SERUM- AND GLUCOCORTICOID-INDUCED KINASE SGK1 DIRECTLY PROMOTES THE DIFFERENTIATION OF COLORECTAL CANCER CELLS AND RESTRAINS METASTASIS

Background and Aims: The molecular events that determine intestinal cell differentiation are poorly understood and it is unclear whether it is primarily a passive event or an active process. It is clinically important to gain a greater understanding of the process, since in colorectal cancer (CRC), the degree of differentiation of a tumour is associated with patient survival. SGK1 has previously been identified as a gene that is principally expressed in differentiated intestinal cells. In colorectal cancer (CRC), there is marked downregulation of SGK1 compared to normal tissue. Methods: An inducible SGK1 viral overexpression system was utilised to induce re-expression of SGK1 in CRC cell lines. Transcriptomic and phenotypic analyses of these CRC lines was performed and validation in mouse and human cohorts was performed. Results: We demonstrate that SGK1 is upregulated in response to, and an important controller of, intestinal cell differentiation. Re-expression of SGK1 in CRC cell lines results in features of differentiation, decreased migration rates, and inhibition of metastasis in an orthotopic xenograft model. These effects may be mediated in part by SGK1-induced PKP3 expression and increased degradation of MYC. Conclusions: Our results suggest that SGK1 is an important mediator of differentiation of colorectal cells and may inhibit CRC metastasis.

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