Hydroxycitrate-loaded exosomes demonstrate enhanced therapeutic efficacy against lung adenocarcinoma by inhibiting the metabolic enzyme ATP citrate lyase

Abstract

Cancer cells display the Warburg effect resulting in the production of excess pyruvate that is converted to acetyl-CoA in the mitochondria. Acetyl-CoA is further converted to citrate in the mitochondria. Meanwhile, in the cytosol, citrate is cleaved by ATP citrate lyase (ACLY) that regenerates acetyl-CoA and oxaloacetate. Recently, ACLY has been recognized as a potential target owing to its overexpression in several cancers, including non-small cell lung cancer. The aim of this study was to develop an ACLY-targeting exoformulation, where bovine milk-derived exosomes were surface-conjugated with folate and loaded with the natural ACLY inhibitor potassium hydroxycitrate. The therapeutic efficacy of potassium hydroxycitrate was enhanced by encapsulating it in bovine milk exosomes, and the anti-cancer potential of this exoformulation was evaluated in urethane-induced lung adenocarcinoma murine model. Potassium hydroxycitrate-loaded exosomes, which were surface-conjugated with folate (Exo-KH), exhibited a particle size of ∼183 nm and a practical loading efficiency of ∼16.8%. The exoformulation was found to be spherical in shape as characterized by scanning electron microscopy. Pharmacokinetic studies confirmed the continuous release of hydroxycitrate from the exoformulation, and Exo-KH administered mice showed inhibition of lung tumor growth. The mRNA expression levels of ACLY and other metabolic enzymes, such as FASN, HMGCR, SERBP1c, were also reduced in the exoformulation-treated group as compared with its free form-treated group. ACLY activity was also observed to be decreased in serum and tumor lysates of exoformulation-treated mice. This study demonstrates the potential of using bovine milk exosomes encapsulating potassium hydroxycitrate as a new chemotherapeutic option for non-small cell lung cancer.