Dataset Information

A Systems Mechanism for KRAS Mutant Allele Specific Responses to Targeted Therapy

ABSTRACT: Cancer treatment decisions are increasingly guided by which specific genes are mutated within each patient’s tumor. For example, agents inhibiting the epidermal growth factor receptor (EGFR) benefit many colorectal cancer (CRC) patients, with the general exception of those whose tumor includes a KRAS mutation. However, among the various KRAS mutations, the G13D mutation behaves differently; for unknown reasons, CRC patients with the KRAS G13D mutation (also written KRASG13D) appear to benefit from the EGFR-blocking antibody cetuximab. Controversy surrounds this observation, because it appears to contradict the well-established mechanisms of EGFR signaling and of RAS mutations. Here, we identified a systems-level, mechanistic basis that explains why KRASG13D cancers respond to EGFR inhibition. We first investigated the problem with a computational model of RAS signaling, which unexpectedly revealed that the known biophysical differences between the three most common KRAS mutant proteins are sufficient to generate different sensitivities to inhibition. Computation and experimentation together revealed a non-intuitive, mutant-specific dependency of wild-type RAS activation by EGFR that is determined by the interaction strength between KRAS and the tumor suppressor neurofibromin (NF1). KRAS mutants that strongly interact with NF1 drive wild-type RAS activation in an EGFR independent manner through competitive inhibition of NF1, whereas KRAS G13D cells remain dependent upon EGFR for wild-type Ras activation because they cannot competitively inhibit NF1 due to a weak interaction between these two proteins. Overall, our work demonstrates how systems approaches enable mechanism-based inference in genomic medicine and can help identify patients for selective therapeutic strategies.

INSTRUMENT(S): Orbitrap Fusion

ORGANISM(S): Homo Sapiens (human)

DISEASE(S): Colon Cancer

SUBMITTER: Jolene Diedrich

LAB HEAD: Edward Stites

PROVIDER: PXD014755 | Pride | 2020-05-27

REPOSITORIES: Pride

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Publications

A systems mechanism for KRAS mutant allele-specific responses to targeted therapy.

McFall Thomas T Diedrich Jolene K JK Mengistu Meron M Littlechild Stacy L SL Paskvan Kendra V KV Sisk-Hackworth Laura L Moresco James J JJ Shaw Andrey S AS Stites Edward C EC

Science signaling 20190924 600

Cancer treatment decisions are increasingly guided by which specific genes are mutated within each patient's tumor. For example, agents inhibiting the epidermal growth factor receptor (EGFR) benefit many colorectal cancer (CRC) patients, with the general exception of those whose tumor includes a KRAS mutation. However, among the various KRAS mutations, that which encodes the G13D mutant protein (KRASG13D) behaves differently; for unknown reasons, KRASG13D CRC ...[more]

PMID: 31551296

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Project description:The small GTPase KRAS transmits signals from cell surface receptors to various downstream signaling pathways, thereby regulating a multitude of cellular processes. Activating KRAS mutations occur in approximately 30% of human cancers and contribute to malignant transformation through constitutive activation of downstream signaling cascades. These mutations cluster in several hotspots, with codons 12 and 13 being most commonly. It has been suggested that the position and type of amino acid exchange influence the transforming capacity of mutant KRAS proteins. To address this hypothesis, we used MCF10A human mammary epithelial cells to establish isogenic cell lines that express eight different cancer-associated KRAS mutations (G12C, G12D, G12V, G13C, G13D, A18D, Q61H, K117N) at physiological levels, and investigated the biochemical and functional consequences of the different KRAS variants in vitro. In addition, selected effects were evaluated in comparison to cells that overexpress mutant KRAS. The overall effects of mutants expressed at normal levels were moderate compared to overexpressed variants, but allowed delineation of biological functions that were related to specific alleles rather than KRAS expression level. None of the mutations induced morphological changes or migratory abilities. KRAS-G12D, -G12V, -G13D, and -K117N were able to mediate EGF-independent proliferation, whereas anchorage-independent growth was primarily induced by the K117N and Q61H variants. Analysis of known RAS effectors showed that none of the mutations led to increased phosphorylation of ERK, PDK1, or AKT. Both codon 13 mutations were associated with increased EGFR expression, which was not seen with other variants. Finally, comparative gene expression analysis of MCF10A-G13D versus MCF10A-G12D revealed distinct transcriptional changes, such as enhanced cytokine and p53 signaling, upon G13D expression. Together, we describe a useful resource for investigating the function of multiple KRAS mutations and provide insights into the differential effects of these variants in MCF10A cells.

Dataset Information

A Systems Mechanism for KRAS Mutant Allele Specific Responses to Targeted Therapy

Publications

A systems mechanism for KRAS mutant allele-specific responses to targeted therapy.

Similar Datasets

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