Enhancing RNA inhibitory activity using clamp-G-modified nucleobases.

We explore the potential of clamp-G nucleobase-modified peptide nucleic acids (cGPNAs) as microRNA and messenger RNA inhibitors. For proof of concept, we target miR-155, which is upregulated in diffuse large B cell lymphoma. cGPNA shows significant downregulation of miR-155 and the upregulation of its downstream targets in multiple lymphoma cell lines. Also, cGPNA treatment in vivo reduced tumor growth and improved survival in the U2932 cell-derived xenograft mouse model. To assess the broad application of cGPNA as an antisense modality, we also target transthyretin (TTR) mRNA. We establish a dose-dependent effect of antisense cGPNA on TTR mRNA levels. For in vivo studies, we conjugated cGPNA-based TTR antisense with lactobionic acid-based targeting ligand for in vivo liver delivery. We establish that cGPNA exhibits significant TTR protein knockdown compared to unmodified peptide nucleic acid (PNA) in vivo. Overall, we confirm that clamp-G-modified PNA analogs are a robust antisense therapy platform.