High-Throughput Screening of Epigenetic Inhibitors in Meningiomas Identifies HDAC, G9a, and Jumonji-Domain Inhibition as Potential Therapies.

Background Epigenetics may predict treatment sensitivity and clinical course for patients with meningiomas more accurately than histopathology. Nonetheless, targeting epigenetic mechanisms is understudied for pharmacotherapeutic development for these tumors. The bio-molecular insights and potential therapeutic development of meningioma epigenetics led us to investigate epigenetic inhibition in meningiomas. Methods We screened a 43-tumor cohort using a 139-compound epigenetic inhibitor library to assess sensitivity of relevant meningioma subgroups to epigenetic inhibition. The cohort was composed of 5 cell lines and 38 tumors cultured directly from surgery; mean patient age was 56.6 years ± 13.9 standard deviation. Tumor categories: 38 primary tumors, 5 recurrent; 33 from females, 10 from males; 32 = grade 1; 10 = grade 2; 1 = grade 3. Results Consistent with our previous results, histone deacetylase inhibitors (HDACi) were the most efficacious class. Panobinostat significantly reduced cell viability in 36 of 43 tumors; 41 tumors had significant sensitivity to some HDACi. G9a inhibition and Jumonji-domain inhibition also significantly reduced cell viability across the cohort; tumors that lost sensitivity to panobinostat maintained sensitivity to either G9a or Jumonji-domain inhibition. Sensitivity to G9a and HDAC inhibition increased with tumor grade; tumor responses did not separate by gender. Few differences were found between recurrent and primary tumors, or between those with prior radiation versus those without. Conclusions Few efforts have investigated the efficacy of targeting epigenetic mechanisms to treat meningiomas, making the clinical utility of epigenetic inhibition largely unknown. Our results suggest that epigenetic inhibition is a targetable area for meningioma pharmacotherapy.

An extensive ß1-adrenergic receptor gene signaling network regulates molecular remodeling in dilated cardiomyopathies.

We investigated the extent, biologic characterization, phenotypic specificity, and possible regulation of a ß1-adrenergic receptor-linked (ß1-AR-linked) gene signaling network (ß1-GSN) involved in left ventricular (LV) eccentric pathologic remodeling. A 430-member ß1-GSN was identified by mRNA expression in transgenic mice overexpressing human ß1-ARs or from literature curation, which exhibited opposite directional behavior in interventricular septum endomyocardial biopsies taken from patients with beta-blocker-treated, reverse remodeled dilated cardiomyopathies. With reverse remodeling, the major biologic categories and percentage of the dominant directional change were as follows: metabolic (19.3%, 81% upregulated); gene regulation (14.9%, 78% upregulated); extracellular matrix/fibrosis (9.1%, 92% downregulated); and cell homeostasis (13.3%, 60% upregulated). Regarding the comparison of ß1-GSN categories with expression from 19,243 nonnetwork genes, phenotypic selection for major ß1-GSN categories was exhibited for LV end systolic volume (contractility measure), ejection fraction (remodeling index), and pulmonary wedge pressure (wall tension surrogate), beginning at 3 months and persisting to study completion at 12 months. In addition, 121 lncRNAs were identified as possibly involved in cis-acting regulation of ß1-GSN members. We conclude that an extensive 430-member gene network downstream from the ß1-AR is involved in pathologic ventricular remodeling, with metabolic genes as the most prevalent category.

Transition from Transient DNA Rereplication to Inherited Gene Amplification Following Prolonged Environmental Stress.

Cells require the ability to adapt to changing environmental conditions, however, it is unclear how these changes elicit stable permanent changes in genomes. We demonstrate that, in response to environmental metal exposure, the metallothionein (MT) locus undergoes DNA rereplication generating transient site-specific gene amplifications (TSSGs). Chronic metal exposure allows transition from MT TSSG to inherited MT gene amplification through homologous recombination within and outside of the MT locus. DNA rereplication of the MT locus is suppressed by H3K27me3 and EZH2. Long-term ablation of EZH2 activity eventually leads to integration and inheritance of MT gene amplifications without the selective pressure of metal exposure. The rereplication and inheritance of MT gene amplification is an evolutionarily conserved response to environmental metal from yeast to human. Our results describe a new paradigm for adaptation to environmental stress where targeted, transient DNA rereplication precedes stable inherited gene amplification.

Extrachromosomal Circular DNA from TCGA Tumors Is Generated from Common Genomic Loci, Is Characterized by Self-Homology and DNA Motifs near Circle Breakpoints.

Extrachromosomal circular DNA has emerged as a frequent genomic alteration in tumors. High numbers of circular DNAs correspond to poor prognosis suggesting an important function in tumor biology. However, despite mounting evidence supporting the importance of circular DNA, little is known about their production, maintenance, or selection. To provide insight into these processes, we analyzed circular DNA elements computationally identified in 355 TCGA tumors spanning 22 tumor types. Circular DNAs originated from common genomic loci irrespective of cancer type. Genes found in circularized genomic regions were more likely to be expressed and were enriched in cancer-related pathways. Finally, in support of a model for circle generation through either a homology or microhomology-mediated process, circles exhibit homology near their breakpoint. These breakpoints are also enriched in specific DNA motifs. Our analysis supports a model where gene-containing circles emerge from common, highly transcribed regions through a homology-mediated process.

Targeting DNA Methyl Transferases with Decitabine in Cultured Meningiomas.

OBJECTIVE: Meningiomas are a common primary central nervous system tumor that lack a U.S. Food and Drug Administration-approved pharmacotherapy. Approximately 20%-35% of meningiomas are classified as higher grade with poor outcome, whereas patients with lower-grade meningiomas are known to have long-term neurologic deficits and reduced overall survival. Recent efforts to understand the epigenetic landscape of meningiomas have highlighted the importance of DNA methylation for predicting tumor outcomes and prognosis; therefore, inhibition of these pathways may present a viable therapy for these tumors. METHODS: In this study, we perform dose-response curves of decitabine, a DNA methyltransferase inhibitor, on patient-cultured tumors and meningioma cell lines. RESULTS: Thirty total samples were evaluated, including 24 patient-cultured tumors and 6 established meningioma cell lines. Meningiomas were found to have a significant reduction in cell viability after decitabine treatment in a dose dependent manner. The effect was primarily driven by 11 of the 30 tumors in our cohort, or 36.7%. Decitabine significantly reduced cell viability across all grades, tumors from different sexes, recurrent and primary tumors, as well as tumors without a history of previous radiation. Surprisingly, our single radiation-induced tumor did demonstrate greater viability after decitabine treatment. CONCLUSIONS: Our work has identified a potential drug candidate in decitabine for the treatment of meningiomas regardless of clinical subgroup. These data require further evaluation in preclinical models, and the conclusions based on clinical subgroups need to be evaluated in a larger cohort to achieve appropriate statistical power.

Matrix-Degrading Enzyme Expression and Aortic Fibrosis During Continuous-Flow Left Ventricular Mechanical Support.

BACKGROUND: The effects of nonphysiological flow generated by continuous-flow (CF) left ventricular assist devices (LVADs) on the aorta remain poorly understood. OBJECTIVES: The authors sought to quantify indexes of fibrosis and determine the molecular signature of post-CF-LVAD vascular remodeling. METHODS: Paired aortic tissue was collected at CF-LVAD implant and subsequently at transplant from 22 patients. Aortic wall morphometry and fibrillar collagen content (a measure of fibrosis) was quantified. In addition, whole-transcriptome profiling by RNA sequencing and follow-up immunohistochemistry were performed to evaluate CF-LVAD-mediated changes in aortic mRNA and protein expression. RESULTS: The mean age was 52 ± 12 years, with a mean duration of CF-LVAD of 224 ± 193 days (range 45-798 days). There was a significant increase in the thickness of the collagen-rich adventitial layer from 218 ± 110 µm pre-LVAD to 410 ± 209 µm post-LVAD (P < 0.01). Furthermore, there was an increase in intimal and medial mean fibrillar collagen intensity from 22 ± 11 a.u. pre-LVAD to 41 ± 24 a.u. post-LVAD (P < 0.0001). The magnitude of this increase in fibrosis was greater among patients with longer durations of CF-LVAD support. CF-LVAD led to profound down-regulation in expression of extracellular matrix-degrading enzymes, such as matrix metalloproteinase-19 and ADAMTS4, whereas no evidence of fibroblast activation was noted. CONCLUSIONS: There is aortic remodeling and fibrosis after CF-LVAD that correlates with the duration of support. This fibrosis is due, at least in part, to suppression of extracellular matrix-degrading enzyme expression. Further research is needed to examine the contribution of nonphysiological flow patterns on vascular function and whether modulation of pulsatility may improve vascular remodeling and long-term outcomes.

Cytokine-Laden Extracellular Vesicles Predict Patient Prognosis after Cerebrovascular Accident.

BACKGROUND: A major contributor to disability after hemorrhagic stroke is secondary brain damage induced by the inflammatory response. Following stroke, global increases in numerous cytokines-many associated with worse outcomes-occur within the brain, cerebrospinal fluid, and peripheral blood. Extracellular vesicles (EVs) may traffic inflammatory cytokines from damaged tissue within the brain, as well as peripheral sources, across the blood-brain barrier, and they may be a critical component of post-stroke neuroinflammatory signaling. METHODS: We performed a comprehensive analysis of cytokine concentrations bound to plasma EV surfaces and/or sequestered within the vesicles themselves. These concentrations were correlated to patient acute neurological condition by the Glasgow Coma Scale (GCS) and to chronic, long-term outcome via the Glasgow Outcome Scale-Extended (GOS-E). RESULTS: Pro-inflammatory cytokines detected from plasma EVs were correlated to worse outcomes in hemorrhagic stroke patients. Anti-inflammatory cytokines detected within EVs were still correlated to poor outcomes despite their putative neuroprotective properties. Inflammatory cytokines macrophage-derived chemokine (MDC/CCL2), colony stimulating factor 1 (CSF1), interleukin 7 (IL7), and monokine induced by gamma interferon (MIG/CXCL9) were significantly correlated to both negative GCS and GOS-E when bound to plasma EV membranes. CONCLUSIONS: These findings correlate plasma-derived EV cytokine content with detrimental outcomes after stroke, highlighting the potential for EVs to provide cytokines with a means of long-range delivery of inflammatory signals that perpetuate neuroinflammation after stroke, thus hindering recovery.

High-Throughput Mechanistic Screening of Epigenetic Compounds for the Potential Treatment of Meningiomas.

BACKGROUND: Meningiomas are the most common primary central nervous system tumors. 20-30% of these tumors are considered high-grade and associated with poor prognosis and high recurrence rates. Despite the high occurrence of meningiomas, there are no FDA-approved compounds for the treatment of these tumors. METHODS: In this study, we screened patient-cultured meningiomas with an epigenetic compound library to identify targetable mechanisms for the potential treatment of these tumors. Meningioma cell cultures were generated directly from surgically resected patient tumors and were cultured on a neural matrix. Cells were treated with a library of compounds meant to target epigenetic functions. RESULTS: Although each tumor displayed a unique compound sensitivity profile, Panobinostat, LAQ824, and HC toxin were broadly effective across most tumors. These three compounds are broad-spectrum Histone Deacetylase (HDAC) inhibitors which target class I, IIa, and IIb HDACs. Panobinostat was identified as the most broadly effective compound, capable of significantly decreasing the average cell viability of the sample cohort, regardless of tumor grade, recurrence, radiation, and patient gender. CONCLUSIONS: These findings strongly suggest an important role of HDACs in meningioma biology and as a targetable mechanism. Additional validation studies are necessary to confirm these promising findings, as well to identify an ideal HDAC inhibitor candidate to develop for clinical use.

The right ventricular fibroblast secretome drives cardiomyocyte dedifferentiation.

RATIONALE: In virtually all models of heart failure, prognosis is determined by right ventricular (RV) function; thus, understanding the cellular mechanisms contributing to RV dysfunction is critical. Whole organ remodeling is associated with cell-specific changes, including cardiomyocyte dedifferentiation and activation of cardiac fibroblasts (Cfib) which in turn is linked to disorganization of cytoskeletal proteins and loss of sarcomeric structures. However, how these cellular changes contribute to RV function remains unknown. We've previously shown significant organ-level RV dysfunction in a large animal model of pulmonary hypertension (PH) which was not mirrored by reduced function of isolated cardiomyocytes. We hypothesized that factors produced by the endogenous Cfib contribute to global RV dysfunction by generating a heterogeneous cellular environment populated by dedifferentiated cells. OBJECTIVE: To determine the effect of Cfib conditioned media (CM) from the PH calf (PH-CM) on adult rat ventricular myocytes (ARVM) in culture. METHODS AND RESULTS: Brief exposure (<2 days) to PH-CM results in rapid, marked dedifferentiation of ARVM to a neonatal-like phenotype exhibiting spontaneous contractile behavior. Dedifferentiated cells maintain viability for over 30 days with continued expression of cardiomyocyte proteins including TnI and α-actinin yet exhibit myofibroblast characteristics including expression of α-smooth muscle actin. Using a bioinformatics approach to identify factor(s) that contribute to dedifferentiation, we found activation of the PH Cfib results in a unique transcriptome correlating with factors both in the secretome and with activated pathways in the dedifferentiated myocyte. Further, we identified upregulation of periostin in the Cfib and CM, and demonstrate that periostin is sufficient to drive cardiomyocyte dedifferentiation. CONCLUSIONS: These data suggest that paracrine factor(s) released by Cfib from the PH calf signal a phenotypic transformation in a population of cardiomyocytes that likely contributes to RV dysfunction. Therapies targeting this process, such as inhibition of periostin, have the potential to prevent RV dysfunction.

HDAC5 catalytic activity suppresses cardiomyocyte oxidative stress and NRF2 target gene expression.

Histone deacetylase 5 (HDAC5) and HDAC9 are class IIa HDACs that function as signal-responsive repressors of the epigenetic program for pathological cardiomyocyte hypertrophy. The conserved deacetylase domains of HDAC5 and HDAC9 are not required for inhibition of cardiac hypertrophy. Thus, the biological function of class IIa HDAC catalytic activity in the heart remains unknown. Here we demonstrate that catalytic activity of HDAC5, but not HDAC9, suppresses mitochondrial reactive oxygen species generation and subsequent induction of NF-E2-related factor 2 (NRF2)-dependent antioxidant gene expression in cardiomyocytes. Treatment of cardiomyocytes with TMP195 or TMP269, which are selective class IIa HDAC inhibitors, or shRNA-mediated knockdown of HDAC5 but not HDAC9 leads to stimulation of NRF2-mediated transcription in a reactive oxygen species-dependent manner. Conversely, ectopic expression of catalytically active HDAC5 decreases cardiomyocyte oxidative stress and represses NRF2 activation. These findings establish a role of the catalytic domain of HDAC5 in the control of cardiomyocyte redox homeostasis and define TMP195 and TMP269 as a novel class of NRF2 activators that function by suppressing the enzymatic activity of an epigenetic regulator.

Nanotopographic cues and stiffness control of tendon-derived stem cells from diverse conditions.

BACKGROUND: Tendon-derived stem cells (TDSCs) are key factors associated with regeneration and healing in tendinopathy. The aim of this study was to investigate the effects of mechanical stiffness and topographic signals on the differentiation of TDSCs depending on age and pathological conditions. MATERIALS AND METHODS: We compared TDSCs extracted from normal tendon tissues with TDSCs from tendinopathic Achilles tendon tissues of Sprague Dawley rats in vitro and TDSCs cultured on nanotopographic cues and substrate stiffness to determine how to control the TDSCs. The tendinopathy model was created using a chemical induction method, and the tendon injury model was created via an injury-and-overuse method. Norland Optical Adhesive 86 (NOA86) substrate with 2.48 GPa stiffness with and without 800 nm-wide nanogrooves and a polyurethane substrate with 800 nm-wide nanogrooves were used. RESULTS: TDSCs from 5-week-old normal tendon showed high expression of type III collagen on the flat NOA86 substrate. In the 15-week normal tendon model, expression of type III collagen was high in TDSCs cultured on the 800 nm NOA86 substrates. However, in the 15-week tendon injury model, expression of type III collagen was similar irrespective of nanotopographic cues or substrate stiffness. The expression of type I collagen was also independent of nanotopographic cues and substrate stiffness in the 15-week normal and tendon injury models. Gene expression of scleraxis was increased in TDSCs cultured on the flat NOA86 substrate in the 5-week normal tendon model (P=0.001). In the 15-week normal tendon model, scleraxis was highly expressed in TDSCs cultured on the 800 nm and flat NOA86 substrate (P=0.043). However, this gene expression was not significantly different between the substrates in the 5-week tendinopathy and 15-week tendon injury models. CONCLUSION: Development and maturation of tendon are enhanced when TDSCs from normal tendons were cultured on stiff surface, but not when the TDSCs came from pathologic models. Therapeutic applications of TDSCs need to be flexible based on tendon age and tendinopathy.

Individual probe based confocal laser endomicroscopy criteria in the analysis of indeterminate biliary strictures.

OBJECTIVES: Evaluation of indeterminate biliary strictures remains challenging due to limited sensitivity of endoscopic tissue sampling. Biliary probe-based confocal laser endomicroscopy (pCLE) has shown promise to detect and exclude neoplasia. However, knowledge of whether individual inflammatory criteria are more prevalent in neoplasia compared to benign strictures is limited. The objective of this work is to improve diagnosis of neoplastic and inflammatory conditions using pCLE. MATERIALS AND METHODS: The charts of all patients who underwent pCLE at a single referral center between 2009 and 2015 were reviewed. ERCP reports were reviewed for eleven Miami and Paris criteria. Primary outcome was the identification of neoplasia by histopathology (defined as high-grade dysplasia and/or adenocarcinoma). To model predictors of neoplasia, we fit a binary regression model incorporating data from pCLE operating criteria, pCLE impression, and PSC status. RESULTS: 97 patients were identified. In the 27 patients with neoplasia, there was increasing number of Miami malignant criteria (Pearson r = 0.512, p < .001) while inflammatory criteria were less prevalent. 10% (5/51, p < .001) of patients with benign pCLE impression developed neoplasia, while 48% (22/46, p < .001) with suspicious pCLE impressions developed neoplasia. The binary regression model to predict neoplasia had a sensitivity of 83.3%, specificity of 92.5%, and overall accuracy 89.7%. CONCLUSIONS: Presence of malignant criteria and absence of certain inflammatory criteria are more prevalent in patients with neoplasia. Our model, which weights individual imaging components, shows impressive sensitivity and specificity over prior prognostic efforts. Prospective studies will be required to evaluate this model.

Increased Incidence of Pseudoaneurysm Bleeding With Lumen-Apposing Metal Stents Compared to Double-Pigtail Plastic Stents in Patients With Peripancreatic Fluid Collections.

BACKGROUND & AIMS: There have been few studies that compared the effects of lumen-apposing metal stents (LAMS) and double-pigtail plastic stents (DPS) in patients with peripancreatic fluid collections from pancreatitis. We aimed to compare technical and clinical success and adverse events in patients who received LAMS vs DPS for pancreatic pseudocysts and walled-off necrosis. METHODS: We performed a retrospective study of endoscopic ultrasound-mediated drainage in 149 patients (65% male; mean age, 47 y) with pancreatic pseudocysts or walled-off necrosis (97 received LAMS and 152 received DPS), from January 2011 through September 2016 at a single center. We collected data on patient characteristics, outcomes, hospitalizations, and imaging findings. Technical success was defined as LAMS insertion or a minimum of 2 DPS. Clinical success was defined as resolution of pancreatic pseudocysts or walled-off necrosis based on imaging results. The primary outcome was resolution of peripancreatic fluid collection with reduced abdominal pain or obstructive signs or symptoms. Secondary outcomes included the identification and management of adverse events, number of additional procedures required to resolve fluid collection, and the recurrence of fluid collection. RESULTS: Patients who received LAMS had larger peripancreatic fluid collections than patients who received DPS prior to intervention (P = .001), and underwent an average 1.7 interventions vs 1.9 interventions for patients who received DPS (P = .93). Technical success was achieved for 90 patients with LAMS (92.8%) vs 137 patients with DPS (90.1%) (odds ratio [OR] for success with DPS, 0.82; 95% CI, 0.33-2.0; P = .67). Despite larger fluid collections in the LAMS group, there was no significant difference in proportions of patients with clinical success following placement of LAMS (82 of 84 patients, 97.6%) vs DPS (118 of 122 patients, 96.7%) (OR for clinical success with DPS, 0.73; 95% CI, 0.13-4.0; P = .71). Adverse events developed in 24 patients who received LAMS (24.7%) vs 27 patients who received DPS (17.8%) (OR for an adverse event in a patient receiving a DPS, 0.82; 95% CI, 0.33-2.0; P = .67). However, patients with LAMS had a higher risk of pseudoaneurysm bleeding than patients with DPS (OR, 10.0; 95% CI, 1.19-84.6; P = .009). CONCLUSIONS: In a retrospective study of patients undergoing drainage of pancreatic pseudocysts or walled-off necrosis, we found LAMS and DPS to have comparable rates of technical and clinical success and adverse events. Drainage of walled-off necrosis or pancreatic pseudocysts using DPS was associated with fewer bleeding events overall, including pseudoaneurysm bleeding, but bleeding risk with LAMS should be weighed against the trend of higher actionable perforation and infection rates with DPS.

Comparative Proteomic Profiling Using Two-Dimensional Gel Electrophoresis and Identification via LC-MS/MS Reveals Novel Protein Biomarkers to Identify Aggressive Subtypes of WHO Grade I Meningioma.

Background Meningomas represent the most common primary intracranial tumor. The majority are benign World Health Organization (WHO) Grade I lesions, but a subset of these behave in an aggressive manner. Protein biomarkers are needed to distinguish aggressive from benign Grade I lesions. Materials and Methods Pooled protein lysates were derived from five clinically aggressive Grade I and five typically benign WHO Grade I tumors snap frozen at the time of surgery. Proteins were separated in each group using two-dimensional gel electrophoresis (2DGE) and protein spots of interest were identified using liquid chromatography-mass spectrometry (LC-MS). Potential biomarker candidates were validated using western blot assays in individual tumor samples and by tissue microarray (TMA). Results Seven candidate biomarkers were obtained from the 2DGE and validated via western blot and TMA. Biomarker validation data allowed for the creation of predictive models using binary logistical regression that correctly identified 85.9% of aggressive tumors within the larger cohort of Grade I meningioma. Conclusion Simple protein separation by 2DGE and identification of candidate biomarkers by LC-MS allowed for the identification of seven candidate biomarkers that when used in predictive models accurately distinguish aggressive from benign behavior in WHO Grade I meningioma.

Class I HDACs control a JIP1-dependent pathway for kinesin-microtubule binding in cardiomyocytes.

Class I histone deacetylase (HDAC) inhibitors block hypertrophy and fibrosis of the heart by suppressing pathological signaling and gene expression programs in cardiac myocytes and fibroblasts. The impact of HDAC inhibition in unstressed cardiac cells remains poorly understood. Here, we demonstrate that treatment of cultured cardiomyocytes with small molecule HDAC inhibitors leads to dramatic induction of c-Jun amino-terminal kinase (JNK)-interacting protein-1 (JIP1) mRNA and protein expression. In contrast to prior findings, elevated levels of endogenous JIP1 in cardiomyocytes failed to significantly alter JNK signaling or cardiomyocyte hypertrophy. Instead, HDAC inhibitor-mediated induction of JIP1 was required to stimulate expression of the kinesin heavy chain family member, KIF5A. We provide evidence for an HDAC-dependent regulatory circuit that promotes formation of JIP1:KIF5A:microtubule complexes that regulate intracellular transport of cargo such as autophagosomes. These findings define a novel role for class I HDACs in the control of the JIP1/kinesin axis in cardiomyocytes, and suggest that HDAC inhibitors could be used to alter microtubule transport in the heart.

Pediatric dilated cardiomyopathy hearts display a unique gene expression profile.

Our previous work showed myocellular differences in pediatric and adult dilated cardiomyopathy (DCM). However, a thorough characterization of the molecular pathways involved in pediatric DCM does not exist, limiting the development of age-specific therapies. To characterize this patient population, we investigated the transcriptome profile of pediatric patients. RNA-Seq from 7 DCM and 7 nonfailing (NF) explanted age-matched pediatric left ventricles (LV) was performed. Changes in gene expression were confirmed by real-time PCR (RT-PCR) in 36 DCM and 21 NF pediatric hearts and in 20 DCM and 10 NF adult hearts. The degree of myocyte hypertrophy was investigated in 4 DCM and 7 NF pediatric hearts and in 4 DCM and 9 NF adult hearts. Changes in gene expression in response to pluripotency-inducing factors were investigated in neonatal rat ventricular myocytes (NRVMs). Transcriptome analysis identified a gene expression profile in children compared with adults with DCM. Additionally, myocyte hypertrophy was not observed in pediatric hearts but was present in adult hearts. Furthermore, treatment of NRVMs with pluripotency-inducing factors recapitulated changes in gene expression observed in the pediatric DCM heart. Pediatric DCM is characterized by unique changes in gene expression that suggest maintenance of an undifferentiated state.

Kinase Activity in Recurring Primary Skull Base Chordomas and Chondrosarcomas: Identification of Novel Pathways of Oncogenesis and Potential Drug Targets.

BACKGROUND: Chordomas and chondrosarcomas can occur in the skull base. Currently, 45% of chordomas and 56% of chondrosarcomas recur within 5 years of surgery. The role of adjuvant therapy is highly debated. No pharmacotherapies have been approved by the U.S. Food and Drug Administration for chordomas or chondrosarcomas. High propensity for recurrence and lack of definitive adjuvant therapy necessitate additional basic science research to identify molecular anomalies associated with recurrent disease. METHODS: We pooled tumor lysates from patients based on clinical criteria into 4 groups: primary chordomas, primary chordomas that recurred, primary chondrosarcomas, and primary chondrosarcomas that recurred. We used a peptide labeling method, isobaric tags for relative and absolute quantitation, to uniquely identify each tumor group. Phosphorylated peptides were identified and quantified via mass spectroscopy to determine and predict active kinases. RESULTS: Six groups of phosphorylated peptides were associated with primary tumors that later recurred. Specific kinases associated with primary chordomas that recurred were FES and FER. Specific kinases associated with primary chondrosarcomas that recurred were FES, FER, SRC family kinases, PKC, ROCK, and mitogen-activated protein kinase signaling (JNK, ERK1, p38). CONCLUSIONS: These data provide clinicians with a means to screen skull base chordomas and chondrosarcomas to help identify tumors with a propensity to recur. Many of these kinases can be efficaciously inhibited by Food and Drug Administration-approved drugs that have not yet been used in clinical trials for treatment of skull base chordomas or chondrosarcomas. Validation of kinases identified in this study may advance treatment options for patients with these tumors.

Signal-Dependent Recruitment of BRD4 to Cardiomyocyte Super-Enhancers Is Suppressed by a MicroRNA.

BRD4 governs pathological cardiac gene expression by binding acetylated chromatin, resulting in enhanced RNA polymerase II (Pol II) phosphorylation and transcription elongation. Here, we describe a signal-dependent mechanism for the regulation of BRD4 in cardiomyocytes. BRD4 expression is suppressed by microRNA-9 (miR-9), which targets the 3' UTR of the Brd4 transcript. In response to stress stimuli, miR-9 is downregulated, leading to derepression of BRD4 and enrichment of BRD4 at long-range super-enhancers (SEs) associated with pathological cardiac genes. A miR-9 mimic represses stimulus-dependent targeting of BRD4 to SEs and blunts Pol II phosphorylation at proximal transcription start sites, without affecting BRD4 binding to SEs that control constitutively expressed cardiac genes. These findings suggest that dynamic enrichment of BRD4 at SEs genome-wide serves a crucial role in the control of stress-induced cardiac gene expression and define a miR-dependent signaling mechanism for the regulation of chromatin state and Pol II phosphorylation.

Self-assembling peptides for stem cell and tissue engineering.

Regenerative medicine holds great potential to address many shortcomings in current medical therapies. An emerging avenue of regenerative medicine is the use of self-assembling peptides (SAP) in conjunction with stem cells to improve the repair of damaged tissues. The specific peptide sequence, mechanical properties, and nanotopographical cues vary widely between different SAPs, many of which have been used for the regeneration of similar tissues. To evaluate the potential of SAPs to guide stem cell fate, we extensively reviewed the literature for reports of SAPs and stem cell differentiation. To portray the most accurate summary of these studies, we deliberately discuss both the successes and pitfalls, allowing us to make conclusions that span the breadth of this exciting field. We also expand on these conclusions by relating these findings to the fields of nanotopography, mechanotransduction, and the native composition of the extracellular matrix in specific tissues to identify potential directions for future research.