A phase I study of intravenous oncolytic reovirus type 3 Dearing in patients with advanced cancer

PURPOSE

To determine the safety and feasibility of daily i.v. administration of wild-type oncolytic reovirus (type 3 Dearing) to patients with advanced cancer, assess viral excretion kinetics and antiviral immune responses, identify tumor localization and replication, and describe antitumor activity.

EXPERIMENTAL DESIGN

Patients received escalating doses of reovirus up to 3 x 10(10) TCID(50) for 5 consecutive days every 4 weeks. Viral excretion was assessed by reverse transcription-PCR and antibody response by cytotoxicity neutralization assay. Pretreatment and post-treatment tumor biopsies were obtained to measure viral uptake and replication.

RESULTS

Thirty-three patients received 76 courses of reovirus from 1 x 10(8) for 1 day up to 3 x 10(10) TCID(50) for 5 days, repeated every four weeks. Dose-limiting toxicity was not seen. Common grade 1 to 2 toxicities included fever, fatigue, and headache, which were dose and cycle independent. Viral excretion at day 15 was not detected by reverse transcription-PCR at 25 cycles and only in 5 patients at 35 cycles. Neutralizing antibodies were detected in all patients and peaked at 4 weeks. Viral localization and replication in tumor biopsies were confirmed in 3 patients. Antitumor activity was seen by radiologic and tumor marker (carcinoembryonic antigen, CA19.9, and prostate-specific antigen) evaluation.

CONCLUSIONS

Oncolytic reovirus can be safely and repeatedly administered by i.v. injection at doses up to 3 x 10(10) TCID(50) for 5 days every 4 weeks without evidence of severe toxicities. Productive reoviral infection of metastatic tumor deposits was confirmed. Reovirus is a safe agent that warrants further evaluation in phase II studies.

Inflammatory tumour cell killing by oncolytic reovirus for the treatment of melanoma

Reovirus is a promising unmodified double-stranded RNA (dsRNA) anti-cancer oncolytic virus, which is thought to specifically target cells with activated Ras. Although reovirus has been tested in a wide range of preclinical models and has entered early clinical trials, it has not previously been tested for the treatment of human melanoma. Here, we show that reovirus effectively kills and replicates in both human melanoma cell lines and freshly resected tumour; intratumoural injection also causes regression of melanoma in a xenograft in vivo model. Reovirus-induced melanoma death is blocked by caspase inhibition and is dependent on constituents of the Ras/RalGEF/p38 pathway. Reovirus melanoma killing is more potent than, and distinct from, chemotherapy or radiotherapy-induced cell death; a range of inflammatory cytokines and chemokines are released by infected tumour cells, while IL-10 secretion is abrogated. Furthermore, the inflammatory response generated by reovirus-infected tumour cells causes bystander toxicity against reovirus-resistant tumour cells and activates human myeloid dendritic cells (DC) in vitro. Hence, reovirus is suitable for clinical testing in melanoma, and may provide a useful danger signal to reverse the immunologically suppressive environment characteristic of this tumour.

Radiation-mediated up-regulation of gene expression from replication-defective adenoviral vectors: implications for sodium iodide symporter gene therapy

PURPOSE

To assess the effects of external beam radiotherapy (EBRT) on adenoviral-mediated transgene expression in vitro and in vivo and to define an optimal strategy for combining sodium iodide symporter (NIS)-mediated (131)I therapy with EBRT.

EXPERIMENTAL DESIGN

Expression of reporter genes [NIS, green fluorescent protein (GFP), beta-galactosidase (lacZ), and luciferase (Luc)] from replication-deficient adenoviruses was assessed in tumor cell lines under basal conditions and following irradiation. The effects of viral multiplicity of infection (MOI) and EBRT dose on the magnitude and duration of gene expression were determined. In vivo studies were done with Ad-CMV-GFP and Ad-RSV-Luc.

RESULTS

EBRT increased NIS, GFP, and beta-galactosidase expression in colorectal, head and neck, and lung cancer cells. Radiation dose and MOI were important determinants of response to EBRT, with greatest effects at higher EBRT doses and lower MOIs. Radiation exerted both transductional (through increased coxsackie-adenoviral receptor and integrin alpha(v)) and nontransductional effects, irrespective of promoter sequence (CMV, RSV, hTR, or hTERT). Analysis of the schedule of EBRT followed by viral infection revealed maximal transduction at 24 hours. Radiation maintained increasing radioiodide uptake from Ad-hTR-NIS over 6 days, in direct contrast to reducing levels in unirradiated cells. The effects of EBRT in increasing and maintaining adenovirus-mediated transgene expression were also seen in vivo using GFP- and luciferase-expressing adenoviral vectors.

CONCLUSIONS

Radiation increased the magnitude and duration of NIS gene expression from replication-deficient adenoviruses. The transductional effect is maximal at 24 hours, but radioiodide uptake is maintained at an elevated level over 6 days after infection.

Enhanced in vitro and in vivo cytotoxicity of combined reovirus and radiotherapy

PURPOSE

To test combination treatment schedules of reovirus and radiation in human and murine tumor cells in vitro and in vivo.

EXPERIMENTAL DESIGN

In vitro cytotoxicity and cell cycle effects of reovirus given alone and combined with radiotherapy were assessed by colorimetric, tissue culture infectious dose 50, and fluorescence-activated cell sorting-based assays. Interactions between the agents were evaluated using combination index analysis. The effect of different schedules of reovirus and radiotherapy on viral replication and cytotoxicity was tested in vitro and the combination was assessed in three tumor models in vivo.

RESULTS

Characterization of reovirus cytotoxicity in a panel of cell lines yielded a range of sensitivities. Combined reovirus and radiotherapy yielded statistically significantly increased cytotoxicity, particularly in cell lines with moderate susceptibility to reovirus alone. The enhanced cytotoxicity of the combination occurred independently of treatment sequence or schedule. Radiation did not affect viral replication and only reduced reoviral cytotoxicity after clinically irrelevant single doses (>50 Gy). Combination index analysis revealed synergy between radiation (3-10 Gy) and reovirus at multiplicities of infection between 0.001 and 1. Combination treatment significantly increased apoptosis in tumor cells relative to either single-agent treatment. In vivo studies using xenograft and syngeneic tumors showed enhanced activity of the combination relative to reovirus or radiation alone (P < 0.001).

CONCLUSIONS

Combining reovirus and radiotherapy synergistically enhances cytotoxicity in a variety of tumor cells in vitro and in vivo. These results offer strong support for translational clinical trials of reovirus plus radiotherapy that have been initiated in the clinic.

Escherichia coli nitroreductase plus CB1954 enhances the effect of radiotherapy in vitro and in vivo

Escherichia coli nitroreductase (NTR) converts the prodrug CB1954 (5-(aziridin-1-yl)-2,4-dinitrobenzamide) into a bifunctional alkylating agent that causes DNA crosslinks. In this study, the ability of NTR to enhance the combined effects of CB1954 and radiation has been tested in vitro and in vivo. Stably transduced ovarian cancer cells (SKOV3-NTR) that are sensitive to CB1954 (IC(50)=0.35 muM) demonstrated enhanced cytotoxicity when treated with CB1954 and single-fraction irradiation. The NTR-CB1954 system mediated a bystander effect in combination with radiation on transfer of conditioned medium from SKOV3-NTR, but not SKOV3, cells to SW480 target cells. The ability of CB1954 to enhance radiation-induced cytotoxicity in SKOV3-NTR (but not SKOV3) cells was also demonstrated by fluorescence-activated cell sorting (FACS) with dual staining for propidium iodide/fluorescein diacetate, 4',6-diamidino-2-phenylindole dichloride staining of apoptotic cells and measurement of double-stranded DNA breaks by FACS and confocal microscopy for gammaH2AX foci. Adenoviral delivery of NTR, under constitutive cytomegalovirus or tissue-specific CTP1 promoters, increased the in vitro cytotoxicity of CB1954 plus radiation in MTT and clonogenic assays. Finally, adenoviral delivery of NTR plus CB1954 enhanced the effect of fractionated radiotherapy (12 Gy in four fractions) in SW480 xenograft tumours in nude mice.

Enlarged spleens without enlarged lymph nodes in tlr3-/- pkr-/- mice

Initial phenotypic studies in a mouse containing mutations in both toll-like receptor 3 (TLR3) and RNA-de-pendent protein kinase R (PKR) revealed comparable spleen and bone marrow cell populations in tlr3(-/)-, pkr(-/-), and tlr3(-/-)pkr(-/-) mice to wild-type controls. Splenomegaly developing between 8 and 10 weeks of age was observed in tlr3(-/-) and tlr3(-/-)pkr(-/-) mice but not in wild-type or pkr(-/-) mice. Palpably enlarged cervical, axillary, and inguinal lymph nodes accompanied by enlarged spleens were observed in 12-18-week-old tlr3(-/-) mice at a higher frequency compared with other genotypes. The enlarged spleens and lymph nodes observed in tlr3(-/-) mice were accompanied by destruction of organ architecture and lymphocyte infiltration. However, the enlargement of these organs was not the result of clonal proliferation of one lymphocyte subset. It is likely this phenotype is a result of TLR3 deficiency in combination with an additional, uncharacterized genetic defect or the presence of an infectious agent. These data also suggest that PKR may have a role in preventing progression from splenomegaly to lymphadenopathy in these mice.

Probing colloidal forces between a Si3N4 AFM tip and single nanoparticles of silica and alumina

The atomic force microscope (AFM) has been used to measure surface forces between silicon nitride AFM tips and individual nanoparticles deposited on substrates in 10(-4) and 10(-2) M KCl solutions. Silica nanoparticles (10 nm diameter) were deposited on an alumina substrate and alumina particles (5 to 80 nm diameter) were deposited on a mica substrate using aqueous suspensions. Ionic concentrations and pH were used to manage attractive substrate-particle electrostatic forces. The AFM tip was located on deposited nanoparticles using an operator controlled offset to achieve stepwise tip movements. Nanoparticles were found to have a negligible effect on long-range tip-substrate interactions, however, the forces between the tip and nanoparticle were detectable at small separations. Exponentially increasing short-range repulsive forces, attributed to the hydration forces, were observed for silica nanoparticles. The effective range of hydration forces was found to be 2-3 nm with the decay length of 0.8-1.3 nm. These parameters are in a good agreement with the results reported for macroscopic surfaces of silica obtained using the surface force apparatus suggesting that hydration forces for the silica nanoparticles are similar to those for flat silica surfaces. Hydration forces were not observed for either alumina substrates or alumina nanoparticles in both 10(-4) M KCl solution at pH 6.5 and 10(-2) M KCl at pH 10.2. Instead, strong attractive forces between the silicon nitride tip and the alumina (nanoparticles and substrate) were observed.

Effect of a selective OX1R antagonist on food intake and body weight in two strains of rats that differ in susceptibility to dietary-induced obesity

An orexin-1 receptor antagonist decreases food intake whereas orexin-A selectively induces hyperphagia to a high-fat diet. In the present study, we evaluated the effect of an orexin antagonist in two strains of rats that differ in their sensitivity to becoming obese while eating a high-fat diet. Male Osborne-Mendel (OM) and S5B/Pl (S5B) rats were treated acutely with an orexin-1 receptor antagonist (SB-334867), after adaptation to either a high-fat (56% fat energy) diet or a low-fat (10% fat energy) diet that were equicaloric for protein (24% energy). Ad libitum fed rats were injected intraperitoneally with SB-334867 at doses of 3, 10 or 30 mg/kg, or vehicle at the beginning of the dark cycle, and food intake and body weight were measured. Hypothalamic prepro-orexin and orexin-1 receptor mRNA expression were analyzed in OM and S5B rats fed at a high-fat or low-fat diet for two weeks. SB-334867 significantly decreased food intake in both strains of rats eating the high-fat diet but only in the OM rats eating the low fat diet. The effect was greatest at 12 and 24 h. Body weight was also reduced in OM rats 1d after injection of SB-334867 but not in the S5B rats. Prepro-orexin and orexin-1 receptor expression levels did not differ between strains or diets. These experiments demonstrate that an orexin antagonist (SB-334867) reduces food intake and has a greater effect in a rat strain that is susceptible to dietary-induced obesity, than in a resistant strain.

Physical and immunological characterization of a recombinant secreted form of the membrane protein encoded by the vaccinia virus L1R gene

We reported that immunization with recombinant proteins derived from vaccinia virus (VV) particles could provide protection against infection. Here we describe the physical and antigenic properties of the L1R membrane protein. The recombinant protein (L1R(185t)) was secreted as a monomer and correct folding was suggested by the presence of three intramolecular disulfide bonds and binding to conformation-specific monoclonal antibodies (MAbs). Furthermore, anti-L1R(185t) rabbit antisera exhibited potent virus-neutralizing activity against the IMV form of VV. We raised six MAbs against L1R(185t). Three recognized linear epitopes (residues 118--128) and neutralized IMV infectivity. These MAbs blocked binding of each other to L1R(185t) but failed to block binding of two previously described neutralizing anti-L1R MAbs, 7D11 and 2D5. The latter two antibodies blocked each other in binding L1R(185t). Thus, two antigenic sites on L1R overlap functional domains and based on recent structural studies these are found in accessible regions of the IMV L1R protein.

Most cases of dementia with hippocampal sclerosis may represent frontotemporal dementia

Hippocampal sclerosis dementia (HSD) is a disease of unknown etiology and pathogenesis. To determine whether HSD cases could be reclassified as variants of frontotemporal dementia (FTD), a heterogeneous group of disorders, 18 brain autopsy cases previously diagnosed as HSD were re-evaluated. In 11 cases, ubiquitinated neuronal inclusions, similar to those of motor neuron disease inclusion dementia (MNDID), were found. Brain levels of soluble and insoluble tau were normal. Most patients with pathologic findings of HSD may actually have the MNDID variant of FTD.

Frontotemporal and motor neurone degeneration with neurofilament inclusion bodies: additional evidence for overlap between FTD and ALS

We present the case of a patient who had clinical frontal lobe dementia without apparent motor neurone disease (MND), with pathologic findings not typical of any single currently classified frontotemporal degeneration (FTD). At autopsy, the brain had frontal and temporal atrophy with neuronal loss, gliosis, and superficial spongiosis, typical of all FTDs. There were at least three different morphologic types of intracytoplasmic neuronal inclusions in a variety of brain and brainstem regions, including the hippocampal dentate gyrus and pyramidal neurones, the neocortex (in particular, the motor cortex), basal ganglia, thalamus, subthalamic nucleus, basis pontis, and inferior olivary nuclei. Inclusions had the morphologies of Pick-like bodies, pleomorphic inclusions, and hyaline conglomerate (HC)-like inclusions. None of these were positive with tau immunostains. Pick-like bodies in the dentate gyrus were labelled with ubiquitin. The pleomorphic inclusions in the neocortex and dentate gyrus and the HC-like inclusions in the motor and parietal cortex were strongly positive with immunostains for neurofilament. We discuss the differential diagnosis and compare this case with those disorders to which it is most similar. In particular, we compare the unique neurofilament-positive inclusions to the inclusions of FTD-MND, to Pick bodies, and to the basophilic and HC inclusions that are occasionally seen in amytrophic lateral sclerosis (ALS). Although FTD-MND may be found in ALS, the findings in this case may have additional implications for a link between FTD and ALS.

Expression of the vaccinia virus A2.5L redox protein is required for virion morphogenesis

In this article we report the initial biochemical, genetic, and electron microscopic analysis of a previously uncharacterized, 8.9-kDa, predicted thiol-redox protein. The name A2.5L was assigned to the corresponding vaccinia virus gene, which is conserved in all sequenced poxviruses. Multiple alignment analysis and secondary structure prediction indicated that the A2.5L gene product is an all-alpha-helical protein with a conserved Cxx(x)C motif in the N-terminal alpha-helix. The DNA replication requirement and kinetics of A2.5L protein accumulation in virus-infected cells were typical of a late gene product, in agreement with the predicted promoter sequence. The A2.5L protein was a monomer under reducing conditions, but was mostly associated with the vaccinia virus E10R redox protein as a heterodimer under nonreducing conditions. The A2.5L protein was detected in virus particles at various stages of assembly, suggesting that it is an integral component of intracellular virions. An inducer-dependent A2.5L null mutant was constructed: in the absence of inducer, infectious virus formation was abolished and electron microscopy revealed an assembly block with an accumulation of crescent membranes and immature virions. This stage of assembly block was similar to that occurring when the E10R and G4L redox proteins were repressed, which is compatible with the involvement of E10R, A2.5L, and G4L in the same redox pathway.

Synapse loss is greater in presenile than senile onset Alzheimer disease: implications for the cognitive reserve hypothesis

In the past, 'Alzheimer disease' (AD) referred to pathologic AD with clinical onset of dementia in the presenium, while 'senile dementia of the Alzheimer type' (SDAT) referred to senile onset AD. Because AD appears clinically homogeneous regardless of age of onset, the two subtypes in more recent years have not been distinguished. Pathologic differences have been noted, but synapse loss has not previously been compared between the two groups. Hypothesizing that synapse loss would be greater in presenile onset than senile onset AD, we compared synapse loss, as well as Alzheimer pathology in presenile and senile onset AD, using an ELISA method to quantify synaptophysin. Synaptophysin was significantly lower in presenile than senile AD in right frontal and bilateral parietal lobes. Neuritic plaque counts were significantly higher in presenile than senile AD in bilateral frontal and parietal lobes. Semi-quantitative evaluation of neurofibrillary tangles revealed significantly more tangles in bilateral frontal and parietal lobes in presenile than senile AD. Brain weight was significantly lower in presenile than senile AD. The differences in synapse loss and Alzheimer-type pathology in presenile and senile onset AD support the hypothesis that 'cognitive reserve' protects the human brain from neurodegenerative disease.

Complete pathway for protein disulfide bond formation encoded by poxviruses

We show that three cytoplasmic thiol oxidoreductases encoded by vaccinia virus comprise a complete pathway for formation of disulfide bonds in intracellular virion membrane proteins. The pathway was defined by analyzing conditional lethal mutants and effects of cysteine to serine substitutions and by trapping disulfide-bonded heterodimer intermediates for each consecutive step. The upstream component, E10R, belongs to the ERV1/ALR family of FAD-containing sulfhydryl oxidases that use oxygen as the electron acceptor. The second component, A2.5L, is a small alpha-helical protein with a CxxxC motif that forms a stable disulfide-linked heterodimer with E10R and a transient disulfide-linked complex with the third component, G4L. The latter is a thioredoxin-like protein that directly oxidizes thiols of L1R, a structural component of the virion membrane with three stable disulfide bonds, and of the related protein F9L. These five proteins are conserved in all poxviruses, suggesting that the pathway is an ancestral mechanism for direct thiol-disulfide interchanges between proteins even in an unfavorable reducing environment.

Vaccinia virus G4L glutaredoxin is an essential intermediate of a cytoplasmic disulfide bond pathway required for virion assembly

Our previous studies provided evidence that E10R, a vaccinia virus protein belonging to the ERV1/ALR family, has a redox function and is required for virion assembly. Repression of E10R prevented the formation of intramolecular disulfide bonds of the G4L glutaredoxin, the L1R membrane protein, and the structurally related F9L protein. Here, we demonstrate an oxidation pathway (E10R(SS) --> G4L(SS) --> L1R(SS), F9L(SS)) in which G4L occupies an intermediate position. By reacting free thiols with 4-acetamido-4'-malemideylstilbene-2,2'-disulfonic acid, alkylated and nonalkylated disulfide-bonded forms of G4L could be resolved from each other by polyacrylamide gel electrophoresis. The cysteines of intracellular G4L were in both disulfide and reduced forms, whereas those of E10R, L1R, and F9L and virion-associated G4L were mostly disulfide bonded. Repression of G4L expression prevented the formation of disulfide bonds in both L1R and F9L but not E10R. Both cysteines of G4L were required for L1R and F9L disulfide bond formation or for trans-complementation of virus infectivity when G4L expression was repressed. No role in the E10R-G4L redox pathway was found for O2L, a nonessential glutaredoxin encoded by vaccinia virus. We suggest that cytoplasmic G4L is a redox shuttle between membrane-associated E10R and L1R or F9L.

Continuity of care for short-stay neurosurgery patients: a quality improvement initiative

Decreases in the length of hospital stay for patients undergoing spinal surgery prompted this evaluation of the post-discharge needs of patients and the strategies that patients and their families employ to meet these needs. The nature and extent of post-discharge problems experienced by newly discharged patients was required as a baseline for the evaluation and improvement of discharge planning. Forty patients were interviewed following discharge, 20 patients within the first week of discharge, and 20 different patients between three and four weeks after discharge. Most patients reported that they had been well-informed about pain management and the majority of patients reported that pain was well-controlled. There was a subset of patients, however, who continued to report high levels of pain, even at one month after discharge. Less than one in three patients stated that they had received information about wound care and the information received was not consistent among health professionals. Given the limited time to prepare patients for discharge, this project highlights the need for written materials and for systematic follow-up after discharge.

Contribution of asymmetric synapse loss to lateralizing clinical deficits in frontotemporal dementias

BACKGROUND

Synapse loss has been found to be the major correlate of cognitive decline in Alzheimer disease (AD), and prefrontal synapse loss has been found in patients with frontotemporal dementia (FTD).

OBJECTIVE

To see if our hypothesis that within each FTD case, regional synapse loss would correlate with lateralizing neuropsychologic and neurobehavioral deficits would be correct.

DESIGN

We analyzed synaptophysin as a marker for synapse loss in snap-frozen brain samples, using an enzyme-linked immunosorbent assay technique. Quantitative results were obtained by comparing patient data with a standard curve made by analyzing serial dilutions of a recombinant synaptophysin protein fragment. A board-certified neuropsychologist and a board-certified neurologist, both unaware of the synaptophysin results, determined areas of primary neuropsychologic and neurobehavioral dysfunction. Relationships between areas of primary dysfunction and synapse loss were analyzed using the binomial test.

PATIENTS

Six cases of FTD, 28 cases of AD, and 16 nondemented control subjects.

RESULTS

Five of 6 FTD cases had regional synaptophysins correlating with lateralizing frontal or temporal deficits. Three of 6 correlated in 2 or more regions. Although our results were higher than that expected based on a pure-chance mechanism (50% vs 34%), statistical significance was not attained.

CONCLUSIONS

We found a trend for an association between synapse loss and lateralizing neuropsychologic and neurobehavioral deficits in FTD. Studies in larger numbers of FTD cases are planned with the goal of attaining statistically significant conclusions.

Cortical synapse loss in progressive supranuclear palsy

Cortical synapse loss, the probable substrate of cognitive impairment in Alzheimer disease (AD), has not previously been evaluated in progressive supranuclear palsy (PSP). Hypothesizing that synapse loss would be greater in demented than non-demented PSP patients, we examined synaptophysin concentrations in 8 cases of PSP (5 demented and 3 nondemented cases). We found a decrease in mean synaptophysin concentration in these 8 cases in frontal, temporal, and parietal lobes, and in cerebellum, compared to the means in corresponding lobes of 16 controls. The decreases were similar to those in 28 cases of AD, but not as great. We determined synaptophysin concentration from motor cortex in only 4 of our PSP cases, 2 demented and 2 non-demented. The average concentrations in these 4 cases were lower than in AD motor cortex; both were lower than controls. When demented and non-demented PSP cases were compared, neocortical synaptophysin concentrations in non-demented PSP cases were lower than in demented cases. There appears to be a link between AD and PSP, in that synapse loss is found in both. However, the basis and significance of the prominent neocortical synapse loss in PSP, especially in non-demented subjects, remain to be explored.

Frontal lobe dementia with novel tauopathy: sporadic multiple system tauopathy with dementia

We present a novel tauopathy in a patient with a 10-yr history of progressive frontal lobe dementia and a negative family history. Autopsy revealed mild atrophy of frontal and parietal lobes and severe atrophy of the temporal lobes. There were occasional filamentous tau-positive inclusions, but more interesting were numerous distinctive globular neuronal and glial tau-positive inclusions in both gray and white matter of the neocortex. Affected subcortical regions included substantia nigra, globus pallidus, subthalamic nucleus, and cerebellar dentate nucleus, in a distribution similar to progressive supranuclear palsy (PSP), but without significant accompanying neuronal loss or gliosis. Predominantly straight filaments were detected by electron microscopy (EM), while other inclusions were similar to fingerprint bodies. No twisted ribbons were detected. Immuno-EM studies revealed that only the filamentous inclusions were composed of tau. Immunoblotting of sarkosyl-insoluble tau revealed 2 major bands of 64 and 68 kDa. Blotting analysis after dephosphorylation revealed predominantly 4-repeat tau. Sequence analysis of tau revealed that there were no mutations in either exons 9-13 or the adjacent intronic sequences. The unique cortical tau pathology in this case of sporadic multiple system tauopathy with dementia adds a new pathologic profile to the spectrum of tauopathies.

Recurrent (nonfamilial) hemangioblastomas involving spinal nerve roots: case report

OBJECTIVE AND IMPORTANCE

Spinal nerve root hemangioblastomas are rare and are reported mainly in patients with von Hippel-Lindau (VHL) syndrome. The pathogenesis of so-called nonfamilial lesions is virtually unknown. We discuss, mainly from a molecular perspective, a unique patient with sporadic, recurrent hemangioblastomas restricted to spinal nerve roots.

CLINICAL PRESENTATION

A 53-year-old man who had had a surgically corrected lumbosacral meningomyelocele presented on at least three occasions during a 17-year period with multifocal capillary hemangioblastomas involving spinal nerve roots. On each occasion, tumors appeared on a different nerve root, with the majority located in the midcervical segments. The patient had no clinical features or family history of VHL syndrome.

TECHNIQUE

To obtain a clearer understanding of the pathogenesis of this unusual case and its relationship to VHL syndrome, molecular analysis of the VHL gene was performed by use of complete sequence analysis and loss of heterozygosity studies on deoxyribonucleic acid derived from the patient's blood leukocytes and three separately resected hemangioblastomas.

CONCLUSION

Germ-line molecular analysis performed on all three exons in the VHL gene coding region did not indicate that any mutations were present. Loss of heterozygosity analysis of deoxyribonucleic acid from the three hemangioblastoma resections showed normal heterozygosity in the 3p25-26 region. Complete VHL gene sequence analysis did not demonstrate a somatic mutation in the coding region of the VHL gene in any of the three tumors, thereby supporting the loss of heterozygosity data that a molecular event directly involving the VHL gene may not be the causative factor in their tumorigenesis.

Reduced binding of protein phosphatase 2A to tau protein with frontotemporal dementia and parkinsonism linked to chromosome 17 mutations

Coding region and intronic mutations in the tau gene cause frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17). We have previously reported that ABalphaC, a major form of protein phosphatase 2A (PP2A) in brain, binds tightly to tau protein in vitro and is a major tau phosphatase in vivo. Using in vitro assays, we show here that the FTDP-17 mutations G272V, DeltaK280, P301L, P301S, S305N, V337M, G389R, and R406W inhibit by approximately 20-95% the binding of recombinant three-repeat and four-repeat tau isoforms to the ABalphaC holoenzyme and the AC core enzyme of PP2A. Reduction in binding was maximal for tau proteins with the G272V, DeltaK280, and V337M mutations. We also show that tau protein can be specifically coimmunoprecipitated with endogenous PP2A from both rat brain and transfected cell extracts. It is significant that, by using similar coimmunoprecipitation assays, we show that all FTDP-17 mutations tested, including the N279K mutation, alter the ability of tau to associate with cellular PP2A. Taken together, these results indicate that FTDP-17 mutations induce a significant decrease in the binding affinity of tau for PP2A in vivo. We propose that altered protein-protein interactions between PP2A and tau may contribute to FTDP-17 pathogenesis.

A viral member of the ERV1/ALR protein family participates in a cytoplasmic pathway of disulfide bond formation

Proteins of the ERV1/ALR family are encoded by all eukaryotes and cytoplasmic DNA viruses for which substantial sequence information is available. Nevertheless, the roles of these proteins are imprecisely known. Multiple alignments of ERV1/ALR proteins indicated an invariant C-X-X-C motif, but no similarity to the thioredoxin fold was revealed by secondary structure predictions. We chose a virus model to investigate the role of these proteins as thiol oxidoreductases. When cells were infected with a mutant vaccinia virus in which the E10R gene encoding an ERV1/ALR family protein was repressed, the disulfide bonds of three other viral proteins-namely, the L1R and F9L proteins and the G4L glutaredoxin-were completely reduced. The same outcome occurred when Cys-43 or Cys-46, the putative redox cysteines of the E10R protein, was mutated to serine. These two cysteines were disulfide bonded during a normal virus infection but not if the synthesis of other viral late proteins was inhibited or the E10R protein was expressed by itself in uninfected cells, suggesting a requirement for an upstream viral thiol oxidoreductase. Remarkably, the cysteine-containing domains of the E10R and L1R viral membrane proteins and the glutaredoxin are in the cytoplasm, in which assembly of vaccinia virions occurs, rather than in the oxidizing environment of the endoplasmic reticulum. These data indicated a viral pathway of disulfide bond formation in which the E10R protein has a central role. By extension, the ERV1/ALR family may represent a ubiquitous class of cellular thiol oxidoreductases that interact with glutaredoxins or thioredoxins.

A glutaredoxin, encoded by the G4L gene of vaccinia virus, is essential for virion morphogenesis

Vaccinia virus encodes two glutaredoxins, O2L and G4L, both of which exhibit thioltransferase and dehydroascorbate reductase activities in vitro. Although O2L was previously found to be dispensable for virus replication, we now show that G4L is necessary for virion morphogenesis. RNase protection and Western blotting assays indicated that G4L was expressed at late times after infection and was incorporated into mature virus particles. Attempts to isolate a mutant virus with a deleted G4L gene were unsuccessful, suggesting that the protein was required for virus replication. This interpretation was confirmed by the construction and characterization of a conditional lethal recombinant virus with an inducible copy of the G4L gene replacing the original one. Expression of G4L was proportional to the concentration of inducer, and the amount of glutaredoxin could be varied from barely detectable to greater than normal amounts of protein. Immunogold labeling revealed that the induced G4L protein was associated with immature and mature virions and adjacent cytoplasmic depots. In the absence of inducer, the production of infectious virus was severely inhibited, though viral late protein synthesis appeared unaffected except for decreased maturation-dependent proteolytic processing of certain core components. Electron microscopy of cells infected under nonpermissive conditions revealed an accumulation of crescent membranes on the periphery of electron-dense globular masses but few mature particles. We concluded that the two glutaredoxin homologs encoded by vaccinia virus have different functions and that G4L has a role in virion morphogenesis, perhaps by acting as a redox protein.