Charity Njoku

Regression of glioma tumor growth in F98 and U87 rat glioma models by the Nitrone OKN-007

BACKGROUND Glioblastoma multiforme, a World Health Organization grade IV glioma, has a poor prognosis in humans despite current treatment options. Here, we present magnetic resonance imaging (MRI) data regarding the regression of aggressive rat F98 gliomas and human U87 glioma xenografts after treatment with the nitrone compound OKN-007, a disulfonyl derivative of α-phenyl-tert-butyl nitrone. METHODS MRI was used to assess tumor volumes in F98 and U87 gliomas, and bioluminescence imaging was used to measure tumor volumes in F98 gliomas encoded with the luciferase gene (F98(luc)). Immunohistochemistry was used to assess angiogenesis (vascular endothelial growth factor [VEGF] and microvessel density [MVD]), cell differentiation (carbonic anhydrase IX [CA-IX]), hypoxia (hypoxia-inducible factor-1α [HIF-1α]), cell proliferation (glucose transporter 1 [Glut-1] and MIB-1), proliferation index, and apoptosis (cleaved caspase 3) markers in F98 gliomas. VEGF, CA-IX, Glut-1, HIF-1α, and cleaved caspase 3 were assessed in U87 gliomas. RESULTS Animal survival was found to be significantly increased (P < .001 for F98, P < .01 for U87) in the group that received OKN-007 treatment compared with the untreated groups. After MRI detection of F98 gliomas, OKN-007, administered orally, was found to decrease tumor growth (P < .05). U87 glioma volumes were found to significantly decrease (P < .05) after OKN-007 treatment, compared with untreated animals. OKN-007 administration resulted in significant decreases in tumor hypoxia (HIF-1α [P < .05] in both F98 and U87), angiogenesis (MVD [P < .05], but not VEGF, in F98 or U87), and cell proliferation (Glut-1 [P < .05 in F98, P < .01 in U87] and MIB-1 [P < .01] in F98) and caused a significant increase in apoptosis (cleaved caspase 3 [P < .001 in F98, P < .05 in U87]), compared with untreated animals. CONCLUSIONS OKN-007 may be considered as a promising therapeutic addition or alternative for the treatment of aggressive human gliomas.

Utility of nuclear magnetic resonance spectroscopy for pancreatic cancer studies

Objectives The aims of this study were (1) to determine nuclear magnetic resonance spectroscopic characteristics and metabolite profiles of serum samples from patients with pancreatic cancer compared with noncancerous control samples and (2) to ascertain if the accuracy of metabolite identification by 1D spectra can be improved upon by confirmation of spin-system assignment using more sophisticated experiments. Methods Nuclear magnetic resonance spectra, including 1D, total correlation spectroscopy, and heteronuclear multiple/single quantum coherence, were obtained from serum samples from patients with pancreatic cancer and control subjects and used to determine serum levels of a range of metabolites. Results The data show that total choline (P = 0.03), taurine (P = 0.03), and glucose plus triglycerides (P = 0.01) are significantly higher in cancer versus control samples. Also detected were species that could not be individually identified and that were designated UCM (unresolved complex matter). Levels of UCM are significantly higher in subjects with cancer, being almost double those of control samples. Conclusions Although metabolites such as lactate, taurine, glucose, choline, and triglycerides can be determined from 1D spectra, accuracy is improved by confirmation of spin-system assignment with total correlation spectroscopy and heteronuclear multiple/single quantum coherence spectral analysis. In addition, we introduce a new metric, UCM, which is at higher concentrations in cancer compared with control samples.

Motif mimetic of epsin perturbs tumor growth and metastasis

Tumor angiogenesis is critical for cancer progression. In multiple murine models, endothelium-specific epsin deficiency abrogates tumor progression by shifting the balance of VEGFR2 signaling toward uncontrolled tumor angiogenesis, resulting in dysfunctional tumor vasculature. Here, we designed a tumor endothelium-targeting chimeric peptide (UPI) for the purpose of inhibiting endogenous tumor endothelial epsins by competitively binding activated VEGFR2. We determined that the UPI peptide specifically targets tumor endothelial VEGFR2 through an unconventional binding mechanism that is driven by unique residues present only in the epsin ubiquitin-interacting motif (UIM) and the VEGFR2 kinase domain. In murine models of neoangiogenesis, UPI peptide increased VEGF-driven angiogenesis and neovascularization but spared quiescent vascular beds. Further, in tumor-bearing mice, UPI peptide markedly impaired functional tumor angiogenesis, tumor growth, and metastasis, resulting in a notable increase in survival. Coadministration of UPI peptide with cytotoxic chemotherapeutics further sustained tumor inhibition. Equipped with localized tumor endothelium-specific targeting, our UPI peptide provides potential for an effective and alternative cancer therapy.

OKN-007 decreases free radical levels in a preclinical F98 rat glioma model.

Free radicals are associated with glioma tumors. Here, we report on the ability of an anticancer nitrone compound, OKN-007 [Oklahoma Nitrone 007; a disulfonyl derivative of α-phenyl-tert-butyl nitrone (PBN)] to decrease free radical levels in F98 rat gliomas using combined molecular magnetic resonance imaging (mMRI) and immunospin-trapping (IST) methodologies. Free radicals are trapped with the spin-trapping agent, 5,5-dimethyl-1-pyrroline N-oxide (DMPO), to form DMPO macromolecule radical adducts, and then further tagged by immunospin trapping by an antibody against DMPO adducts. In this study, we combined mMRI with a biotin-Gd-DTPA-albumin-based contrast agent for signal detection with the specificity of an antibody for DMPO nitrone adducts (anti-DMPO probe), to detect in vivo free radicals in OKN-007-treated rat F98 gliomas. OKN-007 was found to significantly decrease (P < 0.05) free radical levels detected with an anti-DMPO probe in treated animals compared to untreated rats. Immunoelectron microscopy was used with gold-labeled antibiotin to detect the anti-DMPO probe within the plasma membrane of F98 tumor cells from rats administered anti-DMPO in vivo. OKN-007 was also found to decrease nuclear factor erythroid 2-related factor 2, inducible nitric oxide synthase, 3-nitrotyrosine, and malondialdehyde in ex vivo F98 glioma tissues via immunohistochemistry, as well as decrease 3-nitrotyrosine and malondialdehyde adducts in vitro in F98 cells via ELISA. The results indicate that OKN-007 effectively decreases free radicals associated with glioma tumor growth. Furthermore, this method can potentially be applied toward other types of cancers for the in vivo detection of macromolecular free radicals and the assessment of antioxidants.

ELTD1, an effective anti-angiogenic target for gliomas: Preclinical assessment in mouse GL261 and human G55 xenograft glioma models

Background Despite current therapies, glioblastoma is a devastating cancer, and validation of effective biomarkers for it will enable better diagnosis and therapeutic intervention for this disease. We recently discovered a new biomarker for high-grade gliomas, ELTD1 (epidermal growth factor, latrophilin, and 7 transmembrane domain-containing protein 1 on chromosome 1) via bioinformatics, and validated that ELTD1 protein levels are significantly higher in human and rodent gliomas. The focus of this study was to assess the effect on tumor growth of an antibody against ELTD1 in orthotopic, GL261, and G55 xenograft glioma models. Methods The effect of anti-ELTD1 antibody therapy was assessed by animal survival, MRI measured tumor volumes, MR angiography, MR perfusion imaging, and immunohistochemistry (IHC) characterization of microvessel density in mouse glioma models. Comparative treatments included anti-vascular endothelial growth factor (VEGF) and anti-c-Met antibody therapies, compared with untreated controls. Results Tumor volume and survival data in this study show that antibodies against ELTD1 inhibit glioma growth just as effectively or even more so compared with other therapeutic targets studied, including anti-VEGF antibody therapy. Untreated GL261 or G55 tumors were found to have significantly higher ELTD1 levels (IHC) compared with contralateral normal brain. The anti-angiogenic effect of ELTD1 antibody therapy was observed in assessment of microvessel density, as well as from MR angiography and perfusion measurements, which indicated that anti-ELTD1 antibody therapy significantly decreased vascularization compared with untreated controls. Conclusions Either as a single therapy or in conjunction with other therapeutic approaches, anti-ELTD1 antibodies could be a valuable new clinical anti-angiogenic therapeutic for high-grade gliomas.

OKN-007 decreases tumor necrosis and tumor cell proliferation and increases apoptosis in a preclinical F98 rat glioma model

Glioblastoma is a malignant World Health Organization (WHO) grade IV glioma with a poor prognosis in humans. New therapeutics are desperately required. The nitrone OKN‐007 (2,4‐disulfophenyl‐PBN) has demonstrated effective anti‐glioma properties in several rodent models and is currently being used as a clinical investigational drug for recurrent gliomas. We assessed the regional effects of OKN‐007 in the tumor necrotic core and non‐necrotic tumor parenchyma.

Gestational hypoxia disrupts the neonatal leptin surge and programs hyperphagia and obesity in male offspring in the Sprague-Dawley rat

The effect of gestational hypoxia on the neonatal leptin surge, development of hypothalamic arcuate nuclei (ARH) projections and appetite that could contribute to the programming of offspring obesity is lacking. We examined the effect of 12% O2 from gestational days 15–19 in the Sprague-Dawley rat on post-weaning appetite, fat deposition by MRI, adipose tissue cytokine expression, the neonatal leptin surge, ARH response to exogenous leptin, and αMSH projections to the paraventricular nucleus (PVN) in response to a high fat (HFD) or control diet (CD) in male offspring. Normoxia (NMX) and Hypoxia (HPX) offspring exhibited increased food intake when fed a HFD from 5–8 weeks post-birth; HPX offspring on the CD had increased food intake from weeks 5–7 vs. NMX offspring on a CD. HPX offspring on a HFD remained hyperphagic through 23 weeks. Body weight were the same between offspring from HPX vs. NMX dams from 4–12 weeks of age fed a CD or HFD. By 14–23 weeks of age, HPX offspring fed the CD or HFD as well as male NMX offspring fed the HFD were heavier vs. NMX offspring fed the CD. HPX offspring fed a CD exhibited increased abdominal adiposity (MRI) that was amplified by a HFD. HPX offspring fed a HFD exhibited the highest abdominal fat cytokine expression. HPX male offspring had higher plasma leptin from postnatal day (PN) 6 through 14 vs. NMX pups. HPX offspring exhibited increased basal c-Fos labeled cells in the ARH vs. NMX pups on PN16. Leptin increased c-Fos staining in the ARH in NMX but not HPX offspring at PN16. HPX offspring had fewer αMSH fibers in the PVN vs. NMX offspring on PN16. In conclusion, gestational hypoxia impacts the developing ARH resulting in hyperphagia contributing to adult obesity on a control diet and exacerbated by a HFD.

Abstract 4307: MRI characterization of OKN-007 efficacy in a preclinical pediatric glioma model

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA High grade gliomas (HGG) are common primary CNS tumors in children. Here, we report the preliminary data about the efficacy of a nitrone compound, OKN-007 [Oklahoma Nitrone 007; a disulfonyl derivative of α-phenyl-tertbutyl nitrone (PBN)], in a preclinical pediatric HGG model (IC3752GBMV) by using Magnetic Resonance Imaging (MRI). The right cerebrum of eight week old male athymic nude mice was injected with IC3752GBMV pediatric HGG cells. The animals were divided in 2 groups: (A) untreated and (B) treated with OKN-007, which was given continuously (0.025% w/v) by drinking water after the tumors have reached volumes of 10-20 mm3. MRI was performed using a 7 Tesla Bruker BioSpin system and repeated weekly to access the tumor volumes. Diffusion-Weighted Imaging (DWI), Perfusion-Weighted Imaging (PWI), and Magnetic Resonance Spectroscopy (MRS) techniques were performed in both groups to evaluate the efficacy of OKN-007 in the pediatric cell lineage IC3752GBMV. The results of this study are preliminary and we are reporting here the data of only one animal of each group. For the OKN-007 treated group (88.58 mm3), the tumor volume was decreased when compared to the untreated group (139.3 mm3) at the last day point (day 51). Based on DWI, the ADC (Apparent Diffusion Coefficient) values (1x10-4 mm2/s) of the tumors normalized to contralateral brain were 0.949 for Group A, and 1.087 for Group B. The tumor of the OKN-007 treated animal had increased perfusion ratio (tumor/contralateral side of the brain) of 0.58 in comparison to the untreated control ratio of -5.28. The MRS data showed that the lipid (methylene)-to-creatine ratio was decreased in the pediatric glioma treated with OKN-007 versus the untreated tumor (14.89 and 23.75 respectively). This is the first report of evaluation of anti-cancer therapy efficacy of OKN-007 in a pediatric xenograft model by using DWI, PWI, and MRS techniques. Based on our preliminary results, DWI, PWI and MRS may provide some information useful in evaluating OKN-007 anti-cancer therapeutic response in pediatric HGG. OKN-007 decreased the tumor volume, and increased tumor perfusion rates, similar to what we found in a rat glioma model1. OKN-007 may also affect tumor metabolism in this pediatric HGG model, which was denoted by changes in the lipid (methylene)-to-creatine ratio. Similar results have been described previously in several different glioma models by our group2. In conclusion, the pediatric HGG IC3752GBMV model may facilitate biological studies and preclinical drug screenings for pediatric HGG. Furthermore, OKN-007 may be considered as a potential alternate and new therapy for pediatric HGG. This preliminary data will need to be repeated to confirm our findings. REFERENCES 1. Garteiser P. et al (2010). J Magn Reson Imaging. 31: 796-806. 2. Doblas S et al (2012). NMR Biomed.25:685-94. Note: This abstract was not presented at the meeting. Citation Format: Patricia Coutinho de Souza, Nataliya Smith, Charity Njoku, Debra Saunders, Krithika Balasubramanian, Rene Y. McNall, Xiao-Nan Li, Rheal A. Towner. MRI characterization of OKN-007 efficacy in a preclinical pediatric glioma model. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4307. doi:10.1158/1538-7445.AM2014-4307

Abstract 2682: ELTD1 as a target for anti-cancer therapy in rodent gliomas

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Despite current therapies, glioblastoma multiforme (GBM) is a devastating cancer with a very poor prognosis. Specific protein biomarkers for GBM enable not only new prognostic avenues to tailor treatment, but valuable therapeutic targets to interfere with GBM growth. We recently discovered a new biomarker for high-grade gliomas, ELTD1 (epidermal growth factor, latrophilin, and 7 transmembrane domain-containing protein 1 on chromosome 1), via a novel bioinformatics approach, GAMMA (Global microarray meta-analysis). ELTD1 was found to be significantly higher (p<0.05) in high-grade gliomas (50 patients) compared with low-grade gliomas (21 patients). ELTD1 gene expression was found to be associated with tumor grade, survival across grade, and an increase in the mesenchymal subtype. From our previous results we hypothesized that ELTD1 may be a potential therapeutic target in high-grade gliomas. We tested the hypothesis in an orthotopic GL261 mouse glioma model in animals treated with an anrti-ELTD1 antibody, compared to those that were treated with an anti-VEGF antibody or an anti-c-Met antibody, and untreated tumors. Tumor volumes were measured by morphological magnetic resonance imaging (MRI). Our data in orthotopic GL261 glioma-bearing mice shows that injection of anti-ELTD1 antibodies lead to a significant decrease in tumor volumes (p<0.0001) and a significant increase in animal survival (p<0.05), superior to that achieved by a mouse anti-VEGF antibody or an antibody against c-Met, when compared to untreated mice. Tumor volumes were obtained at various time-points, and compared at 21 days following intracerebral implantation of GL261 cells in male C57BL6 mice. These tumor volumes at 21 days were 86.03+/-41.54 mm3 for untreated mice (n=5); 13.04+/-5.35 mm3 for anti-ELTD1 treated mice (n=5); 33.16+/-12.48 mm3 for anti-VEGF treated mice (n=4); and 28.49+/-11.11 mm3 for anti-c-Met treated mice (n=5). The mean days of survival for untreated, ELTD1, VEGF or c-Met treatment groups were 23.8+/-1.79, 28.2+/-2.39, 27+/-1.15 or 27+/-1.87 days, respectively. These pre-clinical results indicate that an additional therapy in the form of an anti-ELTD1 antibody either as a sole agent or in combination with current or new therapies could potentially provide high-grade glioma patients with a better prognostic outcome. Citation Format: Rheal A. Towner, Richard Pody, Nataliya Smith, Debra Saunders, Charity Njoku, Jonathan D. Wren. ELTD1 as a target for anti-cancer therapy in rodent gliomas. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2682. doi:10.1158/1538-7445.AM2014-2682