title: A requirement for wild-type Ras isoforms in mutant KRas-driven signalling and transformation.
abstract: The mutant forms of KRas, NRas and HRas drive the initiation and progression of a number of human cancers, but less is known about the role of WT (wild-type) Ras alleles and isoforms in cancer. We used zinc-finger nucleases targeting HRas and NRas to modify both alleles of these genes in the mutant KRas-driven Hec1A endometrial cancer cell line, which normally expresses WT copies of these genes. The disruption of either WT isoform of Ras compromised growth-factor-dependent signalling through the ERK (extracellular-signal-regulated kinase) pathway. In addition, the disruption of HRas hindered the activation of Akt and subsequent downstream signalling. This was associated with decreased proliferation, increased apoptosis and decreased anchorage-independent growth in the HRas-disrupted cells. However, xenograft tumour growth was not significantly affected by the disruption of either NRas or HRas. As expected, deleting the mutant allele of KRas abolished tumour growth, whereas deletion of the remaining WT copy of KRas increased the tumorigenic properties of these cells; deleting a single copy of either HRas or NRas did not mimic this effect. The present study demonstrates that the WT copies of HRas, NRas and KRas play unique roles in the context of mutant KRas-driven tumours.
authors.affiliation: Department of Discovery Oncology, Department of Bioinformatics, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Bentley
authors.forename: Stefanie S
authors.initials: SS
authors.lastname: Jurinka
authors.forename: Noelyn M
authors.initials: NM
authors.lastname: Kljavin
authors.forename: Steffan
authors.initials: S
authors.lastname: Vartanian
authors.forename: Sree R
authors.initials: SR
authors.lastname: Ramani
authors.forename: Lino C
authors.initials: LC
authors.lastname: Gonzalez
authors.forename: Kebing
authors.initials: K
authors.lastname: Yu
authors.forename: Zora
authors.initials: Z
authors.lastname: Modrusan
authors.forename: Pan
authors.initials: P
authors.lastname: Du
authors.forename: Richard
authors.initials: R
authors.lastname: Bourgon
authors.forename: Richard M
authors.initials: RM
authors.lastname: Neve
authors.forename: David
authors.initials: D
authors.lastname: Stokoe
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000737:chemistry / Q000235:genetics*; D005260:Female; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000235:genetics; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry* / Q000235:genetics*; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000737:chemistry* / Q000235:genetics*; D016283:Proto-Oncogene Proteins p21(ras) / Q000737:chemistry / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics*; D018631:ras Proteins / Q000737:chemistry* / Q000235:genetics*
chemical_list: C117307:KRAS protein, human; D008565:Membrane Proteins; D050505:Mutant Proteins; D020033:Protein Isoforms; D011518:Proto-Oncogene Proteins; D020558:GTP Phosphohydrolases; C579846:NRAS protein, human; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins