Post-translational deregulation of YAP1 is genetically controlled in rat liver cancer and determines the fate and stem-like behavior of the human disease

Previous studies showed that YAP1 is over-expressed in hepatocellular carcinoma (HCC). Here we observed higher expression of Yap1/Ctgf axis in dysplastic nodules and HCC chemically-induced in F344 rats, genetically susceptible to hepatocarcinogenesis, than in lesions induced in resistant BN rats. In BN rats, highest increase in Yap1-tyr357, p73 phosphorylation and Caspase 3 cleavage occurred. In human HCCs with poorer prognosis ( 3 years survival; HCCB). In the latter, higher levels of phosphorylated YAP1-ser127, YAP1-tyr357 and p73, YAP1 ubiquitination, and Caspase 3 cleavage occurred. Expression of stemness markers NANOG, OCT-3/4, and CD133 were highest in HCCP and correlated with YAP1 and YAP1-TEAD levels. In HepG2, Huh7, and Hep3B cells, forced YAP1 over-expression led to stem cell markers expression and increased cell viability, whereas inhibition of YAP1 expression by specific siRNA, or transfection of mutant YAP1 which does not bind to TEAD, induced opposite alterations. These changes were associated, in Huh7 cells transfected with YAP1 or YAP1 siRNA, with stimulation or inhibition of cell migration and invasivity, respectively. Furthermore, transcriptome analysis showed that YAP1 transfection in Huh7 cells induces over-expression of genes involved in tumor stemness. In conclusion, Yap1 post-translational modifications favoring its ubiquitination and apoptosis characterize HCC with better prognosis, whereas conditions favoring the formation of YAP1-TEAD complexes are associated with aggressiveness and acquisition of stemness features by HCC cells

Increased expression of YAP1 in prostate cancer correlates with extraprostatic extension.

Objective:Yes associated protein 1 (YAP1) is a member of the Hippo pathway, acting as a transcriptional coactivator. To elucidate the role of YAP1 and phosphorylated (p)YAP1 in prostate cancer (PCa) tumorigenesis, we investigated their expression in clinical samples of PCa and cell lines. Methods:Fifty-four tumor, adjacent nontumor, and prostate intraepithelial neoplasia (PIN) tissues from patients with PCa after radical prostatectomy were selected from a retrospective cohort and studied using immunohistochemistry (IHC). Protein and mRNA expression levels of YAP1 were evaluated by Western blot analysis and quantitative real-time reverse transcription PCR, respectively, in cancer cell lines. Publicly available gene expression datasets were downloaded to analyze YAP1 mRNA and protein levels in PCa tissue samples. Results:IHC analysis of PCa tissues revealed that YAP1 staining intensities were moderate to weak in the nucleus and cytoplasm of tumor cells, whereas adjacent normal epithelia showed strong staining. We observed that benign prostates were characterized by higher expression levels of both nuclear (P=0.004) and cytosolic (P=0.005) YAP1. pYAP1 staining was weak in the cytoplasm and absent in the nucleus of all the tissues investigated. YAP1 expression was an indicator of extraprostatic extension (EPE). The level of YAP1 was negatively correlated with the level of the androgen receptor (AR) in The Cancer Genome Atlas dataset and Western blot analysis of cell lines. Conclusions:Our study suggested that YAP1 expression is heterogeneous in PCa tissue samples; therefore, YAP1 might play different roles in different aspects of PCa progression. This might involve AR-YAP1 interplay in PCa

RGC1/RGC2 deletions cause increased sensitivity to oxidative stress in Saccharomyces cerevisiae, which can be overcome by constitutive nuclear Yap1 expression

Oxidative stress mechanism in yeast presents an innovative pathway to understand in creating the next generation of antifungal drugs. Rgc1 and Rgc2 are paralogous proteins that regulate the Fps1 glycerol channel in hyperosmotic stress. Hyperosmotic conditions lead Hog1 MAP kinase to phosphorylate Rgc2 and cause its dissociation from Fps1, allowing the channel to close and protect the cell from damage. Rgc2 contains pleckstrin homology (PH) domains broken up by long insertions and more phosphorylation sites than targeted by Hog1 in response to hyperosmotic stress. Since none of the other MAP kinases in yeast were seen to phosphorylate Rgc2 during oxidative stress, it is thought that Rgc2 may bind to other proteins. In this study, the sensitivity of a strain deleted for both RGC1 and RGC2 was compared to strains with single deletions in either gene in response to oxidative stress. Having deletions in both RGC1 and RGC2 caused increased sensitivity to hydrogen peroxide whereas strains with deletions in either gene seemed unaffected, correlating with the fact that Rgc1 and Rgc2 are paralogous proteins, able to recover each other's functions. A second analysis compared mutated Fps1 (fps1∆-FKSV) and a strain with deletions for both RGC1 and RGC2 (rgc1/2∆). The fps1∆-FKSV strain has four amino acid substitutions in the C-terminal region where Rgc2 binds to Fps1. While both strains grew less than wild-type in hydrogen peroxide, the rgc1/2∆ strain was more sensitive suggesting that Rgc1/2 has an additional role in oxidative stress. To identify the oxidative stress function of Rgc1/2, a genomic overexpression library was transformed into the rgc1/2∆ strain and used for a suppressor screen in the presence of hydrogen peroxide. Although the screen revealed a manageable amount of 49 candidates, only four produced sequences that spanned a protein-encoding region. The candidate plasmids were transformed back into the rgc1/2∆ strain for preparation of a sensitivity assay which showed that the colonies did not survive any better than the starting rgc1/2∆ strain. Without a plausible plasmid candidate, we decided to look into the effect of YAP1 on the rgc1/2∆ strain. Yap1 is a transcription factor known to activate many genes in oxidative stress. Two forms of YAP1 were transformed into rgc1/2∆: wild-type YAP1 and YAP1-A627E which contains a mutation in the nuclear export signal. Compared to the controls, YAP1-A627E allowed the rgc1/2∆ strain to grow at 1.5mM H2O2 while wild-type YAP1 did not. This result showed that a constitutively nuclear Yap1 can overcome deletions in RGC1 and RGC2. It also suggested that an increased activity in the nucleus was important in hydrogen peroxide resistance and another suppressor screen of rgc1/2∆ was performed looking for spontaneous mutations in the genomic DNA. The screened colonies were tested for their survival on hydrogen peroxide but their resistance appeared to be transient. We have shown Rgc1 and Rgc2 to be important cellular components in oxidative stress in addition to hyperosmotic stress. Further research on Rgc1/2 would provide invaluable knowledge on oxidative stress protection in yeast and a better foundation on which to build antifungal drugs

Genomic, Pathway Network, and Immunologic Features Distinguishing Squamous Carcinomas

This integrated, multiplatform PanCancer Atlas study co-mapped and identified distinguishing molecular features of squamous cell carcinomas (SCCs) from five sites associated with smokin

TEAD and YAP regulate the enhancer network of human embryonic pancreatic progenitors.

The genomic regulatory programmes that underlie human organogenesis are poorly understood. Pancreas development, in particular, has pivotal implications for pancreatic regeneration, cancer and diabetes. We have now characterized the regulatory landscape of embryonic multipotent progenitor cells that give rise to all pancreatic epithelial lineages. Using human embryonic pancreas and embryonic-stem-cell-derived progenitors we identify stage-specific transcripts and associated enhancers, many of which are co-occupied by transcription factors that are essential for pancreas development. We further show that TEAD1, a Hippo signalling effector, is an integral component of the transcription factor combinatorial code of pancreatic progenitor enhancers. TEAD and its coactivator YAP activate key pancreatic signalling mediators and transcription factors, and regulate the expansion of pancreatic progenitors. This work therefore uncovers a central role for TEAD and YAP as signal-responsive regulators of multipotent pancreatic progenitors, and provides a resource for the study of embryonic development of the human pancreas