| Autor: |
Clayton J; Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201, United States.; Division of Applied Regulatory Science, Office of Clinical Pharmacology, Office of Translational Sciences, Center for Drug Evaluation and Research, United States Food and Drug Administration, Silver Spring, MD 20993, United States., Romany A; Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201, United States., Matenoglou E; Department of Biochemistry, Department of Medicine, Department of Oncology, Montefiore Einstein Comprehensive Cancer Center, Albert Einstein College of Medicine, New York, NY 10461, United States., Gavathiotis E; Department of Biochemistry, Department of Medicine, Department of Oncology, Montefiore Einstein Comprehensive Cancer Center, Albert Einstein College of Medicine, New York, NY 10461, United States., Poulikakos PI; Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States., Shen J; Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201, United States. |
| Abstrakt: |
Aberrant signaling of BRAF V600E is a major cancer driver. Current FDA-approved RAF inhibitors selectively inhibit the monomeric BRAF V600E and suffer from tumor resistance. Recently, dimer-selective and equipotent RAF inhibitors have been developed; however, the mechanism of dimer selectivity is poorly understood. Here, we report extensive molecular dynamics (MD) simulations of the monomeric and dimeric BRAF V600E in the apo form or in complex with one or two dimer-selective (PHI1) or equipotent (LY3009120) inhibitor(s). The simulations uncovered the unprecedented details of the remarkable allostery in BRAF V600E dimerization and inhibitor binding. Specifically, dimerization retrains and shifts the α C helix inward and increases the flexibility of the DFG motif; dimer compatibility is due to the promotion of the α C-in conformation, which is stabilized by a hydrogen bond formation between the inhibitor and the α C Glu501. A more stable hydrogen bond further restrains and shifts the α C helix inward, which incurs a larger entropic penalty that disfavors monomer binding. This mechanism led us to propose an empirical way based on the co-crystal structure to assess the dimer selectivity of a BRAF V600E inhibitor. Simulations also revealed that the positive cooperativity of PHI1 is due to its ability to preorganize the α C and DFG conformation in the opposite protomer, priming it for binding the second inhibitor. The atomically detailed view of the interplay between BRAF dimerization and inhibitor allostery as well as cooperativity has implications for understanding kinase signaling and contributes to the design of protomer selective RAF inhibitors. |
