Intra-arterial delivery of endostatin gene to brain tumors prolongs survival and alters tumor vessel ultrastructure

Glioblastoma multiforme (GBM) is an incurable malignant brain tumor, usually fatal within 1 year of diagnosis. Using a syngeneic rat 9L gliosarcoma model, we have developed a novel drug delivery method in which naked plasmid DNA is selectively targeted to brain tumors via intra-arterial injection. Using a plasmid encoding the antiangiogenic endostatin, transgene expression can be detected in tumor cells in vivo, and therapeutic efficacy is observed. Administration of this plasmid resulted in an 80% tumor volume reduction 1 week after treatment and enhanced survival time by up to 47%. Treated tumors exhibited a 40% decrease in the number of tumor vessels; ultrastructural analysis of remaining tumor vessels demonstrated a number of changes including markedly narrowed or collapsed lumens. We conclude that intra-arterial injection of plasmids selectively targets therapeutic genes to CNS neoplasms. This method of gene therapy holds promise for the treatment of these highly malignant brain tumors.

A phospholipid kinase regulates actin organization and intercellular bridge formation during germline cytokinesis

The endgame of cytokinesis can follow one of two pathways depending on developmental context: resolution into separate cells or formation of a stable intercellular bridge. Here we show that the four wheel drive (fwd) gene of Drosophila melanogaster is required for intercellular bridge formation during cytokinesis in male meiosis. In fwd mutant males, contractile rings form and constrict in dividing spermatocytes, but cleavage furrows are unstable and daughter cells fuse together, producing multinucleate spermatids. fwd is shown to encode a phosphatidylinositol 4-kinase (PI 4-kinase), a member of a family of proteins that perform the first step in the synthesis of the key regulatory membrane phospholipid PIP2. Wild-type activity of the fwd PI 4-kinase is required for tyrosine phosphorylation in the cleavage furrow and for normal organization of actin filaments in the constricting contractile ring. Our results suggest a critical role for PI 4-kinases and phosphatidylinositol derivatives during the final stages of cytokinesis.