Psma 617

In short, following a previously published protocol [12 (link),19 (link),20 (link)], 100 µL of sterile sodium acetate solution (0.4 M, pH 5.5) and 1.25 µL ascorbic acid solution (20% w/w) were added to ca 30–40 µL (1.25 GBq in total) of non-carrier added Lutetium-177 (ITM Isotope Technologies Munich, Garching, Germany). To this solution, 20 nmol (volume circa 2 µL) of PSMA-617 (MedChemExpress, Monmouth Junction, NJ, USA) were added and labeled by incubating on a shaker at 95 °C for 15 min after which the reaction was terminated by cooling to room temperature. At 0 and 15 min, respectively, 1 µL of the solution was added to an instant thin layer chromatography (iTLC) strip. Sodium citrate solution (0.2 M, pH 2) was used as mobile phase, and the percentage of free ¹⁷⁷Lu (which migrates with the solvent front) was determined by analyzing the iTLC strips with a phosphor imager system (Cyclone Plus Phosphor Imager, PerkinElmer, Inc., Waltham, MA, USA). A sterile 0.9% sodium chloride solution was added, and the radioligand diluted (1:3 or 1:7), a sample for iTLC taken, and pH tested before injections in mice. ¹⁷⁷Lu-PSMA was labeled at a specific activity of 62 MBq/nmol (judged most effective for therapy by Fendler et al. [19 (link)]), and the radiochemical purity of the radioligand was >99%.

PSMA-617 (vipivotide tetraxetan, HY-117410), 2-PMPA (HY-100788) were purchased from MedchemExpress (Monmouth Junction, NJ, USA). The sulforhodamine B (SRB) based In vitro toxicology assay kit (TOX6) and L-glutamic acid monosodium salt hydrate (monosodium glutamate, MSG, G5889) were purchased from Sigma-Aldrich (Overijse, Belgium). Kynurenic acid (S4719), memantine HCl (S2043), capric acid (S6906) and (-)-Dizocilpine (MK 801) maleate (S2857) were purchased from SelleckChem (Planegg, Germany). UBP 302 (2079) was purchased from Tocris Biosciences (Abingdon, UK). (RS)-MCPG (sc-202325), (RS)-CPPG (sc-203448), LY341495 (sc-361244A) and UBP1112 (sc-204368) were purchased from Santa Cruz Biotechnologies (Heidelberg, Germany). Compounds were dissolved either in H₂O, 0.05 M NaOH or DMSO.