ABSTRACT
Despite the introduction of tyrosine kinase inhibitor therapy, the prognosis for p190-BCR-ABL(+) acute lymphoblastic leukemia remains poor. In the present study, we present the cellular and molecular roles of the Rho GTPase guanine nucleotide exchange factor Vav in lymphoid leukemogenesis and explore the roles of Vav proteins in BCR-ABL-dependent signaling. We show that genetic deficiency of the guanine nucleotide exchange factor Vav3 delays leukemogenesis by p190-BCR-ABL and phenocopies the effect of Rac2 deficiency, a downstream effector of Vav3. Compensatory up-regulation of expression and activation of Vav3 in Vav1/Vav2-deficient B-cell progenitors increases the transformation ability of p190-BCR-ABL. Vav3 deficiency induces apoptosis of murine and human leukemic lymphoid progenitors, decreases the activation of Rho GTPase family members and p21-activated kinase, and is associated with increased Bad phosphorylation and up-regulation of Bax, Bak, and Bik. Finally, Vav3 activation only partly depends on ABL TK activity, and Vav3 deficiency collaborates with tyrosine kinase inhibitors to inhibit CrkL activation and impair leukemogenesis in vitro and in vivo. We conclude that Vav3 represents a novel specific molecular leukemic effector for multitarget therapy in p190-BCR-ABL-expressing acute lymphoblastic leukemia.
Subject(s)
B-Lymphocytes/pathology , Cell Transformation, Neoplastic/pathology , Fusion Proteins, bcr-abl/metabolism , Lymphoid Progenitor Cells/pathology , Precursor Cell Lymphoblastic Leukemia-Lymphoma/pathology , Proto-Oncogene Proteins c-vav/physiology , Animals , B-Lymphocytes/metabolism , Cell Transformation, Neoplastic/metabolism , Cells, Cultured , Female , Fetal Blood/cytology , Fetal Blood/metabolism , Humans , Lymphoid Progenitor Cells/metabolism , Mice , Mice, Inbred C57BL , Mice, Knockout , Phosphorylation , Precursor Cell Lymphoblastic Leukemia-Lymphoma/metabolism , Survival Rate , Tumor Stem Cell Assay , rac GTP-Binding Proteins/physiology , RAC2 GTP-Binding ProteinABSTRACT
Cordylophora caspia, a colonial hydrozoan native to the Ponto-Caspian region, has become a common invader of both fresh and brackish water ecosystems of North America and Europe. We describe 11 polymorphic microsatellite loci for this species. Preliminary analyses indicate that population substructure may contribute to departures from Hardy-Weinberg equilibrium. In addition, new loci failed to consistently amplify Cordylophora samples known to be genetically distant from those utilized in this study, indicating the presence of cryptic diversity within the taxon.
