Abstract P5-05-01: Metabolic enzyme PFKFB4 activates transcriptional coactivator SRC-3 to drive aggressive metastatic breast cancer

Background: Metabolic rewiring is one of the central hallmarks of cancer progression and survival to support anabolic and energetic demands. Tumor cells constantly alter their metabolic state in response to oncogenic stimuli, nutrient availability, and interaction with immune cells however the precise regulation that precedes the metabolic alteration is poorly understood. Here we report a direct interaction of glycolytic enzyme PFKFB4 with transcriptional coregulator SRC-3. PFKFB4 functions as a critical regulator of Warburg effect and our study reveals that upon glucose stimulation PFKFB4 activates SRC-3 driving an invasive-metastatic breast cancer.

Methods: Molecular experiments were performed to understand the transcriptional activation of SRC-3 by PFKFB4 enzyme. Chromatin immunoprecipitation and gene expression studies were performed to investigate the functions of PFKFB4/SRC-3 crosstalk on transcriptional regulation. Metabolomics and isotope tracing studies were performed to identify the metabolic adaptations regulated by PFKFB4/SRC-3 in breast tumors. PFKFB4-knockout was established using CRISPR-Cas9 system and functional studies were carried out to define its role in tumor cell proliferation, invasion-migration, and breast to lung metastasis. Human breast tumor samples were evaluated to identify the clinical importance of PFKFB4/SRC-3 crosstalk in patients.

Results:Molecular studies revealed that PFKFB4 enzyme phosphorylates SRC-3 at serine 857 (S857) enhancing its transcriptional activity, whereas either suppression of PFKFB4 or ectopic expression of a phosphorylation-deficient SRC-3 mutant S857A (SRC-3S857A) significantly abolished SRC-3-mediated transcriptional output (p<0.000001). Functionally, PFKFB4-driven SRC-3 activation drives glucose flux towards the pentose phosphate pathway enabling purine synthesis by transcriptionally upregulating the expression of enzyme transketolase (TKT). Deletion of PFKFB4 by CRISPR-Cas9 system resulted in significantly reduced proliferation (p<0.05) and migration-invasion (p<0.001) compared to wildtype breast tumor cells. Ablation of SRC-3 or PFKFB4 suppressed in vivo breast tumor growth and prevents metastasis to the lung from an orthotopic setting (p<0.0001). PFKFB4 and phosphorylated SRC-3 levels are significantly increased in breast tumors (p=0.02), whereas, in patients with the basal subtype, PFKFB4 and SRC-3 drive a common protein signature that correlates with the poor survival of TNBC patients (p=0.03).

Conclusion:Our data suggest that the Warburg pathway enzyme PFKFB4 acts as a molecular fulcrum that couples sugar metabolism to transcriptional activation by stimulating SRC-3 to promote aggressive metastatic tumors. It also provides first evidence how Warburg pathway drives aggressive breast tumorigenesis by directly activating powerful oncogene SRC-3. Our work suggests that targeting the PFKFB4–SRC-3 axis may be therapeutically valuable in breast tumors that are notably dependent on glucose metabolism.

(This work is funded by grants from Susan G. Komen and NCI to S.D.)

Citation Format: Dasgupta S, Anand V, John H, Sawant Dessai A, Katsuta E, Takabe K, O'Malley B. Metabolic enzyme PFKFB4 activates transcriptional coactivator SRC-3 to drive aggressive metastatic breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-05-01.

Abstract P4-08-09: Targeting Thyroid Receptor b in Estrogen Receptor Negative Breast Cancer

Background: The treatment of estrogen receptor (ER)-negative breast cancer (BC) is a major clinical problem due to the lack of useful therapeutic targets. Nuclear receptors (NRs) are potential targets in these patients because they regulate global transcriptional events and many already have agonists/antagonists available.

Material and Methods: We used microarray analysis of 227 ER-negative tumors to identify NR targets, and performed hierarchical clustering using 41 NRs. Expressed receptors were scored using prediction analysis of microarrays (PAM) across clustered groups. Cell lines were matched to subtypes using previously described data (Neve et al. 2006). Candidate gene expression levels were confirmed by qRT-PCR using TaqMan probes. pGIPZ lentiviral vectors encoding shRNA were used to knockdownselected candidates. MTT and soft agar assays were used to measure chemosensitivity and growth following treatment with Docetaxel (Doc), Doxorubicin (Dox), or Cisplatin (Cis). Statistical analysis was performed using Red-R.

Results: The 41 NRs clustered tumors into 5 groups. For each group we selected genes representing the highest ranked discriminators, and examined their effects in cell lines matching each groups' gene signature. Thyroid hormone receptor b (THRβ) was selected from group V. The expression levels of this receptor were confirmed by qRT-PCR and Western blot analysis.

Knockdown of THRβ in ER-negative HCC2185 cells rendered cells more resistant to all chemotherapeutics by using MTT assay. Similar results were confirmed in ER-negative MDA-MB-453 and HCC202 cells. Knockdown of THRβ enhanced colony forming potential in anchorage-independent soft agar assays in MDA-MB-453 and HCC202 cells. Statistical analysis using clinical data from Sabatier et al. (BCRT 2011) showed that patients with low THRb have a worse clinical outcome. In order to translate these findings into the clinic, we treated cells with a specific THRβ agonists, GC-1 and KB-141. GC-1 inhibited cell growth in growth assays, and synergistic effects were observed when cells were treated with GC-1 and Docetaxel in combination. Re-expression of ERα protein was observed in ER-nagative cells lines after treatment with GC-1 and KB141, suggesting that modulation of THRβ may also extend hormonal therapy to this hormonally insensitive group of patients.

Conclusion: Clinical targeting of NRs in ER-negative BCs is a novel strategy since receptors can be specifically targeted with ligands. Our data suggest that chemotherapy response in ER-negative patients overexpressing THRβ could be enhanced with a THRβ agonist. Similarly, functional re-activation of ERα by activating THRβ might extend hormonal therapies to these patients as well.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-08-09.

Use of e-learning to enhance medical students' understanding and knowledge of healthcare-associated infection prevention and control

An online infection prevention and control programme for medical students was developed and assessed. There was a statistically significant improvement (P<0.0001) in the knowledge base among 517 students after completing two modules. The majority of students who completed the evaluation were positive about the learning experience.

A Single Nucleotide Polymorphism in Steroid Receptor Coactivator-1 Diminishes the Coactivation of ERα

Estrogen signaling is critical in the progression of a large fraction of breast cancers as well as in the maintenance of bone mineral density. Generally speaking, Tamoxifen, a selective estrogen receptor modulator (SERM), blocks estrogen signaling in the breast by acting as an antagonist at the same time as promoting estrogen signaling in the bone by acting as an agonist. This tissue specific action characteristic of SERMs is thought to be maintained by the balance of levels and/or activities of estrogen receptor (ER) coregulators. Because of this critical role, single nucleotide polymorphisms (SNPs) in ER coregulators could have a dramatic effect on tamoxifen action.Previous studies have implicated steroid receptor coactivator-1 (SRC-1) as a critical coregulator for the mixed antagonist-agonist specificity of tamoxifen. By using an ERE-Tk-Luciferase transient transfection assay, we have shown that a SNP causing the amino acid change P1272S in SRC-1 dramatically reduces its ability to coactivate ERα.To assess the impact of this SNP on tamoxifen action in breast cancer we decided to genotype the SRC-1 P1272S SNP in a breast tumor DNA bank. This bank was generated from archived tumors from individuals either exclusively receiving adjuvant tamoxifen or not receiving any adjuvant therapy following surgical resection. Currently, the bank is composed of 1000 samples divided equally among the two groups. Genotyping for the SRC-1 P1272S SNP is currently underway.Since SRC-1 has also been shown to be important in proper maintenance of bone mineral density (BMD) and in the agonist action of tamoxifen in certain tissues, we also assessed the impact of the P1272S SNP in bone following tamoxifen therapy. We genotyped breast cancer patients exclusively receiving tamoxifen therapy (i.e. no chemotherapy, no radiation) who had lumbar (n=113) and/or hip (n=108) BMD scans before and after 12 months of tamoxifen therapy. We observed a significant association between the SNP and bone loss; women harboring the P1272S SNP lost 6.4% of their lumbar BMD, while women with the WT version lost only 1.3% of their lumbar BMD.These findings illustrate the critical role of SRC-1 in tamoxifen action in bone, and potentially other hormone responsive tissues. Studies are ongoing to decipher the mechanism for decreased coactivation activity of the SNP, and also to extend the clinical association studies.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 66.

Mathematical model for low density lipoprotein (LDL) endocytosis by hepatocytes

Individuals with elevated levels of plasma low density lipoprotein (LDL) cholesterol (LDL-C) are considered to be at risk of developing coronary heart disease. LDL particles are removed from the blood by a process known as receptor-mediated endocytosis, which occurs mainly in the liver. A series of classical experiments delineated the major steps in the endocytotic process; apolipoprotein B-100 present on LDL particles binds to a specific receptor (LDL receptor, LDL-R) in specialized areas of the cell surface called clathrin-coated pits. The pit comprising the LDL-LDL-R complex is internalized forming a cytoplasmic endosome. Fusion of the endosome with a lysosome leads to degradation of the LDL into its constituent parts (that is, cholesterol, fatty acids, and amino acids), which are released for reuse by the cell, or are excreted. In this paper, we formulate a mathematical model of LDL endocytosis, consisting of a system of ordinary differential equations. We validate our model against existing in vitro experimental data, and we use it to explore differences in system behavior when a single bolus of extracellular LDL is supplied to cells, compared to when a continuous supply of LDL particles is available. Whereas the former situation is common to in vitro experimental systems, the latter better reflects the in vivo situation. We use asymptotic analysis and numerical simulations to study the longtime behavior of model solutions. The implications of model-derived insights for experimental design are discussed.

Mathematical modelling of competitive LDL/VLDL binding and uptake by hepatocytes

Elevated levels of low-density-lipoprotein cholesterol (LDL-C) in the plasma are a well-established risk factor for the development of coronary heart disease. Plasma LDL-C levels are in part determined by the rate at which LDL particles are removed from the bloodstream by hepatic uptake. The uptake of LDL by mammalian liver cells occurs mainly via receptor-mediated endocytosis, a process which entails the binding of these particles to specific receptors in specialised areas of the cell surface, the subsequent internalization of the receptor-lipoprotein complex, and ultimately the degradation and release of the ingested lipoproteins' constituent parts. We formulate a mathematical model to study the binding and internalization (endocytosis) of LDL and VLDL particles by hepatocytes in culture. The system of ordinary differential equations, which includes a cholesterol-dependent pit production term representing feedback regulation of surface receptors in response to intracellular cholesterol levels, is analysed using numerical simulations and steady-state analysis. Our numerical results show good agreement with in vitro experimental data describing LDL uptake by cultured hepatocytes following delivery of a single bolus of lipoprotein. Our model is adapted in order to reflect the in vivo situation, in which lipoproteins are continuously delivered to the hepatocyte. In this case, our model suggests that the competition between the LDL and VLDL particles for binding to the pits on the cell surface affects the intracellular cholesterol concentration. In particular, we predict that when there is continuous delivery of low levels of lipoproteins to the cell surface, more VLDL than LDL occupies the pit, since VLDL are better competitors for receptor binding. VLDL have a cholesterol content comparable to LDL particles; however, due to the larger size of VLDL, one pit-bound VLDL particle blocks binding of several LDLs, and there is a resultant drop in the intracellular cholesterol level. When there is continuous delivery of lipoprotein at high levels to the hepatocytes, VLDL particles still out-compete LDL particles for receptor binding, and consequently more VLDL than LDL particles occupy the pit. Although the maximum intracellular cholesterol level is similar for high and low levels of lipoprotein delivery, the maximum is reached more rapidly when the lipoprotein delivery rates are high. The implications of these results for the design of in vitro experiments is discussed.

Supporting evidence-based infection prevention and control practice in the National Health Service in England. The NHS/TVU/Intuition Approach

All successful strategies for preventing healthcare-associated infections require a multifaceted evidence-based approach that includes providing practitioners with the best evidence for clinically effective practice and then supporting them to understand and use this evidence to minimise infection risks and increase patient safety. This paper describes how national evidence-based guidelines from the Department of Health and the National Institute for Health and Clinical Excellence in England form the foundations for ensuring the availability of best evidence to practitioners, and how the development of an associated e-learning/blended learning programme is now supporting all NHS staff to effectively use this evidence to protect patients from the risk of preventable infections during care.

Topological characterization of crystallization of gold nanoclusters

In this study we use a new topological structure measure to analyze the local environment of 923 atom gold clusters quenched from the melt, at various quench rates, by molecular dynamics. The crystallization and geometrical rearrangements of the core atoms upon freezing can be clearly observed using our structure measure which is based on planar graphs. Our results support the hypothesis that crystallization is initiated from the surface and proceeds into the cluster core.

The Microstructure of Di-alkyl Chain Cationic/Nonionic Surfactant Mixtures: Observation of Coexisting Lamellar and Micellar Phases and Depletion Induced Phase Separation

The evolution of the microstructure and composition occurring in the aqueous solutions of di-alkyl chain cationic/nonionic surfactant mixtures has been studied in detail using small angle neutron scattering, SANS. For all the systems studied we observe an evolution from a predominantly lamellar phase, for solutions rich in di-alkyl chain cationic surfactant, to mixed cationic/nonionic micelles, for solutions rich in the nonionic surfactant. At intermediate solution compositions there is a region of coexistence of lamellar and micellar phases, where the relative amounts change with solution composition. A number of different di-alkyl chain cationic surfactants, DHDAB, 2HT, DHTAC, DHTA methyl sulfate, and DISDA methyl sulfate, and nonionic surfactants, C12E12 and C12E23, are investigated. For these systems the differences in phase behavior is discussed, and for the mixture DHDAB/C12E12 a direct comparison with theoretical predictions of phase behavior is made. It is shown that the phase separation that can occur in these mixed systems is induced by a depletion force arising from the micellar component, and that the size and volume fraction of the micelles are critical factors.

How much of a priority is treating erectile dysfunction? A study of patients' perceptions

BACKGROUND

Erectile dysfunction (ED) is one complication of diabetes for which the treatment is rationed. Despite considerable public debate there has been no formal assessment of the views of patients and sufferers of the priority of treating ED.

AIMS

To determine the perceptions of diabetic patients of the relative priority of treating ED in comparison with treatments for other diabetic complications and common medical conditions.

METHODS

Psychological measures were used to assess subjects' perceptions of the relative importance of ED in comparison with eight other common problems (blindness, foot ulcers, high blood pressure, impotence, kidney disease, high cholesterol, migraine, mild indigestion and sleeping difficulties). The concept of willingness to pay was used to assess the amount per month participants would be prepared to pay for treatment for ED and other conditions. Four groups (controls, healthy diabetic men, impotent diabetic men and impotent diabetic men not in a sexual relationship) were studied.

RESULTS

Significant differences were found between the four groups with regard to the ranking of the importance of ED compared with other health problems. Impotent diabetic male patients were prepared to pay more for treatment for their condition than all other conditions except blindness and renal failure.

CONCLUSIONS

Men with diabetes, in particular ED sufferers, believe ED has a major impact on quality of life and is as important to treat as many other conditions associated with diabetes.

Differential gene expression in a murine model of cancer cachexia

Murine adenocarcinoma 16 (MAC16) tumors and cell lines induce cachexia in NMRI nude mice, whereas histologically similar MAC13 tumors do not. After confirming these findings in BALB/c nude mice, we demonstrated that this tissue wasting was not related to decreased food intake or increased total body oxidative metabolism. Previous studies have suggested that MAC16's cachexigenic properties may involve the production of tumor-specific factors. We therefore screened for genes having increased expression in the MAC16 compared with the MAC13 cell line by performing hybridization to a murine cDNA expression array, by generation and comparison of cDNA libraries from each cell line, and by PCR-based subtractive hybridization. Northern blot hybridization was performed to confirm differences in transcript expression. Transcripts encoding insulin-like growth factor binding protein-4, cathepsin B, ferritin light and heavy chain, endogenous long-terminal repeat sequences, and a viral envelope glycoprotein demonstrated increased expression in the MAC16 cell line. The roles of a number of these genes in known metabolic pathways identify them as potential participants in the induction of cachexia.

Angiosarcoma of the breast following breast preservation therapy and local radiation therapy for breast cancer

This is a case of angiosarcoma following breast preservation therapy and local radiation therapy over a 3-year period.

Resistance to multiple steroids in two sisters

A 14-year-old Native American girl from the Iroquois Nation was referred as a potential patient with the syndrome of Apparent Mineralocorticoid Excess. Instead, her evaluation revealed resistance to glucocorticoids, mineralocorticoids, and androgens. She lacked Cushingoid features in spite of significantly high cortisol levels. Menstruation was regular and there was no clinical evidence of masculinization despite high serum androgen levels in the male range. The patient's sister had similar clinical features. Partial resistance to exogenous glucocorticoid and mineralocorticoid administration was well demonstrated in both patients. It is proposed that these patients represent the first cases of partial resistance to multiple steroids, possibly owing to a coactivator defect.

Resistance to several steroids in two sisters

A 14-yr-old native American girl from the Iroquois Nation was referred as a potential patient with the syndrome of apparent mineralocorticoid excess. Instead, her evaluation revealed resistance to glucocorticoids, mineralocorticoids, and androgens, but no resistance to vitamin D or thyroid hormones. She lacked Cushingoid features despite significantly high cortisol levels. Menstruation was regular, and there was no clinical evidence of masculinization despite high serum androgen levels in the male range. The patient's sister had similar clinical features. Partial resistance to exogenous glucocorticoid and mineralocorticoid administration was well demonstrated in both patients. It is proposed that these patients represent the first cases of partial resistance to multiple steroids, possibly due to a coactivator defect.

Activation of PPARgamma coactivator-1 through transcription factor docking

Transcriptional coactivators have been viewed as constitutively active components, using transcription factors mainly to localize their functions. Here, it is shown that PPARgamma coactivator-1 (PGC-1) promotes transcription through the assembly of a complex that includes the histone acetyltransferases steroid receptor coactivator-1 (SRC-1) and CREB binding protein (CBP)/p300. PGC-1 has a low inherent transcriptional activity when it is not bound to a transcription factor. The docking of PGC-1 to peroxisome proliferator-activated receptor gamma (PPARgamma) stimulates an apparent conformational change in PGC-1 that permits binding of SRC-1 and CBP/p300, resulting in a large increase in transcriptional activity. Thus, transcription factor docking switches on the activity of a coactivator protein.

Giant cell tumour of the retropharynx

AIMS

Giant cell tumours of soft tissues are usually of tenosynovial origin and are benign, slow growing neoplasms that have the capacity for local recurrence. They occur most frequently in the fingers and only rarely in the head and neck region. Their occurrence in the retropharynx has not been reported. The differential diagnoses of head and neck lesions containing giant cells are discussed.

METHODS AND RESULTS

We describe a case of a retropharyngeal giant cell tumour of tenosynovial type in a 48-year-old man. The clinical, radiological and histological features are reviewed. Immunohistochemical studies point to a possible histiocytic origin based on reactivity for CD68.

CONCLUSIONS

Tenosynovial giant cell tumour should be considered in the differential diagnosis of tumours arising in the retropharyngeal soft tissues.

Intensive chemotherapy and bone marrow rescue for young children with newly diagnosed malignant brain tumors

PURPOSE

To evaluate a strategy that avoids radiotherapy in children less than 6 years of age with newly diagnosed malignant brain tumors, by administering myeloablative consolidation chemotherapy with autologous bone marrow reconstitution (ABMR) after maximal surgical resection and conventional induction chemotherapy.

PATIENTS AND METHODS

Between March 1991 and April 1995, 62 children (median age, 30 months) with newly diagnosed malignant brain tumors were enrolled onto this trial. Children received conventional induction chemotherapy with vincristine, cisplatin, cyclophosphamide, and etoposide, repeated every 3 weeks for five cycles. Children without disease progression on induction chemotherapy were offered consolidation with myeloablative chemotherapy that incorporated carboplatin, thiotepa, and etoposide followed by ABMR. Irradiation was used only for residual tumor at consolidation or for progressive/recurrent disease.

RESULTS

Induction chemotherapy was well tolerated by most patients; however, progression was noted in 17 children (27%) and four (6%) died of treatment complications. Of 37 children who received consolidation chemotherapy with ABMR, 15 are free of disease progression (median post-ABMR without further treatment, >44 months). The remaining 22 all progressed within 15 months of ABMR; three of 37 (8%) died of treatment-related complications. The 3-year overall survival (OS) and event-free survival (EFS) rates from diagnosis for all children are 40% (95% confidence interval [CI], 28% to 52%) and 25% (95% CI, 13% to 37%), respectively. Radiotherapy was administered to 19 of 62 children: 17 for progressive disease (PD) and two for residual disease at the time of ABMR.

CONCLUSION

A significant proportion of children with malignant brain tumors can avoid radiotherapy and prolonged maintenance chemotherapy yet still achieve durable remission with this brief intensive chemotherapy regimen.

Myeloperoxidase mRNA analysis in acute lymphoblastic leukemia

Expression of the myeloperoxidase (MPO) gene at the mRNA level is a better lineage marker than enzymatic activity in early myeloid precursors and their leukemic counterparts. Its diagnostic use depends on the specificity of expression for myeloblasts and its absence in blasts of lymphoid lineage. The present study investigates MPO mRNA expression in adult acute lymphoblastic leukemia (ALL), using reverse transcription-polymerase chain reaction. Of a total of 13 cases, six were found to have blasts positive for MPO mRNA; in all of these cases, the blasts were cytochemically negative for MPO. This unexpected finding of MPO mRNA positivity in six of 13 cases was further investigated at the molecular level. Bcr gene rearrangement analysis was positive in all six cases for the bcr breakpoint diagnostic of chronic myelogenous leukemia (CML). Only three of these six cases were cytogenetically positive for a Philadelphia (Ph) chromosome. Based on molecular analysis, these cases are considered as CML presenting in blast crisis of lymphoid lineage, as opposed to de novo ALL. The remaining seven cases were Ph negative at the cytogenetic and molecular levels; the leukemic blasts were MPO mRNA negative, confirming the lack of MPO gene expression in de novo ALL.

Comparison of a weight-based heparin nomogram with traditional heparin dosing to achieve therapeutic anticoagulation

Optimum anticoagulation with heparin within the first 24 hours of a thrombotic event is critical in preventing a recurrence. We believed that traditional nonweight-based heparin dosing at our institution resulted in delayed anticoagulation. A weight-based heparin nomogram was therefore created and compared to traditional heparin dosing in patients with a diagnosis of acute deep vein thrombosis or pulmonary embolism. Fifty historical control patients were compared to 50 consecutive patients treated prospectively using the weight-based nomogram. The primary outcome assessed was time to achieve therapeutic anticoagulation, defined as an activated partial thromboplastin time (aPTT) of 46-70 seconds (1.5-2.5 times the control aPTT). The weight-based nomogram achieved an aPTT above the therapeutic threshold more rapidly than the control group (10.7 hrs nomogram vs 33.3 hrs control group, p < 0.004). Similarly, the proportion of patients who exceeded the therapeutic threshold at the first aPTT measurement, at 24 hours, and at 48 hours was significantly higher in the nomogram group. There was no difference in the frequency of bleeding complications or recurrent thrombotic events between the two groups. The initial nomogram was revised for patients weighing more than 80 kg owing to a greater frequency of excessive anticoagulation in these patients. Subsequent analysis of 29 patients using the modified nomogram revealed sustained efficacy and a reduced number of supratherapeutic aPTTs. We concluded that a weight-based heparin nomogram is superior to traditional therapy in achieving rapid therapeutic anticoagulation without an increase in adverse outcomes.

Is there a role for high-dose chemotherapy with stem cell rescue for brain stem tumors of childhood?

Diffuse pontine tumors are highly lethal and conventional therapy with irradiation provides long-term survival to a very small proportion of the patients. We have reported promising results using high-dose chemotherapy with autologous stem cell rescue in patients with recurrent high-grade astrocytomas in other anatomic locations, but our results and those of others have been very discouraging in children with brain stem tumors. Alternative strategies need to be developed for this highly lethal disease.

Gene transfer to synovial cells by intra-articular administration of plasmid DNA

We studied reporter gene expression in synovial tissue after intra-articular administration of an expression plasmid into the knees of rabbits and rats. In both species, administration of a plasmid encoding beta-galactosidase led to gene expression in the synovial cells lining the joint. Expression correlated with the presence of plasmid DNA in synovial tissue extracts. Studies with a plasmid encoding chloramphenicol acetyltransferase demonstrated that gene expression persists for 2-5 days after administration. Southern blotting demonstrated that the administered plasmid was taken up rapidly by synovial tissue and degraded. By 24 hr after administration, no intact plasmid could be detected by Southern blotting, although small amounts of plasmid could be amplified by PCR up to 7 days. Administration of a plasmid encoding human growth hormone demonstrated that this product could be expressed from synovial cells and secreted into the synovial fluid. The histological distribution of gene expression in synovium resembles the known distribution of particulate materials injected into the joint and suggests that plasmid DNA is taken up by nonspecific endocytosis like other particulate materials during the remodeling of synovial fluid.

Recombinant antibodies in bioactive peptide design

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is important in many immune and inflammatory processes. GM-CSF binds to specific cellular receptors which belong to a recently described supergene family. These receptors are potential targets for pharmacologic design, and such design depends on a molecular understanding of ligand-receptor interactions. One approach to dissecting out critical intermolecular interactions is to develop analogs of specific interaction sites of potential importance. Monoclonal antibodies have been employed for these purposes in prior studies. Here we present application of recombinant antibody technology to the development of analogs of a site on GM-CSF bound by a neutralizing anti-GM-CSF monoclonal antibody. Polyclonal antisera with high titer neutralizing activity against human GM-CSF were developed in BALB/c mice. Purified immunoglobulins were prepared and used to immunize syngeneic mice. Anti-anti-GM-CSF was developed which demonstrated biological antagonist activity against GM-CSF-dependent cellular proliferation. RNA was extracted from spleen cells of mice with biologically active anti-anti-GM-CSF, cDNA synthesized, and polymerase chain reaction performed with primers specific for murine kappa light chain V regions. Polymerase chain reaction products were cloned into the pDABL vector and an expression library developed. This was screened with anti-GM-CSF neutralizing mAb 126.213, and several binding clones isolated. One clone (23.2) which inhibited 126.213 binding to GM-CSF was sequenced revealing a murine kappa light chain of subgroup III. Comparison of the 23.2 sequence with the human GM-CSF sequence revealed only weak sequence similarity of specific complementarity determining regions (CDRs) with human GM-CSF. Structural analysis revealed potential mimicry of specific amino acids in the CDR I, CDR II and FR3 regions of 23.2 with residues on the B and C helices of GM-CSF. A synthetic peptide analog of the CDR I was bound by 126.213, specifically antagonized GM-CSF binding to cells and blocked GM-CSF bioactivity. These studies indicate the feasibility of using recombinant antibody libraries as sources of interaction site analogs.

Production of transgenic mice from cryopreserved fertilized ova

Cryopreserved fertilized mouse ova were used to generate transgenic mice via micromanipulation. Five-DNA constructions were injected into a total of 1,052 cryopreserved ova, of which 683 (65%) survived the injection and were transferred into recipients. Of 35 recipients, 66% became pregnant and littered a total of 88 pups. As controls, these DNA constructions were also injected into 1,123 fresh ova, of which 744 (66%) survived and were transferred. Of 42 recipients, 79% became pregnant and littered a total of 167 pups. That is, 22% of fresh ova that were transferred developed into live pups, whereas only 13% of cryopreserved ova did so. Of the pups born, 42 of the 167 (25%) produced from fresh ova were transgenic, and 28 of the 88 (32%) produced from cryopreserved ova were transgenic. In terms of the injected ova that had been transferred, 5.6% of the 744 fresh and 4.1% of the 683 frozen ova developed into transgenic mice. These data indicate that the efficiency of production of transgenic mice from cryopreserved ova is close to that from fresh ova. That observation and the fact that cryopreserved ova allow more efficient utilization of animals suggest that cryopreserved ova can be used instead of fresh ova to produce transgenic mice.

Comparison between the effects of inhaled isoprenaline and fenoterol on plasma cyclic AMP and heart rate in normal subjects

The time course of changes in plasma cyclic AMP, heart rate and bronchial tone after inhalation of fenoterol or isoprenaline from a dose-metered aerosol are reported in a group of normal subjects. After isoprenaline, plasma cyclic AMP increased rapidly reaching a peak by 10 min and returned to basal levels within 60 min. A rapid, transient rise in heart rate occurred that was maximal by 5 min and returned to a basal level by 45 min. After fenoterol, the changes in cyclic AMP and heart rate were of much longer duration. The rise in plasma cyclic AMP was slower in onset and of greater magnitude than for isoprenaline, reaching a peak by 20 min and remaining above basal level for more than 6 h. The maximum increase in heart rate after fenoterol was less than that observed with isoprenaline but an elevated rate persisted for 4 h after inhalation of fenoterol. Fenoterol is known to have a longer duration of action as a bronchodilator in comparison with isoprenaline. The prolonged rise in plasma cyclic AMP in normal subjects given inhaled fenoterol may reflect this long duration of action. The concomitant rise in heart rate, however, suggests that the duration of plasma cyclic AMP response may in part be due to the systemic effect of the fraction of inhaled fenoterol known to be absorbed via the buccal and intestinal routes.

Endoscopic sphincterotomy in the management of biliary tract disease

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