Intralesional TLR4 agonist treatment strengthens the organ defense against colonizing cancer cells in the brain.

Brain metastasis in breast cancer remains difficult to treat and its incidence is increasing. Therefore, the development of new therapies is of utmost clinical relevance. Recently, toll-like receptor (TLR) 4 was correlated with IL6 expression and poor prognosis in 1 215 breast cancer primaries. In contrast, we demonstrated that TLR4 stimulation reduces microglia-assisted breast cancer cell invasion. However, the expression, prognostic value, or therapeutic potential of TLR signaling in breast cancer brain metastasis have not been investigated. We thus tested the prognostic value of various TLRs in two brain-metastasis gene sets. Furthermore, we investigated different TLR agonists, as well as MyD88 and TRIF-deficient microenvironments in organotypic brain-slice ex vivo co-cultures and in vivo colonization experiments. These experiments underline the ambiguous roles of TLR4, its adapter MyD88, and the target nitric oxide (NO) during brain colonization. Moreover, analysis of the gene expression datasets of breast cancer brain metastasis patients revealed associations of TLR1 and IL6 with poor overall survival. Finally, our finding that a single LPS application at the onset of colonization shapes the later microglia/macrophage reaction at the macro-metastasis brain-parenchyma interface (MMPI) and reduces metastatic infiltration into the brain parenchyma may prove useful in immunotherapeutic considerations.

The Management of Brain Metastases-Systematic Review of Neurosurgical Aspects.

The multidisciplinary management of patients with brain metastases (BM) consists of surgical resection, different radiation treatment modalities, cytotoxic chemotherapy, and targeted molecular treatment. This review presents the current state of neurosurgical technology applied to achieve maximal resection with minimal morbidity as a treatment paradigm in patients with BM. In addition, we discuss the contribution of neurosurgical resection on functional outcome, advanced systemic treatment strategies, and enhanced understanding of the tumor biology.

Single-institution cross-sectional study to evaluate need for information and need for referral to psychooncology care in association with depression in brain tumor patients and their family caregivers.

BACKGROUND: The prognosis of patients with brain tumors is widely varying. Psychooncologic need and depression are high among these patients and their family caregivers. However, the need for counselling and need for referral to psychooncology care is often underestimated. METHODS: We performed a single-institution cross-sectional study to evaluate psychooncologic need, depression and information need in both patients and their family caregivers. The Hornheider Screening Instrument (HSI) and the Patient Health Questionnaire (PHQ-9) were used to evaluate psychooncologic need and depression, and a study-specific questionnaire was developed to evaluate information need. Multivariable analyses were performed to detect correlations. RESULTS: A total of 444 patients and their family caregivers were approached to participate, with a survey completion rate of 35.4%. More than half of the patients and family caregivers were in need for referral to psychooncology care and 31.9% of patients suffered from clinically relevant depression. In multivariable analysis, psychooncologic need were positively associated with mild (odds ratio, OR, 7.077; 95% confidence interval, CI, 2.263-22.137; p = 0.001) or moderate to severe (OR 149.27, 95% CI 26.690-737.20; p <  0.001) depression. Patient information need was associated with depression (OR 3.007, 95% CI 1.175-7.695; p = 0.022). CONCLUSIONS: Unmet counselling need in brain tumor patients and their family caregivers associate to high psychooncologic need and depression. Adequate information may decrease the need for referral to psychooncology care and treatment of depression in these patients. Future studies should further explore these relations to promote development of supportive structures.

LEF1 supports metastatic brain colonization by regulating glutathione metabolism and increasing ROS resistance in breast cancer.

More than half of all brain metastases show infiltrating rather than displacing growth at the macro-metastasis/organ parenchyma interface (MMPI), a finding associated with shorter survival. The lymphoid enhancer-binding factor-1 (LEF1) is an epithelial-mesenchymal transition (EMT) transcription factor that is commonly overexpressed in brain-colonizing cancer cells. Here, we overexpressed LEF1 in an in vivo breast cancer brain colonization model. It shortened survival, albeit without engaging EMT at the MMPI. By differential proteome analysis, we identified a novel function of LEF1 as a regulator of the glutathione (GSH) system, the principal cellular redox buffer. LEF1 overexpression also conferred resistance against therapeutic GSH depletion during brain colonization and improved management of intracellular ROS. We conclude that besides EMT, LEF1 facilitates metastasis by improving the antioxidative capacity of epithelial breast cancer cells, in particular during colonization of the brain parenchyma.

A Patient-Independent Significance Test by Means of False-Positive Rates in Selected Correlation Analysis of Brain Multimodal Monitoring Data.

Recently, we introduced a mathematical toolkit called selected correlation analysis (sca) that reliably detects negative and positive correlations between arterial blood pressure (ABP) and intracranial pressure (ICP) data, recorded during multimodal monitoring, in a time-resolved way. As has been shown with the aid of a mathematical model of cerebral perfusion, such correlations reflect impaired autoregulation and reduced intracranial compliance in patients with critical neurological diseases. Sca calculates a Fourier transform-based index called selected correlation (sc) that reflects the strength of correlation between the input data and simultaneously an index called mean Hilbert phase difference (mhpd) that reflects the phasing between the data. To reliably detect pathophysiological conditions during multimodal monitoring, some thresholds for the abovementioned indexes sc and mhpd have to be established that assign predefined significance levels to that thresholds. In this paper, we will present a method that determines the rate of false positives for fixed pairs of thresholds (lsc, lmhpd). We calculate these error rates as a function of the predefined thresholds for each individual out of a patient cohort of 52 patients in a retrospective way. Based on the deviation of the individual error rates, we subsequently determine a globally valid upper limit of the error rate by calculating the predictive interval. From this predictive interval, we deduce a globally valid significance level for appropriate pairs of thresholds that allows the application of sca to every future patient in a prospective, bedside fashion.

Efficacy of D,L-methadone in the treatment of glioblastoma in vitro.

AIM: Recently, D,L-methadone has been put forward as adjuvant treatment in glioblastoma (GBM). METHODS: We analyzed the µ-opioid receptor expression in a set of GBM cell lines and investigated the efficacy of D,L-methadone alone and in combination with temozolomide (TMZ). Results & conclusion: Expression of the µ-opioid receptor was similar in the tested cell lines. High concentrations of D,L-methadone induced apoptosis in all cell lines and showed treatment interaction with TMZ. However, in lower dosages, reflecting clinically attainable concentrations, D,L-methadone alone showed no efficacy, and induced even higher proliferation in one specific cell line. Also, no interaction with TMZ was observed. These results suggest caution to the premature use of D,L-methadone in the treatment of GBM patients.

Detection of Impaired Cerebral Autoregulation Using Selected Correlation Analysis: A Validation Study.

Multimodal brain monitoring has been utilized to optimize treatment of patients with critical neurological diseases. However, the amount of data requires an integrative tool set to unmask pathological events in a timely fashion. Recently we have introduced a mathematical model allowing the simulation of pathophysiological conditions such as reduced intracranial compliance and impaired autoregulation. Utilizing a mathematical tool set called selected correlation analysis (sca), correlation patterns, which indicate impaired autoregulation, can be detected in patient data sets (scp). In this study we compared the results of the sca with the pressure reactivity index (PRx), an established marker for impaired autoregulation. Mean PRx values were significantly higher in time segments identified as scp compared to segments showing no selected correlations (nsc). The sca based approach predicted cerebral autoregulation failure with a sensitivity of 78.8% and a specificity of 62.6%. Autoregulation failure, as detected by the results of both analysis methods, was significantly correlated with poor outcome. Sca of brain monitoring data detects impaired autoregulation with high sensitivity and sufficient specificity. Since the sca approach allows the simultaneous detection of both major pathological conditions, disturbed autoregulation and reduced compliance, it may become a useful analysis tool for brain multimodal monitoring data.

Extent of Resection in Newly Diagnosed Glioblastoma: Impact of a Specialized Neuro-Oncology Care Center.

Treatment of glioblastoma (GBM) consists of microsurgical resection followed by concomitant radiochemotherapy and adjuvant chemotherapy. The best outcome regarding progression free (PFS) and overall survival (OS) is achieved by maximal resection. The foundation of a specialized neuro-oncology care center (NOC) has enabled the implementation of a large technical portfolio including functional imaging, awake craniotomy, PET scanning, fluorescence-guided resection, and integrated postsurgical therapy. This study analyzed whether the technically improved neurosurgical treatment structure yields a higher rate of complete resection, thus ultimately improving patient outcome. PATIENTS AND METHODS: The study included 149 patients treated surgically for newly diagnosed GBM. The neurological performance score (NPS) and the Karnofsky performance score (KPS) were measured before and after resection. The extent of resection (EOR) was volumetrically quantified. Patients were stratified into two subcohorts: treated before (A) and after (B) the foundation of the Regensburg NOC. The EOR and the PFS and OS were evaluated. RESULTS: Prognostic factors for PFS and OS were age, preoperative KPS, O6-methylguanine-DNA-methyltransferase (MGMT) promoter methylation status, isocitrate dehydrogenase 1 (IDH1) mutation status and EOR. Patients with volumetrically defined complete resection had significantly better PFS (9.4 vs. 7.8 months; p = 0.042) and OS (18.4 vs. 14.5 months; p = 0.005) than patients with incomplete resection. The frequency of transient or permanent postoperative neurological deficits was not higher after complete resection in both subcohorts. The frequency of complete resection was significantly higher in subcohort B than in subcohort A (68.2% vs. 34.8%; p = 0.007). Accordingly, subcohort B showed significantly longer PFS (8.6 vs. 7.5 months; p = 0.010) and OS (18.7 vs. 12.4 months; p = 0.001). Multivariate Cox regression analysis showed complete resection, age, preoperative KPS, and MGMT promoter status as independent prognostic factors for PFS and OS. Our data show a higher frequency of complete resection in patients with GBM after the establishment of a series of technical developments that resulted in significantly better PFS and OS without increasing surgery-related morbidity.

Parameter Optimization for Selected Correlation Analysis of Intracranial Pathophysiology.

Recently we proposed a mathematical tool set, called selected correlation analysis, that reliably detects positive and negative correlations between arterial blood pressure (ABP) and intracranial pressure (ICP). Such correlations are associated with severe impairment of the cerebral autoregulation and intracranial compliance, as predicted by a mathematical model. The time resolved selected correlation analysis is based on a windowing technique combined with Fourier-based coherence calculations and therefore depends on several parameters. For real time application of this method at an ICU it is inevitable to adjust this mathematical tool for high sensitivity and distinct reliability. In this study, we will introduce a method to optimize the parameters of the selected correlation analysis by correlating an index, called selected correlation positive (SCP), with the outcome of the patients represented by the Glasgow Outcome Scale (GOS). For that purpose, the data of twenty-five patients were used to calculate the SCP value for each patient and multitude of feasible parameter sets of the selected correlation analysis. It could be shown that an optimized set of parameters is able to improve the sensitivity of the method by a factor greater than four in comparison to our first analyses.

Continuous intra-arterial nimodipine infusion in patients with severe refractory cerebral vasospasm after aneurysmal subarachnoid hemorrhage: a feasibility study and outcome results.

BACKGROUND: Severe cerebral vasospasm is a major cause of death and disability in patients with aneurysmal subarachnoid hemorrhage. No causative treatment is yet available and hypertensive hypervolemic therapy (HHT) is often insufficient to avoid delayed cerebral ischemia and neurological deficits. We compared patients receiving continuous intra-arterial infusion of the calcium-antagonist nimodipine with a historical group treated with HHT and oral nimodipine alone. METHODS: Between 0.5 and 1.2 mg/h of nimodipine were continuously administered by intra-arterial infusion via microcatheters either into the internal carotid or vertebral artery or both, depending on the areas of vasospasm. The effect was controlled via multimodal neuromonitoring and transcranial Doppler sonography. Outcome was determined by means of the Glasgow Outcome Scale at discharge and 6 months after the hemorrhage and compared to a historical control group. RESULTS: Twenty-one patients received 28 intra-arterial nimodipine infusions. Six months after discharge, the occurrence of cerebral infarctions was significantly lower (42.6 %) in the nimodipine group than in the control group (75.0 %). This result was reflected by a significantly higher proportion (76.0 %) of patients with good outcome in the nimodipine-treated group, when compared to 10.0 % good outcome in the control group. Median GOS was 4 in the nimodipine group and 2 in the control group (p = 0.001). CONCLUSIONS: Continuous intra-arterial nimodipine infusion is an effective treatment for patients with severe cerebral vasospasm who fail to respond to HHT and oral nimodipine alone. Key to the effective administration of continuous intra-arterial nimodipine is multimodal neuromonitoring and the individual adaptation of dosage and time of infusion for each patient.

TGF-ß isoforms in cancer: Immunohistochemical expression and Smad-pathway-activity-analysis in thirteen major tumor types with a critical appraisal of antibody specificity and immunohistochemistry assay validity.

The literature on TGF-ß in cancer including data on the expression or activation of TGF-ß pathway components in specific tumors types is steadily growing. However, no systematic and uniform analysis exists reporting expression levels of the main TGF-ß pathway components across the most frequent tumor types. We used a standardized immunohistochemical assay investigating TGF-ß isoform expression and pathway activation across 13 different tumor types and corresponding non-neoplastic tissues. The study was performed on tissue microarrays allowing for the parallel analysis of a total of 1638 human tumor samples. TGF-ß1, TGF-ß2 and p-Smad2/3 were substantially expressed in multiple cancers widening the options for TGF-ß isoform directed therapies. Of note, TGF-ß antigens appear to be expressed in an individual manner pointing towards a need for patient preselection for TGF-ß isoform specific treatment. Yet, a thorough investigation of antibody specificity and assay validity revealed that immunohistochemistry did not correlate with other detection methods on mRNA or protein level in all instances. As such, with the currently available means (i.e. antibodies tested) a stratification of patients within clinical trials for TGF-ß directed antisense therapies based upon TGF-ß immunohistochemistry alone has to be interpreted with caution and should be carefully evaluated in combination with other parameters.

Systematic investigation of CMTM family genes suggests relevance to glioblastoma pathogenesis and CMTM1 and CMTM3 as priority targets.

The novel CKLF-like Marvel Transmembrane Domain-containing gene family (CMTM) consists of 8 members (CMTM1-8). As little is known about the oncogenic impact of these genes, we aimed to systematically investigate the relevance of CMTMs to glioblastoma pathogenesis. We performed mRNA expression analyses and survival correlations in glioblastoma patients. Moreover, we analyzed the impact of RNAi-based silencing and overexpression of CMTM family genes on tumor cell proliferation and invasion in vitro. CMTMs appeared to be widely regulated in the group of glioblastomas relative to non-neoplastic brain (NB) tissue (significant upregulation for CMTM2, 3, and 6 and significant downregulation for CMTM 4 and 8). For CMTM1, 5 and 7, we found aberrant expression levels in individual tumors. Functionally, CMTM1, 3, and 7 promoted tumor cell invasion, while CMTM1 additionally enhanced cell proliferation. In a large clinically annotated dataset, higher CMTM1 and 3 expression was significantly correlated with shorter overall survival. Our data thus suggest CMTM1 and 3 as priority targets in glioblastomas. Using a human phosphokinase protein expression profiling assay, we can provide first insights into signalling of these two genes that might be conveyed by growth factor receptor, Src family kinase and WNT activation.

Windowed multitaper correlation analysis of multimodal brain monitoring parameters.

Although multimodal monitoring sets the standard in daily practice of neurocritical care, problem-oriented analysis tools to interpret the huge amount of data are lacking. Recently a mathematical model was presented that simulates the cerebral perfusion and oxygen supply in case of a severe head trauma, predicting the appearance of distinct correlations between arterial blood pressure and intracranial pressure. In this study we present a set of mathematical tools that reliably detect the predicted correlations in data recorded at a neurocritical care unit. The time resolved correlations will be identified by a windowing technique combined with Fourier-based coherence calculations. The phasing of the data is detected by means of Hilbert phase difference within the above mentioned windows. A statistical testing method is introduced that allows tuning the parameters of the windowing method in such a way that a predefined accuracy is reached. With this method the data of fifteen patients were examined in which we found the predicted correlation in each patient. Additionally it could be shown that the occurrence of a distinct correlation parameter, called scp, represents a predictive value of high quality for the patients outcome.

Skull base meningiomas: neurological outcome after microsurgical resection.

Microsurgical resection is the primary treatment of skull base meningiomas. Maximal resection provides the best tumor control rates but can be associated with high surgical morbidity. To understand the relation between extent of resection (EOR) and functional outcome we have analyzed the neurological improvement and recurrence rate in a large consecutive series of skull base meningioma patients. In addition, we defined anatomical and biological factors predictive for recurrence and overall outcome. We investigated 226 skull base meningioma patients receiving tumor resection in our institution. The most frequent location was the medial sphenoid ridge (29.6 %). EOR was rated according to the Simpson scale. Overall performance was measured by the Karnofsky performance score (KPS); neurological deficits were quantified using the Medical Research Council Neurological Severity Score (MRC-NPS). Complete resection was achieved in 62.8 % and the EOR was significantly correlated to tumor location. The morbidity and mortality rate was 32.1 and 2.7 % respectively, new permanent neurological deficits occurred in 3.5 % of all patients. From all patients with focal neurological deficits, 60.1 % experienced significant improvement. Both the MRC-NPS and the KPS significantly improved from the preoperative status to discharge, however the improvement rate was dependent on the tumor location. Recurrence rate was 15.5 %; tumor size, bone- and venous sinus infiltration, WHO grade, poor EOR but not MIB-1 labeling index were independent factors predictive for recurrence. Microsurgical resection of skull base meningiomas improves neurological impairment in the majority of patients. Specific risk factors for recurrence require consideration for postoperative management.

Function of carbonic anhydrase IX in glioblastoma multiforme.

Carbonic anhydrase (CA) IX is over-expressed in glioblastoma; however, its functions in this context are unknown. Metabolically, glioblastomas are highly glycolytic, leading to a significant lactic acid load. Paradoxically, the intracellular pH is alkaline. We hypothesized that CAIX contributes to the extrusion of hydrogen ions into the extracellular space, thereby moderating intra- and extracellular pH and creating an environment conductive to enhanced invasion. We investigated the role of CAIX as a prognostic marker in patients with glioblastoma and its biological function in vitro. CAIX expression was analyzed in 59 patients with glioblastoma by immunohistochemistry. The expression levels were correlated to overall survival. In vitro, U251 and Ln 18 glioblastoma cells were incubated under hypoxia to induce CAIX expression, and RNA interference (RNAi) was used to examine the function of CAIX on cell attachment, invasion, intracellular energy transfer, and susceptibility to adjuvant treatment. High CAIX expression was identified as an independent factor for poor survival in patients with glioblastoma. In vitro, cell attachment and invasion were strongly reduced after knockdown of CAIX. Finally, the effects of radiation and chemotherapy were strongly augmented after CAIX interference and were accompanied by a higher rate of apoptotic cell death. CAIX is an independent prognostic factor for poor outcome in patients with glioblastoma. Cell attachment, invasion, and survival during adjuvant treatment are significantly influenced by high CAIX expression. These results indicate that inhibition of CAIX is a potential metabolic target for the treatment of patients with glioblastoma.

Computerized data analysis of neuromonitoring parameters identifies patients with reduced cerebral compliance as seen on CT.

OBJECTIVE: Computer-assisted analysis of neuromonitoring parameters may provide important decision-making support to the neurointensivist. A recently developed mathematical model for the simulation of cerebral autoregulation and brain swelling showed that in the case of an intact autoregulation but diminished cerebral compliance, a negative correlation between arterial blood pressure (ABP) and intracranial pressure (ICP) occurs. The goal of our study was to verify these simulation results in an appropriate patient cohort. METHODS: Simultaneously measured data (ABP, ICP) of 6 patients (1 female; 5 male) with severe head trauma (n = 5) and stroke (n = 1) were used to calculate time resolved multitaper cross coherence. Further, we calculated the Hilbert phases of both signals, defining a negative correlation in case of a mean Hilbert phase difference greater than 130°. To validate the results, CT scans performed during the critical phases identified were analyzed. RESULTS: In five out of six datasets we found long lasting events of negative correlation between ABP and ICP. In all patients, corresponding CT scans demonstrated changes in the intracranial compartment characterized by diminished cerebral compliance. CONCLUSIONS: Our data indicate that complex multidimensional data analysis of neuromonitoring parameters can identify complication-specific data patterns with a high degree of accuracy.

Recurrent brain metastases from lung cancer: the impact of reoperation.

OBJECTIVE: The best treatment for solitary brain metastases from lung cancer is surgical resection followed by adjuvant treatment. However, about 50% of these patients develop recurrent brain metastases. There is no established treatment standard for this patient group. We therefore analyzed the survival, neurological function, and overall performance status of patients with recurrent solitary brain metastases from lung cancer after second microsurgical resection. MATERIALS AND METHODS: Treatment outcome was analyzed in 25 patients (19 men, 6 women) with a mean age of 55.8 years (range, 38-78 years) who received a resection of recurrent solitary brain metastases. Eighty-four percent of all patients had non-small-cell lung cancer and 16% small cell lung cancer (SCLC). Eighty percent of the lesions were located supratentorially, 20% infratentorially. RESULTS: The median overall survival after initial diagnosis was 26.9 months, 13.6 months after the first and 8.3 months after the second brain surgery, respectively. The median Karnofsky index improved significantly from 80 to 100 after the second brain surgery; 66.6% of all patients presenting with neurological impairment improved, and 50% regained normal function. No surgery-related morbidity or mortality was noted. Multivariate analysis indicated that the interval until first brain metastasis and between first and recurrent metastases was significantly predictive of survival. CONCLUSIONS: The majority of patients in our study group showed significant functional benefit from surgical resection of recurrent brain metastases. This contributes to a better quality of life in this patient group showing a short overall survival time.

Growth pattern analysis of sphenoid wing meningiomas.

PURPOSE: Complete resection is crucial for the management of sphenoid wing meningiomas (SWM). We hypothesized that specific anatomical growth patterns are predictive for recurrence and worse prognosis. We therefore analyzed the extension patterns of SWM and correlated them with intraoperative findings, extent of resection and recurrence rate. METHODS: MRI and CT scans were utilized to analyze soft tissue and bone extension, respectively. Soft tissue extension was quantified using four, bone infiltration using eight anatomical landmarks. The extent of resection was graded according to the Simpson classification (grade I-V). Finally,the growth pattern analysis was correlated with recurrence rate. RESULTS: We included 44 patients, 37 female (84.1%) and 7 male (15.9%). Tumor recurrence was observed in 13 patients (29.5%). Patients with recurrent tumors had a significantly worse Simpson score (p=0.01). Soft tissue spread into the cavernous sinus and bony infiltration of the superior orbital fissure was associated with a poor Simpson grade (p=0.001). Bony infiltration of the orbital roof superior orbital fissure was highly predictive for tumor recurrence (p=0.002). CONCLUSIONS: Structured radiological and anatomical analysis of the SWM growth pattern may influence the surgical strategy and facilitate the management and prognostication of patients with SWM.

Regulation and function of aquaporin-1 in glioma cells.

Glioblastoma multiformes (GBMs) express increased aquaporin (AQP) 1 compared to normal brain. AQPs may contribute to edema, cell motility, and shuttling of H(2)O and H(+) from intracellular to extracellular space. We sought to gain insight into AQP1 function in GBM. In cultured 9L gliosarcoma cells, AQP1 expression was induced by dexamethasone, platelet-derived growth factor, NaCl, hypoxia, D-glucose (but not L-glucose), and fructose. Induction of AQP1 expression correlated with the level of glycolysis, maximized by increasing medium D-glucose or fructose and decreasing O(2), and was quantified by measuring lactate dehydrogenase (LDH) activity and medium lactate concentration. Upregulation of the protease cathepsin B was also observed in 9L cells cultured under glycolytic conditions. Immunohistochemical staining of human GBM specimens revealed increased coincident expression of AQP1, LDH, and cathepsin B in glioma cells associated with blood vessels at the tumor periphery. GBMs are known to exhibit aerobic glycolysis. Increased glucose metabolism at the tumor periphery may provide a scenario by which upregulation of AQP1, LDH, and cathepsin B contributes to acidification of the extracellular milieu and to invasive potential of glioma cells in perivascular space. The specific upregulation and metabolic consequences of increased AQP1 in gliomas may provide a therapeutic target, both as a cell surface marker and as a functional intervention.

Comparative proteomic profiles of meningioma subtypes.

Meningiomas are classified into three groups (benign, atypical, and anaplastic) based on morphologic characteristics. Atypical meningiomas, which are WHO grade 2 tumors, and anaplastic meningiomas, which are WHO grade 3 tumors, exhibit an increased risk of recurrence and premature death compared with benign WHO grade 1 tumors. Although atypical and anaplastic meningiomas account for <10% of all of meningiomas, it can be difficult to distinguish them from benign meningiomas by morphologic criteria alone. We used selective tissue microdissection to examine 24 human meningiomas and did two-dimensional gel electrophoresis to determine protein expression patterns. Proteins expressed differentially by meningiomas of each WHO grade were identified and sequenced. Proteomic analysis revealed protein expression patterns unique to WHO grade 1, 2, and 3 meningiomas and identified 24 proteins that distinguish each subtype. Fifteen proteins showed significant changes in expression level between benign and atypical meningiomas, whereas nine distinguished atypical from anaplastic meningiomas. Differential protein expression was confirmed by Western blotting and immunohistochemistry. We established differential proteomic profiles that characterize and distinguish meningiomas of increasing grades. The proteins and proteomic profiles enhance understanding of the pathogenesis of meningiomas and have implications for diagnosis, prognosis, and treatment.