query: p16INK4A accumulation is  linked to an abnormal wound response caused by the microinvasive step of advanced Oral Potentially Malignant Lesions (OPMLs).

positive: Monitoring Tumorigenesis and Senescence In Vivo with a p16INK4a-Luciferase Model Monitoring cancer and aging in vivo remains experimentally challenging. Here, we describe a luciferase knockin mouse (p16(LUC)), which faithfully reports expression of p16(INK4a), a tumor suppressor and aging biomarker. Lifelong assessment of luminescence in p16(+/LUC) mice revealed an exponential increase with aging, which was highly variable in a cohort of contemporaneously housed, syngeneic mice. Expression of p16(INK4a) with aging did not predict cancer development, suggesting that the accumulation of senescent cells is not a principal determinant of cancer-related death. In 14 of 14 tested tumor models, expression of p16(LUC) was focally activated by early neoplastic events, enabling visualization of tumors with sensitivity exceeding other imaging modalities. Activation of p16(INK4a) was noted in the emerging neoplasm and surrounding stromal cells. This work suggests that p16(INK4a) activation is a characteristic of all emerging cancers, making the p16(LUC) allele a sensitive, unbiased reporter of neoplastic transformation.

negative: Gene expression analysis by cDNA microarray in oral squamous cell carcinoma. BACKGROUND Oral squamous cell carcinoma (OSCC) is common type of human cancer, but little is known about the molecular mechanisms deciding on this malignancy. Comprehensive gene expression profiling is essential for understanding OSCC. METHODS cDNA microarray was used to analyze expression patterns of 16 617 genes in nine OSCC patients. RESULTS Forty-seven genes with altered expression among all cases were extracted. The ontology of these 47 genes was classified into 10 categories. To validate the microarray data, the expression of genes, including TGFBI, FADD and DUSP1 was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR). By hierarchical clustering analysis, the nine cases were divided into two clusters. CONCLUSIONS The 47 genes are suggested as having a functional significance in oral squamous cell carcinogenesis. It is also suggested that the gene expression patterns by hierarchical clustering analysis can represent degrees of differentiation. The postoperative recovery was uneventful and patients free from tumor after surgery. In the future, on the occasion when the time comes that the number of cases accumulated for microarray increases and each case is observed more over a long-term, these data of 5-year survival rate will be added. Thereby, it will become possible to represent the malignancy of OSCC by these gene expression patterns.

negative: Histone tails: Directing the chromatin response to DNA damage. Considerable energetic investment is devoted to altering large stretches of chromatin adjacent to DNA double strand breaks (DSBs). Immediately ensuing DSB formation, a myriad of histone modifications are elicited to create a platform for inducible and modular assembly of DNA repair protein complexes in the vicinity of the DNA lesion. This complex signaling network is critical to repair DNA damage and communicate with cellular processes that occur in cis and in trans to the genomic lesion. Failure to properly execute DNA damage inducible chromatin changes is associated with developmental abnormalities, immunodeficiency, and malignancy in humans and in genetically engineered mouse models. This review will discuss current knowledge of DNA damage responsive histone changes that occur in mammalian cells, highlighting their involvement in the maintenance of genome integrity.

negative: Senescent growth arrest in mesenchymal stem cells is bypassed by Wip1-mediated downregulation of intrinsic stress signaling pathways. Human mesenchymal stem cells (hMSCs) have been widely studied as a source of primary adult stem cells for cell therapy because of their multidifferentiation potential; however, the growth arrest (also known as "premature senescence") often found in hMSCs cultured in vitro has been a major obstacle to the in-depth characterization of these cells. In addition, the inability to maintain constant cell growth hampers the development of additional genetic modifications aimed at achieving desired levels of differentiation to specific tissues; however, the molecular mechanisms that govern this phenomenon remain unclear, with the exception of a few studies demonstrating that induction of p16INK4a is responsible for this senescence-like event. Here, we observed that the premature growth arrest in hMSCs occurs in parallel with the induction of p16INK4a, following abrogation of inhibitory phosphorylation of retinoblastoma protein. These stress responses were concurrent with increased formation of reactive oxygen species (ROSs) from mitochondria and increased p38 mitogen-activated protein kinase (MAPK) activity. The introduction of Wip1 (wild-type p53 inducible phosphatase-1), a well-studied stress modulator, significantly lowered p16INK4a expression and led to p38 MAPK inactivation, although it failed to affect the levels of ROSs. Moreover, the suppression of stress responses by Wip1 apparently extended the life span of hMSCs, compared with control conditions, while maintaining their multilineage differentiation potential. Based on these results, we suggest that senescent growth arrest in hMSCs may result from activation of stress signaling pathways and consequent onset of stress responses, due in part to ROS production during prolonged in vitro culture.

negative: Oral ciclopirox olamine displays biological activity in a phase I study in patients with advanced hematologic malignancies. The antimycotic ciclopirox olamine is an intracellular iron chelator that has anticancer activity in vitro and in vivo. We developed an oral formulation of ciclopirox olamine and conducted the first-in-human phase I study of this drug in patients with relapsed or refractory hematologic malignancies (Trial registration ID: NCT00990587). Patients were treated with 5-80 mg/m² oral ciclopirox olamine once daily for five days in 21-day treatment cycles. Pharmacokinetic and pharmacodynamic companion studies were performed in a subset of patients. Following definition of the half-life of ciclopirox olamine, an additional cohort was enrolled and treated with 80 mg/m² ciclopirox olamine four times daily. Adverse events and clinical response were monitored throughout the trial. Twenty-three patients received study treatment. Ciclopirox was rapidly absorbed and cleared with a short half-life. Plasma concentrations of an inactive ciclopirox glucuronide metabolite were greater than those of ciclopirox. Repression of survivin expression was observed in peripheral blood cells isolated from patients treated once daily with ciclopirox olamine at doses greater than 10 mg/m², demonstrating biological activity of the drug. Dose-limiting gastrointestinal toxicities were observed in patients receiving 80 mg/m² four times daily, and no dose limiting toxicity was observed at 40 mg/m² once daily. Hematologic improvement was observed in two patients. Once-daily dosing of oral ciclopirox olamine was well tolerated in patients with relapsed or refractory hematologic malignancies, and further optimization of dosing regimens is warranted in this patient population.

negative: Treatment with cyclooxygenase-2 inhibitors enables repeated administration of vaccinia virus for control of ovarian cancer. Metastatic ovarian cancer is the leading cause of death among women with gynecologic malignancies in the United States. The lack of effective treatment for patients with advanced ovarian cancer warrants development of innovative therapies. Cancer therapy using oncolytic viruses represents a promising new approach for controlling tumors. Vaccinia virus has been shown to preferentially infect tumor cells but not normal tissue. However, oncolytic therapy using recombinant viruses faces the limitation of viral clearance due to generation of neutralizing antibodies. In the current study, we found that cyclooxygenase-2 (Cox-2) inhibitors circumvented this limitation, enabling repeated administration of vaccinia virus without losing infectivity. We quantified the antivaccinia antibody response using enzyme-linked immunosorbent assay (ELISA) and neutralization assays to show that treatment of Cox-2 inhibitors inhibited the generation of neutralizing antibodies. Furthermore, we showed that combination treatment of Cox-2 inhibitors with vaccinia virus was more effective that either treatment alone in treating MOSEC/luc tumor-bearing mice. Thus, the combination of Cox-2 inhibitors and vaccinia virus represents a potential innovative approach to controlling ovarian tumors.

negative: Asymptomatic spinal cord lesions predict disease progression in radiologically isolated syndrome. BACKGROUND Technological advancements in neuroimaging and the increased use of these diagnostic modalities are responsible for the discovery of incidentally identified anomalies within the CNS. In addition to the identification of unanticipated brain MRI abnormalities suggestive of demyelinating disease in patients undergoing neuroimaging for a medical reason other than evaluation for multiple sclerosis (MS), asymptomatic spinal cord lesions are periodically identified. OBJECTIVE To determine if asymptomatic spinal cord lesions are associated with clinical progression in subjects with radiologically isolated syndrome (RIS). METHODS A retrospective review of RIS cases at the University of California, San Francisco Multiple Sclerosis Center was performed. The presence of asymptomatic cervical spinal cord MRI lesions was analyzed as a potential predictor for clinical progression. RESULTS Twenty-five of 71 subjects with RIS possessed findings within the cervical spine that were highly suggestive of demyelinating disease. Of these subjects, 21 (84%) progressed clinically to clinically isolated syndrome (n = 19) or primary progressive multiple sclerosis (n = 2) over a median time of 1.6 years from the date of RIS identification (interquartile range 0.8-3.8). The sensitivity, specificity, and positive predictive value of an asymptomatic spinal cord lesion for subsequent development of either a first demyelinating attack or primary progressive MS were 87.5%, 91.5%, and 84%, respectively. The odds ratio of clinical progression was 75.3 (95% confidence interval 16.1-350.0, p < 0.0001). This association remained significant after adjusting for potential confounders. CONCLUSION These findings suggest that the presence of asymptomatic spinal cord lesions place subjects with RIS at substantial risk for clinical conversion to either an acute or progressive event, a risk that is independent of brain lesions on MRI.

negative: Nuclear accumulation of HDAC4 in ATM deficiency promotes neurodegeneration in ataxia-telangiectasia Ataxia telangiectasia is a neurodegenerative disease caused by mutation of the Atm gene. Here we report that ataxia telangiectasia mutated (ATM) deficiency causes nuclear accumulation of histone deacetylase 4 (HDAC4) in neurons and promotes neurodegeneration. Nuclear HDAC4 binds to chromatin, as well as to myocyte enhancer factor 2A (MEF2A) and cAMP-responsive element binding protein (CREB), leading to histone deacetylation and altered neuronal gene expression. Blocking either HDAC4 activity or its nuclear accumulation blunts these neurodegenerative changes and rescues several behavioral abnormalities of ATM-deficient mice. Full rescue of the neurodegeneration, however, also requires the presence of HDAC4 in the cytoplasm, suggesting that the ataxia telangiectasia phenotype results both from a loss of cytoplasmic HDAC4 as well as its nuclear accumulation. To remain cytoplasmic, HDAC4 must be phosphorylated. The activity of the HDAC4 phosphatase, protein phosphatase 2A (PP2A), is downregulated by ATM-mediated phosphorylation. In ATM deficiency, enhanced PP2A activity leads to HDAC4 dephosphorylation and the nuclear accumulation of HDAC4. Our results define a crucial role of the cellular localization of HDAC4 in the events leading to ataxia telangiectasia neurodegeneration.

negative: Regulated Accumulation of Desmosterol Integrates Macrophage Lipid Metabolism and Inflammatory Responses Inflammation and macrophage foam cells are characteristic features of atherosclerotic lesions, but the mechanisms linking cholesterol accumulation to inflammation and LXR-dependent response pathways are poorly understood. To investigate this relationship, we utilized lipidomic and transcriptomic methods to evaluate the effect of diet and LDL receptor genotype on macrophage foam cell formation within the peritoneal cavities of mice. Foam cell formation was associated with significant changes in hundreds of lipid species and unexpected suppression, rather than activation, of inflammatory gene expression. We provide evidence that regulated accumulation of desmosterol underlies many of the homeostatic responses, including activation of LXR target genes, inhibition of SREBP target genes, selective reprogramming of fatty acid metabolism, and suppression of inflammatory-response genes, observed in macrophage foam cells. These observations suggest that macrophage activation in atherosclerotic lesions results from extrinsic, proinflammatory signals generated within the artery wall that suppress homeostatic and anti-inflammatory functions of desmosterol.

negative: Lessons from sudden coronary death: a comprehensive morphological classification scheme for atherosclerotic lesions. This review will reconsider the current paradigm for understanding the critical, final steps in the progression of atherosclerotic lesions. That scheme, largely an outgrowth of observations of autopsy tissues by Davies and colleagues,1 2 asserts that the cause of death in atherosclerotic coronary artery disease is rupture of an advanced atherosclerotic lesion. Although this assumption may be partially true, recent autopsy studies suggest that it is incomplete. To reconsider this paradigm, we reexamined the morphological classification scheme for lesions proposed by the American Heart Association (AHA).3 4 This scheme is difficult to use for 2 reasons. First, it uses a very long list of roman numerals modified by letter codes that are difficult to remember. Second, it implies an orderly, linear pattern of lesion progression. This tends to be ambiguous, because it is not clear whether there is a single sequence of events during the progression of all lesions. We have therefore tried to devise a simpler classification scheme that is consistent with the AHA categories but is easier to use, able to deal with a wide array of morphological variations, and not overly burdened by mechanistic implications. The current paradigm is based on the belief that type IV lesions, or “atheromas,” described by the AHA are stable because the fatty, necrotic core is contained by a smooth muscle cell–rich fibrous cap. Virchow’s analysis5 in 1858 pointed out that historically, the term “atheroma” refers to a dermal cyst (“Grutzbalg”), a fatty …

negative: A small molecule restores function to TRPML1 mutant isoforms responsible for mucolipidosis type IV. Mucolipidosis type IV (MLIV) is an autosomal recessive lysosomal storage disorder often characterized by severe neurodevelopmental abnormalities and neuro-retinal degeneration. Mutations in the TRPML1 gene are causative for MLIV. We used lead optimization strategies to identify--and MLIV patient fibroblasts to test--small-molecule activators for their potential to restore TRPML1 mutant channel function. Using the whole-lysosome planar patch-clamp technique, we found that activation of MLIV mutant isoforms by the endogenous ligand PI(3,5)P2 is strongly reduced, while activity can be increased using synthetic ligands. We also found that the F465L mutation renders TRPML1 pH insensitive, while F408Δ impacts synthetic ligand binding. Trafficking defects and accumulation of zinc in lysosomes of MLIV mutant fibroblasts can be rescued by the small molecule treatment. Collectively, our data demonstrate that small molecules can be used to restore channel function and rescue disease associated abnormalities in patient cells expressing specific MLIV point mutations.

negative: Deletion of the developmentally essential gene ATR in adult mice leads to age-related phenotypes and stem cell loss. Developmental abnormalities, cancer, and premature aging each have been linked to defects in the DNA damage response (DDR). Mutations in the ATR checkpoint regulator cause developmental defects in mice (pregastrulation lethality) and humans (Seckel syndrome). Here we show that eliminating ATR in adult mice leads to defects in tissue homeostasis and the rapid appearance of age-related phenotypes, such as hair graying, alopecia, kyphosis, osteoporosis, thymic involution, fibrosis, and other abnormalities. Histological and genetic analyses indicate that ATR deletion causes acute cellular loss in tissues in which continuous cell proliferation is required for maintenance. Importantly, thymic involution, alopecia, and hair graying in ATR knockout mice were associated with dramatic reductions in tissue-specific stem and progenitor cells and exhaustion of tissue renewal and homeostatic capacity. In aggregate, these studies suggest that reduced regenerative capacity in adults via deletion of a developmentally essential DDR gene is sufficient to cause the premature appearance of age-related phenotypes.

negative: The porphyrias: advances in diagnosis and treatment. The inborn errors of heme biosynthesis, the porphyrias, are 8 genetically distinct metabolic disorders that can be classified as "acute hepatic," "hepatic cutaneous," and "erythropoietic cutaneous" diseases. Recent advances in understanding their pathogenesis and molecular genetic heterogeneity have led to improved diagnosis and treatment. These advances include DNA-based diagnoses for all the porphyrias, new understanding of the pathogenesis of the acute hepatic porphyrias, identification of the iron overload-induced inhibitor of hepatic uroporphyrin decarboxylase activity that causes the most common porphyria, porphyria cutanea tarda, the identification of an X-linked form of erythropoietic protoporphyria due to gain-of-function mutations in erythroid-specific 5-aminolevulinate synthase (ALAS2), and new and experimental treatments for the erythropoietic porphyrias. Knowledge of these advances is relevant for hematologists because they administer the hematin infusions to treat the acute attacks in patients with the acute hepatic porphyrias, perform the chronic phlebotomies to reduce the iron overload and clear the dermatologic lesions in porphyria cutanea tarda, and diagnose and treat the erythropoietic porphyrias, including chronic erythrocyte transfusions, bone marrow or hematopoietic stem cell transplants, and experimental pharmacologic chaperone and stem cell gene therapies for congenital erythropoietic protoporphyria. These developments are reviewed to update hematologists on the latest advances in these diverse disorders.

negative: Targeting brain cancer: advances in the molecular pathology of malignant glioma and medulloblastoma Malignant brain tumours continue to be the cause of a disproportionate level of morbidity and mortality across a wide range of individuals. The most common variants in the adult and paediatric populations — malignant glioma and medulloblastoma, respectively — have been the subject of increasingly intensive research over the past two decades that has led to considerable advances in the understanding of their basic biology and pathogenesis. This Review summarizes these developments in the context of the evolving notion of molecular pathology and discusses the implications that this work has on the design of new treatment regimens.

negative: Targeted nanoparticles containing the proresolving peptide Ac2-26 protect against advanced atherosclerosis in hypercholesterolemic mice Chronic, nonresolving inflammation is a critical factor in the clinical progression of advanced atherosclerotic lesions. In the normal inflammatory response, resolution is mediated by several agonists, among which is the glucocorticoid-regulated protein called annexin A1. The proresolving actions of annexin A1, which are mediated through its receptor N-formyl peptide receptor 2 (FPR2/ALX), can be mimicked by an amino-terminal peptide encompassing amino acids 2–26 (Ac2-26). Collagen IV (Col IV)–targeted nanoparticles (NPs) containing Ac2-26 were evaluated for their therapeutic effect on chronic, advanced atherosclerosis in fat-fed Ldlr−/− mice. When administered to mice with preexisting lesions, Col IV–Ac2-26 NPs were targeted to lesions and led to a marked improvement in key advanced plaque properties, including an increase in the protective collagen layer overlying lesions (which was associated with a decrease in lesional collagenase activity), suppression of oxidative stress, and a decrease in plaque necrosis. In mice lacking FPR2/ALX in myeloid cells, these improvements were not seen. Thus, administration of a resolution-mediating peptide in a targeted NP activates its receptor on myeloid cells to stabilize advanced atherosclerotic lesions. These findings support the concept that defective inflammation resolution plays a role in advanced atherosclerosis, and suggest a new form of therapy.

negative: CpG island methylator phenotype predicts progression of malignant melanoma. PURPOSE The CpG island methylator phenotype (CIMP) may be associated with development of malignancy through coordinated inactivation of tumor suppressor and tumor-related genes (TRG) and methylation of multiple noncoding, methylated-in-tumor (MINT) loci. These epigenetic changes create a distinct CIMP pattern that has been linked to recurrence and survival in gastrointestinal cancers. Because epigenetic inactivation of TRGs also has been shown in malignant melanoma, we hypothesized the existence of a clinically significant CIMP in cutaneous melanoma progression. EXPERIMENTAL DESIGN The methylation status of the CpG island promoter region of TRGs related to melanoma pathophysiology (WIF1, TFPI2, RASSF1A, RARbeta2, SOCS1, and GATA4) and a panel of MINT loci (MINT1, MINT2, MINT3, MINT12, MINT17, MINT25, and MINT31) in primary and metastatic tumors of different clinical stages (n=122) was assessed. RESULTS Here, we show an increase in hypermethylation of the TRGs WIF1, TFPI2, RASSF1A, and SOCS1 with advancing clinical tumor stage. Furthermore, we find a significant positive association between the methylation status of MINT17, MINT31, and TRGs. The methylation status of MINT31 is associated with disease outcome in stage III melanoma. CONCLUSIONS These findings show the significance of a CIMP pattern that is associated with advancing clinical stage of malignant melanoma. Future prospective large-scale studies may determine if CIMP-positive primary melanomas are at high risk of metastasis or recurrence.

negative: Local proliferation dominates lesional macrophage accumulation in atherosclerosis During the inflammatory response that drives atherogenesis, macrophages accumulate progressively in the expanding arterial wall. The observation that circulating monocytes give rise to lesional macrophages has reinforced the concept that monocyte infiltration dictates macrophage buildup. Recent work has indicated, however, that macrophage accumulation does not depend on monocyte recruitment in some inflammatory contexts. We therefore revisited the mechanism underlying macrophage accumulation in atherosclerosis. In murine atherosclerotic lesions, we found that macrophages turn over rapidly, after 4 weeks. Replenishment of macrophages in these experimental atheromata depends predominantly on local macrophage proliferation rather than monocyte influx. The microenvironment orchestrates macrophage proliferation through the involvement of scavenger receptor A (SR-A). Our study reveals macrophage proliferation as a key event in atherosclerosis and identifies macrophage self-renewal as a therapeutic target for cardiovascular disease.

negative: Review article Ribosomopathies compose a collection of disorders in which genetic abnormalities cause impaired ribosome biogenesis and function, resulting in specific clinical phenotypes. Congenital mutations in RPS19 and other genes encoding ribosomal proteins cause Diamond-Blackfan anemia, a disorder characterized by hypoplastic, macrocytic anemia. Mutations in other genes required for normal ribosome biogenesis have been implicated in other rare congenital syndromes, Schwachman-Diamond syndrome, dyskeratosis congenita, cartilage hair hypoplasia, and Treacher Collins syndrome. In addition, the 5q- syndrome, a subtype of myelodysplastic syndrome, is caused by a somatically acquired deletion of chromosome 5q, which leads to haploinsufficiency of the ribosomal protein RPS14 and an erythroid phenotype highly similar to Diamond-Blackfan anemia. Acquired abnormalities in ribosome function have been implicated more broadly in human malignancies. The p53 pathway provides a surveillance mechanism for protein translation as well as genome integrity and is activated by defects in ribosome biogenesis; this pathway appears to be a critical mediator of many of the clinical features of ribosomopathies. Elucidation of the mechanisms whereby selective abnormalities in ribosome biogenesis cause specific clinical syndromes will hopefully lead to novel therapeutic strategies for these diseases.

negative: Interplays between ATM/Tel1 and ATR/Mec1 in sensing and signaling DNA double-strand breaks. DNA double-strand breaks (DSBs) are highly hazardous for genome integrity because they have the potential to cause mutations, chromosomal rearrangements and genomic instability. The cellular response to DSBs is orchestrated by signal transduction pathways, known as DNA damage checkpoints, which are conserved from yeasts to humans. These pathways can sense DNA damage and transduce this information to specific cellular targets, which in turn regulate cell cycle transitions and DNA repair. The mammalian protein kinases ATM and ATR, as well as their budding yeast corresponding orthologs Tel1 and Mec1, act as master regulators of the checkpoint response to DSBs. Here, we review the early steps of DSB processing and the role of DNA-end structures in activating ATM/Tel1 and ATR/Mec1 in an orderly and reciprocal manner.

negative: Advances in brain tumor surgery. Advances in the fields of molecular and translational research, oncology, and surgery have emboldened the medical community to believe that intrinsic brain tumors may be treatable. Intraoperative imaging and brain mapping allow operations adjacent to eloquent cortex and more radical resection of tumors with increased confidence and safety. Despite these advances, the infiltrating edge of a neoplasm and distant microscopic satellite lesions will never be amendable to a surgical cure. Indeed, it is continued research into the delivery of an efficacious chemobiologic agent that will eventually allows us to manage this primary cause of treatment failure.

negative: From bloodjournal.hematologylibrary.org at PENN STATE UNIVERSITY on February 23, 2013. For personal use only. Megakaryocyte (MK) is the naturally polyploid cell that gives rise to platelets. Polyploidization occurs by endomitosis, which was a process considered to be an incomplete mitosis aborted in anaphase. Here, we used time-lapse confocal video microscopy to visualize the endomitotic process of primary human megakaryocytes. Our results show that the switch from mitosis to endomitosis corresponds to a late failure of cytokinesis accompanied by a backward movement of the 2 daughter cells. No abnormality was observed in the central spindle of endomitotic MKs. A furrow formation was present, but the contractile ring was abnormal because accumulation of nonmuscle myosin IIA was lacking. In addition, a defect in cell elongation was observed in dipolar endomitotic MKs during telophase. RhoA and F-actin were partially concentrated at the site of furrowing. Inhibition of the Rho/Rock pathway caused the disappearance of F-actin at midzone and increased MK ploidy level. This inhibition was associated with a more pronounced defect in furrow formation as well as in spindle elongation. Our results suggest that the late failure of cytokinesis responsible for the endomitotic process is related to a partial defect in the Rho/Rock pathway activation.

negative: A Mechanism Linking Extra Centrosomes to Chromosomal Instability Chromosomal instability (CIN) is a hallmark of many tumours and correlates with the presence of extra centrosomes. However, a direct mechanistic link between extra centrosomes and CIN has not been established. It has been proposed that extra centrosomes generate CIN by promoting multipolar anaphase, a highly abnormal division that produces three or more aneuploid daughter cells. Here we use long-term live-cell imaging to demonstrate that cells with multiple centrosomes rarely undergo multipolar cell divisions, and the progeny of these divisions are typically inviable. Thus, multipolar divisions cannot explain observed rates of CIN. In contrast, we observe that CIN cells with extra centrosomes routinely undergo bipolar cell divisions, but display a significantly increased frequency of lagging chromosomes during anaphase. To define the mechanism underlying this mitotic defect, we generated cells that differ only in their centrosome number. We demonstrate that extra centrosomes alone are sufficient to promote chromosome missegregation during bipolar cell division. These segregation errors are a consequence of cells passing through a transient 'multipolar spindle intermediate' in which merotelic kinetochore-microtubule attachment errors accumulate before centrosome clustering and anaphase. These findings provide a direct mechanistic link between extra centrosomes and CIN, two common characteristics of solid tumours. We propose that this mechanism may be a common underlying cause of CIN in human cancer.

negative: The Hippo pathway effector YAP controls mouse hepatic stellate cell activation. BACKGROUND & AIMS Hepatic stellate cell activation is a wound-healing response to liver injury. However, continued activation of stellate cells during chronic liver damage causes excessive matrix deposition and the formation of pathological scar tissue leading to fibrosis and ultimately cirrhosis. The importance of sustained stellate cell activation for this pathological process is well recognized, and several signalling pathways that can promote stellate cell activation have been identified, such as the TGFβ-, PDGF-, and LPS-dependent pathways. However, the mechanisms that trigger and drive the early steps in activation are not well understood. METHODS AND RESULTS We identified the Hippo pathway and its effector YAP as a key pathway that controls stellate cell activation. YAP is a transcriptional co-activator and we found that it drives the earliest changes in gene expression during stellate cell activation. Activation of stellate cells in vivo by CCl4 administration to mice or activation in vitro caused rapid activation of YAP as revealed by its nuclear translocation and by the induction of YAP target genes. YAP was also activated in stellate cells of human fibrotic livers as evidenced by its nuclear localization. Importantly, knockdown of YAP expression or pharmacological inhibition of YAP prevented hepatic stellate cell activation in vitro and pharmacological inhibition of YAP impeded fibrogenesis in mice. CONCLUSIONS YAP activation is a critical driver of hepatic stellate cell activation and inhibition of YAP presents a novel approach for the treatment of liver fibrosis.

negative: Involvement of ER Stress in Dysmyelination of Pelizaeus-Merzbacher Disease with PLP1 Missense Mutations Shown by iPSC-Derived Oligodendrocytes Pelizaeus-Merzbacher disease (PMD) is a form of X-linked leukodystrophy caused by mutations in the proteolipid protein 1 (PLP1) gene. Although PLP1 proteins with missense mutations have been shown to accumulate in the rough endoplasmic reticulum (ER) in disease model animals and cell lines transfected with mutant PLP1 genes, the exact pathogenetic mechanism of PMD has not previously been clarified. In this study, we established induced pluripotent stem cells (iPSCs) from two PMD patients carrying missense mutation and differentiated them into oligodendrocytes in vitro. In the PMD iPSC-derived oligodendrocytes, mislocalization of mutant PLP1 proteins to the ER and an association between increased susceptibility to ER stress and increased numbers of apoptotic oligodendrocytes were observed. Moreover, electron microscopic analysis demonstrated drastically reduced myelin formation accompanied by abnormal ER morphology. Thus, this study demonstrates the involvement of ER stress in pathogenic dysmyelination in the oligodendrocytes of PMD patients with the PLP1 missense mutation.

negative: G-protein-coupled receptor of Kaposi's sarcoma-associated herpesvirus is a viral oncogene and angiogenesis activator. The Kaposi's sarcoma-associated herpesvirus (KSHV/HHV8) is a gamma-2 herpesvirus that is implicated in the pathogenesis of Kaposi's sarcoma and of primary effusion B-cell lymphomas (PELs). KSHV infects malignant and progenitor cells of Kaposi's sarcoma and PEL, it encodes putative oncogenes and genes that may cause Kaposi's sarcoma pathogenesis by stimulating angiogenesis. The G-protein-coupled receptor encoded by an open reading frame (ORF 74) of KSHV is expressed in Kaposi's sarcoma lesions and in PEL and stimulates signalling pathways linked to cell proliferation in a constitutive (agonist-independent) way. Here we show that signalling by this KSHV G-protein-coupled receptor leads to cell transformation and tumorigenicity, and induces a switch to an angiogenic phenotype mediated by vascular endothelial growth factor, an angiogenesis and Kaposi's-spindle-cell growth factor. We find that this receptor can activate two protein kinases, JNK/SAPK and p38MAPK, by triggering signalling cascades like those induced by inflammatory cytokines that are angiogenesis activators and mitogens for Kaposi's sarcoma cells and B cells. We conclude that the KSHV G-protein-coupled receptor is a viral oncogene that can exploit cell signalling pathways to induce transformation and angiogenesis in KSHV-mediated oncogenesis.

negative: Modulation of mitochondrial function and morphology by interaction of Omi/HtrA2 with the mitochondrial fusion factor OPA1. Loss of Omi/HtrA2 function leads to nerve cell loss in mouse models and has been linked to neurodegeneration in Parkinson's and Huntington's disease. Omi/HtrA2 is a serine protease released as a pro-apoptotic factor from the mitochondrial intermembrane space into the cytosol. Under physiological conditions, Omi/HtrA2 is thought to be involved in protection against cellular stress, but the cytological and molecular mechanisms are not clear. Omi/HtrA2 deficiency caused an accumulation of reactive oxygen species and reduced mitochondrial membrane potential. In Omi/HtrA2 knockout mouse embryonic fibroblasts, as well as in Omi/HtrA2 silenced human HeLa cells and Drosophila S2R+ cells, we found elongated mitochondria by live cell imaging. Electron microscopy confirmed the mitochondrial morphology alterations and showed abnormal cristae structure. Examining the levels of proteins involved in mitochondrial fusion, we found a selective up-regulation of more soluble OPA1 protein. Complementation of knockout cells with wild-type Omi/HtrA2 but not with the protease mutant [S306A]Omi/HtrA2 reversed the mitochondrial elongation phenotype and OPA1 alterations. Finally, co-immunoprecipitation showed direct interaction of Omi/HtrA2 with endogenous OPA1. Thus, we show for the first time a direct effect of loss of Omi/HtrA2 on mitochondrial morphology and demonstrate a novel role of this mitochondrial serine protease in the modulation of OPA1. Our results underscore a critical role of impaired mitochondrial dynamics in neurodegenerative disorders.

negative: Metabolic Reprograming in Macrophage Polarization Studying the metabolism of immune cells in recent years has emphasized the tight link existing between the metabolic state and the phenotype of these cells. Macrophages in particular are a good example of this phenomenon. Whether the macrophage obtains its energy through glycolysis or through oxidative metabolism can give rise to different phenotypes. Classically activated or M1 macrophages are key players of the first line of defense against bacterial infections and are known to obtain energy through glycolysis. Alternatively activated or M2 macrophages on the other hand are involved in tissue repair and wound healing and use oxidative metabolism to fuel their longer-term functions. Metabolic intermediates, however, are not just a source of energy but can be directly implicated in a particular macrophage phenotype. In M1 macrophages, the Krebs cycle intermediate succinate regulates HIF1α, which is responsible for driving the sustained production of the pro-inflammatory cytokine IL1β. In M2 macrophages, the sedoheptulose kinase carbohydrate kinase-like protein is critical for regulating the pentose phosphate pathway. The potential to target these events and impact on disease is an exciting prospect.

negative: Identification of splenic reservoir monocytes and their deployment to inflammatory sites. A current paradigm states that monocytes circulate freely and patrol blood vessels but differentiate irreversibly into dendritic cells (DCs) or macrophages upon tissue entry. Here we show that bona fide undifferentiated monocytes reside in the spleen and outnumber their equivalents in circulation. The reservoir monocytes assemble in clusters in the cords of the subcapsular red pulp and are distinct from macrophages and DCs. In response to ischemic myocardial injury, splenic monocytes increase their motility, exit the spleen en masse, accumulate in injured tissue, and participate in wound healing. These observations uncover a role for the spleen as a site for storage and rapid deployment of monocytes and identify splenic monocytes as a resource that the body exploits to regulate inflammation.

negative: Molecular elements of low-oxygen signaling in plants. Oxygen and its limitation are emerging as a crucial factor in plant fitness, growth and development. Recent studies revealed the mechanisms by which oxygen is perceived by plant cells. This sensory system partly relies on an oxygen-mediated branch of the N-end rule pathway for protein degradation acting on a specific clade of ethylene responsive transcription factors (ERF-VII). A complementary regulative step is provided by aerobic sequestration of an ERF-VII protein at the plasma membrane and its timely release when hypoxia occurs. Complete absence of oxygen triggers the transient accumulation of reactive hydrogen peroxide and induces an additional set of reactive oxygen species-related genes involved in both signaling and attenuation of oxidative stress. Moreover, temporary hypoxic environments that are built up as consequence of dense cell packing have been demonstrated to trigger cell-fate determination in maize anthers. Similarly, limited oxygen delivery in bulky fruit or tuber tissues growing in aerobic conditions were shown to stimulate anaerobic-like responses. These advances in low-oxygen signaling and its effect on cell development highlight the importance of taking hypoxia into account in agronomical practices as well as in breeding programs.

negative: Mechanisms of Age-Related Macular Degeneration Age-related macular degeneration (AMD), a progressive condition that is untreatable in up to 90% of patients, is a leading cause of blindness in the elderly worldwide. The two forms of AMD, wet and dry, are classified based on the presence or absence of blood vessels that have disruptively invaded the retina, respectively. A detailed understanding of the molecular mechanisms underlying wet AMD has led to several robust FDA-approved therapies. In contrast, there are no approved treatments for dry AMD. In this review, we provide insight into the critical effector pathways mediating each form of the disease. A recurring theme that spans most aspects of AMD pathogenesis is defective immune modulation in the classically immune-privileged ocular haven. Interestingly, the latest advances in AMD research also highlight common molecular disease pathways with other neurodegenerative disorders. Finally, the therapeutic potential of intervening at known mechanistic steps of AMD pathogenesis is discussed.

negative: Cell Stem Cell Review FoxO Transcription Factors and Stem Cell Homeostasis: Insights from the Hematopoietic System The forkhead O (FoxO) family of transcription factors participates in diverse physiologic processes, including induction of cell-cycle arrest, stress resistance, differentiation, apoptosis, and metabolism. Several recent studies indicate that FoxO-dependent signaling is required for long-term regenerative potential of the hematopoietic stem cell (HSC) compartment through regulation of HSC response to physiologic oxidative stress, quiescence, and survival. These observations link FoxO function in mammalian systems with the evolutionarily conserved role of FoxO in promotion of stress resistance and longevity in lower phylogenetic systems. Furthermore, these findings have implications for aging in higher organisms and in malignant stem cell biology, and suggest that FoxOs may play an important role in the maintenance and integrity of stem cell compartments in a broad spectrum of tissues.

negative: Coronary plaque disruption. Coronary atherosclerosis is by far the most frequent cause of ischemic heart disease, and plaque disruption with superimposed thrombosis is the main cause of the acute coronary syndromes of unstable angina, myocardial infarction, and sudden death.1 2 3 4 5 Therefore, for event-free survival, the vital question is not why atherosclerosis develops but rather why, after years of indolent growth, it suddenly becomes complicated by life-threatening thrombosis. The composition and vulnerability of plaque rather than its volume or the consequent severity of stenosis produced have emerged as being the most important determinants for the development of the thrombus-mediated acute coronary syndromes; lipid-rich and soft plaques are more dangerous than collagen-rich and hard plaques because they are more unstable and rupture-prone and highly thrombogenic after disruption.6 This review will explore potential mechanisms responsible for the sudden conversion of a stable atherosclerotic plaque to an unstable and life-threatening atherothrombotic lesion—an event known as plaque fissuring, rupture, or disruption.7 8   Atherosclerosis is the result of a complex interaction between blood elements, disturbed flow, and vessel wall abnormality, involving several pathological processes: inflammation, with increased endothelial permeability, endothelial activation, and monocyte recruitment9 10 11 12 13 14 ; growth, with smooth muscle cell (SMC) proliferation, migration, and matrix synthesis15 16 ; degeneration, with lipid accumulation17 18 ; necrosis, possibly related to the cytotoxic effect of oxidized lipid19 ; calcification/ossification, which may represent an active rather than a dystrophic process20 21 ; and thrombosis, with platelet recruitment and fibrin formation.1 22 23 Thrombotic factors may play a role early during atherogenesis, but a flow-limiting thrombus does not develop until mature plaques are present, which is why thrombosis often is classified as a complication rather than a genuine component of atherosclerosis. ### Mature Plaques: Atherosis and Sclerosis   As the name atherosclerosis implies, mature …

negative: Neuroinflammation in spinal cord injury: therapeutic targets for neuroprotection and regeneration. Traumatic spinal cord injury triggers a complex local inflammatory reaction capable of enhancing repair and exacerbating pathology. The composition and effector potential of the post-injury cellular and molecular immune cascade changes as a function of time and distance from the lesion. Production along this time-space continuum of cytokines, proteases, and growth factors establishes dynamic environments that lead to the death, damage, repair or growth of affected neurons and glia. Microenvironmental cues, therefore, generated by the cells therein, may determine these distinct fates of repair versus pathology. To harness repair, it is necessary to manipulate the assembly and phenotype of cells that comprise the neuroinflammatory response to injury. Here, the potential of the neuroinflammatory response to cause outcomes such as pain, regeneration, and functional recovery is reviewed.