Comparison of cancer cells cultured in 2D vs 3D reveals differences in AKT/mTOR/S6-kinase signaling and drug response

Abstract

3D cancer models are used as preclinical systems to mimic physiologic drug response. We provide evidence for robust changes of proliferation and metabolic capacity in 3D by systematically analyzing spheroids of colon cancer cell lines. Spheroids showed relative lower AKT/mTOR/S6K activities compared to cells cultured in 2D. We identified spatial alterations in signaling, as the level of phospho-rpS6 decreased from the spheroid surface to the center, closely recapitulating the tumor areas around vessels in vivo. These 3D-models displayed augmented anti-tumor response to AKT/mTOR/S6K- or MAPK-pathway inhibition compared to 2D. Inhibition of AKT/mTOR/S6K resulted in elevated ERK phosphorylation in 2D, whereas under these conditions MAPK-signaling was reduced in spheroids. Inhibition of the MAPK-pathway led to decreased AKT/mTOR/S6K-signaling in 3D but not in 2D. These data indicate a distinct rewiring of signaling in 3D and during treatment. Detached tumor cell clusters in vessels, in addition to circulating single tumor cells, play a putative role in metastasis in human cancers. Hence, the understanding of signaling in spheroids and the response in the 3D models upon drug treatment might be beneficial for anti-cancer therapies.