Gene expression differences between the pancreatic tissues of Pdx1-Cre;KrasLSL-G12D and Pdx1-Cre;KrasLSL-G12D;IKK2/betaF/F mice

Constitutive Kras and NF-kappaB activation is identified as signature alterations in human pancreatic ductal adenocarcinoma (PDAC). However, the mechanisms of constitutive NF-kappaB activation in KrasG12D-induced PDAC are not yet understood. Here, we report that pancreas-targeted IKK2/beta inactivation inhibited NF-kappaB activation and completely suppressed PDAC development in KrasG12D and KrasG12D;Ink4a/Arf mutant mice, demonstrating a genetic link between IKK2/beta and KrasG12D in PDAC inception. Our findings reveal that KrasG12D-activated AP-1 induces IL-1alpha, which in turn activates NF-kappaB and its target genes IL-1alpha and p62, to initiate IL-1alpha/p62 feedforward loops for inducing and sustaining NF-kappaB activity. Furthermore, IL-1alpha overexpression correlates with Kras mutation, constitutive NF-kappaB activity, and poor survival in PDAC patients. Therefore, our findings establish a pathway linking duel feedforward loops of IL-1alpha/p62 through which IKK2/beta/NF-kappaB is activated by KrasG12D. To study Kras-induced inflammatory responses and to identify differentially expressed genes between the pancreatic tissues of Pdx1-Cre;KrasLSL-G12D and Pdx1-Cre;KrasLSL-G12D;IKK2/betaF/F mice, cDNA microarray analysis was performed.