Oncogenic PI3K signaling induces senescence in the extrahepatic bile duct that is independent of the Trp53 pathway. A, Left, representative SA-β-Gal staining, and p53 and p21 IHC of BilIN (top) and PanIN (bottom) lesions of a Pdx1-Cre;Pik3caH1047R/+ mouse. Right, representative SA-β-Gal staining of wild-type extrahepatic bile duct and pancreas. Scale bars, 20 μm. B, Representative IHC cleaved caspase-3 staining of BilIN and ADM/PanIN of a Pdx1-Cre;LSL-Pik3caH1047R/+ mouse and an ADM/PanIN of Pdx1-Cre;LSL-KrasG12D/+ mouse. Scale bars, 50 μm. C, Quantification of cleaved caspase-3–positive epithelial cells in BilIN and ADM/PanIN lesions of the indicated genotypes. Each dot represents one animal (mean ± SD; P values are indicated, two-tailed Student t test). HPF, high-power field; pos., positive. D, Kaplan–Meier survival curves of the indicated genotypes (**, P < 0.01; ***, P < 0.001, log-rank test). E, Top: tumor-type distribution according to histologic analysis of the extrahepatic bile duct and pancreas of Pdx1-Cre;LSL-Pik3caH1047R/+, Pdx1-Cre;LSL-Pik3caH1047R/+;p53f/+, and Pdx1-Cre;LSL-Pik3caH1047R/+;p53f/f mice. Note: Reduced ECC fraction in mice with the Pdx1-Cre;Pik3caH1047R/+;p53f/f genotype (P = 0.02, Fisher exact test). Bottom: tumor-type distribution according to histologic analysis of the extrahepatic bile duct and pancreas of Pdx1-Cre;LSL-KrasG12D/+ and Pdx1-Cre;LSL-KrasG12D/+;p53f/+ mice. F, Representative hematoxylin and eosin (H&E) staining of ECC and PDAC of Pdx1-Cre;LSL-Pik3caH1047R/+;p53f/+ and Pdx1-Cre;LSL-Pik3caH1047R/+;p53f/f mice. G, Representative H&E staining of the common bile duct and PDAC of a Pdx1-Cre;LSL-KrasG12D/+;p53f/+ mouse. Scale bars, 50 μm for micrographs and 20 μm for insets. The Pdx1-Cre;Pik3caH1047R/+ and Pdx1-Cre;LSL-KrasG12D/+ cohorts shown in D and E are the same as those shown in Fig. 2C and D.