A Central Role for RAF-MEK-ERK Signaling in the Genesis and Maintenance of Pancreatic Ductal Adenocarcinoma

Although KRAS mutation is a hallmark of pancreatic ductal adenocarcinoma (PDA), mutated KRAS remains an intractable pharmacological target. Consequently, an understanding of the RAS effector pathway(s) required for PDA maintenance is critical for improved strategies to treat this disease. Here we demonstrate that expression of BRAFV600E, but not PIK3CAH1047R, in the mouse pancreas led to PanIn lesions. Moreover, concomitant expression of BRAFV600E and TP53R270H resulted in lethal PDA. A large panel of PDA cell line panel was deployed to derive genomic classifiers of MEK inhibitor sensitivity. This classifier correctly predicted survival benefit in two novel in vivo syngeneic, orthotopic models of PDA. Consequently, we conclude that RAF→MEK→ERK signaling is central to the initiation, progression and maintenance of PDA and propose predictive biomarkers of response to MEK inhibition. These data further emphasize the value of leveraging multiple experimental systems to prioritize pathways for intervention in human PDA. RNA was extracted from human PDA cell line samples and hybridized on Affymetrix U133 plus 2.0 microarrays. The CEL files were processed using R based Bioconductor and normalized values were obtained using RMA. RNA was extracted from mouse PDA cell lines and hybridized on Affymetrix Mouse 430a 2.0 microarrays. The CEL files were processed using R based Bioconductor and normalized values were obtained using RMA.