RAS internal tandem duplication disrupts GTPase-activating protein (GAP) binding to activate oncogenic signaling

Abstract

<jats:p>The oncogene RAS is one of the most widely studied proteins in cancer biology, and mutant active RAS is a driver in many types of solid tumors and hematological malignancies. Yet the biological effects of different <jats:italic>RAS</jats:italic> mutations and the tissue-specific clinical implications are complex and nuanced. Here, we identified an internal tandem duplication (ITD) in the switch II domain of NRAS from a patient with extremely aggressive colorectal carcinoma. Results of whole-exome DNA sequencing of primary and metastatic tumors indicated that this mutation was present in all analyzed metastases and excluded the presence of any other clear oncogenic driver mutations. Biochemical analysis revealed increased interaction of the RAS ITD with Raf proto-oncogene Ser/Thr kinase (RAF), leading to increased phosphorylation of downstream MAPK/ERK kinase (MEK)/extracellular signal–regulated kinase (ERK). The ITD prevented interaction with neurofibromin 1 (NF1)–GTPase–activating protein (GAP), providing a mechanism for sustained activity of the RAS ITD protein. We present the first crystal structures of NRAS and KRAS ITD at 1.65–1.75 Å resolution, respectively, providing insight into the physical interactions of this class of RAS variants with its regulatory and effector proteins. Our in-depth bedside-to-bench analysis uncovers the molecular mechanism underlying a case of highly aggressive colorectal cancer and illustrates the importance of robust biochemical and biophysical approaches in the implementation of individualized medicine.</jats:p>

Erdheim–Chester Disease Due to a Novel Internal Duplication of NRAS: Response to Targeted Therapy with Cobimetinib

“…Notably, this case represents a novel NRAS mutation, distinct from those found in previous studies [14,15]. Intriguingly, a somewhat similar NRAS internal tandem duplication (albeit shorter; c.164_193dup) was identified in a patient with colon cancer by Nelson et al [16]. These authors demonstrated that the mutation enhanced the interaction of RAS with RAF (Raf proto-oncogene Ser/Thr kinase), resulting in increased MEK (ERK activator kinase, also known as MAP2K1) phosphorylation and downstream ERK (extracellular signalregulated kinase) activity.…”

Q61 mutant-mediated dynamics changes of the GTP-KRAS complex probed by Gaussian accelerated molecular dynamics and free energy landscapes

“…By now, a number of molecular structures of GTP-and GDPbound KRAS have been determined by X-ray and NMR experiments from different work groups, [10][11][12][13][14][15] which provide signicant structural basis for understanding function of KRAS. According to function of structural domains, the conserved catalytic domain of KRAS is divided into two functional lobes, namely the effector lobe (residues 1-86) and the allosteric lobe (residues 87-166).…”