B6.129-Kras^tm3Bbd/J

Stock number: 027010
Product name: Kras^FSFG12Vgeo
Research areas: Cancer Research, Developmental Biology Research, Research Tools

Description

Mice bearing the FLP recombinase-inducible Kras^FSFG12V allele may be useful for studying K-RAS driven lung adenocarcinomas.

Detailed description

Kras^FSFG12V mice contain a 5’ frt-flanked STOP-neo cassette, followed by a G12V mutation in the Kras (v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog) gene. Ras genes are small GTPases that act downstream of receptors and nonreceptor tyrosine protein kinases in multiple pathways to transfer information to the nucleus. K-ras has been found to be primarily activated in human tumors in pancreatic, colon, and lung cancer. The unrecombined Kras^FSFG12V allele is null. Hence, homozygous Kras^FSFG12V embryos die at midgestation as the Kras^–/– mice. When bred to mice expressing FLP Recombinase, removal of the frt-flanked STOP cassette allows expression of Kras^G12V, commonly found in human tumors.

Tracheal infection of these Kras^FSFG12V mice with Adeno-FLP particles induces lung adenomas and adenocarcinomas with an incidence and latency similar to that observed in the Kras^LSLG12Vgeo mice (Stock No. 026924) infected with Adeno-Cre particles.

Breeding to bitransgenic Elas-tTA/tetO-FLP mice that express FLP recombinase under the control of the elastase promoter in a tet-off system allows selective expression of the KrasG12V oncoprotein in cells of pancreatic acinar lineage. Untreated mice develop PanIN lesions and pancreatic ductal adenocarcinomas with an incidence and latency similar to that observed with Kras^LSLG12Vgeo mice carrying the Elas-tTA/tetO-Cre transgenes.

Crossing Kras^FSFG12V mice with strains carrying floxed alleles of targets with potential therapeutic value, allows the temporal and spatial separation of tumor development and target ablation. This strategy makes it possible to determine the therapeutic properties of the target in a well established tumors.

Development

A targeting vector was designed to insert a frt-flanked PGK-neo-STOP cassette upstream of the Kras (v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog) initiation codon. This event also introduced two point mutations in codon 12 of exon 1 (GGT to GTA) replacing a glycine residue with a valine (G12V), a mutation commonly found in human tumors. The construct was electroporated into (129X1/SvJ x 129S1/Sv)F1-Kitl⁺-derived R1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts and the resulting chimeric males were bred to C57BL/6 females to generate a colony of Kras^FSFG12V mice. These mice were bred to C57BL/6.OlaHsd mice for at least 5 generations. Upon arrival at The Jackson Laboratory, mice were bred to C57BL/6J (Stock No. 000664) for at least one generation to establish the colony.

Allele

Symbol: Kras^tm3Bbd
Name: targeted mutation 3, Mariano Barbacid
MGI accession ID: MGI:5645350
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); Null/Knockout; Humanized sequence
Marker symbol: Kras
Marker name: Kirsten rat sarcoma viral oncogene homolog
Chromosome: 6
Strain of origin: (129X1/SvJ x 129S1/Sv)F1-Kitl⁺
Expressed genes: Kras,Kirsten rat sarcoma viral oncogene homolog,mouse, laboratory
Site of expression: Expression of Kras^tm3Bbd follows FLP recombination to remove the frt-flanked STOP cassette.
Molecular note: A targeting vector was designed to insert a FRT-flanked PGK-neo-STOP cassette upstream of the Kras (v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog) initiation codon. This event also introduced two point mutations in codon 12 of exon 1 (GGT to GTA) replacing a glycine residue with a valine (G12V), a mutation commonly found in human tumors.