Fig. 2.

Overview of the affected pathways in the THP-1 cells after treatment with the free MTX and MTX loaded NPs. Red arrow = increased, blue arrow = decreased, Methotrexate enters the cell mainly via reduced folate receptor (RCF). Folylpolyglutamyl synthetase (FPGS) catalyses the polyglutamation of MTX to produce MTX polyglutamates (MTX-PGs). MTX-PGs are better retained intracellularly than MTX because they are not susceptible to the ATP-binding cassette (ABC) that is responsible for MTX efflux. MTX-PGs have higher affinity than MTX to thymidylate synthetase (TS) and phosphoribosylglycinamide formyltransferase (GART). Deoxyuridine-5-monophosphate (dUMP), deoxythymidine monophosphate (dTMP), 5′-phosphoribosyl-glycinamide (GAR), 5′-phosphoribosyl-N-formylglycinamide (FGAR) and nitric oxide (NO). Pathway analysis was performed using Metaboanalyst 3.0 software following LC-MS assays of cell (THP-1 and A549) extracts following incubation with MTX and MTX-loaded NPs for 24 h.