Chromatin accessbility profile (ATAC-Seq) in mouse colonic epithelium and tumor expressing endogenouse K-Ras-WT or oncogenic K-Ras-G12D

K-Ras is frequently hyperactivated in human cancers through gain-of-function mutations that drive tumorigenesis. K-RasG12D, the most common oncogenic K-Ras allele, triggers massive transcriptomic and proteomic changes in the murine colon. Here, we report a comprehensive profile of physiological miRNA targets in murine colonic epithelium and tumor expressing K-RasG12D. Combining it with transcriptional, transcriptomic, and proteomic landscapes, we uncover a K-RasG12D-induced global suppression of miRNA activity that up-regulates hundreds of genes post-transcriptionally. K-RasG12D suppresses Csnk1a1 and Csnk2a1, which can decrease Ago2 phosphorylation at Ser825/829/831/835. Hypo-phosphorylated Ago2 increases binding with mRNA, reducing its regulatory activity by locking Ago2 in a small set of target transcripts. While expanding the repertoire of miRNA targets identified, it functionally decreases active Ago2, resulting in global de-repression of miRNA targets. Our findings establish a regulatory relationship among K-Ras, Csnk1a1/Csnk2a1, and Ago2 that provides a mechanistic link between oncogenic K-Ras and the up-regulation of hundreds of miRNA targets. ATAC-Seq of colonic epithelium from two mouse models: Fabp-Cre/+ (Control) and Fabp-Cre/+; K-Ras-G12D/+ (Experimental), and colonic tumor from two mouse models: Villin-CreER/+; Apc(fl/fl) (Control) and Villin-CreER/+; Apc(fl/fl); K-Ras-G12D/+ (Experimental). Tissues from the control model expressed K-Ras-WT. Tissues from the experimental model expressed oncogenic K-Ras-G12D.