To determine which KRAS effectors were responsible for tumor progression, we created four effector domain mutants (S35, G37, E38 and C40) in G12V-activated KRAS and expressed these alone or with BrafV600E in mouse lungs...
Co-expression of Kras(G12V) and Braf(D631A) in mouse lung cells markedly enhances tumour initiation, a phenomenon mediated by Craf kinase activity, and effectively accelerates tumour progression when activated in advanced lung adenocarcinomas.
We hypothesized that tumor progression was because of concomitant activation of the mitogen-activated protein kinase pathway downstream of Kras(G12D) expression promoting cell survival and that the therapeutic effect of PF-04691502 would be enhanced by combinatory inhibition of MEK using PD-0325901.
The transformed phenotype of IOE(CMYC) cells was further enhanced in concert with KRAS(G12V)/BRAF(V600E) expression, as in vitro analyses indicated that IOE(CMYC) cells had undergone morphological and phenotypic changes characteristic of neoplastic progression.
Other organs such as pancreas, liver, and small intestine do not exhibitneoplastic progression within 6 weeks following K-Ras(G12D) activation and do not show a potent tumor suppressor response.