Increased YAP Expression Research Articles

MST1 down-regulation in decreasing apoptosis of aortic dissection smooth muscle cell apoptosis.

Elevated apoptosis of vascular smooth muscle cell (VSMC) is correlated with the occurrence of aortic dissection (AD). Mammalian ste20-like protein kinase 1 (MST1) is one important component of Hippo-YAP signal pathway for activation and cell apoptosis facilitation. Whether MST1 plays a role in AD pathogenesis is unclear yet. This study established an AD rat model to investigate the role of MST1 in regulating VSMC apoptosis and AD pathogenesis. Cell apoptosis was compared between AD vascular tissues and normal rats, in addition to Caspase-3 activity, and expression of MST1, p-LATS1, p-YAP1, YAP1. In vitro cultured VSMCs from AD rats were treated with siRNA-MST1 to test apoptotic rate and Caspase-3 activity. AD model rats were treated with pGLVU6/GFP-MST1 for comparing MST1, p-LATS1, p-YAP1, and YAP1 expression, along with Caspase-3 activity, cell apoptosis, AD formation rate, diameter, and length. Compared to control group, AD rats had elevated vascular cell apoptosis, Caspase-3 activity, expressions of MST1, p-LATS1, and p-YAP1, plus lower YAP1 expression. siRNA interference of MST1 significantly inhibited apoptosis of in vitro cultured VSMC. shRNA lentivirus targeting MST1 pGLVU6/GFP-MST1 remarkably decreased expression of MST1, p-LATS1, and p-YAP1 in AD rat vascular tissues, increased YAP1 expression, decreased VSMC apoptosis, AD formation rate, AD diameter/length. MST1 up-regulation plays a role in facilitating VSMC apoptosis and AD pathogenesis. Down-regulation of MST1 decreased VSMC apoptosis and AD formation.

LncRNA UCA1 promotes migration and invasion in pancreatic cancer cells via the Hippo pathway

Although overexpression of the long non-coding RNA (lncRNA) UCA1 has been implicated in several human cancers, its biological function in pancreatic cancer remains to be clarified. In this study, we reported that UCA1 expression was significantly increased in pancreatic cancer tissues and correlated with clinicopathological features, tumor stage, and poorer patient outcome. We further showed that UCA1 promoted cell migration and invasion of pancreatic cancer cells. Importantly, we found that UCA1 overexpression inhibited YAP phosphorylation, and increased YAP expression. Mechanistically, UCA1 interacted with MOB1, Lats1, and YAP, forming shielding composites. Moreover, we demonstrated that UCA1 increased YAP nuclear localization and stabilization, and improved TEAD luciferase activity. In turn, YAP promotes UCA1 expression. Collectively, the present study provides insights into the mechanistic regulation of UCA1 promoting pancreatic cancer progression through the Hippo signaling pathway. UCA1 may serve as a candidate biomarker for poor prognosis and a target for new pancreatic cancer therapies.

Role of Yes-associated protein 1 in angiotensinⅡ-induced pulmonary fibrosis in rats

Objective: To explore the mechanism of Yes-associated protein 1 (Yap1) in angiotensinⅡ(AngⅡ)-induced pulmonary fibrosis. Methods:In vivo, 18 male Wistar rats were randomly divided into three equal groups with 6 rats in each group, including control group, bleomycin-treated group (BLM), and BLM+ AngⅡ group. 28 days later, the lung tissues in all groups were harvested for the HE and Masson staining as well as the immunohistochemical (IHC) staining for Yap1. In vitro, the isolated fibroblasts were treated with 10(-7) mmol/L AngⅡor the AngⅡ-targeted inhibitor irbesartan for the scheduled time for mRNA and protein expressions of Yap1, PDZ-binding motif (TAZ), and collagen Ⅰusing PCR and Western blot, as well as the translocation test from the nucleus to the cytoplasm of Yap1 and TAZ. Subsequently, the fibroblasts were assigned into 4 groups: the empty plasmid (vector) group, the vector+ AngⅡ group, the Yap1 shRNA group, and the Yap1 shRNA+ AngⅡ group. Western blot was used to detect the relative expressions of Yap1, TAZ, Smad3 and collagen Ⅰ. The CCK-8 and EdU assays were performed to determine the proliferative capacity. Results:In vivo, severe lung fibrosis and increased Yap1 expression of IHC staining were found in BLM group. Additionally, more severe lung fibrosis and higher Yap1 expression were detected in the BLM+ AngⅡ group than the BLM group (both P<0.05). In vitro, both the mRNA and protein relative expressions of Yap1, TAZ and collagenⅠ were markedly higher in AngⅡ-treated groups than the control group (all P<0.05). Meanwhile, the relative expression of phosphorylated Yap1 reached its peak at 2 h after AngⅡ stimulation. In the protein translocation tests, after treated with AngⅡ for 24 h, the relative protein levels of Yap1 and TAZ in the nucleus of the AngⅡ group were significantly higher than those in the control group (0.382±0.007 vs 0.031±0.001, 1.097±0.030 vs 0.357±0.015). However, the relative protein expressions in the cytoplasm of the AngⅡ group were obviously less than that in the control group (0.323±0.058 vs 0.418±0.044, 0.858±0.059 vs 1.201±0.015). Compared with the AngⅡ group, the expressions of Yap1 and TAZ in the AngⅡ+ irbesartan group were higher in cytoplasm (0.598±0.060 vs 0.323±0.058, 1.495±0.052 vs 0.858±0.059), while lower in the nucleus (0.323±0.058 vs 0.418±0.044, 0.858±0.059 vs 1.201±0.015) (all P<0.05). Furthermore, the relative protein expressions of Yap1, TAZ, Smad3 and collagenⅠin Yap1 shRNA+ AngⅡ group were distinctly lower than the vector+ AngⅡ group (all P<0.05). In the cell proliferation tests, the absorbance and the percentage of EdU positive cells of vector+ AngⅡ group exceeded that of vector group (both P<0.05). However, the absorbance and the percentage of EdU positive cells in the Yap1 shRNA+ AngⅡgroup were less than the vector+ AngⅡ group (both P<0.05). Conclusion: AngiotensinⅡ promoted the collagen synthesis and cell proliferation in primary lung fibroblasts by increasing the Yap1 activity, leading to the progress of fibrosis.

Ovatodiolide suppresses colon tumorigenesis and prevents polarization of M2 tumor-associated macrophages through YAP oncogenic pathways

BackgroundAn increased expression of Yes-associated protein (YAP1) has been shown to promote tumorigenesis in many cancer types including colon. However, the role of YAP1 in promoting colon tumorigenesis remains unclear. Here, we demonstrate that YAP1 expression is associated with M2 tumor-associated macrophage polarization and the generation of colon cancer stem-like cells. YAP1 downregulation by gene silencing or a phytochemical, ovatodiolide, not only suppresses colon cancer tumorigenesis but also prevents M2 TAM polarization.MethodsHuman monocytic cells, THP-1, and colon cancer cell lines, HCT116 and DLD-1, were co-cultured to mimic the interactions between tumor and its microenvironment. M2 polarization of the THP-1 cells were examined using both flow cytometry and q-PCR technique. The inhibition of YAP1 signaling was achieved by gene-silencing technique or ovatodiolide. The molecular consequences of YAP1 inhibition was demonstrated via colony formation, migration, and colon-sphere formation assays. 5-FU and ovatodiolide were used in drug combination studies. Xenograft and syngeneic mouse models were used to investigate the role of YAP1 in colon tumorigenesis and TAM generation.ResultsAn increased YAP1 expression was found to be associated with a poor prognosis in patients with colon cancer using bioinformatics approach. We showed an increased YAP1 expression in the colon spheres, and colon cancer cells co-cultured with M2 TAMs. YAP1-silencing led to the concomitant decreased expression of major oncogenic pathways including Kras, mTOR, β-catenin, and M2-promoting IL-4 and tumor-promoting IL-6 cytokines. TAM co-cultured colon spheres showed a significantly higher tumor-initiating ability in vivo. Ovatodiolide treatment alone and in combination with 5-FU significantly suppressed in vivo tumorigenesis and less TAM infiltration in CT26 syngeneic mouse model.ConclusionsWe have identified the dual function of YAP1 where its suppression not only inhibited tumorigenesis but also prevented the generation of cancer stem-like cells and M2 TAM polarization. Ovatodiolide treatment suppressed YAP1 oncogenic pathways to inhibit colon tumorigenesis and M2 TAM generation both in vitro and in vivo. Ovatodiolide should be considered for its potential for adjuvant therapeutic development.

A cell-autonomous tumour suppressor role of RAF1 in hepatocarcinogenesis.

Hepatocellular carcinoma (HCC) is a leading cause of cancer deaths, but its molecular heterogeneity hampers the design of targeted therapies. Currently, the only therapeutic option for advanced HCC is Sorafenib, an inhibitor whose targets include RAF. Unexpectedly, RAF1 expression is reduced in human HCC samples. Modelling RAF1 downregulation by RNAi increases the proliferation of human HCC lines in xenografts and in culture; furthermore, RAF1 ablation promotes chemical hepatocarcinogenesis and the proliferation of cultured (pre)malignant mouse hepatocytes. The phenotypes depend on increased YAP1 expression and STAT3 activation, observed in cultured RAF1-deficient cells, in HCC xenografts, and in autochthonous liver tumours. Thus RAF1, although essential for the development of skin and lung tumours, is a negative regulator of hepatocarcinogenesis. This unexpected finding highlights the contribution of the cellular/tissue environment in determining the function of a protein, and underscores the importance of understanding the molecular context of a disease to inform therapy design.

Hippo pathway effector YAP inhibition restores the sensitivity of EGFR-TKI in lung adenocarcinoma having primary or acquired EGFR-TKI resistance

The efficacy of EGFR-tyrosine kinase inhibitors (TKIs) is significantly limited by various resistance mechanisms to those drugs. The resistance to EGFR-TKI is largely divided by two classes; acquired resistance after EGFR-TKI treatment, and primary resistance marked by cancer cell's dependence on other oncogene, such as KRAS. YAP has emerged as critical oncogene in conferring drug resistance against targeted therapy. In this study, we evaluated the role of YAP in primary and acquired EGFR-TKI resistance using gefitinib-resistant A549 and PC9 cells and their parental cell lines. Our study revealed that EGFR-TKI resistance is associated with enhanced YAP activity. Notably, YAP activation was independent of the Hippo pathway. We confirmed that AXL is a downstream target of YAP that confers EGFR-TKI resistance. And our results showed that YAP can induce ERK activation in lung adenocarcinoma. The combination of YAP inhibition with EGFR-TKI overcomes primary and acquired EGFR-TKI resistance. We also found increased YAP expression in human lung cancer after acquiring EGFR-TKI resistance. Collectively, we suggest a novel EGFR-TKI resistance mechanism involving YAP activation and suggest targeting YAP and EGFR simultaneously may be a breakthrough treatment of primary and acquired EGFR-TKI resistant lung cancer.