Lentivirus-mediated CD/TK fusion gene transfection neural stem cell therapy for C6 glioblastoma

A suicide gene can convert nontoxic prodrugs into toxic products to kill tumor cells. In this study, our aim was to transfect lentivirus-mediated CD/TK fusion gene into Wistar rat’s neural stem cells (NSC) and then implant the NSC into a C6 glioma model to observe a C6 glioma growth inhibition effect. Primary NSC and stable transfection CD/TK fusion gene cell lines were established. To observe the tumor size and rat survival period in different groups, C6 glioma cell apoptosis and cell viability rate were applied to analyze the tumor inhibition effect of the neural stem cells’ transfected CD/TK fusion gene. C6 cell viability showed that CDglyTK-NSC + GCV/5-Fc (group 1) was lower than CDglyTK-NSC (group 2), NSC + GCV/5-Fc (group 3), and control (group 4) from day 2 (p?<?0.05), and the apoptosis rate was higher in group 1 compared with that of other groups (50.6 %, p?<?0.05) either in vitro or in vivo (35.47 %, p?<?0.05); both cell viability and apoptosis had no significance in the other three groups. In vivo, tumor size in group 1 was 7.76?±?1.37 mm³, which is smaller than the others (group2 27.28?±?4.11 mm³, group3 27.94?±?2.08 and 28.61?±?2.97 mm³; p?<?0.05). The other groups’ tumor size was not significant (p?>?0.05). Survival time of rats treated with CDglyTK-NSC + GCV/5-Fc (group 1) was significantly longer than that of the other groups (p?<?0.05; group 1 48.86?±?1.97, group 2 28.67?±?3.75, group 3 31.5?±?1.27, group 4 29.3?±?1.33). We also showed that the transfected C6 cells had a migratory capacity toward gliomas in vivo. Transfected CD/TK fusion gene neural stem cells combined with propyl–guanosine and 5-flucytosine double prodrug significantly inhibit the development of glioma.     

Investigation of a plasmid containing a novel immunotoxin VEGF165‐PE38 gene for antiangiogenic therapy in a malignant glioma model

Inhibition of tumor neovascularization has profound effects on the growth of solid tumors. Our previous studies have shown the effect of VEGF165‐PE38 recombinant immunotoxin on proliferation and apoptosis in human umbilical vein endothelial cells in vitro. In this study, we explored the direct inhibition of angiogenesis in chick chorioallantoic membrane and antiangiogenic therapy in a malignant glioma model. HEK293 cells were transfected with the pVEGF165PE38‐IRES2‐EGFP plasmid. ELISA was used to confirm the expression of VEGF165‐PE38 in the transfected cells. These cells released 1396 ± 131.9 pg VEGF165‐PE38/1×10⁴ cells/48 h into the culture medium and the supernatant was capable of inhibiting the growth of capillary‐like structures in chick chorioallantoic membrane assay. In a murine malignant glioma model, plasmid was directly administered via multiple local intratumoral delivery. After day 16 the tumor volume in mice treated with pVEGF165PE38‐IRES2‐EGFP was significantly lower than that in mice in the control groups. Immunohistochemistry studies showed that the treated group had decreased expression of CD31. Quantitative analysis of microvessel density in the treated group was 1.99 ± 0.69/0.74 mm², and was significantly lower than that in the control groups (9.33 ± 1.99/0.74 mm², 8.09 ± 1.39/0.74 mm² and 8.49 ± 1.69/0.74 mm²). Immunohistochemistry analysis indicated that immunotoxin VEGF165‐PE38 was distributed in the treated group in malignant glioma tissue. Our findings provide evidence that the in vivo production of VEGF165‐PE38 through gene therapy using a eukaryotic expression plasmid had potential antiangiogenic activity in malignant glioma in vivo.     

AQP-4 in peritumoral edematous tissue is correlated with the degree of glioma and with expression of VEGF and HIF-alpha

It is recognized that expression of AQP4 protein is much greater in gliomas than in normal tissue. The relationship between AQP4 and glioma-associated brain edema is affected by osmotic pressure and hypoxia. In this study, we detected changes of AQP4 expression in tumor and peritumoral edematous tissues to analyze the relationship between AQP4 protein and the edema index (EI). We also detected expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1α (HIF-1α) to investigate their relationship with AQP4 protein, and thus to uncover the molecular biological mechanisms of AQP4 expression in glioma-associated brain edema. Sixty-five patients with brain glioma were divided into tumor and peritumor groups. Fresh tumor specimens, including six cases of grade I glioma, 18 of grade II, 11 of grade III and 30 of grade IV, and peritumoral edematous tissue specimens (1 cm distant from the tumor) were resected from these patients, and AQP4 protein expression levels were detected by western blot. Different AQP4 expression in the tumor and peritumor groups were compared. The relationship between AQP4 expression levels and the degree of peritumoral edema, and expression differences in different grades, were analyzed. Immunofluorescence cytochemistry was used to detect positive expression of AQP4 protein, VEGF protein, and HIF-1α protein in tumor tissue, and differences between expression were analyzed. Western blot showed that AQP4 expression in the peritumor (0.7697 ± 0.0941) and tumor (0.6934 ± 0.0625) groups was higher than in the control group (0.6215 ± 0.0884), and was highest in the peritumor group (both P < 0.01). AQP4 expression level in the peritumor group was positively correlated with EI (r = 0.677, P < 0.001) whereas AQP4 expression level in the tumor group was not correlated with EI (r = 0.096, P > 0.05). AQP4 expression increased with higher tumor grades in the peritumor group, but differences were not significant in the tumor group. Immunofluorescence cytochemical staining revealed that AQP4 protein in normal brain tissue was mainly expressed in the cell membrane surface, and that cytoplasm and nuclear staining was shallow. In glioma cells, AQP4 was widely distributed in the cytoplasm, particularly in the edematous area around the tumor. AQP4 protein expression in the tumor was significantly positively correlated with both VEGF protein (r = 0.877, P < 0.001) and HIF-1α protein (r = 0.876, P < 0.001). AQP4 expression was higher in brain tumor, especially peritumor. The degree of peritumoral edema correlates with AQP4 protein expression only in peritumor, whereas AQP4 expression is in accordance with expression of VEGF and HIF-1α. In glioma-associated brain edema, AQP4 is coregulated by osmotic pressure and hypoxia, with predominance of osmotic regulation, and is redistributed in glioma cells, mainly in the cytoplasm, and its expression level increased with higher glioma grades.     

The temozolomide derivative 2T-P400 inhibits glioma growth via administration route of intravenous injection

The aim of this study is to investigate the inhibitory effects of 2T-P400, a derivative of temozolomide (TMZ), on glioma growth. SHG-44 and U373 human glioblastoma cell lines and SHG-44 cell subcutaneous and intracranial xenograft mouse models were used as the model system for these studies. Cell growth was analyzed using MTT assay. For intracranial glioma xenograft model, mouse brains were obtained and made as paraffin section for immunohistochemical staining. Tumor volume was calculated with this formula: tumor volume = length × width²/2. The results showed that 2T-P400 or TMZ significantly inhibits cell growth in a concentration dependent manner with the IC50 values of 12.90 ± 1.05 or 9.73 ± 2.12 μg/ml on SHG-44 cell line and 13.12 ± 0.86 or 10.13 ± 1.02 μg/ml on U373 cell line respectively. In SHG-44 cell subcutaneous xenograft model, the tumor volume of 2T-P400 or TMZ treated group was 1,062.12 ± 204.76 or 803.59 ± 110.32 mm³ respectively, which was significantly smaller than that in physiological saline (with volume of 1,968.85 ± 348.37 mm³) treated group. In intracranial xenograft model, the tumor volume of 2T-P400 or TMZ group was 6.12 ± 1.69 or 5.58 ± 1.45 mm³ respectively, significantly smaller than that in physiological saline group of 33.08 ± 6.88 mm³. Moreover, polyethylene glycol 400 (PEG400) exhibited no significant tumor growth inhibition. Our results indicated that 2T-P400 posses the same growth inhibitory effect as TMZ on glioblastoma cell lines and the subcutaneously and intracranially transplanted gliomas in xenograft mouse models. It may be a suitable alternate of TMZ for the treatment of glioma via intravenous administration route.     

Antitumor and antivascular effects of AC-7700, a combretastatin A-4 derivative,against rat liver cancer

Background. Unlike the many chemotherapeutic agents that do not effectively stop blood flow or induce necrosis in hepatocellular carcinoma, AC-7700 has been shown to inhibit tubulin polymerization and selectively stop tumor blood flow. The aim of this study was to elucidate the antivascular and antitumor effects of AC-7700 on rat hepatoma. Methods. AH-130 cells, a rat hepatoma cell line, were solidified and implanted into the liver of Donryu rats. Vascularity of the liver tumor was directly identified by in-vivo fluorescence microscopy from 0 to 60 min after the injection of 10 mg/kg AC-7700. To observe the antivascular effect of AC-7700, the vascular density of the tumor was measured and assessed as the ratio of preinjection to postinjection values. The antitumor effects were evaluated with histopathologic findings and analysis of animal survival. Results. In-vivo microscopic observation showed that tumor perfusion diminished within 30 min after AC-7700 administration. Vascular density in the AC-7700 group was significantly less than that in the control group at 60 min (AC-7700, 26.3 ± 16.4%; control, 88.5 ± 9.2%; P < 0.001). After AC-7700 injection, marked necrosis of tumor cells was observed histologically, and tumor area was decreased significantly (AC-7700, 11.5 ± 15.4 mm²; control, 43.5 ± 18.3 mm²; P < 0.05). The survival rate (50%) of the AC-7700 group animals was better than that of the control group (0%; P < 0.01). Conclusion. Markedly decreased tumor perfusion was induced by AC-7700 within 30 min, and this decrease may have contributed to the tumor necrosis and favorable outcome in the treatment group. AC-7700 appears to be a promising agent for the treatment of hepatocellular carcinoma. Received: September 14, 2001 / Accepted: February 21, 2002     

Anti-proliferative effect of the gastrin-release peptide receptor antagonist RC-3095 plus temozolomide in experimental glioblastoma models

Malignant gliomas have a dismal prognosis despite multi-modality treatments like neurosurgical resection, radiation therapy and chemotherapy. Evidence has indicated that gastrin-releasing peptide (GRP) and its receptor (GRPR) play a role in the development of a variety of cancers including gliomas. In the present study, we investigated the effects of RC-3095, a selective GRPR antagonist, alone or in combination with temozolomide (TMZ), a DNA alkylating agent, in in vitro and in vivo experimental rat C6 glioma models. Cellular proliferation was significantly reduced by all treatments with the combined administration of TMZ and RC-3095 being the most effective treatment. In in vivo experiments, the control group displayed the largest tumors (52 ± 15.5 mm³), whereas RC-3095 reduced the tumor size, with the most significant effect at the dose of 0.3 mg/kg (21 ± 9.7 mm³). The combined therapy produced further reduction in tumor size (10 ± 7.5 mm³). Our results show that the combination of RC-3095 with TMZ produced an important reduction in in vitro and in vivo glioma growth therefore making RC-3095 a candidate drug to potentiate the effects of the DNA alkylating agent TMZ in the treatment of glioma. An erratum to this article can be found at     

Glioma-related edema:new insight into molecular mechanisms and their clinical implications

Glioma-related edema(GRE) is a significant contributor to morbidity and mortality from glioma.GRE is a complicated process involving not only peritumoral edema but also the water content of the tumor body.In terms of etiology,this condition derives from both GRE in the untreated state and GRE secondary to clinical intervention,and different cell types contribute to distinct components of GRE.Peritumoral edema was previously believed to loosen glioma tissue,facilitating tumor-cell invasion;however,the nutrition hypothesis of the tumor microecosystem suggests that tumor cells invade for the sake of nutrition.Edema is the pathologic consequence of the reconstructed trophic linkage within the tumor microecosystem.Glioma cells induce peritumoral brain edema via an active process that supplies a suitable niche for peritumoral invasive cells,suggesting that glioma-related peritumoral brain edema is determined by the invasive property of tumor cells.There are differences between pivotal molecular events and reactive molecular events in the development of GRE.Molecular therapy should target the former,as targeting reactive molecular events will produce undesired or even adverse results.At present,brain glioma angiogenesis models have not been translated into a new understanding of the features of brain images.The effect of these models on peritumoral brain edema is unclear.Clinical approaches should be transformed on the basis of new knowledge of the molecular mechanism underlying GRE.Exploring clinical assessment methods,optimizing the existing control strategy of GRE,and simultaneously developing new treatments are essential.     

瘤周水肿区ADC值在恶性胶质瘤及脑转移瘤鉴别诊断中的价值

[目的]探讨MR扩散加权成像（DWI）瘤周水肿区表观扩散系数（ADC）值在恶性胶质瘤及脑转移瘤鉴别诊断中的价值。[方法]32例恶性胶质瘤（≥Ⅲ级）和24例脑转移瘤患者进行常规MRI扫描和DWI检查。分析比较两者肿瘤的边缘特征及瘤周近、远侧水肿带的表观扩散系数（ADC）和相对表观扩散系数（rADC）。[结果]恶性胶质瘤近瘤水肿带的ADC值及rADC值分别为1.44×10-3±0.15×10-3mm2/s和2.01±0.24,远瘤水肿带分别为1.81×10-3±0.21×10-3mm2/s和2.49±0.33。脑转移瘤近瘤水肿带的ADC值及rADC值分别为1.70×10-3±0.22×10-3mm2/s和2.43±0.44,远瘤水肿带分别为1.81×10-3±0.18×10-3mm2/s和2.54±0.41。恶性胶质瘤和脑转移瘤近瘤水肿带的ADC值和rADC值之间的差异有统计学意义（P〈0.01）,而远瘤水肿带间的差异无统计学意义（P〉0.05）;恶性胶质瘤近、远瘤水肿带的ADC值和rADC值之间的差异有统计学意义（P〈0.01）;脑转移瘤近、远瘤水肿带的ADC值和rADC值之间的差异无统计学意义（P〉0.05）。[结论]在DWI上,恶性胶质瘤和脑转移瘤的边缘特征以及瘤周近、远侧水肿带的ADC值及rADC值的差异对两者的鉴别诊断具有重要价值。     

Plasma and cerebrospinal fluid pharmacokinetics of the novel tetrahydroisoquinoline EDL-155 in rats

Purpose Tetrahydroisoquinolines (THIs) have demonstrated anti-cancer activity in rodent models of glioma, a form of brain cancer refractory to therapeutic intervention. In this study, peripheral and cerebrospinal fluid (CSF) pharmacokinetics in rats were determined to assess the drug developability of the novel THI EDL-155 for the treatment of glioma. Methods Serial blood and CSF samples were collected from rats following intravenous bolus administration of EDL-155 (10–20 mg/kg). Samples were analyzed by LC/MS/MS. Pharmacokinetic analyses using compartmental and noncompartmental methods were performed using the computer program WinNonlin. Plasma protein binding was measured using the charcoal adsorption method. The in vivo efficacy of EDL-155 (i.p. 20 mg/kg twice daily for 7 days) was assessed in rats with stereotactically implanted C6 glioma cells into the caudate. Results EDL-155 plasma concentration data were described by a one-compartment model. EDL-155 demonstrated rapid clearance (342.5 ± 49.9 ml/min/kg), high volume of distribution (13.0 ± 1.2 l/kg) and a terminal half-life of 23.7 ± 1.5 min. Dose-normalized CSF area under the curve (AUC_CSF) as a percentage of peripheral exposure (AUC_Plasma) was 1.4%. EDL-155 was highly bound to plasma proteins (>93%). Intracranial tumor volume at 7 days post-implantation was approximately 30% smaller in animals treated with EDL-155 when compared to vehicle control animals (13.2 ± 5.3 mm³ vs. 18.7 ± 6.3 mm³; P = 0.04). Conclusion High clearance and extensive protein binding limit the brain availability of EDL-155 following systemic administration. EDL-155 treatment resulted in reduced tumor size despite limited blood brain barrier penetrability, which suggests that analogs with increased metabolic stability and brain penetrability may provide a therapeutic option for primary central nervous system tumors such as glioma. On-going studies are focused on the design, synthesis, and testing of novel analogs based upon these findings.     

Recombinant Interleukin-1 Receptor Antagonist Conjugated to Superparamagnetic Iron Oxide Nanoparticles for Theranostic Targeting of Experimental Glioblastoma

Cerebral edema commonly accompanies brain tumors and contributes to neurologic symptoms. The role of the interleukin-1 receptor antagonist conjugated to superparamagnetic iron oxide nanoparticles (SPION–IL-1Ra) was assessed to analyze its anti-edemal effect and its possible application as a negative contrast enhancing agent for magnetic resonance imaging (MRI). Rats with intracranial C6 glioma were intravenously administered at various concentrations of IL-1Ra or SPION–IL-1Ra. Brain peritumoral edema following treatment with receptor antagonist was assessed with high-field MRI. IL-1Ra administered at later stages of tumor progression significantly reduced peritumoral edema (as measured by MRI) and prolonged two-fold the life span of comorbid animals in a dose-dependent manner in comparison to control and corticosteroid-treated animals (P < .001). Synthesized SPION–IL-1Ra conjugates had the properties of negative contrast agent with high coefficients of relaxation efficiency. In vitro studies of SPION–IL-1Ra nanoparticles demonstrated high intracellular incorporation and absence of toxic influence on C6 cells and lymphocyte viability and proliferation. Retention of the nanoparticles in the tumor resulted in enhanced hypotensive T₂-weighted images of glioma, proving the application of the conjugates as negative magnetic resonance contrast agents. Moreover, nanoparticles reduced the peritumoral edema confirming the therapeutic potency of synthesized conjugates. SPION–IL-1Ra nanoparticles have an anti-edemal effect when administered through a clinically relevant route in animals with glioma. The SPION–IL-1Ra could be a candidate for theranostic approach in neuro-oncology both for diagnosis of brain tumors and management of peritumoral edema.     

Inhibitory effect of suramin in rat models of angiogenesis in vitro and in vivo

The aim of the present study was to test the ability of the chemotherapeutic agent suramin to inhibit angiogenesis in experimental models in vitro and in vivo. In the culture of rat aortic rings on fibronectin, suramin dose-dependently inhibited vascular cell growth, achieving the maximal effect (mean − 88% versus controls, P < 0.05) at 400 μg/ml. Image analysis showed that suramin could inhibit microvessel sprouting in fibrin from rat aortic rings as evaluated by the ratio between the cellular area and the mean gray value of the sample (sprouting index); suramin at 50 μg/ml significantly reduced the sprouting index from the control value of 0.35 ± 0.04 to 0.14 ± 0.02 mm²/gray level (P < 0.05). Likewise, the area occupied by cells was 19.2 ± 1.8 mm² as compared with 41.8 ± 4.2 mm² in controls (P < 0.05). In the rat model of neovascularization induced in the cornea by chemical injury, suramin at 1.6 mg/eye per day reduced the length of blood vessels (0.7 ± 0.1 mm as compared with 1.5 ± 0.1 mm in controls, P < 0.05). In the same model the ratio between the area of blood vessels and the total area of the cornea (area fraction score) was decreased by suramin from 0.19 ± 0.02 in controls to 0.03 ± 0.003 (P < 0.05). Suramin given i.p. at 30 mg/kg per day markedly inhibited the neovascularization induced in the rat mesentery by compound 48/80 or conditioned medium from cells secreting the angiogenic protein fibroblast growth factor-3 (FGF-3). The area fraction score in control rats treated with compound 48/80 was 0.31 ± 0.03, and this was reduced to 0.07 ± 0.01 by suramin (P < 0.05). After i.p. administration of FGF-3 the area fraction score was reduced by suramin from 0.29 ± 0.03 to 0.05 ± 0.01 (P < 0.05). These results provide evidence that suramin exerts inhibitory effects on angiogenesis in both in vitro and in vivo models. Received: 9 January 1998 / Accepted: 29 June 1998     

Fluorescence-guided resection of metastatic brain tumors using a 5-aminolevulinic acid-induced protoporphyrin IX: pathological study

We performed a pathological study to identify the locus of production of protoporphyrin IX (PPIX) in human metastatic brain tumors. Patients with metastatic brain tumors (n = 11) received 1 g of 5-aminolevulinic acid (5-ALA) perorally 2 h before undergoing surgery. The target region was exposed to laser light with a peak wavelength of 405 ± 1 nm and an output of 40 mW. Tissue samples from the tumor bulk and surrounding areas were examined by histological and fluorescence methods. Of the 11 tumors, 9 manifested PPIX fluorescence in the tumor bulk and peritumoral brain tissue. Our findings indicate that PPIX fluorescence can be observed in peritumoral edematous areas that are free of neoplastic cells, because PPIX produced by neoplastic cells leaks into the surrounding edematous area.     

Rat Brain Tumor Models to Assess the Efficacy of Boron Neutron Capture Therapy: A Critical Evaluation

Development of any therapeutic modality can be facilitated by the use of the appropriate animal models to assess its efficacy. This report primarily will focus on our studies using the F98 and 9L rat glioma models to evaluate the effectiveness of boron neutron capture therapy (BNCT) of brain tumors. Following intracerebral implantation the biological behavior of each tumor resembles that of human high grade gliomas in a number of ways. In both models, glioma cells were implanted intracerebrally into syngeneic Fischer rats and 10–14 days later BNCT was initiated at the Brookhaven National Laboratory Medical Research Reactor. Two low molecular weight (M _r < 210Da) ¹⁰B-containing drugs, boronophenylalanine (BPA) and/or sodium borocaptate (BSH) were used as capture agents, either alone or in combination with each other. The 9L gliosarcoma, which has been difficult to cure by means of either chemo- or radiotherapy alone, was readily curable by BNCT. The best survival data were obtained using BPA at a dose of 1200mg/kg (64.8mg ¹⁰B), administered intraperitoneally (i.p.), with a 100% survival rate at 8 months. In contrast, the F98 glioma has been refractory to all therapeutic modalities. Tumor bearing animals, which had received 500mg/kg (27mg ¹⁰B) of BPA, or an equivalent amount of BSH i.v., had mean survival time (MST) of 37 and 33 days, respectively, compared to 29 days for irradiated controls. The best survival data with the F98 glioma model were obtained using BPA + BSH in combination, administered intra-arterially via the internal carotid artery (i.c.) with hyperosmotic mannitol induced blood–brain barrier disruption (BBB-D). The MST was 140 days with a cure rate of 25%, compared to a MST of 73 days with a 5% cure rate without BBB-D, and 41 days following i.v. administration of both drugs. A modest but significant increase in MST also was observed in rats that received intracarotid (i.c.) BPA in combination with Cereport (RMP-7), which produced a pharmacologically mediated opening of the BBB. Studies also have been carried out with the F98 glioma to determine whether an X-ray boost could enhance the efficacy of BNCT, and it was shown that there was a significant therapeutic gain. Finally, molecular targeting of the epidermal growth factor receptor (EGFR) has been investigated using F98 glioma cells, which had been transfected with the gene encoding EGFR and, intratumoral injection of boronated EGF as the delivery agent, followed by BNCT. These studies demonstrated that there was specific targeting of EGFR and provided proof of principle for the use of high molecular weight, receptor targeting-boron delivery agents. Finally, a xenograft model for melanoma metastatic to the brain has been developed using a human melanoma (MRA27), stereotactically implanted into the brains of nude rats, and these studies demonstrated that BNCT either cured or significantly prolonged the survival of tumor-bearing rats. It remains to be determined, which, if any, of these experimental approaches will be translated into clinical studies. Be that as it may, rat brain tumor models already have made a significant contribution to the design of clinical BNCT protocols, and should continue to do so in the future.     

Convection enhanced delivery of carboranylporphyrins for neutron capture therapy of brain tumors

Boron neutron capture therapy (BNCT) is based on the nuclear capture and fission reactions that occur when non-radioactive ¹⁰B is irradiated with low energy thermal neutrons to produce α-particles (¹⁰B[n,α]⁷Li). Carboranylporphyrins are a class of substituted porphyrins containing multiple carborane clusters. Three of these compounds, designated H₂TBP, H₂TCP, and H₂DCP, have been evaluated in the present study. The goals were two-fold. First, to determine their biodistribution following intracerebral (i.c.) administration by short term (30 min) convection enhanced delivery (CED) or sustained delivery over 24 h by Alzet™ osmotic pumps to F98 glioma bearing rats. Second, to determine the efficacy of H₂TCP and H₂TBP as boron delivery agents for BNCT in F98 glioma bearing rats. Tumor boron concentrations immediately after i.c. pump delivery were high and they remained so at 24 h. The corresponding normal brain concentrations were low and the blood and liver concentrations were undetectable. Based on these data, therapy studies were initiated at the Massachusetts Institute of Technology (MIT) Research Reactor (MITR) with H₂TCP and H₂TBP 24 h after CED or pump delivery. Mean survival times (MST) ± standard deviations of animals that had received H₂TCP or H₂TBP, followed by BNCT, were of 35 ± 4 and 44 ± 10 days, compared to 23 ± 3 and 27 ± 3 days, respectively, for untreated and irradiated controls. However, since the tumor boron concentrations of the carboranylporphyrins were 3–5× higher than intravenous (i.v.) boronophenylalanine (BPA), we had expected that the MSTs would have been greater. Histopathologic examination of brains of BNCT treated rats revealed that there were large numbers of porphyrin-laden macrophages, as well as extracellular accumulations of porphyrins, indicating that the seemingly high tumor boron concentrations did not represent the true tumor cellular uptake. Nevertheless, our data are the first to show that carboranyl porphyrins can be used as delivery agents for BNCT of an experimental brain tumor. Based on these results, we now are in the process of synthesizing and evaluating carboranylporphyrins that could have enhanced cellular uptake and improved therapeutic efficacy.     

UV exposure inhibits intestinal tumor growth and progression to malignancy in intestine‐specific Apc mutant mice kept on low vitamin D diet

Mortality from colorectal cancer increases with latitude and decreases with ambient UV radiation. We investigated whether moderate UV dosages could inhibit intestinal tumor development and whether this corresponded with UV‐induced vitamin D. FabplCre;Apc^15lox/+ mice, which develop intestinal tumors, and their parents were put on a vitamin D‐deficient diet. Next to a control group, one group was vitamin D supplemented and another one group was daily UV irradiated from 6 weeks of age. Vitamin D statuses after 6 weeks of treatment were markedly increased: mean ± SD from 7.7 ± 1.9 in controls to 75 ± 15 nmol/l with vitamin D supplementation (no gender difference), and to 31 ± 13 nmol/l in males and 85 ± 17 nmol/l in females upon UV irradiation. The tumor load (area covered by tumors) at 7.5 months of age was significantly reduced in both the vitamin D‐supplemented group (130 ± 25 mm², p = 0.018) and the UV‐exposed group (88 ± 9 mm², p < 0.0005; no gender differences) compared to the control group (202 ± 23 mm²). No reductions in tumor numbers were found. Only UV exposure appeared to reduce progression to malignancy (p = 0.014). Our experiments clearly demonstrate for the first time an inhibitory effect of moderate UV exposure on outgrowth and malignant progression of primary intestinal tumors, which at least in part can be attributed to vitamin D.     

Convection enhanced delivery of boronated EGF as a molecular targeting agent for neutron capture therapy of brain tumors

In the present study, we have evaluated a boronated dendrimer-epidermal growth factor (BD-EGF) bioconjugate as a molecular targeting agent for boron neutron capture therapy (BNCT) of the human EGFR gene-transfected F98 rat glioma, designated F98_EGFR. EGF was chemically linked to a heavily boronated polyamidoamine dendrimer (BD) by means of the heterobifunctional reagent, mMBS. Biodistribution studies were carried out at 6 h and 24 h following intratumoral (i.t.) injection or intracerebral (i.c.) convection enhanced delivery (CED) of ¹²⁵I-labeled or unlabeled BD-EGF (40 μg ¹⁰B/10 μg EGF) to F98 glioma bearing rats. At 24 h. there was 43% more radioactivity in EGFR(+) tumors following CED compared to i.t. injection, and a doubling of the tumor boron concentration (22.3 μg/g vs. 11.7 μg/g). CED of BD-EGF resulted in a 7.2× increase in the volume of distribution within the infused cerebral hemisphere and a 1.9× increase in tumor uptake of BD-EGF compared with i.t. injection. Based on these favorable biodistribution data, BNCT was carried out at the Massachusetts Institute of Technology nuclear reactor 14 days following i.c. tumor implantation and 24 h. after CED of BD-EGF. These animals had a MST of 54.1 ± 4.7 days compared to 43.0 ± 2.8 days following i.t. injection. Rats that received BD-EGF by CED in combination with i.v. boronophenylalanine (BPA), which has been used in both experimental and clinical studies, had a MST of 86.0 ± 28.1 days compared to 39.8 ± 1.6 days for i.v. BPA alone (P < 0.01), 30.9 ± 1.4 days for irradiated controls and 25.1 ± 1.0 days for untreated controls (overall P < 0.0001). These data have demonstrated that the efficacy of BNCT was significantly increased (P < 0.006), following i.c CED of BD-EGF compared to i.t injection, and that the survival data were equivalent to those previously reported by us using the boronated anti-human-EGF mAb, C225 (cetuximab).     

Tryptophan PET in pretreatment delineation of newly-diagnosed gliomas: MRI and histopathologic correlates

Pretreatment delineation of infiltrating glioma volume remains suboptimal with current neuroimaging techniques. Gadolinium-enhanced T1-weighted (T1-Gad) MR images often underestimate the true extent of the tumor, while T2-weighted images preferentially highlight peritumoral edema. Accumulation of α-[¹¹C]methyl-l-tryptophan (AMT) on positron emission tomography (PET) has been shown in gliomas. To determine whether increased uptake on AMT–PET would detect tumor-infiltrated brain tissue outside the contrast-enhancing region and differentiate it from peritumoral vasogenic edema, volumes and spatial concordance of T1-Gad and T2 MRI abnormalities as well as AMT–PET abnormalities were analyzed in 28 patients with newly-diagnosed WHO grade II–IV gliomas. AMT-accumulating grade I meningiomas were used to define an AMT uptake cutoff threshold that detects the tumor but excludes peri-meningioma vasogenic edema. Tumor infiltration in AMT-accumulating areas was studied in stereotactically-resected specimens from patients with glioblastoma. In the 28 gliomas, mean AMT–PET-defined tumor volumes were greater than the contrast-enhancing volume, but smaller than T2 abnormalities. Volume of AMT-accumulating tissue outside MRI abnormalities increased with higher tumor proliferative index and was the largest in glioblastomas. Tumor infiltration was confirmed by histopathology from AMT-positive regions outside contrast-enhancing glioblastoma mass, while no or minimal tumor cells were found in AMT-negative specimens. These results demonstrate that increased AMT accumulation on PET detects glioma-infiltrated brain tissue extending beyond the contrast-enhanced tumor mass. While tryptophan uptake is low in peritumoral vasogenic edema, AMT–PET can detect tumor-infiltrated brain outside T2-lesions. Thus, AMT–PET may assist pretreatment delineation of tumor infiltration, particularly in high-grade gliomas.     

Regional administration of natural killer cells in a rat hepatic metastasis model results in better tumor infiltration and anti-tumor response than systemic administration

A syngeneic rat liver metastasis model, the CC531 colon carcinoma cell line in Wag rats, was used to study the homing properties and anti-tumor effects of adoptively transferred, interleukin-2 (IL-2)-activated, cultured natural killer (A-NK) cells. To identify the route of administration that gives the highest tumor infiltration, 1.5 × 10⁸ A-NK cells were dyed with fluorescent rhodamine and injected via 4 different routes into rats, bearing subcapsularly induced (day 10) liver metastases. The routes chosen were: jugular vein, portal vein, hepatic artery and directly into the peritoneal cavity (i.p). The rats were sacrificed 20 hr after administration of A-NK cells. The highest (p < 0.05) infiltration of tumors by A-NK cells was found both at the tumor border and in the tumor center after injection via the hepatic artery: 65 ± 7 A-NK cells/mm² at the tumor border and 26 ± 14 A-NK cells/mm² in the center of the tumor (jugular vein infusion: 32 ± 10 and 9 ± 5 A-NK cells/mm², respectively; portal vein infusion: 36 ± 13 and 7 ± 4 A-NK cells/mm², respectively). No A-NK cells were detected in the liver after i.p. injection. Rats bearing day 5 tumors were injected with 1.5 × 10⁸ A-NK cells via the hepatic artery or via the jugular vein (n = 5 and n = 6 respectively). Regional administration of A-NK cells via the hepatic artery resulted in a significant (p < 0.05) lower weight (35 ± 23 mg) of tumors than did systemic administration (70 ± 10 mg). Our results suggest that both the level of tumor infiltration by adoptively transferred A-NK cells and the therapeutic outcome depend on the route of administration. Int. J. Cancer 75:233–238, 1998. © 1998 Wiley-Liss, Inc.     

Tumor-specific targeting of sodium borocaptate (BSH) to malignant glioma by transferrin-PEG liposomes: a modality for boron neutron capture therapy

Object Boron neutron capture therapy (BNCT) requires selective delivery of a high concentration of boron-10 (¹⁰B) to tumor tissue. To improve a drug delivery in BNCT, we devised transferrin-conjugated polyethylene-glycol liposome encapsulating sodium borocaptate (TF-PEG-BSH). Methods ¹⁰B concentrations of U87Δ human glioma cells from three boron delivery systems (BDS) (bare BSH, PEG-BSH, and TF-PEG-BSH) were analyzed in vitro by use of inductively coupled plasma-atomic emission spectrometry (ICP-AES). A colony-forming assay (CFA) was performed using this cell line with the three BDS and neutron irradiation. Subcellular localization of BSH in tumor cells was analyzed in vitro by immunocytochemistry using monoclonal antibodies raised for BSH. Brain tumor models were made and the ¹⁰B concentrations of the tumor, blood, and normal brain from each BDS were analyzed in vivo by use of ICP-AES. The tumor-to-blood and the tumor-to-normal brain ratios were evaluated. BNCT for the brain tumor models was performed and survival was analyzed. Results In CFA, TF-PEG-BSH showed the most prominent effects by neutron irradiation among the three BDS. TF-PEG-BSH showed highly selective and highly efficient ¹⁰B delivery in tumor tissue. The survival rate in the treatment experiment was best in the TF-PEG-BSH group. Immunocytochemically, TF-PEG-BSH delivered BSH efficiently not only into the cytoplasm but also into the nucleus. Conclusion TF-PEG-BSH is a potent BDS for BNCT not only in terms of delivering a high concentration of ¹⁰B into tumor tissue, but also the selective delivery of ¹⁰B into the tumor cells.     

磁共振扩散张量成像定量参数对脑胶质瘤分级的诊断价值

目的:探讨磁共振扩散张量成像（diffusion tensor imaging，DTI）定量参数，是否可以对脑胶质瘤进行分级。方法:选取抚矿总医院2015年2月至2017年11月，经病理证实的脑胶质瘤患者60例，依据WHO肿瘤分级标准，分为高级别组（A组）27例，低级别组（B组）33例，分别给予患者磁共振平扫、增强扫描及DTI，观察图像信号变化规律，并测量DTI定量参数FA值与ADC值。结果:ADC值组间比较，A组病人瘤体和瘤周水肿带的ADC值，与B组病人瘤体和瘤周水肿带的ADC值对比，差异有统计学意义（P<0.05）。A、B组内对比，周围水肿带ADC值大于瘤体ADC值，差异有统计学意义（P<0.05）。FA值组间对比，A、B两组肿瘤主体和瘤体周围水肿带对比，差异无统计学意义（P>0.05）。A、B组内对比，瘤周水肿带的FA值大于肿瘤主体FA值，差异有统计学意义（P<0.05）。结论:DTI定量参数可以对脑胶质瘤进行分级，并获得满意效果。