Neurofibromatosis type 2 (NF2) is an autosomal dominant genetic disorder resulting from germline mutations in the NF2 gene. Bilateral vestibular schwannomas, tumors on cranial nerve VIII, are pathognomonic for NF2 disease. Furthermore, schwannomas also commonly develop in other cranial nerves, dorsal root ganglia and peripheral nerves. These tumors are a major cause of morbidity and mortality, and medical therapies to treat them are limited. Animal models that accurately recapitulate the full anatomical spectrum of human NF2-related schwannomas, including the characteristic functional deficits in hearing and balance associated with cranial nerve VIII tumors, would allow systematic evaluation of experimental therapeutics prior to clinical use. Here, we present a genetically engineered NF2 mouse model generated through excision of the Nf2 gene driven by Cre expression under control of a tissue-restricted 3.9kbPeriostin promoter element. By 10 months of age, 100% of Postn-Cre; Nf2(flox/flox) mice develop spinal, peripheral and cranial nerve tumors histologically identical to human schwannomas. In addition, the development of cranial nerve VIII tumors correlates with functional impairments in hearing and balance, as measured by auditory brainstem response and vestibular testing. Overall, the Postn-Cre; Nf2(flox/flox) tumor model provides a novel tool for future mechanistic and therapeutic studies of NF2-associated schwannomas.

Neurofibromatosis type 2 (NF2) is an autosomal-dominant disease that results in the formation of bilateral vestibular schwannomas (VSs) and multiple meningiomas. Treatment options for NF2-associated tumors are limited, and to date, no medical therapies are FDA approved. The ideal chemotherapeutic agent would inhibit both VS and meningiomas simultaneously. The objectives of this study are (1) to test the efficacy of AR42, a novel histone deacetylase inhibitor, to inhibit VS and meningioma growth and (2) to investigate this drug's mechanisms of action. Primary cultures of human VS and meningioma cells were established. Nf2-deficient mouse schwannoma and benign human meningioma Ben-Men-1 cells were also cultured. Cells were treated with AR42, and the drug's effects on proliferation and the cell cycle were analyzed using a methanethiosulfonate assay and flow cytometry, respectively. Human phospho-kinase arrays and Western blots were used to evaluate the effects of AR42 on intracellular signaling. The in vivo efficacy of AR42 was investigated using schwannoma xenografts. Tumor volumes were quantified using high-field, volumetric MRI, and molecular target analysis was performed using immunohistochemistry. AR42 inhibited the growth of primary human VS and Nf2-deficient mouse schwannoma cells with a half maximal inhibitory concentration (IC(50)) of 500 nM and 250-350 nM, respectively. AR42 also inhibited primary meningioma cells and the benign meningioma cell line, Ben-Men-1, with IC(50) values of 1.5 µM and 1.0 µM, respectively. AR42 treatment induced cell-cycle arrest at G(2) and apoptosis in both VS and meningioma cells. Also, AR42 exposure decreased phosphorylated Akt in schwannoma and meningioma cells. In vivo treatment with AR42 inhibited the growth of schwannoma xenografts, induced apoptosis, and decreased Akt activation. The potent growth inhibitory activity of AR42 in schwannoma and meningioma cells suggests that AR42 should be further evaluated as a potential treatment for NF2-associated tumors.

OSA is highly prevalent among patients with sCSF leaks. All patients with sCSF leaks should undergo formal PSG testing. Future studies are needed to determine the role of OSA in the development of sCSF leaks.

Objective: To determine the audiologic improvement after middle cranial fossa (MCF) approach to repair spontaneous cerebrospinal fluid (sCSF) leaks Study Design: Retrospective cohort study Setting: Tertiary referral center Patients: Twenty-four consecutive patients (27 ears) with temporal bone sCSF leak over a 4year period. Patient age, gender, ethnicity, body mass index (BMI), location of CSF leak, recurrence of CSF leak, and presence of encephalocele(s) were recorded. Intervention: Audiometric testing in patients undergoing MCF repair of temporal bone sCSF leak. Main Outcome Measures: Comparison of preoperative and postoperative pure tone average (PTA), air bone gap (ABG), and word recognition score (WRS) in the sCSF leak ear.Results: Out of 27 ears, 55% had multiple tegmen defects and 82% had ≥1 encephaloceles.There were no recurrent CSF leaks at a median follow up of 4 months. The mean (SD) preoperative PTA and ABG were 40.58 [15.67] dB and 16.44 [6.93] dB, respectively. There was significant improvement in mean PTA (10.28 [8.01] dB; p < 0.001; Cohen d=0.95) and ABG (9.31 [7.16] dB; P <0.001; Cohen d=0.88) after sCSF repair. Mean WRS improved (by 3.07 [6.11] %; p=0.024; Cohen d=0.46) from a mean preoperative WRS of 93.16 [9.34] % to a mean postoperative WRS of 96.26 [6.49] %.Conclusions: MCF approach for repair of sCSF leaks yields significant improvement in conductive hearing loss and is highly effective in management of the entire lateral skull base where multiple bony defects are often identified.

Smooth muscle cells arise from different populations of precursor cells during embryonic development. The mechanisms that specify the smooth muscle cell phenotype in each of these populations of cells are largely unknown. In many tissues and organs, homeodomain transcription factors play a key role in directing cell specification. However, little is known about how these proteins regulate smooth muscle differentiation. Using degenerate reverse transcription-PCR coupled to cDNA library screening we identified two homeodomain proteins, Hoxa10 and Hoxb8, which are expressed in adult mouse smooth muscle tissues. All three of the previously described transcripts of the Hoxa10 gene, Hoxa10-1, Hoxa10-2, and Hoxa10-3, were identified. Hoxa10-1 directly activated the smooth muscle-specific telokin promoter but did not activate the SM22␣, smooth muscle ␣-actin, or smooth muscle myosin heavy chain promoters. Small interfering RNA-mediated knock-down of Hoxa10-1 demonstrated that Hoxa10-1 is required for high levels of telokin expression in smooth muscle cells from uterus and colon. On the other hand, Hoxb8 inhibited the activity of the telokin, SM22␣, and smooth muscle ␣-actin promoters. Cotransfection of Hoxa10-1 together with Hoxa10-2 or Hoxb8 suggested that Hoxa10-2 and Hoxb8 act as competitive inhibitors of Hoxa10-1. Results from gel mobility shift assays demonstrated that Hoxa10-1, Hoxa10-2, and Hoxb8 bind directly to multiple sites in the telokin promoter. Mutational analysis of telokin promoter reporter genes demonstrated that the three homeodomain protein binding sites located between ؊80 and ؊75, ؉2 and ؉6, and ؉14 and ؉17 were required for maximal promoter activation by Hoxa10-1 and maximal inhibition by Hoxb8. Together these data demonstrate that the genes encoding smooth musclerestricted proteins are direct transcriptional targets of clustered homeodomain proteins and that different homeodomain proteins have distinct effects on the promoters of these genes.