Antisense-mediated inhibition of the bcl-2 gene induces apoptosis in human malignant glioma

BACKGROUND

The bcl-2 protooncogene represses a number of cellular apoptotic pathways and is known to be expressed in increasing amounts in glial tumors of higher malignancy. We tested whether antisense oligonucleotides to the bcl-2 gene would affect glioma cell viability.

METHODS

Antisense oligonucleotides directed to the first six codons of the human bcl-2 gene, and nonsense oligonucleotides as a control, were transfected into malignant glioma cells. Two human Bcl-2 positive glioblastoma cell lines from our tumor bank (Jon52 and Roc) were both transfected in vitro with bcl-2 antisense (AS) and nonsense (NS) oligonucleotides at 1 microm and 5 microm concentrations for 5 and 24 hr. Cell viability was assessed at 2, 4, 5, and 7 days by using an MTT mitogenic assay and by cell counting via direct visualization using a hemocytometer.

RESULTS

There was up to a log-fold decrease in cell growth of the bcl-2 AS treated cells compared to the NS transfected cells for both Roc (p = 0.007 and p = 0.004) and Jon52 (p = 0.02 and p = 0.004) at 5 and 24 hr of transfection. There was as much as 50% cytotoxicity in both glioblastoma cell lines at 1 microm and 5 microm concentrations after 24 hr transfection with AS bcl-2 oligonucleotides (all p < 0.01). Western blot analysis demonstrated a decrease in the expression of the Bcl-2 protein in one cell line, whereas there was a statistically significant increase in the apoptotic index of both cell lines (p < 0.05 by chi square analysis).

CONCLUSIONS

Our results suggest that transfection of human glioma cells with antisense bcl-2 results in an increase in apoptotic death. This provides evidence that Bcl-2 plays a role in tumor progression of glioma by acting as an oncogene, and suggests that inhibition of the bcl-2 gene could have a therapeutic effect.

Image-injected frameless stereotactic approach to the anterior craniovertebral junction

Transoral odontoidectomy is often performed in the treatment of cervicomedullary junction disease. The operating microscope is frequently used to improve visualization in this narrow field of view. In the setting of complex anatomy or surgical revision the authors hypothesized that combining frameless stereotactic technique with intraoperative microscopy would improve the ability to visualize and identify intraoperative anatomy. In addition they believed that the ability to visualize the targeted region directly in the operating microscope "image injection" would be of particular interest in this setting, provided that sufficient accuracy for use could be obtained in the registration process. The authors assessed the efficacy of this approach in a cadaveric model and obtained sufficient accuracy to warrant use in the operating room. This technique was applied in the surgical management of a 56-year-old woman with rheumatoid arthritis who had undergone a previous decompressive transoral procedure. Subsequently she suffered progressive deterioration and was found to have residual bony compression of the anterior cervicomedullary junction. The authors performed decompressive surgery and obtained satisfactory results by using the image-injected technique, and the patient experienced subsequent clinical improvement. The authors conclude that the image-injected frameless stereotactic technique is of potential benefit, particularly in the narrow window of approach of the transoral odontoidectomy.

[Therapeutic strategy for large cervical, mediastinal metastatic mature teratomas and large retro- and intraperitoneal lesions]

A 27 years old man was treated after surgery and classic chemotherapy for a right testicular teratoma (stage IV). Two months after the end of chemotherapy the patient developed "a Growing Teratoma Syndrome" with left subclavian and mediastinal nodes enlargement and bulky abdominal cystic masses with vena cava compression, collateral circulation and oedema of inferior members. Four debulking surgical approaches: cervical, thoracic and abdominal were performed and permitted complete functional recovery.

Chemical properties of the anion transport inhibitory binding site of arginine-specific reagents in human red blood cell membranes

A series of arginine-specific reagents with different size and polarity have been synthesized and their inhibitory potency on sulfate exchange in resealed ghosts has been investigated. The synthesized phenylglyoxal derivatives p-nitro-, p-methyl-, p-hydroxy-, p-carboxy-, p-sulfo-, and p-azido-phenylglyoxal are found to be potent inhibitors of anion transport. The reaction between the cells and azidophenylglyoxal was performed in the dark. Exposure of the modified cells to the light was not followed by an increase in the inhibition. No cross-linking products were visible after gel electrophoresis. The rate of inactivation of sulfate flux with these reagents obeyed pseudo-first-order kinetics and increases with increasing reagents concentration and pH. Prolonged incubation of the cells with these reagents results in almost complete inhibition of the transport system. The positively charged phenylglyoxal derivative 4-(trimethylammonioacetylamido)phenylglyoxal was not able to inhibit the transport system. The hydrophobic character and the electronic properties of these reagents do not correlate with their inhibitory potency. Their electrostatic and steric effects seem to play the major role in their action.

Studies on inactivation of anion transport in human red blood cell membrane by reversibly and irreversibly acting arginine-specific reagents

A chromophoric derivative of phenylglyoxal, 4-hydroxy-3-nitrophenylglyoxal (HNPG), known to be highly selective for modification of arginine residues in aqueous solution is found to be a potent inhibitor of anion transport across the red cell membrane. In contrast to the action of all other arginine-specific reagents used under the experimental conditions in this laboratory, the action of HNPG on sulfate transport is completely reversible. Hence, a kinetic analysis of its inhibitory effect on SO4(2-) self-exchange could be performed. The effect of increasing chloride concentration on the inhibitory potency of HNPG is consistent with the concept that Cl- and HNPG compete for the same site on the anion transporter. The IC50 value for the inhibition of SO4(2-) exchange with HNPG is about 0.13 mM at pH 8.0 and 0.36 mM at pH 7.4, and the Hill coefficient for the interaction between the transporter and the inhibitor is near one at both pH's. HNPG is able to protect the transport system against inhibition with the (under our experimental conditions) irreversibly acting arginine specific reagent, phenylglyoxal. Partial inactivation of the transport system with phenylglyoxal lowers the maximal rates of SO4(2-) and chloride exchange but does not modify the apparent KS for the substrate anions. Reversibly acting anion transport inhibitors known to interact with the DIDS binding site like salicylate, tetrathionate, APMB, DNDS, and flufenamate are able to protect the transport system against phenylglyoxalation. Other inhibitors like phloretin and phlorizin have no effect.

New evidence for the essential role of arginine residues in anion transport across the red blood cell membrane

2,3-Butanedione, in the dark and in the presence of borate, reacts rapidly to inactivate the sulfate equilibrium exchange across the human red cell membrane. Reactivation occurs spontaneously after the removal of borate, indicating the reaction of butanedione with essential arginine residues. The inactivation of the transport system depends on the concentration of the reagent, on the incubation time and exhibits pseudo-first-order kinetics. Chloride ions are able to protect the transport system against inactivation with the reagent. This would suggest the participation of the modified residue in the substrate binding site. When the transport system is inhibited to 50-60% by butanedione, the transporter can still bind covalently the anion transport inhibitor 2H2DIDS up to 85 +/- 12% of its total binding capacity. 3H2DIDS concentration was either 3.15, 10 or 20 microM. Modification of resealed ghosts with 50 mM butanedione under conditions where the transport system is to more than 75% inhibited, causes a reduction of only about 30% of the reversibly bound 3H2DIDS.

[Effect of positive end expiratory pressure on arterial oxygenation during bronchoalveolar lavage for proteinosis]

To maintain good cellular oxygenation during bronchopulmonary lavage for alveolar proteinosis is often a difficult problem to solve. A case is reported of alveolar proteinosis in whom four lavages were performed. Details of the technique are discussed, as are the problems with expedients used to improve PaO2. The use of a 10 cmH2O positive end-expiratory pressure was useful only during the "in-phase"; in the "out-phase", it worsened the PaO2. PaO2 during lavage in patients with alveolar proteinosis can only be improved by three ways: cancellation of the shunt during lung filling and, during the "out-phase", an increase in FIO2 or pulmonary artery occlusion by a balloon.

Anion transport in red blood cells and arginine-specific reagents. Interaction between the substrate-binding site and the binding site of arginine-specific reagents

Phenylglyoxal is found to be a potent inhibitor of sulfate equilibrium exchange across the red blood cell membrane at both pH 7.4 and 8.0. The inactivation exhibits pseudo-first-order kinetics with a reaction order close to one at both pH 7.4 and 8. The rate constant of inactivation at 37 degrees C was found to be 0.12 min-1 at pH 7.4 and 0.19 min-1 at pH 8.0. Saturation kinetics are observed if the pseudo-first order rate constant of inhibition is measured as a function of phenylglyoxal concentration. Sulfate ions as well as chloride ions markedly decrease the rate of inactivation by phenylglyoxal at pH 7.4, suggesting that the modification occurs at or near to the binding site for chloride and sulfate. The decrease of the rate of inactivation produced at pH 8.0 by chloride ions is much higher than that produced by sulfate ions. Kinetic analysis of the protection experiments showed that the loaded transport site is unable to react with phenylglyoxal. From the data it is concluded that the modified amino acid(s) residues, presumably arginine, is (are) important for the binding of the substrate anion.