Proteomic characterization of GSK3β knockout shows altered cell adhesion and metabolic pathway utilisation in colorectal cancer cells

Abstract

Glycogen-specific kinase (GSK3{beta}) is an integral regulator of the Wnt signalling pathway as well as many other diverse signalling pathways and processes. Dys-regulation of GSK3{beta} is implicated in many different pathologies, including neurodegenerative disorders as well as many different tumour types. In the context of tumour development, GSK3{beta} has been shown to play both oncogenic and tumour suppressor roles, depending upon tissue, signalling environment or disease progression. Although multiple substrates of the GSK3{beta} kinase have been identified, the wider protein networks within which GSK3{beta} participates are not well known, and the consequences of these interactions not well understood. In this study, LC-MS/MS expression analysis was performed using knockout GSK3{beta} colorectal cancer cells and isogenic controls in colorectal cancer cell lines carrying dominant stabilizing mutations of {beta}-Catenin. Consistent with the role GSK3{beta}, we found that {beta}-Catenin levels and canonical Wnt activity are unaffected by knockout of GSK3{beta} and therefore use this knockout cell model to identify other processes in which GSK3{beta} is implicated. Quantitative proteomic analysis revealed perturbation of proteins involved in cell-cell adhesion, and we characterize the phenotype and altered proteomic profiles associated with this. We also characterize the perturbation of metabolic pathways resulting from GSK3{beta} knockout and identify defects in glycogen metabolism. In summary, using a precision colorectal cancer cell-line knockout model with constitutively activated {beta}-Catenin we are able to identify several of the diverse pathways and processes associated with GSK3{beta} function.