ABSTRACT
In this communication we report that anchoring αvß3 or α5ß1 integrin-selective RGD peptidomimetics to titanium efficiently tunes mesenchymal stem cell response in vitro and bone growth in rat calvarial defects. Our results demonstrate that this molecular chemistry-derived approach could be successful to engineer instructive coatings for orthopedic applications.
Subject(s)
Biocompatible Materials/pharmacology , Bone and Bones/drug effects , Mesenchymal Stem Cells/drug effects , Oligopeptides/pharmacology , Peptidomimetics/pharmacology , Animals , Biocompatible Materials/chemical synthesis , Biocompatible Materials/chemistry , Bone Regeneration/drug effects , Integrin alpha5beta1/chemistry , Integrin alphaVbeta3/chemistry , Ligands , Molecular Structure , Oligopeptides/chemical synthesis , Oligopeptides/chemistry , Peptidomimetics/chemistry , Rats , Titanium/chemistry , Titanium/pharmacology , Wound Healing/drug effectsABSTRACT
Integrin α5ß1 expression is correlated with a worse prognosis in high-grade glioma. We previously unraveled a negative crosstalk between integrin α5ß1 and p53 pathway, which was proposed to be part of the resistance of glioblastoma to chemotherapies. The restoration of p53 tumor-suppressor function is under intensive investigations for cancer therapy. However, p53-dependent apoptosis is not always achieved by p53-reactivating compounds such as Nutlin-3a, although full transcriptional activity of p53 could be obtained. Here we investigated whether integrin α5ß1 functional inhibition or repression could sensitize glioma cells to Nutlin-3a-induced p53-dependent apoptosis. We discovered that α5ß1 integrin-specific blocking antibodies or small RGD-like antagonists in association with Nutlin-3a triggered a caspase (Casp) 8/Casp 3-dependent strong apoptosis in glioma cells expressing a functional p53. We deciphered the molecular mechanisms involved and we showed the crucial role of two anti-apoptotic proteins, phosphoprotein enriched in astrocytes 15 (PEA-15) and survivin in glioma cell apoptotic outcome. PEA-15 is under α5ß1 integrin/AKT (protein kinase B) control and survivin is a p53-repressed target. Moreover, interconnections between integrin and p53 pathways were revealed. Indeed PEA-15 repression by specific small-interfering RNA (siRNA)-activated p53 pathway to repress survivin and conversely survivin repression by specific siRNA decreased α5ß1 integrin expression. This pro-apoptotic loop could be generalized to several glioma cell lines, whatever their p53 status, inasmuch PEA-15 and survivin protein levels were decreased. Our findings identify a novel mechanism whereby inhibition of α5ß1 integrin and activation of p53 modulates two anti-apoptotic proteins crucially involved in the apoptotic answer of glioma cells. Importantly, our results suggest that high-grade glioma expressing high level of α5ß1 integrin may benefit from associated therapies including integrin antagonists and repressors of survivin expression.
