The Effect Of Fatty Acid Oxidation Inhibitor Etomoxir On Bladder Cancer

Background Bladder cancer(BCa)is one of the most common malignancies of urinary system.The global incidence of BCa has been increasing gradually in recent years.Tumor cells rely on aerobic glycolysis as their main energy resource,which is known as Warburg effect.Recent researches highlighted the importance of lipid metabolism in tumor progression and certain cancers even turn to fatty acids as main fuel.Related studies have identified alterations of fatty acid metabolism in BCa,indicating there may exists active fatty acid oxidation(FAO)in BCa.Objective To investigate the effect and mechanism of FAO inhibition on BCa with etomoxir.Methods Microarray and bioinformatics analysis were taken between human normal bladder and BCa tissues.Substrates and products of FAO were measured by free fatty acid(FFA),nicotinamide adenine dinucleotide phosphate(NADPH),adenosine triphosphate(ATP),oil red O and gas chromatography–flame ionization detection(GCFID).We explored the influence of etomoxir on tumor growth in vitro and in vivo with xenograft model,clonogenic survival and MTT assays.Wound healing and transwell chamber assay to detect the migration and invasion rate.Flow cytometry analysis to detect the change of cell cycle and apoptosis.Reverse transcription-polymerase chain reaction(RT-PCR),immunofluorescence,immunohistochemistry,western blot,and enzyme-linked immunosorbent assay to detect gene and protein expressions.Results Microarray and bioinformatics analysis showed that fatty acid metabolism was activated in BCa compared with normal bladder.FFA level was increased in BCa compared with paracancerous tissues.Inhibition of FAO with etomoxir caused lipid accumulation,decreased ATP and NADPH level.Etomoxir and ST1326 reduced BCa cell proliferation and clonogenic survival rate in vitro.Furthermore,etomoxir treatment inhibited BCa xenograft growth in vivo.Moreover,etomoxir induced BCa cell cycle arrest at G0/G1 phase with increased expression of peroxisome proliferators-activated receptors gamma(PPAR?),enhanced DNA-binding activity of nuclear PPAR?,and alterations in fatty acid oxidation associated gene expression,.The cell cycle arrest and growth inhibition caused by etomoxir could be partially reversed by PPAR? antagonist GW9662.In addition,we also observed reduced migration and invasion rate of BCa cells treated with etomoxir via affecting epithelial-mesenchymal transitions(EMT)-related proteins.Conclusions On conclusion,our studies indicated that inhibition of activated FAO in BCa with etomoxir could suppress cell growth and motility,and induce cell cycle arrest via PPAR? related pathway.