Journal: Nature Communications

Article Title: CETSA screening identifies known and novel thymidylate synthase inhibitors and slow intracellular activation of 5-fluorouracil

doi: 10.1038/ncomms11040

Figure Lengend Snippet: ( a ) Overview of the assay principle with live K562 cells seeded into a 384-well PCR plate. The plate contains controls or library compounds that are taken up by the cells. Following a pre-incubation period the plate is transiently heated for 3 min followed by cooling and cell lysis. Part of the cell lysate is transferred to a detection plate, to which antibodies and AlphaScreen beads are added to allow measurements of remaining soluble TS. ( b ) CETSA derived T agg curves for TS in K562 cells in the presence of DMSO (0.5%) (green circle), 15 μM floxuridine (blue triangle) or 1 μM raltitrexed (magenta square). All data were normalized to the response observed for each treatment condition at the lowest test temperature. The solid line represents the best fit to the Boltzmann sigmoid equation resulting in an apparent T agg of 46.7±0.2 °C for the DMSO control, whereas both floxuridine and raltitrexed stabilized TS above 65 °C (we do not consider higher T agg values reliable as these temperatures influence cell membrane integrity ). The vertical dotted line is at 50 °C, the temperature selected for the isothermal screen. Data are provided as the average and standard error of mean (s.e.m.) from two independent experiments performed in duplicate for raltitrexed and as individual data points from one experiment in duplicate for floxuridine. ( c ) ITDRF CETSA of floxuridine (blue triangle) at 50 °C based on raw data from the AlphaScreen readings. The solid line represents the best fit to a saturation binding curve resulting in an EC 50 of 47±16 pM. Data are provided as two individual data points from one test occasion. ( d ) The corresponding ITDRF CETSA for raltitrexed (magenta square) at 50 °C resulting in an EC 50 of 0.75±0.2 nM. Data are provided as two individual data points from one test occasion.

Article Snippet: Finally 5 μl of the diluted compounds were transferred to a 384 well hardshell PCR plate (HSR480, BIORAD) using a Bravo liquid handling platform equipped with a 384-well head (Agilent).

Techniques: Incubation, Lysis, Amplified Luminescent Proximity Homogenous Assay, Derivative Assay, Control, Membrane, Binding Assay