The overexpression of
ATP binding cassette (
ABC) transporters makes
tumor cells simultaneously resistant to several cytotoxic drugs. Impairing the energy metabolism of multidrug resistant (MDR) cells is a promising chemosensitizing strategy, but many metabolic modifiers are too toxic in vivo. We previously observed that the aminobisphosphonate
zoledronic acid inhibits the activity of
hypoxia inducible factor-1a (HIF-1a), a master regulator of
cancer cell metabolism. Free
zoledronic acid, however, reaches low intratumor concentration. We synthesized nanoparticle formulations of the aminobisphosphonate that allow a higher intratumor delivery of the
drug. We investigated whether they are effective metabolic modifiers and chemosensitizing agents against human MDR
cancer cells in vitro and in vivo. At not toxic dosage, nanoparticles carrying
zoledronic acid chemosensitized MDR cells to a broad spectrum of cytotoxic drugs, independently of the type of
ABC transporters expressed. The nanoparticles inhibited the
isoprenoid synthesis and the Ras/ERK1/2-driven activation of HIF-1α, decreased the transcription and activity of glycolytic
enzymes, the
glucose flux through the glycolysis and tricarboxylic acid cycle, the electron flux through the mitochondrial respiratory chain, the synthesis of
ATP. So doing, they lowered the
ATP-dependent activity of
ABC transporters, increasing the
chemotherapy efficacy in vitro and in vivo. These effects were more pronounced in MDR cells than in chemosensitive ones and were due to the inhibition of
farnesyl pyrophosphate synthase (FPPS), as demonstrated in FPPS-silenced
tumors. Our work proposes nanoparticle formulations of
zoledronic acid as the first not toxic metabolic modifiers, effective against MDR
tumors.