Tax-interacting protein 1 coordinates the spatiotemporal activation of Rho GTPases and regulates the infiltrative growth of human glioblastoma

PDZ domains represent one group of the major structural units that mediate protein interactions in intercellular contact, signal transduction and assembly of biological machineries. TIP-1 protein is composed of a single PDZ domain that distinguishes TIP-1 from other PDZ domain proteins that more often contain multiple protein domains and function as scaffolds for protein complex assembly. However, the biological functions of TIP-1, especially in cell transformation and tumor progression, are still controversial as observed in a variety of cell types. In this study, we have identified ARHGEF7, a guanine nucleotide exchange factor (GEF) for Rho GTPases, as one novel TIP-1 interacting protein in human glioblastoma cells. We found that the presence of TIP-1 protein is essential to the intracellular redistribution of ARHGEF7 and rhotekin, one Rho effector, and the spatiotemporally coordinated activation of Rho GTPases (RhoA, Cdc42 and Rac1) in migrating glioblastoma cells. TIP-1 knockdown resulted in both aberrant localization of ARHGEF7 and rhotekin, as well as abnormal activation of Rho GTPases that was accompanied with impaired motility of glioblastoma cells. Furthermore, TIP-1 knockdown suppressed tumor cell dispersal in orthotopic glioblastoma murine models. We also observed high levels of TIP-1 expression in human glioblastoma specimens, and the elevated TIP-1 levels are associated with advanced staging and poor prognosis in glioma patients. Although more studies are needed to further dissect the mechanism(s) by which TIP-1 modulates the intracellular redistribution and activation of Rho GTPases, this study suggests that TIP-1 holds potential as both a prognostic biomarker and a therapeutic target of malignant gliomas.

Assessment of Infant Movement With a Compact Wireless Accelerometer System

There is emerging data that patterns of motor activity early in neonatal life can predict impairments in neuromotor development. However, current techniques to monitor infant movement mainly rely on observer scoring, a technique limited by skill, fatigue, and inter-rater reliability. Consequently, we tested the use of a lightweight, wireless, accelerometer system that measures movement and can be worn by premature babies without interfering with routine care. We hypothesized that this system would be useful in assessing motor activity, in identifying abnormal movement, and in reducing the amount of video that a clinician would need to review for abnormal movements. Ten preterm infants in the NICU were monitored for 1 h using both the accelerometer system and video. A physical therapist trained to recognize cramped-synchronized general movements scored all of the video data by labeling each abnormal movement observed. The parameters of three different computer models were then optimized based on correlating features computed from accelerometer data and the observer’s annotations. The annotations were compared to the model’s prediction on unseen data. The trained observer identified cramped-synchronized general movements in 6 of the 10 infants. The computer models attained between 70% and 90% accuracy when predicting the same observer label for each data point. Our study suggests that mini-accelerometers may prove useful as a clinical tool assessing patterns of movement in preterm infants.

Acute hepatitis C virus in an HIV clinic: a screening strategy, risk factors, and perception of risk

Acute hepatitis C virus (HCV) infection is being acquired undetected among HIV-infected individuals. A practical way to regularly screen HIV-infected patients for acute HCV irrespective of perceived risk or symptoms is needed. We piloted implementation of an acute HCV screening strategy using routine HIV clinical care schedules and the least costly blood tests, in a Rhode Island HIV care center. Study participants had ongoing HCV risk, completed questionnaires encompassing risk behaviors and perception of risk, and were screened with quarterly alanine aminotransferase (ALT). ALT rise triggered HCV RNA testing, with pooled rather than individual specimen HCV RNA testing for underinsured participants. Participants were primarily older, college-educated men who have sex with men (MSM) with history of sexually transmitted infection other than HIV. One of 58 participants developed acute HCV in 50 person-years of observation for an annual incidence of 2.0% per year (95% confidence interval [CI] 0.05-11.1%). The majority (54%) of MSM did not perceive that traumatic sexual and drug practices they were engaging in put them at risk for HCV. Unprotected sex often occurred under the influence of drugs or alcohol. Self-reported HCV risk and participation in several risk behaviors declined during the study. It was possible to collect frequent ALTs in a busy HIV clinic with 71% of total projected ALTs obtained and 88% of participants having at least one ALT during the 9-month follow-up period. All instances of ALT rise led to reflexive HCV RNA testing. Tracking quarterly ALT for elevation to systematically prompt HCV RNA testing before seroconversion is a promising approach to screen for acute HCV in a real-world HIV clinical setting.

Phase II open-label, safety, pharmacokinetic and efficacy study of 2-methoxyestradiol nanocrystal colloidal dispersion administered orally to patients with recurrent glioblastoma multiforme

2065

Background: 2-methoxyestradiol (2ME2) inhibits tumor cell proliferation and induces apoptosis by inhibiting microtubule polymerization and increasing reactive oxygen species-induced cell damage. In addition, 2ME2 downregulates HIF-1a at the posttranscriptional level and inhibits HIF-1a-mediated VEGF expression. Preclinical studies confirm significant in vitro and in vivo anti-glioma activity including tumor regression in combination with temozolomide. We therefore performed a single-center, phase 2 study to evaluate 2ME2 in recurrent glioblastoma multiforme (GBM) patients. Methods: Key eligibility include: adults with GBM at first or second recurrence; measurable disease; Karnofsky performance status = 70% and adequate organ function. 2ME2 was given orally 4 times/day at a dose of 1000mg for the first 11 patients and then escalated to 1500 mg for remaining patients. Patients are evaluated after every 28-day cycle. The primary efficacy endpoint is 6-month progression-free survival. Results: Sixteen patients (14 male) have been enrolled, including 7 at first recurrence and 9 at second recurrence. The median age is 52 years (range, 32–64 years). Thirty-five cycles have been administered to date. Grade II-IV, attributable toxicities include transaminase elevation (grade 3, n=3; grade 2, n=1); hypophosphatemia (grade 3, n=1); anorexia (grade 2, n=1) and rash (grade 2, n=1). Six patients (38%) have achieved stable disease including one minor response. PK studies revealed similar 2ME2 exposures to those achieved among solid tumor patients treated at the same dose level and no differences between GBM patients on or not on CYP3A-inducing anti-epileptic agents. Further accrual and follow-up is ongoing. Conclusions: Continuous daily 2ME2 dosing, administered as a monotherapeutic, is well tolerated and is associated with modest anti-tumor activity among recurrent GBM patients. Combination studies with temozolomide are underway.

No significant financial relationships to disclose.

Bevacizumab, a monoclonal antibody to vascular endothelial growth factor (VEGF), and irinotecan for treatment of malignant gliomas

1506

Background: The prognosis for recurrent malignant gliomas is poor, with a median survival <12 months, median progression-free survival <12 weeks and response rates <20%. Malignant gliomas have high concentrations of VEGF receptors, and the higher the VEGF receptor concentration, the worse the prognosis. Bevacizumab is a humanized IgG1 monoclonal antiblody to VEGF, which is synergistic with chemotherapy for most malignancies. Irinotecan is a topoisomerase 1 inhibitor, and has modest activity against recurrent malignant gliomas. Methods: We report a FDA approved phase II trial of bevacizumab and irinotecan for the treatment of recurrent malignant gliomas. 32 patients were enrolled, 23 with grade IV tumors (glioblastoma multiforme) and 9 with grade III tumors (anaplastic astrocytomas or oligodendrogliomas). All the patients had progressive disease and every patient had received prior radiation therapy and chemotherapy. Patients were treated every other week with bevacizumab 10 mg/kg and irinotecan 125 mg/m2 for patients not taking enzyme inducing anti-epileptic drugs or 340 mg/m2 for patients taking enzyme inducing anti-epileptic drugs. Results: The regimen was well tolerated with no CNS hemorrhages or >grade 1 systemic hemorrhages. Four patients were taken off study for thrombotic complications, 2 pulmonary emboli, 1 deep venous thrombus, and one thrombotic stroke. Two patients were discontinued secondary to grade 2 proteinuria and three were discontinued because they required non-neurosurgical surgery, appendectomy, repair of anal fissures and hip stabilization. The response rate was 63% (19 PRs and 1 CR). The median progression-free survival is 24 weeks. The median overall survival has not been reached, and exceeds 6 months. There have been ten deaths due to disease progression. Conclusions: The combination of bevacizumab and irinotecan is safe and one of the most active regimens against malignant gliomas.

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Tinzaparin prophylaxis against thromboembolic complications in brain tumor patients

1539

Background: Thromboembolic complications are common in brain tumor patients, contribute to the morbidity and mortality and complicate treatment. Twenty to 40% of brain tumor patients develop a deep venous thrombosis and/or pulmonary embolus during their course. Thromboembolic complications are the second leading cause of death in brain tumor patients. One of the low molecular weight heparins, tinzaparin, has increased factor Xa activity as opposed to thrombin inhibition, which may improve the therapeutic:toxicity ratio. Methods: We report a phase II trial of prophylactic tinzaparin for newly diagnosed brain tumor patients. Twenty-seven of the planned 40 patients have been accrued. Patients received daily tinzaparin at a fixed dose of 4500 IU subcutaneously beginning a minimum of 48 hours post-operatively and a maximum of 4 weeks post-operatively. Patients were scheduled to receive tinzaparin for 12 months. During chemotherapy cycles, the blood counts were monitored weekly. If the platelet count was <50,000, the tinzaparin was held until the platelets were >100,000. Results: One of the patients developed a grade 3 CNS hemorrhage, necessitating cessation of the tinzaparin, there have been no grade 4 or 5 CNS hemorrhages or treatment associated mortality. Also, there have been no ≥ grade 2 systemic hemorrhages. One patient developed a deep venous thrombosis while taking tinzaparin, and three patients developed thromboembolic complications while off tinzaparin secondary to thrombocytopenia. One patient was taken off study for increased liver function tests, possibly secondary to tinzaparin. The patients have taken the tinzaparin for 4–52 weeks, with a median of 18 weeks. Conclusions: Tinzaparin at a fixed prophylactic dose is safe and may decrease the incidence of thromboembolic complications in brain tumor patients. If the completed phase II study yields similar results, a phase III trial is warranted.

No significant financial relationships to disclose.

The afterglow and elliptical host galaxy of the short gamma-ray burst GRB 050724

Despite a rich phenomenology, gamma-ray bursts (GRBs) are divided into two classes based on their duration and spectral hardness--the long-soft and the short-hard bursts. The discovery of afterglow emission from long GRBs was a watershed event, pinpointing their origin to star-forming galaxies, and hence the death of massive stars, and indicating an energy release of about 10(51) erg. While theoretical arguments suggest that short GRBs are produced in the coalescence of binary compact objects (neutron stars or black holes), the progenitors, energetics and environments of these events remain elusive despite recent localizations. Here we report the discovery of the first radio afterglow from the short burst GRB 050724, which unambiguously associates it with an elliptical galaxy at a redshift z = 0.257. We show that the burst is powered by the same relativistic fireball mechanism as long GRBs, with the ejecta possibly collimated in jets, but that the total energy release is 10-1,000 times smaller. More importantly, the nature of the host galaxy demonstrates that short GRBs arise from an old (> 1 Gyr) stellar population, strengthening earlier suggestions and providing support for coalescing compact object binaries as the progenitors.

The afterglow of GRB 050709 and the nature of the short-hard gamma-ray bursts

The final chapter in the long-standing mystery of the gamma-ray bursts (GRBs) centres on the origin of the short-hard class of bursts, which are suspected on theoretical grounds to result from the coalescence of neutron-star or black-hole binary systems. Numerous searches for the afterglows of short-hard bursts have been made, galvanized by the revolution in our understanding of long-duration GRBs that followed the discovery in 1997 of their broadband (X-ray, optical and radio) afterglow emission. Here we present the discovery of the X-ray afterglow of a short-hard burst, GRB 050709, whose accurate position allows us to associate it unambiguously with a star-forming galaxy at redshift z = 0.160, and whose optical lightcurve definitively excludes a supernova association. Together with results from three other recent short-hard bursts, this suggests that short-hard bursts release much less energy than the long-duration GRBs. Models requiring young stellar populations, such as magnetars and collapsars, are ruled out, while coalescing degenerate binaries remain the most promising progenitor candidates.