Head-to-head comparison of in vitro and in vivo efficacy of pHLIP-conjugated anti-seed gamma peptide nucleic acids

Gamma peptide nucleic acids (yPNAs) have recently garnered atten-tion in diverse therapeutic and diagnostic applications. Serine and diethylene-glycol-containing yPNAs have been tested for numerous RNA-targeting purposes. Here, we comprehensively evaluated the in vitro and in vivo efficacy of pH-low insertion peptide (pHLIP)-con-jugated serine and diethylene-based yPNAs. pHLIP targets only the acidic tumor microenvironment and not the normal cells. We synthe-sized and parallelly tested pHLIP-serine yPNAs and pHLIP-diethy-lene glycol yPNAs that target the seed region of microRNA-155, a microRNA that is upregulated in various cancers. We performed an all-atom molecular dynamics simulation-based computational study to elucidate the interaction of pHLIP-yPNA constructs with the lipid bilayer. We also determined the biodistribution and effi-cacy of the pHLIP constructs in the U2932-derived xenograft model. Overall, we established that the pHLIP-serine yPNAs show superior results in vivo compared with the pHLIP-diethylene glycol-based yPNA.