In vivo tumor growth inhibition and biodistribution studies of locked nucleic acid (LNA) antisense oligonucleotides

Abstract

Locked nucleic acids (LNA) are novel high-affinity DNA analogs that can be used as genotype-specific drugs. The LNA oligonucleotides (LNA PO ODNs) are very stable in vitro and in vivo without the need for a phosphorothiolated backbone. In this study we tested the biological fate and the efficacy in tumor growth inhibition of antisense oligonucleotides directed against the gene of the large subunit of RNA polymerase II (POLR2A) that are completely synthesized as LNA containing diester backbones. These full LNA oligonucleotides strongly reduce POLR2A protein levels. Full LNA PO ODNs appeared to be very stable compounds when injected into the circulation of mice. Full LNA PO ODNs were continuously administered for 14 days to tumor-bearing nude mice. Tumor growth was inhibited sequence specifically at dosages from 1 mg/kg/day. LNA PO ODNs appeared to be non-toxic at dosages <5 mg/kg/day. Biodistribution studies showed the kidneys to have the highest uptake of LNA PO ODNs and urinary secretion as the major route of clearance. This report shows that LNA PO ODNs are potent genotype-specific drugs that can inhibit tumor growth in vivo.

Evaluation of locked nucleic acid–modified small interfering RNAin vitroandin vivo

“…Systemic delivery via tail vein injections of siRNA designed against POLR2A, a target previously shown suitable for tumor growth inhibition using antisense oligonucleotides (14), resulted in tumor growth inhibition.…”

“…Application of Unmodified and LNA-Modified siRNA In vivo S.c. tumors were induced in 8-to 10-week-old NMRI nu/ nu mice (Charles River, Maastricht, the Netherlands) as described previously (14). One week after tumor cell injection, when tumor take was positive, administration of the siRNA or LNA-modified siRNA started.…”

“…LNA induce an increase in thermal stability (melting temperature, T m ) when bound to a matching RNA sequence. Introduction of LNA into classic antisense oligonucleotides has been shown to increase its serum stability (14). In analogy, Braasch et al (8) showed that LNA can be used to thermally stabilize siRNAs without losing their function.…”

Anti-miRNA oligonucleotides (AMOs): ammunition to target miRNAs implicated in human disease?

“…LNA oligonucleotides have not been tested in humans, but results in rodents are promising. 74 LNAs were stable and showed a serum decay and tissue distribution similar to that of phosphorothioate oligonucleotides. A fully complementary LNA oligonucleotide targeted to murine POLR2A protein was effective using continuous administration at 2.5 mg/kg with no associated liver or kidney toxicity.…”

Comparative analysis of antisense oligonucleotide analogs for targeted DMD exon 46 skipping in muscle cells

“…Furthermore, full-length LNAs seem to hybridize in a less sequence-specific manner than PNA and 2OMePS AONs. 29,31 LNAs are negatively charged and cationic lipid polymers are applied for delivery into cells. LNAs have been shown to be potent inhibitors of the expression of a cancer-related gene, 31 but have not earlier been studied as splicing modulators.…”