Tumor microenvironment-activatable neuropeptide-drug conjugates enhanced tumor penetration and inhibition via multiple delivery pathways and calcium deposition

Peptide-drug conjugates have achieved considerable development and application as a novel strategy for targeted delivery of anticancer drugs. Bioactive peptides induced calcium deposition can irreversibly assist inhibition of tumors. However, active regulation of calcium level through signal transduction of bioactive substances has not been reported yet. In this study, novel neuropeptide-doxorubicin conjugates(NP-DOX) with lysosome-specific acid response were described for neuropeptide Y_1 receptor(Y_1R)-overexpressed triple-negative breast cancer. The delivery mechanism of NP-DOX was clarified that diverse pathways were involved, including intracellular and intercellular transport. Importantly, up-regulation of Y_1 R-mediated intracellular calcium level via second messenger inositol triphosphate was presented in NP-DOX treated MDA-MB-231 cells. In vivo antitumor efficacy demonstrated that NP-DOX showed less organ toxicity and enhanced tumor inhibition benefited from its controlled release and Y_1R-mediated calcium deposition, compared with free DOX. This bioconjugate is a proof-of-concept confirming that neuropeptide-mediated control of signaling responses in neuropeptide-drug conjugates enables great potential for further applications in tumor chemotherapy.