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Linehan A, O’Reilly M, McDermott R, O’Kane GM. Targeting KRAS mutations in pancreatic cancer: opportunities for future strategies. Front Med (Lausanne) 2024; 11:1369136. [PMID: 38576709 PMCID: PMC10991798 DOI: 10.3389/fmed.2024.1369136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 02/22/2024] [Indexed: 04/06/2024] Open
Abstract
Targeting the RAS pathway remains the holy grail of precision oncology. In the case of pancreatic ductal adenocarcinomas (PDAC), 90-92% harbor mutations in the oncogene KRAS, triggering canonical MAPK signaling. The smooth structure of the altered KRAS protein without a binding pocket and its affinity for GTP have, in the past, hampered drug development. The emergence of KRASG12C covalent inhibitors has provided renewed enthusiasm for targeting KRAS. The numerous pathways implicated in RAS activation do, however, lead to the development of early resistance. In addition, the dense stromal niche and immunosuppressive microenvironment dictated by oncogenic KRAS can influence treatment responses, highlighting the need for a combination-based approach. Given that mutations in KRAS occur early in PDAC tumorigenesis, an understanding of its pleiotropic effects is key to progress in this disease. Herein, we review current perspectives on targeting KRAS with a focus on PDAC.
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Affiliation(s)
- Anna Linehan
- Department of Medical Oncology, St Vincent’s University Hospital, Dublin, Ireland
| | - Mary O’Reilly
- Department of Medical Oncology, St Vincent’s University Hospital, Dublin, Ireland
| | - Ray McDermott
- Department of Medical Oncology, St Vincent’s University Hospital, Dublin, Ireland
| | - Grainne M. O’Kane
- Department of Medical Oncology, St James’s Hospital, Dublin, Ireland
- Princess Margaret Cancer Centre, Toronto, ON, Canada
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Whitley MJ, Tran TH, Rigby M, Yi M, Dharmaiah S, Waybright TJ, Ramakrishnan N, Perkins S, Taylor T, Messing S, Esposito D, Nissley DV, McCormick F, Stephen AG, Turbyville T, Cornilescu G, Simanshu DK. Comparative analysis of KRAS4a and KRAS4b splice variants reveals distinctive structural and functional properties. SCIENCE ADVANCES 2024; 10:eadj4137. [PMID: 38354232 DOI: 10.1126/sciadv.adj4137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 01/12/2024] [Indexed: 02/16/2024]
Abstract
KRAS, the most frequently mutated oncogene in human cancer, produces two isoforms, KRAS4a and KRAS4b, through alternative splicing. These isoforms differ in exon 4, which encodes the final 15 residues of the G-domain and hypervariable regions (HVRs), vital for trafficking and membrane localization. While KRAS4b has been extensively studied, KRAS4a has been largely overlooked. Our multidisciplinary study compared the structural and functional characteristics of KRAS4a and KRAS4b, revealing distinct structural properties and thermal stability. Position 151 influences KRAS4a's thermal stability, while position 153 affects binding to RAF1 CRD protein. Nuclear magnetic resonance analysis identified localized structural differences near sequence variations and provided a solution-state conformational ensemble. Notably, KRAS4a exhibits substantial transcript abundance in bile ducts, liver, and stomach, with transcript levels approaching KRAS4b in the colon and rectum. Functional disparities were observed in full-length KRAS variants, highlighting the impact of HVR variations on interaction with trafficking proteins and downstream effectors like RAF and PI3K within cells.
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Affiliation(s)
- Matthew J Whitley
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Timothy H Tran
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Megan Rigby
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Ming Yi
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Srisathiyanarayanan Dharmaiah
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Timothy J Waybright
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Nitya Ramakrishnan
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Shelley Perkins
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Troy Taylor
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Simon Messing
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Dominic Esposito
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Dwight V Nissley
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Frank McCormick
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, 1450 3rd Street, San Francisco, CA, USA
| | - Andrew G Stephen
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Thomas Turbyville
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Gabriel Cornilescu
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Dhirendra K Simanshu
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
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Larsen EK, Abreu-Blanco M, Rabara D, Stephen AG. KRAS4b:RAF-1 Homogenous Time-Resolved Fluorescence Resonance Energy Transfer Assay for Drug Discovery. Methods Mol Biol 2024; 2797:159-175. [PMID: 38570459 DOI: 10.1007/978-1-0716-3822-4_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2024]
Abstract
Homogenous time-resolved FRET (HTRF) assays have become one of the most popular tools for pharmaceutical drug screening efforts over the last two decades. Large Stokes shifts and long fluorescent lifetimes of lanthanide chelates lead to robust signal to noise, as well as decreased false positive rates compared to traditional assay techniques. In this chapter, we describe an HTRF protein-protein interaction (PPI) assay for the KRAS4b G-domain in the GppNHp-bound state and the RAF-1-RBD currently used for drug screens. Application of this assay contributes to the identification of lead compounds targeting the GTP-bound active state of K-RAS.
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Affiliation(s)
- Erik K Larsen
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA.
| | - Maria Abreu-Blanco
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Dana Rabara
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Andrew G Stephen
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
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Shree S, McLean MA, Stephen AG, Sligar SG. Revealing KRas4b topology on the membrane surface. Biochem Biophys Res Commun 2023; 678:122-127. [PMID: 37633182 PMCID: PMC10528110 DOI: 10.1016/j.bbrc.2023.08.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 08/16/2023] [Indexed: 08/28/2023]
Abstract
KRas4b is a membrane-bound regulatory protein belonging to the family of small GTPases that function as a molecular switch, facilitating signal transduction from activated membrane receptors to intracellular pathways controlling cell growth and proliferation. Oncogenic mutations locking KRas4b in the active GTP state are responsible for nearly 85% of all Ras-driven cancers. Understanding the membrane-bound state of KRas4b is crucial for designing new therapeutic approaches targeting oncogenic KRas-driven signaling pathways. Extensive research demonstrates the significant involvement of the membrane bilayer in Ras-effector interactions, with anionic lipids playing a critical role in determining protein conformations The preferred topology of KRas4b for interacting with signaling partners has been a long-time question. Computational studies suggest a membrane-proximal conformation, while other biophysical methods like neutron reflectivity propose a membrane-distal conformation. To address these gaps, we employed FRET measurements to investigate the conformation of KRas4b. Using fully post-translationally modified KRas4b, we designed a Nanodisc based FRET assay to study KRas4b-membrane interactions. We suggest an extended conformation of KRas4b relative to the membrane surface. Measurement of FRET donor - acceptor distances reveal that a negatively charged membrane surface weakly favors closer association with the membrane surface. Our findings provide insights into the role of anionic lipids in determining the dynamic conformations of KRas4b and shed light on the predominant conformation of its topology on lipid headgroups.
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Affiliation(s)
- Shweta Shree
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, United States
| | - Mark A McLean
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, United States
| | - Andrew G Stephen
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD, 21701, United States
| | - Stephen G Sligar
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, United States.
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Novel Insights into the Role of Kras in Myeloid Differentiation: Engaging with Wnt/β-Catenin Signaling. Cells 2023; 12:cells12020322. [PMID: 36672256 PMCID: PMC9857056 DOI: 10.3390/cells12020322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 01/07/2023] [Accepted: 01/11/2023] [Indexed: 01/19/2023] Open
Abstract
Cells of the HL-60 myeloid leukemia cell line can be differentiated into neutrophil-like cells by treatment with dimethyl sulfoxide (DMSO). The molecular mechanisms involved in this differentiation process, however, remain unclear. This review focuses on the differentiation of HL-60 cells. Although the Ras proteins, a group of small GTP-binding proteins, are ubiquitously expressed and highly homologous, each has specific molecular functions. Kras was shown to be essential for normal mouse development, whereas Hras and Nras are not. Kras knockout mice develop profound hematopoietic defects, indicating that Kras is required for hematopoiesis in adults. The Wnt/β-catenin signaling pathway plays a crucial role in regulating the homeostasis of hematopoietic cells. The protein β-catenin is a key player in the Wnt/β-catenin signaling pathway. A great deal of evidence shows that the Wnt/β-catenin signaling pathway is deregulated in malignant tumors, including hematological malignancies. Wild-type Kras acts as a tumor suppressor during DMSO-induced differentiation of HL-60 cells. Upon DMSO treatment, Kras translocates to the plasma membrane, and its activity is enhanced. Inhibition of Kras attenuates CD11b expression. DMSO also elevates levels of GSK3β phosphorylation, resulting in the release of unphosphorylated β-catenin from the β-catenin destruction complex and its accumulation in the cytoplasm. The accumulated β-catenin subsequently translocates into the nucleus. Inhibition of Kras attenuates Lef/Tcf-sensitive transcription activity. Thus, upon treatment of HL-60 cells with DMSO, wild-type Kras reacts with the Wnt/β-catenin pathway, thereby regulating the granulocytic differentiation of HL-60 cells. Wild-type Kras and the Wnt/β-catenin signaling pathway are activated sequentially, increasing the levels of expression of C/EBPα, C/EBPε, and granulocyte colony-stimulating factor (G-CSF) receptor.
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Zhang Y, Weh KM, Howard CL, Riethoven JJ, Clarke JL, Lagisetty KH, Lin J, Reddy RM, Chang AC, Beer DG, Kresty LA. Characterizing isoform switching events in esophageal adenocarcinoma. MOLECULAR THERAPY - NUCLEIC ACIDS 2022; 29:749-768. [PMID: 36090744 PMCID: PMC9437810 DOI: 10.1016/j.omtn.2022.08.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 08/14/2022] [Indexed: 12/14/2022]
Abstract
Isoform switching events with predicted functional consequences are common in many cancers, but characterization of switching events in esophageal adenocarcinoma (EAC) is lacking. Next-generation sequencing was used to detect levels of RNA transcripts and identify specific isoforms in treatment-naïve esophageal tissues ranging from premalignant Barrett’s esophagus (BE), BE with low- or high-grade dysplasia (BE.LGD, BE.HGD), and EAC. Samples were stratified by histopathology and TP53 mutation status, identifying significant isoform switching events with predicted functional consequences. Comparing BE.LGD with BE.HGD, a histopathology linked to cancer progression, isoform switching events were identified in 75 genes including KRAS, RNF128, and WRAP53. Stratification based on TP53 status increased the number of significant isoform switches to 135, suggesting switching events affect cellular functions based on TP53 mutation and tissue histopathology. Analysis of isoforms agnostic, exclusive, and shared with mutant TP53 revealed unique signatures including demethylation, lipid and retinoic acid metabolism, and glucuronidation, respectively. Nearly half of isoform switching events were identified without significant gene-level expression changes. Importantly, two TP53-interacting isoforms, RNF128 and WRAP53, were significantly linked to patient survival. Thus, analysis of isoform switching events may provide new insight for the identification of prognostic markers and inform new potential therapeutic targets for EAC.
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Affiliation(s)
- Yun Zhang
- Department of Surgery, Thoracic Surgery Section, University of Michigan, Ann Arbor, MI 48109, USA
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA
| | - Katherine M. Weh
- Department of Surgery, Thoracic Surgery Section, University of Michigan, Ann Arbor, MI 48109, USA
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA
| | - Connor L. Howard
- Department of Surgery, Thoracic Surgery Section, University of Michigan, Ann Arbor, MI 48109, USA
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jean-Jack Riethoven
- Nebraska Center for Biotechnology, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
- Nebraska Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Jennifer L. Clarke
- Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Kiran H. Lagisetty
- Department of Surgery, Thoracic Surgery Section, University of Michigan, Ann Arbor, MI 48109, USA
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jules Lin
- Department of Surgery, Thoracic Surgery Section, University of Michigan, Ann Arbor, MI 48109, USA
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA
| | - Rishindra M. Reddy
- Department of Surgery, Thoracic Surgery Section, University of Michigan, Ann Arbor, MI 48109, USA
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA
| | - Andrew C. Chang
- Department of Surgery, Thoracic Surgery Section, University of Michigan, Ann Arbor, MI 48109, USA
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA
| | - David G. Beer
- Department of Surgery, Thoracic Surgery Section, University of Michigan, Ann Arbor, MI 48109, USA
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA
| | - Laura A. Kresty
- Department of Surgery, Thoracic Surgery Section, University of Michigan, Ann Arbor, MI 48109, USA
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA
- Corresponding author Laura A. Kresty, PhD, Department of Surgery, Thoracic Surgery Section, University of Michigan, Ann Arbor, MI 48109, USA.
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