Conditions-specific quantitative network rewiring of colon cancer-associated KRAS mutations in Caco-2 cell line

Ras is a key switch controlling cell behaviour. In the active, GTP-bound form, Ras can interact with numerous effector proteins in a mutually exclusive manner, suggesting that individual Ras-effector complexes engage in larger cellular (sub)complexes. A detailed characterisation of these (sub)complexes and how they are altered in specific contexts is not fully understood. Focusing on KRAS, we performed AP-MS experiments of exogenous expressed FLAG-KRAS wild-type and three oncogenic mutants in the human Caco-2 cell line exposed to 16 growth contexts – mimicking conditions relevant in the colon and colorectal cancer. We identified four effectors present in complex with KRAS in almost all conditions (“condition-general”) and nine effectors that only form complexes in some contexts (“condition-specific”). We computationally predicted earlier that the latter effectors need additional domains to be recruited to the plasma membrane for efficient recruitment to KRAS. Analysing all interactors in complex with KRAS per condition, we find that the different growth conditions had a larger impact on complex rewiring than the mutation status of KRAS. We also reconstructed effector-mediated (sub)complexes and linked changes in (sub)complex compositions in the different conditions to phenotypic changes. Altogether, our work shows the impact of environmental contexts on network rewiring, which provides insides into tissue-specific signalling mechanisms. Our work also sheds light on why individual KRAS oncogenic mutants may be causing cancer only in specific tissues – despite KRAS being expressed in most cells and tissues.