Heparan sulfate proteoglycan receptor syndecan-1 interacts with the carboxyl-terminal LG4/5 domain in laminin 332 (alpha3LG4/5) and participates in cell adhesion and spreading. To dissect the function of syndecan-1 in these processes, we made use of a cell adhesion model in which syndecan-1 exclusively interacts with a recombinantly expressed alpha3LG4/5 fragment. Plating HT1080 cells on this fragment induces the formation of actin-containing protrusive structures in an integrin-independent manner. Here we show that syndecan-1-mediated formation of membrane protrusions requires dephosphorylation of tyrosine residues in syndecan-1. Accordingly, inhibition of phosphatases with orthovanadate decreases cell adhesion to the alpha3LG4/5 fragment. We demonstrate that the PDZ-containing protein syntenin-1, known to connect cytoskeletal proteins, binds to syndecan-1 in cells plated on the alpha3LG4/5 fragment and participates in the formation of membrane protrusions. We further show that syntenin-1 recruitment depends on the dephosphorylation of Tyr-309 located within syndecan-1 PDZ binding domain EFYA. We propose that tyrosine dephosphorylation of syndecan-1 may regulate its association with cytoskeleton components.

In this report, we present a novel histone deacetylase inhibitor (HDACi) (N-Hydroxy-6-(5-nitro-naphtalimide)-hexanamide: ES8) that efficiently inhibits angiogenesis in relevant ex vivo models (Human umbilical vein endothelial cells (HUVEC), 3D aortic ring assay) and in vivo (chick chorioallantoic membrane (CAM), Zebrafish). Transcriptomic profiling reveals a set of ES8 specific genes that are not affected by the prototypical HDACi suberoylanilide hydroxamic acid (SAHA). Finally, ES8 also reduced tumor growth in mouse models of small cell lung cancer. Availability of a novel compound not centered exclusively on inhibition of angiogenic factors and inducing a characteristic transcription profile may be of interest to overcome resistance to currently used chemotherapies.Citation: Shiva Shankar TV, Sulka B, Hubert P, Hubaux R, Delvenne P, et al. N-Hydroxy-6-(5-Nitro-Naphtalimide)-Hexanamide Inhibits Lysine Deacetylation, Mitigates Angiogenesis and Reduces Tumor Growth. J Cancer Sci. 2015;2(1): 11.J Cancer Sci 2(1): 11 (2015) Page -02 ISSN: 2377-9292 HDACi that potently inhibits angiogenesis and that induces a unique transcriptional profile not shared by two other reference inhibitors.