ULK-101 is a potent and selective inhibitor of ULK1 (IC50s: 8.3/30 nM for ULK1/ULK2). It can suppress autophagy.

ULK2:30 nM (cell free), ULK1:8.3 nM (cell free)

U2OS cells were treated with AZD8055 for 2.5 hr, a catalytic mTOR inhibitor that strongly induces autophagy in U2OS cells and observed that the abundance of DFCP1-positive puncta increased over 3-fold. Co-treatment of cells with 5 μM ULK-101 completely abrogated the formation of DFCP1-positive structures induced by AZD8055 treatment, consistent with the loss of Beclin 1 phosphorylation.

IC50 data for ULK1 and ULK2 was generated using 10-point IC50Profiler assays with half-log dilutions from top concentrations of 10 μM (4 replicates) and 1 μM (4 replicates), giving 8 data points for most concentrations in the curve. For selectivity profiling, KinaseProfiler assays with wild-type human kinase panels were performed in duplicate using 500 nM SBI-0206965, 40 nM ULK-101, or 15 nM ULK-100. For each kinase reaction, the Km concentration of ATP was used. The percent activity remaining and percent inhibition were calculated from negative control wells. For selectivity profiling, relative inhibition was calculated by dividing the percent inhibition of each kinase by the percent inhibition of ULK1. GraphPad Prism 7 was used for IC50 determinations by fitting curves with variable slope (four-parameter) non-linear regression models using top and bottom constraints of 100% and 0%, respectively.

Cells (U2OS or NSCLC) were seeded on tissue culture treated 96-well plates at 1,000 cells per well in RPMI-1640 media supplemented with 10% FBS. Twenty-four hours later, media was aspirated, wells rinsed with 1x DPBS, and replaced with full media (FM) or Optistarve (OS) with a concentration gradient of ULK-101 (final concentrations of 100 μM, 50 μM, 25 μM, 12.5 μM, 6.25 μM, 3.1 μM, 1.6 μM, 0.8 μM, 0.4 μM, or 0 μM). Two days later, media (and ULK-101) was aspirated, wells were rinsed with 1x DPBS, and all wells replaced with FM. Five days later, relative ATP levels were measured using a luminescent CellTiter-Glo assay.