Hepatocyte growth factor (HGF) and receptor (c-met) in normal and malignant astrocytic cells

BACKGROUND

Hepatocyte growth factor (HGF) is a multifunctional peptide that binds to a specific receptor, c-met. Both HGF and c-met have been identified in normal brain and on glial tumors. The purpose of this study is to further define the biologic importance of HGF and c-met on normal and malignant glial cells grown in vitro.

MATERIALS AND METHODS

Nine human malignant glioma-derived tumor cell cultures and cultures of astrocytes derived from normal brain were examined for c-met and HGF transcripts using Northern blot or RT-PCR analysis. Cellular invasiveness was quantitated by mechanical assay and mitogenesis was determined by cell count.

RESULTS

C-met was expressed in five of seven malignant glioma-derived tumor cell cultures and in both normal astrocyte cultures. HGF transcript was not detected in any of the cell cultures. HGF supplementation enhanced invasiveness in c-met positive cell lines and did not alter cellular mitogenesis in the assayed cultures.

CONCLUSIONS

These findings suggest that HGF is a potent stimulator of invasiveness in c-met positive malignant glioma-derived tumor cells and is not an active cytokine with regards to in vitro glial cell proliferation. HGF may therefore stimulate glioma cellular invasion in vivo through binding to its receptor and by activating tyrosine kinase secondary messengers.

Variability of intracellular concentrations of basic fibroblast growth factor in cultured human gliomas

BACKGROUND

Basic fibroblast growth factor (bFGF) is a small peptide with angiogenic and mitogenic properties that supports the growth and proliteration of human malignant glial tumors in vitro and in vivo in an autocrine fashion. The purpose of this study was to examine the potential relationship between intracellular bFGF concentrations and grade of glial malignancy using a monolayer cell culture system.

MATERIALS AND METHODS

Samples from 13 histopathologically verified astrocytic brain tumors and two non-tumorous astrocyte specimens were grown in tissue culture and examined both early and late after explantation together with a bFGF-producing reference cell line.

RESULTS

Elevated intracellular concentrations of bFGF were noted in the reference line as well as two of five other glioblastoma multiforme-derived cell cultules, three of five anaplastic glioma-derived cell cultures, and two of three astrocytoma-derived cell cultures. The cells derived from non-tumorous astrocyte specimens expressed low concentrations of bFGF.

CONCLUSION

This study demonstrates that overlap exists between the grade ot glial malignancy and intracellular bFGF levels.

Morphologic, immunologic, biochemical, and cytogenetic characteristics of the human glioblastoma-derived cell line, SNB-19

Human glioma-derived cell cultures and lines have proven to be of significant value in the study of the basic properties that contribute to the highly malignant, invasive and angiogenic phenotype of glioblastoma multiforme tumors. It is frequently difficult to establish lines that retain glial tumor properties in long term culture. The SNB-19 cell line has maintained and exhibited properties of transformation, differentiation, autocrine growth response, and tumorigenesis while remaining in culture for over 13 yr and undergoing over 200 passages. This human line has been utilized in a wide range of studies related to the basic properties of human glioblastoma multiforme. In this report, we summarize the immunologic, biochemical, and cytogenetic properties of this versatile cell line and its utility for additional mechanistic investigation into the pathophysiology of the progression of human malignant gliomas.

The effect of lipoproteins on human glioblastoma growth in vitro

Experiments were performed using an established human glioblastoma cell line to determine the effect of lipoproteins on regulating their growth. It was found that synthetic and natural human high density lipoproteins (HDL) were effective in inhibiting tumor cell growth in a nontoxic, dose-dependent manner, and that the LD50 was 10-fold lower than that for normal rat astrocytes grown under identical conditions. In the presence of the antioxidant, glutathione, essentially all of the growth-inhibiting properties of HDL could be reversed suggesting that oxidized lipids from the HDL interacting with the plasma membranes of the glioblastoma cells were responsible for the growth-inhibiting effect observed. The markedly lower concentration of HDL required to inhibit glioblastoma cells in culture compared to normal astrocytes suggested that the mechanism of HDL-induced inhibition may be important for tumor growth in vivo. One possible mechanism under investigation is the possibility of HDL modulation of a membrane-associated, tumor-specific phosphatase.

Anatomy of the splanchnic circulation

The blood supply to the intestines is a complex one, including branches of the three main splanchnic arteries as well as a vast collateral circulation. The variant anatomy and collateral pathways are described, based on anatomic dissections and angiographic studies, to focus attention on anatomically based explanations for clinical entities.

Selective cytoplasmic and membrane changes induced by cisplatinum

Cisplatinum (cis-dichlorodiammineplatinum II (NSC-119875], proven to be of therapeutic value in a variety of solid tumors, is thought to have DNA as its major target. Prior in vitro studies have suggested that it also induced cell membrane and cytoplasmic changes. To better understand glial tumor cell sensitivity to cisplatinum and to design more effective adjuvant therapy, three cisplatinum sensitive human glioma-derived cell lines, SNB-1, SNB-3, SNB-4, were examined by transmission electron microscopy for cisplatinum induced changes. Tumor cells were exposed to 25, 50, and 100 micrograms/ml cisplatinum in medium for varying time periods (4-72 hours). Four changes were consistent: cell rounding and reduced nuclear-cytoplasmic ratio, nuclear chromatin clumping, vesiculation and swelling of the golgi apparatus, and dilatation of the smooth endoplasmic reticulum. These morphologic changes are distinct for cisplatinum and unlike those induced by BCNU (plasma membrane blebbing) and AZQ (mitochondrial swelling and destruction) previously seen in our laboratory. The cellular events described here suggest that cytoplasmic, as well as nuclear, changes (occurring within the same time intervals) may both be relevant to the antitumor effects of cisplatinum.

Basic fibroblast growth factor: a potential autocrine regulator of human glioma cell growth

Basic fibroblast growth factor (bFGF) is a potent mitogen and angiogenic factor. bFGF is expressed by a variety of solid human tumors and has been implicated as an autocrine regulator of tumor growth. Different solid tumor lines including glioma, colon carcinoma and melanoma were examined for intracellular immunoreactive bFGF, high- and low-affinity bFGF receptors and mitogenic response to bFGF when grown in chemically defined medium. All tumor lines contained significant levels of bFGF. In addition, all tumor lines contained subsets of five forms of immunoreactive bFGF, as well as 0.68-20 x 10(6) low affinity bFGF binding sites (Kd = 15-300 nM). Most, but not all lines exhibited high affinity bFGF receptors (Kd = 25-40 pM). Glioma cell lines were distinguished by expressing the highest levels of bFGF protein as well as the most high-affinity receptors for bFGF. Furthermore, glioma cell lines were the only tumor type mitogenically responsive to bFGF. These results indicate that glioma cells express high levels of this potent mitogen and angiogenic factor relative to human colon carcinoma and melanoma cells. The expression of bFGF and bFGF receptors by glioma cells may be related to abnormal growth and neoplastic progression in these tumors.

Effect of phorbol esters on the susceptibility of a glioma cell line to lymphokine-activated killer cell activity

The mechanisms by which lymphokine-activated killer (LAK) cells exert their cytotoxic effects are not well understood. This study demonstrates that phorbol ester pretreatment of a LAK cell-sensitive glioma cell line (SNB-19) induced a significant decrease in the susceptibility of cells to LAK cell-mediated lysis. This effect was produced by low concentrations of the tumor-promoting phorbol ester, phorbol-12,13-myristate acetate (PMA), and was reversible. Protein kinase C (PKC) inhibitors failed to block this phenomenon. No apparent alteration in the ability of LAK cells to bind to their targets was observed. Thus, PMA may have exerted its effects by a mechanism that does not require PKC, or these glioma cells may possess an isozyme of PKC which is insensitive to the inhibitors used in these studies.

Basic fibroblast growth factor-like activity and receptors are expressed in a human glioma cell line

Basic fibroblast growth factor (bFGF), a potent mitogen and angiogenic peptide, has been examined as an autocrine regulator of glioma cell growth. The addition of purified bovine pituitary bFGF to an established human glioma cell line, SNB-19, doubled the density of these cells in chemically defined medium. Half-maximal stimulation occurred at 8.2 ng/ml (480 pM). Also, human recombinant bFGF (hr-bFGF) significantly enhanced the growth of SNB-19 cells in soft agar. SNB-19 cells expressed both high and low affinity binding sites for hr-bFGF. These cells expressed approximately 13,000 high affinity sites/cell (Kd = 16.6 +/- 1.7 pM) and 9.5 x 10(6) low affinity sites/cell (Kd = 61.2 +/- 4.1 nM). The results of cross-linking experiments with iodinated hr-bFGF demonstrated the presence of two bands with molecular masses of 145 and 130 kDa. High affinity receptors were also demonstrated in SNB-19 tumors grown in nude mice. SNB-19 cell extracts contained mitogenic activity that eluted from heparin-agarose with high salt (1.2-2 M NaCl) and exhibited many properties normally associated with authentic bFGF. This material cross-reacted with a monoclonal antibody to hr-bFGF, comigrated with hr-bFGF by Western blot analysis, competed with 125I-hr-bFGF in a radioreceptor assay, and stimulated SNB-19 cell growth. These results indicate that a human glioma cell line both expresses and utilizes a bFGF-like growth factor. Such a factor may be an important autocrine regulator of glioma cell growth and may also facilitate its neoplastic progression.

Plasminogen activator and inhibitor activity in human glioma cells and modulation by sodium butyrate

The activity of the serine protease plasminogen activator (PA), which correlates with tumorigenicity and metastatic capacity, was examined using the 125I-labeled fibrin plate assay in cell extracts from four human glioma lines as a function of growth in vitro. Cell-associated inhibitory activity to plasmin and urokinase-type PA was also measured concurrently. The relative PA activities differed markedly among the lines, whereas inhibitory activities did not. Two lines, SNB-19 and SNB-75, exhibited maximal PA activities (1-6 m Plough units/micrograms protein) as cultures approached confluence, whereas two other lines, SNB-56 and SNB-78, expressed low PA activity at all times (less than 0.2 m Plough units/micrograms protein). The PA of SNB-19 cell extracts was predominantly urokinase-type PA. In addition to having the highest PA levels, SNB-19 and SNB-75 were the most clonogenic in soft agar and tumorigenic in nude mice. In contrast, SNB-56 and SNB-78 were poorly clonogenic in soft agar and were not tumorigenic in nude mice. Measured directly, inhibitory activities to plasmin, urokinase-type PA, and tissue-type PA were detected in SNB-19 (high PA) and SNB-56 (low PA) cell extracts. However, there were no qualitative or quantitative differences in inhibitor effects between SNB-19 and SNB-56 suggesting that the differences in PA activity between these lines resulted from changes in PA activity and were not due to differential plasminogen activator inhibitor effects. The ability of the differentiating agent sodium butyrate (NaB) to modulate total PA activity was also examined. Peak SNB-19 cell PA activity was decreased in a concentration (Ki, 0.75 mM) and time-dependent manner by the addition of nontoxic amounts of NaB. The dose-dependent decrease in PA activity induced by NaB was most likely due to an effect on PA itself, since the action of inhibitor on urokinase was unchanged in response to NaB. These results suggest that net cellular PA activity in glioma cells is a balance between relative PA activity and inhibitor(s) effects and that this balance can be modulated by sodium butyrate.

Chemotherapy for malignant gliomas

There continues to be an extensive effort to develop chemotherapeutic approaches to the treatment of malignant gliomas of the brain. In the past 5 years there have been literally hundreds of trials of new agents, combinations of old and new agents, and even new routes and approaches to the delivery of chemotherapy. In this review, the literature has been studied and the individual reports analyzed to evaluate the impact of the new findings on clinical management of the patient with malignant glioma of the brain. The major areas of progress include the addition of new drugs with varying modes of action, the use of combinations of drugs in a synergistic fashion, and the development of new routes of drug delivery. None of the advances has brought about the revolution in clinical care that is so eagerly sought, but clearly the amount of new knowledge gained by these studies helps in understanding how to use chemotherapy more effectively. Furthermore, the remarkable degree of interest and involvement in the use of chemotherapy promises that an even greater number of patients with malignant gliomas will be considered for vigorous and enthusiastic clinical management programs even if chemotherapy itself is not the key modality in the treatment of a specific patient.

DNA cross-linking responses of human malignant glioma cell strains to chloroethylnitrosoureas, cisplatin, and diaziquone

Cell strains derived by culture of malignant glioma (astrocytoma grade III-IV) surgical specimens were tested for the production of DNA interstrand cross-links (ISC) and DNA-protein cross-links following treatment in vitro with 1-(2-chloroethyl)-1-nitrosourea, 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU, carmustine), 1-(2-chloroethyl)-3-(2,6-dioxo-1-piperidyl)-1-nitrosourea (PCNU), cis-dichlorodiammineplatinum(II) (cisplatin), and 3,6-diaziridinyl-2,5-bis(carboethoxyamino)-1,4-benzoquinone (diaziquone). ISC and DNA-protein crosslinks were measured by means of the DNA alkaline elution technique. Large differences among the cell strains were observed in DNA cross-linking responses to individual agents. The DNA responses to the chloroethylnitrosoureas, cisplatin, and diaziquone were largely independent of each other, except for a weak correlation between ISC responses to chloroethylnitrosoureas were distributed bimodally, in accord with a phenotypic distinction between Mer+ and Mer- cells. ISC responses to cisplatin and diaziquone showed significant variation among cell strains, but the distributions were not bimodal. The results demonstrate the existence of diverse DNA cross-linking response patterns among cell strains from different tumors of a given histological type.

Products of cells cultured from gliomas. VI. Immunofluorescent, morphometric, and ultrastructural characterization of two different cell types growing from explants of human gliomas

Explants derived from human gliomas have been characterized with respect to their cellular outgrowth pattern after 1-22 weeks in culture. A mat of cells which were fibronectin (FN)-positive and glial fibrillary acidic protein (GFAP)-negative (hereafter designated FN+ cells) with a polygonal, flat morphology covered the growth substrate in a swirling pattern for a mean diameter of 9.2 mm around FN+ explants. FN+ cells showed ruffled plasmalemma, dilated rough endoplasmic reticulin (RDR), and extracellular filamentous strands. Rare desmosomes were compatible with at most minor leptomeningeal components or differentiation. FN+ cells predominated in six of seven cultures at passage 2, and their features were the same from various high-grade gliomas and gliosarcoma. Around other explants, elongated or stellate cells which were GFAP+ and FN- grew in a netlike pattern with little cell-to-cell contact. These GFAP+ cells surrounded explants at a mean diameter of 2 mm, substantially less than FN+ cells (P less than 0.005), and they grew more slowly than FN+ cells around explants. GFAP+ cells had an area/perimeter ratio which was less than that of FN+ cells. GFAP+ cells contained abundant intracellular filaments, rare desmosomes, and narrow RER cisternae. In mixed explants, GFAP+ cells often grew on top of FN+ cells. Individual cells which stained for both GFAP and FN were evident only from one glioma (8% doubly positive). Cells negative for both proteins resembled FN+ cells morphologically. Frozen sections of original glioma tissue showed FN+ vessel walls and GFAP+ parenchyma. Results are evidence for very early overgrowth of a preexistent FN+ cell type distinct from the GFAP+ parenchymal cell. The features of this distinct cell type are mesenchymal and resemble the proliferating vascular elements of gliomas in situ. The tendency for GFAP+ cells to grow on top of these FN+ cells suggests a feeder layer interaction. More knowledge of the origins and interactions of these two cell types may increase our understanding of the mechanism of antigenic changes in gliomas and may provide clues to improved therapeutic approaches.

Immunocytochemical localization of factor VIII-related antigen in tumors of the human central nervous system

Using both immunohisto- and immunocytochemical techniques with periodate-lysine-paraformaldehyde (PLP) fixation, we have studied the distribution of Factor VIII-related antigen (FVIIIR:Ag) in 12 cases of tumors of the human central nervous system (CNS) and one sample of non-tumor brain tissue. FVIIIR:Ag was found both extracellularly and intracellularly. It was localized in the vascular lumen, between endothelial cells, and in the endothelial cell basement membrane. In the endothelial cell cytoplasm, FVIIIR:Ag was found in the endoplasmic reticulum, perinuclear space, and in intracytoplasmic vacuoles and vesicles. Characteristic of malignant tumors (six out of seven) was a strongly-positive dilated endoplasmic reticulum. This may reflect increased FVIIIR:Ag synthesis in the endothelial cells of malignant tumors. Only one of five benign tumors showed such staining. Six of 12 tumors and the non-tumor brain showed perinuclear FVIIIR:Ag. Both ad- and abluminal vesicles in the tumor endothelial cells contained FVIIIR:Ag suggesting that endocytosis, transcellular transport, and/or endocytosis, as well as FVIIIR:Ag synthesis occurs. The non-tumor brain showed normal capillary structure and very little FVIIIR:Ag immunoreactivity. The relationship of these FVIIIR:Ag abnormalities to the hypercoagulable state seen in some malignant brain tumor patients remains to be clarified.

Lymphokine activated killer (LAK) cell mediated killing of human glioma: effect of pretreating glioma with various membrane modifying agents

The killing of human glioma by lymphokine activated killer (LAK) cells was studied. LAK cells generated by culturing recombinant interleukin-2 (IL-2) with human peripheral blood lymphocytes (PBL) obtained from normal volunteers markedly lysed allogeneic glioma grown in tissue culture. Susceptibility of glioma to lysis by LAK cells was abrogated by pretreating the glioma cells with trypsin or chymotrypsin, but was unaffected by pretreatment with hydrocortisone, neuraminidase, glycosidases or sodium periodate. These results suggest that the cell surface determinant on human glioma cells responsible for its tumor selective lysis by LAK is a protein sensitive to trypsin and chymotrypsin.

Interleukin-2 and lymphokine activated killer (LAK) cells in the treatment of malignant glioma: clinical and experimental studies

The phenomenon of glioma killing by lymphokine activated killer cells (LAK) was studied. We demonstrate that LAK cells generated by culturing the lymphokine interleukin-2 (IL-2) with peripheral blood lymphocytes from brain tumour patients destroys autologous glioma. The rat 9L glioma model was used to show that LAK killing was tumour-selective as glioma but not syngeneic normal brain tissue was destroyed. The susceptibility of both human and 9L rat glioma to LAK cell killing was markedly diminished by pretreating glioma cells with trypsin or chymotrypsin, but was unaffected by pretreatment with neuraminidase, glycosidases, sodium periodate or hydrocortisone. These results suggest that the cell surface determinant on glioma cells responsible for its tumour selective lysis by LAK is a protein sensitive to trypsin and chymotrypsin. The tumour-selective killing of glioma by LAK in vitro prompted the initiation of a Phase I study in which ten patients with malignant glioma have been treated with direct intracerebral injection of IL-2 or LAK without evidence of systemic or brain toxicity.

Lymphokine activated killer (LAK) cell-mediated lysis of murine glioma: trypsin-chymotrypsin-sensitive glioma protein is responsible for tumor-selective recognition by LAK cells

The killing of Fischer rat 9L glioma in vitro by lymphokine-activated killer (LAK) cells was studied. LAK cells generated by culturing Fischer spleen cells with recombinant interleukin 2 markedly lysed glioma cells but did not kill syngeneic normal brain tissue in a chromium release microcytotoxicity assay. Susceptibility of glioma to lysis by LAK cells was markedly diminished by pretreating the glioma cells with trypsin or chymotrypsin but was unaffected by pretreatment with neuraminidase, glycosidases, or sodium periodate. These results suggest that LAK cell killing of glioma is probably tumor-selective and that a crucial cell surface determinant on glioma cells responsible for its tumor-selective lysis by LAK is a protein sensitive to trypsin and chymotrypsin.

Interleukin-2 and autologous lymphokine-activated killer cells in the treatment of malignant glioma. Preliminary report

Nine patients with malignant glioma were treated with the lymphokine interleukin-2 (IL-2) or with lymphokine-activated killer (LAK) cells, and one patient received combination therapy with both LAK cells and IL-2. The LAK cells were generated by culturing recombinant IL-2 with peripheral blood lymphocytes obtained from brain-tumor patients. Escalating doses of LAK cells (10(8) to 10(10] or IL-2 (10(4) to 10(6) U) were administered intraoperatively by direct injection into the brain tissue surrounding the cavity left by debulking the tumor. There were no signs of systemic or neural toxicity following treatment. The selective killing of the tumor by LAK cells used for these treatments was demonstrated by a chromium release microcytotoxicity assay which showed in vitro the ability of the LAK cells to lyse glioma cells but not normal cells.

Interleukin-2 or autologous lymphokine-activated killer cell treatment of malignant glioma: phase I trial

In a Phase I study, recombinant interleukin-2 (IL-2) or autochthohous lymphokine-activated killer (LAK) cells were used to treat nine patients with malignant glioma. One patient received the combination of IL-2 and LAK cells. LAK cells were generated by culturing IL-2 with peripheral blood lymphocytes obtained from brain tumor patients. Escalating doses of LAK cells (10(8)-10(10) or recombinant IL-2 (10(4)-10(6) units) were administered by direct injection into the brain tissue surrounding the cavity left following operative tumor removal. There have been no signs of systemic or neurotoxicity following treatment. The tumor selective killing of the LAK cells used for these treatments was demonstrated by their ability to lyse glioma cells but not normal cells in vitro using a chromium release microcytotoxicity assay.

Response variability of human brain tumors to AZQ in tissue culture

In a series of 28 glioma-derived cell cultures and 6 non-gliomatous CNS tumors, AZQ has been found to have varying degrees of growth inhibiting or cytotoxic activity in nearly all lines tested at doses greater than 100 mcg/ml. At dose levels comparable to the clinically achieved levels (1 mcg/ml), AZQ was found to have a cytotoxic effect in 8 of 28 glioma-derived and 2 of 6 non-gliomatous cell lines tested. These findings suggest that AZQ has activity against certain glioma-derived cells in culture at a response ratio similar to that seen in vivo. There, appear to be significant differences in the degree of responsiveness in different patients' tumor cells which can be detected in vitro prior to clinical treatment.

In vitro killing of human glioblastoma by interleukin-2-activated autologous lymphocytes

Culture of peripheral blood lymphocytes (PBL) from brain-tumor patients with recombinant interleukin-2 (IL-2) results in the activation of lymphokine-activated killer cells (LAK) with the capacity to lyse autologous and allogeneic glioblastoma. In this study, PBL obtained from brain-tumor patients were cultured with or without IL-2 for 3 to 7 days and then tested for their ability to lyse target cells in a 4-hour chromium release cytotoxicity assay. The PBL were drawn 1 to 2 weeks following operative tumor debulking. Cells used as targets included fresh brain-tumor cells obtained at the time of craniotomy, fresh brain-tumor cells grown from 1 to 3 weeks in tissue culture, fresh autologous PBL, and allogeneic glioblastoma cells grown in tissue culture. Peripheral blood lymphocytes from brain-tumor patients that were cultured without IL-2 did not significantly lyse autologous or allogeneic glioblastoma. However, when these PBL were cultured with IL-2, LAK were generated which produced marked lysis of autologous as well as allogeneic tissue-culture glioblastoma in all of eight cases. Significant lysis of autologous fresh tumor by patient LAK was observed in four of five experiments. By contrast, patient LAK did not kill autologous normal PBL. The ability to generate LAK was not influenced by the patient's age, previous therapy, or the administration of steroids.

Glucocorticoid-mediated increases in glycerol phosphate dehydrogenase activity is inhibited by the phorbol ester tumor promoters

An oligodendroglial specific property, glucocorticoid regulation of glycerol-3-phosphate dehydrogenase (GPDH) levels, was inhibited in C6 rat glioma cells when 4 beta-phorbol 12-myristate 13-acetate (PMA) was added to the cultures. PMA inhibited GPDH induction in both logarithmic- and stationary-phase cells. These events are most likely mediated through the phorbol ester receptor since the ability of various phorbol ester analogs to compete with the ligand [3H]4 beta-phorbol 12,13-dibutyrate for binding to the receptor correlates with the ability the particular analog has to inhibit GPDH induction. Additionally, like tumor promotion in vivo, the inhibition of GPDH induction is reversible. The PMA effect is not restricted to the C6 cell line since PMA also inhibits GPDH inducibility in another rat glioma cell line. This PMA-mediated event has been partially characterized. PMA did not affect the overall rate of protein or RNA synthesis. It was ineffective in altering both glucocorticoid accumulation to the nucleus and the rate of GPDH degradation. It appears likely that PMA's inhibitory action occurs at the transcriptional or translational level.

Regulation of hexokinase in cultured gliomas

Positron emission computed tomographic (PECT) scanning studies have demonstrated that high grade gliomas exhibit increased 2-[18F]fluoro-2-deoxyglucose (18FDG) uptake compared to cerebral white matter and low grade gliomas. Hexokinase catalyzes the phosphorylation of glucose, as well as 18FDG and 2-deoxyglucose (2DG), thereby "trapping" these slowly metabolized analogues intracellularly. We hypothesize that a similar hexokinase-mediated uptake of glucose and glucose analogues occurs in vitro. Hexokinase activity was assayed in homogenates of tissue-cultured lines derived from high (IV) and low (II) grade gliomas and in fibroblasts derived from skin. With glucose as substrate, the maximal activity (Vmax) in the Grade IV lines was 200% of the activity found in the Grade II line, fibroblasts, and astrocytes; however, the Michaelis substrate affinity constant (Km) bore no relationship to tumor grade. With 2DG as substrate, the Vmax of all cell lines decreased, but the Grade IV lines still tended to have greater activity than the others. The Km values for 2DG were 5 times higher than those for glucose. Hexokinase is found in two subcellular compartments: an active form reversibly bound to mitochondria and a less active, cytosolic form. Up to 20% of the total hexokinase was found in the cytosol in all lines tested. High energy phosphate compounds (ATP, ADP, CTP, and others) displaced mitochondria-bound hexokinase, which increased the cytosolic form by 2-fold in the glioma lines, but fibroblast hexokinase distribution was unaffected. Our results suggest that: (a) high grade gliomas have increased hexokinase activity, which may explain the grade-related differences in 18FDG uptake observed by PECT scanning, and (b) human glioma hexokinases may be regulated by reversible subcellular compartmentation.

Prediction of survival in glioma patients by means of positron emission tomography

The aim of this study was to determine whether positron emission tomography (PET) with fluorine-18 (18F)-2-deoxyglucose (FDG) can be used as a prognostic test in patients with high-grade cerebral gliomas, regardless of the treatment given. Forty-five patients with astrocytoma Grade III or IV were included in this analysis. The mean survival time of patients with tumors exhibiting high glucose utilization as determined by PET-FDG was 5 months, whereas patients with gliomas showing lower glucose utilization had a mean survival period of 19 months. It is postulated that PET-FDG scans reflect the biological behavior of high-grade astrocytomas and may be used to predict the survival time of patients harboring such neoplasms.

Lysis of intracranial hematomas with urokinase in a rabbit model

Urokinase (UK), a potent thrombolytic agent, was tested in a rabbit model for safety and efficacy in lysing intracranial hematomas. Intracerebral-intraventricular (IC-IV) hematomas were created by stereotaxically injecting 0.2 ml of clotted human blood into the frontal lobe and lateral ventricle of a total of 57 anesthetized adult New Zealand White rabbits (weighing 1.6 to 2.5 kg). Control animals received 0.2 ml of normal saline injected into the clot, and the experimental group received an equal volume of UK solution (50,000 units/ml) immediately after the clot injection. Some animals were sacrificed at 3 hours and others at 24 hours postinjection. At 3 hours, clot lysis had been achieved in nine (90%) of 10 UK-treated animals as compared to one (14%) of seven controls. By 24 hours, clots had been lysed in 10 (83%) of 12 UK-treated animals and in two (33%) of six controls. Overall, clot lysis was demonstrated in 19 (86%) of the 22 UK-treated animals and in only three (23%) of the 13 controls (p less than 0.001). There was no significant difference in results between these animals and a further set of 22 rabbits that were treated with UK or saline 24 hours after clot injection. There was no histological evidence of damage or inflammation noted on careful light microscopic examination of three to five sections from each brain, although findings consistent with encephalitozoonosis, an incidental protozoan infestation, were encountered in four animals. These studies suggest that UK may be safely and effectively employed for the lysis of intracranial hematomas in this animal model, and that a delay in therapy of up to 24 hours does not significantly compromise its efficacy.

Arterial drug infusion with extracorporeal removal. II. Internal carotid carmustine in the rhesus monkey

During cancer chemotherapy by intra-arterial drug administration, systemic toxicity often limits the tolerable dose. We evaluated the pharmacokinetic advantage obtained by infusing carmustine (BCNU) into the internal carotid artery during BCNU removal from the blood from the perfused region by hemoperfusion. A hemoperfusion column (XR-010, Extracorporeal Medical Specialties) was shown to remove BCNU quantitatively from sheep blood flowing at 300 ml/minute when the drug was infused at 13 mg/minute for 30 minutes. Under general anesthesia, adult rhesus monkeys underwent catheterization of the internal carotid artery and placement of a catheter in the ipsilateral jugular vein at its junction with the sigmoid sinus. BCNU (10 mg/kg) was infused over 20 minutes while blood was pumped from the jugular vein through a small column and back into the inferior vena cava. The procedure reduced systemic exposure by 46%-84% compared with iv infusion of the same dose. Brain-to-systemic exposure ratios ranged from 18:1 to 87:1, depending on the pump flow rate and method of calculation. Hematopoietic toxicity was prevented. It is suggested that tumor exposure to BCNU comparable to that associated with very high tumor cell kill in vitro may be feasible with little or no systemic toxicity.

[Tubular bodies (Weibel-Palade) in the endothelial cell of glioblastoma]

Authors have studied the ultrastructure of endothelial cells in the microvessels of malignant and benign gliomas and in particular, the numbers of tubular bodies (Weibel-Palade) in endothelial cells of glioma microvessels in related with blood vessel proliferation. Glioblastoma 6, astrocytoma grade II 1, oligodendroglioma 1 and 2 samples of non-tumor brain tissue were analyzed quantitatively using light and electron microscope with Karnovski fixative. All tissues were obtained from the center, the intermediate and the margin in each tumor tissue and just outside of the tumor at operation. 389 microvessels were examined in the total gliomas electronmicroscopically. Tubular body was first described by Weibel and Palade in the vascular endothelial cells of various organs in both man and animals. This is now considered to be an organelle specific to the endothelial cell, but its function is still unknown. Tubular body observed in the endothelial cells of the gliomas vessels consisted of a membrane-limited round, oval or elongated shaped intra cytoplasmic body (about 0.1-0.2 micron) which contained tubules of 150-200 A outer diameter. Tubular bodies were classified in the two types. One of them (mature type) was relatively electron dense to be more compact, the other (immature type) had relatively pale matrix. In the immature type they are located in close proximity to the Golgi complex or endoplasmic reticulum.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma fibronectin in patients with brain tumors

Fibronectin, a large molecular weight glycoprotein normally found on the surface of many cells, was measured in the plasma of 15 normal volunteers and 75 patients with various kinds of brain tumors or other kinds of neurological disorders. The mean plasma fibronectin in the control group was 253 micrograms/ml. Statistically significant elevations in fibronectin levels were found in patients with progressive high grade astrocytomas (mean = 413 micrograms/ml). The majority of patients with high grade astrocytomas in remission had normal levels of fibronectin (mean = 273 micrograms/ml). Elevations were noted in patients with low grade astrocytomas, meningiomas, and benign nonneoplastic neurological disorders. Plasma fibronectin may be useful diagnostically and therapeutically in identifying and managing some patients with high grade gliomas. However, of greater importance is the observation that fibronectin elevation is the result of a tumor-host interaction.

Active clearance of corticotropin-releasing factor from the cerebrospinal fluid

Intracerebroventricular injection of corticotropin-releasing factor (CRF) in animals activates behavioral, motor, metabolic and sympathetic responses similar to those seen with stress. To explore the pharmacokinetics of this peptide in the primate ventricular CSF, we determined the clearance of ovine 125I-CRF from the CSF and compared it to that of 111In-DTPA, a substance cleared by bulk flow. 125I-CRF was cleared from the ventricular fluid sixfold more rapidly than bulk flow. This suggests that the CSF may be a pathway for physiological distribution of this releasing factor to active sites within the central nervous system, and that a mechanism exists for active removal of CRF from the ventricular CSF.

Corticotropin releasing factor administered into the ventricular CSF stimulates the pituitary-adrenal axis

Ovine corticotropin releasing factor (CRF) given intracerebroventricularly to rhesus monkeys at doses of 0.1-1 microgram/kg activates the pituitary-adrenal axis. The increases of plasma cortisol concentrations after intraventricular injection of CRF were similar to those observed after intravenous administration of this releasing factor and occurred without elevation of plasma concentrations of CRF, measured by radioimmunoassay. Thus, the cerebrospinal fluid (CSF) can serve as a conduit for delivery of CRF to the pituitary gland.

Brain tumors and plasmin inhibitors

Four different intracranial neoplasms inhibited purified plasmin in an in vitro assay. The greatest inhibition (80%) was observed with extracts of a parasagittal meningioma that had invaded and completely occluded the sinus. Significant inhibition (greater than 40%) was also observed with extracts prepared from a glioma surgically removed from a patient who had suffered three thromboembolic episodes during the preceding several months. Lesser (less than 30%) inhibition was obtained with extracts from two other patients who had no evidence of thromboembolic complications. This report constitutes the first demonstration of plasmin inhibition activity in association with brain tumors. Further studies will be required to test the hypothesis that certain intracranial tumors may escape host antitumor fibrinolytic activity by producing plasmin inhibitors and that plasmin inhibitors may play a role in the thromboembolic complications frequently seen in patients with intracranial neoplasms.

In vitro studies on the cell-mediated immune response to human brain tumors. II. Leukocyte-induced coats of glycosaminoglycan increase the resistance of glioma cells to cellular immune attack

We have examined the ability of cultured human glioma cells to elicit allogeneic cytolytic lymphocyte responses in vitro in order to delineate properties of glioma cells that may contribute to their ability to escape cellular immune attack. When glioma cells were cultured together with allogeneic peripheral blood mononuclear cells (PBMC) in mixed lymphocyte-tumor cultures (MLTC), it was observed that cells from eight of 12 glioma lines were surrounded by clear pericellular "halos," which appeared to impede contact between PBMC and the glioma cells. Enzymatic, histochemical, and immunochemical studies indicated that these halos represented glycosaminoglycan (GAG) coats that contained hyaluronic acid (HA) as a major constituent. Electron microscopic studies demonstrated the presence of many thin microvillous processes spanning the width of the halos. The presence of GAG coats around glioma cells in MLTC reduced the generation of cytolytic T lymphocytes specific for antigens on the glioma cells. Likewise, these cell coats decreased the lysis of glioma cells by cytolytic lymphocytes, once generated. The production of thick coats of GAG by glioma cells was induced by interaction of glioma cells with a nondialyzable factor produced by PBMC in culture. This factor did not cause glioma cells to release increased amounts of HA into the medium, but rather increased the production of HA that remained associated with the glioma cell surface. The formation of thick, protective GAG coats by glioma cells as a result of their interaction with the PBMC-derived factor constitutes a nonspecific suppressor mechanism that may contribute to the ability of this class of human solid tumors to evade cellular immune attack.

Proteins in normal, irradiated, and postmortem human brain quantitatively compared by using two-dimensional gel electrophoresis

Using a combination of two-dimensional gel electrophoresis (2DE), silver staining, and computerized densitometry, we studied protein patterns in human cerebral cortex: normal fresh-frozen, fresh-frozen but previously irradiated, and post-mortem. The relative molecular mass of the resolved proteins ranged from 14 400 to 100 000, the isoelectric points from 4.75 to 7.0. The pattern of proteins (six of them identified) was essentially the same for all three groups. However, computerized densitometry demonstrated significant alterations in the density of several spots in the irradiated and postmortem groups as compared with the normal controls. Irradiated cortex showed statistically significant changes in only six spots (three increased and three decreased in density); postmortem material showed 20 altered spots (16 diminished and four increased). Evidently normal human cerebral cortex has a consistent protein pattern on 2DE, which is quantitatively (but not qualitatively) altered in irradiated and postmortem material. These findings provide a point of reference against which proteins from abnormal brain material can be compared, both qualitatively and quantitatively.

Proteins in normal, irradiated, and postmortem human brain quantitatively compared by using two-dimensional gel electrophoresis

Using a combination of two-dimensional gel electrophoresis (2DE), silver staining, and computerized densitometry, we studied protein patterns in human cerebral cortex: normal fresh-frozen, fresh-frozen but previously irradiated, and post-mortem. The relative molecular mass of the resolved proteins ranged from 14 400 to 100 000, the isoelectric points from 4.75 to 7.0. The pattern of proteins (six of them identified) was essentially the same for all three groups. However, computerized densitometry demonstrated significant alterations in the density of several spots in the irradiated and postmortem groups as compared with the normal controls. Irradiated cortex showed statistically significant changes in only six spots (three increased and three decreased in density); postmortem material showed 20 altered spots (16 diminished and four increased). Evidently normal human cerebral cortex has a consistent protein pattern on 2DE, which is quantitatively (but not qualitatively) altered in irradiated and postmortem material. These findings provide a point of reference against which proteins from abnormal brain material can be compared, both qualitatively and quantitatively.

In vitro studies on the cell-mediated immune response to human brain tumors. II. Leukocyte-induced coats of glycosaminoglycan increase the resistance of glioma cells to cellular immune attack

We have examined the ability of cultured human glioma cells to elicit allogeneic cytolytic lymphocyte responses in vitro in order to delineate properties of glioma cells that may contribute to their ability to escape cellular immune attack. When glioma cells were cultured together with allogeneic peripheral blood mononuclear cells (PBMC) in mixed lymphocyte-tumor cultures (MLTC), it was observed that cells from eight of 12 glioma lines were surrounded by clear pericellular "halos," which appeared to impede contact between PBMC and the glioma cells. Enzymatic, histochemical, and immunochemical studies indicated that these halos represented glycosaminoglycan (GAG) coats that contained hyaluronic acid (HA) as a major constituent. Electron microscopic studies demonstrated the presence of many thin microvillous processes spanning the width of the halos. The presence of GAG coats around glioma cells in MLTC reduced the generation of cytolytic T lymphocytes specific for antigens on the glioma cells. Likewise, these cell coats decreased the lysis of glioma cells by cytolytic lymphocytes, once generated. The production of thick coats of GAG by glioma cells was induced by interaction of glioma cells with a nondialyzable factor produced by PBMC in culture. This factor did not cause glioma cells to release increased amounts of HA into the medium, but rather increased the production of HA that remained associated with the glioma cell surface. The formation of thick, protective GAG coats by glioma cells as a result of their interaction with the PBMC-derived factor constitutes a nonspecific suppressor mechanism that may contribute to the ability of this class of human solid tumors to evade cellular immune attack.

A human ganglioglioma containing paired helical filaments

Neurofibrillary tangles composed of paired helical filaments were found in a human ganglioglioma. This is the first reported occurrence of neurofibrillary tangles in a neoplasm. These tangles were visible light microscopically with hematoxylin-eosin and Bodian's stains. They were confirmed as neurofibrillary tangles with Congo red staining under polarized light and with thioflavine S fluorescence. Untrastructurally, the tangles were composed of 10-nm filaments twisted in a helix with 80 nm between constructions. Thus, neoplastic proliferation does not preclude production of paired helical filaments. Cells grew from explants of this tumor, but no paired helical filaments were found in the cells examined. Two other gangliogliomas and normal brain tissue studies by the same procedures did not show paired helical filaments. Gangliogliomas that contain neurofibrillary tangles provide an alternative source of abnormal filaments for analysis.

[Immunocytochemical localization of factor VIII-related antigen in blood vessels of the human central nervous system]

Using both immunohistochemical and immunoelectron microscopic techniques with periodatelysine-paraformaldehyde (PLP) fixation, we have studied the distribution of Factor VIII-related antigen (F VIII R: Ag) in 14 cases of human central nervous system (CNS) tumors and 1 sample of non-tumor brain tissue. F VIII R: Ag was localized to the vascular lumen, to the intercellular spaces between endothelial cells (apparently without tight junctions), and to the endothelial cell basement membrane. In the cytoplasm, F VIII R: Ag was found in the endoplasmic reticulum, perinuclear space, and intracytoplasmic vacuoles and vesicles only. Characteristic of malignant tumors (6 out of 7) was strongly-positive dilated endoplasmic reticulum, whereas only 1 of 5 benign tumors showed such staining. This appears to reflect increased F VIII R: Ag synthesis in the malignant vessels. The non-tumor brain tissue showed normal capillary structure and very little F VIII R: Ag immunoreactivity. Six of 12 tumors and the non-tumor brain showed perinuclear F VIII R: Ag. Although the basement membranes were more irregular in the malignant tumors, staining was not grossly different from that of the more benign lesions. The finding of both ad-and ablumial vesicles containing F VIII R: Ag suggests that endocytosis, transcellular transport, and/or exocytosis, as well as F VIII R: Ag synthesis, occurs in the tumor endothelial cells. The relationship of these F VIII R: Ag abnormalities to the hypercoagulable state seen in some malignant brain tumor patients remains to be clarified.

Microcytotoxicity blocking assay for the detection and isolation of soluble astrocytoma association antigen

A blocking microcytotoxicity assay was used to detect soluble astrocytoma-associated antigen. The richest source of soluble antigen was found in spent culture media from an established glioblastoma (GF) tissue culture line. Also assayed were fractions of sonicated membrane antigen from another (GM) glioblastoma and pellets of GF and GM cultured glioblastoma tissue. Blocking by media conditioned by cultured normal human brain, breast cancer, neuroblastoma, meningioma, or 2-year-old astrocytoma cell lines was 41-82% lower. A monomer was isolated that blocked cytotoxicity and migrated in molecular exclusion chromatography with alpha-macroglobulins rather than the beta-2-microglobulins usually associated with histocompatibility antigens.

The beta-adrenergic receptor system in human glioma-derived cell lines: the mode of phosphodiesterase induction and the macromolecules phosphorylated by cyclic AMP-dependent protein kinase

beta-Adrenergic receptors and the activities of adenylate cyclase, phosphodiesterase and protein kinase were examined in two human glioma cell lines, U 251 and LM, as well as in rat C6 glioma. [3H]Dihydroalprenolol binding to beta-adrenergic receptors was specific, saturable and of high affinity in each cell line. The dissociation constant (Kd) and maximal binding (Bmax) extrapolated from Scatchard curves were Kd = 17.4 +/- 3.2 nM and Bmax = 1110 +/- 197 fmol/mg protein for the U-251 cells; Kd = 14.4 +/- 2.2 nM and Bmax = 655 +/- 105 fmol/mg protein for the LM cells; and Kd = 5.6 +/- 1.1 nM and Bmax = 454 +/- 80 fmol/mg protein for the C6 glioma cells. L-Isoproterenol stimulated cyclic AMP formation in all 3 cell lines. beta-Adrenergic agonists also increased calcium-dependent and calcium non-dependent phosphodiesterase activity in these tumor cells. Cytosolic protein kinase in the 3 cell lines phosphorylated exogenous histone as a substrate. The phosphorylation was enhanced by cyclic AMP. Cytosolic protein kinase also phosphorylated endogenous cytosolic macromolecules. The phosphorylated proteins had molecular weights of 30,000, 51,000 and 90,000 in the two human glioma cell lines. The present results indicate that human glioma cell lines have functional beta-adrenergic receptors linked to adenylate cyclase. These beta-receptors can also regulate phosphodiesterase activity and cyclic AMP in human glioma cells can activate protein kinase and induce the phosphorylation of specific proteins.