Sphingosine‑1‑phosphate analogue FTY720 exhibits a potent anti‑proliferative effect on glioblastoma cells

Sphingosine‑1‑phosphate (S1P) plays a key role in cell survival, growth, migration, and in angiogenesis. In glioma, it triggers the activity of the S1P‑receptor 1 and of the sphingosine kinase 1; thus influencing the survival rate of patients. The aim of the present study was to investigate the anti‑proliferative effect of the S1P analogue FTY720 (fingolimod) in glioblastoma (GBM) cells. A172, G28, and U87 cells were incubated with micromolar concentrations of FTY720 or temozolomide (TMZ) for 24 to 72 h. Proliferation and half maximal inhibitory concentration (IC50) were determined by using the xCELLigence system. FACS analysis was performed to check the cell cycle distribution of the cells after a 72‑h incubation with FTY720. This was then compared to TMZ‑incubated and to untreated cells. Gene expression was detected by RT‑qPCR in A172, G28, U87 and three primary GBM‑derived cell lines. FTY720 was able to reduce the number of viable cells. The IC50 value was 4.6 µM in A172 cells, 17.3 µM in G28 cells, and 25.2 µM in U87 cells. FTY720 caused a significant arrest of the cell cycle in all cells and stabilized or over‑expressed the level of AKT1, MAPK1, PKCE, RAC1, and ROCK1 transcripts. The TP53 transcript level remained stable or was downregulated after treatment with FTY720. FTY720 may be a promising target drug for the treatment of GBM, as it has a strong anti‑proliferative effect on GBM cells.

Percutaneous minimally invasive fetoscopic surgery for spina bifida aperta. Part III: neurosurgical intervention in the first postnatal year

OBJECTIVE

To evaluate the need for postnatal neurosurgical intervention after fetoscopic patch coverage of spina bifida aperta (SBA).

METHODS

This was a retrospective analysis of a cohort of 71 fetuses which underwent minimally invasive fetoscopic patch coverage of SBA between 21 + 0 and 29 + 1 weeks of gestation. Postnatal neurosurgical procedures were classified into two types: re-coverage of the SBA within the first 3 months following birth, and shunt placement as treatment of associated hydrocephalus within the first year.

RESULTS

Location of the SBA was lumbosacral in 59 cases, lumbar in seven, thoracic in three and sacral in two. In total, 20/71 (28%) patients underwent early postnatal neurosurgical intervention by means of re-coverage of the SBA. This was performed because of cerebrospinal fluid leakage in seven (35%), adhesions with functional deterioration in three (15%), incomplete coverage in five (25%) and skin defect in five (25%) cases. Ventriculoperitoneal shunt placement within 1 year was required in 32 (45%) cases and was preceded by ventriculostomy in two. Three (4%) infants needed Chiari decompression surgery in the first 12 months following birth, because of syringomyelia or gait disturbance.

CONCLUSIONS

Fetoscopic patch coverage of SBA may require postnatal re-coverage in some cases. In most cases, conservative wound treatment shows good results, without requiring neurosurgical intervention. The low 1-year-shunt rate is comparable to data of the Management of Myelomeningocele Study and lower compared with published data of patients with postnatal only coverage of SBA.

PD06-05: Primary and Secondary Pegfilgrastim Utilization in Adjuvant Chemotherapy for Breast Cancer in the Community

Background

Various factors are taken into consideration in the selection of adjuvant breast cancer (BC) chemotherapy (CT) regimens for patients. Choice of CT, schedule, duration, and supportive care affects costs and toxicity. Understanding clinical practice utilization patterns are important when making cost estimates of adjuvant therapy. Because pegfilgrastim is a large driver of cost it is important to understand the utilization characteristics. We aimed to characterize primary and secondary pegfilgrastim use during neoadjuvant/adjuvant (N/Ad) chemotherapy by regimen type. While initial data suggests the incidence of febrile neutropenia (FN) is low among some docetaxel containing regimens, we wanted to further characterize pegfilgrastim utilization, as previous utilization studies suggested it was higher than expected.

Methods: Using the US Oncology iKnowMed™ EHR database, we retrospectively identified female BC patients (pts) diagnosed with stage I-III BC, between 7/2006 and 11/2010. Secondary diagnoses were excluded. Pts were characterized by age, ER and HER2 status, tumor size, grade, and nodes. CT utilization was determined by the number of pts assigned an N/Ad line of therapy (LOT) during the study period. Regimens were categorized by CT title and drugs. Clinical trial pts were included. Pegfilgrastim utilization was characterized if administered within 6 months of being assigned to an N/Ad CT regimen, and was captured as primary prophylaxis if the first dose was administered <5 days of C1D1 of a regimen, and secondary prophylaxis if >5days.

Results: General chemotherapy and pegfilgrastim utilization characteristics were previously reported. This report captures primary vs. secondary pegfilgrastim use. During the time period, 40,881 BC pts were identified. Of these, 15,328 pts (37%) were assigned an N/Ad CT regimen and 72% (11, 022 pts) received pegfilgrastim at any time within 6 months of their N/Ad regimen. Docetaxel containing regimens (TC, TAC, TCH) and dose-dense regimens accounted for the majority of all pegfilgrastim use. Pegfilgrastim utilization with the TC regimen was 70%, and represented 25% of all N/Ad pegfilgrastim utilization. The vast majority of utilization for TC and TCH was primary prophylaxis as detailed below:

Utilization of pegfilgrastim in adjuvant chemotherapy regimens for breast cancer in the community

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Background: Selection of adjuvant breast cancer (BC) therapy varies based on patient risk factors. Choice of chemotherapy (CT), schedule, duration, and supportive care affects costs and toxicity. Because pegfilgrastim (PEG) is a large driver of cost in adjuvant therapy it is important to understand the utilization characteristics. We aimed to characterize PEG utilization during neoadjuvant/adjuvant (N/Ad) CT by age and regimen type.

Methods: Using the US Oncology iKnowMed EHR database, we retrospectively identified female BC patients (pts) diagnosed with stage I-III BC, between 7/2006 and 11/2010. Secondary diagnoses were excluded. Pts were characterized by age, ER and HER2 status, tumor size, grade, and nodes. CT utilization was determined by the number of pts assigned an N/Ad line of therapy (LOT) during the study period. Regimens were categorized by CT title and drugs. Clinical trial pts were included. PEG utilization was characterized if administered within 6 months of being assigned to an N/Ad CT regimen.

Results: During the time period, 40,881 newly diagnosed localized BC pts were identified. Of these, 15,328 pts (37%) were assigned an N/Ad CT regimen and 72% (11, 022 pts) received PEG at any time within 6 months of their N/Ad CT. When analyzed by regimen type, TC, TAC, TCH, and dose-dense AC-paclitaxel were the most highly utilized regimens accounting for 64% of all PEG use. PEG use with the TC regimen was 70% and represented 25% of all N/Ad PEG utilization. PEG utilization by age was characterized as 81% of pts <40 yrs, 74% of pts 40-49 yrs, 70% of pts 50-59 yrs, 71% of pts 60-69 yrs, 68% of pts 70-79 yrs, and 40% of pts ≥80 yrs.

Conclusions: While 37% of women treated in the N/Ad setting received CT, PEG was given to 72% of that subset. Utilization was high among all age groups. Dose-dense and docetaxel-containing regimens accounted for the majority of PEG use. With availability of generic docetaxel, commonly used drugs in adjuvant BC except trastuzumab will have generic equivalents and PEG will be the largest cost driver in women receiving adjuvant CT in the community. Since febrile neutropenia occurred in 5% of pts on the original TC trial, determination of appropriate level of use of PEG in the adjuvant setting needs further study.

Systematic review of noninvasive positive pressure ventilation in severe stable COPD

The present systematic review examined the effectiveness of bilevel noninvasive positive pressure ventilation (NIPPV) in the management of chronic respiratory failure (CRF) due to severe stable chronic obstructive pulmonary disease (COPD). Randomised controlled trials (RCTs) and non-RCTs (crossover design) of adults with severe stable COPD and CRF receiving bilevel NIPPV via nasal, oronasal or total face mask were identified from electronic databases and manual screening of journals and reference lists. Respiratory function (gas exchange, lung function, ventilatory/breathing pattern, respiratory muscle function and work of breathing) and health-related outcomes (dyspnoea, functional status, exercise tolerance, health-related quality of life (HRQOL), morbidity and mortality) were assessed. In total, 15 studies met the inclusion criteria: six RCTs and nine non-RCTs. RCTs did not find improved gas exchange with bilevel NIPPV, while non-RCTs did. Lung hyperinflation and diaphragmatic work of breathing were reduced in a nonrandomised subset. HRQOL and dyspnoea, the least studied outcomes, showed improvement with bilevel NIPPV. In a subset of individuals on maximal medical treatment regimes for severe stable chronic obstructive pulmonary disease, bilevel noninvasive positive pressure ventilation may have an adjunctive role in the management of chronic respiratory failure through attenuation of compromised respiratory function and improvement in health-related outcomes.

Evaluation of Tomudex in patients with recurrent or metastatic squamous cell carcinoma of the head and neck: a Southwest Oncology Group study

A phase II trial of Tomudex (raltitrexed, ZD 1694), a new thymidylate synthase inhibitor, was performed in patients with recurrent or metastatic squamous cell carcinoma of the head and neck. This trial demonstrated that Tomudex was well tolerated in this patient population. Nausea and vomiting were minimal, and hematologic toxicities were relatively infrequent. Only one patient was withdrawn from the study due to toxicity (grade 4 diarrhea). One patient exsanguinated from a rent in the carotid artery in an area of tumor involvement, and was categorized as a grade 5 toxicity. Thus 25/27 patients were able to complete at least 2 cycles of treatment. Tomudex demonstrated a 3.7% response rate (95% CI 0.1-19%), with a median survival of 6 months in this highly resistant disease population. Tomudex is not considered active enough as monotherapy for further evaluation in this disease population.

Glanzmann thrombasthenia due to a two amino acid deletion in the fourth calcium-binding domain of alpha IIb: demonstration of the importance of calcium-binding domains in the conformation of alpha IIb beta 3

The integrin alpha IIb beta 3, a calcium-dependent heterodimer, plays a critical role in platelet aggregation. The alpha IIb subunit of the heterodimer contains four highly conserved putative calcium-binding domains in its extracellular portion. During studies of the molecular basis of Glanzmann thrombasthenia in a child of mixed Caucasian background whose platelets expressed little alpha IIb beta 3 on their surface, we found the patient heterozygous for a two amino acid deletion in the fourth alpha IIb calcium-binding domain. When this alpha IIb mutant was expressed in COS-1 cells, we found that the deletion did not interfere with the assembly of alpha IIb beta 3 heterodimers, but altered their conformation such that they were neither recognized by the heterodimer-specific antibody A2A9 nor able to undergo further intracellular processing or transport to the cell surface. These results suggest that the calcium-binding domains in alpha IIb play an important role maintaining the overall conformation of alpha IIb beta 3. To confirm this suggestion, we deleted each of the four 12 amino acid calcium-binding domains in alpha IIb by in vitro mutagenesis and expressed the mutants along with beta 3 in COS-1 cells. Each construct formed a heterodimer with beta 3, but none of the heterodimers interacted with A2A9 or underwent further intracellular processing. These data indicate that the calcium-binding domains in alpha IIb are not involved in alpha IIb beta 3 heterodimer formation, but their presence is required for the intracellular transport of alpha IIb beta 3 to the cell surface.

Determinants of the intracellular fate of truncated forms of the platelet glycoproteins IIb and IIIa

The platelet glycoproteins GPIIb and GPIIIa are integral membrane proteins and form calcium-dependent heterodimers in the endoplasmic reticulum (ER). In the absence of heterodimer formation, GPIIb and GPIIIa are retained in the ER and degraded. To produce soluble forms of these proteins, we truncated each at a site just proximal to its transmembrane anchor and expressed the mutants in COS-1 cells. We found that both truncated GPIIIa (GPIIIatr) and GPIIIatr were secreted by the transfected cells. However, GPIIbtr was retained by the cells and was immunoprecipitated as a doublet with a 115,000 molecular weight protein. Incubation of transfected cells with the calcium ionophore A23187 or the calcium chelator 1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl) ester (BAPTA-AM) failed to induce appreciable GPIIbtr secretion, suggesting that formation of intracellular calcium complexes was not a factor in GPIIbtr retention. Further, immunoblotting of immunoprecipitated GPIIbtr and GPIIIatr revealed that the chaperone binding protein (BiP) was associated with each, arguing that BiP alone was not responsible for GPIIbtr retention. These studies indicate that the intracellular retention of GPIIIa involves sequences located in the transmembrane or cytoplasmic domains of the molecule. GPIIb contains an additional retention signal located in the extracellular portion of the molecule whose effect is abrogated by formation of a GPIIb-IIIa heterodimer. This signal may be involved in the fate of nascent GPIIb monomers and the generation of correctly configured GPIIb-IIIa heterodimers.

Disorders of platelet function

Platelets provide for primary hemostasis by forming a hemostatic plug at sites of vascular damage. They also provide a surface for the assembly of the coagulation protein complexes that generate thrombin, serve as a nidus for fibrin clots, and secrete factors involved in wound repair. Normal platelet function can be divided into four phases: adhesion, aggregation, secretion, and expression of procoagulant activity. Platelet adhesion initiates plug formation as platelets adhere to the connective tissue at the edges of a wound within seconds after vascular damage. When damage occurs in regions of slow blood flow, platelets adhere to subendothelial collagen, fibronectin, and laminin. However, when damage occurs in regions of rapid flow, platelet adhesion requires the presence of subendothelial von Willebrand factor (vWf) and a specific platelet receptor, the glycoprotein Ib/IX (GPIb/IX) complex. Following initial adhesion, platelets aggregate to complete the formation of a hemostatic plug. Platelet aggregation requires active platelet metabolism, platelet stimulation by agonists such as ADP, thrombin, collagen, or epinephrine; the presence of calcium or magnesium ions and specific plasma proteins such as fibrinogen or vWf; and a platelet receptor, the glycoprotein IIb/IIIa (GPIIb/IIIa) complex. Thus, platelet stimulation results in the generation of intracellular second messengers that transmit the stimulus back to the platelet surface, exposing protein binding sites on GPIIb/IIIa. Fibrinogen (or vWf) then binds to GPIIb/IIIa and crosslinks adjacent platelets to produce platelet aggregates. Platelet stimulation also results in platelet secretion and the elaboration of platelet procoagulant activity. During secretion, substances are released to propagate the aggregation response and to promote wound healing; the expression of procoagulant activity localizes thrombin generation to the site of vascular damage. Disorders of platelet function can be divided into those of congenital and those of acquired origin. Although congenital disorders are uncommon, acquired disorders are encountered frequently in clinical practice. Congenital absence of GPIb/IX and GPIIb/IIIa results in the Bernard-Soulier syndrome (BSS) and Glanzmann thrombasthenia (GT), respectively. Each is an autosomal recessive bleeding disorder in which absence of a protein complex renders the affected platelets incapable of undergoing either vWf-mediated adhesion (BSS) or fibrinogen-mediated aggregation (GT).(ABSTRACT TRUNCATED AT 400 WORDS)

Study of the endoproteolytic cleavage of platelet glycoprotein IIb using oligonucleotide-mediated mutagenesis

The precursor of platelet membrane glycoprotein IIb (GPIIb) undergoes endoproteolytic cleavage into heavy and light chains post-translation. Endoproteolysis occurs within a 17-amino acid stretch of the precursor that contains 4 arginine residues, 3 in dibasic sequences [Lys-Arg (855-856) and Arg-Arg (858-859)] and a single arginine at 871. To determine the site of GPIIb cleavage and its role in the function of the glycoprotein IIb/IIIa heterodimer, we mutated arginine 856, the di-arginine sequence 858-859, and arginine 871 and coexpressed the mutants with glycoprotein IIIa (GPIIIa) in COS-1 cells. Each GPIIb mutant formed recombinant GPIIb-IIIa heterodimers, but mutants lacking arginine at 856 or 858-859 failed to undergo cleavage. Nevertheless, heterodimers containing the uncleaved GPIIb were expressed on the cell surface. Because endoproteolysis most often occurs after arginines in dibasic sequences, we next expressed GPIIb mutants containing lysine at 856 or aspartic acid at 855 with GPIIIa. Both mutants were cleaved and surface-expressed, indicating that the dibasic sequence at 858-859, but not at 855-856, is required for GPIIb cleavage. Lastly, we tested the function of GPIIb-IIIa containing uncleaved GPIIb by measuring adhesion of transfected cells to immobilized fibrinogen. We found no difference in the adhesion of cells expressing either wild-type or mutant GPIIb, indicating GPIIb-IIIa heterodimers containing uncleaved GPIIb maintain their ability to interact with fibrinogen.

Effect of deletion of glycoprotein IIb exon 28 on the expression of the platelet glycoprotein IIb/IIIa complex

We have isolated from an HEL cell cDNA library an alternatively spliced transcript for the platelet membrane glycoprotein IIb (GPIIb) that resulted from the deletion of the 34 amino acids of exon 28 of the GPIIb gene. Confirming an earlier report, we also detected this transcript in platelet mRNA. To determine the consequences of exon 28 deletion on the expression of the GPIIb/IIIa heterodimer, we expressed cDNA for GPIIb-28 in COS-1 cells, either individually or simultaneously with a cDNA for GPIIIa. When recombinant GPIIb-28 was expressed alone, it did not acquire resistance to the enzyme endo-beta-N-acetylglucosaminidase H, was not cleaved into heavy and light chains, and was not transported to the cell surface. However, when recombinant GPIIb-28 was coexpressed with recombinant GPIIIa, GPIIb/IIIa heterodimers were assembled. Nevertheless, these heterodimers failed to complete posttranslational processing and were degraded intracellularly. Exon 28 contains one site for Asn-linked glycosylation. To determine if loss of this glycosylation site was responsible for the effects of exon 28 deletion, we removed the site from the exon 28 of intact GPIIb by oligonucleotide-mediated mutagenesis. However, absence of the carbohydrate appended to exon 28 did not prevent normal GPIIb/IIIa heterodimer expression. Our studies indicate that absence of the amino acids encoded by GPIIb exon 28 sufficiently perturbs the quaternary configuration of the GPIIb/IIIa heterodimer to impair its subsequent intracellular transport and processing. They also indicate that this alternatively spliced form of GPIIb mRNA, although present in megakaryocytes, is unlikely to make a significant contribution to the GPIIb/IIIa complexes expressed on platelets.