ABSTRACT
Activating KRAS mutations are major oncogenic drivers in multiple tumor types. Synthetic lethal screens have previously been used to identify targets critical for the survival of KRAS mutant cells, but their application to drug discovery has proven challenging, possibly due in part to a failure of monolayer cultures to model tumor biology. Here, we report the results of a high-throughput synthetic lethal screen for small molecules that selectively inhibit the growth of KRAS mutant cell lines in soft agar. Chemoproteomic profiling identifies the target of the most KRAS-selective chemical series as dihydroorotate dehydrogenase (DHODH). DHODH inhibition is shown to perturb multiple metabolic pathways. In vivo preclinical studies demonstrate strong antitumor activity upon DHODH inhibition in a pancreatic tumor xenograft model.
Subject(s)
Oxidoreductases Acting on CH-CH Group Donors/metabolism , Pancreatic Neoplasms/drug therapy , Proto-Oncogene Proteins p21(ras)/metabolism , Pyrimidines/metabolism , Animals , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Cell Proliferation/drug effects , Dihydroorotate Dehydrogenase , Drug Screening Assays, Antitumor , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Female , Humans , Mice , Mice, SCID , Mutation , Neoplasms, Experimental/drug therapy , Neoplasms, Experimental/metabolism , Neoplasms, Experimental/pathology , Oxidoreductases Acting on CH-CH Group Donors/antagonists & inhibitors , Pancreatic Neoplasms/metabolism , Pancreatic Neoplasms/pathology , Proto-Oncogene Proteins p21(ras)/antagonists & inhibitors , Proto-Oncogene Proteins p21(ras)/genetics , Pyrimidines/chemistry , Small Molecule Libraries/chemistry , Small Molecule Libraries/pharmacology , Tumor Cells, CulturedABSTRACT
Poor homing of systemically infused cells to disease sites may limit the success of exogenous cell-based therapy. In this study, we screened 9,000 signal-transduction modulators to identify hits that increase mesenchymal stromal cell (MSC) surface expression of homing ligands that bind to intercellular adhesion molecule 1 (ICAM-1), such as CD11a. Pretreatment of MSCs with Ro-31-8425, an identified hit from this screen, increased MSC firm adhesion to an ICAM-1-coated substrate in vitro and enabled targeted delivery of systemically administered MSCs to inflamed sites in vivo in a CD11a- (and other ICAM-1-binding domains)-dependent manner. This resulted in a heightened anti-inflammatory response. This represents a new strategy for engineering cell homing to enhance therapeutic efficacy and validates CD11a and ICAM-1 as potential targets. Altogether, this multi-step screening process may significantly improve clinical outcomes of cell-based therapies.
