YAP, TAZ and AREG expression in eighth cranial nerve schwannoma.

BACKGROUND: Although the diagnosis and treatment of eighth cranial nerve (VIII CN) schwannoma (acoustic neuroma) has improved over the years, no factors capable of predicting tumor growth have been identified as yet. This study is a preliminary investigation of the expression in sporadic VIII CN schwannomas of Yes-associated protein (YAP), transcriptional coactivator with PDZ-binding motif (TAZ), and amphiregulin (AREG), a direct target gene of YAP and TAZ. The expression of YAP, TAZ and AREG was correlated with the volumetric dimensions of tumors on contrast-enhanced magnetic resonance imaging (ceMRI). METHODS: YAP, TAZ and AREG expression was assessed immunohistochemically in surgical specimens of 36 consecutive sporadic VIII CN schwannomas. 3D reconstructions of the tumors and their corresponding volumes in cm3 were obtained from measurements on ceMRI images using the OsiriX® software. RESULTS: We found a significant direct correlation between TAZ expression and VIII CN schwannoma volumes on latest preoperative ceMRI (p<0.0003). Mean TAZ expression was also significantly higher in VIII CN schwannomas with a volume ≥2.1 cm3 than in those with a volume <2.1 cm3(p<0.0018). No significant correlations emerged for YAP or AREG expression and VIII CN schwannoma volume. CONCLUSIONS: The immunohistochemical expression of TAZ (but not YAP or AREG) correlated significantly with schwannoma volume measured on ceMRI. Further investigations are needed to identify the biological factors influencing tumor proliferation (ideally secreted proteins like AREG) that might be detected using non-invasive approaches (i.e., blood samples).

Expression of alarin in ependymoma and choroid plexus tumors.

Alarin, a 25 amino acid splice variant of the galanin-like peptide, was originally discovered in gangliocytes of neuroblastic tumors and shown to be expressed in ganglioneuroblastoma and ganglioneuroma but not in undifferentiated neuroblastoma. Recently, in vivo studies have elucidated the physiological functions of alarin in the central nervous system (CNS). Alarin was shown to stimulate food intake, increase body weight, induce luteinizing hormone secretion and stimulate fos-expression in rats; the anatomical localization for these functions correlates well with the varied distribution of the alarin peptide in the brain. Because alarin was originally detected in neuroblastic tumors and is present in a wide range of nuclei in the CNS, we determined in the present study the expression of alarin in a variety of CNS tumors. Immunohistochemical analysis of 179 tumor samples resulted in different alarin-like immunoreactivity (alarin-LI) intensities, which were score-rated from 0 (no alarin stainin), 1 (low intensity), 2 (medium intensity) to 3 (high intensity). Immunohistochemical analyses revealed score 2 or 3 alarin-LI in all choroid plexus tumors (100 %, 7/7) and in the majority of ependymomas (90 %, 52/58), but only in a minority of astrocytomas (15 %, 5/33), meningiomas (14 %, 7/49) and tumors of the cranial nerves (7 %, 1/15). In oligodendrogliomas (0 %, 0/12) and oligoastrocytoma (0 %, 0/5) alarin-LI was not detectable. The high specificity (83 %) of alarin-LI suggests that it might be used as a diagnostic marker for ependymoma in differentiating them from other gliomas such as astrocytomas and oligodendrogliomas.

Assessment of antiangiogenic effect of imatinib mesylate on vestibular schwannoma tumors using in vivo corneal angiogenesis assay.

OBJECT: Angiogenesis and the platelet-derived growth factor (PDGF) pathway are active in the pathogenesis of vestibular schwannomas (VSs). The purpose of this study was to test whether imatinib mesylate (Gleevec), a PDGF receptor (PDGFR) blocker, reduces angiogenic capacity in sporadic VS and in VS associated with neurofibromatosis Type 2 (NF2) using a corneal angiogenesis assay. METHODS: From 121 VS tissue samples stored in the tumor bank at the Marmara University Institute of Neurological Sciences, 10 samples (6 from sporadic cases, 4 from NF2-associated cases) were selected at random for use in this study. Expression of PDGF-A and PDGF-B and their receptors was evaluated in sporadic and NF2-associated VS as well as in glioblastoma (GBM) and normal brain tissue by means of immunohistochemistry and Western blot analysis. Corneal angiogenesis assay was then used to evaluate the angiogenic capacity of tissue specimens from sporadic and NF2-associated VS with and without imatinib treatment as well as positive and negative controls (GBM and normal brain tissue). RESULTS: The angiogenic potential of the sporadic and NF2-associated VS tumor tissue differed significantly from that of the positive and negative control tissues (p <0.05). Furthermore, NF2-associated VS showed significantly lower angiogenic potential than sporadic VS (p <0.05). Imatinib treatment significantly reduced the angiogenic potential in both the sporadic VS and the NF2-associated VS groups. The level of PDGF-A and PDGFR-α as well as PDGF-B and PDGFR-ß expression in sporadic VS and NF2-associated VS also differed significantly (p <0.05) from the levels in controls. Additionally the level of PDGFR-ß was significantly higher in sporadic VS than in NF2-associated VS (p <0.05). CONCLUSIONS: The findings of this study indicate that NF2-associated VS has significantly more angiogenic potential than sporadic VS and normal brain tissue. Additionally, imatinib reduces the angiogenic activity of both sporadic and NF2-associated VS. The authors conclude that imatinib may be a potential treatment for VS, especially for NF2-associated lesions that cannot be cured with resection or radiosurgery.

Intraoperative biopsy of the major cranial nerves in the surgical strategy for adenoid cystic carcinoma close to the skull base.

OBJECTIVE: Adenoid cystic carcinoma of the salivary glands has a propensity for perineural invasion, which could favor spread along the major cranial nerves, sometimes to the skull base and through the foramina to the brain parenchyma. This study evaluated the relationship between neural spread and relapse in the skull base. STUDY DESIGN: During surgery, we performed multiple biopsies with extemporaneous examination of the major nerves close to the tumor to guide the surgical resection. RESULTS: The percentage of actuarial local control at 5 years for patients with a positive named nerve and skull base infiltration was 12.5%, compared with 90.0% in patients who were named nerve-negative and without infiltration of the skull base (P = .001). CONCLUSIONS: Our study shows that local control of disease for patients who are named nerve-positive with skull base infiltration is significantly more complex compared with patients who are named nerve-negative without infiltration of the skull base.

WT1 expression in normal and neoplastic cranial and peripheral nerves is independent of grade of malignancy.

OBJECTIVE: Wilms' tumor protein (WT1) expression is usually absent in normal glial cells of the CNS but is highly upregulated in brain tumor cells and its expression correlates with tumor grade. However, knowledge on WT1 expression in tumors of the peripheral nerve system (PNS) is limited. As WT1 antibodies not only serve as biomarker for cancerous tissue but also are considered for cancer immunotherapy, knowledge of WT1 expression in tumorous and normal peripheral nerve tissue is important for therapeutical purposes. METHODS: We analyze the immunohistochemical expression of WT1 in 101 samples consisting of 13 normal nerves, 10 neurofibromas, 69 schwannomas and 9 malignant peripheral nerve sheath tumors (MPNST). Tumor samples included 14 specimen from patients with a proven neurocutaneous disorder (neurofibromatosis type 1 and 2) and 3 cases of schwannomatosis. In 50 vestibular schwannomas tumor growth extension was correlated to WT1 expression. RESULTS: WT1 expression is present in Schwann cells of the majority of normal human nerves (11/13). In peripheral nerve sheath tumors, cytoplasmic WT1 protein is expressed in the cytoplasm of the neoplastic cells in all tumors, including MPNST, neurofibromas and schwannomas. The WT1 expression is independent of tumor malignancy or tumor growth extension and is not associated with a neurocutaneous disorder. CONCLUSION: WT1 expression in normal and neoplastic tissue differs in the peripheral and the central nervous system. These findings may point to a different functional role of WT1 in the PNS and the CNS.

Contralateral cranial polyneuropathy due to perineural invasion by a cutaneous squamous cell carcinoma.

Cutaneous malignancies may spread to underlying nerves, a process known as perineural invasion (PNI). We report a patient who was found to have PNI presenting as a cranial polyneuropathy on the contralateral side of the face many years after the resection of a squamous cell carcinoma. All diagnostic testing was unrevealing until nerve biopsy was performed. This emphasizes the long asymptomatic period between treatment of a cutaneous malignancy and detection of PNI, and the development of PNI at a site distant from the original malignancy. Biopsy of a clinically involved nerve may permit diagnosis of PNI when other studies are normal.

Immunohistochemical analysis of the purinoceptor P2X7 in human lingual nerve neuromas.

AIMS: Recent evidence suggests that the purinoceptor P2X7 may be involved in the development of dysesthesia following nerve injury, therefore, the aim of the present study was to investigate whether a correlation exists between the level of P2X7 receptor expression in damaged human lingual nerves and the severity of the patients' symptoms. METHODS: Neuroma-in-continuity specimens were obtained from patients undergoing surgical repair of the damaged lingual nerve. Specimens were categorized preoperatively according to the presence or absence of dysesthesia, and visual analog scales scores were used to record the degree of pain, tingling, and discomfort. Indirect immunofluorescence using antibodies raised against S-100 (a Schwann cell marker) and P2X7 was employed to quantify the percentage area of S-100 positive cells that also expressed P2X7. RESULTS: P2X7 was found to be expressed in Schwann cells of lingual nerve neuromas. No significant difference was found between the level of P2X7 expression in patients with or without symptoms of dysesthesia, and no relationship was observed between P2X7 expression and VAS scores for pain, tingling, or discomfort. No correlation was found between P2X7 expression and the time between initial injury and nerve repair. CONCLUSION: These data show that P2X7 is expressed in human lingual nerve neuromas from patients with and without dysesthesia. It therefore appears that the level of P2X7 expression at the injury site may not be linked to the maintenance of neuropathic pain after lingual nerve injury.

Malignant peripheral nerve sheath tumors of cranial nerves and intracranial contents: a clinicopathologic study of 17 cases.

Malignant peripheral nerve sheath tumors (MPNSTs) arising from cranial nerves or their branches are very uncommon. The literature consists mainly of isolated case reports and small series. We identified 17 such cases in 14 males and 3 females. With one exception, the tumors affected adults (age range 5 to 69 y, mean 39, median 32). Sites of involvement included vestibular nerves (n=6), vagal nerves (n=4), facial nerves (n=3) (1 centered in the geniculate ganglion), and 2 unspecified cranial nerves in the posterior fossa. In addition, 1 tumor involved the optic chiasm (n=1). Only 1 tumor arose in brain parenchyma of (frontal lobe). All but 3 lesions were intracranial. Five tumors arose in patients who satisfied clinical criteria for neurofibromatosis type 1 (NF1). One patient with a vestibular tumor and presumed NF2 had previously undergone resection of a contralateral vestibular cellular schwannoma. One posterior fossa tumor was a malignant melanotic schwannoma. Four patients had postirradiation malignant peripheral nerve sheath tumors, 2 having been treated for optic chiasm glioma, both being NF1 affected. One patient was irradiated for hypothalamic pilocytic astrocytoma and another for cervical Hodgkin disease. Identifiable precursor lesions included schwannoma (n=4), plexiform neurofibroma (n=2), and solitary intraneural neurofibroma (n=2). All tumors were histologically high grade (6 grade III and 10 grade IV). Three tumors showed heterologous elements, 2 osseous, and 1 rhabdomyoblastic. More often scattered than diffuse, S-100 protein staining was noted in 11 of 16 tumors and variable collagen IV staining in 10 of the 16. Immunoreactivity for p53 protein was diffuse and strong in 7 of 11 tumors. Twelve patients died within 17 months to 3 years of diagnosis, 1 was lost to follow-up, 2 are very recent cases, and 2 patients are currently alive, 1 after 2 recurrences, and another with spinal leptomeningeal metastases. Malignant cranial nerve sheath tumors are rare and are associated with the same poor prognosis as those of spinal nerves at other sites.

Immunohistochemical analysis supports a role for INI1/SMARCB1 in hereditary forms of schwannomas, but not in solitary, sporadic schwannomas.

The INI1/SMARCB1 protein product (INI1), a component of a transcription complex, was recently implicated in the pathogenesis of schwannomas in two members of a single family with familial schwannomatosis. Tumors were found to have both constitutional and somatic mutations of the SMARCB1 gene and showed a mosaic pattern of loss of INI1 expression by immunohistochemistry, suggesting a tumor composition of mixed null and haploinsufficient cells. To determine if this finding could be extended to all tumors arising in familial schwannomatosis, and how it compares with other multiple schwannoma syndromes [sporadic schwannomatosis and neurofibromatosis 2 (NF2)] as well as to sporadic, solitary schwannomas, we performed an immunohistochemistry analysis on 45 schwannomas from patients with multiple schwannoma syndromes and on 38 solitary, sporadic schwannomas from non-syndromic patients. A mosaic pattern of INI1 expression was seen in 93% of tumors from familial schwannomatosis patients, 55% of tumors from sporadic schwannomatosis, 83% of NF2-associated tumors and only 5% of solitary, sporadic schwannomas. These results confirm a role for INI1/SMARCB1 in multiple schwannoma syndromes and suggest that a different pathway of tumorigenesis occurs in solitary, sporadic tumors.

Expression of ErbB-1 and 2 in vestibular schwannomas.

ErbB-1 and 2 are receptor tyrosine kinases expressed in malignant tumours. Heterodimers of the ErbB family confer aggressive malignant behaviour, but homodimers are regarded as being less active. Using immunohistochemistry and Western blot techniques we have shown an increased expression of ErbB-2 and no expression of ErbB-1 in vestibular schwannomas (VS). Immunoprecipitation of the ErbB-2 in VS showed less activity when compared to glioblastoma multiforme. These findings implicate a functional role of ErbB-2 in the benign nature of VS and that a rationale for using ErbB targeted therapies in VS may be warranted.

Expression of VEGF and its receptor genes in intracranial schwannomas.

Vascular endothelial growth factor (VEGF) is considered to be a major regulator of angiogenesis in various brain tumors. In this study, we determined the expression levels of VEGF, and vascular endothelial growth factor receptor (VEGFR)-1 and -2 mRNA in 46 intracranial schwannomas by quantitative real-time PCR, and correlated these with various clinical factors or other molecular markers. We found that these tumors expressed significant amounts of VEGF mRNA in comparison with other brain tumors, including malignant gliomas and meningiomas. In addition, we performed immunohistochemical studies for VEGF and VEGFR-1, and confirmed that these tumors prominently express these proteins. The expression levels of VEGF and VEGFR-1 mRNA in recurrent tumors were higher than those in primary tumors. When we divided patients into two groups according to VEGF mRNA expression in the tumor, there was no significant difference in patient age, gender, or cranial nerves of origin between groups; however, the tumor volume tended to be larger in the high VEGF group than in the low VEGF group. The levels of VEGFR-1 mRNA and neurofibromatosis-2 mRNA in the high VEGF group were significantly greater than those in the low VEGF group. Levels of VEGFR-2 mRNA and DNA topoisomerase IIalpha mRNA, and the MIB-1 labeling index in the high VEGF group were slightly higher than those in the low VEGF group; however, the difference was not statistically significant. Based on these observations, the significance of VEGF and its receptor genes in intracranial schwannomas is discussed.

Expression of transforming growth factor-beta receptor type 1 and type 2 in human sporadic vestibular Schwannoma.

Expression of the transforming growth factor-beta (TGF-beta) protein family in the peripheral nervous system is well established, but the role of their cognate receptors TGF-beta receptor type 1 (R1) and type 2 (R2) has been less well studied. TGF-beta plays an essential role in Schwann cell proliferation and differentiation, and is involved in neurotrophic effects of several neurotrophic substances. TGF-beta is also expressed in benign peripheral nervous system tumors such as vestibular schwannomas. In the present study, we aimed to detect TGF-beta R1 and R2 in a total of 40 sporadic vestibular schwannomas using immunohistochemistry, and correlated the findings to essential clinicopathologic data. TGF-beta, TGF-beta R1, and TGF-beta R2 mRNA was further analyzed by RT-PCR in six vestibular schwannomas. TGF-beta R1 immunoexpression was found in about 95% of the tumors. TGF-beta R1 was equally present in Antoni A and Antoni B areas of the tumors. TGF-beta R2 was found immunohistochemically in 77%. In addition, all tumors showed strong expression of TGF-beta. No correlation between TGF-beta R1 or R2 expression and clinicopathologic parameters such as age, sex, clinical symptoms, growth pattern, and proliferation acitivity as measured by Ki-67 (MIB-1) staining was found. Moreover, all schwannomas studied contained TGF-beta, TGF-beta R1, and TGF-beta R2 mRNA. Therefore, the TGF-beta/TGF-beta R1 and -R2 system is present in human schwannomas, but its biologic role for tumor development and growth remains unclear.

Na(v)1.7 sodium channel expression in human lingual nerve neuromas.

OBJECTIVE: Peripheral branches of the trigeminal nerve are often damaged during the removal of lower third molar teeth, and a small proportion of patients who sustain an injury develop persistent chronic pain. The cause of the pain is not clear and there are no satisfactory methods of treatment. The aim of the present study was to examine the expression of the sodium channel subtype Na(v)1.7 in damaged human lingual nerves, and to identify any association between Na(v)1.7 expression and reported symptoms of dysaesthesia. METHODS: Eleven neuromas-in-continuity (NICs) and 11 nerve-end neuromas (NENs) were studied, and were all obtained at the time of surgical repair of the damaged lingual nerve. Specimens were categorised as being obtained from patients with symptoms or without symptoms, according to the degree of pain, tingling or discomfort that had been experienced. The tissue was prepared and processed for indirect immunofluorescence, and image analysis was used to quantify the percentage area of PGP 9.5-labelled tissue that also contained Na(v)1.7. RESULTS: The results demonstrated that sodium channel Na(v)1.7 was expressed in human lingual nerve neuromas. There was no direct relationship between the level of expression of Na(v)1.7 and the patients' symptoms of dysaesthesia. However, in NICs there was found to be an inverse correlation between Na(v)1.7 and macrophage expression, and in symptomatic NICs a direct correlation was found between Na(v)1.7 expression and axonal apposition. CONCLUSIONS: These data suggest that Na(v)1.7 expression alone does not play a primary role in initiating the painful symptoms of dysaesthesia. The development of neuropathic pain may involve complex interactions including changes in ultrastructure and ion channel density.

Expression of EGFR and LRIG-1 in human trigeminal neurinoma.

The expression of epidermal growth factor receptor (EGFR) and leucine-rich repeats and immunoglobulin-like domain 1 (LRIG-1) in human trigeminal neurinoma was investigated and their effect on the origination and development of trigeminal neurinoma, and the relationship between them was studied. By using immunohistochemistry with tissue chip, the expression of EGFR and LRIG-1 was detected in 23 cases of trigeminal neurinoma. It was found that in the 23 cases, the expression rate of EGFR was 21.74%, while that of the LRIG-1 was 78.26%. There was a negative correlation between them. It was suggested that LRIG-1 might inhibit the malignant differentiation and proliferation of the trigeminal neurinoma possibly by the negative feedback loop of EGFR.

Aggressive vestibular schwannomas showing postoperative rapid growth - their association with decreased p27 expression.

Vestibular schwannomas (VSs) are relatively slow growing tumors. However, some rapidly regrow or recur after surgical resection. The objective of this study was to identify those molecular characteristics predicting rapid recurrence after surgical resection. Immunohistochemically determined expressions of several cell cycle regulators and apoptosis-associated proteins in 12 cases of aggressive VS (AVS) and in 15 control cases of usual VS (UVS) cases were compared. The expressions of p53 and Bax (pro-apoptotic protein), Bcl-2 (anti-apoptotic protein), Fas, and Fas-L (apoptotic death receptor and ligand), caspase 3 (apoptotic effector caspase proteins), and p27 and p21 (cyclin-dependent kinase inhibitors) were analyzed using tissue array blocks. Loss of p27 expression was observed in 8 of 12 AVS cases (67%) and in 3 UVS cases (20%); p21 was expressed in all cases. Loss of Bax was observed in 3 AVS and 3 UVS cases. The anti-apoptotic protein, Bcl-2, was expressed in 9 AVS (75%) and 11 UVS (73%), and p53, Fas-L, and caspase 3 were negative and Fas was positive in all AVS and UVS cases. Of these, only the loss of p27 was statistically significant (P = 0.02). The loss of p27 in AVS may explain the unusually high proliferative potential of AVS versus UVS, and p27 may be a predictor of VS aggressiveness. The expressions of other apoptosis associated proteins were not significantly different in the two groups. This may be the first report to identify a molecular entity associated with aggressive VS. However, further studies are required.

[Diagnosis of intracranial facial schwannoma: clinical, and radiological factors, and the value of immunohistochemistry]. / Diagnóstico del schwannoma intracraneal del nervio facial. Factores clínicos, radiológicos y valor de la inmunohistoquímica.

OBJECTIVE: To analyze the clinical, radiological, and pathological features which may be useful to differentiate intracranial schwannomas of the facial nerve from vestibular schwannomas. MATERIAL AND METHODS: A retrospective study of 91 patients undergoing surgery with a clinical suspicion of vestibular schwannoma is presented. Clinical and radiological features are analyzed. Immunohistochemistry for neurofilaments was performed in selected cases of unilateral vestibular schwannomas, bilateral vestibular schwannomas, and facial nerve schwannomas. RESULTS: Facial function was normal in 83% of patients with vestibular schwannoma. Both patients with facial schwannomas had preoperative House-Brackmann grade II facial function. MRI showed no main differences between facial and vestibular schwannomas. A positive immunostaining was found in unilateral vestibular schwannomas, bilateral vestibular schwannomas, and facial nerve schwannomas. CONCLUSION: There are no specific clinical, radiological, or pathological factors to accurately differentiate schwannomas of the facial nerve from vestibular schwannomas.

Inflammatory and anti-glioma effects of an adenovirus expressing human soluble Fms-like tyrosine kinase 3 ligand (hsFlt3L): treatment with hsFlt3L inhibits intracranial glioma progression.

Glioblastoma multiforme is an intracranial tumor that has very poor prognosis. Patients usually succumb to their disease 6 to 12 months after they are diagnosed despite very aggressive treatment modalities. We tested the efficacy of a potent differentiation and proliferation factor for the professional antigen-presenting dendritic cells (DCs), i.e., Flt3L, for its potential role as a novel therapy for gliomas. We investigated the ability of recombinant adenoviral vectors encoding human soluble Flt3L (hsFlt3L) to improve the survival of Lewis rats bearing intracranial syngeneic CNS-1 gliomas. We show that RAdhsFlt3L can improve survival in a dose-dependent manner. Seventy percent of rats survive when treated with 8 x 10(7) pfu RAdhsFlt3L (P < 0.0005). In addition we demonstrate in both naive Lewis rats and C57BL/6 mice the presence of increased numbers of cells bearing DC markers (OX62 and MHCII, in rats, or CD11C, 33D1, MHCII, and F4/80, but not DEC205, in mice) in sites of brain delivery of RAdhsFlt3L. These results show that expression of hsFlt3L in the brain leads to the presence of cells displaying DC markers. We demonstrate that treatment with hsFlt3L leads to inhibition of tumor growth and significantly increased life span of animals implanted with syngeneic CNS-1 glioma cells. Animals that had survived for long periods, i.e., 6 months, had eliminated the implanted tumors after neuropathological analysis; on the other hand, some of the 3-month survivors still appeared to harbor brain tumors. Our results have profound implications for immune-mediated brain tumor therapy and also suggest the ability to recruit DC-like cells within the brain parenchyma in response to the local expression of Flt3L from adenoviral vectors.