RONC-20. RECURRENT HIGH-GRADE ASTROBLASTOMA TREATED WITH STEREOTACTIC RADIOTHERAPY

INTRODUCTION

Astroblastoma is a rare, mostly supratentorial glial tumor, occurring predominantly in children and young adults. However, treatment strategies have not yet been established for this rare disease.

CASE PRESENTATION

A 6-year-old male presented with headache and nausea. CT and MR imaging revealed a left frontal mass lesion with slight edema and macrocalcifications. Gross tumor resection was performed. Histological examination found neoplastic cells with astroblastic characteristics, and a striking perivascular array of pseudorosettes. The final diagnosis was high-grade astroblastoma. MR imaging 13 months after surgery suggested local recurrence and enlargement was found 3 months later. Stereotactic radiotherapy (SRT) was performed. MR imaging after SRT showed enhanced cyst formation around the tumor bed, suggesting tumor recurrence. However, ¹¹C-methionine PET revealed radiation necrosis. The last follow-up MR imaging 15 months after SRT showed no further recurrence.

CONCLUSION

Astroblastoma is rare, so no optimal management is known. SRT may be effective to treat recurrent astroblastomas. ¹¹C-methionine PET/CT is useful for the differentiation from radiation necrosis.

Targeting CD146 using folic acid-conjugated nanoparticles and suppression of tumor growth in a mouse glioma model

OBJECTIVE

Glioma stem cells (GSCs) are responsible for tumor initiation, therapeutic resistance, and recurrence. CD146 is mainly expressed in dividing GSCs and regulates cell cycle progression. However, the evaluation of the efficacy of targeted therapy against CD146 in vivo remains to be investigated. In this study, the authors aimed to develop gene therapy targeting GSCs using chitosan oligosaccharide lactate (COL) nanoparticles (NPs) conjugated with folic acid-polyethylene glycol (FA-PEG-COL NPs) for in vitro and in vivo delivery of CD146 small-interfering RNA (siCD146) and to determine the effect of CD146 knockdown on tumor growth.

METHODS

To examine the uptake of NPs by tumor cells, immunofluorescence staining, flow cytometry, and in vivo imaging were performed. The knockdown effect of siCD146 was measured by western blot and water-soluble tetrazolium salt-8 assay in mouse glioma cells. The efficacy of siRNA therapy-targeted GSCs was evaluated by monitoring tumor growth through in vivo imaging and histological analysis.

RESULTS

In vivo accumulation of the FA-PEG-COL NPs in subcutaneous and intracranial gliomas following NP administration via a mouse tail vein was observed. Additionally, in vitro delivery of siCD146 ionically cross-linked NPs, reduced CD146 levels, and suppressed growth in the glioma tumor sphere. Evaluation of the in vivo therapeutic effects of siCD146-cross-linked NPs in a mouse glioma model revealed significant suppression of intracranial tumor growth, with complete removal of the tumor observed in some mice on histological examination. Furthermore, delivery of siCD146 significantly reduced the Ki-67 index in residual tumor tissues relative to that in control mice.

CONCLUSIONS

CD146 is a potential therapeutic target, and folic acid-conjugated NPs delivering siRNA may facilitate gene therapy in malignant gliomas.

Zinc-aggravated M1 microglia regulate astrocytic engulfment via P2×7 receptors

BACKGROUND

Glial cells such as astrocytes and microglia play an important role in the central nervous system via communication between these glial cells. Activated microglia can exhibit either the inflammatory M1 phenotype or the anti-inflammatory M2 phenotype, which influences astrocytic neuroprotective functions, including engulfment of cell debris. Recently, extracellular zinc has been shown to promote the inflammatory M1 phenotype in microglia through intracellular zinc accumulation and reactive oxygen species (ROS) generation.

PURPOSE

Here, we investigated whether the zinc-enhanced inflammatory M1 phenotype of microglia affects the astrocytic engulfing activity.

METHODS

Engulfing activity was assessed in astrocytes treated with microglial-conditioned medium (MCM) from lipopolysaccharide (LPS)-activated or from ZnCl2-pretreated LPS-activated M1 microglia. The effect of zinc on microglia phenotype was also validated using the zinc chelator N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) and the ROS scavenger Trolox.

RESULTS

Although treatment of astrocytes with LPS showed no significant effect on the engulfing activity, MCM from LPS-induced M1 microglia increased the beads uptake by astrocytes. This increased uptake activity was suppressed when MCM from LPS-induced M1 microglia pretreated with ZnCl2 was applied to astrocytes, which was further abolished by the intracellular zinc chelator TPEN and the ROS scavenger Trolox. In addition, expression of P2×7 receptors (P2×7R) was increased in astrocytes treated with MCM derived from M1 microglia but not in the M1 microglia pretreated with ZnCl2.

CONCLUSION

These findings suggest that zinc pre-treatment abolishes the ability of LPS-induced M1 microglia to increase the engulfing activity in astrocytes via alteration of astrocytic P2×7R.

IMT-03 CLINICAL TRIAL FOR NEWLY DIAGNOSED MALIGNANT GLIOMA WITH WT1-W10 VACCINATION

OBJECT

Wilms’ tumor 1 (WT1) peptide vaccination is considered a potentially effective therapy against malignant glioma. We conducted a Phase I/II study to investigate the safety and feasibility of novel WT1 peptide (W10) vaccination therapy for patients with newly diagnosed malignant glioma.

METHODS

WT1 vaccination therapy was performed for patients with malignant glioma who have undergone concurrent radiotherapy and temozolomide therapy. A mixture of WT1 peptide with inactivated pertussis whole cell vaccine was injected intradermally once a week for at least 12 weeks.

RESULTS

Twenty-seven patients (12 men, 15 women; median 65 years) with the following tumors were enrolled: WHO grade IV (15), WHO grade III (12). PFS and OS of glioblastoma cases were 12.7 months 21.9 months, respectively. PFS of the MGMT unmethylated group was shorter than the methylated group. Interestingly enough, overall survival in the MGMT unmethylated group was not significantly different from the methylated group. Analysis of recurrent cases after immunotherapy showed decreased expression of WT1 antigen and increased Treg. They were suggested as a cause of treatment resistance. No serious adverse events were observed except for Grade 1 erythema at the injection sites.

CONCLUSIONS

This study of a novel WT1 vaccination therapy demonstrated safety and feasibility in the management of newly diagnosed malignant gliomas.

The inhibitory role of intracellular free zinc in the regulation of Arg-1 expression in interleukin-4-induced activation of M2 microglia

Microglia, the resident immune cells of the central nervous system, can display a pro-inflammatory M1 phenotype or an anti-inflammatory M2 phenotype. Arginase (Arg)-1 expressed in interleukin-4 (IL-4)-induced M2 microglia reduces nitric oxide (NO) production by competing with inducible NO synthase for l-arginine, which contributes to the attenuation of brain inflammation. Although previous studies have indicated that brain zinc promotes M1 activation, the effect of zinc on M2 microglial activation remains to be determined. In the present study, murine primary microglia treated with 10 ng mL^-1 IL-4 exhibited increased Arg-1 mRNA expression and levels of intracellular free zinc. Chelation of this increased intracellular free zinc by the cell permeable zinc chelator N,N,N',N'-tetrakis-(2-pyridylmethyl)ethylenediamine (TPEN) aggravated the IL-4-induced mRNA expression and enzymatic activity of Arg-1. However, the cell impermeable zinc chelator CaEDTA had no effect on Arg-1 expression or cytosolic levels of free zinc in IL-4-induced M2-polarized microglia. Furthermore, treatment with IL-4 resulted in upregulation of phagocytic activity in microglia, while administration of TPEN abolished IL-4-induced phagocytic activity. Moreover, this effect was reversed vial-arginine supplementation. These findings suggest that IL-4 induces an increase in intracellular free zinc in microglia, which may act as a negative regulator of IL-4-induced Arg-1 expression, and that such negative regulation is essential for microglial phagocytic activity.

Stimulation of brain nicotinic acetylcholine receptors activates adrenomedullary outflow via brain inducible NO synthase-mediated S-nitrosylation

BACKGROUND AND PURPOSE

We have demonstrated that i.c.v.-administered (±)-epibatidine, a nicotinic ACh receptor (nAChR) agonist, induced secretion of noradrenaline and adrenaline (catecholamines) from the rat adrenal medulla with dihydro-β-erythroidin (an α4β2 nAChR antagonist)-sensitive brain mechanisms. Here, we examined central mechanisms for the (±)-epibatidine-induced responses, focusing on brain NOS and NO-mediated mechanisms, soluble GC (sGC) and protein S-nitrosylation (a posttranslational modification of protein cysteine thiol groups), in urethane-anaesthetized (1.0 g·kg^-1 , i.p.) male Wistar rats.

EXPERIMENTAL APPROACH

(±)-Epibatidine was i.c.v. treated after i.c.v. pretreatment with each inhibitor described below. Then, plasma catecholamines were measured electrochemically after HPLC. Immunoreactivity of S-nitrosylated cysteine (SNO-Cys) in α4 nAChR subunit (α4)-positive spinally projecting neurones in the rat hypothalamic paraventricular nucleus (PVN, a regulatory centre of adrenomedullary outflow) after i.c.v. (±)-epibatidine administration was also investigated.

KEY RESULTS

(±)-Epibatidine-induced elevation of plasma catecholamines was significantly attenuated by L-NAME (non-selective NOS inhibitor), carboxy-PTIO (NO scavenger), BYK191023 [selective inducible NOS (iNOS) inhibitor] and dithiothreitol (thiol-reducing reagent), but not by 3-bromo-7-nitroindazole (selective neuronal NOS inhibitor) or ODQ (sGC inhibitor). (±)-Epibatidine increased the number of spinally projecting PVN neurones with α4- and SNO-Cys-immunoreactivities, and this increment was reduced by BYK191023.

CONCLUSIONS AND IMPLICATIONS

Stimulation of brain nAChRs can induce elevation of plasma catecholamines through brain iNOS-derived NO-mediated protein S-nitrosylation in rats. Therefore, brain nAChRs (at least α4β2 subtype) and NO might be useful targets for alleviation of catecholamines overflow induced by smoking.

Abstract 5131: Efficient delivery of siRNA targeted CCDC88A mRNA to pancreatic cancer tumor inhibits the invasiveness and metastasis

Introduction: We identified CCDC88A messenger RNA (mRNA) that accumulates in lamellipodia by binding to an RNA-binding protein IGF2BP3 with a next generation sequencer. The objectives of this study are as follows: (1) To identify CCDC88A specific small interfering RNAs (siRNAs) as RNA interference agents that have an inhibitory effect on the invasion and metastasis of pancreatic cancer cells in a mouse model of the invasion and metastasis of pancreatic cancer; and (2) To develop a nucleic-acid delivery system to efficiently transport the siRNAs to PDAC tissue.

Methods: After intravenous injection of CCDC88A-specific siRNAs supplemented with folic acids that can bind to the folic acid receptor—which are highly expressed on pancreatic cancer cells—and polyethylene glycol-chitosan oligosaccharide nanoparticles to a mouse model of invasion and metastasis in which a human pancreatic cell line was transplanted to induce tumor formation in the mouse pancreas, accumulation of the siRNAs in the pancreatic cancer tissue was determined by using an in vivo imaging system. After CCDC88A-specific siRNA accumulation in the pancreatic cancer tissue was identified, invasion to the retroperitoneum as well as metastasis to the lung or liver from the human primary pancreatic tumor was compared between the mice in which CCDC88A-specific siRNA accumulation was identified and those receiving a scrambled control siRNA.

Results: CCDC88A-specific siRNAs could be delivered to the pancreatic cancer cells of cancer-bearing nude mice by supplementation with folic acids and chitosan oligosaccharide nanoparticles. Supplementation with folic acids and chitosan oligosaccharide nanoparticles caused no hemolysis and had no effect on liver, kidney, or pancreatic function. Invasion to the retroperitoneum and metastasis to the lung or liver from the primary pancreatic cancer were suppressed in cancer-bearing nude mice by administration of those siRNAs, which target CCDC88A mRNA accumulated in lamellipodia of pancreatic cancer cells.

Conclusions: This study suggests the potential to develop a siRNA drug to inhibit the invasion and metastasis of pancreatic cancer.

Citation Format: Keisuke Taniuchi, Toshio Yawata, Tetsuya Ueba, Toshiji Saibara. Efficient delivery of siRNA targeted CCDC88A mRNA to pancreatic cancer tumor inhibits the invasiveness and metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5131. doi:10.1158/1538-7445.AM2017-5131

Possible inhibitory role of endogenous 2-arachidonoylglycerol as an endocannabinoid in (±)-epibatidine-induced activation of central adrenomedullary outflow in the rat

We previously reported that intracerebroventricularly (i.c.v.) administered (±)-epibatidine (1, 5 or 10 nmol/animal), a nicotinic acetylcholine receptor agonist, dose-dependently induced secretion of noradrenaline and adrenaline (catecholamines) from the rat adrenal medulla by brain diacylglycerol lipase- (DGL), monoacylglycerol lipase- (MGL) and cyclooxygenase-mediated mechanisms. Diacylglycerol is hydrolyzed by DGL into 2-arachidonoylglycerol (2-AG), which is further hydrolyzed by MGL to arachidonic acid (AA), a cyclooxygenase substrate. These findings suggest that brain 2-AG-derived AA is involved in the (±)-epibatidine-induced response. This AA precursor 2-AG is also a major brain endocannabinoid, which inhibits synaptic transmission through presynaptic cannabinoid CB1 receptors. Released 2-AG into the synaptic cleft is rapidly inactivated by cellular uptake. Here, we examined a role of brain 2-AG as an endocannabinoid in the (±)-epibatidine-induced activation of central adrenomedullary outflow using anesthetized male Wistar rats. In central presence of AM251 (CB1 antagonist) (90 and 180 nmol/animal, i.c.v.), (±)-epibatidine elevated plasma catecholamines even at an ineffective dose (1 nmol/animal, i.c.v.). Central pretreatment with ACEA (CB1 agonist) (0.7 and 1.4 μmol/animal, i.c.v.), 2-AG ether (stable 2-AG analog for MGL) (0.5 and 1.0 μmol/animal, i.c.v.) or AM404 (endocannabinoid uptake inhibitor) (80 and 250 nmol/animal, i.c.v.) significantly reduced an effective dose of (±)-epibatidine- (5 nmol/animal, i.c.v.) induced elevation of plasma catecholamines, and AM251 (90 and 180 nmol/animal, i.c.v.) centrally abolished the reduction induced by 2-AG ether (1.0 μmol/animal, i.c.v.) or AM404 (250 nmol/animal, i.c.v.). Immunohistochemical studies demonstrated that (±)-epibatidine (10 nmol/animal, i.c.v.) activated DGLα-positive spinally projecting neurons in the hypothalamic paraventricular nucleus, a control center of central adrenomedullary system. These results suggest a possibility that a brain endocannabinoid, probably 2-AG, plays an inhibitory role in (±)-epibatidine-induced activation of central adrenomedullary outflow through brain CB1 receptors in the rat.

Prevalence of human cytomegalovirus, polyomaviruses, and oncogenic viruses in glioblastoma among Japanese subjects

Background

The association between human cytomegalovirus (HCMV) and glioblastoma multiforme (GBM) is becoming a new concept. However, information on the geographic variability of HCMV prevalence in GBM remains scarce. Moreover, the potential roles of various viruses, such as polyomaviruses and oncogenic viruses, in gliomagenesis remain unclear. Our aim was to investigate the prevalence of HCMV in GBM among Japanese patients. Furthermore, this was the first study that evaluated infection with four new human polyomaviruses in GBMs. This study also provided the first data on the detection of human papillomavirus (HPV) in GBM in the Eastern world.

Methods

We measured the number of various viral genomes in GBM samples from 39 Japanese patients using real-time quantitative PCR. The tested viruses included HCMV, Merkel cell polyomavirus, human polyomavirus (HPyV) 6, HPyV7, HPyV9, Epstein–Barr virus, human herpesvirus 8, and HPV. Our quantitative PCR analysis led to the detection of eight copies of the HCMV DNA mixed with DNA extracted from 10⁴ HCMV-negative cells. The presence of HCMV and HPV genomes was also assessed by nested PCR. Immunohistochemical study was also carried out to detect HPV-derived protein in GBM tissues.

Results

The viral DNAs were not detectable, with the exception of HPV, which was present in eight out of 39 (21%) GBMs. All HPV-positive cases harbored high-risk-type HPV (HPV16 and HPV18). Moreover, the HPV major capsid protein was detected in GBM tumor cells.

Conclusions

In contrast with previous reports from Caucasian patients, we did not obtain direct evidence in support of the association between HCMV and GBM. However, high-risk-type HPV infection may play a potential etiological role in gliomagenesis in a subset of patients. These findings should prompt further worldwide epidemiological studies aimed at defining the pathogenicity of virus-associated GBM.

Elevated cell invasion in a tumor sphere culture of RSV-M mouse glioma cells

Cancer stem cells (CSCs) are the sole population possessing high self-renewal activity in tumors, with their existence affecting tumor recurrence. However, the invasive activity of CSCs has yet to be fully understood. In this article, we established a tumor sphere culture of RSV-M mouse glioma cells (RSV-M-TS) and evaluated their migration and invasion activities. Histological analysis of a tumor formed by cranial injection of the RSV-M-TS cells showed highly invasive properties and similarities with human malignant glioma tissues. When the migration activity of both RSV-M and RSV-M-TS cells were compared by intracranial injection, rapid migration of RSV-M-TS cells was observed. To confirm the invasive capabilities of RSV-M-TS cells, a three-dimensional collagen invasion assay was performed in vitro using RSV-M, RSV-M-TS, and RSV-M-TS cells cultured with medium containing serum. RSV-M and RSV-M-TS cultured with medium containing serum for 8 days indicated low migration activity, while moderate invasion activity was observed in RSV-M-TS cells. This activity was further enhanced by incubation with medium containing serum overnight. To identify the genes involved in this invasion activity, we performed quantitative polymerase chain reaction (PCR) array analysis of RSV-M and RSV-M-TS cells. Of 84 cancer metastasis-related genes, up-regulation was observed in 24 genes, while 4 genes appeared to be down-regulated in RSV-M-TS cells. These results suggest that the enhanced invasive activity of glioma sphere cells correlates with a number of tumor metastasis-related genes and plays a role in the dissemination and invasion of glioma cells.

Angiotensin II acting on brain AT1 receptors induces adrenaline secretion and pressor responses in the rat

Angiotensin II (AngII) plays important roles in the regulation of cardiovascular function. Both peripheral and central actions of AngII are involved in this regulation, but mechanisms of the latter actions as a neurotransmitter/neuromodulator within the brain are still unclear. Here we show that (1) intracerebroventricularly (i.c.v.) administered AngII in urethane-anesthetized male rats elevates plasma adrenaline derived from the adrenal medulla but not noradrenaline with valsartan- (AT₁ receptor blocker) sensitive brain mechanisms, (2) peripheral AT₁ receptors are not involved in the AngII-induced elevation of plasma adrenaline, although AngII induces both noradrenaline and adrenaline secretion from bovine adrenal medulla cells, and (3) i.c.v. administered AngII elevates blood pressure but not heart rate with the valsartan-sensitive mechanisms. From these results, i.c.v. administered AngII acts on brain AT₁ receptors, thereby inducing the secretion of adrenaline and pressor responses. We propose that the central angiotensinergic system can activate central adrenomedullary outflow and modulate blood pressure.

Suppression of oxidative stress and 5-lipoxygenase activation by edaravone improves depressive-like behavior after concussion

Brain concussions are a serious public concern and are associated with neuropsychiatric disorders, such as depression. Patients with concussion who suffer from depression often experience distress. Nevertheless, few pre-clinical studies have examined concussion-induced depression, and there is little information regarding its pharmacological management. Edaravone, a free radical scavenger, can exert neuroprotective effects in several animal models of neurological disorders. However, the effectiveness of edaravone in animal models of concussion-induced depression remains unclear. In this study, we examined whether edaravone could prevent concussion-induced depression. Mice were subjected to a weight-drop injury and intravenously administered edaravone (3.0 mg/kg) or vehicle immediately after impact. Serial magnetic resonance imaging showed no abnormalities of the cerebrum on diffusion T1- and T2-weighted images. We found that edaravone suppressed concussion-induced depressive-like behavior in the forced swim test, which was accompanied by inhibition of increased hippocampal and cortical oxidative stress (OS) and suppression of 5-lipoxygenase (5-LOX) translocation to the nuclear envelope in hippocampal astrocytes. Hippocampal OS in concussed mice was also prevented by the nicotinamide adenine dinucleotide phosphate oxidase inhibitor, apocynin, and administration of BWB70C, a 5-LOX inhibitor, immediately and 24 h after injury prevented depressive-like behaviors in concussed mice. Further, antidepressant effects of edaravone were observed in mice receiving 1.0 or 3.0 mg/kg of edaravone immediately after impact, but not at a lower dose of 0.1 mg/kg. This antidepressant effect persisted up to 1 h after impact, whereas edaravone treatment at 3 h after impact had no effect on concussion-induced depressive-like behavior. These results suggest that edaravone protects against concussion-induced depression, and this protection is mediated by suppression of OS and 5-LOX translocation.

Attenuation of axonal injury and oxidative stress by edaravone protects against cognitive impairments after traumatic brain injury

Traumatic axonal injury (TAI), a feature of traumatic brain injury (TBI), progressively evolves over hours through impaired axonal transport and is thought to be a major contributor to cognitive dysfunction. In spite of various studies suggesting that pharmacologic or physiologic interventions might reduce TAI, clinical neuroprotective treatments are still unavailable. Edaravone, a free radical scavenger, has been shown to exert neuroprotective effects in animal models of several brain disorders. In this study, to evaluate whether edaravone suppresses TAI following TBI, mice were subjected to weight drop injury and had either edaravone (3.0mg/kg) or saline administered intravenously immediately after impact. Axonal injury and oxidative stress were assessed using immunohistochemistry with antibodies against amyloid precursor protein, a marker of impaired axonal transport, and with 8-hydroxy-2'-deoxyguanosine, a marker of oxidative DNA damage. Edaravone significantly suppressed axonal injury and oxidative stress in the cortex, corpus callosum, and hippocampus 24h after injury. The neuroprotective effects of edaravone were observed in mice receiving 1.0, 3.0, or 10mg/kg of edaravone immediately after impact, but not after 0.3mg/kg of edaravone. With treatment 1h after impact, axonal injury was also significantly suppressed and this therapeutic effect persisted up to 6h after impact. Furthermore, behavioral tests performed 9 days after injury showed memory deficits in saline-treated traumatized mice, which were not evident in the edaravone-treated group. These results suggest that edaravone protects against memory deficits following TBI and that this protection is mediated by suppression of TAI and oxidative stress.

Abstract 5362: Multidrug-resistance (MDR-1) gene expression in immature glioma cells

Cancer stem cell hypothesis suggests that small populations of stem-like cells exist in the tumor mass and harbor drug resistance and low radio-sensitivity, and thus resulting in tumor recurrence after various treatments. In this study, we investigated the relationship between cell differentiation and drug resistant gene expression in glioblastoma. Glioma stem-like cells freshly isolated from surgical specimens were enriched in tumor sphere (TS) culture and were more resistant to anti-cancer drugs compared with their differentiated cells in cell viability assay. These cells were also tested for phosphorylation of histone H2AX at Ser139, a biomarker of DNA lesions including DNA double-strand and single-strand breaks. Differentiated cells were much more susceptible to anti-cancer drug-induced DNA damage, compared with TS cells. The expression of drug resistance genes, MDR-1, MRP-1 and MRP-2 in TS cells was more than those in their differentiated cells by RT-PCR analysis. However, there was no correlation between drug resistance genes and stem cell marker CD133 expression. It is possibly caused by another cell population expressing drug resistance genes, therefore, we sought to define the existence of progenitor cells in glioma by detection of glial progenitor marker, A2B5 using flow cytometric analysis. CD133 and A2B5 positive cells were more abundant in TS cells and were decreased during induction of differentiation. The expression of MDR-1 was frequently observed in CD133+/A2B5−, CD133+/A2B5+ and CD133−/A2B5+ cells. Reduction of MDR-1 expression concomitantly occurred with the differentiation of these immature glioma cells. Thus, it is revealed that CD133 negative cells expressing MDR-1 are A2B5-positive glioma cells. These results suggest that drug resistance genes are expressed not only in tumor stem cells but also in progenitor cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5362. doi:1538-7445.AM2012-5362

Abstract 3402: Up-regulation and invasive role of MUC18/MCAM in glioma sphere culture

Glioblastomas are characterized by aggressive invasion into normal brain tissues, thus limiting complete removal by surgical resection resulting in recurrence. Our identified molecule involved in glioma invasion is important for developing targeted effective therapies in the malignant glioma. Cancer stem cells are capable for self-renewing and are thought to be responsible for tumor metastasis and dissemination. However, the invasive activities of cancer stem cells have not been fully understood. To investigate a role of glioma stem cells in the tumor invasion, tumor sphere culture was established from mouse glioma RSV-M cells. The high tumorigeneity and aggressive migration of RSV-M tumor sphere were observed in intracranial transplantation. Quantitative RT-PCR analysis showed the enhanced expression of metastasis-related genes in RSV-M tumor sphere. Of these, MUC18/MCAM also highly expressed in tumor sphere derived from human glioma cell lines. Importantly, CD133-positive fraction of glioma sphere culture isolated from glioblastoma patients contained a cell population expressing MUC18 but CD133-negative fraction not. To examine a function of MUC18 in glioma cells, the expression or knockdown construct for the gene were introduced into human glioma cells. Over-expression of MUC18 in the glioma cells increased their invasive capacity and clonogenicity in comparison to the parent or knockdown cells. In addition, expression of some metastasis-related genes was up-regulated in MUC18-over-expressing cells. These results suggest that enhanced MUC18 expression of glioma stem cells may contribute to the aggressive invasion of this tumor.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3402. doi:10.1158/1538-7445.AM2011-3402

Identification and functional characterization of glioma-specific promoters and their application in suicide gene therapy

Suicide gene therapy has been shown to be effective in inducing tumor regression. In this study, a human brain tumor-specific promoter was identified and used to develop transcriptionally targeted gene therapy. We searched for genes with brain tumor-specific expression. By in silico and reverse-transcription polymerase chain reaction screening, MAGE-A3 and SSX4 were found to be expressed in a tumor-specific manner. SSX4 gene promoter activity was high in human brain tumor cells but not in normal human astrocyte cells, whereas the MAGE-A3 promoter showed activity in both tumor and normal cells. A retrovirus vector carrying a suicide gene, the herpes simplex virus thymidine kinase gene controlled by the SSX4 promoter, was constructed to evaluate the efficacy of the promoter in tumor-specific gene therapy. Glioma and human telomerase catalytic subunit-immortalized fibroblast BJ-5ta cell lines transduced with retrovirus vectors were assayed for killing activity by ganciclovir. Glioma cell lines were effectively killed by ganciclovir in a concentration-dependent manner, whereas BJ-5ta cells were not. By contrast, MAGE-A3 promoter failed to induce cytotoxicity in a brain tumor-specific manner. In addition, mouse glioma RSV-M cells transduced with retrovirus vector also showed suppressed tumor formation activity in syngeneic mice in response to ganciclovir administration. Therefore, the SSX4 promoter is a candidate for brain tumor-specific gene therapy and supports the efficacy and safety of suicide gene therapy for malignant brain tumors.

Anti-invasive and antiangiogenic effects of MMI-166 on malignant glioma cells

Background

The constitutive overexpression of matrix metalloproteinases (MMPs) is frequently observed in malignant tumours. In particular, MMP-2 and MMP-9 have been reported to be closely associated with invasion and angiogenesis in malignant gliomas. Our study aimed to evaluate the antitumour effects of MMI-166 (Nalpha-[4-(2-Phenyl-2H- tetrazole-5-yl) phenyl sulfonyl]-D-tryptophan), a third generation MMP inhibitor, on three human glioma cell lines (T98G, U87MG, and ONS12) in vitro and in vivo.

Methods

The effects of MMI-166 on the gelatinolytic activity was analysed by gelatine zymography. The anti-invasive effect of MMI-166 was analysed by an in vitro invasion assay. An in vitro angiogenesis assay was also performed. In vitro growth inhibition of glioma cells by MMI-166 was determined by the MTT assay. The effect of MMI-166 on an orthotropic implantation model using athymic mice was also evaluated.

Results

Gelatine zymography revealed that MMP-2 and MMP-9 activities were suppressed by MMI-166. The invasion of glioma cells was suppressed by MMI-166. The angiogenesis assay showed that MMI-166 had a suppressive effect on glioma cell-induced angiogenesis. However, MMI-166 did not suppress glioma cell proliferation in the MTT assay. In vivo, MMI-166 suppressed tumour growth in athymic mice implanted orthotropically with T98G cells and showed an inhibitory effect on tumour-induced angiogenesis and tumour growth. This is the first report of the effect of a third generation MMP inhibitor on malignant glioma cells.

Conclusions

These results suggest that MMI-166 may have potentially suppressive effects on the invasion and angiogenesis of malignant gliomas.

Abstract 587: Development of brain tumor-specific targeted system by using retroviral-mediated gene therapy with SSX4 promoter

Despite many efforts to develop effective therapy, the outcome of malignant glioma remains poor. Previously, we reported the eradication of mouse glioma by retroviral-mediated gene therapy. In this study, a tumor-specific targeting system was studied to develop the effective and safe gene therapy. We first searched for genes expressing at high frequency in brain tumors but not in normal human astrocyte (NHA) among cancer testis antigen (CTA) genes by in silico and RT-PCR screening. MAGEA3 and SSX4 were identified as tumor-specific genes. The promoter activity was measured in glioma, telomerase-immortalized fibroblast and NHA cells. The SSX4 promoter but not MAGEA3 showed the tumor-specific activity. In order to define a useful tumor-specific promoter for targeting in context of retroviral-mediated gene therapy, the SSX4 promoter were used to restrict the expression of suicide gene HSVtk in retroviral vector. The glioma cell lines transduced with the retroviral vector were killed efficiently by addition of ganciclovir (GCV), but telomerase-immortalized fibroblast BJ-5ta cells were not. Mouse glioma RSV-M cells transduced with the retroviral vector were transplanted into S.C. of syngeneic mouse. The administration of GCV suppressed the tumor growth completely. These results suggest that trans-acting factors may play a role for tumor-specific activity of SSX4 promoter while the expression of most CTA genes is regulated by epigenetic factors and the retrovirus vector expressing HSVtk under control of SSX4 promoter is a promising therapeutic reagent for malignant brain tumors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 587.

Enhanced MDR1 expression and chemoresistance of cancer stem cells derived from glioblastoma

We established a cancer stem (CS) cell line, U87CS, by means of spheroid culture of U87MG cells derived from glioblastoma (GBM) in neuronal stem cell medium. U87CS cells presented positive immunohistochemical staining for multidrug resistance (MDR)1 and CD133, a marker for a subset of leukemia and GBM CS cells. The gene expression of MDR1 and CD133 on U87CS cells increased by an average of 8.51 and 47.18 times, respectively, compared to the levels on U87MG cells by real-time quantitative RT-PCR. U87CS cells possessed stronger drug-resistance to conventional anti-cancer drugs, such as doxorubicin (Dox), etoposide (VP-16), carboplastin, and BCNU than U87MG cells. Double immunofluoresence staining showed co-expression of MDR1 and CD133 on U87CS cells transplanted into nude mice brains. In addition, we identified the crossreactivity of CD133 and MDR1 in a surgical specimen of GBM. Our results suggest that CS cells may be resistant to current chemotherapy and represent a novel target for GBM therapeutics.

Identification of a </= 600-kb region on human chromosome 1q42.3 inducing cellular senescence

The introduction of a human chromosome 1 via microcell-mediated chromosome transfer (MMCT) induces the cellular senescence in mouse melanoma B16-F10 cells. The senescent cells maintained still the telomerase activity, which is frequently associated with immortal growth of human cells, suggesting that a telomerase-independent mechanism is involved in the senescence observed in this mouse cell line. To map the senescence-inducing gene to a specific chromosomal region, we took two experimental approaches: identification of a minimal region with the senescence-inducing activity via MMCT of a series of subchromosomal transferrable fragments (STFs), each consisting of a different profile of human chromosome 1-derived regions, and identification of a region commonly deleted from the transferred chromosome 1 in the revertant clones that escaped cellular senescence. These approaches identified a 2.7-3.0 Mb of senescence-inducing region shared among the active STFs and a 2.4-3.0 Mb of commonly deleted region in the revertant clones. These two regions overlapped each other to map the responsible gene at the 450 to 600-kb interval between UniSTS93710 and D1S3542 on chromosome 1q42.3. This study provides essential information and materials for cloning and characterization of a novel senescence-inducing gene that functions in a telomerase-independent pathway, which is likely to be conserved between mice and humans.

Cerebrospinal fluid sodium concentration and osmosensitive sites related to arterial pressure in anaesthetized rats

Intracerebroventricular injection of hypertonic saline induces experimental hypertension. To measure [Na] in the vicinity of osmosensitive sites, we continuously measured [Na] in cerebrospinal fluid ([Na]csf) in the lateral ventricle (LV, n = 6), in the third ventricle (V3, n = 6) and in the medial preoptic nucleus (MPO, n = 6) ([Na]MPO) with a Na-sensitive electrode together with mean arterial pressure (MAP) during infusion of hypertonic artificial cerebrospinal fluid (ACSF, [Na] = 1,000 meq/kg H2O) at 5 "mu"l/min for 3 min into the LV in urethane- anaesthetized rats. [Na]csf in the LV began to increase at the beginning of infusion, reaching a peak of 48 +/- 9 meq/kg H2O (mean +/- SE) around the end of infusion, then recovering to the pre-infusion level by 17 min. [Na]csf in V3 changed similarly to that in the LV without any delay, although the peak value was reduced (61% , P < 0.05). In the MPO, in contrast the increase in [Na]MPO was delayed (3 min, P < 0.002) and the peak reduced even further (to 37%, P < 0.01) compared with that in V3. Thereafter, it remained higher than the pre-infusion level until the end of recovery (P < 0.05). MAP began to increase at the onset of infusion (P < 0.05); the maximum increase of 16 +/- 2 mm Hg (n = 18) was reached at the end of infusion, whereafter this level was almost sustained until the end of the 22-min recovery period. To analyse quantitatively the relationship between MAP and [Na]csf, hypertonic ACSF was infused at 2.5 "mu"l/min into the LV. [Na]csf in the LV and MAP increased at half the rates seen with 5 "mu"l/min. These results suggest that the first increase in MAP after hypertonic infusion into the LV is due to the increase in [Na] in the LV and V3, and that the subsequent sustained increase in MAP is related to the delayed increase in [Na] in the periventricular tissues of the V3.

Cosmids and transcribed sequences from chromosome 11q23

To obtain cosmid markers and transcribed sequences from a specific chromosome region, a series of radiation-reduced hybrids (RHs) containing various regions of human chromosome 11 was prepared from microcell hybrid A9 (neo11) cells containing a normal human chromosome 11 tagged with pSV2neo at 11p11.2. Among 15 radiation hybrid clones isolated, RH(11)-9 which contains a q23 fragment in addition to the neo integration site, was used for the construction of a cosmid library. Cosmid clones having human DNA sequences were screened, and localized by Southern hybridization with the radiation hybrid panel. Fifty-nine cosmids were assigned to 11q23 and 6 cosmids to 11p11.2. Exon amplification proceeded with 23 of the 59 cosmids and 16 putative exons were cloned. Three of them were identical to those constituting a known gene which locates on q23 (ATDC), and the others were unknown. Thus, the RHs containing various subchromosomal fragments of chromosome 11 were useful for constructing region-specific DNA markers. The RH(11)-9 cells and putative exons also facilitate the positional cloning of genes in the 11q23 region.

Effect of potassium solution on rehydration in rats: comparison with sodium solution and water

Thermally dehydrated rats were given isotonic KCl, NaCl solution, or tap water ad libitum for 17 h and the differences of the restoration rate in fluid and cation were compared between the groups to elucidate the effect of Na+ and K+ ions on the replacement of each body fluid compartment during rehydration. When rats were provided with NaCl solution, the gains of fluid and Na+ exceeded the amounts lost during the dehydration period, while in the isotonic KCl and tap water groups fluid gain was 70% of the fluid lost during the dehydration period. The recovery of extracellular fluid (ECF) volume was 178% of the loss in the NaCl group and 50% in the KCl group. The Na+ concentration of the ECF was regulated closely in all groups. The recovery in intracellular fluid (ICF) volume did not differ significantly between groups and never exceeded the control level, but tended to be higher in the KCl group than in the NaCl group. These results indicated that in the ECF the regulation of Na+ concentration preceded that of volume while in the ICF, volume regulation had priority. In addition, the effect of K+ supplementation on the recovery of ICF volume after thermal dehydration was shown to be modest, unlike the effect of Na+ on the recovery of ECF volume.

Effect of ANP on circulating blood volume

The effects of rat atrial natriuretic peptide (rANP) on blood volume (BV) were determined by the continuous measurement of BV, mean arterial pressure (MAP), and central venous pressure (CVP). Immediately after a single-bolus injection of rANP-(1-28), 1 nmol/100 g body wt, in conscious rats, BV began to decrease. Peak reduction of -0.22 +/- 0.03 ml/100 g body wt was reached 14.5 min after the injection. Thereafter, BV levels returned gradually to -0.08 +/- 0.03 ml/100 g body wt compared with the control value. In volume expansion experiment, the nephrectomized, anesthetized rats were divided into two groups: the control group, with only a saline infusion, and the ANP group, with an infusion of saline with rANP (1 nmol/100 g body wt). In the ANP group, increases in BV were not as great, and recovery was threefold faster than that of the control group. In the ANP group, the recovery time of BV to the starting control levels was 8.5 min, and the time constant of recovery was 3.6 +/- 0.3 min-1. The control group times were 25 min and 11.5 +/- 0.8 min-1, respectively. The effective vascular compliances were approximately 2.8 ml.mmHg-1.kg body wt-1 in both groups, and the capillary filtration coefficient was 0.47 ml.mmHg-1.min-1.kg body wt-1 in the ANP group and 0.33 ml.mmHg-1.min-1.kg body wt-1 in the control group. Thus the whole body capillary filtration coefficient was 1.5-fold higher in the ANP group than in the control group. This suggests that ANP may increase the permeability of capillaries.

Difference in rehydration process due to salt concentration of drinking water in rats

Albino rats were thermally dehydrated (approximately 8% of body wt), divided into five groups, and given tap water or 0.2, 0.45, 0.9, or 2.0% NaCl solution ad libitum for 16 h. Rats given 0.9 or 0.45% NaCl solution regained fluid loss completely in 3-3.5 h, whereas those given 0.2% solution became fully rehydrated at 10 h. The rats in the tap water and 2.0% NaCl groups were only 78 and 59% rehydrated, respectively, within 16 h. Na balance was positive in the 0.9% NaCl group by about five times the amount of the cations lost during the dehydration period. A positive balance of Na was also observed in the 0.45 (approximately 250%) and 2.0% NaCl groups (300%), whereas the 0.2% NaCl group regained lost water and Na simultaneously at 10 h. With tap water, additional loss of cations was observed. These findings show that for the replacement of water due to thermal dehydration there is a range of NaCl concentration with which the rats can rehydrate with the mutual cooperation of thirst, salt appetite, and kidney function.

Change in salt appetite due to rehydration level in rats

Thermally dehydrated rats were given a choice of tap water and saline (0.9% or 1.8% NaCl), and the change in the salinity of their choice during rehydration was measured up to 15 hr. The rats consumed more water than saline for about 2 hr after the start of fluid replacement (about 55 mEq/l), while they consumed more saline than tap water (about 120 mEq/l) thereafter. Urine output and urinary Na output were only about 20% of their intake during the initial 4 hr of rehydration, while after 4 hr the output became almost equal with the intake. The change in salt intake occurred when about 90% of Na loss and 60% of fluid loss was regained. The results indicate that rats choose dilute salt solution to lower plasma osmolality during the initial period of the rehydration and then regain body fluid isotonically. Urine volume and urinary Na output increased only after volume repletion. Thus, osmoregulation with salt appetite has priority over fluid volume regulation in restitution from thermal dehydration.

Recovery of blood volume and osmolality after thermal dehydration in rats

Changes in blood volume and fluid intake were assessed continuously during recovery from thermal dehydration (approximately 6 ml/100 g body wt) in rats. Catheters chronically implanted into the jugular vein and descending aorta were connected with the system for continuous monitoring of blood volume. Changes in blood volume and fluid consumption were recorded for 2-6 h while tap water (TW group) or 0.45% NaCl solution (Na group) was provided ad libitum. As soon as the fluids became available, the rats in both groups drank a relatively large volume (2-3 ml/100 g) within 10 min. Thereafter, Na group consumed approximately 1 ml X 100 g body wt-1 X 30-60 min-1 and regained almost all water loss in 2 h, whereas TW group drank only approximately 50% of their water deficit. The percent of ingested fluid that remained in vascular space was 17% on average in both groups. Thus TW group replenished 80% of the depleted blood volume, whereas Na group regained almost all of it. Rehydration for 2 h decreased plasma Na concentration to the control level in TW group, whereas in Na group the level remained high. These results suggest that the lower fluid intake in TW group is due to the dilutional inhibition of drinking and that the osmoregulation has priority over blood volume regulation in restitution from thermal dehydration.

Continuous determination of blood volume on conscious rats during water and food intake

A method to measure circulating blood volume continuously on a conscious rat was developed using the dilution method of 51Cr-labelled red cell and changes in blood volume after drinking and food intake were monitored. In splenectomized rats, the blood volume showed a transient decrease of 0.1-0.2 ml/100 g body wt. about 30 min after food intake, while increasing by 0.1-0.4 ml/100 g body wt. after water ingestion. Thus, blood volume showed fluctuations following water and food intake ranging from 2-8% of the circulating blood volume.

Osmotic factors in restitution from thermal dehydration in rats

The degree of voluntary dehydration after thermal dehydration was assessed while supplying drinking water of varying NaCl concentrations. Adult male albino rats were exposed to a hot-dry environment (dry bulb temp 36 degrees C; relative humidity 20%) for 6-8 h, and dehydration of 7% body wt was induced. After dehydration the rats were divided into three groups, and distilled water and 0.45 or 0.9% NaCl solution was given ad libitum. The amount of fluid intake reached an equilibrium in 6-12 h; the 0.45 and 0.9% NaCl groups regained almost all lost water, whereas the distilled water group regained only half. During rehydration the 0.45 and 0.9% NaCl groups gained Na by approximately 430-650 mueq and lost K by 90-130 mueq, whereas the distilled water group lost Na slightly and K by 80 mueq/100 g body wt. As for the electrolyte balance during thermal dehydration, rats excreted Na and K into urine and saliva. Na loss was 200 mueq/100 g, almost all of which was derived from the interstitial space of skin and skeletal muscle, and K loss was 230 mueq/100 g, almost all of which was derived from intracellular space of skeletal muscle. Total cation loss (Na, K) during thermal dehydration, including K excretion during rehydration, was 510-560 mueq/100 g, which was almost identical to the Na gained by rats given 0.45 or 0.9% NaCl solution. These results suggest that voluntary dehydration is caused by the dilutional inhibition of drinking due to loss of electrolytes during thermal dehydration.

Toxic effects of Kintoki bean (Phaseolus vulgaris) lectin on cultured animal cells

Effects of a toxic lectin from Kintoki beans (Phaseolus vulgaris, cultivar, Kintoki) on four types of animal cells were investigated. The cells used in this study were mouse L 929, human HeLa S3, and tendon and liver cells from chick embryo. The Kintoki bean lectin agglutinated these cells not only in suspension but also in monolayer, resulting in the marked growth inhibition of these cells. The incorporations of 3H-thymidine and 3H-leucine into trichloroacetic acid insoluble fraction of the cells were considerably inhibited by this lectin. There was, however, some lag period before the revelation of the inhibition. Kintoki bean lectin bound to these cells within 1 hr. The type of the lectin receptor seemed uniform for each cell type and the number of the binding sites per cell was different from cell type to cell type. When Kintoki bean lectin was removed from the culture medium, these cells slowly recovered back to normal growth.

The lethal protein from Kintoki beans (Phaseolus vulgaris) identified as a lectin

A glycoprotein isolated from Kintoki beans (Phaseolus vulgaris cultivar Kintoki) agglutinated human erythrocytes of all types and erythrocytes of rat, rabbit, sheep, and mouse. The lectin activity was not affected by 1 hr heating at 60 degrees C, but decreased slightly on heating for the same period at 70-80 degrees C and markedly at 90-100 degrees C. The activity was inhibited by galactose, lactose, N-acetyl galactosamine and fetuin. The inhibition was, however, weak, as often found for nonspecific lectins. The activity did not change when tyrosine residues or small parts of amino groups were modified, but decreased considerably when histidine residues or carboxyl groups were modified. This lectin was found to be relatively resistant to trypsin, and, particularly, to pepsin. All mice died within 48 hr when 200 microgram lectin per gram body weight was injected intraperitoneally and 14 microgram intravenously. The toxic activity changed in parallel with the lectin activity upon various treatments of the glycoprotein. In addition, blood analyses of injected mice suggested that the toxicity might be developed by the action of the lectin on blood cells.

Further characterization of rennin action on kappa-casein using carboxymethylcellulose: effects of various additives on the enzymatic hydrolysis of kappa-casein

The effects of various additives on the reaction of rennin with kappa-casein were investigated by using carboxymethylcellulose. Both urea and sodium 1-anilino-8-naphthalenesulfonate effectively inhibited rennin action at concentrations larger than 2 M and 2 mM, respectively. These reagents, however, activated the enzyme action at the lower concentrations. Both alpha S-and beta-caseins had some ranges of concentrations in which the rennin reaction was activated. Calcium chloride had an inhibitory effect on the rennin action. Neither mercaptoethanol nor KCl had any appreciable effect on the enzymatic hydrolysis of kappa-casein. These results are analyzed in terms of the association and dissociation of kappa-casein due to the presence of these additives in the reaction solutions.