pH-responsive HA/chitosan nanoplatform delivering deer antler polypeptide to induce DNA damage and checkpoint imbalance for TNBC therapy

Triple-negative breast cancer (TNBC) lacks effective targeted therapeutic options and often relies on stress-adaptation pathways for survival. Deer antler peptides (DAP) is a complex mixture of peptides and proteins with potential bioactivity, but its therapeutic application is limited by delivery inefficiency. In this study, we characterized DAP, investigated its antitumor effects in TNBC, and developed a pH-responsive hyaluronic acid/chitosan nanodelivery system (CS-HA-DAP) to improve its biological performance. Proteomic analysis identified 79 proteins and 122 peptides in DAP; DAP consisted mainly of low- to medium-molecular-weight proteins and peptides and dose-dependently inhibited the viability of 4T1 cells, with half-maximal inhibitory concentrations of 1.62 mg/mL, and also impaired migration and invasion of 4T1 cells, with relatively lower toxicity toward normal MCF-10 A cells. Transcriptomic and molecular analyses showed that DAP induced persistent DNA damage-associated stress, time-dependent γ-H2AX accumulation, incomplete sustained CHK1 activation, and dysregulation of cell-cycle regulators, together with pyroptosis- and ferroptosis-related changes, which were rescuable by Fer-1 and VX-765. CETSA showed that GDQGPVGR physically bound TOP2A and CHK1, and docking together with inhibitor-combination assays supported the involvement of TOP2A- and CHK1-related processes; furthermore, DAP exhibited synergy with etoposide and MK-8776. To improve delivery, we constructed CS-HA-DAP nanoparticles by coupling DAP to hyaluronic acid via EDC and NHS conjugation followed by ionic gelation with chitosan and tripolyphosphate. The optimized nanoparticles, which showed spherical morphology and measured 158.2 nm with a zeta potential of +28.7 mV, achieved a high encapsulation efficiency of 89.2% and a drug loading capacity of 57.2%. They also showed marked pH-responsive release, with substantially higher cumulative release at pH 5.0 than at pH 7.4, reaching 89.18% at pH 5.0 versus 23.43% at pH 7.4 over 48 h. CS-HA-DAP enhanced the inhibitory effects of free DAP on 4T1 cell viability, migration, and invasion while maintaining relatively low toxicity toward MCF-10 A cells. In orthotopic 4T1 tumor-bearing mice, orally administered CS-HA-DAP showed tumor-associated fluorescence signals in tumors, suppressed tumor growth more effectively than free DAP, achieving a tumor growth inhibition (TGI) rate of 85.74% versus 53.57%, and exhibited acceptable preliminary biosafety. DAP is a bioactive peptide mixture with antitumor activity associated with sustained genomic stress and checkpoint imbalance in TNBC, and CS-HA-DAP represents an effective nanodelivery strategy that enhances its therapeutic efficacy, with improved tumor accumulation and acceptable preliminary safety. This work provides a nanobiotechnology-based approach for improving the antitumor potential of complex natural peptide mixtures and offers a promising lead for further translational development.