Strategies for oligoribonucleotide synthesis according to the phosphoramidite method.

Advances in oligoribonucleotide synthesis have lagged behind those in oligodeoxyribonucleotide synthesis because of the difficulty in identifying orthogonal protecting groups for the 2'- and 5'-hydroxyls. Adaptation of the phosphoramidite method for DNA synthesis to RNA synthesis has greatly improved our understanding of RNA. It allows site-specific introduction of modified nucleosides to any position in an RNA molecule, as well as introduction of variations at multiple sites in the molecule.

Elucidation of the initial step of oligonucleotide fragmentation in matrix-assisted laser desorption/ionization using modified nucleic acids.

To probe the mechanism of gas-phase oligonucleotide ion fragmentation, modified oligonucleotides were studied using matrix-assisted laser desorption/ionization. The oligonucleotides were of the form 5'-TTTTXTTTTT, where X was a modified nucleotide. Modifications included substitution of hydroxy, methoxy, amino, and allyl groups at the 2'-position of the deoxyribose.

X-ray crystallographic observation of "in-line" and "adjacent" conformations in a bulged self-cleaving RNA/DNA hybrid.

The RNA strand in an RNA/DNA duplex with unpaired ribonucleotides can undergo self-cleavage at bulge sites in the presence of a variety of divalent metal ions (Hüsken et al., Biochemistry, 1996, 35:16591-16600). Transesterification proceeds via an in-line mechanism, with the 2'-OH of the bulged nucleotide attacking the 3'-adjacent phosphate group.

Antitumor and antimetastatic activity of ribozymes targeting the messenger RNA of vascular endothelial growth factor receptors.

Chemically stabilized hammerhead ribozymes are nuclease-resistant, RNA-based oligonucleotides that selectively bind and cleave specific target RNAs. Due to their potential for specifically inhibiting gene expression, ribozymes are being investigated for therapeutic applications as well as for the elucidation of gene function. In particular, we have investigated ribozymes that target the mRNA of the vascular endothelial growth factor (VEGF) receptors because VEGF signaling is an important mediator of tumor angiogenesis and metastasis.

Pharmacokinetics of an antiangiogenic ribozyme (ANGIOZYME) in the mouse.

Vascular endothelial growth factor (VEGF) is a growth factor that contributes to the angiogenesis of developing tumors. To interfere with the action of VEGF, a nuclease-stabilized ribozyme, ANGIOZYME, has been developed against VEGF receptor subtype Flt-1 mRNA. To determine which routes of administration would be useful for systemic delivery of this ribozyme, a dose of 30 mg/kg [32P]ANGIOZYME was administered as an i.