Role of stereotactic radiosurgery in meningiomas and vestibular schwannomas

Targeting MERTK on tumour cells and macrophages: a potential intervention for sporadic and NF2-related meningioma and schwannoma tumours

Meningioma and schwannoma are common tumours of the nervous system. They occur sporadically or as part of the hereditary NF2-related schwannomatosis syndrome. There is an unmet need for new effective drug treatments for both tumour types. In this paper, we demonstrate overexpression/activation of TAM (TYRO3/AXL/MERTK) receptors (TAMs) and overexpression/release of ligand GAS6 in patient-derived meningioma tumour cells and tissue. For the first time, we reveal the formation of MERTK/TYRO3 heterocomplexes in meningioma and schwannoma tissue. We demonstrate the dependence of AXL and TYRO3 expression on MERTK in both tumour types, as well as interdependency of MERTK and AXL expression in meningioma. We show that MERTK and AXL contribute to increased proliferation and survival of meningioma and schwannoma cells, which we inhibited in vitro using the MERTK/FLT3 inhibitor UNC2025 and the AXL inhibitor BGB324. UNC2025 was effective in both tumour types with superior efficacy over BGB324. Finally, we found that TAMs are expressed by tumour-associated macrophages in meningioma and schwannoma tumours and that UNC2025 strongly depleted macrophages in both tumour types.

Management of Cavernous Sinus Meningioma Presenting With Cerebrovascular Insufficiency Secondary to Cavernous Carotid Artery Occlusion: Report of 2 Cases

BACKGROUND

Surgical removal of cavernous sinus meningiomas is challenging and associated with high morbidities as a result of the anatomic location and the surrounding neurovascular structures that are often invaded or encased by the tumor. Advances in radiotherapy techniques have led to the adoption of more conservative approaches in the management of cavernous sinus meningioma. Internal carotid artery encasement and invasion has been documented in these cases; however, ischemic presentation secondary to internal carotid artery stenosis or occlusion by meningioma in the region of the cavernous sinus is rare, with only few cases reported in the literature.

OBJECTIVE

To report our surgical technique and experience with bypass grafting for cavernous sinus meningiomas that invade or narrow the internal carotid artery.

METHODS

We report 2 patients who presented with signs and symptoms attributed to cavernous carotid artery occlusion secondary to cavernous sinus meningioma in the last 5 yr. Both patients were treated with flow augmentation without surgical intervention for the cavernous sinus meningioma.

RESULTS

In both cases, the clinical and radiological signs of cerebrovascular insufficiency improved markedly, and the patients' tumors are currently being monitored.

CONCLUSION

Although the cerebrovascular insufficiency in this subset of patients is attributed to the occlusion of the cavernous carotid artery caused by the tumor, we propose treating those patients with flow augmentation first with or without radiation therapy when there is a clear imaging feature suggestive of meningioma in the absence of significant cranial nerve deficit.

Surgical Management and Outcome Experience of 53 Cerebellopontine Angle Meningiomas

Background Meningiomas follow schwannomas as the second most common cerebellopontine angle (CPA) tumors. We investigate the diagnosis, management, and prognosis of this disease. Methods We reviewed the cases with the CPA meningiomas in our institution in Shaanxi, China from January 2012 to December 2015. Charts were retrospectively examined and patients were divided into two groups: 1) surgical treatment with a retrosigmoid approach for tumor resection and 2) stereotactic radiosurgery treatment only. Patients were followed up and outpatient records were also reviewed. Results Forty-nine patients underwent surgical resection via the retrosigmoid approach, while the other four underwent Gamma Knife® stereotactic radiosurgery (Elekta AB, Stockholm, Sweden) only. The most common presenting symptoms included hearing loss/tinnitus, vertigo, and headache; only 8.2% were asymptomatic. The largest diameter and base of each tumor varied from 4.0 to 5.5 cm and 3.0 to 5.0 cm, respectively. The tumors extended into different directions, mainly towards the tentorium and internal acoustic meatus (IAM). Eighty-three percent of surgical patients had a gross total resection. One death occurred due to pulmonary inflammation. Tumor recurrence was noted in 6.1% of patients. Postoperative trigeminal disturbance, facial nerve palsy, and hearing deterioration or loss were the most common immediate and delayed postoperative complications; most patients partially or completely recovered after hospital discharge. Intraoperative neuro-electrophysiological monitoring, complete resection, and postoperative radiation were key factors for reducing complications and recurrence. Conclusions The retrosigmoid approach offers an ideal visual field for exposing and resecting CPA meningiomas in a large series of cases. In our experience, it is one of the most useful and commonly used surgical approaches for removing meningiomas of this region.

MicroRNA-18a regulates invasive meningiomas via hypoxia-inducible factor-1α

The aim of the present study was to investigate the effects of microRNA-18a (miR-18a) on the invasiveness and metastasis of invasive meningiomas and the underlying mechanism. A total of 69 patients with meningiomas (30 patients in the invasive meningioma group and 39 patients in the non-invasive meningioma group) and 48 cases in the control group were enrolled. Samples of meningioma tissues, serum and cerebrospinal fluid were collected. Reverse transcription-quantitative polymerase chain reaction was performed to quantify the expression levels of hypoxia-inducible factor-1α (HIF-1α) mRNA and miR-18a. Western blot analysis was used to determine protein expression levels of HIF-1α. The expression levels of HIF-1α mRNA and protein in all three types of sample from the invasive meningioma group were significantly higher compared with those in the control and non-invasive meningioma groups (P<0.05), and the expression levels of HIF-1α mRNA in the serum and cerebrospinal fluid of the non-invasive meningioma group were significantly higher compared with those in the control group (P<0.05). The expression levels of miR-18a in the invasive meningioma group were significantly reduced compared with those in the control and non-invasive meningioma groups (P<0.05), whereas the levels of miR-18a in the non-invasive meningioma group were significantly lower compared with those in the control group (P<0.05). The expression of HIF-1α is significantly upregulated in patients with invasive meningiomas, possibly due to the downregulation of miR-18a expression. Therefore, miR-18a may regulate invasive meningiomas via HIF-1α.