A smart-responsive Y-shaped DNA scaffold drug conjugate achieving precise and synergetic tumor chemo-gene therapy via promoting tumor apoptosis and activating the anti-tumor immunity

•Smart-responsive DNA scaffold drug conjugate (sYDD) is developed.•sYDD enables smart therapy via sequential activation by APE1 and miR-21.•sYDD achieves synergistic chemo-gene therapy and tumor regression.•RNA-seq confirms the immunostimulatory effects of Bcl-2 suppression.•In vitro and in vivo assays substantiate the immune activation effects of sYDD. Constructing precise delivery systems to enhance the antitumor efficacy of drugs represents a pressing clinical practice need. The characteristics of suitable physiological stability, flexible tunable size, and highly programmable architecture make functional DNA scaffolds an ideal solution to this requirement. Here, we designed DNA oligonucleotide probes Y1, Y2 and Y3 to construct a smart-responsive Y-shaped DNA scaffold drug conjugate (sYDD). This sYDD incorporates two AS1411 aptamers, an apurinic/apyrimidinic (AP) site, a B-cell lymphoma-2 (Bcl-2) antisense oligonucleotide (ASO) and a doxorubicin (DOX)-carrying sequence. The Bcl-2 ASO and DOX within sYDD could be responsively released in tumor cells that exhibited high expression of apurinic/apyrimidinic endonuclease 1 (APE1) and microRNA-21 (miR-21). And the in vitro and in vivo experiments demonstrated that sYDD exhibited substantial antitumor efficiency. Moreover, the flow cytometry and RNA sequencing results proved that the proposed sYDD effectively activated anti-tumor immune responses. This strategy provides an alternative approach for designing synergistic chemo-gene drug conjugates, which facilitates the development of precision tumor treatment modalities.