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Comparison of the genetic extinction of NRAS to pharmacological MEK inhibition in an inducible mouse model of melanoma

ABSTRACT: Since direct pharmacological inhibition of RAS has thus far been unsuccessful, we explored system biology approaches to identify synergistic drug combination(s) that can mimic direct RAS inhibition. Leveraging an inducible mouse model of NRAS-mutant melanoma, we compare pharmacological MEK inhibition to complete NRAS-Q61K extinction in vivo. NRAS-Q61K extinction leads to a complete and durable tumor regression by enhancing both apoptosis and cell cycle arrest. By contrast, MEK inhibition only produces tumor stasis at best and we find that it robustly activates apoptosis but does not significantly impede proliferation. We used microarrays to determine which transcripts were affected by NRAS-Q61K extinction but insufficiently by MEK inhibition. We selected a single comparative timepoint, 4 days post-treatment. Downstream analyses included GSEA and TRAP algorithms, leading to the identification of a differentially affected CDK4-driven proliferation network. Immune genes were also identified as significant, but control experiments determined these to be largely the off-target effects of doxycycline and not of NRAS-Q61K extinction. The iNRAS-475 mouse melanoma cell line was injected intradermally into nude mice which were fed 2mg/ml doxycycline water. Tumors were allowed to reach 200-500mm3 after 6 weeks. Mice were then treated with vehicle or 100mg/kg of the AZD6244 MEK inhibitor, or doxycyline was withdrawn from the diet. Each sample represents a distinct tumor and thus provide six biological, not technical replicates per cohort.

ORGANISM(S): Mus musculus

SUBMITTER: Lawrence Kwong

PROVIDER: E-GEOD-39984 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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