FGF2 Binding, Signaling, Angiogenesis Are Modulated by Heparanase in Metastatic Melanoma Cells

Heparanase (HPSE) and fibroblast growth factor-2 (FGF2) are critical regulators of melanoma angiogenesis and metastasis. Elevated HPSE expression contributes to melanoma progression; however, further augmentation of HPSE presence can inhibit tumorigenicity. HPSE enzymatically cleaves heparan sulfate glycosaminoglycan chains (HS) from proteoglycans. HS act as both low-affinity FGF2 receptors and coreceptors in the formation of high-affinity FGF2 receptors. We have investigated HPSE's ability to modulate FGF2 activity through HS remodeling. Extensive HPSE degradation of human metastatic melanoma cells (70W) inhibited FGF2 binding. Unexpectedly, treatment of 70W cells with low HPSE concentrations enhanced FGF2 binding. In addition, HPSE-unexposed cells did not phosphorylate extracellular signal-related kinase (ERK) or focal adhesion kinase (FAK) in response to FGF2. Conversely, in cells treated with HPSE, FGF2 stimulated ERK and FAK phosphorylation. Secondly, the presence of soluble HPSE-degraded HS enhanced FGF2 binding and ERK phosphorylation at low HS concentrations. Higher concentrations of soluble HS inhibited FGF2 binding, but FGF2 signaling through ERK remained enhanced. Soluble HS were unable to support FGF2-stimulated FAK phosphorylation irrespective of HPSE treatment. Finally, cell exposure to HPSE or to HPSE-degraded HS modulated FGF2induced angiogenesis in melanoma. In conclusion, these effects suggest relevant mechanisms for the HPSE modulation of melanoma growth factor responsiveness and tumorigenicity

Notum deacylates Wnt proteins to suppress signalling activity

Signalling by Wnt proteins is finely balanced to ensure normal development and tissue homeostasis while avoiding diseases such as cancer. This is achieved in part by Notum, a highly conserved secreted feedback antagonist. Notum has been thought to act as a phospholipase, shedding glypicans and associated Wnt proteins from the cell surface. However, this view fails to explain specificity, as glypicans bind many extracellular ligands. Here we provide genetic evidence in Drosophila that Notum requires glypicans to suppress Wnt signalling, but does not cleave their glycophosphatidylinositol anchor. Structural analyses reveal glycosaminoglycan binding sites on Notum, which probably help Notum to co-localize with Wnt proteins. They also identify, at the active site of human and Drosophila Notum, a large hydrophobic pocket that accommodates palmitoleate. Kinetic and mass spectrometric analyses of human proteins show that Notum is a carboxylesterase that removes an essential palmitoleate moiety from Wnt proteins and thus constitutes the first known extracellular protein deacylase

Ticagrelor Monotherapy or Dual Antiplatelet Therapy After Drug‐Eluting Stent Implantation: Per‐Protocol Analysis of the GLOBAL LEADERS Trial

International audienceBackground In the GLOBAL LEADERS trial, ticagrelor monotherapy beyond 1 month compared with standard antiplatelet regimens after coronary stent implantation did not improve outcomes at intention‐to‐treat analysis. Considerable differences in treatment adherence between the experimental and control groups may have affected the intention‐to‐treat results. In this reanalysis of the GLOBAL LEADERS trial, we compared the experimental and control treatment strategies in a per‐protocol analysis of patients who did not deviate from the study protocol. Methods and Results Baseline and postrandomization information were used to classify whether and when patients were deviating from the study protocol. With logistic regressions, we derived time‐varying inverse probabilities of nondeviation from protocol to reconstruct the trial population without protocol deviation. The primary end point was a composite of all‐cause mortality or nonfatal Q‐wave myocardial infarction at 2 years. At 2‐year follow‐up, 1103 (13.8%) of 7980 patients in the experimental group and 785 (9.8%) of 7988 patients in the control group qualified as protocol deviators. At per‐protocol analysis, the rate ratio for the primary end point was 0.88 (95% CI, 0.75–1.03; P =0.10) on the basis of 274 versus 325 events in the experimental versus control group. The rate ratio for the key safety end point of major bleeding was 1.00 (95% CI, 0.79–1.26; P =0.99). The per‐protocol and intention‐to‐treat effect estimates were overall consistent. Conclusions Among patients who complied with the study protocol in the GLOBAL LEADERS trial, ticagrelor plus aspirin for 1 month followed by ticagrelor monotherapy was not superior to 1‐year standard dual antiplatelet therapy followed by aspirin alone at 2 years after coronary stenting. Registration URL: https://www.clinicaltrials.gov ; Unique identifier: NCT01813435