A pH-responsive CS-HA-DAP nanosystem enhances the antitumor activity of deer antler peptides by aggravating DNA damage stress and checkpoint imbalance in triple-negative breast cancer

Triple-negative breast cancer (TNBC) frequently exhibits p53 deficiency and increased reliance on DNA damage-checkpoint adaptation, yet effective targeted therapeutic strategies remain limited. Here, we characterized deer antler peptides (DAP) and developed a pH-responsive hyaluronic acid/chitosan nanosystem (CS-HA-DAP) to improve their antitumor activity. DAP consisted mainly of low- to medium-molecular-weight peptides and proteins and inhibited 4T1 cell viability, migration, and invasion, with relatively lower toxicity toward MCF-10A cells. Transcriptomic and molecular analyses indicated that DAP induced persistent DNA damage-associated stress, impaired sustained CHK1 signaling, and disrupted cell-cycle regulation, together with pyroptosis- and ferroptosis-related changes. Molecular docking and inhibitor-combination experiments further supported the involvement of TOP2A- and CHK1-related processes. CS-HA-DAP nanoparticles showed favorable physicochemical properties and acid-responsive release, and enhanced the anti-TNBC effects of free DAP in vitro and in vivo without evident additional toxicity. In orthotopic 4T1 tumor-bearing mice, CS-HA-DAP promoted tumor accumulation, suppressed tumor growth, and showed acceptable preliminary biosafety. Together, these findings identify DAP as a bioactive antitumor peptide mixture and support CS-HA-DAP as a delivery strategy for enhancing its therapeutic potential in TNBC.