Doxorubicin-conjugated platinum theranostic nanoparticles induce apoptosis via inhibition of a cell survival (PI3K/AKT) signaling pathway in human breast cancer cells

Herein, we report facile theranostic platinum nanoparticles (PtNPs) conjugated to an anticancer drug, doxorubicin (DOX), in unraveling the inhibition of a cell survival PI3K/AKT (phosphatidylinositol 3-kinase/protein kinase B) signaling pathway in MCF-7 and MDA-MB-231 human breast cancer cells. The significant features of our DOX@PtNPs as a theranostic platform are as follows: (i) drug release studies showed a progressive pH-dependent delivery; (ii) in vitro studies of DOX@PtNPs displayed a relatively higher cytotoxicity to breast cancer cells compared to unconjugated PtNPs and DOX; (iii) intracellular drug release studies showed a specific binding of DOX@PtNPs and their release within the cytoplasm and perinuclear region; (iv) DOX@PtNPs induced the apoptosis of cancer cells by DNA damage via the generation of elevated levels of reactive oxygen species and decreased mitochondrial membrane potential (ΔΨm), as evidenced by fluorescence microscopic studies; and (v) DOX@PtNPs inhibited the PI3K/AKT signaling pathway in breast cancer cells by activating PTEN, a tumor suppressor gene. The induced mitochondrial-dependent apoptotic pathway led to the activation of downstream caspases. Finally, our findings illustrate that DOX@PtNPs may serve as a better theranostic agent for cancer nanomedicine.