Expression of Cathepsins B, D, and G in WHO Grade I Meningioma

Aim: We have recently demonstrated the presence of putative tumor stem cells (TSCs) in World Health Organization (WHO) grade I meningioma (MG) localized to the microvessels, which expresses components of the renin-angiotensin system (RAS). The RAS is known to be dysregulated and promotes tumorigenesis in many cancer types, including glioblastoma. Cathepsins B, D, and G are isoenzymes that catalyze the production of angiotensin peptides, hence providing bypass loops for the RAS. This study investigated the expression of cathepsins B, D, and G in WHO grade I MG in relation to the putative TSC population we have previously demonstrated.Methods: 3,3-Diaminobenzidine (DAB) immunohistochemical (IHC) staining with antibodies for cathepsins B, D, and G was performed on WHO grade I MG tissue samples from 10 patients. Three of the MG samples subjected to DAB IHC staining underwent immunofluorescence (IF) IHC staining to investigate co-expression of each of these cathepsins using combinations of smooth muscle actin (SMA) and embryonic stem cell marker OCT4. NanoString mRNA expression (n = 6) and Western blotting (WB; n = 5) analyses, and enzyme activity assays (EAAs; n = 3), were performed on snap-frozen WHO grade I MG tissue samples to confirm transcriptional activation, protein expression, and functional activity of these proteins, respectively.Results: DAB IHC staining demonstrated expression of cathepsins B, D, and G in all 10 MG samples. NanoString mRNA expression and WB analyses showed transcriptional activation and protein expression of all three cathepsins, although cathepsin G was expressed at low levels. EAAs demonstrated that cathepsin B and cathepsin D were functionally active. IF IHC staining illustrated localization of cathepsin B and cathepsin D to the endothelium and SMA+ pericyte layer of the microvessels, while cathepsin G was localized to cells scattered within the interstitium, away from the microvessels.Conclusion: Cathepsin B and cathepsin D, and to a lesser extent cathepsin G, are expressed in WHO grade I MG. Cathepsin B and cathepsin D are enzymatically active and are localized to the putative TSC population on the microvessels, whereas cathepsin G was localized to cells scattered within the interstitium, These results suggest the presence of bypass loops for the RAS, within WHO grade I MG

Axl/Gas6/NFκB signalling in schwannoma pathological proliferation, adhesion and survival.

TAM family receptor tyrosine kinases comprising Tyro3 (Sky), Axl, and Mer are overexpressed in some cancers, correlate with multidrug resistance and contribute to tumourigenesis by regulating invasion, angiogenesis, cell survival and tumour growth. Mutations in the gene coding for a tumour suppressor merlin cause development of multiple tumours of the nervous system such as schwannomas, meningiomas and ependymomas occurring spontaneously or as part of a hereditary disease neurofibromatosis type 2. The benign character of merlin-deficient tumours makes them less responsive to chemotherapy. We previously showed that, amongst other growth factor receptors, TAM family receptors (Tyro3, Axl and Mer) are significantly overexpressed in schwannoma tissues. As Axl is negatively regulated by merlin and positively regulated by E3 ubiquitin ligase CRL4DCAF1, previously shown to be a key regulator in schwannoma growth we hypothesized that Axl is a good target to study in merlin-deficient tumours. Moreover, Axl positively regulates the oncogene Yes-associated protein, which is known to be under merlin regulation in schwannoma and is involved in increased proliferation of merlin-deficient meningioma and mesothelioma. Here, we demonstrated strong overexpression and activation of Axl receptor as well as its ligand Gas6 in human schwannoma primary cells compared to normal Schwann cells. We show that Gas6 is mitogenic and increases schwannoma cell-matrix adhesion and survival acting via Axl in schwannoma cells. Stimulation of the Gas6/Axl signalling pathway recruits Src, focal adhesion kinase (FAK) and NFκB. We showed that NFκB mediates Gas6/Axl-mediated overexpression of survivin, cyclin D1 and FAK, leading to enhanced survival, cell-matrix adhesion and proliferation of schwannoma. We conclude that Axl/FAK/Src/NFκB pathway is relevant in merlin-deficient tumours and is a potential therapeutic target for schwannoma and other merlin-deficient tumours

Endoscopic transsphenoidal resection of a mid-clival meningioma

Advances in transsphenoidal endoscopic surgery have allowed difficult clival tumours such as meningiomas causing effacement of the pons and basilar artery to be approached by this technique. We report a clival meningioma resected via a transsphenoidal endoscopic approach.Hamish Alexander, Simon Robinson, Agadha Wickremesekera, P.J. Wormal

Endoscopic endonasal transsphenoidal surgery: A mentoring surgical model

Background:  We report the experience of endoscopic endonasal transsphenoidal surgery (EETS) for resection of pituitary region tumours at Wellington, the central regional referral centre for neurosurgery in New Zealand, and discuss the collaborative mentoring surgical model that enhanced the learning experience. Method:  Between January 2007 and June 2009, a total of 47 operations on 46 patients were performed and reviewed retrospectively. All patients had perioperative clinical assessment, hormonal profile and magnetic resonance imaging studies for residual/recurrent disease. The collaborative model utilized two neurosurgeons with experience in the microsurgical resection of pituitary tumours: an endoscopic skull base fellowship trained rhinologist and an endoscopic skull base rhinologist with more experience who visited twice a year from Adelaide, Australia. Results:  The pathology results included: 30 non-functioning pituitary adenomas, 10 secreting pituitary adenomas, 3 meningiomas, 1 chordoma, 1 anterior skull base adenocarcinoma and 1 clival prostate metastasis. Complete tumour resection was intended and achieved in 38 cases. All 10 patients with secreting adenomas achieved improvement of hormonal profile. Nineteen out of 27 cases demonstrated improvement of vision. Perioperative complications included one epistaxis, three cerebrospinal fluid fistulae, one delayed chronic subdural haematoma and one persistent diabetes insipidus. Conclusion:  Our results highlight the value of a collaborative mentoring surgical model for a single centre adopting the endoscopic transsphenoidal technique and demonstrate that excellent EETS outcomes can be achieved in a smaller endoscopic skull base unit in Australasia during the learning phase.Joseph Y. M. Yang, Ingrid De Ruiter, Andrew Parker, Peter J. Wormald, Simon Robinson and Agadha Wickremeseker

Endoscopic surgery of skull base chordomas

Objective To assess our clinical experience in treating midline intracranial pathology using minimally invasive surgical techniques. Design Retrospective chart review of patients undergoing endoscopic endonasal resection of clival chordomas. Setting Two tertiary referral centers in Australia and New Zealand. Main Outcome Measures Patients were assessed by intraoperative findings (macroscopic resection rate, tumor size, and operative complications) and clinical outcomes (residual disease, postoperative complications, recurrence rate, and mortality). Results Fourteen patients underwent endoscopic resection of clival chordomas (seven primary, seven revision) with a mean follow-up of 41.45 months (3 to 104 months). Macroscopic resection rates were 71% and 29%, respectively. Mean operative time was 386 minutes. Overall cerebrospinal fluid (CSF) leak rate was 3/14 (21%) and, using the nasoseptal flap, it was 0/5 (0%). Two patients developed late recurrence; one died of disease and one was treated with intensity modulated radiation therapy. Overall mortality was 2/14 (14%). Conclusion Endoscopic resection of clival chordomas is a safe and viable alternative to the traditional open approach. The nasoseptal flap is an excellent method of obtaining a watertight skull base closure. Furthermore, this series highlighted the fact that the primary attempt at surgery offers the best chance to achieve a total resection.Neil C-W Tan, Yuresh Naidoo, Sakiko Oue, Hamish Alexander, Simon Robinson, Agadha Wickremesekera, Steve Floreani, Nick Vrodos, Steve Santoreneos, Eng Ooi, Matthew Mcdonald, Peter-John Wormal