Identification of chemical compounds regulating PD‐L1 by introducing HiBiT‐tagged cells

Programmed death‐ligand 1 (PD‐L1) is a co‐inhibitory molecule expressed on tumor cells. Immune checkpoint inhibitors focusing on the PD‐L1 mechanism are now being studied for the treatment of various cancer types. However, the regulatory mechanism of PD‐L1 is yet to be fully clarified, and a high‐throughput system for comparing the abilities of small compounds in regulating PD‐L1 has not yet been established. Therefore, we created a HiBiT‐tagged lung adenocarcinoma cell line, PC9‐KI, for easier and faster detection of changes in PD‐L1 protein expression. Using PC9‐KI cells, we screened 1280 chemical compounds from the Library of Pharmacologically Active Compounds and identified microtubule polymerization inhibitors and thapsigargin as PD‐L1 upregulators and a p97 inhibitor as a PD‐L1 downregulator.