Background & Aims Cancer cells often lose contact inhibition to undergo anchorage-independent proliferation and become resistant to apoptosis by inactivating the Hippo signaling pathway, resulting in activation of the transcriptional co-activator yes-associated protein (YAP). However, the oncogenic mechanisms of YAP are unclear. Methods Using cross-species analysis of expression data, the Notch ligand Jagged-1 (Jag-1) was identified as downstream target of YAP in hepatocytes and hepatocellular carcinoma (HCC) cells. We analyzed the functions of YAP in HCC cells via overexpression and RNA silencing experiments. We used transgenic mice that overexpressed a constitutively activated form of YAP (YAPS127A), and measured protein levels in HCC and colorectal and pancreatic tumor samples from patients. Results Human HCC cell lines and mouse hepatocytes that overexpress YAPS127A upregulated Jag-1, leading to activation of the Notch pathway and increased proliferation. Induction of Jag-1, activation of Notch, and cell proliferation required binding of YAP to its transcriptional partner TEAD4; TEAD4 binding required Mst1/2, but not WNT-β-catenin signaling. Levels of YAP correlated with Jag-1 expression and Notch signaling in human tumor samples and shorter survival times of patients with HCC or colorectal cancer. Conclusion The transcriptional regulator YAP upregulates Jag-1 to activate Notch signaling in HCC cells and mouse hepatocytes. YAP-dependent activity of Jag-1 and Notch correlate in human HCC and colorectal tumor samples with patient survival times, suggesting the use of YAP and Notch inhibitors as therapeutics for gastrointestinal cancer.

Background: Success of chemotherapy and alleviation of pain are frequently less than optimal in pancreatic cancer patients, leading to increasing interest in new pharmacological substances, such as vanilloids. Our study addressed the question of whether vanilloids influence pancreatic cancer cell growth, and if vanilloids could be used for pain treatment via the vanilloid 1 receptor (VR1) in pancreatic cancer patients. Methods: In vitro, the effect of resiniferatoxin (vanilloid analogue) on apoptosis and cell growth in pancreatic cancer cells-either alone, combined with 5-fluorouracil (5-FU), or combined with gemcitabine-was determined by annexin V staining, FACS analysis, and MTT assay, respectively. VR1 expression was evaluated on RNA and protein level by quantitative polymerase chain reaction and immunohistochemistry in human pancreatic cancer and chronic pancreatitis. Patient characteristicsespecially pain levels-were registered in a prospective database and correlated with VR1 expression. Results: Resiniferatoxin induced apoptosis by targeting mitochondrial respiration and decreased cell growth in pancreatic cancer cells without showing synergistic effects with 5-FU or gemcitabine. Expression of VR1 was significantly upregulated in human pancreatic cancer and chronic pancreatitis. VR1 expression was related to the intensity of pain reported by cancer patients but not to the intensity of pain reported by patients with chronic pancreatitis. Conclusions: Resiniferatoxin induced apoptosis in pancreatic cancer cells indicates that vanilloids may be useful in the treatment of human pancreatic cancer. Furthermore, vanilloid might be a novel and effective treatment option for neurogenic pain in patients with pancreatic cancer.

PCa is associated with a specific decrease of distinct serum proteins, which allows a reliable differentiation between pancreatic cancer and healthy controls.

Purpose: Mass spectrometry-based serum peptidome profiling is a promising tool to identify novel disease-associated biomarkers, but is limited by preanalytic factors and the intricacies of complex data processing. Therefore, we investigated whether standardized sample protocols and new bioinformatic tools combined with external data validation improve the validity of peptidome profiling for the discovery of pancreatic cancerassociated serum markers. Experimental Design: For the discovery study, two sets of sera from patients with pancreatic cancer (n = 40) and healthy controls (n = 40) were obtained from two different clinical centers. For external data validation, we collected an independent set of samples from patients (n = 20) and healthy controls (n = 20). Magnetic beads with different surface functionalities were used for peptidome fractionation followed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). Data evaluation was carried out by comparing two different bioinformatic strategies. Following proteome database search, the matching candidate peptide was verified by MALDI-TOF MS after specific antibody-based immunoaffinity chromatography and independently confirmed by an ELISA assay. Results: Two significant peaks (m/z 3884; 5959) achieved a sensitivity of 86.3% and a specificity of 97.6% for the discrimination of patients and healthy controls in the external validation set. Adding peak m/z 3884 to conventional clinical tumor markers (CA 19-9 and CEA) improved sensitivity and specificity, as shown by receiver operator characteristics curve analysis (AUROC combined = 1.00). Mass spectrometry-based m/z 3884 peak identification and following immunologic quantitation revealed platelet factor 4 as the corresponding peptide. Conclusions: MALDI-TOF MS-based serum peptidome profiling allowed the discovery and validation of platelet factor 4 as a new discriminating marker in pancreatic cancer.