ABSTRACT
Sema3C protein, a member of the class 3 family of secreted semaphorins, play an important role in tumor development by regulating cell proliferation, migration, invasion, and angiogenesis processes. Depending on the type and malignancy grade of the tumor, Sema3C function remains controversial. In this study, we constructed a stably overexpressing Sema3C glioblastoma cell line U87 MG and tested it on the chicken embryo chorioallantoic membrane (CAM) model with the aim to reveal Sema3C protein function on angiogenesis process in ovo. Our experiments showed that Sema3C not only affects angiogenesis of CAM by inhibiting neovascularization but also acts as an anti-tumorigenic molecule by hampering U87 MG cell invasion into mesenchyme. The effects of Sema3C on CAM were similar to the effects of anti-epileptic drug sodium valproate (NaVP). Both, anti-angiogenic and anti-tumorigenic activities of Sema3C were enhanced by the treatment of NaVP and, importantly, were not attributed to the cytotoxic effects. Our studies suggest that Sema3C could be a promising target for glioblastoma treatment.
Subject(s)
Glioblastoma/metabolism , Neoplasms, Experimental/metabolism , Neovascularization, Pathologic/metabolism , Semaphorins/metabolism , Tumor Suppressor Proteins/metabolism , Animals , Cell Line, Tumor , Chick Embryo , Chorioallantoic Membrane/metabolism , Chorioallantoic Membrane/pathology , Glioblastoma/drug therapy , Glioblastoma/genetics , Glioblastoma/pathology , Humans , Neoplasm Invasiveness , Neoplasms, Experimental/drug therapy , Neoplasms, Experimental/genetics , Neoplasms, Experimental/pathology , Neovascularization, Pathologic/drug therapy , Neovascularization, Pathologic/genetics , Neovascularization, Pathologic/pathology , Semaphorins/genetics , Tumor Suppressor Proteins/genetics , Valproic Acid/pharmacologyABSTRACT
We previously identified talin rod domain-containing protein 1 (TLNRD1) as a potent actin-bundling protein in vitro. Here, we report that TLNRD1 is expressed in the vasculature in vivo. Its depletion leads to vascular abnormalities in vivo and modulation of endothelial cell monolayer integrity in vitro. We demonstrate that TLNRD1 is a component of the cerebral cavernous malformations (CCM) complex through its direct interaction with CCM2, which is mediated by a hydrophobic C-terminal helix in CCM2 that attaches to a hydrophobic groove on the four-helix domain of TLNRD1. Disruption of this binding interface leads to CCM2 and TLNRD1 accumulation in the nucleus and actin fibers. Our findings indicate that CCM2 controls TLNRD1 localization to the cytoplasm and inhibits its actin-bundling activity and that the CCM2-TLNRD1 interaction impacts endothelial actin stress fiber and focal adhesion formation. Based on these results, we propose a new pathway by which the CCM complex modulates the actin cytoskeleton and vascular integrity.