KRAS Withdrawal in Cholangiocarcinoma Leads to Immune Infiltration and Tumor Regression.

Abstract

Cholangiocarcinoma (CCA) is a liver cancer subtype with poor survival rates. KRAS mutations are found in 15-40% of CCA, representing a new potential treatment target. Whether KRAS inhibition leads to CCA tumor regression is unknown, partly due to the lack of conditional animal models. A conditional TRE.Kras/Trp53 knock-out (TKP) CCA mouse model is engineered using the transposon system and CRISPR-Cas9. Withdrawal of Krasresults in >90% tumor regression by day 7, accompanied by infiltration and enrichment of activated CD8T cells, shown by IHC, co-IF staining, and single-cell RNA-Seq. Bulk RNA-Seq of TKP cell line suggested that Kraswithdrawal stimulates the transforming growth factor beta pathway and induces senescence. Cytokine array characterizes the secretion of pro-inflammatory factors, including IL-15 and CCL17. Lentiviral overexpression of murine IL-15 and CCL17 delays CCA tumor progression in a syngeneic transplant model. Consistently, expression of IL-15 resulted in blockade of tumor progression in the TKP CCA model. These findings highlight the importance of oncogenic Kras in CCA tumor maintenance and underscore KRAS inhibition as a potential therapeutic approach for CCA.