Single nucleotide polymorphism 309 affects murin-double-minute 2 protein expression but not glioma tumorigenesis.

Murin-double-minute 2 (MDM2) is an important negative regulator of the p53 tumor suppressor, and affects the p53 protein level and transcriptional activity. The genotype of the single nucleotide polymorphism in the promoter region of MDM2 (single nucleotide polymorphism [SNP] 309) is associated with the MDM2 protein expression level and the onset age of several types of cancer. The SNP309 genotype was investigated in 254 Japanese patients with glioma and 50 healthy subjects. The genotype frequency of SNP309 was T/T homozygous in 62 patients (24%), T/G heterozygous in 126 (50%), and G/G homozygous in 66 (26%) of the glioma patients, and was similar in the healthy subjects. The G/G ratio was higher in our Japanese subjects than in Western populations. Immunohistochemical study of glioma tissues showed that the G/G genotype was associated with higher expression of MDM2 protein compared to the T/T genotype, suggesting that SNP309 attenuates MDM2 protein expression in vivo. However, no association was found between the SNP309 genotype and the histological grade of glioma, age at disease onset, or p53 gene mutation rate. In our study population, SNP309 affected MDM2 protein level, but had no significant involvement in glioma tumorigenesis.

Sellar repair with resorbable polyglactin acid sheet and fibrin glue in endoscopic endonasal transsphenoidal surgery.

BACKGROUND: Cerebrospinal fluid leakage after transsphenoidal surgery represents a serious problem. Various methods to prevent postoperative CSF leakage are available, but immediate and tight dural closure is still difficult. The efficacy of a novel sellar repair was described. METHODS: The sellar repair using absorbable PGA sheet and fibrin glue was applied to 18 consecutive patients with sellar tumors that include 13 pituitary adenomas, 2 craniopharyngiomas, 2 Rathke's cleft cysts, and 1 meningioma within 135 patients who were treated with endoscopic endonasal transsphenoidal approach. The reaction speed and strength between PGA sheets and fibrin glue were examined in vitro. RESULTS: Polyglactin acid sheets were adhered to the rabbit skin with fibrin glue within 3 minutes and withstood a pressure of more than 220 mm Hg. Postoperative CSF leakage of the patients was not observed in any patients, and excellent adhesion of the PGA sheets to surrounding mucosa was estimated by endoscopic observation after the surgery. CONCLUSIONS: Repair of the sellar floor with PGA sheet and fibrin glue is a safe and effective method to prevent postoperative CSF leakage, which decreases the necessity for lumbar drainage after the operation.

Hyperphosphorylation at serine 199/202 of tau factor in the gerbil hippocampus after transient forebrain ischemia.

We examined the phosphorylation state of tau factor in hippocampal delayed neuronal death (DND) after transient forebrain ischemia. A transient phosphorylation increase at serine 199/202 but not serine 396 of tau factor after transient ischemia was clearly observed. Intraventricular injections of olomoucine and U-0126 (CDK5 and MAP kinase inhibitors, respectively) inhibited hyperphosphorylation. In contrast, wortmannin (PI3 kinase inhibitor) increased phosphorylation at serine 199/202 and corresponded with an increase in GSK3 phosphorylation. Our findings suggest that CDK5, MAP kinase, and GSK3 phosphorylate these sites after ischemia. We prepared recombinant normal human tau (N-Tau40) with TAT-HA protein and dephosphorylated-form human Tau-40 (D-tau40) in which 199/202 serines were changed to alanine by site-directed mutagenesis. Intraventricularly injected D-tau40 protected somewhat against DND while N-Tau40 did not. These data suggest that hyperphosphorylation at serine 199/202 of tau factor is induced by MAP kinase, CDK5, and GSK3, and contributes to ischemic neuronal injury.

Third ventricular ependymal cyst presenting with acute hydrocephalus.

Ependymal cysts are generally located in the cerebral parenchyma but rarely found in the third ventricle. A 4-year-old boy presented with headache, vomiting, and upward gaze palsy. His consciousness gradually deteriorated in the course of 6 h. A magnetic resonance imaging study disclosed dilation of the lateral ventricle and a cystic mass in the third ventricle. We performed an endoscopic resection of the cyst wall. The cyst originated on the lateral wall of the third ventricle and obstructed the aqueduct. Histological examination confirmed a diagnosis of ependymal cyst. The patient recovered quickly and his headache and nausea disappeared. Third ventricular ependymal cysts are a rare cause of acute hydrocephalus but an important differential diagnosis. Their neuroendoscopic resection can resolve disturbances in cerebrospinal fluid circulation, is useful for cyst wall removal, and appears to be superior to shunt placement.

Identification of a specific domain responsible for JNK2alpha2 autophosphorylation.

c-Jun N-terminal kinases (JNKs) are a group of mitogen-activated protein kinase family members that are important in regulating cell growth, proliferation, and apoptosis. Activation of the JNK pathway has been implicated in the formation of several human tumors. We have previously demonstrated that a 55-kDa JNK isoform is constitutively activated in 86% of human brain tumors and more recently demonstrated that this isoform is either JNK2alpha2 or JNK2beta2. Importantly, we have also found that among the 10 known JNK isoforms, the JNK2 isoforms are unique in their ability to autophosphorylate in vitro and in vivo. This does not require the participation of any upstream kinases and also leads to substrate kinase activity in vitro and in vivo. To clarify the mechanism of JNK2alpha2 autoactivation, we have generated a series of chimeric cDNAs joining portions of JNK1alpha2, which does not have detectable autophosphorylation activity, with portions of JNK2alpha2, which has the strongest autophosphorylation activity. Through in vivo and in vitro kinase assays, we were able to define a domain ranging from amino acids 218 to 226 within JNK2alpha2 that is required for its autophosphorylation. Mutation of JNK2alpha2 to its counterpart of JNK1alpha2 in this region abrogated the autophosphorylation activity and c-Jun substrate kinase activity in vivo and in vitro. Notably, switching of JNK1alpha2 to JNK2alpha2 at this 9-amino acid site enabled JNK1alpha2 to gain the autophosphorylation activity in vivo and in vitro. We also found two other functional sites that participate in JNK2alpha2 activity. One site ranging from amino acids 363 to 382 of JNK2alpha2 is required for efficient c-Jun binding in vitro, and a site ranging from amino acids 383 to 424 enhances autophosphorylation intensity, although it is not required for triggering the autophosphorylation in vitro. These findings have uncovered the regions required for JNK2alpha2 autophosphorylation, and this information could be used as potential targets to block JNK2alpha2 activation.

The influence of sex and the presence of giant cells on postoperative long-term survival in adult patients with supratentorial glioblastoma multiforme.

OBJECT: Glioblastoma multiforme (GBM) remains incurable by conventional treatments, although some patients experience long-term survival. A younger age, a higher Karnofsky Performance Scale (KPS) score, more aggressive treatment, and long progression-free intervals have been reported to be positively associated with long-term postoperative patient survival. The aim of this retrospective study was the identification of additional favorable prognostic factors affecting long-term survival in surgically treated adult patients with supratentorial GBM. METHODS: Of 113 adult patients newly diagnosed with histologically verified supratentorial GBM who were enrolled in Phase III trials during the period between 1987 and 1998, six (5.3%) who survived for longer than 5 years were defined as long-term survivors, whereas the remaining 107 patients served as controls. All six were women and were compared with the controls; they were younger (mean age 44.2 years, range 31-60 years), and their preoperative KPS scores were higher (mean 85, range 60-100). Four of the six patients underwent gross-total resection. In five patients (83.3%) the progression-free interval was longer than 5 years and in three a histopathological diagnosis of giant cell GBM was made. This diagnosis was not made in the other 107 patients. CONCLUSIONS: Among adult patients with supratentorial GBM, female sex and histopathological characteristics consistent with giant cell GBM may be predictive of a better survival rate, as may traditional factors (that is, younger age, good KPS score, more aggressive resection, and a long progression-free interval).

Constitutively active forms of c-Jun NH2-terminal kinase are expressed in primary glial tumors.

The c-Jun NH(2)-terminal kinases (JNKs) have a role both in promoting apoptosis and tumorigenesis. The JNKs are encoded by three separate genes (JNK1, 2, and 3), which are spliced alternatively to create 10 JNK isoforms that are either M(r) 55,000 or 46,000 in size. However, the functional significance and distinct role for each splice variant remains unclear. We have noted previously that 86% of primary human glial tumors show activation of almost exclusively the M(r) 55,000 isoforms of JNK. To further study which isoforms are involved, we constructed glutathione S-transferase fusion proteins for all 10 JNK isoforms and examined kinase activity with or without the activating upstream kinase. Surprisingly, five JNK isoforms demonstrate autophosphorylation activity, and in addition, all four JNK2 isoforms (either M(r) 55,000 or 46,000) show a high basal level of substrate kinase activity in the absence of the upstream kinase, especially a M(r) 55,000 JNK2 isoform. Examination revealed autophosphorylation activity at the T-P-Y motif, which is critical for JNK activation, because a mutant lacking the dual phosphorylation sites did not show autophosphorylation or basal kinase activity. Using green fluorescence protein-JNK expression vectors, transient transfection into U87MG cells demonstrates that although the JNK1 isoforms localize predominantly to the cytoplasm, the JNK2 isoforms localize to the nucleus and are phosphorylated, confirming the constitutive activation seen in vitro. We then examined which JNK isoforms are active in glial tumors by performing two-dimensional electrophoresis. This revealed that the M(r) 55,000 isoforms of JNK2 are the principal active JNK isoforms present in tumors. Collectively, these results suggest that these constitutively active JNK isoforms play a significant role in glial tumors. Aside from epidermal growth factor receptor vIII, this is the only other kinase that has been shown to be basally active in glioma. The presence of constitutively active JNK isoforms may have implications for the design of inhibitors of the JNK pathway.

Hyperploidy induced by drugs that inhibit formation of microtubule promotes chromosome instability.

BACKGROUND: Antimicrotubule drugs (AMDs), such as taxol and vincristine, are the most important addition to the chemotherapeutic armamentarium against human cancers. It has been shown that prolonged AMD treatment induces hyperploidy in G1-checkpoint-defective cancer cells and that these hyperploid cells subsequently undergo apoptosis. However, a fraction of these hyperploid cells are able to survive the prolonged mitotic stress and resume cell-cycle progression. RESULTS: We established hyperploid clones that escaped from cell death after AMD treatment from two glioma cell lines, U251MG and U87MG. Subtractive comparative genomic hybridization (CGH) analysis revealed that clones derived from U87MG mainly had chromosome number changes, but that those from U251MG showed both numerical and structural chromosomal changes. Furthermore, numerous aberrations identified in U251MG clones were remarkably chromosome-specific, which may have been due to clonal selection for cells that have an advantage in growth and/or survival. All clones derived from both cell lines had abnormalities in chromosome segregation, and karyotypes of clones were more heterogeneous than those of parental cells, suggesting that cells having a higher chromosome number are subject to asymmetric chromosome segregation, resulting in a heterogeneous karyotype. All clones derived from U87MG and U251MG increased both centric and acentromeric micronuclei, suggesting the presence of chromosome structural abnormality. CONCLUSIONS: AMD treatment induces hyperploid formation and chromosome instability in checkpoint-deficient cancer cells.

Proteolytic cleavage of the CD44 adhesion molecule in multiple human tumors.

Cell surface adhesion molecules are crucial for the development and/or pathogenesis of various diseases including cancer. CD44 has received much interest as a major adhesion molecule that is involved in tumor progression. We have previously demonstrated that the ectodomain of CD44 undergoes proteolytic cleavage by membrane-associated metalloproteases in various tumor cell lines. The remaining membrane-bound CD44 cleavage product can be detected using antibodies against the cytoplasmic domain of CD44 (anti-CD44cyto antibody). However, the cleavage of CD44 in primary human tumors has not been investigated. Using Western blots with anti-CD44cyto antibody to assay human tumor tissues, we show that the CD44 cleavage product can be detected in 58% (42 of 72) of gliomas but not in normal brain. Enhanced CD44 cleavage was also found in 67% (28 of 42) of breast carcinomas, 45% (5 of 11) of non-small cell lung carcinomas, 90% (9 of 10) of colon carcinomas, and 25% (3 of 12) of ovarian carcinomas. Tumors expressing a CD44 splice variant showed a significantly higher incidence of enhanced CD44 cleavage. The wide prevalence of CD44 cleavage suggests that it plays an important role in the pathogenesis of human tumors.