Polyamines in human brain tumors

Summary Polyamine levels have been studied in brain tumor patients. We focused our study on the relationship between tumor, cerebrospinal fluid (CSF) and red blood cell (RBC) polyamine levels. Our results are the following: (1) Polyamine levels in CSF are consistently increased, whatever the histological type may be. (2) The highest tumoral concentrations are found in medulloblastomas. (3) In glioblastomas, the RBC spermidine levels are higher than in the other types of tumors and there is a highly significant correlation between the spermidine/spermine ratio in tumor and RBC. Therefore, RBC polyamine determinations might be of clinical interest in the monitoring of patients with glioblastomas.Supported in part by Research Grant of Ligue Nationale Française Contre le Cancer, Fondation pour la Recherche Médicale Française, Fondation Jean Langlois.     

Mechanisms ofvascularization inmurine models ofprimary andmetastatic tumor growth

Directed capillary ingrowth has long been considered synonymous with tumor vascularization. However, the vascu?lature of primary tumors and metastases is not necessarily formed by endothelial cell sprouting; instead, malignant tumors can acquire blood vessels via alternative vascularization mechanisms, such as intussusceptive microvascular growth, vessel co?option, and glomeruloid angiogenesis. Importantly, in response to anti?angiogenic therapies, malig?nant tumors can switch from one vascularization mechanism to another. In this article, we brielfy review the biological features of these mechanisms and discuss on their signiifcance in medical oncology.     

Radiotherapy of primary brain stem tumors

This paper presents results of treatment for 80 patients with primary brain stem tumors who were seen at McGill University Hospitals from 1960–1975. A large proportion of the patients were under 15 years old. The majority of pretreatment diagnoses were based on neuroradiologic procedures. The correlation of these procedures in histologically verified cases is high. Glioblastoma comprised 38.7 % of the histologically proven cases. Radiotherapy was the main modality of the treatment. Of the patients who received over 5000 rod, 44/63 (39.8°10) survived at 3 years, 34.5 % at 5 years and 28.4 % at 10 years. This result is similar to that in Bouchard's series which analyzed the cases from the same source prior to this series. The initial response to treatment was beneficial in the majority of patients and this early response appears to be a dependable prognostic parameter.     

Therapeutic application of noncytotoxic molecular targeted therapy in gliomas: growth factor receptors and angiogenesis inhibitors

Growth factor receptors and angiogenesis play major roles in the oncogenesis of gliomas. Over the last several years, several noncytotoxic molecular targeted therapies have been developed against growth factor receptors and tumor angiogenesis. In gliomas, two main anti-growth factor receptor strategies have been evaluated in phase I/II clinical trials: (a) small molecule tyrosine kinase inhibitors (TKIs) and (b) monoclonal antibodies that target growth factors or growth factor receptors other than vascular endothelial growth factor (VEGF). Up to now, few glioma patients have responded to small TKIs (0%-14%) or monoclonal antibodies (three case reports) delivered as a single agent. Greater doses, combined therapies, as well as the identification of molecular biomarkers predictive of response and resistance are important in order to optimize drug delivery and improve efficacy. Antiangiogenic therapies are promising for the treatment of gliomas. Thalidomide and metronomic chemotherapy were the first antiangiogenic strategies evaluated, but they have shown only modest activity. Recent studies of bevacizumab, an anti-VEGF antibody, and irinotecan, a topoisomerase I inhibitor, have demonstrated a high response rate, suggesting that targeted antiangiogenic therapies may play a significant role in the management of high-grade gliomas in the future. However, the toxicity profiles of these agents are not fully defined and the radiological evaluation of possible tumor response is challenging. Clinical evaluation of several VEGF receptor TKIs is currently ongoing; one of these inhibitors, cediranib, has already demonstrated interesting activity as a single agent. The integrin inhibitor cilengitide represents another promising strategy.     

c-jun基因沉默对放射抗拒鼻咽癌裸鼠移植瘤生长及血管生成的影响

目的 探讨c-jun基因沉默对人鼻咽癌放射抗拒CNE-2R细胞裸鼠移植瘤生长及血管生成的影响。方法 用携带shRAN慢病毒载体感染CNE-2R细胞以沉默c-jun基因,构建c-jun-shRNA-CNE-2R细胞组（c-jun-shRNA组）以及阴性对照NC-shRNA-CNE-2R细胞组（NC组）,以CNE-2R细胞为空白对照组,采用Western blot 检测3组细胞中血管内皮生长因子（vascular endothelial growth factor,VEGF）蛋白的表达水平。构建裸鼠模型,观察3组细胞裸鼠皮下种植瘤生长曲线及体积;采用免疫组化法检测移植瘤组织中VEGF、CD34的表达,并检测组织内微血管密度（microvessel density,MVD）。结果 Western blot 结果显示,c-jun-shRNA组细胞VEGF蛋白表达较NC组及空白对照组明显下调（P<0.05）。裸鼠模型实验中,c-jun-shRNA组移植瘤体积为（720.85±72.10） mm³,质量为（0.42±0.04）g,MVD为11.69±3.30;NC组移植瘤体积为（1 196.81±90.69） mm³,质量为（0.80±0.08）g,MVD为32.56±7.33;空白对照组移植瘤体积为（1 203.76±100.42） mm³,质量为（0.83±0.05）g,MVD为35.45±4.87;c-jun-shRNA组种植瘤体积、质量、MVD较NC组和空白对照组低（P<0.05）。免疫组化检测结果显示,移植瘤组织中VEGF蛋白表达c-jun-shRNA组呈弱阳性,NC组及空白对照组组均呈强阳性。结论 c- jun基因沉默可抑制放射抗拒性鼻咽癌移植瘤生长及血管生成。     

Targeting SRC in glioblastoma tumors and brain metastases: rationale and preclinical studies

Glioblastoma (GBM) is an extremely aggressive, infiltrative tumor with a poor prognosis. The regulatory approval of bevacizumab for recurrent GBM has confirmed that molecularly targeted agents have potential for GBM treatment. Preclinical data showing that SRC and SRC-family kinases (SFKs) mediate intracellular signaling pathways controlling key biologic/oncogenic processes provide a strong rationale for investigating SRC/SFK inhibitors, e.g., dasatinib, in GBM and clinical studies are underway. The activity of these agents against solid tumors suggests that they may also be useful in treating brain metastases. This article reviews the potential for using SRC/SFK inhibitors to treat GBM and brain metastases.     

Immunohistochemical expression of E-cadherin in metastatic brain tumors

The adhesion molecule E-cadherin has been shown to influence malignant transformation of tumors, including local and distant metastases. We examined the expression of E-cadherin to determine its relationship to the development of metastasis in metastatic brain tumors. Immunohistochemistry for E-cadherin and Ki-67 was carried out in 76 formalin-fixed, paraffin-embedded archival specimens of metastatic brain tumors and in 14 corresponding available primary tumors from patients who received treatment for metastatic brain tumors. The primary tumors were mainly lung cancers (51.3%), followed by gastrointestinal tumors (28.9%). E-cadherin was expressed in 62 (81.5%) of 76 cases examined. In metastatic adenocarcinomas, a consistent tendency for E-cadherin expression was noted, regardless of the degree of differentiation or the extent of spread of the disease (P=0.4). There was a direct correlation between E-cadherin expression and high MIB-1 index in all metastatic brain tumors (P=0.0007). Pairwise analysis in 14 primary tumors and the corresponding metastatic specimens revealed high E-cadherin and MIB-1 staining in metastatic brain tumors. These results provide a unique association between E-cadherin, systemic metastasis, and proliferation potential in metastatic brain tumors.     

Angiogenesis inhibitor DC101 delays growth of intracerebral glioblastoma but induces morbidity when combined with irradiation

The combination of irradiation with angiogenic inhibition is increasingly being investigated for treatment of glioblastoma multiforme (GBM). We investigated whether vascular endothelial growth factor receptor-2 (VEGFR-2) inhibitor DC101 affects morbidity and tumor growth in irradiated and non-irradiated intracerebral GBM-bearing mice, controlled with sham treatments. End-points were toxicity, morbidity and histology. Irradiation either or not combined, reduced tumor size strongly, whereas DC101 mono-treatment reduced tumor size by 64%. Irradiation delayed morbidity from 5.8 weeks in sham-treated mice to 10.3 weeks. Morbidity after combined treatment occurred after 5.9 weeks. Treatment with angiogenesis inhibitor DC101 delays tumor growth but it induces morbidity, by itself or combined with irradiation.     

Clinical biomarkers of angiogenesis inhibition

INTRODUCTION: An expanding understanding of the importance of angiogenesis in oncology and the development of numerous angiogenesis inhibitors are driving the search for biomarkers of angiogenesis. We review currently available candidate biomarkers and surrogate markers of anti-angiogenic agent effect. DISCUSSION: A number of invasive, minimally invasive, and non-invasive tools are described with their potential benefits and limitations. Diverse markers can evaluate tumor tissue or biological fluids, or specialized imaging modalities. CONCLUSIONS: The inclusion of these markers into clinical trials may provide insight into appropriate dosing for desired biological effects, appropriate timing of additional therapy, prediction of individual response to an agent, insight into the interaction of chemotherapy and radiation following exposure to these agents, and perhaps most importantly, a better understanding of the complex nature of angiogenesis in human tumors. While many markers have potential for clinical use, it is not yet clear which marker or combination of markers will prove most useful.     

Chemokines in tumor angiogenesis and metastasis

Chemokines are a large group of low molecular weight cytokines that are known to selectively attract and activate different cell types. Although the primary function of chemokines is well recognized as leukocyte attractants, recent evidences indicate that they also play a role in number of tumor-related processes, such as growth, angiogenesis and metastasis. Chemokines activate cells through cell surface seven trans-membranes, G-protein-coupled receptors (GPCR). The role played by chemokines and their receptors in tumor pathophysiology is complex as some chemokines favor tumor growth and metastasis, while others may enhance anti-tumor immunity. These diverse functions of chemokines establish them as key mediators between the tumor cells and their microenvironment and play critical role in tumor progression and metastasis. In this review, we present some of the recent advances in chemokine research with special emphasis on its role in tumor angiogenesis and metastasis.     

Quantification of dispersion of Gd-DTPA from the initial area of enhancement into the peritumoral zone of edema in brain tumors

To evaluate Gd-DTPA contrast enhancement of brain tumors over time and to describe the dispersion of contrast into the zone of peritumoral edema. We performed MR imaging with a dose of 0.4 mmol Gd-DTPA/kg on eleven patients diagnosed with 5 different supratentorial tumors. MR imaging was done at five intervals between 5 min and 6 h. The change in zone of enhancement was measured for each time point, and a linear measurement was made of the furthest dispersion of contrast from the original volume of enhancement. An increase in the zone of enhancement over time was seen for all tumors; the average increase in volume of contrast was 14.76 ± 3.35 cm³ (mean ± standard deviation). The largest changes in the zone of contrast enhancement, 18.6 ± 4.63 cm³, were seen in glioblastoma multiforme. The expansion of contrast enhancement assumed the morphology of the surrounding edema. The dispersion of Gd-DTPA over time into the zone of peritumoral edema is a potential source of error in clinical settings when there is a delay between Gd-DTPA injection and scanning.     

Differential dependency of human cancer cells on vascular endothelial growth factor-mediated autocrine growth and survival

Analysis using the public microarray database Gene Expression Omnibus indicates significantly higher mRNA expression of VEGF and VEGFRs in colorectal cancer and high grade astrocytoma but not in hepatocellular carcinoma compared to normal tissue. Human malignant astrocytoma cell lines (U251-MG and U373-MG) and HT-1080 fibrosarcoma cells expressed relatively higher levels of VEGF and VEGFRs compared to hepatocellular and colorectal cancer cell lines. Administration of exogenous VEGF-A induced cell growth in a dose-dependent fashion in astrocytoma and fibrosarcoma cells but not in colorectal and hepatocellular cancer cells. The blockade of VEGF inhibited cell survival only in U251-MG, U373-MG and HT-1080 cells. These results collectively suggest the role of autocrine VEGF signaling in various cancer cells and provide a basis for the variable clinical responses to antiangiogenic therapy observed in different types of malignancies.     

Adenovirus-mediated p53 gene delivery potentiates the radiation-induced growth inhibition of experimental brain tumors

Patients with malignant gliomas continue to have very poor prognosis even after surgical resection, radiation and chemotherapy. Because these tumors often have alterations in the p53 tumor suppressor gene, which plays a key role in the cellular response to DNA damaging agents, we investigated the role of p53 gene therapy in conjunction with ionizing radiation in a rat brain tumor model. Exposure of cultured rat 9L gliosarcoma cells, which contain a mutant p53 gene, to a recombinant adenovirus-vector bearing the wild-type p53 gene (Adp53), induced apoptosis within 24 hours. Although ionizing radiation had no additional effect on apoptosis within this time frame, it caused G₁ arrest in non-apoptotic cells after Adp53 therapy. In contrast, wild-type 9L cells demonstrated little G₁ arrest after X-irradiation. When animals bearing brain tumors were irradiated after intratumoral Adp53 injections, more than 85% reduction in tumor size was noted. Moreover, the group of rats receiving both radiation and Adp53 therapy had a significant increase in survival as compared to animals receiving either therapy alone. These results support the use of p53 gene therapy as an adjunct to radiation in treatment of malignant brain tumors.     

Aquaporins in tumor growth and angiogenesis

The aquaporins (AQPs) are a family of transmembrane water channel proteins widely distributed and play a major role in transcellular and transepithelial water movement. Moreover, recent evidence indicates that AQPs may be involved in cell migration and angiogenesis. This review article summarizes literature data concerning the involvement of AQPs in tumor growth, angiogenesis and metastatic process and suggest a potential therapeutic approach by antagonizing their biological activity.     

Intratumoral COX‐2 inhibition enhances GM‐CSF immunotherapy against established mouse GL261 brain tumors

Immunotherapy has shown effectiveness against experimental malignant brain tumors, but the clinical results have been less convincing most likely due to immunosuppression. Prostaglandin E₂ (PGE₂) is the key immunosuppressive product of cyclooxygenase‐2 (COX‐2) and increased levels of PGE₂ and COX‐2 have been shown in several tumor types, including brain tumors. In the current study, we report enhanced cure rate of mice with established mouse GL261 brain tumors when immunized with granulocyte macrophage‐colony stimulating factor (GM‐CSF) secreting tumor cells and simultaneously treated with the selective COX‐2 inhibitors parecoxib systemically (5 mg/kg/day; 69% cure rate) or valdecoxib intratumorally (5.3 µg/kg/day; 63% cure rate). Both combined therapies induced a systemic antitumor response of proliferating CD4⁺ and CD8⁺ T cells, and further analysis revealed T helper 1 (T_h1) cell supremacy. The GL261 tumor cell line produced low levels of PGE₂ in vitro, and co‐staining at the tumor site demonstrated that a large fraction of the COX‐2⁺ cells were derived from CD45⁺ immune cells and more specifically macrophages (F4/80⁺), indicating that tumor‐infiltrating immune cells constitute the primary source of COX‐2 and PGE₂ in this model. We conclude that intratumoral COX‐2 inhibition potentiates GM‐CSF immunotherapy against established brain tumors at substantially lower doses than systemic administration. These findings underscore the central role of targeting COX‐2 during immunotherapy and implicate intratumoral COX‐2 as the primary target.     

Chemoradiotherapy for brain tumors: current status and perspectives

Brain tumors growing in the parenchyma of the brain infiltrate diffusely, and the role of surgery is restricted to maximal tumor-bulk removal. Residual tumor cells beyond the surgical margin are not killed by conventional radiation therapy with 60Gy. Many clinical trials delivering chemotherapy during radiation therapy and after radiation therapy have been performed, but the results remain poor. Here the author reviews the current treatments of gliomas, malignant lymphomas, medulloblastomas, and germ cell tumors, and their results.     

血管内皮生长因子在胶质瘤中的表达

目的：研究人脑胶质瘤组织中血管内皮生长因子mRNA的表达，同时分析肿瘤间质血管增生的情况，并探讨两者之间的关系。方法：采用半定量逆转录－聚合酶链反应（RT－PCR）方法，对49例人脑胶质瘤手术切除标本，U251等3株胶质瘤细胞以及12例脑外伤内减压术中得到的正常脑组织检测了VEGF mRNA表达水平水平。另外，用免疫组化SP法对组织中的微血管密度（MVD）进行了分析。结果：胶质瘤组织中的VEGF mRNA表达水平达65．3％，随着病理分级的提高其表达水平有升高趋势，HUVEC及3株胶质瘤细胞亦表达水平较高，而正常脑组织表达水平及表达率较低，胶质瘤中的微血管密度（MVD）与胶质瘤级别之间有等级相关性，VEGF mRNA表达同MVD呈正相关。结论：VEGF、MVD对胶质瘤的恶性质瘤的恶性生物学行为的评估有重要意义，VEGF的高表达导致肿瘤组织血管增生，在胶质瘤侵袭过程中发挥重要作用。     

Ultrastructural analysis of brain tumors using collagen gel culture

In an attempt to investigate the tumor type-specific ultrastructure of cultured brain tumors, a collagen gel culture was utilized instead of the conventional monolayer culture. To avoid intermingling of the normal brain cells, tumors with a clear margin and a portion typical of invasive tumors were sampled. The tumors were minced, and small fragments were prepared and embedded in the collagen gel in an aseptic manner. Tumors were observed on a daily basis under a phase contrast microscope. When sprouting of the tumor cells from a tumor fragment was confirmed, the samples were fixed with 2.5% glutaraldehyde and then processed for electron microscopy. Ultrastructurally, meningioma has been shown to form a whorl-like structure. The cell processes have a complex interrelationship, but this phenomenon cannot be regarded as the so-called interdigitation. A basement membrane was formed surrounding the tumor cell processes facing the collagen gel in two ependymomas. Lipid droplets were contained in great numbers inside a chordoma cell. These findings suggest the usefulness of collagen gel culture in analyzing the tumor type-specific ultrastructure of cultured brain tumors, and possibly in studying cellular differentiation.     

Selective cancer-germline gene expression in pediatric brain tumors

Cancer-germline genes (CGGs) code for immunogenic antigens that are present in various human tumors and can be targeted by immunotherapy. Their expression has been studied in a wide range of human tumors in adults. We measured the expression of 12 CGGs in pediatric brain tumors, to identify targets for therapeutic cancer vaccines. Real Time PCR was used to quantify the expression of genes MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A4, MAGE-A6, MAGE-A10, MAGE-A12, MAGE-C2, NY-ESO-1 and GAGE-1,2,8 in 50 pediatric brain tumors of different histological subtypes. Protein expression was examined with immunohistochemistry. Fifty-five percent of the medulloblastomas (n = 11), 86% of the ependymomas (n = 7), 40% of the choroid plexus tumors (n = 5) and 67% of astrocytic tumors (n = 27) expressed one or more CGGs. Immunohistochemical analysis confirmed qPCR results. With exception of a minority of tumors, the overall level of CGG expression in pediatric brain tumors was low. We observed a high expression of at least one CGG in 32% of the samples. CGG-encoded antigens are therefore suitable targets in a very selected group of pediatric patients with a brain tumor. Interestingly, glioblastomas from adult patients expressed CGGs more often and at significantly higher levels compared to pediatric glioblastomas. This observation is in line with the notion that pediatric and adult glioblastomas develop along different genetic pathways.