Overcoming brain-derived therapeutic resistance in HER2+ breast cancer brain metastasis.

Brain metastasis of HER2+ breast cancer occurs in about 50% of all women with metastatic HER2+ breast cancer and confers poor prognosis for patients. Despite effective HER2-targeted treatments of peripheral HER2+ breast cancer with Trastuzumab +/-HER2 inhibitors, limited brain permeability renders these treatments inefficient for HER2+ breast cancer brain metastasis (BCBM). The scarcity of suitable patient-derived in-vivo models for HER2+ BCBM has compromised the study of molecular mechanisms that promote growth and therapeutic resistance in brain metastasis. We have generated and characterized new HER2+ BCBM cells (BCBM94) isolated from a patient HER2+ brain metastasis. Repeated hematogenic xenografting of BCBM94 consistently generated BCBM in mice. The clinically used receptor tyrosine kinase inhibitor (RTKi) Lapatinib blocked phosphorylation of all ErbB1-4 receptors and induced the intrinsic apoptosis pathway in BCBM94. Neuregulin-1 (NRG1), a ligand for ErbB3 and ErbB4 that is abundantly expressed in the brain, was able to rescue Lapatinib-induced apoptosis and clonogenic ability in BCBM94 and in HER2+ BT474. ErbB3 was essential to mediate the NRG1-induced survival pathway that involved PI3K-AKT signalling and the phosphorylation of BAD at serine 136 to prevent apoptosis. High throughput RTKi screening identified the brain penetrable Poziotinib as highly potent compound to reduce cell viability in HER2+ BCBM in the presence of NRG1. Successful in-vivo ablation of BCBM94- and BT474-derived HER2+ brain tumors was achieved upon two weeks of treatment with Poziotinib. MRI revealed BCBM remission upon poziotinib, but not with Lapatinib treatment. In conclusion, we have established a new patient-derived HER2+ BCBM in-vivo model and identified Poziotinib as highly efficacious RTKi with excellent brain penetrability that abrogated HER2+ BCBM brain tumors in our mouse models.

Adult gangliocytoma arising within the lateral ventricle: A case report and review of the literature.

BACKGROUND: Gangliocytomas are rare neuronal tumors with an incidence of <1% of all central nervous system (CNS) neoplasms. They occur mostly in the pediatric age group, localizing within the cerebral cortex, most often the temporal lobe. CASE DESCRIPTION: We report a case of an intracranial gangliocytoma arising within the lateral ventricle in a 66-year-old female. Magnetic resonance imaging of the brain showed a diffusely enhancing lobulated mass situated within the frontal horn of the right lateral ventricle with extension into the foramen of Monro and obstructive hydrocephalus. The patient underwent an interhemispheric transcallosal approach with gross total resection and relief of her hydrocephalus. Pathological examination showed clusters of highly pleomorphic neuron-like cells without evidence of neoplastic glial cells. Histopathological and immunohistochemistry findings were consistent with the diagnosis of gangliocytoma (World Health Organization Grade 1). CONCLUSION: Gangliocytomas are rare low-grade CNS neoplasms that can present in an older population within unusual locations and should be included within the differential whenever a suspicious lesion is encountered.

Awake Craniotomy Under 3-Tesla Intraoperative Magnetic Resonance Imaging: A Retrospective Descriptive Report and Canadian Institutional Experience.

BACKGROUND: The role of high-field 3-Tesla intraoperative magnetic resonance imaging (I-MRI) during awake craniotomy (AC) has not been extensively studied. We report the feasibility and safety of AC during 3-Tesla I-MRI. METHODS: This retrospective descriptive report compared 3 groups: AC with minimal sedation and I-MRI; I-MRI-guided craniotomy under general anesthesia (GA), and; AC without I-MRI. Perioperative factors, surgical, anesthetic and radiologic complications, and postoperative morbidity and mortality were recorded. RESULTS: Overall, 85 patients are included in this report. Five of 23 patients (22%) who underwent AC with I-MRI had anesthetic complications (nausea/vomiting and conversion to GA) compared with 3 of 40 (8%) who underwent I-MRI-guided craniotomy under GA (nausea/vomiting during extubation, and arrhythmia). Intraoperative surgical complications (seizures and speech deficits) occurred in 5 patients (22%) who underwent AC and I-MRI, excessive intraoperative bleeding occurred in 2 patients (5%) who had I-MRI-guided craniotomy under GA, and 4 of 22 (18%) patients who underwent AC without I-MRI experienced neurological complications (seizures, motor deficits, and transient loss of consciousness). Eight patients (20%) who had I-MRI with GA had postoperative complications, largely neurological. The duration of surgery and anesthesia were shortest in the group of patients receiving AC without I-MRI. Seventy-three percent of the patients in this group had residual tumor postoperatively compared with 44% and 38% in those having I-MRI with AC or GA, respectively. Patients who underwent I-MRI-guided craniotomy with GA had the highest morbidity (8%) at hospital discharge. CONCLUSIONS: Our institutional experience suggests that AC under 3-Tesla I-MRI could be an option for glioma resection, although firm conclusions cannot be drawn given the limited and heterogenous nature of our data. Future multicenter trials comparing anesthetic and imaging modalities for glioma resection are recommended.

Novel CTRP8-RXFP1-JAK3-STAT3 axis promotes Cdc42-dependent actin remodeling for enhanced filopodia formation and motility in human glioblastoma cells.

C1q tumor necrosis factor-related peptide 8 (CTRP8) is the least studied member of the C1Q-TNF-related peptide family. We identified CTRP8 as a ligand of the G protein-coupled receptor relaxin family peptide receptor 1 (RXFP1) in glioblastoma multiforme (GBM). The CTRP8-RXFP1 ligand-receptor system protects human GBM cells against the DNA-alkylating damage-inducing temozolomide (TMZ), the drug of choice for the treatment of patients with GBM. The DNA protective role of CTRP8 was dependent on a functional RXFP1-STAT3 signaling cascade and targeted the monofunctional glycosylase N-methylpurine DNA glycosylase (MPG) for more efficient base excision repair of TMZ-induced DNA-damaged sites. CTRP8 also improved the survival of GBM cells by upregulating anti-apoptotic BCl-2 and BCL-XL. Here, we have identified Janus-activated kinase 3 (JAK3) as a novel member of a novel CTRP8-RXFP1-JAK3-STAT3 signaling cascade that caused an increase in cellular protein content and activity of the small Rho GTPase Cdc42. This is associated with significant F-actin remodeling and increased GBM motility. Cdc42 was critically important for the upregulation of the actin nucleation complex N-Wiskott-Aldrich syndrome protein/Arp3/4 and actin elongation factor profilin-1. The activation of the RXFP1-JAK3-STAT3-Cdc42 axis by both RXFP1 agonists, CTRP8 and relaxin-2, caused extensive filopodia formation. This coincided with enhanced activity of ezrin, a key factor in tethering F-actin to the plasma membrane, and inhibition of the actin filament severing activity of cofilin. The F-actin remodeling and pro-migratory activities promoted by the novel RXFP1-JAK3-STAT3-Cdc42 axis were blocked by JAK3 inhibitor tofacitinib and STAT3 inhibitor STAT3 inhibitor VI. This provides a new rationale for the design of JAK3 and STAT3 inhibitors with better brain permeability for clinical treatment of the pervasive brain invasiveness of GBM.

Slow Off-Rate Modified Aptamer (SOMAmer) Proteomic Analysis of Patient-Derived Malignant Glioma Identifies Distinct Cellular Proteomes.

Malignant gliomas derive from brain glial cells and represent >75% of primary brain tumors. This includes anaplastic astrocytoma (grade III; AS), the most common and fatal glioblastoma multiforme (grade IV; GBM), and oligodendroglioma (ODG). We have generated patient-derived AS, GBM, and ODG cell models to study disease mechanisms and test patient-centered therapeutic strategies. We have used an aptamer-based high-throughput SOMAscan® 1.3K assay to determine the proteomic profiles of 1307 different analytes. SOMAscan® proteomes of AS and GBM self-organized into closely adjacent proteomes which were clearly distinct from ODG proteomes. GBM self-organized into four proteomic clusters of which SOMAscan® cluster 4 proteome predicted a highly inter-connected proteomic network. Several up- and down-regulated proteins relevant to glioma were successfully validated in GBM cell isolates across different SOMAscan® clusters and in corresponding GBM tissues. Slow off-rate modified aptamer proteomics is an attractive analytical tool for rapid proteomic stratification of different malignant gliomas and identified cluster-specific SOMAscan® signatures and functionalities in patient GBM cells.

C1q/TNF-related peptide 8 (CTRP8) promotes temozolomide resistance in human glioblastoma.

The C1q/TNF-related peptide 8 (CTRP8) has recently emerged as a novel ligand of the G protein-coupled receptor RXFP1 in the fatal brain tumor glioblastoma (GBM). We previously demonstrated that the CTRP8-RXFP1 ligand-receptor system promotes motility and matrix invasion of patient GBM and U87 MG cells by specific phosphorylation of PI3 kinase and protein kinase C. Here, we demonstrate a novel role for CTRP8 in protecting human GBM cells against the DNA alkylating damage of temozolomide (TMZ), the standard chemotherapy drug used to treat GBM. This DNA protective role of CTRP8 required a functional RXFP1-STAT3 signaling cascade in GBM cells. We identified N-methylpurine DNA glycosylase (MPG), a monofunctional glycosylase that initiates base excision repair pathway by generating an apurinic/apyrimidinic (AP) site, as a new CTRP8-RXFP1-STAT3 target in GBM. Upon TMZ exposure, treatment with CTRP8 reduced the formation of AP sites and double-strand DNA breaks in GBM cells. This CTRP8 effect was independent of cellular MGMT levels and was associated with decreased caspase 3/7 activity and increased survival of human GBM. CTRP8-induced RXFP1 activation caused an increase in cellular protein levels of the anti-apoptotic Bcl members and STAT3 targets Bcl-2 and Bcl-XL in human GBM. Collectively, our results demonstrate a novel multipronged and clinically relevant mechanism by which the CTRP8-RXFP1 ligand-receptor system exerts a DNA protective function against TMZ chemotherapeutic stress in GBM. This CTRP8-RXFP1-STAT3 axis is a novel determinant of TMZ responsiveness/chemoresistance and an emerging new drug target for improved treatment of human GBM.

Hemorrhagic stroke after Epley maneuver: a case report.

BACKGROUND: This is the first case to our knowledge of a serious adverse event following the Epley maneuver, which is the treatment of choice for benign paroxysmal positional vertigo (BPPV), the most common vestibular disorder in adults. CASE PRESENTATION: A 77 year old female presented for outpatient evaluation of vertigo at a tertiary otolaryngology clinic. She was found to have BPPV clinically, and elected to have a particle repositioning maneuver (Epley maneuver) performed in clinic. Immediately following Epley maneuver, she had severe nausea and vomiting, with evolving visual changes. A CT angiogram of the brain was performed urgently through the emergency department and demonstrated an acute intraparenchymal hemorrhage in the occipital lobe. After medical stabilization and rehabilitation, the patient continues to have a permanent visual field deficit. CONCLUSION: The Epley maneuver is safe and effective, and there are no prior reports of serious adverse events associated with its use. This case, in which a patient experienced a hemorrhagic stroke after undergoing the Epley maneuver, is the first and sole case in the medical literature of an Epley-associated serious adverse event. The indirect causation and extreme rarity of this event do not warrant any change to patterns of practice.

Dovitinib enhances temozolomide efficacy in glioblastoma cells.

The multikinase inhibitor and FDA-approved drug dovitinib (Dov) crosses the blood-brain barrier and was recently used as single drug application in clinical trials for GB patients with recurrent disease. The Dov-mediated molecular mechanisms in GB cells are unknown. We used GB patient cells and cell lines to show that Dov downregulated the stem cell protein Lin28 and its target high-mobility group protein A2 (HMGA2). The Dov-induced reduction in pSTAT3Tyr705 phosphorylation demonstrated that Dov negatively affects the STAT3/LIN28/Let-7/HMGA2 regulatory axis in GB cells. Consistent with the known function of LIN28 and HMGA2 in GB self-renewal, Dov reduced GB tumor sphere formation. Dov treatment also caused the downregulation of key base excision repair factors and O6 -methylguanine-DNA-methyltransferase (MGMT), which are known to have important roles in the repair of temozolomide (TMZ)-induced alkylating DNA damage. Combined Dov/TMZ treatment enhanced TMZ-induced DNA damage as quantified by nuclear γH2AX foci and comet assays, and increased GB cell apoptosis. Pretreatment of GB cells with Dov ('Dov priming') prior to TMZ treatment reduced GB cell viability independent of p53 status. Sequential treatment involving 'Dov priming' and alternating treatment cycles with TMZ and Dov substantially reduced long-term GB cell survival in MGMT+ patient GB cells. Our results may have immediate clinical implications to improve TMZ response in patients with LIN28+ /HMGA2+ GB, independent of their MGMT methylation status.

Diagnostic discrepancies in malignant astrocytoma due to limited small pathological tumor sample can be overcome by IDH1 testing.

The accurate grading of malignant astrocytomas has significant prognostic and therapeutic implications. Traditional histopathological grading can be challenging due to regional tumor heterogeneity, especially in scenarios where small amounts of tissue are available for pathologic review. Here, we hypothesized that a critical tumor resection volume is needed for correct grading of astrocytomas by histopathology. For insufficient tissue sampling, IDH1 molecular testing can act as a complementary marker to improve diagnostic accuracy. Volumetric analyses were obtained using preoperative and postoperative MRI images. Histological specimens were gathered from 403 patients with malignant astrocytoma who underwent craniotomy. IDH1 status was assessed by immunohistochemistry and sequencing. Patients with >20 cubic centimeters (cc) of the total tumor volume resected on MRI have higher rate of GBM diagnosis compared to <20 cc [odds ratio (OR) 2.57, 95% confidence interval (CI) 1.6-4.06, P < 0.0001]. The rate of IDH1 status remained constant regardless of the tumor volume resected (OR 0.81, 95% CI 0.48-1.36, P < 0.43). The rate of GBM diagnosis is twofold greater for individual surgical specimen >10 cc than those of lower volume (OR 2.48, 95% CI 1.88-3.28, P < 0.0001). Overall survival for AA patients with >20 cc tumor resection on MRI is significantly better than those with <20 cc tumor resected (P < 0.05). No volume-dependent differences were observed in patients with GBM (P < 0.4), IDH1 wild type (P < 0.1) or IDH1 mutation (P < 0.88). IDH1 status should be considered when total resection volume is <20 cc based on MRI analysis and for surgical specimen <10 cc to complement histopathologic diagnosis of malignant astrocytomas. In these specimens, under-diagnosis of GBM may occur when analysis is restricted to histopathology alone.

IDH1 mutant malignant astrocytomas are more amenable to surgical resection and have a survival benefit associated with maximal surgical resection.

BACKGROUND: IDH1 gene mutations identify gliomas with a distinct molecular evolutionary origin. We sought to determine the impact of surgical resection on survival after controlling for IDH1 status in malignant astrocytomas-World Health Organization grade III anaplastic astrocytomas and grade IV glioblastoma. METHODS: Clinical parameters including volumetric assessment of preoperative and postoperative MRI were recorded prospectively on 335 malignant astrocytoma patients: n = 128 anaplastic astrocytomas and n = 207 glioblastoma. IDH1 status was assessed by sequencing and immunohistochemistry. RESULTS: IDH1 mutation was independently associated with complete resection of enhancing disease (93% complete resections among mutants vs 67% among wild-type, P < .001), indicating IDH1 mutant gliomas were more amenable to resection. The impact of residual tumor on survival differed between IDH1 wild-type and mutant tumors. Complete resection of enhancing disease among IDH1 wild-type tumors was associated with a median survival of 19.6 months versus 10.7 months for incomplete resection; however, no survival benefit was observed in association with further resection of nonenhancing disease (minimization of total tumor volume). In contrast, IDH1 mutants displayed an additional survival benefit associated with maximal resection of total tumor volume (median survival 9.75 y for >5 cc residual vs not reached for <5 cc, P = .025). CONCLUSIONS: The survival benefit associated with surgical resection differs based on IDH1 genotype in malignant astrocytic gliomas. Therapeutic benefit from maximal surgical resection, including both enhancing and nonenhancing tumor, may contribute to the better prognosis observed in the IDH1 mutant subgroup. Thus, individualized surgical strategies for malignant astrocytoma may be considered based on IDH1 status.

Contribution of sex differences in the acute stress response to sex differences in water maze performance in the rat.

Male rats outperform females in spatial tasks, such as the water maze (WM). Female rats are known to have higher basal serum corticosterone (CORT) levels and to manifest a more rapid and stronger CORT response to novel stressors. Sex differences in stress responses to the handling and forced swimming in the WM task might contribute to the sex difference in WM performance. In Experiment 1, naive females were found to be impaired relative to naive males in swimming to a visible platform in a WM pool due to strongly thigmotaxic swimming by females. In Experiment 2, serum CORT, a physiological measure of stress, was highly elevated during and after WM training, with female > male values and strong inverse correlations between CORT and measures of WM performance in females. Familiarization with the WM pool and test procedures by strategies pretraining prior to spatial training reduced or eliminated the sex differences in the stress response and WM performance. In Experiment 3, adrenalectomy to eliminate the stress response eliminated sex differences in WM performance. Taken together, the results suggest that male and female rats may harbor brain circuitry that is equally capable of accurate spatial navigation and memory in the WM but which may be impaired to different degrees by the differential stress responses triggered by WM testing.