Understanding the policy dynamics of COVID-19 in the UK: Early findings from interviews with policy makers and health care professionals

The UK government response to COVID-19 has been heavily criticised. We report witnesses’ perceptions of what has shaped UK policies and how these policies have been received by healthcare workers. Such studies are usually affected by hindsight. Here we deploy a novel prospective approach to capture real-time information.

We are historians, social scientists and biomedical researchers who study how societies cope with infectious disease. In February 2020 we began regular semi-structured calls with prominent members of policy communities, and health care professionals, to elicit their roles in, and reactions to, the pandemic response.

We report witnesses’ perceptions that personal protective equipment (PPE) stocks were too small, early warnings have not led to sufficiently rapid policy decisions, and a lack of transparency is sapping public trust. Significant successes include research mobilisation. The early experiences and reactions of our witnesses suggest important issues for investigation, notably a perception of delay in decision making.

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UK coronavirus response delayed after the alarm was raised.

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Politicians abdicated responsibility by their early ‘follow the science’ rhetoric.

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Science advice to policy making needs people who bridge the two worlds.

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Centralised responses wasted valuable local public health skills.

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Pandemic response needs to move faster than the infectious disease.

Prostaglandins and Bone

Prostaglandins (PGs) are highly bioactive fatty acids. PGs, especially prostaglandin E₂ (PGE₂), are abundantly produced by cells of both the bone-forming (osteoblast) lineage and the bone-resorbing (osteoclast) lineage. The inducible cyclooxygenase, COX-2, is largely responsible for most PGE₂ production in bone, and once released, PGE₂ is rapidly degraded in vivo. COX-2 is induced by multiple agonists - hormones, growth factors, and proinflammatory factors - and the resulting PGE₂ may mediate, amplify, or, as we have recently shown for parathyroid hormone (PTH), inhibit responses to these agonists. In vitro, PGE₂ can directly stimulate osteoblast differentiation and, indirectly via stimulation of RANKL in osteoblastic cells, stimulate the differentiation of osteoclasts. The net balance of these two effects of PGE₂ in vivo on bone formation and bone resorption has been hard to predict and, as expected for such a widespread local factor, hard to study. Some of the complexity of PGE₂ actions on bone can be explained by the fact that there are four receptors for PGE₂ (EP1-4). Some of the major actions of PGE₂ in vitro occur via EP2 and EP4, both of which can stimulate cAMP signaling, but there are other distinct signaling pathways, important in other tissues, which have not yet been fully elucidated in bone cells. Giving PGE₂ or agonists of EP2 and EP4 to accelerate bone repair has been examined with positive results. Further studies to clarify the pathways of PGE₂ action in bone may allow us to identify new and more effective ways to deliver the therapeutic benefits of PGE₂ in skeletal disorders.

Continuous PTH in Male Mice Causes Bone Loss Because It Induces Serum Amyloid A

Increased bone resorption is considered to explain why intermittent PTH is anabolic for bone but continuous PTH is catabolic. However, when cyclooxygenase-2 (COX2) is absent in mice, continuous PTH becomes anabolic without decreased resorption. In murine bone marrow stromal cells (BMSCs), serum amyloid A (SAA)3, induced in the hematopoietic lineage by the combination of COX2-produced prostaglandin and receptor activator of nuclear factor κB ligand (RANKL), suppresses PTH-stimulated osteoblast differentiation. To determine whether SAA3 inhibits the anabolic effects of PTH in vivo, wild-type (WT) and SAA3 knockout (KO) mice were infused with PTH. In WT mice, continuous PTH induced SAA3 and was catabolic for bone. In KO mice, PTH was anabolic, increasing trabecular bone, serum markers of bone formation, and osteogenic gene expression. In contrast, PTH increased all measurements associated with bone resorption, as well as COX2 gene expression, similarly in KO and WT mice. SAA1 and SAA2 in humans are likely to have analogous functions to SAA3 in mice. RANKL induced both SAA1 and SAA2 in human bone marrow macrophages in a COX2-dependent manner. PTH stimulated osteogenesis in human BMSCs only when COX2 or RANKL was inhibited. Addition of recombinant SAA1 or SAA2 blocked PTH-stimulated osteogenesis. In summary, SAA3 suppresses the bone formation responses but not the bone resorption responses to PTH in mice, and in the absence of SAA3, continuous PTH is anabolic. In vitro studies in human bone marrow suggest that SAA may be a target for enhancing the therapeutic effects of PTH in treating osteoporosis.

Spontaneous Glutamatergic Synaptic Activity Regulates Constitutive COX-2 Expression in Neurons: OPPOSING ROLES FOR THE TRANSCRIPTION FACTORS CREB (cAMP RESPONSE ELEMENT BINDING) PROTEIN AND Sp1 (STIMULATORY PROTEIN-1)

Burgeoning evidence supports a role for cyclooxygenase metabolites in regulating membrane excitability in various forms of synaptic plasticity. Two cyclooxygenases, COX-1 and COX-2, catalyze the initial step in the metabolism of arachidonic acid to prostaglandins. COX-2 is generally considered inducible, but in glutamatergic neurons in some brain regions, including the cerebral cortex, it is constitutively expressed. However, the transcriptional mechanisms by which this occurs have not been elucidated. Here, we used quantitative PCR and also analyzed reporter gene expression in a mouse line carrying a construct consisting of a portion of the proximal promoter region of the mouse COX-2 gene upstream of luciferase cDNA to characterize COX-2 basal transcriptional regulation in cortical neurons. Extracts from the whole brain and from the cerebral cortex, hippocampus, and olfactory bulbs exhibited high luciferase activity. Moreover, constitutive COX-2 expression and luciferase activity were detected in cortical neurons, but not in cortical astrocytes, cultured from wild-type and transgenic mice, respectively. Constitutive COX-2 expression depended on spontaneous but not evoked excitatory synaptic activity and was shown to be N-methyl-d-aspartate receptor-dependent. Constitutive promoter activity was reduced in neurons transfected with a dominant-negative cAMP response element binding protein (CREB) and was eliminated by mutating the CRE-binding site on the COX-2 promoter. However, mutation of the stimulatory protein-1 (Sp1)-binding site resulted in an N-methyl-d-aspartate receptor-dependent enhancement of COX-2 promoter activity. Basal binding of the transcription factors CREB and Sp1 to the native neuronal COX-2 promoter was confirmed. In toto, our data suggest that spontaneous glutamatergic synaptic activity regulates constitutive neuronal COX-2 expression via Sp1 and CREB protein-dependent transcriptional mechanisms.

Serum Amyloid A3 Secreted by Preosteoclasts Inhibits Parathyroid Hormone-stimulated cAMP Signaling in Murine Osteoblasts

Continuous parathyroid hormone (PTH) blocks its own osteogenic actions in marrow stromal cell cultures by inducing Cox2 and receptor activator of nuclear factor κB ligand (RANKL) in the osteoblastic lineage cells, which then cause the hematopoietic lineage cells to secrete an inhibitor of PTH-stimulated osteoblast differentiation. To identify this inhibitor, we used bone marrow macrophages (BMMs) and primary osteoblasts (POBs) from WT and Cox2 knock-out (KO) mice. Conditioned medium (CM) from RANKL-treated WT, but not KO, BMMs blocked PTH-stimulated cAMP production in POBs. Inhibition was reversed by pertussis toxin (PTX), which blocks Gαi/o activation. Saa3 was the most highly differentially expressed gene in a microarray comparison of RANKL-treated WT versus Cox2 KO BMMs, and RANKL induced Saa3 protein secretion only from WT BMMs. CM from RANKL-stimulated BMMs with Saa3 knockdown did not inhibit PTH-stimulated responses in POBs. SAA added to POBs inhibited PTH-stimulated cAMP responses, which was reversed by PTX. Selective agonists and antagonists of formyl peptide receptor 2 (Fpr2) suggested that Fpr2 mediated the inhibitory actions of Saa3 on osteoblasts. In BMMs committed to become osteoclasts by RANKL treatment, Saa3 expression peaked prior to appearance of multinucleated cells. Flow sorting of WT marrow revealed that Saa3 was secreted only from the RANKL-stimulated B220(-) CD3(-)CD11b(-/low) CD115(+) preosteoclast population. We conclude that Saa3 secretion from preosteoclasts, induced by RANKL in a Cox2-dependent manner, inhibits PTH-stimulated cAMP signaling and osteoblast differentiation via Gαi/o signaling. The induction of Saa3 by PTH may explain the suppression of bone formation when PTH is applied continuously and may be a new therapeutic target for osteoporosis.

Abstract 1171: Increased expression of PDK4 in bladder cancer cells

Introduction and Objectives. Cancer cells have a high rate of glucose metabolism due to an increased requirement for biomolecules and energy. In some solid tumors, cancer cells divert pyruvate to lactate even in the presence of oxygen (Warburg effect) providing a survival advantage in an acidic and anaerobic environment. Pyruvate dehydrogenase complex (PDC) catalyzes oxidative decarboxylation of pyruvate to acetyl-CoA and links glycolysis to energetic and anabolic functions of the tricarboxylic acid cycle. PDC activity is regulated by pyruvate dehydrogenase kinase (PDK) and pyruvate dehydrogenase phosphatase (PDP). In a laser capture, microarray pilot study we found PDK4 expression to be increased 33-fold in high-grade invasive vs low-grade bladder cancers. The aim of this study was to examine the expression of PDK and PDP genes in bladder cancer cells.

Methods. Bladder cancer (HTB2, HTB4, HTB5, HTB9, HT1376) and benign urothelial (UROtsa) cell lines were cultured in defined media. Total RNA was extracted and quantitative PCR performed. Cell numbers were counted using a Coulter counter. Cell cycle and apoptosis analyses were performed using fluorescence-activated cell sorting. Transient transfections with PDK4 gene specific siRNAs were performed.

Results. In the present study, PDK4 expression was increased (20-100 fold; p<0.01) in bladder tumor vs. benign cell lines. Expression of the other three PDK isoforms was increased 3-5 fold. Investigation of transcription factors known to regulate the expression of PDK4 revealed overexpression of PPARα (8-22 fold; p<0.05-0.001) and HIF1α (3.7 - 13.4 fold; p<0.01 only in HT1376). Expression of PDP1 and PDP2 was also assessed (0.4 - 2.2 fold, not significant). The ratio of PDK/PDP expression was found to be 101 (PDK4/PDP1) and 138 (PDK4/PDP2) for HTB9; 196 and 42 for HT1376; 94 and 50 for HTB5 and 57 and 26.3 for HTB4. To examine the impact of PDK4 inhibition, cells were treated with a known inhibitor, dichloroacetate (DCA), for 0-72 h. A significant decrease in cell number was detected in a dose dependent manner (10-50 mM). HTB2, a low grade cell line, showed a significant decline in cell number (70%) when incubated with 50 mM DCA for 72 h (p< 0.01). HTB5, a high-grade cell line with a higher PDK4 expression, had a greater decline (92%) with same treatment (p< 0.01). Further, we observed growth inhibition by cell count with siRNA knockdown of PDK4. Our preliminary data on cell cycle analysis showed an enhanced number of tumor cells in G1 phase and a decrease in S-phase.

Conclusions. PDK4 gene expression was found to be higher in bladder cancer cell lines. Both inhibition and knock down of PDK4 resulted in impaired cell growth with cell cycle arrest at the G1 phase. Taken together these data suggest that PDK4 may prove to be a novel therapeutic target in the management of bladder cancer.

Source of Funding. The Leo & Anne Albert Charitable Trust

Citation Format: Dharamainder Choudhary, Andrew Mikhalyuk, Carol Pilbeam, John Taylor. Increased expression of PDK4 in bladder cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1171. doi:10.1158/1538-7445.AM2015-1171

Cyclooxygenase-2 suppresses the anabolic response to PTH infusion in mice

We previously reported that the ability of continuously elevated PTH to stimulate osteoblastic differentiation in bone marrow stromal cell cultures was abrogated by an osteoclastic factor secreted in response to cyclooxygenase-2 (Cox2)-produced prostaglandin E₂. We now examine the impact of Cox2 (Ptgs2) knockout (KO) on the anabolic response to continuously elevated PTH in vivo. PTH (40 μg/kg/d) or vehicle was infused for 12 or 21 days in 3-mo-old male wild type (WT) and KO mice in the outbred CD-1 background. Changes in bone phenotype were assessed by bone mineral density (BMD), μCT and histomorphometry. PTH infusion for both 12 and 21 days increased femoral BMD in Cox2 KO mice and decreased BMD in WT mice. Femoral and vertebral trabecular bone volume fractions were increased in KO mice, but not in WT mice, by PTH infusion. In the femoral diaphysis, PTH infusion increased cortical area in Cox2 KO, but not WT, femurs. PTH infusion markedly increased trabecular bone formation rate in the femur, serum markers of bone formation, and expression of bone formation-related genes, growth factors, and Wnt target genes in KO mice relative to WT mice, and decreased gene expression of Wnt antagonists only in KO mice. In contrast to the differential effects of PTH on anabolic factors in WT and KO mice, PTH infusion increased serum markers of resorption, expression of resorption-related genes, and the percent bone surface covered by osteoclasts similarly in both WT and KO mice. We conclude that Cox2 inhibits the anabolic, but not the catabolic, effects of continuous PTH. These data suggest that the bone loss with continuously infused PTH in mice is due largely to suppression of bone formation and that this suppression is mediated by Cox2.

Prostaglandin E2 acts via bone marrow macrophages to block PTH-stimulated osteoblast differentiation in vitro

Intermittent PTH is the major anabolic therapy for osteoporosis while continuous PTH causes bone loss. PTH acts on the osteoblast (OB) lineage to regulate bone resorption and formation. PTH also induces cyclooxygenase-2 (COX-2), producing prostaglandin E2 (PGE(2)) that can act on both OBs and osteoclasts (OCs). Because intermittent PTH is more anabolic in Cox-2 knockout (KO) than wild type (WT) mice, we hypothesized COX-2 might contribute to the effects of continuous PTH by suppressing PTH-stimulated differentiation of mesenchymal stem cells into OBs. We compared effects of continuous PTH on bone marrow stromal cells (BMSCs) and primary OBs (POBs) from Cox-2 KO mice, mice with deletion of PGE(2) receptors (Ptger(4) and Ptger(2) KO mice), and WT controls. PTH increased OB differentiation in BMSCs only in the absence of COX-2 expression or activity. In the absence of COX-2, PTH stimulated differentiation if added during the first week of culture. In Cox-2 KO BMSCs, PTH-stimulated differentiation was prevented by adding PGE(2) to cultures. Co-culture of POBs with M-CSF-expanded bone marrow macrophages (BMMs) showed that the inhibition of PTH-stimulated OB differentiation required not only COX-2 or PGE(2) but also BMMs. Sufficient PGE(2) to mediate the inhibitory effect was made by either WT POBs or WT BMMs. The inhibitory effect mediated by COX-2/PGE(2) was transferred by conditioned media from RANKL-treated BMMs and could be blocked by osteoprotegerin, which interferes with RANKL binding to its receptor on OC lineage cells. Deletion of Ptger(4), but not Ptger(2), in BMMs prevented the inhibition of PTH-stimulated OB differentiation. As expected, PGE(2) also stimulated OB differentiation, but when given in combination with PTH, the stimulatory effects of both were abrogated. These data suggest that PGE(2), acting via EP4R on BMMs committed to the OC lineage, stimulated secretion of a factor or factors that acted to suppress PTH-stimulated OB differentiation. This suppression of OB differentiation could contribute to the bone loss seen with continuous PTH in vivo.

How do they manage? A qualitative study of the realities of middle and front-line management work in health care

This project addressed three questions. First, how are middle management roles in acute care settings changing, and what are the implications of these developments? Second, how are changes managed following serious incidents, when recommendations from investigations are not always acted on? Third, how are clinical and organisational outcomes influenced by management practice, and what properties should an ‘enabling environment’ possess to support those contributions?

Data were gathered from around 1200 managers in six trusts through interviews, focus groups, management briefings, a survey with 600 responses, and serious incident case studies. For this project, ‘middle management’ meant any role below board level that included managerial responsibilities. Evidence provided by trust workforce information offices revealed that the management function is widely distributed, with > 30% of hospital staff holding either full-time management posts or ‘hybrid’ roles combining managerial with clinical or medical responsibilities. Hybrids outnumber full-time managers by four to one, but most have only limited management training, and some do not consider themselves to be managers. Management capabilities now at a premium include political skills, resilience, developing interprofessional collaboration, addressing ‘wicked problems’, performance management and financial skills.

Case study evidence reveals multiple barriers to the implementation of change following serious incidents. These barriers relate to the complex causes of most incidents, the difficulties in establishing and agreeing appropriate action plans and the subsequent problems of implementing ‘defensive’ change agendas. The conclusions from these case studies suggest that the management of serious incidents could potentially be strengthened by adding a change management perspective to the current organisational learning focus, by complementing root cause and timeline analysis methods with ‘mess mapping’ processes and by exploring opportunities to introduce systemic changes and high-reliability methods in addition to fixing the root causes of individual incidents.

Interview, focus group and survey evidence shows that middle managers are deeply committed but face increasing workloads with reduced resources, creating ‘extreme jobs’ with long hours, high intensity and fast pace. Such roles can be rewarding but carry implications for work–life balance and stress. Other pressures on middle management included rising patient and public expectations, financial challenges, burdensome regulation (external and internal), staffing problems, incompatible and dated information systems, resource and professional barriers to implementing change and problematic relationships with external agencies. Despite these pressures, management contributions included maintaining day-to-day performance, ‘firefighting’, ensuring a patient experience focus in decision-making, translating ideas into working initiatives, identifying and ‘selling’ new ideas, facilitating change, troubleshooting, leveraging targets to improve performance, process and pathway redesign, developing infrastructure (information technology, equipment, estate), developing others and managing external partnerships. Actions required to maintain an enabling environment to support those contributions would involve individual, divisional and organisational steps, most of which would be cost neutral.

Recommendations for future research concern the assessment of management capacity, the advantages and drawbacks of service-line organisation structures, the incidence and implications of extreme managerial jobs, evaluating alternative serious incident investigation methods, and the applicability of high-reliability organisation perspectives in acute care settings.

Funding

The National Institute for Health Research Health Services and Delivery Research programme.

Abstract 159: Macrophage Migration Inhibitory Factor (MIF) enhances proliferation and expression of tumorigenic cytokines in a bladder cancer cell line

Background: MIF is a proinflammatory cytokine with regulatory properties over tumor suppressor proteins involved in bladder cancer. We have previously reported that the absence of MIF in transgenic mice or the use of a small molecule oral inhibitor of MIF (CPSI-1306, Cytokine PharmaSciences, Inc, King of Prussia, PA) leads to decreased angiogenesis and invasive potential in the BBN mouse model of bladder cancer. The objective of this study was to evaluate potential pathways of MIF activity in a cell culture model. Methods: High grade, metastatic HTB-5 bladder cancer cells were treated with rhMIF 1-100 ng/ml (CPSI). Measurements included cell counts, proliferation by 3H-thymidine incorporation (TdR), phosphorylated and total ERK by Western analysis and mRNA expression of TNF-α, IL-6, VEGF and CD74 (putative receptor for MIF) by real time PCR. CPSI-1306 (0.5-500 nM) was tested for its ability to decrease ERK phosphorylation. Results: MIF 100 ng/ml increased cell counts 2-fold (p<0.01) on culture days 2-4. MIF increased TdR, normalized to cell numbers, 30% (p<0.01). MIF (1-100 ng/ml) stimulated ERK phosphorylation in a dose dependent manner, which was abrogated by the addition of CPSI-1306 at doses above 5 nM. A specific inhibitor of ERK (PD98059, 50 μm) blocked the MIF stimulated increase in cell number. MIF treatment for 24 hrs increased mRNA expression of the agiogenic factor VEGF and the cytokine TNF-α 2-fold (p<0.01). IL-6 mRNA was unchanged. mRNA levels for the putative MIF receptor, CD74, increased 1.3 fold with treatment (p=0.01). Conclusion: MIF increased ERK phosphorylation, which was blocked by CPSI-1306, a small molecule inhibitor of MIF. MIF also increased cell proliferation via an ERK pathway. These data, along with the increased cytokine expression, provide a potential explanation for the decreased angiogenesis and invasion seen in our in vivo murine models using global knockout of MIF or CPSI-1306. This study is the first to begin to elucidate mechanistic pathways involved in MIFs role in bladder cancer and possible pathways involved in CPSI-1306 inhibition. Funding Source: ACS MRSG-08-270-01-CCE, NIH RO1DK48361

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 159. doi:1538-7445.AM2012-159

Abstract 2407: Decreased inflammation and tumor stage in COX-2 knockout mice in the BBN model of bladder cancer

Introduction and Objective: Prostaglandins (PG) play a critical role in the development of solid tumors. Inhibition of cyclooxygenase-2 (COX-2), the committed step in PG synthesis, has been shown to impair tumor development in the BBN mouse model of bladder cancer. Because inhibitors of COX-2 have been reported to have anti-tumorigenic properties independent of COX-2, we evaluated the impact of gene disruption of COX-2 in the BBN mouse model.

Methods: We used 2 mo old male COX-2 knockout (KO) and wild type (WT) mice in an outbred CD-1 background. Mice were treated with (n=13-14 / group) and without (n=6/group) BBN in drinking water and euthanized after 25-27 wks. Bladders were harvested, weighed, bisected and step sectioned after formalin fixation. H&E stained sections were evaluated for pathologic stage/grade, percent involvement by invasive disease and degree of inflammatory infiltrate(grade 1-3).

Results: All animals receiving BBN had inflammatory changes at the time of euthanasia, with the grade being higher in WT (grade 2-3) than KO mice (grade 1-2). Six WT mice and 3 KO mice receiving BBN died, all within the first 18 wks of study, without gross evidence of tumor. Compared to previous studies with C57Bl/6 mice, tumor development was slower and burden was lower at 25-27 wks. All 7 BBN-treated WT mice had high grade invasive cancer at euthanasia: 6 pT1 and 1 pT3. Out of 11 BBN-treated KO mice at euthanasia, 10 had high grade cancer and 2 had invasive disease: 1 pT0, 6 CIS, 2 pTa (non-invasive) and 2 pT1. Mean bladder weight at euthanasia was elevated only in BBN-treated WT mice. There was a strong correlation between WT genotype and tumor stage by Pearson's R (0.74, p=0.03). The percent of tumor representing invasive disease was 0.31 in COX-2 WT mice vs 0.01 in KO mice (t-test, p=0.002).

Conclusions: Genetic disruption of COX-2 resulted in lower tumor stage and percent invasiveness in the BBN mouse model of bladder cancer. However, most COX-2 KO mice developed high grade disease, indicating disruption of COX-2 was not sufficient to prevent tumorigenesis. Reduced inflammation in the COX-2 KO mice may account for the decreased invasiveness.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2407. doi:10.1158/1538-7445.AM2011-2407

Abstract 2461: Gene deletion of mPGES-1 results in a significant reduction in tumor stage and burden in the BBN mouse model of bladder cancer

Introduction and Objective: Prostaglandins (PG) play a critical role in the development of solid tumors. Inhibition of cyclooxygenase-2 (COX-2), the committed step in PG synthesis, has been shown to impact tumor development in the BBN mouse model of bladder cancer. However, clinical translation has been impeded by the well documented cardiovascular problems with COX-2 inhibitors. Inhibition of other synthases downstream of COX-2 in the PG cascade may prove useful for chemoprevention or chemotherapy. In the following study, we evaluated the impact of gene deletion of membrane-associated prostaglandin synthase-1 (mPGES-1), the terminal synthase in the generation of PGE2, in the BBN mouse model.

Methods: Two month old male C57Bl/6 mice with global homozygous deletion for Ptges (mPGES-1 KO) and wild-type (WT) were treated with and without BBN in drinking water (n=5/grp) for 23 weeks. Bladders were harvested, weighed, fixed, step sectioned and evaluated by H&E for pathologic stage and grade and percent involvement of tissue by tumor. Urine was collected prior to sacrifice and evaluated for PGE-2 metabolites (PGEM) by ELISA.

Results: All animals had high-grade cancer at the time of euthanasia. WT bladders were significantly heavier than KO bladders (mean 0.18 vs 0.04 g respectively; p=0.03). Four of 5 WT mice had pT3 and one pT2 disease. Three of 5 KO mice had pT1 and 2 had pT2 disease. % tissue involvement was significantly less in the KO animals as well (54 vs 87%, p=0.03). Pearson's correlation for bladder weight and percent tumor involvement was 0.73 (p=0.02). Pathologic stage was dependant on genotype by Wilcoxon Rank Sum Test (p=0.02). Urine metabolites were reduced 50% in the KO compared to WT animals (mean 18.9 vs 45.2 pg/ml respectively; p<0.01).

Conclusions: Genetic deletion of mPGES-1 resulted in significant decreases in PGE-2 as evidenced by lower urinary PGEM and in pathologic stage and % tissue involvement by tumor. Increased bladder weights in the WT mice compared to KO mice were directly related to the increased tumor burden. These results suggest that inhibitors of mPGES-1 may prove to be an alternative to COX inhibition and possibly prove useful in the management of high-grade bladder cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2461.

Abstract 1549: Oral inhibitors of macrophage migratory inhibitory factor (MIF) lead to reduced tumor burden in a murine model of invasive bladder cancer

INTRODUCTION AND OBJECTIVES: MIF is a proinflammatory cytokine with regulatory properties over tumor suppressor proteins involved in bladder cancer. We have reported that absence of MIF in transgenic mice leads to decreased angiogenesis and invasion in the BBN model of bladder cancer. We evaluated the impact of 2 oral inhibitors of MIF (Cytokine PharmaSciences, King of Prussia, PA; CPSI) in the BBN model.

METHODS: 30, 3 mnth old male C57Bl/6 mice were treated with BBN 0.05% in drinking water for 22 wks. Mice (n=10/grp) received vehicle (PEG 300, methylcelluose), oral inhibitor CPSI-2705 or CPSI-1306 daily (25 mg/kg) by gavage from wks 16-22, corresponding to time of progression from CIS to invasive disease as determined in previous experiments. Animals were inspected daily for general health with weights recorded weekly. Bladders were weighed, fixed and assessed for tumor stage, grade, burden and associated angiogenesis.

RESULTS: In general, the group receiving CPSI-1306 appeared healthier during drug treatment. There was a 16% weight loss from the start of gavage in the control group vs 10-11% in the drug groups. Two animals each from the control and CPSI-2705 group died prior to study completion. The majority of control animals had evidence of upper tract obstruction with less noted in CPSI 2705 and none in the 1306 group. Average bladder weights were 0.5 ± 0.5 gm, 0.3 ± 0.3 gm and 0.2 ± 0.2 gm for control, 2705 and 1306 respectively which approached statistical significance for control vs 1306 (log transf p=0.06). There was a higher proportion of pT3 disease in the control (80%) vs inhibitor groups (60%). Tumor burden was markedly diminished in the drug groups (81% cntrl vs 62% 2705 vs 59% 1306, involvement invasive disease) with some bladders in these arms having only focal areas of invasion. Tumor grade trended lower in the drug groups as well.

CONCLUSIONS: The use of MIF oral inhibitors CPSI 2705 and CPSI 1306 in the BBN bladder cancer model resulted in less weight loss, improved general health, decreased tumor burden with a trend toward lower stage, grade and tumor associated angiogenesis. The results of this experiment warrant larger studies to validate and expand these findings with a goal of development for clinical use.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1549.

Effect of deletion of the prostaglandin EP2 receptor on the anabolic response to prostaglandin E2 and a selective EP2 receptor agonist

Studies using prostaglandin E receptor (EP) agonists indicate that prostaglandin (PG) E(2) can have anabolic effects through both EP4 and EP2 receptors. We previously found that the anabolic response to a selective EP4 receptor agonist (EP4A, Ono Pharmaceutical) was substantially greater than to a selective EP2 receptor agonist (EP2A) in cultured murine calvarial osteoblastic cells. To further define the role of the EP2 receptor in PG-mediated effects on bone cells, we examined the effects of EP2A and PGE(2) on both calvarial primary osteoblasts (POB) and marrow stromal cells (MSC) cultured from mice with deletion of one (Het) or both (KO) alleles of the EP2 receptor compared to their wild-type (WT) littermates. Deletion of EP2 receptor was confirmed by quantitative real-time PCR, Western blot and immunohistochemistry. The 1 month-old mice used to provide cells in these studies did not show any significant differences in their femurs by static histomorphometry. EP2A was found to enhance osteoblastic differentiation as measured by alkaline phosphatase mRNA expression and activity as well as osteocalcin mRNA expression and mineralization in the WT cell cultures from both marrow and calvariae. The effects were somewhat diminished in cultures from Het mice and abrogated in cultures from KO mice. PGE(2) effects were greater than those of EP2A, particularly in POB cultures and were only moderately diminished in Het and KO cell cultures. We conclude that activation of the EP2 receptor is able to enhance differentiation of osteoblasts, that EP2A is a true selective agonist for this receptor and that PGE(2) has an additional anabolic effect likely mediated by the EP4 receptor.

Effects of prostaglandin E2 and lipopolysaccharide on osteoclastogenesis in RAW 264.7 cells

INTRODUCTION

Prostaglandins (PGs) can act on both hematopoietic and osteoblastic lineages to enhance osteoclast formation.

METHODS

We examined PGE2 stimulated osteoclastogenesis in RAW 264.7 cells and the role of endogenous PGE2 in lipopolysaccharide (LPS) stimulated osteoclastogenesis.

RESULTS

RANKL (1-100 ng/ml) increased formation of osteoclasts, defined as tartrate resistant acid phosphatase multinucleated cells, with peak effects at 30 ng/ml. Addition of PGE2 (0.01-1.0 microM) to RANKL (30 ng/ml) dose dependently increased osteoclast number 30-150%. Use of NS-398 (0.1 microM) or indomethacin (Indo, 1.0 micro M) to block endogenous PG synthesis had little effect on the response to RANKL alone but significantly decreased the response to PGE2. Addition of LPS (100 ng/ml) to RANKL increased osteoclast number 50%, and this response was significantly decreased by NS-398 and Indo. RANKL and PGE2 produced small, additive increases in COX-2 mRNA levels, while LPS produced a larger increase. PG release into the medium was not increased by RANKL and PGE2 but markedly increased by LPS.

CONCLUSION

We conclude that RANKL stimulated osteoclastogenesis can be enhanced by PGE2 and LPS though direct effects on the hematopoietic cell lineage and that these effects may be mediated in part by induction of COX-2 and enhanced intracellular PG production.

Null mutation for macrophage migration inhibitory factor (MIF) is associated with less aggressive bladder cancer in mice

Background

Inflammatory cytokines may promote tumorigenesis. Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine with regulatory properties over tumor suppressor proteins involved in bladder cancer. We studied the development of bladder cancer in wild type (WT) and MIF knockout (KO) mice given N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN), a known carcinogen, to determine the role of MIF in bladder cancer initiation and progression.

Methods

5-month old male C57Bl/6 MIF WT and KO mice were treated with and without BBN. Animals were sacrificed at intervals up to 23 weeks of treatment. Bladder tumor stage and grade were evaluated by H&E. Immunohistochemical (IHC) analysis was performed for MIF and platelet/endothelial cell adhesion molecule 1 (PECAM-1), a measure of vascularization. MIF mRNA was analyzed by quantitative real-time polymerase chain reaction.

Results

Poorly differentiated carcinoma developed in all BBN treated mice by week 20. MIF WT animals developed T2 disease, while KO animals developed only T1 disease. MIF IHC revealed predominantly urothelial cytoplasmic staining in the WT control animals and a shift toward nuclear staining in WT BBN treated animals. MIF mRNA levels were 3-fold higher in BBN treated animals relative to controls when invasive cancer was present. PECAM-1 staining revealed significantly more stromal vessels in the tumors in WT animals when compared to KOs.

Conclusion

Muscle invasive bladder cancer with increased stromal vascularity was associated with increased MIF mRNA levels and nuclear redistribution. Consistently lower stage tumors were seen in MIF KO compared to WT mice. These data suggest that MIF may play a role in the progression to invasive bladder cancer.

Cyclooxygenase-2 gene disruption promotes proliferation of murine calvarial osteoblasts in vitro

Cyclooxygenase-2 (COX-2) is highly expressed in osteoblasts, and COX-2 produced prostaglandins (PGs) can increase osteoblastic differentiation in vitro. The goal of this study was to examine effects of COX-2 expression on calvarial osteoblastic proliferation and apoptosis. Primary osteoblasts (POBs) were cultured from calvariae of COX-2 wild-type (WT) and knockout (KO) mice. POB proliferation was evaluated by (3)H-thymidine incorporation and analysis of cell replication and cell cycle distribution by flow cytometry. POB apoptosis was evaluated by annexin and PI staining on flow cytometry. As expected, PGE(2) production and alkaline phosphatase (ALP) activity were increased in WT cultures compared to KO cultures. In contrast, cell numbers were decreased in WT compared to KO cells by day 4 of culture. Proliferation, measured on days 3-7 of culture, was 2-fold greater in KO than in WT POBs and associated with decreased Go/G1 and increased S cell cycle distribution. There was no significant effect of COX-2 genotype on apoptosis under basal culture conditions on day 5 of culture. Cell growth was decreased in KO POBs by the addition of PGE(2) or a protein kinase A agonist and increased in WT POBs by the addition of NS398, a selective COX-2 inhibitor. In contrast, differentiation and cell growth in marrow stromal cell (MSC) cultures, evaluated by ALP and crystal violet staining respectively, were increased in MSCs from WT mice compared to MSCs from KO mice, and exogenous PGE(2) increased cell growth in KO MSC cultures. We conclude that PGs secondary to COX-2 expression decrease osteoblastic proliferation in cultured calvarial cells but increase growth of osteoblastic precursors in MSC cultures.

Strontium ranelate promotes osteoblastic differentiation and mineralization of murine bone marrow stromal cells: involvement of prostaglandins

Strontium ranelate is a new anti-osteoporosis treatment. This study showed that strontium ranelate stimulated PGE(2) production and osteoblastic differentiation in murine marrow stromal cells, which was markedly reduced by inhibition of COX-2 activity or disruption of COX-2 gene expression. Hence, some anabolic effects of strontium ranelate may be mediated by the induction of COX-2 and PGE(2) production.

INTRODUCTION

Strontium ranelate is an orally active drug that reduces vertebral and hip fracture risk by increasing bone formation and reducing bone resorption. Strontium ranelate effects on bone formation are the result of increased osteoblastic differentiation and activity, but the mechanisms governing these effects are unknown. Based on previous work, we hypothesized that strontium ranelate increases cyclooxygenase (COX)-2 expression and that, consequently, the prostaglandin E(2) (PGE(2)) produced could mediate some effects of strontium ranelate on osteoblasts.

MATERIALS AND METHODS

Marrow stromal cells (MSCs) from COX-2 wildtype (WT) and knockout (KO) mice were cultured with and without low-dose dexamethasone. Osteoblastic differentiation was characterized by alkaline phosphatase (ALP) activity, real-time PCR for ALP and osteocalcin (OCN) mRNA expression, and alizarin red staining for mineralization. Medium PGE(2) was measured by radioimmunoassay or enzyme immunoassay.

RESULTS AND CONCLUSIONS

In MSCs from COX-2 WT mice, strontium ranelate significantly increased ALP activity, ALP and OCN mRNA expression, and mineralization after 14 or 21 days of culture. A short treatment at the beginning of the culture (0-7 days) with strontium ranelate was as effective as continuous treatment. Strontium ranelate (1 and 3 mM Sr(+2)) dose-dependently increased PGE(2) production, with maximum PGE(2) production occurring during the first week of culture. NS-398, a selective COX-2 inhibitor, blocked the strontium ranelate stimulation of PGE(2) production and significantly inhibited the strontium ranelate stimulation of ALP activity. In MSCs from COX-2 KO mice, the strontium ranelate stimulation of ALP and OCN mRNA expression and mineralization were markedly reduced compared with COX-2 WT cultures. Similar effects of strontium ranelate on osteoblastic markers and on PGE(2) production were seen when MSCs were cultured with or without low-dose dexamethasone (10 nM). We conclude that PGE(2) produced by the strontium ranelate induction of COX-2 expression plays a role in strontium ranelate-induced osteoblastic differentiation in MSCs in vitro.

Null mutation in macrophage migration inhibitory factor prevents muscle cell loss and fibrosis in partial bladder outlet obstruction

Idiopathic detrusor underactivity (DU) and detrusor decompensation which develops following partial bladder outlet obstruction (pBOO) are both associated with smooth muscle degeneration and fibrosis. Macrophage migration inhibitory factor (MIF), an important mediator of bladder inflammation, has been shown to promote fibroblast survival and muscle death in other tissues. We evaluated the hypothesis that MIF has similar actions in the bladder by studying detrusor responses to pBOO or sham surgery in anesthetized female mice rendered null for the mif gene (MIF KO) and in wild-type (WT) controls, all killed 3 wk after surgery. WT mice revealed intense MIF immunoreactivity in urothelial cells which decreased, without change in overall mif mRNA levels. Stereologically sound quantitative morphometric measurements were performed in the middetrusor region of each bladder. MIF KO bladders were normal in appearance, yet were 30–40% heavier, with increased middetrusor collagen and muscle, compared with WT controls. In WT mice, pBOO increased the collagen-to-muscle ratio 1.9-fold and middetrusor collagen 1.8-fold, while nucleated muscle counts were 22% lower. In MIF KO mice, by contrast, pBOO had no significant effect on any of these parameters. In primary bladder muscle cultures, treatment with rMIF protein increased TUNEL staining, raising the proportion of early and late apoptotic cells on flow cytometry. Our studies implicate MIF in the sequence of events leading to detrusor muscle loss and fibrosis in obstruction. They raise the possibility that strategies designed to antagonize MIF synthesis, release, or biological activity could prevent or delay DU and urinary retention.

Fluid flow induces Rankl expression in primary murine calvarial osteoblasts

Mechanical loading of bone generates fluid flow within the mineralized matrix that exerts fluid shear stress (FSS) on cells. We examined effects of FSS on receptor activator of nuclear factor kappa B ligand (RANKL), a critical factor for osteoclast formation. Primary murine osteoblasts were subjected to pulsatile FSS (5 Hz, 10 dynes/cm(2)) for 1 h and then returned to static culture for varying times (post-FSS). Protein levels were measured by Western analysis and mRNA by Northern analysis, RT-PCR and quantitative PCR. There were 20- to 40-fold increases in RANKL mRNA at 2-4 h post-FSS. RANKL protein was induced by 2 h post-FSS and remained elevated for at least 8 h. Effects were independent of cyclooxygenase-2 activity. Small increases (up to three-fold) in mRNA of the decoy receptor for RANKL, osteoprotegerin, were seen. Five min of FSS, followed by static culture, was as effective in stimulating RANKL mRNA as 4 h of continuous FSS. FSS induced cAMP activity, and H-89, a protein kinase A (PKA) inhibitor, blocked the FSS induction of RANKL. H-89 also inhibited the PKC pathway, but specific PKC inhibitors, GF109203X and Go6983, did not inhibit FSS-induced RANKL. FSS induced phosphorylation of ERK1/2, and PD98059, an inhibitor of the ERK pathway, inhibited the FSS induction of RANKL mRNA 60%-90%. Thus, brief exposure to FSS resulted in sustained induction of RANKL expression after stopping FSS, and this induction was dependent on PKA and ERK signaling pathways. Increased RANKL after mechanical loading may play a role in initiating bone remodeling.

Overexpression of Cox-2 in Human Osteosarcoma Cells Decreases Proliferation and Increases Apoptosis

Overexpression of cyclooxygenase-2 (COX-2) is generally considered to promote tumorigenesis. To investigate a potential role of COX-2 in osteosarcoma, we overexpressed COX-2 in human osteosarcoma cells. Saos-2 cells deficient in COX-2 expression were retrovirally transduced or stably transfected with murine COX-2 cDNA. Functional expression of COX-2 was confirmed by Northern and Western analyses and prostaglandin production. Overexpression of COX-2 reduced cell numbers by 50% to 70% compared with controls. Decreased proliferation in COX-2-overexpressing cells was associated with cell cycle prolongation in G(2)-M. Apoptosis, measured by both Annexin V binding assay and terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling staining, was increased in cells overexpressing COX-2, and the increase was not reversed by treatment with NS-398, indicating that the effects were not mediated by prostaglandins. Retroviral COX-2 overexpression in two other human osteosarcoma cell lines, U2OS and TE85, also decreased cell viability. However, in the human colon carcinoma HCT-116 cell line, which is deficient in COX-2, retroviral overexpression of COX-2, at similar efficiency as in Saos-2 cells, increased resistance to apoptosis. Reactive oxygen species (ROS), measured by flow cytometry, were increased by COX-2 overexpression in Saos-2 cells but not in HCT-116 cells. Inhibition of peroxidase activity, but not of COX activity, blocked the ROS increase. Antioxidants blocked the increase in ROS and the increase in apoptosis due to COX-2 overexpression in Saos-2 cells. Our results suggest that (a) COX-2 overexpression in osteosarcoma cells may increase resistance to tumorigenesis by increasing ROS to levels that decrease cell viability and (b) the effects of COX-2 overexpression are cell type/tissue dependent.

Role of Cbfa1/Runx2 in the fluid shear stress induction of COX-2 in osteoblasts

Induction of cyclooxygenase-2 (COX-2) is thought to be important for the anabolic effects of mechanical loading. The transcription factor Cbfa1/Runx2 is essential for osteoblastic differentiation. We examined the role of Cbfa1 in the fluid shear stress (FSS) induction of COX-2 in MC3T3-E1 cells stably transfected with a COX-2 promoter-luciferase reporter. Cells were subjected to FSS for 30 min and returned to static culture (post-FSS). COX-2 mRNA and promoter activity peaked 0.5-1h and 2-3h, respectively, post-FSS. Mutation of the Cbfa1 consensus sequence at -267/-261 bp decreased the FSS fold-induction of luciferase activity by 50%. On electrophoretic mobility shift assay (EMSA), proteins binding to an oligonucleotide spanning the Cbfa1 site were supershifted by specific antibody to Cbfa1. FSS did not increase Cbfa1 binding on EMSA or Cbfa1 mRNA or protein levels. These data suggest that transcriptional activity of Cbfa1, independent of its level of expression, is necessary for maximal FSS induction of COX-2 in osteoblasts.

Differential regulation of platelet-derived growth factor stimulated migration and proliferation in osteoblastic cells

Osteoblastic migration and proliferation in response to growth factors are essential for skeletal development, bone remodeling, and fracture repair, as well as pathologic processes, such as metastasis. We studied migration in response to platelet-derived growth factor (PDGF, 10 ng/ml) in a wounding model. PDGF stimulated a twofold increase in migration of osteoblastic MC3T3-E1 cells and murine calvarial osteoblasts over 24-48 h. PDGF also stimulated a tenfold increase in 3H-thymidine (3H-TdR) incorporation in MC3T3-E1 cells. Migration and DNA replication, as measured by BrdU incorporation, could be stimulated in the same cell. Blocking DNA replication with aphidicolin did not reduce the distance migrated. To examine the role of mitogen-activated protein (MAP) kinases in migration and proliferation, we used specific inhibitors of p38 MAP kinase, extracellular signal regulated kinase (ERK), and c-Jun N-terminal kinase (JNK). For these signaling studies, proliferation was measured by carboxyfluorescein diacetate succinimidyl ester (CFSE) using flow cytometry. Inhibition of the p38 MAP kinase pathway by SB203580 and SB202190 blocked PDGF-stimulated migration but had no effect on proliferation. Inhibition of the ERK pathway by PD98059 and U0126 inhibited proliferation but did not inhibit migration. Inhibition of JNK activity by SP600125 inhibited both migration and proliferation. Hence, the stimulation of migration and proliferation by PDGF occurred by both overlapping and independent pathways. The JNK pathway was involved in both migration and proliferation, whereas the p38 pathway was predominantly involved in migration and the ERK pathway predominantly involved in proliferation.

Do cyclooxygenase-2 knockout mice have primary hyperparathyroidism?

The absence of cyclooxygenase-2 (COX-2) activity in vitro reduces differentiation of both bone-forming and bone-resorbing cells. To examine the balance of COX-2 effects on bone in vivo, we studied COX-2 knockout (KO) and wild-type (WT) mice. After weaning, KO mice died 4 times faster than WT mice, consistent with reports of progressive renal failure in KO mice. Among KO mice killed at 4 months of age, some had renal failure with marked secondary hyperparathyroidism, but others appeared healthy. On the assumption that renal failure was not inevitable in COX-2 KO mice and that phenotypic differences might increase with age, we studied KO mice surviving to 10 months of age with serum creatinine levels similar to those of WT mice. In 10-month-old male KO mice, serum calcium and PTH, but not phosphorus, levels were increased compared with those in WT mice. 1,25-Dihydroxyvitamin D(3) levels were markedly elevated in KO mice. Skeletal analysis showed small nonsignificant decreases in cortical bone density by BMD and either an increase (distal femur, by microcomputed tomography) or no difference (distal femur, by static histomorphometry) in trabecular bone density in KO mice. There was a trend toward increased percent osteoblastic and osteoclastic surfaces, and on dynamic histomorphometry, the rates of trabecular bone formation and mineral apposition were increased in KO mice relative to WT mice. Similar trends were observed for most parameters in 10-month-old female COX-2 KO mice. However, rates of trabecular bone formation and mineral apposition were increased in 10-month-old WT females compared with males and did not increase further in female KO mice. These data suggest that COX-2 KO mice with intact renal function have primary hyperparathyroidism, and that effects of increased PTH and 1,25-dihydroxyvitamin D(3) to increase bone turnover may compensate for the absence of COX-2.

Role of cyclooxygenase-2 in bone resorption

Prostaglandins (PGs) are abundant in bone and are potent regulators of bone cell function. Osteoblasts produce PGs, and this production is highly regulated by local and systemic factors. Bone resorption is a highly regulated process involving interactions of osteoclastic precursors with osteoblasts or stromal cells. Many factors that stimulate PGs production also stimulate resorption in organ and marrow culture. Cyclooxygenase (COX) is the rate-limiting enzyme in the conversion of arachidonic acid to PGs. There are two forms of COX, COX-1 and COX-2. COX-2 is an inducible primary-response or immediate early gene. COX-2 expression is induced by many factors through the transcriptional pathway in osteoblasts. Stimulated production of PGs by osteoblasts requires both the induction of COX-2 expression and the availability of arachidonic acid substrate. PGs are complex, potent regulators of bone cell function in vivo. PGE2, which may be the most important local eicosanoid in skeletal regulation, can stimulate resorption. We report that COX-2 expression and associated PG production are necessary for maximal resorption responses to 1,25 (OH)2D3 and parathyroid hormone (PTH). PGs can increase osteoclast formation by enhancing induction of the receptor activator of nuclear factor-kappa B ligand (RANKL) expression in osteoblasts and enhancing the action of RANKL on osteoclast precursors by inhibiting granulocyte macropharge-colony stimulating factor (GM-CSF). In vitro, PGE2 can stimulate the differentiation of both osteoblasts and osteoclasts, and the net balance of these two effects under physiologic or pathologic conditions in vivo is not yet clear. Our in vivo data suggest that a role for COX-2 in bone resorption may be most evident when bone resorption is accelerated. Some of the complexity of PG actions on bone can be explained by the multiplicity of receptors for PGs. There are at least four distinct receptors for PGE2 with differential signaling pathways that have not yet been fully elucidated. Further studies are needed to clarify the specific pathways of PGs action in bone. Once this is accomplished, it may be possible to identify therapeutic applications of manipulating PGs in skeletal disorders.

Fluid flow induces COX-2 expression in MC3T3-E1 osteoblasts via a PKA signaling pathway

Mechanical loading of bone generates fluid flow within the mineralized matrix which can exert fluid shear stress (FSS) at cell membranes. FSS induces new transcription of cyclooxygenase-2 (COX-2) in MC3T3-E1 osteoblasts, with peak effects at 4-5h. Using MC3T3-E1 cells stably transfected with the COX-2 promoter fused to a luciferase reporter, we examined involvement of the protein kinase A (PKA) and protein kinase C (PKC) signaling pathways in the peak COX-2 mRNA and luciferase responses to FSS (10dyn/cm(2)). Neither inhibition nor down-regulation of the PKC pathway affected the FSS stimulation of COX-2 mRNA or luciferase activity. In contrast, inhibitors of the PKA pathway, used at doses which inhibited forskolin-stimulated luciferase activity by 70-80%, reduced FSS-stimulated COX-2 mRNA expression and luciferase activity by 50-80%. Hence, peak FSS induction of COX-2 expression in MC3T3-E1 osteoblastic cells is largely dependent on the PKA signaling pathway.

Cell-to-Cell adhesion via intercellular adhesion molecule-1 and leukocyte function-associated antigen-1 pathway is involved in 1alpha,25(OH)2D3, PTH and IL-1alpha-induced osteoclast differentiation and bone resorption

Cell-to-cell interaction is required for the differentiation of osteoclast precursors as well as for osteoclast function. The present study was undertaken to determine whether 1,25 dihydroxyvitamin D3 (1,25D), PTH, IL-1alpha and PGE2 depend on cell-to-cell interactions through the intercellular adhesion molecule (ICAM)-1/leukocyte function-associated antigen (LFA)-1 pathway in osteoclast formation and bone resorption. We found that mouse osteoblasts expressed ICAM-1 and that the expression was increased by treatment with PTH, IL-1alpha or 1,25D, but not by PGE2. In resorption assays measuring either 45Ca release from bone organ cultures or pit formation in bone cell cultures, 1,25D-, PTH- and IL-1alpha-stimulated resorption was inhibited by anti-ICAM-1 monoclonal antibody (mAb) and/or anti-LFA-1 mAb, while basal and PGE2-stimulated bone resorbing activities were not affected by these mAbs. Furthermore, in a mouse bone marrow culture system, stimulation of osteoclast-like (OCL) cell formation by 1,25D (10 nM), PTH (10 ng/ml) or IL-1alpha (10 ng/ml) was inhibited by the addition of anti-ICAM-1 mAb and/or anti-LFA-1 mAb. In a coculture system of murine spleen cells and osteoblasts, the ICAM-1/LFA-1 interaction was also involved in 1,25D-, PTH- and IL-1alpha-stimulated TRAP-positive MNC formation. However, anti-ICAM-1 mAb and anti-LFA-1 mAb did not alter either 1,25D- or PTH-stimulated receptor activator of NF-kappaB ligand (RANKL) mRNA transcription in bone marrow cultures. Taken together, we here propose that ICAM-1-mediated cell-to-cell adhesion of osteoblasts and osteoclast precursors is involved in RANKL-dependent osteoclast maturation stimulated by 1,25D, PTH, and IL-1alpha.

Regulation of fibroblast growth factor 2 and fibroblast growth factor receptors by transforming growth factor beta in human osteoblastic MG-63 cells

Fibroblast growth factor 2 (FGF-2) and its receptors (FGFRs) are important regulators of bone cell function. Although FGF-2 is a major modulator of bone cell function, its expression and regulation in human osteoblasts have not been investigated. We examined FGF-2 messenger RNA (mRNA) expression and regulation in the human osteosarcoma MG-63 cells. Northern analysis revealed that MG-63 cells expressed FGF-2 mRNA transcripts of 7, 4, 2.2, and 1.3 kilobases (kb). In the absence of serum, treatment with transforming growth factor beta (TGF-beta; 0.1-10 ng/ml) increased all FGF-2 mRNA transcripts. Maximal increase was seen with 1 ng/ml of TGF-beta. TGF-beta increased FGF-2 mRNA expression within 2 h and this was sustained for 24 h. Phorbal myristate acetate (PMA; 1 microM) also increased FGF-2 mRNA at 6 h. Time course studies showed that TGF-beta did not significantly alter FGFR1 or FGFR2 mRNA expression in MG-63 cells. Western blotting with anti-human FGF-2 revealed that MG-63 cells synthesize three isoforms of FGF-2 protein of approximately 18, 22/23, and 24 kDa, which were increased after either 6 h or 24 h of treatment with TGF-beta. Increased FGF-2 mRNA and protein expression in response to TGF-beta was markedly reduced by the protein kinase A (PKA) inhibitor H-89. Immunogold labeling of MG-63 cells treated with TGF-beta showed increased labeling for FGF-2 and FGFR2 in the nuclei. In contrast, TGF-beta treatment significantly decreased FGFR1 labeling in the nuclei. These data show that TGF-beta regulates FGF-2 gene expression in human osteosarcoma cells. Furthermore, TGF-beta modulates the cellular localization of FGF-2 and its receptors.

Identification of multiple cis-acting elements mediating the induction of prostaglandin G/H synthase-2 by phorbol ester in murine osteoblastic cells

The tumor promoter phorbol 13-myristate 12-acetate (PMA), the best characterized protein kinase C agonist, frequently regulates gene expression via activation of Fos/Jun (AP-1) complexes. PMA rapidly and transiently induces prostaglandin G/H synthase-2 (PGHS-2) expression in murine osteoblastic MC3T3-E1 cells, but no functional AP-1 binding motifs in the 5'-flanking region have been identified. In MC3T3-E1 cells transfected with -371/+70 bp of the PGHS-2 gene fused to a luciferase reporter gene (Pluc), PMA stimulates luciferase activity up to eightfold. Computer analysis of the sequence of the PGHS-2 promoter region identified three potential AP-1 elements in the -371/+70 bp region, and deletion analysis suggested that the sequence 5'-aGAGTCA-3' at -69/-63 bp was most likely to mediate stimulation by PMA. Mutation of the putative AP-1 sequence reduces the ability of PMA to stimulate Pluc activity by 65%. On electrophoretic mobility shift analysis (EMSA), PMA induces binding to a PGHS-2 probe spanning this sequence, binding is blocked by an unlabeled AP-1 canonical sequence, and antibodies specific for c-Jun and c-Fos inhibit binding. Mutation of this AP-1 site also causes a small (22%) but significant reduction in the serum stimulation of Pluc activity in transiently transfected MC3T3-E1 cells. On EMSA, serum induces binding to a PGHS-2 probe spanning the AP-1 site, binding is blocked by an unlabeled AP-1 canonical sequence, and antibodies specific for c-Jun and c-Fos inhibit binding. Joint mutation of this AP-1 site and the nearby CRE site at -56/-52 bp, previously shown to mediate serum, v-src and PDGF induction of PGHS-2 in NIH-3T3 cells, blocks both PMA and serum induction of Pluc activity in MC3T3-E1 cells. Hence, the AP-1 and CRE binding sites are jointly but differentially involved in both the PMA and serum stimulation of PGHS-2 promoter activity.

Transforming growth factor-beta1 regulation of prostaglandin G/H synthase-2 expression in osteoblastic MC3T3-E1 cells

Transforming growth factor-beta (TGFbeta) plays an important role in bone development and remodeling. TGFbeta stimulates PGE2 production, enhances interleukin-1-stimulated PGE2 production, and can stimulate PG-mediated bone resorption. We found that TGFbeta induced prostaglandin G/H synthase (PGHS-2) messenger RNA (mRNA) and PGE2 production in neonatal mouse calvarial cultures and in primary cells derived from these calvariae. We used MC3T3-E1 cells, an immortalized osteoblastic cell line derived from mouse calvariae, to examine the mechanism of PGHS-2 induction. PGHS-2 mRNA was rapidly induced by TGFbeta (10 ng/ml) in MC3T3-E1 cells; mRNA levels peaked at 4-8 h and were still elevated at 24 h. Induction of PGHS-2 protein and PGE2 production correlated with PGHS-2 mRNA levels. In contrast, TGFbeta had much less effect on PGHS-1 mRNA levels. Unlike the response to other agonists, PGHS-2 mRNA induction by TGFbeta was not enhanced by cycloheximide pretreatment, suggesting a requirement for new protein synthesis. To study transcriptional regulation, cells were stably transfected with a PGHS-2 promoter-luciferase reporter construct containing 371 bp of the 5'-flanking region and 70 bp of untranslated DNA from the PGHS-2 gene. TGFbeta-stimulated luciferase activity paralleled PGHS-2 mRNA induction. Stimulation of luciferase activity and PGHS-2 mRNA levels by other agonists, including interleukin-1, TGF alpha, forskolin, and phorbol 13-myristate 12-acetate, were enhanced by TGFbeta. A 90% drop in luciferase activity occurred with deletion of the region from -371 to -213 bp of the PGHS-2 promoter. The PG response to TGFbeta in MC3T3-E1 cells appears to be mediated primarily by transcriptional regulation of PGHS-2 expression through one or more cis-acting elements located between -371 and -213 bp in the 5'-flanking region of the PGHS-2 gene.

Stimulation of prostaglandin E2 production by interleukin-1 alpha and transforming growth factor alpha in osteoblastic MC3T3-E1 cells

The mechanism by which interleukin-1 (IL-1) and transforming growth factor alpha (TGF-alpha) regulate prostaglandin synthesis has been examined in the clonal mouse osteoblastic cell line MC3T3-E1. Cells were grown in DMEM containing 10% fetal calf serum. Prostaglandin E2 (PGE2) production was determined by radioimmunoassay or by prelabeling cells with [3H]arachidonic acid, followed by high-performance liquid chromatography (HPLC) analysis of the labeled products released into the medium. Prostaglandin G/H synthase (PGHS) mRNAs were quantified by northern blot analysis using [32P]labeled cDNA probes. By HPLC, PGE2 was the major prostanoid produced under basal or stimulated conditions. No release of thromboxane or 6-keto-PGF1 alpha into the medium was detected. PGE2 production was stimulated approximately 7- to 14-fold by IL-1 (1 ng/ml) and 3- to 8-fold by TGF-alpha (30 ng/ml) after 24 h. In combination, however, IL-1 and TGF-alpha caused a synergistic 37- to 71-fold increase in PGE2 accumulation. PGHS-1 mRNA levels were maximally increased approximately 2- to 3-fold by IL-1 and 1.5 to 2.5-fold by TGF-alpha after 24 h; the combination of IL-1 and TGF-alpha produced only an additive 3- to 6-fold increase. Western blotting revealed a corresponding 3-fold increase in immunoreactive PGHS-1 protein in response to combined IL-1 and TGF-alpha. PGHS-2 mRNA was increased 1.4-fold by TGF-alpha at 1 h, and the combination of IL-1 and TGF-alpha caused a 1.7-fold increase.(ABSTRACT TRUNCATED AT 250 WORDS)

An evaluation of the relative contributions of exposure to sunlight and of diet to the circulating concentrations of 25-hydroxyvitamin D in an elderly nursing home population in Boston

We investigated the vitamin D status of a Caucasian elderly population in a long-term-care facility in Boston. Comparison was made with a group of free-living elderly people. The sunlight exposure of residents was monitored and its effect on the serum concentrations of 25-hydroxyvitamin D [25(OH)D] was compared with contributions from diet and multivitamins. Seasonal changes in serum 25(OH)D concentrations caused by sunlight exposure were greatest in the free-living subjects and declined in magnitude as the mobility of the volunteers decreased. Diet failed to provide an adequate amount of vitamin D for volunteers who had minimal outdoor activity. Use of a multivitamin supplement containing 10 micrograms (400 IU) vitamin D maintained serum 25(OH)D concentrations greater than 37.5 nmol/L.