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Biomedical subjects

Gregory N Fuller

Publications and source records attributed to Gregory N Fuller.

At least 19 recordsLinked to original sources
PubMed2003

Insulin-like growth factor binding protein 2 enhances glioblastoma invasion by activating invasion-enhancing genes.

Comparison of gene expressing profiles between gliomas with different grades revealed frequent overexpression of insulin-like growth factor binding protein 2 (IGFBP2) in glioblastoma (GBM), the most advanced stage of glioma. To determine whether IGFBP2 is involved in the proliferative and invasive nature of GBM, we established stable SNB19 GBM cell lines that overexpress IGFBP2. Although there was no marked difference in the cell growth between IGFBP2 overexpressing SNB19(BP2) lines when compared with the control cells, these clones showed significantly increased invasive rates when compared with the parental or vector transfected SNB19 cells. Total RNAs from controls and SNB19(BP2) clones were used for microarray analysis to detect IGFBP2-mediated alterations in gene expression. When compared with parental or vector-transfected control cells, SNB19(BP2) cells consistently showed 3-5-fold increase in the expression of matrix metalloproteinase-2 (MMP-2) as well as other invasion related genes. Increased MMP-2 expression in SNB19(BP2) cells was subsequently confirmed by real time reverse-transcription PCR, Western blotting, and gelatin zymography. Furthermore, consistent with increased MMP-2 expression in SNB19(BP2) cells, transient transfection of a MMP-2 promoter/luciferase reporter also resulted in 3-6-fold higher luciferase activity in SNB19(BP2) cells than in parental or vector-transfected control cells. Finally, tissue microarray analysis of 68 GBM tissue specimens showed a significant correlation between the overexpression of IGFBP2 and elevated MMP-2 expression. Taken together, our data provide evidence that IGFBP2 contributes to glioma progression in part by enhancing MMP-2 gene transcription and in turn tumor cell invasion.

Gene Expression Regulation, Neoplastic↗
PubMed2003

Gliomatosis cerebri: improved outcome with radiotherapy.

PURPOSE: Gliomatosis cerebri is a rare, diffuse involvement of the central nervous system by a malignant glioma that permeates the brain extensively without destroying the neural architecture and involves more than two lobes. In this study, we sought to assess the role of radiotherapy (RT) and identify prognostic factors in gliomatosis cerebri. METHODS AND MATERIALS: Thirty patients who received RT at a single institution and had radiographic follow-up were retrospectively reviewed with respect to outcome, radiation parameters, extent of surgery, and chemotherapy. All cases were analyzed histologically and documented. All pathology slides and radiology images were reviewed. RESULTS: The median age at diagnosis was 38.6 years (range 16-68). The median follow-up was 12.8 months (range 3-110). The mean radiation dose was 54.9 Gy, given in a mean of 28 fractions. Radiographic improvement or disease stabilization was achieved in 87% of patients. Clinical improvement was observed in 70%. The median time to progression was 10 months, and it was significantly longer for patients <40 years old (p = 0.0007) and for patients having a tumor histologic subtype other than glioblastoma (p = 0.01). The median overall survival was 18 months and was also longer for patients <40 years (p = 0.0001) and for patients having nonglioblastoma histologic features (p = 0.007). Extensive surgery, administration of chemotherapy, or increased RT volume improved neither overall survival nor the time to disease progression. CONCLUSION: RT is effective against gliomatosis cerebri. Patients who are young and have a nonglioblastoma tumor histologic subtype perform more favorably. In this analysis, no role for chemotherapy, extensive surgery, or whole-brain RT was found.

Adolescent↗
PubMed2003

Phase I trial of adenovirus-mediated p53 gene therapy for recurrent glioma: biological and clinical results.

PURPOSE: Advances in brain tumor biology indicate that transfer of p53 is an alternative therapy for human gliomas. Consequently, we undertook a phase I clinical trial of p53 gene therapy using an adenovirus vector (Ad-p53, INGN 201). MATERIALS AND METHODS: To obtain molecular information regarding the transfer and distribution of exogenous p53 into gliomas after intratumoral injection and to determine the toxicity of intracerebrally injected Ad-p53, patients underwent a two-stage approach. In stage 1, Ad-p53 was stereotactically injected intratumorally via an implanted catheter. In stage 2, the tumor-catheter was resected en bloc, and the postresection cavity was treated with Ad-p53. This protocol provided intact Ad-p53-treated biologic specimens that could be analyzed for molecular end points, and because the resection cavity itself was injected with Ad-p53, patients could be observed for clinical toxicity. RESULTS: Of fifteen patients enrolled, twelve underwent both treatment stages. In all patients, exogenous p53 protein was detected within the nuclei of astrocytic tumor cells. Exogenous p53 transactivated p21CIP/WAF and induced apoptosis. However, transfected cells resided on average within 5 mm of the injection site. Clinical toxicity was minimal and a maximum-tolerated dose was not reached. Although anti-adenovirus type 5 (Ad5) titers increased in most patients, there was no evidence of systemic viral dissemination. CONCLUSION: Intratumoral injection of Ad-p53 allowed for exogenous transfer of the p53 gene and expression of functional p53 protein. However, at the dose and schedule evaluated, transduced cells were only found within a short distance of the injection site. Although toxicity was minimal, widespread distribution of this agent remains a significant goal.

Adenoviridae↗
PubMed2003

Preclinical characterization of the antiglioma activity of a tropism-enhanced adenovirus targeted to the retinoblastoma pathway.

BACKGROUND: Oncolytic adenoviruses are promising therapies for the treatment of gliomas. However, untargeted viral replication and the paucity of coxsackie-adenovirus receptors (CARs) on tumor cells are major stumbling blocks for adenovirus-based treatment. We studied the antiglioma activity of the tumor-selective Delta-24 adenovirus, which encompasses an early 1 A adenoviral (E1A) deletion in the retinoblastoma (Rb) protein-binding region, and of the Delta-24-RGD adenovirus. Delta-24-RGD has an RGD-4C peptide motif inserted into the adenoviral fiber, which allows the adenovirus to anchor directly to integrins. METHODS: CAR and integrin expression were examined by flow cytometry in six glioma cell lines and in normal human astrocytes (NHAs). Adenoviral vectors containing green fluorescent protein (GFP) (AdGFP and AdGFP-RGD) were used to infect glioma cell lines with high or low CAR expression. Viability of glioma cells infected with different adenoviruses was assessed by trypan blue staining. Adenovirus replication was quantified with the infection-dose replication assay. Athymic mice carrying glioma xenografts received intratumoral injections of Delta-24-RGD or Delta-24 and were followed for survival, which was analyzed by the Kaplan-Meier method and the log-rank test. All statistical tests were two-sided. RESULTS: Half the glioma cell lines expressed low levels of CAR (defined as <50% of cells expressing detectable CAR); all lines expressed integrins in more than 50% of cells. Infection of U-87 MG cells (a low-CAR-expressing line) with AdGFP-RGD resulted in approximately six times more GFP-positive cells than infection with AdGFP. Delta-24-RGD was more cytopathic to both low- and high-CAR-expressing glioma lines than Delta-24, and it replicated more efficiently in both cell lines. In the xenografted mice, intratumoral injection of Delta-24-RGD was associated with longer survival than intratumoral injection of Delta-24 (P<.001, log-rank test). Furthermore, 60% of Delta-24-RGD-treated mice but only 15% of Delta-24-treated mice survived more than 4 months (difference = 45%, 95% CI = 21% to 68%). CONCLUSIONS: The antitumor activity of Delta-24-RGD suggests that it has the potential to be an effective agent in the treatment of gliomas.

Adenoviridae↗
PubMed2003

Melanoma metastatic to central neurocytoma: a novel case of tumor-to-tumor metastasis.

We report a case of a 43-year-old man with known metastatic melanoma and two intracranial tumors, one of which was resected and confirmed to be melanoma. At autopsy, the second lesion was found to be a central neurocytoma harboring metastatic melanoma. To our knowledge, this represents the first reported case of tumor-to-tumor metastasis to a central neurocytoma. The most common pattern of tumor-to-tumor metastasis for intracranial neoplasms, in which an aggressive high-grade malignancy serves as the source tumor and a more indolent neoplasm serves as the recipient tumor, is affirmed by the present novel example.

Adult↗
PubMed2003

The prognostic value of neurologic function in astrocytic spinal cord glioma.

To assess the prognostic value of neurologic function (NF) in patients with astrocytic spinal cord glioma, we conducted a retrospective study of 25 patients who were treated at our institution between January 1970 and December 1999. The median age was 40 years, and the median follow-up was 54 months. Nineteen patients had a biopsy, 5 had a subtotal resection, and 1 had a gross total resection. Twenty-two patients received postoperative radiotherapy to a median dose of 45 Gy. NF ratings of 1 and 2 were considered favorable, and 3 and 4 were considered unfavorable, based on a scale of 1 to 4. Dual neuropathologic review confirmed the tumor to be low, intermediate, or high grade, based on the WHO grades I-II, III, or IV, respectively. Actuarial rates of local control (LC), progression-free survival (PFS), and overall survival (OS) were analyzed. Our study results revealed that an improved 5-year OS rate was associated with favorable NF at diagnosis (73% vs. 22% for patients with unfavorable NF; P = 0.04) and favorable NF before radiation therapy (89% vs. 28% for patients with unfavorable NF; P = 0.049). There was a significant difference in OS based on tumor grade ( P < 0.001) and age (risk ratio, 1.04; P = 0.027). PFS and LC were significantly better for young patients and those with lower tumor grade ( P < 0.05). A multivariate analysis of age, NF at diagnosis, and postoperative NF for all patients showed postoperative NF and age to be independent prognostic factors for OS. We conclude that favorable NF may be associated with improved outcome in patients with astrocytic spinal cord glioma.

Adolescent↗
PubMed2002

Ink4a-Arf loss cooperates with KRas activation in astrocytes and neural progenitors to generate glioblastomas of various morphologies depending on activated Akt.

Deletion of the INK4a-ARF locus is found in the majority of human malignant gliomas. However, the role of INK4a-ARF loss in gliomagenesis is unclear. Animal modeling has shown that mice with targeted deletions in the Ink4a-Arf gene do not develop spontaneous gliomas. We have previously reported that combined KRas and Akt signaling could induce glioblastoma (GBM) formation from neural progenitor cells but had no effect in differentiated astrocytes. In this investigation, we have studied the effects of Ink4a-Arf loss on the formation of GBM induced by KRas and Akt gene transfer into neural progenitor cells and astrocytes. We show here that Ink4a-Arf deficiency allows for GBM formation from astrocytes and that it enhances tumor incidence in neural progenitor cells. Furthermore, KRas alone can cooperate with deletion of the Ink4a-Arf locus in tumor formation from both neural progenitor cells and astrocytes. The resulting tumors were nestin positive and resembled a spectrum of glioma morphologies ranging in astrocytic character depending on cell-of-origin and presence of activated Akt. Our data strongly supports the view that one role of loss of Ink4a-Arf in gliomagenesis could be to sensitize astrocytes to transformation through dedifferentiation in response to the appropriate oncogenic stimuli.

Animals↗
PubMed2002

Obtaining reliable information from minute amounts of RNA using cDNA microarrays.

BACKGROUND: High density cDNA microarray technology provides a powerful tool to survey the activity of thousands of genes in normal and diseased cells, which helps us both to understand the molecular basis of the disease and to identify potential targets for therapeutic intervention. The promise of this technology has been hampered by the large amount of biological material required for the experiments (more than 50 microg of total RNA per array). We have modified an amplification procedure that requires only 1 microg of total RNA. Analyses of the results showed that most genes that were detected as expressed or differentially expressed using the regular protocol were also detected using the amplification protocol. In addition, many genes that were undetected or weakly detected using the regular protocol were clearly detected using the amplification protocol. We have carried out a series of confirmation studies by northern blotting, western blotting, and immunohistochemistry assays. RESULTS: Our results showed that most of the new information revealed by the amplification protocol represents real gene activity in the cells. CONCLUSION: We have confirmed a powerful and consistent cDNA microarray procedure that can be used to study minute amounts of biological tissue.

Journal Article↗
PubMed2002

Constitutive activation of Stat3alpha in brain tumors: localization to tumor endothelial cells and activation by the endothelial tyrosine kinase receptor (VEGFR-2).

Members of the normally latent family of transcription factors signal/inducers and activators of transcription (Stat) are activated in a number of human tumors and tumor-derived cell lines. In the case of Stat3, it is believed that this activation leads to the induction of survival signals as well as increased proliferation. In this study, we demonstrate that Stat3 is constitutively activated in glioma and medulloblastoma tumors and that the activated protein localizes predominantly to the tumor endothelial cells in the highly vascularized glioma tumors. Our efforts to elucidate potential mechanism(s) for this activated protein have shown that coexpression of Stat3alpha and the vascular endothelial growth factor receptor-2 (VEGFR-2) result in ligand-independent activation of Stat3alpha tyrosine phosphorylation and subsequent transcriptional activation in non-endothelial cells. We also show that activated Stat3alpha can increase transcription from the vascular endothelial growth factor (VEGF) gene. Taken together, these results suggest that the activated Stat3alpha found in brain tumors may be due to the endothelial tyrosine kinase VEGFR-2 and that Stat3alpha may play a central role in autocrine VEGF activation.

3T3 Cells↗
PubMed2002

Suppression of glioma invasion and growth by adenovirus-mediated delivery of a bicistronic construct containing antisense uPAR and sense p16 gene sequences.

Our previous studies showed that the urokinase-type plasminogen activator receptor (uPAR) and the p16 tumor suppressor gene play a significant role in glioma invasion. We expected that downregulation of uPAR and overexpression of p16 using a bicistronic vector might cause a additive and cooperative effect in the suppression of glioma invasion and growth. The bicistronic construct (Ad-uPAR/p16)-infected glioblastoma cell lines had significantly lower levels of uPAR and higher levels of p16 than controls. Cell cycle analysis showed the bicistronic vector caused G0/G1 arrest of the cell cycle. In vitro glioblastoma cell growth and invasiveness were inhibited in Ad-uPAR/p16-infected cells compared with controls. Ad-uPAR/p16 suppressed the tumor growth of glioblastoma cell lines in an ex vivo intracerebral tumor model and an in vivo subcutaneous tumor model. Our results support the therapeutic potential of simultaneously targeting uPAR and p16 in the treatment of gliomas.

Adenoviridae↗
PubMed2002

Demyelinating pseudotumor.

Demyelinating disease presenting as a solitary contrast-enhancing mass poses a diagnostic challenge for both radiologists and surgical pathologists. We report the cases of two female patients, aged 23 and 37 years, who exhibited the clinical and radiologic features of a space-occupying mass strongly suggestive of neoplasia. In both patients, magnetic resonance imaging showed a ring-enhancing parietal lesion. Intraoperative frozen sections in both patients displayed histologic features strongly suggestive of a glial neoplasm, including marked hypercellularity, a prominent astrocytic component, and easily identifiable mitotic figures. However, permanent sections showed additional and helpful histologic findings that included Creutzfeldt astrocytes and granular mitoses. Subsequent immunostaining showed that the hypercellularity was principally caused by macrophage infiltration (HAM-56 and CD68) and an associated reactive astrocytosis (glial fibrillary acidic protein). Additional confirmatory tests included special stains for myelin (Luxol-fast-blue), which demonstrated focal, sharply marginated loss of myelin, and for axons (silver stain for axons and neurofilament protein immunohistochemistry), which showed relative preservation of axons in areas of myelin loss. Together, the special stains confirmed the demyelinating nature of the lesions. The keys to avoiding misdiagnosing a demyelinating pseudotumor as a diffuse glioma include a general awareness of this potential pitfall, including the radiologic appearance of demyelinating pseudotumors as contrast-enhancing solitary masses that mimic tumor; knowledge of the characteristic histologic features, including Creutzfeldt astrocytes and granular mitoses; and a high index of suspicion for macrophage infiltration combined with a willingness to use appropriate confirmatory immunohistochemical studies in suspicious or uncertain cases. This approach will minimize the chance of misdiagnosis and subsequent use of inappropriate and deleterious therapies.

Adult↗
PubMed2002

High-throughput molecular profiling of high-grade astrocytomas: the utility of fluorescence in situ hybridization on tissue microarrays (TMA-FISH).

Due to recent biological and technical advances, the list of potentially useful candidate genes is rapidly expanding in the study of brain tumors. However, traditional methods of screening individual genes in individual samples are slow and tedious, often with consumption of precious resources after only a few experiments. This study evaluates the feasibility of high-throughput molecular analysis using fluorescence in situ hybridization (FISH) on glioma tissue microarrays (TMA). A single microarray paraffin block was constructed using 65 WHO grade III and IV astrocytomas, sampled in duplicate with 0.6-mm-diameter punch cores. FISH was used to detect common alterations, such as EGFR amplification, chromosome 7, 9, and 10 aneusomies and deletions of 1p, 19q, PTEN, DMBT1, and p16. Of 585 hybridization sets, 508 (87%) yielded interpretable data, with hybridization failure in 33 (5.5%) and dislodged tissue in 44 sets (7.5%), respectively. Glioblastomas harbored significantly more alterations than anaplastic astrocytomas, with the overall frequencies of alterations similar to those reported using other techniques. The overall concordance rate between paired tumor core samples was 93%. We conclude that TMA-FISH is an efficient and reliable method for detecting molecular alterations in high-grade astrocytomas.

Agglutinins↗
PubMed2002

Paraneoplastic chorea: case study with autopsy confirmation.

A 67-year-old man presented with a 7-month history of insidiously progressive chorea, ataxia, and vertigo. Neurologic examination revealed deficits referable to the basal nuclei, cerebellar vermis, and vestibular nuclei. Small-cell lung cancer was diagnosed by fine-needle biopsy of a parahilar mass. After chemotherapy, the patient's chorea worsened. Anti-Hu antibodies were present in serum and cerebrospinal fluid. Microscopic examination of the brain at autopsy revealed diffuse perivascular lymphocytic infiltrates, microglial activation, and neuronophagia throughout the neuraxis, including the brainstem, cerebellum, lenticular nuclei, striatum, and cerebral cortex. Prominent loss of Purkinje cells was seen in the cerebellar vermis and hemispheres to a lesser degree. Chorea is extremely rare as a paraneoplastic manifestation of cancer. The florid presentation and the positive findings contrasted with an unremarkable MRI of the brain. This case illustrates the preeminence of symptoms and signs over negative MRI findings in paraneoplastic encephalitis.

Brain↗
PubMed2002

Toward better early-phase brain tumor clinical trials: a reappraisal of current methods and proposals for future strategies.

Although no optimal treatment is currently available for malignant brain tumors, as the molecular mechanisms underlying brain tumor development have been delineated, new chemotherapeutic agents that act directly on specific molecular targets have become available. Defining a specific molecular target raises the possibility that the molecular effects of a given agent can be analyzed in patients in a clinical trial. Specifically, whereas standard phase I and II clinical trials classically determine the safety and efficacy of agents by using indirect global end points, these new biological agents afford the opportunity to incorporate molecular end points into phase I and II clinical trials to determine whether the agent under investigation is actually doing what it was intended to do. This work presents avenues for improving current brain tumor clinical trial designs based on the molecular specificity of new agents and the unique features of brain tumors. Specifically, the authors recommend brain-applicable phase I and II clinical trial strategies that take advantage of the targeted nature of new agents to maximize information about their efficacy, toxicity, and molecular effects.

Brain Neoplasms↗
PubMed2002

Necrosis and glioblastoma: a friend or a foe? A review and a hypothesis.

OBJECTIVE: Two main forms of cell death are encountered in biology: apoptosis (i.e., programmed cell death) and necrosis (i.e., accidental cell death). Because necrosis and apoptosis can lead to cell removal, one might intuit that they are both desirable in cancer treatment. However, in the setting of glioblastoma multiforme, a malignant brain tumor for which the presence of necrosis is an important diagnostic feature, clinical studies indicate that as the degree of necrosis advances, the patient's prognosis worsens. Despite the apparent importance of this form of cell death, the mechanism of development of necrosis in glioblastomas remains unelucidated. The purpose of this article is to try to resolve this dilemma by hypothesizing the mechanism of necrosis formation in these tumors. METHODS: On the basis of an extensive review of the literature, we present a hypothesis for the mechanism of necrosis formation in glioblastoma multiforme. RESULTS: One of the many possible pathways leading to necrosis formation may involve increased tumor cell secretion of tumor necrosis factor. Procoagulation and antiapoptotic mechanisms resulting from certain pathways could prevent the completion of tumor necrosis factor-induced apoptosis and could promote necrosis as the final mode of cell death. Such a hypothesis would explain the inverse correlation that exists between tumor necrosis and the survival of patients with glioblastomas, because the hypoxia that results from procoagulation selects for tumor cells that are more aggressive and more resistant to apoptosis-inducing therapies. CONCLUSION: A complete understanding of the series of events surrounding necrosis development in glioblastomas that is evidence-based is likely to provide targets for future therapies. On the basis of the potential mechanisms of development of necrosis described in this article, we postulate that effective therapies may have to be directed against the pathways that result in the formation of necrosis.

Apoptosis↗
PubMed2002

Sacrococcygeal ganglioneuroma.

Ganglioneuromas are benign slow-growing masses that can be treated with complete surgical extirpation without any adjuvant therapy. Such lesions involving the sacrococcygeal region are exceedingly rare. The authors present the case of a 70-year-old woman with a sacrococcygeal ganglioneuroma treated by total en bloc resection. This patient also had a previous coccygeal fracture. To the authors' knowledge, there are no other reports of ganglioneuroma in association with a history of trauma.

Aged↗
PubMed2002

Insulin-like growth factor binding protein 2: gene expression microarrays and the hypothesis-generation paradigm.

A major goal of modern medicine is to identify key genes and their products that are altered in the diseased state and to elucidate the molecular mechanisms underlying disease development, progression, and resistance to therapy. This is a daunting task given the exceptionally high complexity of the human genome. The paradigm for research has historically been hypothesis-driven despite the fact that the hypotheses under scrutiny often rest on tenuous subjective grounds or are derived from and dependent on chance observation. The imminent deciphering of the complete human genome, coupled with recent advances in high-throughput bioanalytical technology, has made possible a new paradigm in which data-based hypothesis-generation is the initial step in the investigative process, followed by hypothesis-testing. Genomics technologies are the primary source of the new hypothesis-generating capabilities that are now empowering biomedical researchers. The synergistic interaction between contemporary genomics technologies and the hypothesis-generation paradigm is well-illustrated by the discovery and subsequent ongoing study of the role of insulin-like growth factor binding protein 2 (IGFBP2) in human glioma biology. Using gene expression microarray technology, the IGFBP2 gene was recently found to be highly and differentially overexpressed in the most advanced grade of human glioma, glioblastoma. Based on this discovery, subsequent functional studies were initiated that suggest that IGFBP2 overexpression may contribute to the invasive nature of glioblastoma, and that IGFBP2 may exert its function via a newly identified novel binding protein. The IGFBP2 story is but one example of the power and potential of the new molecular methodologies that are transforming modern diagnostic and investigative neuropathology.

Brain Neoplasms↗