title: c-Abl mediates endothelial apoptosis induced by inhibition of integrins alphavbeta3 and alphavbeta5 and by disruption of actin.
abstract: Inhibition of integrins alphavbeta3 and alphavbeta5 in human brain microvascular endothelial cells (HBMECs) by the function-blocking peptide RGDfV induces loss of spreading on vitronectin, cell detachment, and apoptosis. We demonstrate that cell detachment is not required for apoptosis because plating on bovine serum albumin-blocked poly-L-lysine (allows attachment, but not integrin ligation and cell spreading) also induced apoptosis. Latrunculin B (LatB), which inhibits F-actin polymerization, induced transient loss of HBMEC spreading on vitronectin, but not their detachment, and induced apoptosis despite recovery of cell spreading. However, LatB did not cause apoptosis in 5 tumor cell lines. In HBMECs, both LatB and RGDfV induced transient Y412 and Y245 phosphorylation of endogenous c-Abl, a nonreceptor tyrosine kinase that reciprocally regulates F-actin. LatB also induced nuclear translocation of c-Abl in HBMECs. STI-571 (imatinib), a targeted therapy for BCR-ABL1(+) leukemias and inhibitor of c-Abl, platelet-derived growth factor receptor, and c-Kit, decreased endothelial apoptosis. LatB-induced HBMEC apoptosis, and its inhibition by STI-571 also occurred in a 3-dimensional collagen model, supporting physiologic relevance. Last, siRNA to c-Abl (but not nonspecific siRNA) also inhibited RGDfV- and LatB-induced apoptosis. Thus, endogenous c-Abl mediates endothelial apoptosis induced by inhibition of integrins alphavbeta3/alphavbeta5 or by LatB-induced disruption of F-actin.
authors.affiliation: Department of Pediatrics, Neil Bogart Memorial Laboratories, Division of Hematology-Oncology, Saban Research Institute at Childrens Hospital Los Angeles, USA.
authors.forename: Jingying
authors.initials: J
authors.lastname: Xu
authors.forename: Melissa
authors.initials: M
authors.lastname: Millard
authors.forename: Xiuhai
authors.initials: X
authors.lastname: Ren
authors.forename: Orla T
authors.initials: OT
authors.lastname: Cox
authors.forename: Anat
authors.initials: A
authors.lastname: Erdreich-Epstein
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects / Q000648:ultrastructure; D000199:Actins / Q000037:antagonists & inhibitors*; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002417:Cattle; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D048430:Cell Shape / Q000187:drug effects; D003470:Culture Media / Q000494:pharmacology; D016895:Culture Media, Serum-Free; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects; D005312:Fetal Blood; D016313:Genes, abl; D005909:Glioblastoma / Q000473:pathology; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000037:antagonists & inhibitors*; D008527:Medulloblastoma / Q000473:pathology; D053078:Membrane Potential, Mitochondrial; D009447:Neuroblastoma / Q000473:pathology; D016315:Proto-Oncogene Proteins c-abl / Q000037:antagonists & inhibitors / Q000502:physiology*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D019030:Receptors, Vitronectin / Q000037:antagonists & inhibitors*; D053778:Thiazolidines / Q000494:pharmacology
chemical_list: D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D003470:Culture Media; D016895:Culture Media, Serum-Free; D039302:Integrin alphaVbeta3; D034741:RNA, Small Interfering; D019030:Receptors, Vitronectin; D053778:Thiazolidines; C064660:integrin alphaVbeta5; D016315:Proto-Oncogene Proteins c-abl; C037068:latrunculin B