Farjana B. Rowther

Plasma Membrane Calcium ATPase Isoform 4 Inhibits Vascular Endothelial Growth Factor–Mediated Angiogenesis Through Interaction With Calcineurin

Objective— Vascular endothelial growth factor (VEGF) has been identified as a crucial regulator of physiological and pathological angiogenesis. Among the intracellular signaling pathways triggered by VEGF, activation of the calcineurin/nuclear factor of activated T cells (NFAT) signaling axis has emerged as a critical mediator of angiogenic processes. We and others previously reported a novel role for the plasma membrane calcium ATPase (PMCA) as an endogenous inhibitor of the calcineurin/NFAT pathway, via interaction with calcineurin, in cardiomyocytes and breast cancer cells. However, the functional significance of the PMCA/calcineurin interaction in endothelial pathophysiology has not been addressed thus far. Approach and Results— Using in vitro and in vivo assays, we here demonstrate that the interaction between PMCA4 and calcineurin in VEGF-stimulated endothelial cells leads to downregulation of the calcineurin/NFAT pathway and to a significant reduction in the subsequent expression of the NFAT-dependent, VEGF-activated, proangiogenic genes RCAN1.4 and Cox-2. PMCA4-dependent inhibition of calcineurin signaling translates into a reduction in endothelial cell motility and blood vessel formation that ultimately impairs in vivo angiogenesis by VEGF. Conclusions— Given the importance of the calcineurin/NFAT pathway in the regulation of pathological angiogenesis, targeted modulation of PMCA4 functionality might open novel therapeutic avenues to promote or attenuate new vessel formation in diseases that occur with angiogenesis.

Prospective Comparison of Eubacterial PCR and Measurement of Procalcitonin Levels with Blood Culture for Diagnosing Septicemia in Intensive Care Unit Patients

ABSTRACT Rapid identification of infection has a major impact on the clinical course, management, and outcome of critically ill intensive care unit (ICU) patients. We compared the results of PCR and procalcitonin with blood culture for ICU patients suspected of having septicemia. Ninety patients (60 patients meeting the criteria for sepsis and 30 patients not meeting the criteria for sepsis) were evaluated. Compared with blood culture as the gold standard, the sensitivity, specificity, and positive and negative predictive values for PCR were 100%, 43.33%, 46.87%, and 100%, respectively, and for procalcitonin were 100%, 61.66%, 56.6%, and 100%, respectively. The average times required to produce a final result were as follows: PCR, 10 h; blood culture, 33 h; procalcitonin, 45 min. Both PCR and procalcitonin may be useful as rapid tests for detecting septicemia but compared with blood cultures lacked specificity.

Bromocriptine and dopamine mediate independent and synergistic apoptotic pathways in pituitary cells.

Dopamine (DA) agonists are the primary treatment choice for prolactinoma, effectively suppressing prolactin expression and reducing tumour size. However, the intracellular pathway(s) through which either DA or its agonists impact on proliferation or lead to tumour shrinkage are incompletely understood. To identify the mediators in the apoptotic cascades after DA or DA agonist challenges we used a well-characterized model system, the rodent somatolactotroph cell line GH3. In these cells, we show that apoptosis induced by the DA agonist bromocriptine (BC), but not DA, is initiated through activation of the JNK pathway. However, both DA and BC activate the terminal effector caspase, caspase-3. Kinetic studies and chemical inhibitor co-incubation experiments support a role for JNK activation preceding caspase-9 activation in BC challenged cells, however, engagement of these mediators was not apparent in DA challenge cells. These studies suggest that apoptosis induced by BC or DA is mediated through distinct and independent pathways that converge with activation of the terminal caspase, caspase-3. These observations were further reinforced by our findings that DA and BC, in co-incubation experiments, synergistically induce apoptosis. These findings raise the possibility that drugs acting through the same pathway as DA may be clinically beneficial when combined with BC.

Cyclic nucleotide phosphodiesterase‐1C (PDE1C) drives cell proliferation, migration and invasion in glioblastoma multiforme cells in vitro

Cyclic nucleotides (cAMP & cGMP) are critical intracellular second messengers involved in the transduction of a diverse array of stimuli and their catabolism is mediated by phosphodiesterases (PDEs). We previously detected focal genomic amplification of PDE1C in >90 glioblastoma multiforme (GBM) cells suggesting a potential as a novel therapeutic target in these cells. In this report, we show that genomic gain of PDE1C was associated with increased expression in low passage GBM‐derived cell cultures. We demonstrate that PDE1C is essential in driving cell proliferation, migration and invasion in GBM cultures since silencing of this gene significantly mitigates these functions. We also define the mechanistic basis of this functional effect through whole genome expression analysis by identifying down‐stream gene effectors of PDE1C which are involved in cell cycle and cell adhesion regulation. In addition, we also demonstrate that Vinpocetine, a general PDE1 inhibitor, can also attenuate proliferation with no effect on invasion/migration. Up‐regulation of at least one of this gene set (IL8, CXCL2, FOSB, NFE2L3, SUB1, SORBS2, WNT5A, and MMP1) in TCGA GBM cohorts is associated with worse outcome and PDE1C silencing down‐regulated their expression, thus also indicating potential to influence patient survival. Therefore we conclude that proliferation, migration, and invasion of GBM cells could also be regulated downstream of PDE1C.

Development of a novel, multifunctional, membrane-interactive pyridinium salt with potent anticancer activity.

The synthesis and biological evaluation of a novel pyridinium salt is reported. Initial membrane interaction with isolated phospholipid monolayers was obtained with the pyridinium salt, and two neutral analogues for comparison, and the anticancer effects of the best compound established using a cytotoxicity screening assay against glioma cells using both an established cell line and three short-term cell cultures-one of which has been largely resistant to all chemotherapeutic drugs tested to date. The results indicate that the pyridinium salt exhibits potent anticancer activity (EC50s=9.8-312.5 μM) on all cell types, including the resistant one, for a continuous treatment of 72 h. Microscopic examination of the treated cells using a trypan blue exclusion assay showed membrane lysis had occurred. Therefore, this letter highlights the potential for a new class of pyridinium salt to be developed as a much needed alternative treatment for glioma chemotherapy.

An Improved Method of Elimination of DNA from PCR Reagents

AbstractObjective: The presence of exogenous DNA in commercially available polymerase chain reaction (PCR) reagent preparations is a serious problem when amplifying conserved regions of bacteria. The preferred and currently in-use method of decontamination using 8-methoxypsoralen (8-MOP) and UVA requires re-standardization of decontamination with increasing concentrations of 8-MOP and UVA irradiation timings, if the DNA load of reagents is high due to lot-to-lot differences. The objective of this study was to develop a decontamination method, which would (i) work at the minimum reported concentration of 8-MOP and UVA irridation timings; and (ii) take care of inter-batch DNA-load variability of reagents. Materials and methods: The improved method described here was formulated after studying the exact molecular mechanism of action of 8-MOP with DNA. The successful working of the method was experimentally proven and validated with 6–7 new batches of PCR reagents. The sensitivity of eubacterial PCR, after using the new method of decontamination, to be used clinically was checked with both the spiked specimens and the actual clinical specimens. Results and discussion: The new method was found to work at the same starting parameters of 8-MOP and UVA in such situations. The increased efficiency of this method was found to be due to the synergistic effect of both the selective treatment of Taq DNA polymerase and the split-irradiation approach.

TOUCH-UP Gradient Amplification Method

We report a unique amplification technique that works efficiently and specifically over a temperature range, rather than at one specific temperature, throughout the amplification process. As bisulfite-modified DNA is one of the difficult to amplify templates, we used this technique to amplify regions of promoter-associated CpG island for 11 genes using this template. This technique amplified specific products for every gene without requiring any optimization.

Selective inhibition of plasma membrane calcium ATPase 4 improves angiogenesis and vascular reperfusion

AIMS Ischaemic cardiovascular disease is a major cause of morbidity and mortality worldwide. Despite promising results from pre-clinical animal models, VEGF-based strategies for therapeutic angiogenesis have yet to achieve successful reperfusion of ischaemic tissues in patients. Failure to restore efficient VEGF activity in the ischaemic organ remains a major problem in current pro-angiogenic therapeutic approaches. Plasma membrane calcium ATPase 4 (PMCA4) negatively regulates VEGF-activated angiogenesis via inhibition of the calcineurin/NFAT signalling pathway. PMCA4 activity is inhibited by the small molecule aurintricarboxylic acid (ATA). We hypothesize that inhibition of PMCA4 with ATA might enhance VEGF-induced angiogenesis. METHODS AND RESULTS We show that inhibition of PMCA4 with ATA in endothelial cells triggers a marked increase in VEGF-activated calcineurin/NFAT signalling that translates into a strong increase in endothelial cell motility and blood vessel formation. ATA enhances VEGF-induced calcineurin signalling by disrupting the interaction between PMCA4 and calcineurin at the endothelial-cell membrane. ATA concentrations at the nanomolar range, that efficiently inhibit PMCA4, had no deleterious effect on endothelial-cell viability or zebrafish embryonic development. However, high ATA concentrations at the micromolar level impaired endothelial cell viability and tubular morphogenesis, and were associated with toxicity in zebrafish embryos. In mice undergoing experimentally-induced hindlimb ischaemia, ATA treatment significantly increased the reperfusion of post-ischaemic limbs. CONCLUSIONS Our study provides evidence for the therapeutic potential of targeting PMCA4 to improve VEGF-based pro-angiogenic interventions. This goal will require the development of refined, highly selective versions of ATA, or the identification of novel PMCA4 inhibitors.

144 Selective inhibition of plasma membrane calcium atpase 4 improves vegf-mediated angiogenesis

Ischaemic cardiovascular disease is the leading cause of death worldwide. Therapeutic angiogenesis aims to stimulate the growth of new blood vessels from pre-existing ones to reperfuse ischaemic tissues. Our laboratory is characterising the molecular mechanisms that regulate activation of the calcineurin/NFAT pathway during VEGF-induced angiogenesis. We recently showed that the Plasma Membrane Calcium ATPase 4 (PMCA4) negatively regulates angiogenesis by establishing a molecular interaction with calcineurin. The identification of aurintricarboxylic acid (ATA) as an inhibitor of PMCA4 prompted us to hypothesise that ATA will enhance VEGF-induced angiogenesis. Consistent with this hypothesis, we demonstrate in this work that inhibition of PMCA4 by treatment with ATA significantly increases the activity of calcineurin/NFAT signalling, and the subsequent expression of the NFAT-dependent, pro-angiogenic protein RCAN1.4 in VEGF-stimulated endothelial cells. Targeting PMCA4 with ATA significantly reduces the level of membrane-associated calcineurin, and the amount of calcineurin co-precipitated with PMCA4 in immunoprecipitation assays, indicating that ATA promotes disruption of the PMCA4/calcineurin interaction. ATA robustly enhances endothelial cell motility, and in vitro and in vivo blood vessel formation, with no harmful effects to the cells. Interestingly, incubation of HUVECs with low concentration of ATA had no effect on the viability of the cells or the development of zebra fish embryos. However, higher ATA concentrations were associated with cellular and embryo toxicity. Our study provides evidence for the therapeutic potential of targeting endothelial PMCA4 to improve VEGF-based pro-angiogenic interventions, and highlights possible clinical applications for PMCA4 inhibitors in the treatment of ischaemic cardiovascular disease.

P5 Pharmacological inhibition of plasma membrane calcium ATPASE 4 improves VEGF-induced angiogenesis

Ischaemic cardiovascular diseases are the leading cause of death worldwide and are often associated with partial or full occlusion of the blood vessel network in the affected organs. Therapeutic angiogenesis provides a valuable tool for treating cardiovascular diseases by stimulating the growth of new blood vessels from pre-existing ones. The pro-angiogenic factor Vascular Endothelial Growth Factor (VEGF) has been identified as a crucial regulator of angiogenesis through activation of the calcineurin/Nuclear Factor of Activated T-cells (NFAT) signalling pathway. We have previously reported a novel role for the Plasma Membrane Calcium ATPase 4 (PMCA4) as a negative regulator of angiogenesis via interaction with calcineurin. Aurintricarboxylic acid (ATA) has been recently identified as a PMCA4-specific inhibitor. We hypothesise that pharmacological inhibition of PMCA4 with ATA will enhance VEGF-mediated angiogenesis. Here, we show that treatment of endothelial cells with nanomolar concentrations of ATA notably enhances calcineurin/NFAT signalling, and the subsequent expression of the VEGF-induced, NFAT-dependent, pro-angiogenic protein RCAN1.4. Targeting PMCA4 with ATA reduces the level of membrane-associated calcineurin, and the amount of calcineurin co-precipitated with PMCA4 in immunoprecipitation assays, indicating that ATA promotes disruption of the PMCA4/calcineurin interaction. ATA mediated inhibition of PMCA4 also enhances endothelial cell motility, and both in vitro and in vivo blood vessel formation. Low concentrations of ATA do not have any deleterious effects on the viability of endothelial cells or the development of zebra fish embryos, highlighting the potential clinical use of ATA, at low concentrations, to improve blood vessel formation in patients with ischaemic cardiovascular diseases.