A transferrin receptor 1-targeted PNA-peptide conjugate inhibits microRNA-21 expression in cardiac and other mouse tissues

MicroRNAs (miRNAs) are implicated in the onset and progression of a variety of diseases. Modulating the expression of specific miRNAs is a possible option for therapeutic intervention. A promising strategy is the use of antisense oligonucleotides (ASOs) to inhibit miRNAs. Targeting ASOs to specific tissues can potentially lower the dosage and improve clinical outcomes by alleviating systemic toxicity. We leverage here automated peptide nucleic acid (PNA) synthesis technology to manufacture an anti-miRNA oligonucleotide (antagomir) covalently attached to a 12-mer peptide that binds to transferrin receptor 1. Our PNA-peptide conjugate is active in cells and animals, effectively inhibiting the expression of miRNA-21 both in cultured mouse cardiomyocytes and different mouse organs (heart, liver, kidney, lung, and spleen), while remaining well-tolerated in animals up to the highest tested dose of 30 mg/kg. Conjugating the targeting ligand to the PNA antagomir significantly improved inhibition of miRNA-21 in the heart by over 50% relative to the PNA alone. Given the modulation of biodistribution observed with our PNA-peptide conjugate, we anticipate this antagomir platform to serve as a starting point for pre-clinical development studies. Table of Contents Entry O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/536802v1_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@645857org.highwire.dtl.DTLVardef@1e3be1corg.highwire.dtl.DTLVardef@d6286aorg.highwire.dtl.DTLVardef@1f76032_HPS_FORMAT_FIGEXP M_FIG C_FIG SynopsisConjugating T12, a peptide targeting transferrin receptor 1 (TfR1), to a peptide nucleic acid (PNA) oligonucleotide targeting microRNA-21 increases delivery of the PNA-T12 conjugate to cardiac tissue relative to PNA alone.