K-RasG12D expression induces hyperproliferation and aberrant signaling in primary hematopoietic stem/progenitor cells.

Van Meter ME, Díaz-Flores E, Archard JA, Passegué E, Irish JM, Kotecha N, Nolan GP, Shannon K, Braun BS
Blood. 2007 109 (9): 3945-52

PMID: 17192389 · PMCID: PMC1874575 · DOI:10.1182/blood-2006-09-047530

Defining how cancer-associated mutations perturb signaling networks in stem/progenitor populations that are integral to tumor formation and maintenance is a fundamental problem with biologic and clinical implications. Point mutations in RAS genes contribute to many cancers, including myeloid malignancies. We investigated the effects of an oncogenic Kras(G12D) allele on phosphorylated signaling molecules in primary c-kit(+) lin(-/low) hematopoietic stem/progenitor cells. Comparison of wild-type and Kras(G12D) c-kit(+) lin(-/low) cells shows that K-Ras(G12D) expression causes hyperproliferation in vivo and results in abnormal levels of phosphorylated STAT5, ERK, and S6 under basal and stimulated conditions. Whereas Kras(G12D) cells demonstrate hyperactive signaling after exposure to granulocyte-macrophage colony-stimulating factor, we unexpectedly observe a paradoxical attenuation of ERK and S6 phosphorylation in response to stem cell factor. These studies provide direct biochemical evidence that cancer stem/progenitor cells remodel signaling networks in response to oncogenic stress and demonstrate that multi-parameter flow cytometry can be used to monitor the effects of targeted therapeutics in vivo. This strategy has broad implications for defining the architecture of signaling networks in primary cancer cells and for implementing stem cell-targeted interventions.

MeSH Terms (14)

Animals Cell Proliferation Extracellular Signal-Regulated MAP Kinases Granulocyte-Macrophage Colony-Stimulating Factor Hematopoietic Stem Cells Mice Mice, Transgenic Myeloproliferative Disorders Neoplastic Stem Cells Point Mutation Proto-Oncogene Proteins p21(ras) Ribosomal Protein S6 Kinases Signal Transduction STAT5 Transcription Factor

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