Comparison of Drug Delivery Efficiency between Doxorubicin Intercalated in RNA Aptamer and One Encapsulated in RNA Aptamer-Conjugated Liposome

Combination of drug delivery and specific targeting has the potential for treating cancers. To achieve this goal, specific ligands targeting cancer cells and bioconjugate vehicles for drug delivery are necessary. Liposomes constitute successful drug-delivery materials because they can reduce toxicity and enhance the stability of drugs by encapsulation. Previously, we have developed an RNA aptamer-conjugated liposome (named as aptamosome) that specifically targeted prostate cancer cells expressing prostate-specific membrane antigen (PSMA). Using the aptamosome, the anticancer drug doxorubicin (Dox) was specifically and efficiently delivered to the prostate tumors. The PSMA-specific RNA aptamer by itself has been also recognized as tumor-specific drug delivery material by intercalating Dox. In this study, we compared two different methods for Dox delivery toward PSMA-positive cancer cells, namely intercalation of Dox into the aptamer (Apt-Dox), and encapsulation of Dox in the aptamosome (Apm-Dox). We observed that the Apm-Dox was superior to the Apt-Dox in specificity and Dox delivery efficiency toward PSMA(+) cancer cells.