{"doi":"10.1074/jbc.ra119.011080","title":"RAS internal tandem duplication disrupts GTPase-activating protein (GAP) binding to activate oncogenic signaling","abstract":"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 RAS 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. 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 RAS 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. Driver mutations in KRAS, primarily at codons 12, 13, 61, and 146, have been well-characterized and are identified in 35–40% of cases of colorectal cancer (CRC). An additional 5–10% of CRC cases harbor a mutation in NRAS at functionally identical codons. RAS mutations are associated with decreased response to epidermal growth factor receptor (EGFR) inhibition and increased incidence of distant metastasis (1De Roock W. De Vriendt V. Normanno N. Ciardiello F. Tejpar S. KRAS, BRAF, PIK3CA, and PTEN mutations: Implications for targeted therapies in metastatic colorectal cancer.Lancet Oncol. 2011; 12 (21163703): 594-60310.1016/S1470-2045(10)70209-6Abstract Full Text Full Text PDF PubMed Scopus (432) Google Scholar). Recent advances in clinical genomic profiling have expanded recommended testing to look for a broader spectrum of mutations in KRAS, NRAS, and BRAF in patients with metastatic CRC to guide therapy planning","journal":"Journal of Biological Chemistry","year":2020,"id":86487,"datarank":0.6215272627572123,"base_score":2.639057329615259,"endowment":2.639057329615259,"self_citation_contribution":0.3958585994422889,"citation_network_contribution":0.22566866331492336,"self_endowment_contribution":0.3958585994422889,"citer_contribution":0.22566866331492336,"corpus_percentile":null,"corpus_rank":null,"citation_count":13,"citer_count":9,"citers_with_citation_signal":8,"citers_with_endowment":8,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9563,"is_data_producer":true,"deposit_databanks":{"PDB":["6OB2","1HE8","4G0N","3CON","6MBT"]},"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":441288,"name":"Thomas J. Turbyville","orcid":"0000-0003-2638-9520","position":1,"is_corresponding":false},{"id":310703,"name":"Srisathiyanarayanan Dharmaiah","orcid":"0000-0001-7630-3962","position":2,"is_corresponding":false},{"id":441289,"name":"Megan Rigby","orcid":"0000-0002-6268-0414","position":3,"is_corresponding":false},{"id":292243,"name":"Rendong Yang","orcid":"0000-0002-9512-2240","position":4,"is_corresponding":false},{"id":441290,"name":"Ting-You Wang","orcid":"0000-0003-4354-3198","position":5,"is_corresponding":false},{"id":442508,"name":"John Columbus","orcid":null,"position":6,"is_corresponding":false},{"id":239230,"name":"Robert M. Stephens","orcid":null,"position":7,"is_corresponding":false},{"id":267812,"name":"Troy Taylor","orcid":"0000-0001-6775-629X","position":8,"is_corresponding":false},{"id":442509,"name":"Drew Sciacca","orcid":null,"position":9,"is_corresponding":false},{"id":441291,"name":"Getiria Onsongo","orcid":"0000-0001-5305-3251","position":10,"is_corresponding":false},{"id":442510,"name":"Anne E. Sarver","orcid":null,"position":11,"is_corresponding":false},{"id":405462,"name":"Subbaya Subramanian","orcid":"0000-0002-2544-480X","position":12,"is_corresponding":false},{"id":233731,"name":"Dwight V. Nissley","orcid":"0000-0001-7523-116X","position":13,"is_corresponding":false},{"id":310706,"name":"Dhirendra K. Simanshu","orcid":"0000-0002-9717-4618","position":14,"is_corresponding":false},{"id":259423,"name":"Emil Lou","orcid":"0000-0002-1607-1386","position":15,"is_corresponding":false},{"id":235000,"name":"Andrew C. Nelson","orcid":"0000-0002-4741-0010","position":0,"is_corresponding":true}],"reference_count":53,"raw_metadata":null,"created_at":"2026-07-18T21:59:03.706190Z","pmid":"32393580","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}