Lipophilic statins inhibit YAP coactivator transcriptional activity in HCC cells through Rho-mediated modulation of actin cytoskeleton.

Hepatocellular carcinoma (HCC) is the third leading cause of liver-related death. Lipophilic statins have been associated with a decrease in HCC incidence, raising the possibility of their use as chemoprevention agents. The Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) have emerged as an important pro-oncogenic mechanism in HCC.

Lipophilic Statins Inhibit YAP Nuclear Localization, Coactivator Activity, and Migration in Response to Ligation of HLA Class I Molecules in Endothelial Cells: Role of YAP Multisite Phosphorylation.

Solid-organ transplant recipients exhibiting HLA donor-specific Abs are at risk for graft loss due to chronic Ab-mediated rejection. HLA Abs bind HLA molecules expressed on the surface of endothelial cells (ECs) and induce intracellular signaling pathways, including the activation of the transcriptional coactivator yes-associated protein (YAP). In this study, we examined the impact of lipid-lowering drugs of the statin family on YAP localization, multisite phosphorylation, and transcriptional activity in human ECs.

Opposite Effects of Src Family Kinases on YAP and ERK Activation in Pancreatic Cancer Cells: Implications for Targeted Therapy.

Pancreatic ductal adenocarcinoma (PDAC) remains an aggressive disease that is expected to become the second cause of cancer fatalities during the next decade. As therapeutic options are limited, novel targets, and agents for therapeutic intervention are urgently needed. Previously, we identified potent positive crosstalk between insulin/IGF-1 receptors and G protein-coupled (GPCR) signaling systems leading to mitogenic signaling in PDAC cells.

Ligation of HLA Class I Molecules Induces YAP Activation through Src in Human Endothelial Cells.

Ab cross-linking of HLA class I (HLA I) molecules on the surface of endothelial cells (EC) triggers proliferative and prosurvival intracellular signaling, which is implicated in the process of chronic allograft rejection, also known as transplant vasculopathy. Despite the importance of Ab-mediated rejection in transplantation, the mechanisms involved remain incompletely understood. In this study, we examined the regulation of yes-associated protein (YAP) localization, phosphorylation, and transcriptional activity in human ECs challenged with Abs that bind HLA I.

Lipophilic statins inhibit YAP nuclear localization, co-activator activity and colony formation in pancreatic cancer cells and prevent the initial stages of pancreatic ductal adenocarcinoma in KrasG12D mice.

We examined the impact of statins on Yes-associated Protein (YAP) localization, phosphorylation and transcriptional activity in human and mouse pancreatic ductal adenocarcinoma (PDAC) cells. Exposure of sparse cultures of PANC-1 and MiaPaCa-2 cells to cerivastatin or simvastatin induced a striking re-localization of YAP from the nucleus to the cytoplasm and inhibited the expression of the YAP/TEAD-regulated genes Connective Tissue Growth Factor (CTGF) and Cysteine-rich angiogenic inducer 61 (CYR61). Statins also prevented YAP nuclear import and expression of CTGF and CYR61 stimulated by the mitogenic combination of insulin and neurotensin in dense culture of these PDAC cells.

Yes-associated protein (YAP) in pancreatic cancer: at the epicenter of a targetable signaling network associated with patient survival.

Pancreatic ductal adenocarcinoma (PDAC) is generally a fatal disease with no efficacious treatment modalities. Elucidation of signaling mechanisms that will lead to the identification of novel targets for therapy and chemoprevention is urgently needed. Here, we review the role of Yes-associated protein (YAP) and WW-domain-containing Transcriptional co-Activator with a PDZ-binding motif (TAZ) in the development of PDAC.

Metformin Decreases the Incidence of Pancreatic Ductal Adenocarcinoma Promoted by Diet-induced Obesity in the Conditional KrasG12D Mouse Model.

Pancreatic ductal adenocarcinoma (PDAC) is a particularly deadly disease. Chronic conditions, including obesity and type-2 diabetes are risk factors, thus making PDAC amenable to preventive strategies. We aimed to characterize the chemo-preventive effects of metformin, a widely used anti-diabetic drug, on PDAC development using the Kras mouse model subjected to a diet high in fats and calories (HFCD).

Incidence of pancreatic cancer is dramatically increased by a high fat, high calorie diet in KrasG12D mice.

Epidemiologic data has linked obesity to a higher risk of pancreatic cancer, but the underlying mechanisms are poorly understood. To allow for detailed mechanistic studies in a relevant model mimicking diet-induced obesity and pancreatic cancer, a high-fat, high-calorie diet (HFCD) was given to P48+/Cre;LSL-KRASG12D (KC) mice carrying a pancreas-specific oncogenic Kras mutation. The mice were randomly allocated to a HFCD or control diet (CD).

Protein kinase D1 (PKD1) phosphorylation on Ser by type I p21-activated kinase (PAK) regulates PKD1 localization.

Although PKC-mediated phosphorylation of protein kinase D1 (PKD1) has been extensively characterized, little is known about PKD1 regulation by other upstream kinases. Here we report that stimulation of epithelial or fibroblastic cells with G protein-coupled receptor agonists, including angiotensin II or bombesin, induced rapid and persistent PKD1 phosphorylation at Ser, a highly conserved residue located within the PKD1 N-terminal domain. Exposure to PKD or PKC family inhibitors did not prevent PKD1 phosphorylation at Ser, indicating that it is not mediated by autophosphorylation.

Insulin Receptor and GPCR Crosstalk Stimulates YAP via PI3K and PKD in Pancreatic Cancer Cells.

We examined the impact of crosstalk between the insulin receptor and G protein-coupled receptor (GPCR) signaling pathways on the regulation of Yes-associated protein (YAP) localization, phosphorylation, and transcriptional activity in the context of human pancreatic ductal adenocarcinoma (PDAC). Stimulation of PANC-1 or MiaPaCa-2 cells with insulin and neurotensin, a potent mitogenic combination of agonists for these cells, promoted striking YAP nuclear localization and decreased YAP phosphorylation at Ser and Ser Challenging PDAC cells with either insulin or neurotensin alone modestly induced the expression of YAP/TEAD-regulated genes, including connective tissue growth factor (), cysteine-rich angiogenic inducer 61 (), and , whereas the combination of neurotensin and insulin induced a marked increase in the level of expression of these genes. In addition, siRNA-mediated knockdown of YAP/TAZ prevented the increase in the expression of these genes.

Direct growth-inhibitory effects of prostaglandin E2 in pancreatic cancer cells in vitro through an EP4/PKA-mediated mechanism.

Background: There is strong evidence linking inflammation and the development of pancreatic ductal adenocarcinoma. Cyclooxygenase-2 (COX-2) and COX-2-derived PGE are overexpressed in human and murine pancreatic ductal adenocarcinoma. Several studies have demonstrated an important role of COX-2-derived PGE in tumor-stroma interactions; however, the direct growth effects of prostaglandin E (PGE) on pancreatic ductal adenocarcinoma cells is less well defined.

Biphasic Regulation of Yes-associated Protein (YAP) Cellular Localization, Phosphorylation, and Activity by G Protein-coupled Receptor Agonists in Intestinal Epithelial Cells: A NOVEL ROLE FOR PROTEIN KINASE D (PKD).

We examined the regulation of Yes-associated protein (YAP) localization, phosphorylation, and transcriptional activity in intestinal epithelial cells. Our results show that stimulation of intestinal epithelial IEC-18 cells with the G protein-coupled receptor (GPCR) agonist angiotensin II, a potent mitogen for these cells, induced rapid translocation of YAP from the nucleus to the cytoplasm (within 15 min) and a concomitant increase in YAP phosphorylation at Ser(127) and Ser(397) Angiotensin II elicited YAP phosphorylation and cytoplasmic accumulation in a dose-dependent manner (ED50 = 0.3 nm).

Positive cross talk between protein kinase D and β-catenin in intestinal epithelial cells: impact on β-catenin nuclear localization and phosphorylation at Ser552.

Given the fundamental role of β-catenin signaling in intestinal epithelial cell proliferation and the growth-promoting function of protein kinase D1 (PKD1) in these cells, we hypothesized that PKDs mediate cross talk with β-catenin signaling. The results presented here provide several lines of evidence supporting this hypothesis. We found that stimulation of intestinal epithelial IEC-18 cells with the G protein-coupled receptor (GPCR) agonist angiotensin II (ANG II), a potent inducer of PKD activation, promoted endogenous β-catenin nuclear localization in a time-dependent manner.

Prostaglandin E2 activates the mTORC1 pathway through an EP4/cAMP/PKA- and EP1/Ca2+-mediated mechanism in the human pancreatic carcinoma cell line PANC-1.

Obesity, a known risk factor for pancreatic cancer, is associated with inflammation and insulin resistance. Proinflammatory prostaglandin E2 (PGE2) and elevated insulin-like growth factor type 1 (IGF-1), related to insulin resistance, are shown to play critical roles in pancreatic cancer progression. We aimed to explore a potential cross talk between PGE2 signaling and the IGF-1/Akt/mammalian target of rapamycin complex 1 (mTORC1) pathway in pancreatic cancer, which may be a key to unraveling the obesity-cancer link.

Dose-Dependent AMPK-Dependent and Independent Mechanisms of Berberine and Metformin Inhibition of mTORC1, ERK, DNA Synthesis and Proliferation in Pancreatic Cancer Cells.

Natural products represent a rich reservoir of potential small chemical molecules exhibiting anti-proliferative and chemopreventive properties. Here, we show that treatment of pancreatic ductal adenocarcinoma (PDAC) cells (PANC-1, MiaPaCa-2) with the isoquinoline alkaloid berberine (0.3-6 µM) inhibited DNA synthesis and proliferation of these cells and delay the progression of their cell cycle in G1.

Protein kinase D1 mediates class IIa histone deacetylase phosphorylation and nuclear extrusion in intestinal epithelial cells: role in mitogenic signaling.

We examined whether class IIa histone deacetylases (HDACs) play a role in mitogenic signaling mediated by protein kinase D1 (PKD1) in IEC-18 intestinal epithelial cells. Our results show that class IIa HDAC4, HDAC5, and HDAC7 are prominently expressed in these cells. Stimulation with ANG II, a potent mitogen for IEC-18 cells, induced a striking increase in phosphorylation of HDAC4 at Ser(246) and Ser(632), HDAC5 at Ser(259) and Ser(498), and HDAC7 at Ser(155).

Intracellular Ca2+ oscillations generated via the Ca2+-sensing receptor are mediated by negative feedback by PKCα at Thr888.

To clarify the mechanism(s) underlying intracellular Ca(2+) concentration ([Ca(2+)]i) oscillations induced by an elevation in extracellular Ca(2+) concentration ([Ca(2+)]e) via the extracellular Ca(2+)-sensing receptor (CaR), we analyzed the pattern of [Ca(2+)]i response in multiple (2,303) individual HEK-293 cells transfected with the human CaR. An increase in the [Ca(2+)]e from 1.5 to 3 mM produced oscillatory fluctuations in [Ca(2+)]i in 70% of the cell population.

PKD1 mediates negative feedback of PI3K/Akt activation in response to G protein-coupled receptors.

We examined whether protein kinase D1 (PKD1) mediates negative feeback of PI3K/Akt signaling in intestinal epithelial cells stimulated with G protein-coupled receptor (GPCR) agonists. Exposure of intestinal epithelial IEC-18 cells to increasing concentrations of the PKD family inhibitor kb NB 142-70, at concentrations that inhibited PKD1 activation, strikingly potentiated Akt phosphorylation at Thr(308) and Ser(473) in response to the mitogenic GPCR agonist angiotensin II (ANG II). Enhancement of Akt activation by kb NB 142-70 was also evident in cells with other GPCR agonists, including vasopressin and lysophosphatidic acid.

TNF-α and LPA promote synergistic expression of COX-2 in human colonic myofibroblasts: role of LPA-mediated transactivation of upregulated EGFR.

Background: Enhanced EGF receptor (EGFR) signaling is a hallmark of many human cancers, though the role of enhanced EGFR signaling within the surrounding tumor stroma has not been well studied. The myofibroblast is an important stromal cell that demonstrates enhanced EGFR expression in the setting of inflammation, though the functional relevance is not known. We recently reported that TNF-α and the G protein-coupled receptor (GPCR) agonist lysophosphatidic acid (LPA) lead to synergistic cyclo-oxygenase-2 (COX-2) expression, an enzyme strongly associated with the development of colitis-associated cancer.

Metformin inhibits the growth of human pancreatic cancer xenografts.

Objective: Pancreatic ductal adenocarcinoma is a devastating disease, with an overall 5-year survival rate of only 3% to 5%. As the current therapies offer very limited survival benefits, novel therapeutic strategies are urgently required to treat this disease. Here, we determined whether metformin administration inhibits the growth of PANC-1 and MiaPaCa-2 tumor xenografts in vivo.

Different patterns of Akt and ERK feedback activation in response to rapamycin, active-site mTOR inhibitors and metformin in pancreatic cancer cells.

The mTOR pathway is aberrantly stimulated in many cancer cells, including pancreatic ductal adenocarcinoma (PDAC), and thus it is a potential target for therapy. However, the mTORC1/S6K axis also mediates negative feedback loops that attenuate signaling via insulin/IGF receptor and other tyrosine kinase receptors. Suppression of these feed-back loops unleashes over-activation of upstream pathways that potentially counterbalance the antiproliferative effects of mTOR inhibitors.