Sam-Suk Kang

The correlation and prognostic significance of MGMT promoter methylation and MGMT protein in glioblastomas.

OBJECTIVEThe aim of this study was to evaluate the correlation and prognostic significance of MGMT promoter methylation and protein expression in patients with glioblastoma. METHODSEighty-three patients with glioblastoma underwent surgery followed by radiotherapy and temozolomide chemotherapy between October 2000 and June 2008. To investigate the correlation between MGMT methylation and MGMT expression, methylation-specific polymerase chain reaction (MSP) and immunohistochemical staining was performed. To analyze the correlation between MGMT methylation and MGMT expression according to location, biopsies were obtained from 37 different sites within the tumors in 12 patients. Age, sex, Karnofsky Performance Scale status, extent of removal, chemotherapeutic methods, and MGMT promoter methylation and protein expression were analyzed as prognostic factors. RESULTSThe total median survival was 15.8 months (range, 12.6–19.1 months). The results of MSP were the same at various sites in 12 patients. A correlation between MSP and immunohistochemical staining was observed in 50% of the patients. In 73 patients, negative MGMT expression was detected in 70.5% of 44 patients with MGMT promoter methylation, and positive expression was observed in 55.2% of the 29 patients with unmethylated promoters. Multivariate analysis revealed that the extent of removal (P = 0.001) and the combination of MGMT promoter methylation and negative MGMT expression (median survival, 20.06 months; P = 0.006) were significantly associated with longer survival. CONCLUSIONWe report the feasibility of using MSP combined with immunohistochemical staining as a prognostic factor. The results of the present study suggest that MGMT promoter methylation in combination with negative MGMT expression might be a good prognostic factor in patients with glioblastoma.

Preparation of poly(dl-lactide-co-glycolide) microspheres encapsulating all-trans retinoic acid

Poly(DL-lactide-co-glycolide) (PLGA) microspheres containing all-trans retinoic acid (atRA) were prepared by o/w solvent evaporation method and various preparation parameters, such as poly(vinyl alcohol) (PVA) concentration in aqueous solution, PVA MW, drug weight, solvent, polymer MW, and polymer weight, on the characteristics of microspheres and drug release were investigated. PVA concentration in water phase was a critical factor in making microspheres consistently with smooth surface and round shape. In our study, at least 2% (w/v) of PVA in aqueous solution was necessary for making microspheres with round shape. The particle size of microspheres ranged 10-100 microm. AtRA was slowly released from PLGA microspheres over 30 days. Sterilization of microspheres by ethylene oxide (EO) gas at 37 degrees C did not significantly affect the characteristics of drug release or its morphology. Cell growth inhibition of atRA was affected by preparation process of microspheres rather than the EO-gas sterilization process. These results indicate that PLGA microspheres containing atRA are acceptable for controlled release devices for use in the treatment of brain tumor.

Current surgical results of retrosigmoid approach in extralarge vestibular schwannomas

BACKGROUNDnVestibular schwannomas (VS) are common tumors that can be cured; they are reported to comprise 6 approximately 8% of all intracranial tumors. The primary objective in the surgery of extralarge VS is total removal of the tumor mass while preserving the facial nerve. In extralarge tumors, complete excision of the tumor carries a significant risk of injuring the facial nerve and adjacent vital brain structures. The authors are reporting the techniques and results of operation on extralarge VS.nnnMETHODSnThe material consisted of 30 patients during the last 6 years with surgically treated VS that had a maximal extrameatal diameter exceeding 4 cm. Suboccipital craniotomy and tumor removal was performed with patients in the lateral position. Results and complications of the surgical technique will be reviewed.nnnRESULTSnAverage age of patients was 45.2 years; there was a slight female predominance (1.5:1). Size of the mass ranged from 41 to 70 mm; all were removed by the retrosigmoid transmeatal approach. Peritumoral edema on MRI was seen in 50% (15/30). Total removal was achieved in 73.3% (22/30) with no significant relationship to peritumoral edema. In the cases of total removal, the facial nerve preservation rate was 86.4% (19/22). There was no mortality. Surgical complications were hemorrhage and CSF leakage in 1 case (3%) and 8 cases (26.7%), respectively, but in most of these cases, conservative treatment was adequate. In patients in whom anatomic preservation of the facial nerve was achieved, facial nerve function improved progressively within a year. In all cases except for one with gait disturbance, a good outcome was achieved.nnnCONCLUSIONSnOur surgical techniques, including the prediction of facial nerve displacement, not using retractors, and replacement of bone, contributed to good surgical results in a series of extralarge VS.

Role of galectin-1 in migration and invasion of human glioblastoma multiforme cell lines

OBJECTnGalectin-1 is highly expressed in motile cell lines. The authors investigated whether galectin-1 actually modulates the migration and invasion of human glioblastoma multiforme (GBM) cell lines, and whether its expression with respect to invasion and prognosis is attributable to certain glioma subgroups.nnnMETHODSnIn the human GBM cell lines U343MG-A, U87MG, and U87MG-10, the RNA differential display was evaluated using Genefishing technology. The results were validated by reverse transcription polymerase chain reaction and Northern blot analysis to detect possible genetic changes as the determining factors for the motility of the malignant glioma. The migration and invasion abilities were investigated in human GBM cell lines and galectin-1 transfectant using an in vitro brain slice invasion model and a simple scratch technique. The morphological and cytoskeletal (such as the development of actin and vimentin) changes were examined under light and confocal microscopy. Galectin-1 expression was assessed on immunohistochemical tests and Western blot analysis.nnnRESULTSnEndogenous galectin-1 expression in the human GBM cell lines was statistically correlated with migratory abilities and invasiveness. The U87-G-AS cells became more round than the U87MG cells and lacked lamellipodia. On immunohistochemical staining, galectin-1 expression was increased in higher-grade glioma subgroups (p = 0.027).nnnCONCLUSIONSnDiffuse gliomas demonstrated higher expression levels than pilocytic astrocytoma in the Western blot. Galectin-1 appears to modulate migration and invasion in human glioma cell lines and may play a role in tumor progression and invasiveness in human gliomas.

Brain tumor invasion model system using organotypic brain-slice culture as an alternative to in vivo model

Abstractn Purpose. The primary cause of local recurrence and therapeutic failure in the treatment of malignant gliomas is the invasion of tumor cells into the surrounding normal brain. While it is known that malignant gliomas infiltrate diffusely into regions of normal brain, it is frequently very difficult to unequivocally identify the solitary invading glioma cell in histopathological preparations, or in experimental glioma models. We have developed an experimental invasion assay system, which allows us to track the solitary invasive glioma cell, using human brain tissue obtained from routine craniotomies for seizures or trauma.n Methods. This tissue is cut into 1-mm thick slices and cultured in the upper chamber of Transwell culture dishes on top of a 0.4-µm pore size polyester membrane, which is fed on medium provided in the lower chamber. Glioma cells are stably transfected with vectors containing a green fluorescent protein (GFP) cDNA. Stable, high-level expression GFP transfectants were selected by direct visualization under fluorescence microscope. In addition, various tumor spheroids are stained with vital dye, DiI, to track the invading cells. GFP-expressing glioma cells or stained spheroids were then implanted on the center of the brain slice, and the degree of brain tumor invasion into the brain tissue was evaluated at different time points by optical sectioning using a confocal microscope.n Results. We observed that GFP-expressing glioma cells or stained spheroids could be readily tracked and followed with this model system. Individual tumor cells that exhibited green or red fluorescence could be identified and their migration path through the brain slices unequivocally followed.n Conclusion. This experimental invasion system may be of considerable utility in studying the process of brain tumor invasion and in evaluating its invasiveness in individual brain tumor because it not only provides a better representation of extracellular matrix molecules normally encountered by invading glioma cells, but also provides the fluorescent tag applied to the tumor cells.

Prognostic factors of postoperative visual outcomes in tuberculum sellae meningioma

Tuberculum sellae meningiomas usually present optic pathway related symptoms, such as decreased visual acuity and/or visual field defect. In this report, the authors retrospectively analysed 27 patients with tuberculum sellae meningioma who underwent surgical treatment and then sought to identify prognostic factors of the postoperative visual outcomes. From April 1998 to June 2006, the authors treated 27 patients diagnosed with tuberculum sellae meningioma. Age, gender, duration of symptoms, tumour size, tumour consistency on intraoperative and T2WI findings, and resectability were analysed as potential prognostic factors of postoperative visual outcomes. Pre- and postoperative ophthalmological examinations were performed in all patients. Of the 27 patients who presented with visual dysfunction before operation, 12 were improved (44.4%), nine were unchanged (33.3%) and six worsened (22.2%). Those patients with a symptom duration of less than 1 year had a greater likelihood of visual improvement than those with a symptom duration of more than 1 year and those with a soft tumour had a greater likelihood of visual improvement than those with a hard tumour, though this was without statistical significance. Moreover, patients with high signal intensity lesion on T2-weighted images had a greater likelihood of visual improvement than those with an iso or low signal intensity with statistical significance. An excellent correlation was found between tumour consistency and appearance on T2-weighted images (p = 0.001). The results of this study indicate that MRI-T2WI can be used to estimate tumour hardness preoperatively and that this is an important prognostic factor of the visual impairments caused by intrasellar meningioma.

Possible Pathophysiological Role of Vascular Endothelial Growth Factor (VEGF) and Matrix Metalloproteinases (MMPs) in Metastatic Brain Tumor-associated Intracerebral Hemorrhage

SummaryBackgroundIntratumoral hemorrhage, as one of the cerebrovascular complications in various tumor-related conditions, occurs mainly in malignant brain tumors. Recent studies have shown that the overexpression of vascular endothelial growth factor (VEGF) and metalloproteinase (MMP) may play a role for the loss of vascular integrity and the subsequent hemorrhage in several instances, in addition to their well-known properties in tumor development and metastasis.MethodsTo investigate the potential role of VEGF and MMP in hemorrhagic complication of metastatic brain tumor, we estimated the expression of VEGF, MMP-2 & -9 by immunohistochemical studies in pathological specimens of metastatic brain tumors obtained from 16 patients, 7 in hemorrhagic and 9 in non-hemorrhagic group. We also examined the expression of collagen type IV, CD34, Factor VIII in order to evaluate the status of tumor vasculature.ResultsPatients in hemorrhagic group showed a higher VEGF expression with neovascularization than those in non-hemorrhagic group. The basement membranes of newly formed vessels were disrupted in cases with high expression in both MMP-2 and -9. These results indicate that rapid growing nascent blood vessels, responding vigorously to VEGF, are concentrated around the hemorrhagic tumors. Besides, these results suggest a possibility that the basement membranes of these nascent vessels could be disrupted proteolytically by MMP.ConclusionWe conclude that overexpression of VEGF and MMP may play a role in metastatic brain tumor-associated hemorrhage. Presumably, the underlying pathophysiological mechanisms are through rapid growth and breakdown of vessels around the tumors caused by overexpression of VEGF and MMP of tumor cells.

Adult craniopharyngiomas: surgical results with a special focus on endocrinological outcomes and recurrence according to pituitary stalk preservation

OBJECTnThe aim of this study was to evaluate the results of surgical treatment of adult craniopharyngioma with a special focus on the endocrinological outcomes and tumor recurrence in cases of pituitary preservation.nnnMETHODSnBetween 1993 and February 2008, 41 patients underwent 47 surgical procedures for craniopharyngioma. The male/female ratio was 26:15 and the median age was 45.8 years (range 17-65 years). The median follow-up period was 10.56 years (range 6.2-14.9 years). Patients presented with visual disturbance before 30 (63.8%) of 47 procedures and with endocrinological disturbance before 12 (26%) procedures. Surgery was performed via a subfrontal/pterional approach in 31 procedures (66%), bifrontal interhemispheric in 6 (12.8%), transcallosal/transventricular in 5 (10.6%), combined in 1 (2.1%), and transsphenoidal in 4 (8.5%). The tumor was totally removed in 36 procedures (76.6%), subtotally in 10 (21.3%), and partially in 1 (2.1%).nnnRESULTSnPostoperatively, the rates of visual improvement and aggravation were 50 and 33.3%, respectively. Of 24 patients in whom the pituitary stalk was preserved, complete hormone replacement was needed in 14 (58.3%), partial replacement in 2 (8.3%), and no replacement in 8 (33.3%). The rate of tumor recurrence was 24.4%. The recurrence-free survival rate was significantly different between patients in whom complete tumor resection was accomplished and those in whom tumor resection was incomplete. Stalk preservation did not affect the recurrence-free survival rate. The morbidity and mortality rates were 8.5 and 2.1%, respectively.nnnCONCLUSIONSnThe pituitary stalk must be preserved with maximal tumor resection whenever possible to increase the chance of intact anterior pituitary function being maintained. The results of the present study show that pituitary stalk preservation may not be related to increased recurrence rates.

Primary central nervous system lymphoma presenting as an acute massive intracerebral hemorrhage: case report with immunohistochemical study

BACKGROUNDnHemorrhage at presentation in primary CNS lymphoma is extremely rare and only 2 studies have reported it. We experienced a case of hemorrhage in primary CNS lymphoma, but the feature was different from those in the 2 studies mentioned. We report a case of primary CNS lymphoma presenting as an acute massive ICH causing catastrophic mental deterioration, along with immunohistochemical profiles.nnnCASE DESCRIPTIONnA 49-year-old woman was admitted with sudden deterioration of mental status. Immediate CT scan showed a massive ICH in the left frontal lobe with perilesional edema and midline shifting. Emergency operation was performed and the hematoma was removed gross totally, including the abnormal lesions distinguished from adjacent normal brain. The histopathologic diagnosis was non-Hodgkin lymphoma, diffuse, large, B cell type with acute hemorrhage, and immunohistochemistry results showed high VEGF immunoreactivity and intermediate CD34 immunoreactivity.nnnCONCLUSIONnPrimary CNS lymphoma can present as an acute massive ICH, and immunohistochemistry in the present study strengthened the suggestion that VEGF activity is related to the hemorrhage in primary CNS lymphoma.

Clinical and histopathological analysis of cystic meningiomas

Between 1993 and 2003, we treated 21 patients with cystic meningioma (of 365 with meningioma, 5.5%). We grouped these patients according to classifications by Nauta and Rengachary and analyzed them by gender, age, tumor location, clinical manifestations, MRI features and histopathology. The mean duration of symptoms was relatively short at 1.6 months. There were five atypical and 16 benign meningiomas on histopathology. In type I and II cystic meningiomas, with intratumoral cysts, all cyst walls enhanced on MRI and had tumor cells in the cyst wall on histopathology. In type III and IV cystic meningiomas, with peritumoral cysts, the cyst wall did not enhance on MRI and only one case (type III) had tumor cells in the cyst wall on histopathology. We suggest that when the cyst wall shows contrast enhancement on imaging, the cyst wall should be completely removed at surgery. If there is no contrast enhancement, multiple biopsies of the cyst wall should be taken to assess the presence of tumor cells in the cyst wall.