Clinical evidence that a dysregulated master neural network modulator may aid in diagnosing schizophrenia.

There are no validated biomarkers for schizophrenia (SCZ), a disorder linked to neural network dysfunction. We demonstrate that collapsin response mediator protein-2 (CRMP2), a master regulator of cytoskeleton and, hence, neural circuitry, may form the basis for a biomarker because its activity is uniquely imbalanced in SCZ patients. CRMP2's activity depends upon its phosphorylation state. While an equilibrium between inactive (phosphorylated) and active (nonphosphorylated) CRMP2 is present in unaffected individuals, we show that SCZ patients are characterized by excess active CRMP2. We examined CRMP2 levels first in postmortem brains (correlated with neuronal morphometrics) and then, because CRMP2 is expressed in lymphocytes as well, in the peripheral blood of SCZ patients versus age-matched unaffected controls. In the brains and, more starkly, in the lymphocytes of SCZ patients <40 y old, we observed that nonphosphorylated CRMP2 was higher than in controls, while phosphorylated CRMP2 remained unchanged from control. In the brain, these changes were associated with dendritic structural abnormalities. The abundance of active CRMP2 with insufficient opposing inactive p-CRMP2 yielded a unique lowering of the p-CRMP2:CRMP2 ratio in SCZ patients, implying a disruption in the normal equilibrium between active and inactive CRMP2. These clinical data suggest that measuring CRMP2 and p-CRMP2 in peripheral blood might reflect intracerebral processes and suggest a rapid, minimally invasive, sensitive, and specific adjunctive diagnostic aid for early SCZ: increased CRMP2 or a decreased p-CRMP2:CRMP2 ratio may help cinch the diagnosis in a newly presenting young patient suspected of SCZ (versus such mimics as mania in bipolar disorder, where the ratio is high).

Design and proof of concept for targeted phage-based COVID-19 vaccination strategies with a streamlined cold-free supply chain.

Development of effective vaccines against coronavirus disease 2019 (COVID-19) is a global imperative. Rapid immunization of the entire human population against a widespread, continually evolving, and highly pathogenic virus is an unprecedented challenge, and different vaccine approaches are being pursued. Engineered filamentous bacteriophage (phage) particles have unique potential in vaccine development due to their inherent immunogenicity, genetic plasticity, stability, cost-effectiveness for large-scale production, and proven safety profile in humans. Herein we report the development and initial evaluation of two targeted phage-based vaccination approaches against SARS-CoV-2: dual ligand peptide-targeted phage and adeno-associated virus/phage (AAVP) particles. For peptide-targeted phage, we performed structure-guided antigen design to select six solvent-exposed epitopes of the SARS-CoV-2 spike (S) protein. One of these epitopes displayed on the major capsid protein pVIII of phage induced a specific and sustained humoral response when injected in mice. These phage were further engineered to simultaneously display the peptide CAKSMGDIVC on the minor capsid protein pIII to enable their transport from the lung epithelium into the systemic circulation. Aerosolization of these "dual-display" phage into the lungs of mice generated a systemic and specific antibody response. In the second approach, targeted AAVP particles were engineered to deliver the entire S protein gene under the control of a constitutive CMV promoter. This induced tissue-specific transgene expression, stimulating a systemic S protein-specific antibody response in mice. With these proof-of-concept preclinical experiments, we show that both targeted phage- and AAVP-based particles serve as robust yet versatile platforms that can promptly yield COVID-19 vaccine prototypes for translational development.

Spatial and temporal dynamics of HDACs class IIa following mild traumatic brain injury in adult rats.

The fundamental role of epigenetic regulatory mechanisms involved in neuroplasticity and adaptive responses to traumatic brain injury (TBI) is gaining increased recognition. TBI-induced neurodegeneration is associated with several changes in the expression-activity of various epigenetic regulatory enzymes, including histone deacetylases (HDACs). In this study, PET/CT with 6-([18F]trifluoroacetamido)-1- hexanoicanilide ([18F]TFAHA) to image spatial and temporal dynamics of HDACs class IIa expression-activity in brains of adult rats subjected to a weight drop model of diffuse, non-penetrating, mild traumatic brain injury (mTBI). The mTBI model was validated by histopathological and immunohistochemical analyses of brain tissue sections for localization and magnitude of expression of heat-shock protein-70 kDa (HSP70), amyloid precursor protein (APP), cannabinoid receptor-2 (CB2), ionized calcium-binding adapter protein-1 (IBA1), histone deacetylase-4 and -5 (HDAC4 and HDAC5). In comparison to baseline, the expression-activities of HDAC4 and HDAC5 were downregulated in the hippocampus, nucleus accumbens, peri-3rd ventricular part of the thalamus, and substantia nigra at 1-3 days post mTBI, and remained low at 7-8 days post mTBI. Reduced levels of HDAC4 and HDAC5 expression observed in neurons of these brain regions post mTBI were associated with the reduced nuclear and neuropil levels of HDAC4 and HDAC5 with the shift to perinuclear localization of these enzymes. These results support the rationale for the development of therapeutic strategies to upregulate expression-activity of HDACs class IIa post-TBI. PET/CT (MRI) with [18F]TFAHA can facilitate the development and clinical translation of unique therapeutic approaches to upregulate the expression and activity of HDACs class IIa enzymes in the brain after TBI.

Amphibian regeneration and mammalian cancer: Similarities and contrasts from an evolutionary biology perspective: Comparing the regenerative potential of mammalian embryos and urodeles to develop effective strategies against human cancer.

Here we review and discuss the link between regeneration capacity and tumor suppression comparing mammals (embryos versus adults) with highly regenerative vertebrates. Similar to mammal embryo morphogenesis, in amphibians (essentially newts and salamanders) the reparative process relies on a precise molecular and cellular machinery capable of sensing abnormal signals and actively reprograming or eliminating them. As the embryo's evil twin, tumor also retains common functional attributes. The immune system plays a pivotal role in maintaining a physiological balance to provide surveillance against tumor initiation or to support its initiation and progression. We speculate that susceptibility to cancer development in adult mammals may be determined by the loss of an advanced regenerative capability during evolution and believe that gaining mechanistic insights into how regenerative capacity linked to tumor suppression is postnatally lost in mammals might illuminate an as yet unrecognized route to cancer treatment.

Chemical mutagenesis of a GPCR ligand: Detoxifying "inflammo-attraction" to direct therapeutic stem cell migration.

A transplanted stem cell's engagement with a pathologic niche is the first step in its restoring homeostasis to that site. Inflammatory chemokines are constitutively produced in such a niche; their binding to receptors on the stem cell helps direct that cell's "pathotropism." Neural stem cells (NSCs), which express CXCR4, migrate to sites of CNS injury or degeneration in part because astrocytes and vasculature produce the inflammatory chemokine CXCL12. Binding of CXCL12 to CXCR4 (a G protein-coupled receptor, GPCR) triggers repair processes within the NSC. Although a tool directing NSCs to where needed has been long-sought, one would not inject this chemokine in vivo because undesirable inflammation also follows CXCL12-CXCR4 coupling. Alternatively, we chemically "mutated" CXCL12, creating a CXCR4 agonist that contained a strong pure binding motif linked to a signaling motif devoid of sequences responsible for synthetic functions. This synthetic dual-moity CXCR4 agonist not only elicited more extensive and persistent human NSC migration and distribution than did native CXCL 12, but induced no host inflammation (or other adverse effects); rather, there was predominantly reparative gene expression. When co-administered with transplanted human induced pluripotent stem cell-derived hNSCs in a mouse model of a prototypical neurodegenerative disease, the agonist enhanced migration, dissemination, and integration of donor-derived cells into the diseased cerebral cortex (including as electrophysiologically-active cortical neurons) where their secreted cross-corrective enzyme mediated a therapeutic impact unachieved by cells alone. Such a "designer" cytokine receptor-agonist peptide illustrates that treatments can be controlled and optimized by exploiting fundamental stem cell properties (e.g., "inflammo-attraction").

A ligand motif enables differential vascular targeting of endothelial junctions between brain and retina.

Endothelial heterogeneity has important implications in health and disease. Molecular markers selectively expressed in the vasculature of different organs and tissues are currently being explored in targeted therapies with promising results in preclinical and clinical studies. Noteworthy is the role that combinatorial approaches such as phage display have had in identifying such markers by using phage as nanoparticles and surrogates for billions of different peptides, screening noninvasively the vascular lumen for binding sites. Here, we show that a new peptide motif that emerged from such combinatorial screening of the vasculature binds selectively to blood vessels in the brain in vivo but not to vessels in other organs. Peptides containing a conserved motif in which amino acids Phenylalanine-Arginine-Tryptophan (FRW) predominate could be visualized by transmission electron microscopy bound to the junctions between endothelial cells in all areas of the brain, including the optic nerve, but not in other barrier-containing tissues, such as intestines and testis. Remarkably, peptides containing the motif do not bind to vessels in the retina, implying an important molecular difference between these two vascular barriers. Furthermore, the peptide allows for in vivo imaging, demonstrating that new tools for studying and imaging the brain are likely to emerge from this motif.

Next-generation of targeted AAVP vectors for systemic transgene delivery against cancer.

Bacteriophage (phage) have attractive advantages as delivery systems compared with mammalian viruses, but have been considered poor vectors because they lack evolved strategies to confront and overcome mammalian cell barriers to infective agents. We reasoned that improved efficacy of delivery might be achieved through structural modification of the viral capsid to avoid pre- and postinternalization barriers to mammalian cell transduction. We generated multifunctional hybrid adeno-associated virus/phage (AAVP) particles to enable simultaneous display of targeting ligands on the phage's minor pIII proteins and also degradation-resistance motifs on the very numerous pVIII coat proteins. This genetic strategy of directed evolution bestows a next-generation of AAVP particles that feature resistance to fibrinogen adsorption or neutralizing antibodies and ability to escape endolysosomal degradation. This results in superior gene transfer efficacy in vitro and also in preclinical mouse models of rodent and human solid tumors. Thus, the unique functions of our next-generation AAVP particles enable improved targeted gene delivery to tumor cells.

MLH1-rheMac hereditary nonpolyposis colorectal cancer syndrome in rhesus macaques.

Over the past two decades, 33 cases of colonic adenocarcinomas have been diagnosed in rhesus macaques (Macaca mulatta) at the nonhuman primate colony of the Keeling Center for Comparative Medicine and Research at The University of Texas MD Anderson Cancer Center. The distinctive feature in these cases, based on PET/computed tomography (CT) imaging, was the presence of two or three tumor lesions in different locations, including proximal to the ileocecal juncture, proximal to the hepatic flexure, and/or in the sigmoid colon. These colon carcinoma lesions selectively accumulated [18F]fluorodeoxyglucose ([18F]FDG) and [18F]fluoroacetate ([18F]FACE) at high levels, reflecting elevated carbohydrate and fatty acid metabolism in these tumors. In contrast, the accumulation of [18F]fluorothymidine ([18F]FLT) was less significant, reflecting slow proliferative activity in these tumors. The diagnoses of colon carcinomas were confirmed by endoscopy. The expression of MLH1, MSH2, and MSH6 proteins and the degree of microsatellite instability (MSI) was assessed in colon carcinomas. The loss of MLH1 protein expression was observed in all tumors and was associated with a deletion mutation in the MLH1 promoter region and/or multiple single-nucleotide polymorphism (SNP) mutations in the MLH1 gene. All tumors exhibited various degrees of MSI. The pedigree analysis of this rhesus macaque population revealed several clusters of affected animals related to each other over several generations, suggesting an autosomal dominant transmission of susceptibility for colon cancer. The newly discovered hereditary nonpolyposis colorectal cancer syndrome in rhesus macaques, termed MLH1-rheMac, may serve as a model for development of novel approaches to diagnosis and therapy of Lynch syndrome in humans.

BMTP-11 is active in preclinical models of human osteosarcoma and a candidate targeted drug for clinical translation.

Osteosarcoma occurs predominantly in children and young adults. High-grade tumors require multidisciplinary treatment consisting of chemotherapy in the neoadjuvant and adjuvant settings, along with surgical intervention. Despite this approach, death from respiratory failure secondary to the development and progression of pulmonary metastases remains a significant problem. Here, we identify the IL-11 receptor α subunit (IL-11Rα) as a cell surface marker of tumor progression that correlates with poor prognosis in patients with osteosarcoma. We also show that both IL-11Rα and its ligand, IL-11, are specifically up-regulated in human metastatic osteosarcoma cell lines; engagement of this autocrine loop leads to tumor cell proliferation, invasion, and anchorage-independent growth in vitro. Consistently, IL-11Rα promotes lung colonization by human metastatic osteosarcoma cells in vivo in an orthotopic mouse model. Finally, we evaluate the IL-11Rα-targeted proapoptotic agent bone metastasis-targeting peptidomimetic (BMTP-11) in preclinical models of primary intratibial osteosarcomas, observing marked inhibition of both tumor growth and lung metastases. This effect was enhanced when BMTP-11 was combined with the chemotherapeutic drug gemcitabine. Our combined data support the development of approaches targeting IL-11Rα, and establish BMTP-11 as a leading drug candidate for clinical translation in patients with high-risk osteosarcoma.

Defining recovery neurobiology of injured spinal cord by synthetic matrix-assisted hMSC implantation.

Mesenchymal stromal stem cells (MSCs) isolated from adult tissues offer tangible potential for regenerative medicine, given their feasibility for autologous transplantation. MSC research shows encouraging results in experimental stroke, amyotrophic lateral sclerosis, and neurotrauma models. However, further translational progress has been hampered by poor MSC graft survival, jeopardizing cellular and molecular bases for neural repair in vivo. We have devised an adult human bone marrow MSC (hMSC) delivery formula by investigating molecular events involving hMSCs incorporated in a uniquely designed poly(lactic-co-glycolic) acid scaffold, a clinically safe polymer, following inflammatory exposures in a dorsal root ganglion organotypic coculture system. Also, in rat T9-T10 hemisection spinal cord injury (SCI), we demonstrated that the tailored scaffolding maintained hMSC stemness, engraftment, and led to robust motosensory improvement, neuropathic pain and tissue damage mitigation, and myelin preservation. The scaffolded nontransdifferentiated hMSCs exerted multimodal effects of neurotrophism, angiogenesis, neurogenesis, antiautoimmunity, and antiinflammation. Hindlimb locomotion was restored by reestablished integrity of submidbrain circuits of serotonergic reticulospinal innervation at lumbar levels, the propriospinal projection network, neuromuscular junction, and central pattern generator, providing a platform for investigating molecular events underlying the repair impact of nondifferentiated hMSCs. Our approach enabled investigation of recovery neurobiology components for injured adult mammalian spinal cord that are different from those involved in normal neural function. The uncovered neural circuits and their molecular and cellular targets offer a biological underpinning for development of clinical rehabilitation therapies to treat disabilities and complications of SCI.

Glucosylceramide synthase inhibition alleviates aberrations in synucleinopathy models.

Mutations in the glucocerebrosidase gene (GBA) confer a heightened risk of developing Parkinson's disease (PD) and other synucleinopathies, resulting in a lower age of onset and exacerbating disease progression. However, the precise mechanisms by which mutations in GBA increase PD risk and accelerate its progression remain unclear. Here, we investigated the merits of glucosylceramide synthase (GCS) inhibition as a potential treatment for synucleinopathies. Two murine models of synucleinopathy (a Gaucher-related synucleinopathy model, GbaD409V/D409V and a A53T-α-synuclein overexpressing model harboring wild-type alleles of GBA, A53T-SNCA mouse model) were exposed to a brain-penetrant GCS inhibitor, GZ667161. Treatment of GbaD409V/D409V mice with the GCS inhibitor reduced levels of glucosylceramide and glucosylsphingosine in the central nervous system (CNS), demonstrating target engagement. Remarkably, treatment with GZ667161 slowed the accumulation of hippocampal aggregates of α-synuclein, ubiquitin, and tau, and improved the associated memory deficits. Similarly, prolonged treatment of A53T-SNCA mice with GZ667161 reduced membrane-associated α-synuclein in the CNS and ameliorated cognitive deficits. The data support the contention that prolonged antagonism of GCS in the CNS can affect α-synuclein processing and improve behavioral outcomes. Hence, inhibition of GCS represents a disease-modifying therapeutic strategy for GBA-related synucleinopathies and conceivably for certain forms of sporadic disease.

Probing the lithium-response pathway in hiPSCs implicates the phosphoregulatory set-point for a cytoskeletal modulator in bipolar pathogenesis.

The molecular pathogenesis of bipolar disorder (BPD) is poorly understood. Using human-induced pluripotent stem cells (hiPSCs) to unravel such mechanisms in polygenic diseases is generally challenging. However, hiPSCs from BPD patients responsive to lithium offered unique opportunities to discern lithium's target and hence gain molecular insight into BPD. By profiling the proteomics of BDP-hiPSC-derived neurons, we found that lithium alters the phosphorylation state of collapsin response mediator protein-2 (CRMP2). Active nonphosphorylated CRMP2, which binds cytoskeleton, is present throughout the neuron; inactive phosphorylated CRMP2, which dissociates from cytoskeleton, exits dendritic spines. CRMP2 elimination yields aberrant dendritogenesis with diminished spine density and lost lithium responsiveness (LiR). The "set-point" for the ratio of pCRMP2:CRMP2 is elevated uniquely in hiPSC-derived neurons from LiR BPD patients, but not with other psychiatric (including lithium-nonresponsive BPD) and neurological disorders. Lithium (and other pathway modulators) lowers pCRMP2, increasing spine area and density. Human BPD brains show similarly elevated ratios and diminished spine densities; lithium therapy normalizes the ratios and spines. Consistent with such "spine-opathies," human LiR BPD neurons with abnormal ratios evince abnormally steep slopes for calcium flux; lithium normalizes both. Behaviorally, transgenic mice that reproduce lithium's postulated site-of-action in dephosphorylating CRMP2 emulate LiR in BPD. These data suggest that the "lithium response pathway" in BPD governs CRMP2's phosphorylation, which regulates cytoskeletal organization, particularly in spines, modulating neural networks. Aberrations in the posttranslational regulation of this developmentally critical molecule may underlie LiR BPD pathogenesis. Instructively, examining the proteomic profile in hiPSCs of a functional agent-even one whose mechanism-of-action is unknown-might reveal otherwise inscrutable intracellular pathogenic pathways.

Self-targeting of TNF-releasing cancer cells in preclinical models of primary and metastatic tumors.

Circulating cancer cells can putatively colonize distant organs to form metastases or to reinfiltrate primary tumors themselves through a process termed "tumor self-seeding." Here we exploit this biological attribute to deliver tumor necrosis factor alpha (TNF), a potent antitumor cytokine, directly to primary and metastatic tumors in a mechanism that we have defined as "tumor self-targeting." For this purpose, we genetically engineered mouse mammary adenocarcinoma (TSA), melanoma (B16-F10), and Lewis lung carcinoma cells to produce and release murine TNF. In a series of intervention trials, systemic administration of TNF-expressing tumor cells was associated with reduced growth of both primary tumors and metastatic colonies in immunocompetent mice. We show that these malignant cells home to tumors, locally release TNF, damage neovascular endothelium, and induce massive cancer cell apoptosis. We also demonstrate that such tumor-cell-mediated delivery avoids or minimizes common side effects often associated with TNF-based therapy, such as acute inflammation and weight loss. Our study provides proof of concept that genetically modified circulating tumor cells may serve as targeted vectors to deliver anticancer agents. In a clinical context, this unique paradigm represents a personalized approach to be translated into applications potentially using patient-derived circulating tumor cells as self-targeted vectors for drug delivery.

AAVP displaying octreotide for ligand-directed therapeutic transgene delivery in neuroendocrine tumors of the pancreas.

Patients with inoperable or unresectable pancreatic neuroendocrine tumors (NETs) have limited treatment options. These rare human tumors often express somatostatin receptors (SSTRs) and thus are clinically responsive to certain relatively stable somatostatin analogs, such as octreotide. Unfortunately, however, this tumor response is generally short-lived. Here we designed a hybrid adeno-associated virus and phage (AAVP) vector displaying biologically active octreotide on the viral surface for ligand-directed delivery, cell internalization, and transduction of an apoptosis-promoting tumor necrosis factor (TNF) transgene specifically to NETs. These functional attributes of AAVP-TNF particles displaying the octreotide peptide motif (termed Oct-AAVP-TNF) were confirmed in vitro, in SSTR type 2-expressing NET cells, and in vivo using cohorts of pancreatic NET-bearing Men1 tumor-suppressor gene KO mice, a transgenic model of functioning (i.e., insulin-secreting) tumors that genetically and clinically recapitulates the human disease. Finally, preclinical imaging and therapeutic experiments with pancreatic NET-bearing mice demonstrated that Oct-AAVP-TNF lowered tumor metabolism and insulin secretion, reduced tumor size, and improved mouse survival. Taken together, these proof-of-concept results establish Oct-AAVP-TNF as a strong therapeutic candidate for patients with NETs of the pancreas. More broadly, the demonstration that a known, short, biologically active motif can direct tumor targeting and receptor-mediated internalization of AAVP particles may streamline the potential utility of myriad other short peptide motifs and provide a blueprint for therapeutic applications in a variety of cancers and perhaps many nonmalignant diseases as well.

Integrated nanotechnology platform for tumor-targeted multimodal imaging and therapeutic cargo release.

A major challenge of targeted molecular imaging and drug delivery in cancer is establishing a functional combination of ligand-directed cargo with a triggered release system. Here we develop a hydrogel-based nanotechnology platform that integrates tumor targeting, photon-to-heat conversion, and triggered drug delivery within a single nanostructure to enable multimodal imaging and controlled release of therapeutic cargo. In proof-of-concept experiments, we show a broad range of ligand peptide-based applications with phage particles, heat-sensitive liposomes, or mesoporous silica nanoparticles that self-assemble into a hydrogel for tumor-targeted drug delivery. Because nanoparticles pack densely within the nanocarrier, their surface plasmon resonance shifts to near-infrared, thereby enabling a laser-mediated photothermal mechanism of cargo release. We demonstrate both noninvasive imaging and targeted drug delivery in preclinical mouse models of breast and prostate cancer. Finally, we applied mathematical modeling to predict and confirm tumor targeting and drug delivery. These results are meaningful steps toward the design and initial translation of an enabling nanotechnology platform with potential for broad clinical applications.

Towards a transcriptome-based theranostic platform for unfavorable breast cancer phenotypes.

Inflammatory breast carcinoma (IBC) is one of the most lethal forms of human breast cancer, and effective treatment for IBC is an unmet clinical need in contemporary oncology. Tumor-targeted theranostic approaches are emerging in precision medicine, but only a few specific biomarkers are available. Here we report up-regulation of the 78-kDa glucose-regulated protein (GRP78) in two independent discovery and validation sets of specimens derived from IBC patients, suggesting translational promise for clinical applications. We show that a GRP78-binding motif displayed on either bacteriophage or adeno-associated virus/phage (AAVP) particles or loop-grafted onto a human antibody fragment specifically targets orthotopic IBC and other aggressive breast cancer models in vivo. To evaluate the theranostic value, we used GRP78-targeting AAVP particles to deliver the human Herpes simplex virus thymidine kinase type-1 (HSVtk) transgene, obtaining simultaneous in vivo diagnosis through PET imaging and tumor treatment by selective activation of the prodrug ganciclovir at tumor sites. Translation of this AAVP system is expected simultaneously to image, monitor, and treat the IBC phenotype and possibly other aggressive (e.g., invasive and/or metastatic) subtypes of breast cancer, based on the inducible cell-surface expression of the stress-response chaperone GRP78, and possibily other cell-surface receptors in human tumors.

Targeted molecular-genetic imaging and ligand-directed therapy in aggressive variant prostate cancer.

Aggressive variant prostate cancers (AVPC) are a clinically defined group of tumors of heterogeneous morphologies, characterized by poor patient survival and for which limited diagnostic and treatment options are currently available. We show that the cell surface 78-kDa glucose-regulated protein (GRP78), a receptor that binds to phage-display-selected ligands, such as the SNTRVAP motif, is a candidate target in AVPC. We report the presence and accessibility of this receptor in clinical specimens from index patients. We also demonstrate that human AVPC cells displaying GRP78 on their surface could be effectively targeted both in vitro and in vivo by SNTRVAP, which also enabled specific delivery of siRNA species to tumor xenografts in mice. Finally, we evaluated ligand-directed strategies based on SNTRVAP-displaying adeno-associated virus/phage (AAVP) particles in mice bearing MDA-PCa-118b, a patient-derived xenograft (PDX) of castration-resistant prostate cancer bone metastasis that we exploited as a model of AVPC. For theranostic (a merging of the terms therapeutic and diagnostic) studies, GRP78-targeting AAVP particles served to deliver the human Herpes simplex virus thymidine kinase type-1 (HSVtk) gene, which has a dual function as a molecular-genetic sensor/reporter and a cell suicide-inducing transgene. We observed specific and simultaneous PET imaging and treatment of tumors in this preclinical model of AVPC. Our findings demonstrate the feasibility of GPR78-targeting, ligand-directed theranostics for translational applications in AVPC.

Reduced-representation Phosphosignatures Measured by Quantitative Targeted MS Capture Cellular States and Enable Large-scale Comparison of Drug-induced Phenotypes.

Profiling post-translational modifications represents an alternative dimension to gene expression data in characterizing cellular processes. Many cellular responses to drugs are mediated by changes in cellular phosphosignaling. We sought to develop a common platform on which phosphosignaling responses could be profiled across thousands of samples, and created a targeted MS assay that profiles a reduced-representation set of phosphopeptides that we show to be strong indicators of responses to chemical perturbagens.To develop the assay, we investigated the coordinate regulation of phosphosites in samples derived from three cell lines treated with 26 different bioactive small molecules. Phosphopeptide analytes were selected from these discovery studies by clustering and picking 1 to 2 proxy members from each cluster. A quantitative, targeted parallel reaction monitoring assay was developed to directly measure 96 reduced-representation probes. Sample processing for proteolytic digestion, protein quantification, peptide desalting, and phosphopeptide enrichment have been fully automated, making possible the simultaneous processing of 96 samples in only 3 days, with a plate phosphopeptide enrichment variance of 12%. This highly reproducible process allowed ∼95% of the reduced-representation phosphopeptide probes to be detected in ∼200 samples.The performance of the assay was evaluated by measuring the probes in new samples generated under treatment conditions from discovery experiments, recapitulating the observations of deeper experiments using a fraction of the analytical effort. We measured these probes in new experiments varying the treatments, cell types, and timepoints to demonstrate generalizability. We demonstrated that the assay is sensitive to disruptions in common signaling pathways (e.g. MAPK, PI3K/mTOR, and CDK). The high-throughput, reduced-representation phosphoproteomics assay provides a platform for the comparison of perturbations across a range of biological conditions, suitable for profiling thousands of samples. We believe the assay will prove highly useful for classification of known and novel drug and genetic mechanisms through comparison of phosphoproteomic signatures.

Glycosphingolipids are modulators of disease pathogenesis in amyotrophic lateral sclerosis.

Recent genetic evidence suggests that aberrant glycosphingolipid metabolism plays an important role in several neuromuscular diseases including hereditary spastic paraplegia, hereditary sensory neuropathy type 1, and non-5q spinal muscular atrophy. Here, we investigated whether altered glycosphingolipid metabolism is a modulator of disease course in amyotrophic lateral sclerosis (ALS). Levels of ceramide, glucosylceramide, galactocerebroside, lactosylceramide, globotriaosylceramide, and the gangliosides GM3 and GM1 were significantly elevated in spinal cords of ALS patients. Moreover, enzyme activities (glucocerebrosidase-1, glucocerebrosidase-2, hexosaminidase, galactosylceramidase, α-galactosidase, and ß-galactosidase) mediating glycosphingolipid hydrolysis were also elevated up to threefold. Increased ceramide, glucosylceramide, GM3, and hexosaminidase activity were also found in SOD1(G93A) mice, a familial model of ALS. Inhibition of glucosylceramide synthesis accelerated disease course in SOD1(G93A) mice, whereas infusion of exogenous GM3 significantly slowed the onset of paralysis and increased survival. Our results suggest that glycosphingolipids are likely important participants in pathogenesis of ALS and merit further analysis as potential drug targets.

Discovery and horizontal follow-up of an autoantibody signature in human prostate cancer.

In response to an urgent need for improved diagnostic and predictive serum biomarkers for management of metastatic prostate cancer, we used phage display fingerprinting to analyze sequentially acquired serum samples from a patient with advancing prostate cancer. We identified a peptide ligand, CTFAGSSC, demonstrating an increased recovery frequency over time. Serum antibody reactivity to this peptide epitope increased in the index patient, in parallel with development of deteriorating symptoms. The antigen mimicking the peptide epitope was identified as alpha-2-Heremans-Schmid glycoprotein, also known as fetuin-A. Metastatic prostate cancer cell lines and bone metastasis samples displayed robust fetuin-A expression, and we demonstrated serum immune reactivity to fetuin-A with concomitant development of metastatic castrate-resistant disease in a large cohort of prostate cancer patients. Whereas fetuin-A is an established tumor antigen in several types of cancer, including breast cancer, glioblastoma, and pancreas cancer, this report is to our knowledge the first study implicating fetuin-A in prostate cancer and indicating that autoantibodies specific for fetuin-A show utility as a prognostic indicator for prostate cancer patients prone to progress to metastatic disease.