Aptamer-armed nanostructures improve the chemotherapy outcome of triple-negative breast cancer.

Triple-negative breast cancer is an aggressive subtype of breast cancer that is primarily treated using systemic chemotherapy due to the lack of a specific cell surface marker for drug delivery. Cancer cell-specific aptamer-mediated drug delivery is a promising targeted chemotherapy for marker-unknown cancers. Using a poorly differentiated carcinoma cell-specific DNA aptamer (PDGC21T), we formed a self-assembling circinate DNA nanoparticle (Apt21TNP) that binds triple-negative breast cancer cells. Using our previously designed pH-sensitive dendrimer-conjugated doxorubicin (DDOX) as the payload, we found that each nanoparticle loaded 30 doxorubicin molecules to form an Apt21TNP-DDOX nanomedicine that is stable in human plasma. Upon cell binding, Apt21TNP-DDOX is internalized by triple-negative breast cancer cells through the macropinocytosis pathway. Once inside cells, the low pH microenvironment in lysosomes induces doxorubicin drug payload release from Apt21TNP-DDOX. Our in vitro studies demonstrate that Apt21TNP-DDOX can preferentially bind triple-negative breast cancer cells to induce cell death. Furthermore, we show that Apt21TNP-DDOX can accumulate in subcutaneous MDA-MB-231 tumors in mice following systemic administration to reduce tumor burden, minimize side effects, and improve animal survival. Together, our results demonstrate that Apt21TNP-mediated doxorubicin delivery is a potent, targeted chemotherapy for triple-negative breast cancer that may alleviate side effects in patients.