A Potent and Selective ULK1 Inhibitor Suppresses Autophagy and Sensitizes Cancer Cells to Nutrient Stress

In response to stress, cancer cells generate nutrients and energy through a cellular recycling process called autophagy, which can promote survival and tumor progression. Accordingly, autophagy inhibition has emerged as a potential cancer treatment strategy. Inhibitors targeting ULK1, an essential and early autophagy regulator, have provided proof of concept for targeting this kinase to inhibit autophagy; however, these are limited individually in their potency, selectivity, or cellular activity. In this study, we report two small molecule ULK1 inhibitors, ULK-100 and ULK-101, and establish superior potency and selectivity over a noteworthy published inhibitor. Moreover, we show that ULK-101 suppresses autophagy induction and autophagic flux in response to different stimuli. Finally, we use ULK-101 to demonstrate that ULK1 inhibition sensitizes KRAS mutant lung cancer cells to nutrient stress. ULK-101 represents a powerful molecular tool to study the role of autophagy in cancer cells and to evaluate the therapeutic potential of autophagy inhibition.