The cellular context-dependent consequences of Apc mutations on gene regulation and cellular behavior

The spectrum of genetic mutations differs among cancers in different organs, implying a cellular context-dependent effect of the genetic aberrations. However, the extent to which the cellular context affects the consequences of oncogenic mutations remains to be fully elucidated. We reprogrammed colon tumor cells in an Apc Min/+ mouse model, in which the loss of the Apc gene plays a critical role in tumor development, and established reprogrammed tumor cells (RTCs) that exhibit pluripotent stem cell (PSC)-like signatures of gene expression. We show that the majority of the genes in the RTCs that were affected by the Apc mutations did not overlap with the genes that were affected in the intestine or those that were affected by the accumulation of beta-catenin in PSCs. The RTCs lacked pluripotency but exhibited the increased expression of Cdx2 and a differentiation propensity that was biased toward the trophectoderm cell lineage. The genetic rescue of the mutated Apc allele conferred pluripotency on the RTCs and enabled their differentiation into various cell types in vivo. The re-disruption of Apc in the RTC-derived differentiated cells resulted in neoplastic growth that was exclusive to the intestine, yet the majority of intestinal lesions remained pre-tumoral microadenomas. These results highlight the significant influence of the cellular context on gene regulation, cellular plasticity, and cellular behavior in response to the loss of the Apc function. Our results also imply that transition from microadenomas to macroscopic tumors is reprogrammable, which underscores the importance of epigenetic regulation on colon tumor promotion.

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Hashimoto K, Yamada Y, Semi K, Yagi M, Tanaka A, Itakura F, Aoki H, Kunisada T, Woltjen K, Haga H, Sakai Y, Yamamoto T, Yamada Y