Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with poor survival rates and frequently carries oncogenic KRAS mutation. However, KRAS has thus far not been a viable therapeutic target. We found that the abundance of YAP mRNA, which encodes Yes-associated protein (YAP), a protein regulated by the Hippo pathway during tissue development and homeostasis, was increased in human PDAC tissue compared with that in normal pancreatic epithelia. In genetically engineered KrasG12D and KrasG12D: Trp53R172H mouse models, pancreas-specific deletion of Yap halted the progression of early neoplastic lesions to PDAC without affecting normal pancreatic development and endocrine function. Although Yap was dispensable for acinar to ductal metaplasia (ADM), an initial step in the progression to PDAC, Yap was critically required for the proliferation of mutant Kras or Kras:Trp53 neoplastic pancreatic ductal cells in culture and for their growth and progression to invasive PDAC in mice. Yap functioned as a critical transcriptional switch downstream of the oncogenic KRAS–mitogen-activated protein kinase (MAPK) pathway, promoting the expression of genes encoding secretory factors that cumulatively sustained neoplastic proliferation, a tumorigenic stromal response in the tumor microenvironment, and PDAC progression in Kras and Kras: Trp53 mutant pancreas tissue. Together, our findings identified Yap as a critical oncogenic KRAS effector and a promising therapeutic target for PDAC and possibly other types of KRAS-mutant cancers.

Gallic acid is widely distributed in plants, fruits and foods with a range of biological activities. In the present study the possible mechanisms of gallic acid anticancer properties were explored in A549, a human lung adenocarcinoma cell line. Our study shows that it inhibited the A549 cell growth and decreased cell viability monitored at 24 h. It also inhibited cell proliferation in dose- and time-dependent manner as measured by 3-[4,5-methylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide assay at 24 and 48 h. Morphological examination of the cells after gallic acid treatment showed the typical feature of cell death such as cell shrinkage and rounding up of the cells. Clonogenic assay indicated that gallic acid treatments inhibited the colony formation. DNA fragmentation assay indicated the disappearance of the genomic DNA in dose-dependent manner. To find out possible mechanisms, mitochondrial potential and intracellular reactive oxygen species were measured. It was observed that gallic acid treatment decreased mitochondrial membrane potential and increased intracellular reactive oxygen species. Further caspases activity was measured and it was found that gallic acid activated the caspase-3 but not caspase-8 indicating the involvement of intrinsic pathway of cell apoptosis.