Risk of developing glioblastoma following non-CNS primary cancer: a SEER analysis between 2000 and 2018.

BACKGROUND: Patients with a prior malignancy are at elevated risk of developing subsequent primary malignancies (SPMs). However, the risk of developing subsequent primary glioblastoma (SPGBM) in patients with a prior cancer history is poorly understood. METHODS: We used the Surveillance, Epidemiology, and End Results (SEER) database and identified patients diagnosed with non-CNS malignancy between 2000 and 2018. We calculated a modified standardized incidence ratio (M-SIR), defined as the ratio of the incidence of SPGBM among patients with initial non-CNS malignancy to the incidence of GBM in the general population, stratified by sex latency, and initial tumor location. RESULTS: Of the 5,326,172 patients diagnosed with a primary non-CNS malignancy, 3559 patients developed SPGBM (0.07%). Among patients with SPGBM, 2312 (65.0%) were men, compared to 2,706,933 (50.8%) men in the total primary non-CNS malignancy cohort. The median age at diagnosis of SPGBM was 65 years. The mean latency between a prior non-CNS malignancy and developing a SPGBM was 67.3 months (interquartile range [IQR] 27-100). Overall, patients with a primary non-CNS malignancy had a significantly elevated M-SIR (1.13, 95% CI 1.09-1.16), with a 13% increased incidence of SPGBM when compared to the incidence of developing GBM in the age-matched general population. When stratified by non-CNS tumor location, patients diagnosed with primary melanoma, lymphoma, prostate, breast, renal, or endocrine malignancies had a higher M-SIR (M-SIR ranges: 1.09-2.15). Patients with lung cancers (M-SIR 0.82, 95% CI 0.68-0.99), or stomach cancers (M-SIR 0.47, 95% CI 0.24-0.82) demonstrated a lower M-SIR. CONCLUSION: Patients with a history of prior non-CNS malignancy are at an overall increased risk of developing SPGBM relative to the incidence of developing GBM in the general population. However, the incidence of SPGBM after prior non-CNS malignancy varies by primary tumor location, with some non-CNS malignancies demonstrating either increased or decreased predisposition for SPGBM depending on tumor origin. These findings merit future investigation into whether these relationships represent treatment effects or a previously unknown shared predisposition for glioblastoma and non-CNS malignancy.

Socio-economic disparities influence likelihood of post-operative radiation to resection cavities of metastatic brain tumors.

PURPOSE: Irradiating the surgical bed of resected brain metastases improves local and distant disease control. Over time, stereotactic radiosurgery (SRS) has replaced whole brain radiotherapy (WBRT) as the treatment standard of care because it minimizes long-term damage to neuro-cognition. Despite this data and growing adoption, socio-economic disparities in clinical access can result in sub-standard care for some patient populations. We aimed to analyze the clinical and socio-economic characteristics of patients who did not receive radiation after surgical resection of brain metastasis. METHODS: Our sample was obtained from Clinformatics® Data Mart Database and included all patients from 2004 to 2021 who did or did not receive radiation treatment within sixty days after resection of tumors metastatic to the brain. Regression analysis was done to identify factors responsible for loss to adjuvant radiation treatment. RESULTS: Of 8362 patients identified who had undergone craniotomy for resection of metastatic brain tumors, 3430 (41%) patients did not receive any radiation treatment. Compared to patients who did receive some form of radiation treatment (SRS or WBRT), patients who did not get any form of radiation were more likely to be older (p = 0.0189) and non-white (p = 0.008). Patients with Elixhauser Comorbidity Index ≥3 were less likely to receive radiation treatment (p < 0.01). Fewer patients with household income ≥ $75,000 did not receive radiation treatment (p < 0.01). CONCLUSION: Age, race, household income, and comorbidity status were associated with differential likelihood to receive post-operative radiation treatment.

Blocking the functional domain of TIP1 by antibodies sensitizes cancer to radiation therapy.

Non-small-cell lung cancer (NSCLC) and glioblastoma (GB) have poor prognoses. Discovery of new molecular targets is needed to improve therapy. Tax interacting protein 1 (TIP1), which plays a role in cancer progression, is overexpressed and radiation-inducible in NSCLC and GB. We evaluated the effect of an anti-TIP1 antibody alone and in combination with ionizing radiation (XRT) on NSCLC and GB in vitro and in vivo. NSCLC and GB cells were treated with anti-TIP1 antibodies and evaluated for proliferation, colony formation, endocytosis, and cell death. The efficacy of anti-TIP1 antibodies in combination with XRT on tumor growth was measured in mouse models of NSCLC and GB. mRNA sequencing was performed to understand the molecular mechanisms involved in the action of anti-TIP1 antibodies. We found that targeting the functional domain of TIP1 leads to endocytosis of the anti-TIP1 antibody followed by reduced proliferation and increased apoptosis-mediated cell death. Anti-TIP1 antibodies bound specifically (with high affinity) to cancer cells and synergized with XRT to significantly increase cytotoxicity in vitro and reduce tumor growth in mouse models of NSCLC and GB. Importantly, downregulation of cancer survival signaling pathways was found in vitro and in vivo following treatment with anti-TIP1 antibodies. TIP1 is a new therapeutic target for cancer treatment. Antibodies targeting the functional domain of TIP1 exhibited antitumor activity and enhanced the efficacy of radiation both in vitro and in vivo. Anti-TIP1 antibodies interrupt TIP1 function and are effective cancer therapy alone or in combination with XRT in mouse models of human cancer.

Stereotactic radiosurgery for sarcoma metastases to the brain: a single-institution experience.

OBJECTIVE: Brain metastases (BMs) secondary to sarcoma are rare, and their incidence ranges from 1% to 8% of all bone and soft tissue sarcomas. Although stereotactic radiosurgery (SRS) is widely used for BMs, only a few papers have reported on SRS for sarcoma metastasizing to the brain. The purpose of this study was to evaluate the safety and effectiveness of SRS for sarcoma BM. METHODS: The authors retrospectively reviewed the clinical and radiological outcomes of patients with BM secondary to histopathologically confirmed sarcoma treated with SRS, either as primary treatment or as adjuvant therapy after surgery, at their institution between January 2005 and September 2022. They also compared the outcomes of patients with hemorrhagic lesions and of those without. RESULTS: Twenty-three patients (9 females) with 150 BMs secondary to sarcoma were treated with CyberKnife SRS. Median age at the time of treatment was 48.22 years (range 4-76 years). The most common primary tumor sites were the heart, lungs, uterus, upper extremities, chest wall, and head and neck. The median Karnofsky Performance Status on presentation was 73.28 (range 40-100). Eight patients underwent SRS as a primary treatment and 15 as adjuvant therapy to the resection cavity. The median tumor volume was 24.1 cm3 (range 0.1-150.3 cm3), the median marginal dose was 24 Gy (range 18-30 Gy) delivered in a median of 1 fraction (range 1-5) to a median isodose line of 76%. The median follow-up was 8 months (range 2-40 months). Median progression-free survival and overall survival were 5.3 months (range 0.4-32 months) and 8.2 months (range 0.1-40), respectively. The 3-, 6-, and 12-month local tumor control (LTC) rates for all lesions were respectively 78%, 52%, and 30%. There were no radiation-induced adverse effects. LTC at the 3-, 6-, and 12-month follow-ups was better in patients without hemorrhagic lesions (100%, 70%, and 40%, respectively) than in those with hemorrhagic lesions (68%, 38%, and 23%, respectively). CONCLUSIONS: SRS, both as a primary treatment and as adjuvant therapy to the resection cavity after surgery, is a safe and relatively effective treatment modality for sarcoma BMs. Nonhemorrhagic lesions show better LTC than hemorrhagic lesions. Larger studies aiming to validate these results are encouraged.

Understanding the Ghanaian Neurosurgical Literature: A Scoping Review and Bibliometric Analysis.

BACKGROUND: Research serves to bolster clinical neurosurgery by critically assessing various disease pathologies, while identifying important challenges and opportunities. However, there is limited information on the landscape of the Ghanaian neurosurgical literature. METHODS: A scoping review and bibliometric analysis was conducted in accordance with PRISMA guidelines. PubMed, Embase, Global Index Medicus, and Web of Science electronic databases were searched from inception until December 21, 2021 for English language articles about neurosurgery in Ghana. RESULTS: 927 articles were identified and 66 were ultimately included in the analysis. A majority of them, 42.4%, were retrospective cohort studies, with 62.1% published after 2010. There were no randomized controlled or basic science studies. Most articles were published in the West African Journal of Medicine (24.2%) and non-infectious/non-traumatic spinal pathology was the most commonly discussed topic (22.7%); 66.7% of articles included only authors affiliated with Ghanaian institutions, and international collaborators frequently originated from the United States (15.9%). Only 22.7% of the manuscripts reported a funding source. Commonly reported challenges included limited sample sizes, delays in diagnosis and treatment, and lack of proper diagnostic tools and specialized care. CONCLUSIONS: This review revealed that while the Ghanaian academic neurosurgery output has been increasing over time, these have been limited to cohort studies largely assessing spine pathology. The Ghanaian neurosurgical research environment may be bolstered by an increase in research funding, the establishment of longitudinal clinical databases, training in research methodology, increased incentives for researchers, strengthening of research collaborative networks, and increased engagement of neurosurgical trainees in research.

Assessment of the Neurosurgical Capacity in Ghana: Challenges and Opportunities.

BACKGROUND: Low- and middle-income countries experience numerous challenges in the provision of neurosurgical care. However, limited information exists on the neurosurgical workforce and the constraints under which care is delivered in Ghana, West Africa. METHODS: A 19-item survey assessing neurosurgical workforce, infrastructure, and education was administered to Ghanaian consultant neurosurgeons and neurosurgeon trainees between November 8, 2021, and January 20, 2022. The data were analyzed using summary descriptions, and qualitative data were categorized into themes. RESULTS: There were 25 consultant neurosurgeons and 8 neurosurgical trainees (from 2 training centers) identified at 11 hospitals in Ghana totaling a workforce density of 1 neurosurgeon per 1,240,000. Most neurosurgical centers were located in Accra, the capital city. Almost half of the population did not have access to a hospital with a neurosurgeon in their region. Of hospitals, 82% had in-house computed tomography and/or magnetic resonance imaging scanners. In the operating room, most neurosurgeons had access to a high-speed drill (91%) but lacked microscopes and endoscopic sets (only 64% and 36% had these tools, respectively). There were no neurointensivists or neurological intensive care units in the entire country, and there was a paucity of neurovascular surgeries and functional neurosurgical procedures. CONCLUSIONS: The provision of neurosurgical care in Ghana has come a long way since the 1960s. However, the neurosurgical community continues to face significant challenges. Alleviating these barriers to care will call for systems-level changes that allow for the prioritization of neurosurgical care within the Ghanaian health care system.

Impact of socio-economic factors on radiation treatment after resection of metastatic brain tumors: trends from a private insurance database.

BACKGROUND: Stereotactic radiosurgery (SRS) to the surgical bed of resected brain metastases is now considered the standard of care due to its advantages over whole brain radiation therapy (WBRT). Despite the upward trend in SRS adoption since the 2000s, disparities have been reported suggesting that socio-economic factors can influence SRS utilization. OBJECTIVE: To analyze recent trends in SRS use and identify factors that influence treatment. METHODS: We conducted a retrospective cohort study with the Optum Commercial Claims and Encounters Database and included all patients from 2004 to 2021 who received SRS or WBRT within 60 days after resection of tumors metastatic to the brain. RESULTS: A total of 3495 patients met the inclusion and exclusion criteria. There were 1998 patients in the SRS group and 1497 patients in the WBRT group. SRS use now supersedes WBRT by a wide margin. Lung, breast and colon were the most common sites of primary tumor. Although we found no significant differences based on race among the treatment groups, patients with annual household income greater than $75,000 and those with some college or higher education are significantly more likely to receive SRS (OR 1.44 and 1.30; 95% CI 1.18-1.76 and 1.08-1.56; P = 0.001 and 0.005, respective). Patients with Elixhauser Comorbidity Index of three or more were significantly more likely to receive SRS treatment. CONCLUSION: The use of post-surgical SRS for brain metastasis has increased significantly over time, however education and income were associated with differential SRS utilization.

Electrophysiology and Structural Connectivity of the Posterior Hypothalamic Region: Much to Learn From a Rare Indication of Deep Brain Stimulation.

Cluster headache (CH) is among the most common and debilitating autonomic cephalalgias. We characterize clinical outcomes of deep brain stimulation (DBS) to the posterior hypothalamic region through a novel analysis of the electrophysiological topography and tractography-based structural connectivity. The left posterior hypothalamus was targeted ipsilateral to the refractory CH symptoms. Intraoperatively, field potentials were captured in 1 mm depth increments. Whole-brain probabilistic tractography was conducted to assess the structural connectivity of the estimated volume of activated tissue (VAT) associated with therapeutic response. Stimulation of the posterior hypothalamic region led to the resolution of CH symptoms, and this benefit has persisted for 1.5-years post-surgically. Active contacts were within the posterior hypothalamus and dorsoposterior border of the ventral anterior thalamus (VAp). Delta- (3 Hz) and alpha-band (8 Hz) powers increased and peaked with proximity to the posterior hypothalamus. In the posterior hypothalamus, the delta-band phase was coupled to beta-band amplitude, the latter of which has been shown to increase during CH attacks. Finally, we identified that the VAT encompassing these regions had a high proportion of streamlines of pain processing regions, including the insula, anterior cingulate gyrus, inferior parietal lobe, precentral gyrus, and the brainstem. Our unique case study of posterior hypothalamic region DBS supports durable efficacy and provides a platform using electrophysiological topography and structural connectivity, to improve mechanistic understanding of CH and this promising therapy.

Deep Brain Stimulation for Chronic Cluster Headache: A Review.

OBJECTIVES: Cluster headaches are a set of episodic and chronic pain syndromes that are sources of significant morbidity for patients. The standard of care for cluster headaches remains medication therapy, however a minority of patients will remain refractory to treatment despite changes to dosage and therapeutic combinations. In these patients, functional neuromodulation using Deep Brain Stimulation (DBS) presents the opportunity to alleviate the significant pain that is experienced by targeting the neurophysiological substrates that mediate pain. MATERIAL AND METHODS: We review the literature on chronic cluster headache, including the growing number of DBS case reports and series that describe the alleviation of pain in a majority of patients through conventional or endoventricular targeting of the posterior hypothalamus and ventral tegmental area, with a minimal side effect profile. RESULTS: In this review, the history and outcomes of DBS use for medication-refractory cluster headaches are examined, with discussion on future directions for improving this novel treatment modality and providing efficacious, longer-lasting pain relief in headache patients. CONCLUSION: In patients with chronic cluster headache, functional neuromodulation using DBS presents the opportunity to alleviate the significant pain that is experienced by targeting the neurophysiological substrates that mediate pain.

PERK Regulates Glioblastoma Sensitivity to ER Stress Although Promoting Radiation Resistance.

The aggressive nature and inherent therapeutic resistance of glioblastoma multiforme (GBM) has rendered the median survival of afflicted patients to 14 months. Therefore, it is imperative to understand the molecular biology of GBM to provide new treatment options to overcome this disease. It has been demonstrated that the protein kinase R-like endoplasmic reticulum kinase (PERK) pathway is an important regulator of the endoplasmic reticulum (ER) stress response. PERK signaling has been observed in other model systems after radiation; however, less is known in the context of GBM, which is frequently treated with radiation-based therapies. To investigate the significance of PERK, we studied activation of the PERK-eIF2α-ATF4 pathway in GBM after ionizing radiation (IR). By inhibiting PERK, it was determined that ionizing radiation (IR)-induced PERK activity led to eIF2α phosphorylation. IR enhanced the prodeath component of PERK signaling in cells treated with Sal003, an inhibitor of phospho-eIF2α phosphatase. Mechanistically, ATF4 mediated the prosurvival activity during the radiation response. The data support the notion that induction of ER stress signaling by radiation contributes to adaptive survival mechanisms during radiotherapy. The data also support a potential role for the PERK/eIF2α/ATF4 axis in modulating cell viability in irradiated GBM.Implications: The dual function of PERK as a mediator of survival and death may be exploited to enhance the efficacy of radiation therapy.Visual Overview: http://mcr.aacrjournals.org/content/16/10/1447/F1.large.jpg Mol Cancer Res; 16(10); 1447-53. ©2018 AACR.

Antibody Targeting GRP78 Enhances the Efficacy of Radiation Therapy in Human Glioblastoma and Non-Small Cell Lung Cancer Cell Lines and Tumor Models.

Purpose: Non-small cell lung cancer (NSCLC) and glioblastoma multiforme (GBM) have poor median survival. NSCLC and GBM overexpress glucose regulated protein 78 (GRP78), which has a role in radioresistance and recurrence. In this study, we determined the effect of anti-GRP78 antibody and the combined effect of the anti-GRP78 antibody with ionizing radiation (XRT) on NSCLC and GBM cell lines both in vitro and in vivoExperimental Design: NSCLC and GBM cancer cell lines were treated with anti-GRP78 antibodies and evaluated for proliferation, colony formation, cell death, and PI3K/Akt/mTOR signaling. The efficacy of anti-GRP78 antibodies on tumor growth in combination with XRT was determined in vivo in mouse xenograft models.Results: GBM and NSCLC cells treated with anti-GRP78 antibodies showed attenuated cell proliferation, colony formation, and enhanced apoptosis. GBM and NSCLC cells treated with anti-GRP78 antibodies also showed global suppression of PI3K/Akt/mTOR signaling. Combining antibody with XRT resulted in significant tumor growth delay in both NSCLC and GBM heterotopic tumor models.Conclusions: Antibodies targeting GRP78 exhibited antitumor activity and enhanced the efficacy of radiation in NSCLC and GBM both in vitro and in vivo GRP78 is a promising novel target, and anti-GRP78 antibodies could be used as an effective cancer therapy alone or in combination with XRT. Clin Cancer Res; 23(10); 2556-64. ©2016 AACR.

An NAD+-dependent transcriptional program governs self-renewal and radiation resistance in glioblastoma.

Accumulating evidence suggests cancer cells exhibit a dependency on metabolic pathways regulated by nicotinamide adenine dinucleotide (NAD+). Nevertheless, how the regulation of this metabolic cofactor interfaces with signal transduction networks remains poorly understood in glioblastoma. Here, we report nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting step in NAD+ synthesis, is highly expressed in glioblastoma tumors and patient-derived glioblastoma stem-like cells (GSCs). High NAMPT expression in tumors correlates with decreased patient survival. Pharmacological and genetic inhibition of NAMPT decreased NAD+ levels and GSC self-renewal capacity, and NAMPT knockdown inhibited the in vivo tumorigenicity of GSCs. Regulatory network analysis of RNA sequencing data using GSCs treated with NAMPT inhibitor identified transcription factor E2F2 as the center of a transcriptional hub in the NAD+-dependent network. Accordingly, we demonstrate E2F2 is required for GSC self-renewal. Downstream, E2F2 drives the transcription of members of the inhibitor of differentiation (ID) helix-loop-helix gene family. Finally, we find NAMPT mediates GSC radiation resistance. The identification of a NAMPT-E2F2-ID axis establishes a link between NAD+ metabolism and a self-renewal transcriptional program in glioblastoma, with therapeutic implications for this formidable cancer.

Laser interstitial thermal therapy for subependymal giant cell astrocytoma: technical case report.

Subependymal giant cell astrocytoma (SEGA) is a rare tumor occurring almost exclusively in patients with tuberous sclerosis complex. Although open resection remains the standard therapy, complication rates remain high. To minimize morbidity, less invasive approaches, such as endoscope-assisted resection, radiosurgery, and chemotherapy with mTOR pathway inhibitors, are also used to treat these lesions. Laser interstitial thermal therapy (LITT) is a relatively new modality that is increasingly used to treat a variety of intracranial lesions. In this report, the authors describe two pediatric cases of SEGA that were treated with LITT. In both patients the lesion responded well to this treatment modality, with tumor shrinkage observed on follow-up MRI. These cases highlight the potential of LITT to serve as a viable minimally invasive therapeutic approach to the management of SEGAs in the pediatric population.

Utilizing personalized stereotactic frames for laser interstitial thermal ablation of posterior fossa and mesiotemporal brain lesions: a single-institution series.

OBJECTIVE The precision of laser probe insertion for interstitial thermal therapy of deep-seated lesions is limited by the method of stereotactic guidance. The objective of this study was to evaluate the feasibility of customized STarFix 3D-printed stereotactic platforms to guide laser probe insertion into mesiotemporal and posterior fossa targets. METHODS The authors conducted a retrospective review of 5 patients (12-55 years of age) treated with laser interstitial thermal therapy (LITT) in which STarFix platforms were used for probe insertion. Bone fiducials were implanted in each patient's skull, and subsequent CT scans were used to guide the design of each platform and incorporate desired treatment trajectories. Once generated, the platforms were mounted on the patients' craniums and used to position the laser probe during surgery. Placement of the laser probe and the LITT procedure were monitored with intraoperative MRI. Perioperative and follow-up MRI were performed to identify and monitor changes in target lesions. RESULTS Accurate placement of the laser probe was observed in all cases. For all patients, thermal ablation was accomplished without intraoperative complications. Of the 4 patients with symptomatic lesions, 2 experienced complete resolution of symptoms, and 1 reported improved symptoms compared with baseline. CONCLUSIONS Customized stereotactic platforms were seamlessly incorporated into the authors' previously established LITT workflow and allowed for accurate treatment delivery.

Tumor-Specific Binding of Radiolabeled PEGylated GIRLRG Peptide: A Novel Agent for Targeting Cancers.

Cancer-specific targeting sparing normal tissues would significantly enhance cancer therapy outcomes and reduce cancer-related mortality. One approach is to target receptors or molecules that are specifically expressed on cancer cells. Peptides as cancer-specific targeting agents offer advantages such as ease of synthesis, low antigenicity, and enhanced diffusion into tissues. Glucose-regulated protein 78 (GRP78) is an endoplasmic reticulum stress chaperone that regulates the unfolded protein response and is overexpressed in various cancers. In this study, we evaluated GIRLRG peptide that specifically targets GRP78 for cancer-specific binding (in vitro) and noninvasive tumor imaging (in vivo). METHODS: GIRLRG peptide was modeled into the GRP78 ATPase domain using computational modeling. Surface plasmon resonance studies were performed to determine the affinity of GIRLRG peptide to GRP78 protein. GIRLRG was conjugated with PEG to prolong its circulation in mice. Tumor binding efficacy of PEG-GIRLRG peptide was evaluated in nude mice bearing heterotopic cervical (HT3), esophageal (OE33), pancreatic (BXPC3), lung (A549), and glioma (D54) tumors. Nano-SPECT/CT imaging of the mice was performed 48 and 72 h after injection with 111In-labeled PEG-GIRLRG or PEG-control peptide. Post-SPECT biodistribution studies were performed 96 h after injection of the radiolabeled peptides. RESULTS: Using molecular modeling and surface plasmon resonance, we identified that GIRLRG was binding with an affinity constant of 2.16 × 10-3 M in the ATPase domain of GRP78. GIRLRG peptide specifically bound to cervical, lung, esophageal, and glioma cells. SPECT imaging revealed that 111In-PEG-GIRLRG specifically bound to cervical, esophageal, pancreatic, lung, and brain tumors. Post-SPECT biodistribution data also validated the SPECT imaging results. CONCLUSION: GIRLRG peptide specifically binds to the ATPase domain of GRP78. Radiolabeled PEG-GIRLRG could be used to target various cancers. Further studies would be required to translate PEG-GIRLRG peptide into the clinic.

The ATF6 pathway of the ER stress response contributes to enhanced viability in glioblastoma.

Therapeutic resistance is a major barrier to improvement of outcomes for patients with glioblastoma. The endoplasmic reticulum stress response (ERSR) has been identified as a contributor to chemoresistance in glioblastoma; however the contributions of the ERSR to radioresistance have not been characterized. In this study we found that radiation can induce ER stress and downstream signaling associated with the ERSR. Induction of ER stress appears to be linked to changes in ROS balance secondary to irradiation. Furthermore, we observed global induction of genes downstream of the ERSR in irradiated glioblastoma. Knockdown of ATF6, a regulator of the ERSR, was sufficient to enhance radiation induced cell death. Also, we found that activation of ATF6 contributes to the radiation-induced upregulation of glucose regulated protein 78 (GRP78) and NOTCH1. Our results reveal ATF6 as a potential therapeutic target to enhance the efficacy of radiation therapy.

Autotaxin Inhibition with PF-8380 Enhances the Radiosensitivity of Human and Murine Glioblastoma Cell Lines.

PURPOSE: Glioblastoma multiforme (GBM) is an aggressive primary brain tumor that is radio-resistant and recurs despite aggressive surgery, chemo, and radiotherapy. Autotaxin (ATX) is over expressed in various cancers including GBM and is implicated in tumor progression, invasion, and angiogenesis. Using the ATX specific inhibitor, PF-8380, we studied ATX as a potential target to enhance radiosensitivity in GBM. METHODS AND MATERIALS: Mouse GL261 and Human U87-MG cells were used as GBM cell models. Clonogenic survival assays and tumor transwell invasion assays were performed using PF-8380 to evaluate role of ATX in survival and invasion. Radiation dependent activation of Akt was analyzed by immunoblotting. Tumor induced angiogenesis was studied using the dorsal skin fold model in GL261. Heterotopic mouse GL261 tumors were used to evaluate the efficacy of PF-8380 as a radiosensitizer. RESULTS: Pre-treatment of GL261 and U87-MG cells with 1 µM PF-8380 followed by 4 Gy irradiation resulted in decreased clonogenic survival, decreased migration (33% in GL261; P = 0.002 and 17.9% in U87-MG; P = 0.012), decreased invasion (35.6% in GL261; P = 0.0037 and 31.8% in U87-MG; P = 0.002), and attenuated radiation-induced Akt phosphorylation. In the tumor window model, inhibition of ATX abrogated radiation induced tumor neovascularization (65%; P = 0.011). In a heterotopic mouse GL261 tumors untreated mice took 11.2 days to reach a tumor volume of 7000 mm(3), however combination of PF-8380 (10 mg/kg) with irradiation (five fractions of 2 Gy) took more than 32 days to reach a tumor volume of 7000 mm(3). CONCLUSION: Inhibition of ATX by PF-8380 led to decreased invasion and enhanced radiosensitization of GBM cells. Radiation-induced activation of Akt was abrogated by inhibition of ATX. Furthermore, inhibition of ATX led to diminished tumor vascularity and delayed tumor growth. These results suggest that inhibition of ATX may ameliorate GBM response to radiotherapy.

High-throughput identification of putative receptors for cancer-binding peptides using biopanning and microarray analysis.

Phage-display peptide biopanning has been successfully used to identify cancer-targeting peptides in multiple models. For cancer-binding peptides, identification of the peptide receptor is necessary to demonstrate the mechanism of action and to further optimize specificity and target binding. The process of receptor identification can be slow and some peptides may turn out to bind ubiquitous proteins not suitable for further drug development. In this report, we describe a high-throughput method for screening a large number of peptides in parallel to identify peptide receptors, which we have termed "reverse biopanning." Peptides can then be selected for further development based on their receptor. To demonstrate this method, we screened a library of 39 peptides previously identified in our laboratory to bind specifically to cancers after irradiation. The reverse biopanning process identified 2 peptides, RKFLMTTRYSRV and KTAKKNVFFCSV, as candidate ligands for the protein tax interacting protein 1 (TIP-1), a protein previously identified in our laboratory to be expressed in tumors and upregulated after exposure to ionizing radiation. We used computational modeling as the initial method for rapid validation of peptide-TIP-1 binding. Pseudo-binding energies were calculated to be -360.645 kcal mol(-1), -487.239 kcal mol(-1), and -595.328 kcal mol(-1) for HVGGSSV, TTRYSRV, and NVFFCSV respectively, suggesting that the peptides would have at least similar, if not stronger, binding to TIP-1 compared to the known TIP-1 binding peptide HVGGSSV. We validated peptide binding in vitro using electrophoretic mobility shift assay, which showed strong binding of RKFLMTTRYSRV and the truncated form TTRYSRV. This method allows for the identification of many peptide receptors and subsequent selection of peptides for further drug development based on the peptide receptor.

Nucleophosmin serves as a rate-limiting nuclear export chaperone for the Mammalian ribosome.

Nucleophosmin (NPM) (B23) is an essential protein in mouse development and cell growth; however, it has been assigned numerous roles in very diverse cellular processes. Here, we present a unified mechanism for NPM's role in cell growth; NPM directs the nuclear export of both 40S and 60S ribosomal subunits. NPM interacts with rRNA and large and small ribosomal subunit proteins and also colocalizes with large and small ribosomal subunit proteins in the nucleolus, nucleus, and cytoplasm. The transduction of NPM shuttling-defective mutants or the loss of Npm1 inhibited the nuclear export of both the 40S and 60S ribosomal subunits, reduced the available pool of cytoplasmic polysomes, and diminished overall protein synthesis without affecting rRNA processing or ribosome assembly. While the inhibition of NPM shuttling can block cellular proliferation, the dramatic effects on ribosome export occur prior to cell cycle inhibition. Modest increases in NPM expression amplified the export of newly synthesized rRNAs, resulting in increased rates of protein synthesis and indicating that NPM is rate limiting in this pathway. These results support the idea that NPM-regulated ribosome export is a fundamental process in cell growth.