| Autor: |
Brown BP; Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN 37235.; Center for Structural Biology, Vanderbilt University, Nashville, TN 37232., Zhang YK; Department of Medicine, Division of Hematology and Oncology, Vanderbilt University Medical Center, Nashville, TN 37232., Kim S; Department of Chemistry, University of Akron, Akron, OH 44325., Finneran P; Menten AI, San Francisco, CA 94111., Yan Y; Department of Medicine, Division of Hematology and Oncology, Vanderbilt University Medical Center, Nashville, TN 37232., Du Z; Department of Medicine, Division of Hematology and Oncology, Vanderbilt University Medical Center, Nashville, TN 37232., Kim J; Department of Chemistry, University of Akron, Akron, OH 44325., Hartzler AL; Department of Chemistry, University of Akron, Akron, OH 44325., LeNoue-Newton ML; Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN 37232., Smith AW; Department of Chemistry, University of Akron, Akron, OH 44325., Meiler J; Center for Structural Biology, Vanderbilt University, Nashville, TN 37232.; Department of Chemistry, Vanderbilt University, Nashville, TN 37232.; Institute for Drug Discovery, Leipzig University Medical School, Leipzig, SAC 04103, Germany., Lovly CM; Department of Medicine, Division of Hematology and Oncology, Vanderbilt University Medical Center, Nashville, TN 37232.; Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN 37232. |
| Abstrakt: |
Oncogenic mutations within the epidermal growth factor receptor (EGFR) are found in 15 to 30% of all non-small-cell lung carcinomas. The term exon 19 deletion (ex19del) is collectively used to refer to more than 20 distinct genomic alterations within exon 19 that comprise the most common EGFR mutation subtype in lung cancer. Despite this heterogeneity, clinical treatment decisions are made irrespective of which EGFR ex19del variant is present within the tumor, and there is a paucity of information regarding how individual ex19del variants influence protein structure and function. Herein, we identified allele-specific functional differences among ex19del variants attributable to recurring sequence and structure motifs. We built all-atom structural models of 60 ex19del variants identified in patients and combined molecular dynamics simulations with biochemical and biophysical experiments to analyze three ex19del mutations (E746_A750, E746_S752 > V, and L747_A750 > P). We demonstrate that sequence variation in ex19del alters oncogenic cell growth, dimerization propensity, enzyme kinetics, and tyrosine kinase inhibitor (TKI) sensitivity. We show that in contrast to E746_A750 and E746_S752 > V, the L747_A750 > P variant forms highly active ligand-independent dimers. Enzyme kinetic analysis and TKI inhibition experiments suggest that E746_S752 > V and L747_A750 > P display reduced TKI sensitivity due to decreased adenosine 5'-triphosphate K m . Through these analyses, we propose an expanded framework for interpreting ex19del variants and considerations for therapeutic intervention. |
