title: Identification of mutant K-Ras-dependent phenotypes using a panel of isogenic cell lines.
abstract: To assess the consequences of endogenous mutant K-Ras, we analyzed the signaling and biological properties of a small panel of isogenic cell lines. These include the cancer cell lines DLD1, HCT116, and Hec1A, in which either the WT or mutant K-ras allele has been disrupted, and SW48 colorectal cancer cells and human mammary epithelial cells in which a single copy of mutant K-ras was introduced at its endogenous genomic locus. We find that single copy mutant K-Ras causes surprisingly modest activation of downstream signaling to ERK and Akt. In contrast, a negative feedback signaling loop to EGFR and N-Ras occurs in some, but not all, of these cell lines. Mutant K-Ras also had relatively minor effects on cell proliferation and cell migration but more dramatic effects on cell transformation as assessed by growth in soft agar. Surprisingly, knock-out of the wild type K-ras allele consistently increased growth in soft agar, suggesting tumor-suppressive properties of this gene under these conditions. Finally, we examined the effects of single copy mutant K-Ras on global gene expression. Although transcriptional programs triggered by mutant K-Ras were generally quite distinct in the different cell lines, there was a small number of genes that were consistently overexpressed, and these could be used to monitor K-Ras inhibition in a panel of human tumor cell lines. We conclude that there are conserved components of mutant K-Ras signaling and phenotypes but that many depend on cell context and environmental cues.
authors.affiliation: Department of Discovery Oncology, Genentech Inc., South San Francisco, California 94080, USA.
authors.forename: Steffan
authors.initials: S
authors.lastname: Vartanian
authors.forename: Carolyn
authors.initials: C
authors.lastname: Bentley
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Brauer
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Senji
authors.initials: S
authors.lastname: Shirasawa
authors.forename: Takehiko
authors.initials: T
authors.lastname: Sasazuki
authors.forename: Jung-Sik
authors.initials: JS
authors.lastname: Kim
authors.forename: Pete
authors.initials: P
authors.lastname: Haverty
authors.forename: Eric
authors.initials: E
authors.lastname: Stawiski
authors.forename: Zora
authors.initials: Z
authors.lastname: Modrusan
authors.forename: Todd
authors.initials: T
authors.lastname: Waldman
authors.forename: David
authors.initials: D
authors.lastname: Stokoe
mesh_terms: D002460:Cell Line; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D011905:Genes, ras; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D009154:Mutation; D009857:Oncogenes / Q000235:genetics; D010641:Phenotype; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction; D014158:Transcription, Genetic; D018631:ras Proteins / Q000378:metabolism*
chemical_list: D034741:RNA, Small Interfering; D018631:ras Proteins