Cosilencing of PKM-2 and MDR-1 Sensitizes Multidrug-Resistant Ovarian Cancer Cells to Paclitaxel in a Murine Model of Ovarian Cancer.

Tumor multidrug resistance (MDR) is a serious clinical challenge that significantly limits the effectiveness of cytotoxic chemotherapy. As such, complementary therapeutic strategies are being explored to prevent relapse. The altered metabolic state of cancer cells, which perform aerobic glycolysis, represents an interesting target that can enable discrimination between healthy cells and cancer cells. We hypothesized that cosilencing of genes responsible for aerobic glycolysis and for MDR would have synergistic antitumor effect. In this study, siRNA duplexes against pyruvate kinase M2 and multidrug resistance gene-1 were encapsulated in hyaluronic acid-based self-assembling nanoparticles. The particles were characterized for morphology, size, charge, encapsulation efficiency, and transfection efficiency. In vivo studies included biodistribution assessment, gene knockdown confirmation, therapeutic efficacy, and safety analysis. The benefit of active targeting of cancer cells was confirmed by modifying the particles' surface with a peptide targeted to epidermal growth factor receptor, which is overexpressed on the membranes of the SKOV-3 cancer cells. To augment the studies involving transplantation of a paclitaxel-resistant cell line, an in vivo paclitaxel resistance model was developed by injecting repeated doses of paclitaxel following tumor inoculation. The nanoparticles accumulated significantly in the tumors, hindering tumor volume doubling time (P < 0.05) upon combination therapy in both the wild-type (2-fold) and resistant (8-fold) xenograft models. Although previous studies indicated that silencing of MDR-1 alone sensitized MDR ovarian cancer to paclitaxel only modestly, these data suggest that concurrent silencing of PKM-2 improves the efficacy of paclitaxel against MDR ovarian cancer.