GBM radiosensitizers: dead in the water…or just the beginning?

The finding that most GBMs recur either near or within the primary site after radiotherapy has fueled great interest in the development of radiosensitizers to enhance local control. Unfortunately, decades of clinical trials testing a wide range of novel therapeutic approaches have failed to yield any clinically viable radiosensitizers. However, many of  the previous radiosensitizing strategies were not based on clear pre-clinical evidence, and in many cases blood-barrier penetration was not considered. Furthermore, DNA repair inhibitors have only recenly arrived in the clinic, and likely represent potent agents for glioma radiosensitization. Here, we present recent progress in the use of small molecule DNA damage response inhibitors as GBM radiosensitizers. In addition, we discuss the latest progress in targeting hypoxia and oxidative stress for GBM radiosensitization

Noninvasive measurement of tissue blood oxygenation with Cerenkov imaging during therapeutic radiation delivery

Tumor tissue oxygenation significantly affects the outcome of radiotherapy. Real-time monitoring of tumor hypoxia is highly desirable for effective radiotherapy, and is the basis for improved treatment because hypoxic tumor cells are more resistant to radiation damage than fully oxygenated cells. We propose to use Cerenkov imaging to monitor tumor hypoxia by means of tissue blood oxygenation without the need for any exogenous contrast agent. Using a rodent hypoxia model, we demonstrate that Cerenkov imaging can be used as a noninvasive and noncontact method to measure tissue blood oxygenation level during radiation delivery. The data from Cerenkov imaging were validated using near infrared spectrometry methods. The results demonstrate the feasibility of using Cerenkov imaging to monitor tumor hypoxia during therapeutic radiation delivery

SplicerAV: a tool for mining microarray expression data for changes in RNA processing

<p>Abstract</p> <p>Background</p> <p>Over the past two decades more than fifty thousand unique clinical and biological samples have been assayed using the Affymetrix HG-U133 and HG-U95 GeneChip microarray platforms. This substantial repository has been used extensively to characterize changes in gene expression between biological samples, but has not been previously mined <it>en masse </it>for changes in mRNA processing. We explored the possibility of using HG-U133 microarray data to identify changes in alternative mRNA processing in several available archival datasets.</p> <p>Results</p> <p>Data from these and other gene expression microarrays can now be mined for changes in transcript isoform abundance using a program described here, SplicerAV. Using <it>in vivo </it>and <it>in vitro </it>breast cancer microarray datasets, SplicerAV was able to perform both gene and isoform specific expression profiling within the same microarray dataset. Our reanalysis of Affymetrix U133 plus 2.0 data generated by <it>in vitro </it>over-expression of HRAS, E2F3, beta-catenin (CTNNB1), SRC, and MYC identified several hundred oncogene-induced mRNA isoform changes, one of which recognized a previously unknown mechanism of <it>EGFR </it>family activation. Using clinical data, SplicerAV predicted 241 isoform changes between low and high grade breast tumors; with changes enriched among genes coding for guanyl-nucleotide exchange factors, metalloprotease inhibitors, and mRNA processing factors. Isoform changes in 15 genes were associated with aggressive cancer across the three breast cancer datasets.</p> <p>Conclusions</p> <p>Using SplicerAV, we identified several hundred previously uncharacterized isoform changes induced by <it>in vitro </it>oncogene over-expression and revealed a previously unknown mechanism of EGFR activation in human mammary epithelial cells. We analyzed Affymetrix GeneChip data from over 400 human breast tumors in three independent studies, making this the largest clinical dataset analyzed for <it>en masse </it>changes in alternative mRNA processing. The capacity to detect RNA isoform changes in archival microarray data using SplicerAV allowed us to carry out the first analysis of isoform specific mRNA changes directly associated with cancer survival.</p

A pilot clinical trial of intravesical mitomycin-C and external deep pelvic hyperthermia for non-muscle-invasive bladder cancer.

PURPOSE: This paper aims to evaluate the safety and heating efficiency of external deep pelvic hyperthermia combined with intravesical mitomycin C (MMC) as a novel therapy for non-muscle-invasive bladder cancer (NMIBC). MATERIALS AND METHODS: We enrolled subjects with bacillus Calmette-Guérin (BCG) refractory NMIBC to an early phase clinical trial of external deep pelvic hyperthermia (using a BSD-2000 device) combined with MMC. Bladders were heated to 42 °C for 1 h during intravesical MMC treatment. Treatments were given weekly for 6 weeks, then monthly for 4 months. Heating parameters, treatment toxicity, and clinical outcomes were systematically measured. RESULTS: Fifteen patients were enrolled on the clinical trial. Median age was 66 years and 87% were male. Median European Organisation for Research and Treatment of Cancer (EORTC) recurrence and progression scores were 6 and 8, respectively. The full treatment course was attained in 73% of subjects. Effective bladder heating was possible in all but one patient who could not tolerate the supine position due to lung disease. Adverse events were all minor (grade 2 or less) and no systemic toxicity was observed. The most common adverse effects were Foley catheter pain (40%), abdominal discomfort (33%), chemical cystitis symptoms (27%), and abdominal skin swelling (27%). With a median follow-up of 3.18 years, 67% experienced another bladder cancer recurrence (none were muscle invasive) and 13% experienced an upper tract recurrence. CONCLUSIONS: External deep pelvic hyperthermia using the BSD-2000 device is a safe and reproducible method of heating the bladder in patients undergoing intravesical MMC. The efficacy of this treatment modality should be explored further in clinical trials

Measuring Tumor Cycling Hypoxia and Angiogenesis Using a Side-firing Fiber Optic Probe

Hypoxia and angiogenesis can significantly influence the efficacy of cancer therapy and the behavior of surviving tumor cells. There is a growing demand for technologies to measure tumor hypoxia and angiogenesis temporally in vivo to enable advances in drug development and optimization. This paper reports the use of frequency-domain photon migration with a side-firing probe to quantify tumor oxygenation and hemoglobin concentrations in nude rats bearing human head/neck tumors administered with carbogen gas, cycling hypoxic gas or just room air. Significant increase (with carbogen gas breathing) or decrease (with hypoxic gas breathing) in tumor oxygenation was observed. The trend in tumor oxygenation during forced cycling hypoxia (CH) followed that of the blood oxygenation measured with a pulse oximeter. Natural CH was also observed in rats under room air. The studies demonstrated the potential of the technology for longitudinal monitoring of tumor CH during tumor growth or in response to therapy

Neisseria oralis sp. nov., isolated from healthy gingival plaque and clinical samples

A polyphasic analysis was undertaken of seven independent isolates of Gram-negative cocci collected from pathological clinical samples from New York, Louisiana, Florida and Illinois and healthy subgingival plaque from a patient in Virginia, USA. The 16S rRNA gene sequence similarity among these isolates was 99.7–100 %, and the closest species with a validly published name was Neisseria lactamica (96.9 % similarity to the type strain). DNA–DNA hybridization confirmed that these isolates are of the same species and are distinct from their nearest phylogenetic neighbour, N. lactamica. Phylogenetic analysis of 16S and 23S rRNA gene sequences indicated that the novel species belongs in the genus Neisseria. The predominant cellular fatty acids were C16 : 0, summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH) and C18 : 1ω7c. The cellular fatty acid profile, together with other phenotypic characters, further supports the inclusion of the novel species in the genus Neisseria. The name Neisseria oralis sp. nov. (type strain 6332T = DSM 25276T = LMG 26725T) is proposed

Pleiotropic effects of HIF-1 blockade on tumor radiosensitivity

SummaryWe have previously shown that radiation increases HIF-1 activity in tumors, causing significant radioprotection of the tumor vasculature. The impact that HIF-1 activation has on overall tumor radiosensitivity, however, is unknown. We reveal here that HIF-1 plays an important role in determining tumor radioresponsiveness through regulating four distinct processes. By promoting ATP metabolism, proliferation, and p53 activation, HIF-1 has a radiosensitizing effect on tumors. Through stimulating endothelial cell survival, HIF-1 promotes tumor radioresistance. As a result, the net effect of HIF-1 blockade on tumor radioresponsiveness is highly dependent on treatment sequencing, with “radiation first” strategies being significantly more effective than the alternative. These data provide a strong rationale for pursuing sequence-specific combinations of HIF-1 blockade and conventional therapeutics

Structural Adaptation and Heterogeneity of Normal and Tumor Microvascular Networks

Relative to normal tissues, tumor microcirculation exhibits high structural and functional heterogeneity leading to hypoxic regions and impairing treatment efficacy. Here, computational simulations of blood vessel structural adaptation are used to explore the hypothesis that abnormal adaptive responses to local hemodynamic and metabolic stimuli contribute to aberrant morphological and hemodynamic characteristics of tumor microcirculation. Topology, vascular diameter, length, and red blood cell velocity of normal mesenteric and tumor vascular networks were recorded by intravital microscopy. Computational models were used to estimate hemodynamics and oxygen distribution and to simulate vascular diameter adaptation in response to hemodynamic, metabolic and conducted stimuli. The assumed sensitivity to hemodynamic and conducted signals, the vascular growth tendency, and the random variability of vascular responses were altered to simulate ‘normal’ and ‘tumor’ adaptation modes. The heterogeneous properties of vascular networks were characterized by diameter mismatch at vascular branch points (d3var) and deficit of oxygen delivery relative to demand (O2def). In the tumor, d3var and O2def were higher (0.404 and 0.182) than in normal networks (0.278 and 0.099). Simulated remodeling of the tumor network with ‘normal’ parameters gave low values (0.288 and 0.099). Conversely, normal networks attained tumor-like characteristics (0.41 and 0.179) upon adaptation with ‘tumor’ parameters, including low conducted sensitivity, increased growth tendency, and elevated random biological variability. It is concluded that the deviant properties of tumor microcirculation may result largely from defective structural adaptation, including strongly reduced responses to conducted stimuli

Thermal dosimetry characteristics of deep regional heating of non-muscle invasive bladder cancer.

PURPOSE: The aim of this paper is to report thermal dosimetry characteristics of external deep regional pelvic hyperthermia combined with intravesical mitomycin C (MMC) for treating bladder cancer following transurethral resection of bladder tumour, and to use thermal data to evaluate reliability of delivering the prescribed hyperthermia dose to bladder tissue. MATERIALS AND METHODS: A total of 14 patients were treated with MMC and deep regional hyperthermia (BSD-2000, Sigma Ellipse or Sigma 60). The hyperthermia objective was 42° ± 2 °C to bladder tissue for ≥40 min per treatment. Temperatures were monitored with thermistor probes and recorded values were used to calculate thermal dose and evaluate treatment. Anatomical characteristics were examined for possible correlations with heating. RESULTS: Combined with BSD-2000 standard treatment planning and patient feedback, real-time temperature monitoring allowed thermal steering of heat sufficient to attain the prescribed thermal dose to bladder tissue within patient tolerance in 91.6% of treatments. Mean treatment time for bladder tissue \u3e40 °C was 61.9 ± 11.4 min and mean thermal dose was 21.3 ± 16.5 CEM43. Average thermal doses obtained in normal tissues were 1.6 ± 1.2 CEM43 for the rectum and 0.8 ± 1.3 CEM43 in superficial normal tissues. No significant correlation was seen between patient anatomical characteristics and thermal dose achieved in bladder tissue. CONCLUSIONS: This study demonstrates that a hyperthermia prescription of 42° ± 2 °C for 40-60 min can be delivered safely to bladder tissue with external radiofrequency phased array applicators for a typical range of patient sizes. Using the available thermometry and treatment planning, the BSD-2000 hyperthermia system was shown to be an effective method of focusing heat regionally around the bladder with good patient tolerance

Endothelial cell-surface tissue transglutaminase inhibits neutrophil adhesion by binding and releasing nitric oxide

Nitric oxide (NO) produced by endothelial cells in response to cytokines displays anti-inflammatory activity by preventing the adherence, migration and activation of neutrophils. The molecular mechanism by which NO operates at the blood-endothelium interface to exert anti-inflammatory properties is largely unknown. Here we show that on endothelial surfaces, NO is associated with the sulfhydryl-rich protein tissue transglutaminase (TG2), thereby endowing the membrane surfaces with anti-inflammatory properties. We find that tumor necrosis factor-α-stimulated neutrophil adherence is opposed by TG2 molecules that are bound to the endothelial surface. Alkylation of cysteine residues in TG2 or inhibition of endothelial NO synthesis renders the surface-bound TG2 inactive, whereas specific, high affinity binding of S-nitrosylated TG2 (SNO-TG2) to endothelial surfaces restores the anti-inflammatory properties of the endothelium, and reconstitutes the activity of endothelial-derived NO. We also show that SNO-TG2 is present in healthy tissues and that it forms on the membranes of shear-activated endothelial cells. Thus, the anti-inflammatory mechanism that prevents neutrophils from adhering to endothelial cells is identified with TG2 S-nitrosylation at the endothelial cell-blood interface