was no evidence of interaction (p = 0.18) between baseline FRAX hip fracture probabilities and falls risk in the two arms, consistent with no impact of screening on falls in women informed to be at high risk of hip fracture. CONCLUSION: Effectiveness of screening for high FRAX hip fracture probability to reduce hip fracture risk was not mediated by a reduction in falls.

Systematic screening using FRAX® leads to increased use of, and adherence to, anti-osteoporosis medications: an analysis of the UK SCOOP trial.

In the large community-based SCOOP trial, systematic fracture risk screening using FRAX® led to greater use of AOM and greater adherence, in women at high fracture risk, compared with usual care. INTRODUCTION: In the SCreening of Older wOmen for Prevention of fracture (SCOOP) trial, we investigated the effect of the screening intervention on subsequent long-term self-reported adherence to anti-osteoporosis medications (AOM). METHODS: SCOOP was a primary care-based UK multicentre trial of screening for fracture risk. A total of 12,483 women (70-85 years) were randomised to either usual NHS care, or assessment using the FRAX® tool ± dual-energy X-ray absorptiometry (DXA), with medication recommended for those found to be at high risk of hip fracture. Self-reported AOM use was obtained by postal questionnaires at 6, 12, 24, 36, 48 and 60 months. Analysis was limited to those who initiated AOM during follow-up. Logistic regression was used to explore baseline determinants of adherence (good ≥ 80%; poor < 80%). RESULTS: The mean (SD) age of participants was 75.6 (4.2) years, with 6233 randomised to screening and 6250 to the control group. Of those participants identified at high fracture risk in the screening group, 38.2% of those on treatment at 6 months were still treated at 60 months, whereas the corresponding figure for the control group was 21.6%. Older age was associated with poorer adherence (OR per year increase in age 0.96 [95% CI 0.93, 0.99], p = 0.01), whereas history of parental hip fracture was associated with greater rate adherence (OR 1.67 [95% CI 1.23, 2.26], p < 0.01). CONCLUSIONS: Systematic fracture risk screening using FRAX® leads to greater use of AOM and greater adherence, in women at high fracture risk, compared with usual care.

UK clinical guideline for the prevention and treatment of osteoporosis.

INTRODUCTION: In 2008, the UK National Osteoporosis Guideline Group (NOGG) produced a guideline on the prevention and treatment of osteoporosis, with an update in 2013. This paper presents a major update of the guideline, the scope of which is to review the assessment and management of osteoporosis and the prevention of fragility fractures in postmenopausal women and men age 50 years or over. METHODS: Where available, systematic reviews, meta-analyses and randomised controlled trials were used to provide the evidence base. Conclusions and recommendations were systematically graded according to the strength of the available evidence. RESULTS: Review of the evidence and recommendations are provided for the diagnosis of osteoporosis, fracture-risk assessment, lifestyle measures and pharmacological interventions, duration and monitoring of bisphosphonate therapy, glucocorticoid-induced osteoporosis, osteoporosis in men, postfracture care and intervention thresholds. CONCLUSION: The guideline, which has received accreditation from the National Institute of Health and Care Excellence (NICE), provides a comprehensive overview of the assessment and management of osteoporosis for all healthcare professionals who are involved in its management.

Delivering a quality-assured fracture liaison service in a UK teaching hospital-is it achievable?

UNLABELLED: To determine whether new national guidance on the specifications of a fracture liaison service are realistically deliverable, 1 year of data on the performance of such a service were audited. Audit targets were mostly met. This audit demonstrates that these standards are deliverable in a real world setting. INTRODUCTION: UK service specifications for a fracture liaison service (FLS) have been produced (National Osteoporosis Society, NOS) to promote effective commissioning and delivery of the highest quality care to patients with fragility fractures. How deliverable these standards are has not as yet been methodically reported. Our FLS was modelled on the ten NOS standards; performance was audited after 1 year to determine whether these standards could be delivered and to describe the lessons learnt. METHODS: Performance was audited against the NOS FLS Service Standards, with management based on the Fracture Risk Assessment Tool (FRAX®), the four-item Falls Risk Assessment Tool (FRAT), National Institute for Health and Care Excellence (NICE) and the National Osteoporosis Guideline Groups (NOGG) guidance. Data were recorded prospectively on a database. The FLS commenced in May 2014, was fully operational in August 2014 and data were captured from 1 September 2014 to 1 September 2015. RESULTS: The FLS detected 1773 patients and standards were largely achieved. Most, 94 %, patients were seen within 6 weeks, 533 DXA requests were generated, 804 outpatient FRAT assessments were recorded (134 required falls intervention) and 773 patients had bone treatments started. On follow-up at 3 months, between 78-79 % were still taking medication. CONCLUSIONS: Preliminary evaluation of a FLS implemented according to UK NOS standards demonstrates that the model is practical to apply to a large teaching hospital population. Collection and review of outcome and cost effectiveness data is required to determine the performance of this model in comparison with existing models.

A pragmatic randomised controlled trial of the effectiveness and cost-effectiveness of screening older women for the prevention of fractures: rationale, design and methods for the SCOOP study.

SCOOP is a UK seven-centre, pragmatic, randomised controlled trial with 5-year follow-up, including 11,580 women aged 70 to 85 years, to assess the effectiveness and cost-effectiveness of a community-based screening programme to reduce fractures. It utilises the FRAX algorithm and DXA to assess the 10-year probability of fracture. Introduction Osteoporotic, or low-trauma, fractures present a considerable burden to the National Health Service and have major adverse effects on quality of life, disability and mortality for the individual. Methods Given the availability of efficacious treatments and a risk assessment tool based upon clinical risk factors and bone mineral density, a case exists to undertake a community-based controlled evaluation of screening for subjects at high risk of fracture, under the hypothesis that such a screening programme would reduce fractures in this population. Results This study is a UK seven-centre, unblinded, pragmatic, randomised controlled trial with a 5-year follow-up period. A total of 11,580 women, aged 70 to 85 years and not on prescribed bone protective therapy will be consented to the trial by post via primary care providing 90% power to detect an 18% decrease in fractures. Conclusions Participants will be randomised to either a screening arm or control. Those undergoing screening will have a 10-year fracture probability computed from baseline risk factors together with bone mineral density measured by DXA in selected subjects. Individuals above an age-dependent threshold of fracture probability will be recommended for treatment for the duration of the trial. Subjects in the control arm will receive 'usual care'. Participants will be followed up 6 months after randomisation and annually by postal questionnaires with independent checking of hospital and primary care records. The primary outcome will be the proportion of individuals sustaining fractures in each group. An economic analysis will be carried out to assess cost-effectiveness of screening. A qualitative evaluation will be conducted to examine the acceptability of the process to participants.

Impact of UK National Guidelines based on FRAX®--comparison with current clinical practice.

OBJECTIVE: To assess whether clinician-determined treatment intervention thresholds are in line with the assessment of fracture risk provided by FRAX® and treatment recommendations provided by UK guidelines produced by the National Osteoporosis Guidelines Group (NOGG). DESIGN, PATIENTS AND MEASUREMENTS: This was a retrospective cohort analysis of 288 patients consecutively referred for dual-energy X-ray absorptiometry (DXA) scanning from primary care immediately prior to the introduction of the FRAX® algorithm. In addition to DXA assessment, patients completed a clinical risk factor questionnaire which included risk factors used in the FRAX® algorithm. Initial risk assessment and treatment decisions were performed after DXA. FRAX® was used, retrospectively, with femoral neck T-score, to estimate fracture risk which was applied to NOGG to generate guidance on treatment intervention. Clinician- and NOGG-determined outcomes were audited for concordance. RESULTS: There was concordance between clinician and NOGG treatment decisions in 215 (74.6%) subjects. Discordance was observed in 73 (25.3%) subjects. In the discordant group, seven subjects were given lifestyle advice when NOGG recommended treatment, 42 given treatment when NOGG recommended lifestyle advice only, and 24 were referred to a metabolic bone clinic for further evaluation. The reasons for treatment differences in subjects recommended treatment by clinician but not NOGG were largely (90.2%) attributed to the use of lumbar spine bone mineral density (BMD). CONCLUSIONS: There is high concordance between clinician-determined and FRAX®-NOGG intervention. The absence of spine BMD from FRAX® is the primary source of discrepancy. This study provides some assurance of the validity of the treatment thresholds generated from FRAX®-NOGG in 'real-world' usage.

Primary hyperparathyroidism--is mild disease worth treating?

Most patients with primary hyperparathyroidism (PHPT) are asymptomatic at presentation. This presents the dilemma whether to treat surgically or manage by conservative follow-up. This article covers the risks of managing mild PHPT conservatively. Some of these risks are well established, for example worsening of bone disease and increased risk of nephrolithiasis. Others, such as effects on cardiovascular function or the risk of malignancy are more controversial. These factors are critical to decisions relating to surgical or conservative management of mild PHPT.

Local and systemic glucocorticoid metabolism in inflammatory arthritis.

BACKGROUND: Isolated, primary synovial fibroblasts generate active glucocorticoids through expression of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). This enzyme produces cortisol from inactive cortisone (and prednisolone from prednisone). OBJECTIVE: To determine how intact synovial tissue metabolises glucocorticoids and to identify the local and systemic consequences of this activity by examination of glucocorticoid metabolism in patients with rheumatoid arthritis (RA). METHODS: Synovial tissue was taken from patients with RA during joint replacement surgery. Glucocorticoid metabolism in explants was assessed by thin-layer chromatography and specific enzyme inhibitors. RT-PCR and immunohistochemistry were used to determine expression and distribution of 11beta-HSD enzymes. Systemic glucocorticoid metabolism was examined in patients with RA using gas chromatography/mass spectrometry. RESULTS: Synovial tissue synthesised cortisol from cortisone, confirming functional 11beta-HSD1 expression. In patients with RA, enzyme activity correlated with donor erythrocyte sedimentation rate (ESR). Synovial tissues could also convert cortisol back to cortisone. Inhibitor studies and immunohistochemistry suggested this was owing to 11beta-HSD2 expression in synovial macrophages, whereas 11beta-HSD1 expression occurred primarily in fibroblasts. Synovial fluids exhibited lower cortisone levels than matched serum samples, indicating net local steroid activation. Urinary analyses indicated high 11beta-HSD1 activity in untreated patients with RA compared with controls and a significant correlation between total body 11beta-HSD1 activity and ESR. CONCLUSIONS: Synovial tissue metabolises glucocorticoids, the predominant effect being glucocorticoid activation, and this increases with inflammation. Endogenous glucocorticoid production in the joint is likely to have an impact on local inflammation and bone integrity.

A haemangiopericytoma of the ethmoid sinus causing oncogenic osteomalacia: a case report and review of the literature.

Oncogenic osteomalacia is a rare cause of osteomalacia. It is caused by a tumour which is generally benign. These tumours, when identified, are often found in the head and neck region. The case is reported here of a haemangiopericytoma isolated in the ethmoid sinus, and the literature regarding tumours at this site is reviewed. Including the present case there are five reported in the world literature of an ethmoid sinus tumour causing oncogenic osteomalacia. The treatment for this disease is excision of the mass, which is where the head and neck specialist's expertise is required.

PTTG's C-terminal PXXP motifs modulate critical cellular processes in vitro.

Human pituitary tumor-transforming gene (PTTG), known also as securin, is a multifunctional protein implicated in the control of mitosis and the pathogenesis of thyroid, colon, oesophageal and other tumour types. Critical to PTTG function is a C-terminal double PXXP motif, forming a putative SH3-interacting domain and housing the gene's sole reported phosphorylation site. The exact role of phosphorylation and PXXP structure in the modulation of PTTG action in vitro remains poorly understood. We therefore examined the mitotic, transformation, proliferation and transactivation function of the C-terminal PXXP motifs of human PTTG. Live-cell imaging studies using an EGFP-PTTG construct indicated that PTTG's regulation of mitosis is retained regardless of phosphorylation status. Colony-formation assays demonstrated that phosphorylation of PTTG may act as a potent inhibitor of cell transformation. In proliferation assays, NIH-3T3 cells stable transfected and overexpressing mutations preventing PTTG phosphorylation (Phos-) showed significantly increased [3H]thymidine incorporation compared with WT, whereas mutants mimicking constitutive phosphorylation of PTTG (Phos+) exhibited reduced cell proliferation. We demonstrated that PTTG transactivation of FGF-2 in primary thyroid and PTTG-null cell lines was not affected by PTTG phosphorylation but was prevented by a mutant disrupting the PXXP motifs (SH3-). Taken together, our data suggest that PXXP structure and phosphorylation are likely to exert independent and critical influences upon PTTG's diverse actions in vitro.

A potential role for PTTG/securin in the developing human fetal brain.

Human securin, known also as PTTG, has established oncogenic and cell cycle regulatory functions. PTTG/securin transforms cells in vitro, inhibits sister chromatid separation, and regulates secretion of fibroblast growth factor-2. FGF-2 is a key regulator of CNS development and PTTG/securin expression has been reported in murine fetal brain. We examined the expression and function of securin and FGF-2 in the developing human fetal brain and in a fetal neuronal cell line (NT 2). Securin expression was significantly reduced in first and second trimester fetal cerebral cortex compared with adult cerebral cortex, where immunocytochemistry revealed intense securin staining in neuronal cell bodies. FGF-2 protein was concordantly lower in fetal cortex, whereas pretranslational expression of PTTG binding factor (PBF) was not significantly altered in fetal brain compared with adult. PCNA expression demonstrated that high securin levels in adult cortex were associated with absent cell proliferation. In NT-2 cells, securin stimulated FGF-2 expression, which could be abrogated by a carboxyl-terminal mutation. Low transient expression of securin resulted in a significant proliferative effect, whereas high levels of securin expression inhibited cell turnover. We propose a potential role for human PTTG/securin in modulating cell proliferation and FGF-2 expression during human neurogenesis.

11beta-hydroxysteroid dehydrogenases, cell proliferation and malignancy.

The enzymes 11beta-hydroxysteroid dehydrogenase type 1 and 2 (11beta-HSD1 and 2) have well-defined roles in the tissue-specific metabolism of glucocorticoids which underpin key endocrine mechanisms such as adipocyte differentiation (11beta-HSD1) and mineralocorticoid action (11beta-HSD2). However, in recent studies we have shown that the effects of 11beta-HSD1 and 2 are not restricted to distinct tissue-specific hormonal functions. Studies of normal fetal and adult tissues, as well as their tumor equivalents, have shown a further dichotomy in 11beta-HSD expression and activity. Specifically, most normal glucocorticoid receptor (GR)-rich tissues such as adipose tissue, bone, and pituitary cells express 11beta-HSD1, whereas their fetal equivalents and tumors express 11beta-HSD2. We have therefore postulated that the ability of 11beta-HSD1 to generate cortisol acts as an autocrine anti-proliferative, pro-differentiation stimulus in normal adult tissues. In contrast, the cortisol-inactivating properties of 11beta-HSD2 lead to pro-proliferative effects, particularly in tumors. This proposal is supported by experiments in vitro which have demonstrated divergent effects of 11beta-HSD1 and 2 on cell proliferation. Current studies are aimed at (1) characterizing the underlying mechanisms for a "switch" in 11beta-HSD isozyme expression in tumors; (2) defining the molecular targets for glucocorticoids as regulators of cell proliferation; (3) evaluating the potential for targeting glucocorticoid metabolism as therapy for some cancers. These and other issues are discussed in the present review.

Pituitary tumor transforming gene and fibroblast growth factor-2 expression: potential prognostic indicators in differentiated thyroid cancer.

Differentiated thyroid cancers are the most common endocrine cancers, but there are no reliable molecular markers of prognosis. Pituitary tumor transforming gene (PTTG) plays several potential roles in tumor initiation and progression, including regulating mitosis and stimulating expression of fibroblast growth factor (FGF)-2. Increased expression of PTTG has been demonstrated in follicular thyroid lesions, and expression of this oncogene has been identified as a potential prognostic marker in pituitary adenomas and colon carcinomas. We assessed the expression of PTTG and FGF-2 and its receptor FGF-R-1 in 27 differentiated thyroid cancers, and we compared this with expression in 11 normal thyroids, 25 multinodular goiters, and 13 Graves' disease specimens. We also examined the relationship between gene expression and clinical markers of tumor behavior. PTTG and FGF-2 were overexpressed in thyroid carcinomas (9.5-fold increase, P = 0.003, and 5.0-fold increase, P < 0.001, respectively) compared with normal thyroid. Increased FGF-2 mRNA expression was independently associated with the findings of lymph node invasion (R(2) = 0.71; P < 0.001) and distant metastasis (R(2) = 0.55; P = 0.009) at tumor presentation, after taking into account known prognostic factors such as age and gender of the patient and size and type of the tumor. High PTTG expression was independently associated with tumor recurrence (R(2) = 0.64; P = 0.003). We conclude that PTTG and FGF-2 expression are potential prognostic markers (and perhaps therapeutic targets) for differentiated thyroid cancer.

Abnormal expression of 11 beta-hydroxysteroid dehydrogenase type 2 in human pituitary adenomas: a prereceptor determinant of pituitary cell proliferation.

The physiological effects of glucocorticoids (GCs) are, at least in part, mediated by inhibition of cell proliferation. Two isozymes of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) interconvert cortisol (F) and inactive cortisone (E), and are thus able to modulate GC action at an autocrine level. Previously, we have demonstrated absent expression of 11 beta-HSD2 in normal pituitaries; however, in a small number of pituitary tumors analysed, 11 beta-HSD2 was readily demonstrable. Here we have used real-time RT-PCR to quantify expression of mRNA for 11 beta-HSD1 and 2 in 105 human pituitary tumors and have performed enzyme expression and activity studies in primary pituitary cultures. Overall, pituitary tumors expressed lower levels of 11 beta-HSDl mRNA compared with normals (0.2-fold, P<0.05). In contrast, expression of 11 beta-HSD2 mRNA was 9.8-fold greater in tumors than in normals (P<0.001). Enzyme assays showed significant 11 beta-HSD2 activity (71.9+/-22.3 pmol/h/mg protein (mean+/-s.d.)) but no detectable 11 beta-HSDl activity. Proliferation assays showed that addition of glycyrrhetinic acid (an 11 beta-HSD2 inhibitor) resulted in a 30.3+/-7.7% inhibition of cell proliferation. In summary, we describe a switch in expression from 11 beta-HSDl to 11 beta-HSD2 in neoplastic pituitary tissue. We propose that abnormal expression of 11 beta-HSD2 acts as a proproliferative prereceptor determinant of pituitary cell growth, and may provide a novel target for future tumor therapy.

Expression of pituitary tumour transforming gene (PTTG) and fibroblast growth factor-2 (FGF-2) in human pituitary adenomas: relationships to clinical tumour behaviour.

OBJECTIVE: Pituitary tumour transforming gene (PTTG) encodes a multifunctional protein that is implicated in initiating and perpetuating pituitary adenoma growth. PTTG appears to have key regulatory functions in determining control of many fundamental cellular events including mitosis, cell transformation, DNA repair and gene regulation. Several of these events are mediated through interactions with PTTG binding factor (PBF) and fibroblast growth factor-2 (FGF-2). Given this background, we have determined the expression of PTTG, PBF, FGF-2 and its receptor FGF-R-1 in a large cohort of pituitary adenomas and have sought associations between levels of gene expression and clinical markers of tumour behaviour. PATIENTS AND METHODS: We used real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analyses to measure PTTG, PBF, FGF-2 and FGF-R-1 expression in ex vivo pituitary tumours (N = 121). Clinical data, including accurate radiological assessment of tumour characteristics, were used to determine any associations between gene expression and tumour behaviour. RESULTS: PTTG was increased significantly (fivefold, P = 0.005) in adenomas compared with normal pituitaries. We also demonstrated that PBF was similarly raised in adenomas (sixfold, P = 0.0001), and was significantly correlated with PTTG expression. FGF-2 and its receptor FGF-R-1 were also raised in adenomas compared with normal pituitary tissue. Moreover, significantly enhanced expression of FGF-R-1 was observed in invasive adenomas compared with other pituitary tumours. CONCLUSIONS: Our data support a fundamental role for PTTG-mediated upregulation of FGF-2 signalling in pituitary tumorigenesis and growth, and suggest that receptor-mediated mechanisms of growth factor action may be critically important. Further prospective studies are required to determine whether measurement of FGF-R-1 mRNA will be of clinical use as a prognostic marker in patients with pituitary adenomas.

Vascular endothelial growth factor, its receptor KDR/Flk-1, and pituitary tumor transforming gene in pituitary tumors.

Pituitary tumorigenesis is a poorly understood process involving dysregulation of the cell cycle, proliferation, and angiogenesis. The novel securin pituitary tumor transforming gene (PTTG) disrupts cell division and stimulates fibroblast growth factor (FGF)-2-mediated angiogenesis. We investigated expression of the angiogenic vascular endothelial growth factor (VEGF) and its receptor KDR/Flk-1 in 103 human pituitary tumors, and we assessed functional relationships between these genes in vitro. Nonfunctioning tumors (n = 81) demonstrated markedly raised VEGF mRNA (3.2-fold, P < 0.05) and protein concentrations, compared with normal pituitaries (n = 10). KDR was also highly induced in nonfunctioning tumors (14-fold, P < 0.001, n = 78) as well as in the whole cohort of pituitary tumors, compared with normal pituitary samples (14-fold, P < 0.0001, n = 100). In vitro, PTTG induced VEGF, but not KDR, expression in fetal neuronal NT2 cells (2.7-fold, P < 0.001, n = 8), MCF-7 breast carcinoma cells (1.9-fold, P = 0.03, n = 10), and choriocarcinoma JEG-3 cells (P = 0.0002, n = 8). A mutated PTTG construct that cannot be phosphorylated showed identical VEGF up-regulation (2.9-fold, P < 0.001, n = 8) in NT2 cells, compared with wild-type PTTG, but a further mutated construct with abrogation of the key protein:protein interaction domain of PTTG resulted in a significant reduction in VEGF stimulation, compared with wild-type (0.37-fold reduction, P < 0.001, n = 8). FGF-2 findings mirrored those of VEGF, although antibody depletion of secreted FGF-2 in the cell medium failed to influence VEGF up-regulation by PTTG. Overall, our findings implicate altered VEGF and KDR signaling in pituitary tumorigenesis, and we propose that PTTG stimulation of FGF-2 and VEGF expression in the presence of up-regulated growth factor receptors may account for angiogenic growth and progression of human pituitary tumors.