Superior vena cava syndrome (SVCS) is a relatively common sequela of mediastinal malignancies and may cause significant patient distress. SVCS is a medical emergency if associated with laryngeal or cerebral edema. The etiologies and management of SVCS have evolved over time. Non-malignant SVCS is typically caused by infectious etiologies or by thrombus in the superior vena cava and can be managed with antibiotics or anti-coagulation therapy, respectively. Radiation therapy (RT) has long been a mainstay of treatment of malignant SVCS. Chemotherapy has also been used to manage SVCS. In the past 20 years, percutaneous stenting of the superior vena cava has emerged as a viable option for SVCS symptom palliation. RT and chemotherapy are still the only modalities that can provide curative treatment for underlying malignant etiologies of SVCS. The first experiences with treating SVCS with RT were reported in the 1970’s, and several advances in RT delivery have subsequently occurred. Hypo-fractionated RT has the potential to be a more convenient therapy for patients and may provide equal or superior control of underlying malignancies. RT may be combined with stenting and/or chemotherapy to provide both immediate symptom palliation and long-term disease control. Clinicians should tailor therapy on a case-by-case basis. Multi-disciplinary care will maximize treatment expediency and efficacy.

Purpose: Poly(ADP-ribose) polymerase-1 (PARP-1) is the founding member of a family of enzymes that catalyze the addition of ADP-ribose units to proteins that mediate DNA repair pathways. Ionizing radiation induces DNA strand breaks, suggesting that PARP-1inhibition may sensitize tumor cells to radiation. Experimental Design: We investigated the combination of PARP-1 inhibition with radiation in lung cancer models. ABT-888, a novel potent PARP-1 inhibitor, was used to explore the effects of PARP-1inhibition on irradiated tumors and tumor vasculature. Results: ABT-888 reduced clonogenic survival in H460 lung cancer cells, and inhibited DNA repair as shown by enhanced expression of DNA strand break marker histone g-H2AX. Both apoptosis and autophagy contributed to the mechanism of increased cell death. Additionally, ABT-888 increased tumor growth delay at well-tolerated doses in murine models. For a 5-fold increase in tumor volume, tumor growth delay was 1day for ABT-888 alone, 7 days for radiation alone, and 13.5 days for combination treatment. Immunohistochemical staining of tumor sections revealed an increase in terminal deoxyribonucleotide transferase^mediated nick-end labeling apoptotic staining, and a decrease in Ki-67 proliferative staining after combination treatment. Matrigel assay showed a decrease in in vitro endothelial tubule formation with ABT-888/radiation combination treatment, and von Willebrand factor staining of tumor sections revealed decreased vessel formation in vivo, suggesting that this strategy may also target tumor angiogenesis. Conclusions: We conclude that PARP-1 inhibition shows promise as an effective means of enhancing tumor sensitivity to radiation, and future clinical studies are needed to determine the potential of ABT-888 as a radiation enhancer.

Cardiac hypertrophy is characterized by both remodeling of the extracellular matrix (ECM) and hypertrophic growth of the cardiocytes. Here we show increased expression and cytoskeletal association of the ECM proteins fibronectin and vitronectin in pressureoverloaded feline myocardium. These changes are accompanied by cytoskeletal binding and phosphorylation of focal adhesion kinase (FAK) at Tyr-397 and Tyr-925, c-Src at Tyr-416, recruitment of the adapter proteins p130Cas , Shc, and Nck, and activation of the extracellular-regulated kinases ERK1/2. A synthetic peptide containing the Arg-Gly-Asp (RGD) motif of fibronectin and vitronectin was used to stimulate adult feline cardiomyocytes cultured on laminin or within a type-I collagen matrix. Whereas cardiocytes under both conditions showed RGD-stimulated ERK1/2 activation, only collagen-embedded cells exhibited cytoskeletal assembly of FAK, c-Src, Nck, and Shc. In RGD-stimulated collagenembedded cells, FAK was phosphorylated only at Tyr-397 and c-Src association occurred without Tyr-416 phosphorylation and p130Cas association. Therefore, cSrc activation is not required for its cytoskeletal binding but may be important for additional phosphorylation of FAK. Overall, our study suggests that multiple signaling pathways originate in pressure-overloaded heart following integrin engagement with ECM proteins, including focal complex formation and ERK1/2 activation, and many of these pathways can be activated in cardiomyocytes via RGD-stimulated integrin activation.Cardiovascular diseases such as hypertension, valvular defects, and myocardial infarction are often associated with the development of cardiac hypertrophy. This hypertrophy occurs in response to an increased mechanical (hemodynamic) load on the heart in the form of pressure or volume overload, which is characteristic of hypertension and valvular defects, or to a decrease in functional heart tissue as seen in myocardial infarction. The initial hypertrophic response of the heart is compensatory but frequently deteriorates into heart failure and increased morbidity/mortality (1, 2). This transition from compensation to failure occurs when further hypertrophy of the heart cannot normalize wall stress and maintain contractile function in the face of its hemodynamic load. Although mechanical load appears to directly regulate mass and associated phenotypic changes at the level of the cardiocyte (for a review see Ref.3), the mechanisms that couple load to the hypertrophic growth initiation and to the transition into heart failure have yet to be delineated. Whereas several key players including G-proteins (4), calcineurin (5, 6), mitogen-activated protein kinase (MAPK) 1 family members, namely, extracellular-regulated kinases (ERK1/2) (7) and p38 MAPK (8), as well as protein kinase C (9) and p70/85 S6 kinase (10, 11) have been implicated in the pathways that connect load to hypertrophic growth, the complexity of interaction between signaling pathways make deciphering them a difficult task in hypertrophic research.In an...

Hypertrophic cardiac growth is a major compensatory response of the heart to an increased mechanical (hemodynamic) load in the form of either pressure or volume overload. Although this response is initially compensatory, a transition from this state to failure occurs when further growth of the heart is not sufficient to normalize the wall stress and maintain contractile function (1). Therefore, a major research interest in cardiovascular disease is to understand how the increase in hemodynamic load is transmitted intracellularly for mediating hypertrophic growth. Although the mechanical load appears to directly regulate the hypertrophic growth initiation, the signaling mechanism that connects load to such growth is not well understood.A major cellular event during cardiac hypertrophy is increased protein synthesis (1-5). Enhanced protein synthesis can occur via accelerated protein translation, increased biogenesis of translational components, or both. A significant amount of mRNA of vertebrate cells possesses a unique 5Ј-terminal oligopyrimidine (5Ј-TOP) 1 sequence in the 5Ј-untranslated region (5Ј-UTR), and these mRNA species generally code for specific ribosomal proteins (6, 7). Their translation is largely controlled via phosphorylation of the 40 S ribosomal S6 protein (S6 protein) at its C terminus (8) by p70/85 S6 kinase (S6K1) (9 -12). There are two isoforms of S6K1: the 70-kDa isoform was first isolated from mouse 3T3 cells (13), and the 85-kDa isoform of this kinase was then identified (14). The p85 isoform is expressed from the same transcript as the p70 isoform through an alternative translational initiation start site, which adds a 23-amino acid nuclear localization signal to the N terminus (15,16). Therefore, the 85-kDa isoform is predominantly in the nucleus, whereas the 70-kDa isoform is present mostly in the cytoplasm. Both the S6K isoforms are collectively called p70/85S6K, p70S6K, or S6K1 and have been shown to phosphorylate the S6 protein and mediate the biogenesis of the translational components, including several of the ribosomal proteins and elongation factors (12). The p85 isoform has been shown to have additional roles in translational control, G 1 to S phase transition, and increased DNA synthesis (17). Recent studies using S6K1 knockout mice (18) demonstrate no appreciable change in S6 protein phosphorylation, 5Ј-TOP mRNA translation, or cell growth, although these mice exhibited a small mouse phenotype. These studies (18) and other independent studies (19 -21) resulted in the discovery of another S6K (S6K2), which possesses 70% homology with the p70 isoform of

BackgroundThe ST6Gal-I sialyltransferase is upregulated in numerous cancers, and high expression of this enzyme correlates with poor patient prognosis in various malignancies, including ovarian cancer. Through its sialylation of a select cohort of cell surface receptors, ST6Gal-I modulates cell signaling to promote tumor cell survival. The goal of the present study was to investigate the influence of ST6Gal-I on another important receptor that controls cancer cell behavior, EGFR. Additionally, the effect of ST6Gal-I on cancer cells treated with the common EGFR inhibitor, gefitinib, was evaluated.ResultsUsing the OV4 ovarian cancer cell line, which lacks endogenous ST6Gal-I expression, a kinomics assay revealed that cells with forced overexpression of ST6Gal-I exhibited increased global tyrosine kinase activity, a finding confirmed by immunoblotting whole cell lysates with an anti-phosphotyrosine antibody. Interestingly, the kinomics assay suggested that one of the most highly activated tyrosine kinases in ST6Gal-I-overexpressing OV4 cells was EGFR. Based on these findings, additional analyses were performed to investigate the effect of ST6Gal-I on EGFR activation. To this end, we utilized, in addition to OV4 cells, the SKOV3 ovarian cancer cell line, engineered with both ST6Gal-I overexpression and knockdown, as well as the BxPC3 pancreatic cancer cell line with knockdown of ST6Gal-I. In all three cell lines, we determined that EGFR is a substrate of ST6Gal-I, and that the sialylation status of EGFR directly correlates with ST6Gal-I expression. Cells with differential ST6Gal-I expression were subsequently evaluated for EGFR tyrosine phosphorylation. Cells with high ST6Gal-I expression were found to have elevated levels of basal and EGF-induced EGFR activation. Conversely, knockdown of ST6Gal-I greatly attenuated EGFR activation, both basally and post EGF treatment. Finally, to illustrate the functional importance of ST6Gal-I in regulating EGFR-dependent survival, cells were treated with gefitinib, an EGFR inhibitor widely used for cancer therapy. These studies showed that ST6Gal-I promotes resistance to gefitinib-mediated apoptosis, as measured by caspase activity assays.ConclusionResults herein indicate that ST6Gal-I promotes EGFR activation and protects against gefitinib-mediated cell death. Establishing the tumor-associated ST6Gal-I sialyltransferase as a regulator of EGFR provides novel insight into the role of glycosylation in growth factor signaling and chemoresistance.

Previous reports have implicated an induction of genes in IFN/STAT1 (Interferon/STAT1) signaling in radiation resistant and prosurvival tumor phenotypes in a number of cancer cell lines, and we have hypothesized that upregulation of these genes may be predictive of poor survival outcome and/or treatment response in Glioblastoma Multiforme (GBM) patients. We have developed a list of 8 genes related to IFN/STAT1 that we hypothesize to be predictive of poor survival in GBM patients. Our working hypothesis that over-expression of this gene signature predicts poor survival outcome in GBM patients was confirmed, and in addition, it was demonstrated that the survival model was highly subtype-dependent, with strong dependence in the Proneural subtype and no detected dependence in the Classical and Mesenchymal subtypes. We developed a specific multi-gene survival model for the Proneural subtype in the TCGA (the Cancer Genome Atlas) discovery set which we have validated in the TCGA validation set. In addition, we have performed network analysis in the form of Bayesian Network discovery and Ingenuity Pathway Analysis to further dissect the underlying biology of this gene signature in the etiology of GBM. We theorize that the strong predictive value of the IFN/STAT1 gene signature in the Proneural subtype may be due to chemotherapy and/or radiation resistance induced through prolonged constitutive signaling of these genes during the course of the illness. The results of this study have implications both for better prediction models for survival outcome in GBM and for improved understanding of the underlying subtype-specific molecular mechanisms for GBM tumor progression and treatment response.

Purpose This study assessed whether Myristoylated Alanine Rich C-Kinase Substrate (MARCKS) can regulate glioblastoma (GBM) growth, radiation sensitivity and clinical outcome. Experimental Design MARCKS protein levels were analyzed in five GBM explant cell lines and eight patient-derived xenograft tumors by immunoblot, and these levels were correlated to proliferation rates and intracranial growth rates, respectively. Manipulation of MARCKS protein levels was assessed by lentiviral-mediated shRNA knockdown in the U251 cell line and MARCKS over-expression in the U87 cell line. The effect of manipulation of MARCKS on proliferation, radiation sensitivity and senescence was assessed. MARCKS gene expression was correlated with survival outcomes in the Repository of Molecular Brain Neoplasia Data (REMBRANDT) Database and The Cancer Genome Atlas (TCGA). Results MARCKS protein expression was inversely correlated with GBM proliferation and intracranial xenograft growth rates. Genetic silencing of MARCKS promoted GBM proliferation and radiation resistance, while MARCKS overexpression greatly reduced GBM growth potential and induced senescence. We found MARCKS gene expression to be directly correlated with survival in both the REMBRANDT and TCGA databases. Specifically, patients with high MARCKS expressing tumors of the Proneural molecular subtype had significantly increased survival rates. This effect was most pronounced in tumors with unmethylated O6-methylguanine DNA methyltransferase (MGMT) promoters, a traditionally poor prognostic factor. Conclusions MARCKS levels impact GBM growth and radiation sensitivity. High MARCKS expressing GBM tumors are associated with improved survival, particularly with unmethylated MGMT promoters. These findings suggest the use of MARCKS as a novel target and biomarker for prognosis in the Proneural subtype of GBM.

The ability of breast cancer cells to transiently transition between epithelial and mesenchymal states contributes to their metastatic potential. Therefore, driving tumor cells into a stable mesenchymal state, as opposed to complete tumor cell eradication, presents an opportunity to pharmacologically limit disease progression by promoting an asymptomatic state of dormancy. Here, we compare a reversible model of epithelial-mesenchymal transition (EMT) induced by TGFb to a stable mesenchymal phenotype induced by chronic exposure to the ErbB kinase inhibitor lapatinib. Only cells capable of returning to an epithelial phenotype resulted in skeletal metastasis. Gene expression analyses of the two mesenchymal states indicated similar transition expression profiles. A potently downregulated gene in both datasets was spleen tyrosine kinase (SYK). In contrast to this similar diminution in mRNA, kinome analyses using a peptide array and DNA-conjugated peptide substrates showed a robust increase in SYK activity upon TGFb-induced EMT only. SYK was present in cytoplasmic RNA processing depots known as P-bodies formed during the onset of EMT, and SYK activity was required for autophagy-mediated clearance of P-bodies during mesenchymal-epithelial transition (MET). Genetic knockout of autophagy-related 7 (ATG7) or pharmacologic inhibition of SYK activity with fostamatinib, a clinically approved inhibitor of SYK, prevented P-body clearance and MET, inhibiting metastatic tumor outgrowth. Overall, this study suggests assessment of SYK activity as a biomarker for metastatic disease and the use of fostamatinib as a means to stabilize the latency of disseminated tumor cells.