The Hippo pathway effector, Yes-associated protein (YAP), is a transcriptional coactivator implicated in cholangiocarcinoma (CCA) pathogenesis. YAP is known to be regulated by a serine/threonine kinase relay module (MST1/2-LATS1/2) culminating in phosphorylation of YAP at Serine 127 and cytoplasmic sequestration. However, YAP also undergoes tyrosine phosphorylation, and the role of tyrosine phosphorylation in YAP regulation remains unclear. Herein, YAP regulation by tyrosine phosphorylation was examined in human and mouse CCA cells, as well as patient-derived xenograft (PDX) models. YAP was phosphorylated on tyrosine 357 (Y357) in CCA cell lines and PDX models. SRC family kinase (SFK) inhibition with dasatinib resulted in loss of YAPY357 phosphorylation, promoted its translocation from the nucleus to the cytoplasm, and reduced YAP target gene expression, including cell lines expressing a LATS1/2-resistant YAP mutant in which all serine residues were mutated to alanine. Consistent with these observations, precluding YAPY357 phosphorylation by site-directed mutagenesis (YAPY357F) excluded YAP from the nucleus. Targeted siRNA experiments identified LCK as the SFK that most potently mediated YAPY357 phosphorylation. Likewise, inducible CRISPR/Cas9-targeted LCK deletion decreased YAPY357 phosphorylation and its nuclear localization. The importance of LCK in CCA biology was demonstrated by clinical observations suggesting LCK expression levels were associated with early tumor recurrence following resection of CCA. Finally, dasatinib displayed therapeutic efficacy in PDX models. .

The Hippo pathway effector YAP is implicated in the pathogenesis of cholangiocarcinoma (CCA). The Hippo pathway relies on signaling cross talk for its regulation. Given the importance of platelet derived growth factor receptor (PDGFR) signaling in CCA biology, our aim was to examine potential YAP regulation by PDGFR. We employed human and mouse CCA specimens and cell lines for these studies. Initially, we confirmed upregulation of PDGFRβ and PDGFR ligands in human and mouse CCA specimens and cell lines. YAP, a transcriptional co-activator, was localized to the nucleus in human CCA specimens and a cell line, as well as patient derived xenografts (PDX). PDGFR pharmacologic inhibition led to a

Adenosquamous cancer of the pancreas (ASCP) is a subtype of pancreatic cancer that has a worse prognosis and greater metastatic potential than the more common pancreatic ductal adenocarcinoma (PDAC) subtype. To distinguish the genomic landscape of ASCP and identify actionable targets for this lethal cancer, we applied DNA content flow cytometry to a series of 15 tumor samples including five patient-derived xenografts (PDX). We interrogated purified sorted tumor fractions from these samples with whole-genome copy-number variant (CNV), whole-exome sequencing, and Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) analyses. These identified a variety of somatic genomic lesions targeting chromatin regulators in ASCP genomes that were superimposed on wellcharacterized genomic lesions including mutations in TP53 (87%) and KRAS (73%), amplification of MYC (47%), and homozygous deletion of CDKN2A (40%) that are common in PDACs. Furthermore, a comparison of ATAC-seq profiles of three ASCP and three PDAC genomes using flow-sorted PDX models identified genes with accessible chromatin unique to the ASCP genomes, including the lysine methyltransferase SMYD2 and the pancreatic cancer stem cell regulator RORC in all three ASCPs, and a FGFR1-ERLIN2 fusion associated with focal CNVs in both genes in a single ASCP. Finally, we demonstrate significant activity of a pan FGFR inhibitor against organoids derived from the FGFR1-ERLIN2 fusion-positive ASCP PDX model. Our results suggest that the genomic and epigenomic landscape of ASCP provide new strategies for targeting this aggressive subtype of pancreatic cancer. Significance: These data provide a unique description of the ASCP genomic and epigenomic landscape and identify candidate therapeutic targets for this dismal cancer.

Despite socioeconomic status and country of origin, patients from more rural environments demonstrate poorer outcomes notwithstanding significant differences in overall disease severity. The AAST grading system may serve a potential benchmark to recognize areas with disparate disease burdens. This information could be used for strategic improvements for surgeon placement and availability.