The alpha 5 beta 1 integrin represent a new therapeutic target for glioblastoma, which are malignant brain tumors difficult to cure with conventional therapies. Glioblastoma are known to be highly resistant to chemotherapy. We, therefore, investigated whether blocking alpha 5 beta 1 integrin with specific nonpeptidic antagonists concomitantly with chemotherapy (ellipticine and temozolomide) may impact the response to chemotherapy of human glioblastoma. Here we show that inhibiting alpha 5 beta 1 integrin with 2 selective ligands (SJ749 and K34c) decreases chemotherapy-induced premature senescence and facilitates cell apoptosis in a functional p53 background (U87MG cells). When p53 is mutated and inactive (U373 cells), chemotherapy induces p53-independent cell apoptosis instead of senescence that is not improved by integrin antagonists. Silencing p53 in U87MG cells with siRNA as well as evaluating HCT116 p53+/+ and p53-/- colon carcinoma cell behavior support the hypothesis of an as yet unknown effect of alpha 5 beta 1 integrin antagonists on the control of chemotherapy-induced premature senescence and apoptosis. alpha 5 beta 1 integrin antagonists modulate the p53 signaling induced by chemotherapy. Our results highlight a new rote of the alpha 5 beta 1 integrin in the control of glioblastoma aggressiveness and responsiveness to chemotherapy, which may have a crucial impact in the clinical management of patients suffering from brain tumors.
