A tumor microenvironment-stimuli responsive nano-prodrug for overcoming gemcitabine chemoresistance by co-delivered miRNA-21 modulator.

Gemcitabine (Gem) has been recommended as a first-line clinical chemotherapeutics for pancreatic ductal adenocarcinoma (PDAC) treatment. Gem treatment could generate chemoresistance associated with abnormal expressions of multiple miRNAs. In the PDAC setting, miRNA-21 (miR-21) overexpression is an important contributing factor of inducing Gem chemoresistance. Inhibition of miR-21 can significantly increase Gem chemosensitivity, which requires an efficient delivery platform to conduct combinational Gem and miR-21 siRNA (miR-21i) therapy. Herein, we synthesized a tumor microenvironment (TME) stimuli-responsive poly(beta-amino ester)s (PBAE)-based polymer nano-prodrug (miR-21i@HA-Gem-SS-P12) that could co-deliver miR-21 siRNA and Gem. The disulfide linkages conjugating GEM onto PBAE can be triggered by elevated reduction stimulus in TME to release the cargo Gem. The hyaluronic acid (HA) fabrication further improved the drug accumulation at the tumor site. Benefiting from the multiple functional improvements and synergism between Gem and miR-21i, the miR-21i@HA-Gem-SS-P12 nano-prodrugs displayed superior tumor inhibition in PDACand. This study established an effective stimuli-responsive nano-prodrug strategy for cooperative treatment with small molecule agents and nucleotide modulators in PDAC.