A Combination of Targeted Sunitinib Liposomes and Targeted Vinorelbine Liposomes for Treating Invasive Breast Cancer.

Regular chemotherapy cannot eradicate invasive breast cancer cells and the residual cancer cells will form vasculogenic mimicry (VM) channels under hypoxic conditions to provide nutrients for cancer masses prior to angiogenesis. This phenomenon is a major reason for the recurrence of invasive breast cancer after treatment. In this study, a novel type of targeted liposomes was developed by modifying a mitochondria-tropic material, D-a-tocopheryl polyethylene glycol 1000 succinate- triphenylphosphine conjugate (TPGS1000-TPP), to encapsulate sunitinib and vinorelbine separately and a combination of the two targeted drug liposomes was used to treat invasive breast cancer as well as VM channels. Evaluations were performed in breast cancer MCF-7 cells and highly invasive breast cancer MDA-MB-435S cells in vitro and in mice. The results determined that the functional material (TPGS1000-TPP) and suitable size of the liposomes (90-100 nm) resulted in prolonged blood circulation, an enhanced permeability retention (EPR) effect in cancer tissue, and a mitochondrial targeting effect. Targeted drug liposomes were internalized via cellular uptake and accumulated in the mitochondria of invasive breast cancer cells or VM channel-forming cancer cells to induce acute cytotoxic injury and apoptosis. Activated apoptotic enzymes caspase 9 and caspase 3 as well as down-regulated VM channel-forming indicators (MMP-9, EphA2, VE-Cadherin, FAK and HIF-1α) contributed to significantly enhanced efficacy. Therefore, a combination of targeted sunitinib liposomes and targeted vinorelbine liposomes may provide an effective strategy for treating invasive breast cancer and prevent relapse arising from VM channels.