Lifu Wang

Sp1 upregulates expression of TRF2 and TRF2 inhibition reduces tumorigenesis in human colorectal carcinoma cells.

Telomeres are essential for the maintenance of genomic integrality, they enable complete DNA replication, organize subnuclear domains, and protect chromosome ends against fusion. Loss of telomere function in human cells results in the formation of dicentric chromosomes and other abnormalities such as end-to-end fusions.TRF2 is a ubiquitously expressed protein which binds directly to the tandem array of duplex telomeric repeats and is involved in the telomere structure and chromosome end protection. Inhibition of TRF2 induces end-to-end chromosome fusions and growth arrest or apoptosis in human melanoma cells.Lack of TRF2 in ALT cells also caused PMLdependent p53 activation and loss of telomeric DNA.TRF2 over-expression is found in several human tumors such as breast carcinomas, liver hepatocarcinomas, lung carcinomas and gastric carcinomas. This suggests that TRF2 may have a role in tumorigenisis.Cancers of the gastrointestinal tract share numerous common genetic features despite differing widely in incidence and outcome.However, the role and mechanisms that lead to over-expressed TRF2 in colorectal carcinoma are not well known. Sp1 is a member of the multigene family with sequence-specific DNA-binding C-terminal zinc-finger motifs, which plays a critical role in the regulation of expression of mammalian genes lacking a TATA box, by binding to GC/GT boxes to activate transcription.Cancer-related Sp1 targets include PDEGF, p21, VEGF, TGF-β, cyclin D1, E2F1, c-fos, transforming growth factor α and osteopontin (OPN).The promoter of TRF2 is GC-rich sequence (70-75%), which lacks an obvious TATA box. It is unclear whether or not TRF2 is regulated via Sp1, which may in turn be regulated to genomic stability. We tested the expression of TRF2 in colorectal carcinoma tissues and colon carcinoma SW480 cell line, and studied the role of Sp1 in regulating TRF2 expression in colon carcinoma. Results showed that TRF2 was over-expressed in colorectal carcinoma tissues and SW480 cell line. It was also shown that Sp1 transcription factor is involved in the up-regulation of TRF2 expression.

The biological features of PanIN initiated from oncogenic Kras mutation in genetically engineered mouse models.

Pancreatic intraepithelial neoplasia (PanIN) is the most common premalignant lesion of the pancreas. Further understanding of the biological behavior and molecular genetic alterations in the stepwise progression of PanINs is necessary toward the development of pancreatic ductal adenocarcinoma (PDAC) interventions. In this study, we analyzed the morphological characteristics, molecular alterations, and biological behavior of pancreatic wild-type and neoplasia tissues, including analysis of PanIN cell line SH-PAN (isolated from Pdx-1-Cre; LSL-KrasG12D/+ mouse) and PDAC cell line DT-PCa (isolated from Pdx1-Cre; LSL-KrasG12D/+; LSL-Tp53R172H/+ mouse. Results show that KrasG12D induces ductal lesion PanINs. Increased expression of EGFR, Her-2/Neu, p-MAPK and β-Catenin was observed in low-grade PanINs. Tp53 was not expressed in wild-type and low-grade PanINs, however, increased expression was observed in high-grade PanINs. Furthermore, SH-PAN cells did not exhibit any colony formation and showed significantly lower migration and invasion ability compared with DT-PCa cells. Notably, we first found PPP2R2A (protein phosphatase 2, regulatory subunit B, alpha) expression was significantly higher in SH-PAN cells than DT-PCa cells, and was high in 96 of 172 peritumoral normal human pancreatic tissues and 20 of 36 human low- or middle-grade PanIN tissues, whereas, was weak or negligible in 12 of 20 human high-grade PanIN tissues and 124 of 172 human PDAC tissues post-operation. The expression of PPP2R2A appears to be correlated with clinical survival. Taken together, Kras(G12D) - driven PanIN showed the tumorigenic ability, however, did not undergo a malignant transformation, and decreased expression of PPP2R2A in PDACs may provided a new target for pancreatic carcinoma intervention.

Complimentary Imaging Modalities for Investigating Obscure Gastrointestinal Bleeding: Capsule Endoscopy, Double-Balloon Enteroscopy, and Computed Tomographic Enterography

Objectives. The complimentary value of computed tomographic enterography (CTE) and double-balloon enteroscopy (DBE) combined with capsule endoscopy (CE) was evaluated in the diagnosis of obscure gastrointestinal bleeding (OGIB). Methods. Patients who received CE examinations at Ruijin Hospital between July 2007 and July 2014 with the indication of OGIB were identified, and those who also underwent DBE and/or CTE were included. Their clinical information was retrieved, and results from each test were compared with findings from the other two examinations. Results. The overall diagnostic yield of CE was comparable with DBE (73.9% versus 60.9%) but was significantly higher than the yield of CTE (87% versus 25%, p < 0.001). The diagnostic yield of angiodysplasia at CE was significantly higher than CTE (73% versus 8%, p < 0.001) and DBE (39.1% versus 17.4%, p = 0.013), while no significant difference was found between the three approaches for small bowel tumors. DBE and CTE identified small bowel diseases undetected or undetermined by CE. Conversely, CE improved diagnosis in the cases with negative CTE and DBE, and findings at initial CE directed further diagnosis made by DBE. Conclusions. Combination of the three diagnostic platforms provides complementary value in the diagnosis of OGIB.

Smad4-dependent suppressor pituitary homeobox 2 promotes PPP2R2A-mediated inhibition of Akt pathway in pancreatic cancer

The importance of Pituitary homeobox 2 (Pitx2) in malignancy remains enigmatic, and Pitx2 has not been previously implicated in pancreatic ductal adenocarcinoma (PDAC). In this study, we performed gene expression profiling of human PDAC tissues and identified Pitx2 as a promising candidate. Pitx2 expression was decreased from 2.6- to 19-fold in human PDAC tissues from microarray units. Immunochemistry staining showed that Pitx2 expression was moderate to intense in normal pancreatic and pancreatic intraepithelial neoplastic lesions, whereas low in human PDAC tissues. The Pitx2 levels correlated with overall patient survival post-operatively in PDAC. Induction of Pitx2 expression partly inhibited the malignant phenotype of PDAC cells. Interestingly, low Pitx2 expression was correlated with Smad4 mutant inactivation, but not with Pitx2 DNA-methylation. Furthermore, Smad4 protein bound to Pitx2 promoter and stimulated Pitx2 expression in PDAC. In addition, Pitx2 protein bound to the promoter of the protein phosphatase 2A regulatory subunit B55α (PPP2R2A) and upregulated PPP2R2A expression, which may activate dephosphorylation of Akt in PDAC. These findings provide new mechanistic insights into Pitx2 as a tumor suppressor in the downstream of Smad4. And Pitx2 protein promotes PPP2R2A expression which may inhibit Akt pathway. Therefore, we propose that the Smad4-Pitx2-PPP2R2A axis, a new signaling pathway, suppresses the pancreatic carcinogenesis.

BRCA2 Dysfunction Promotes Malignant Transformation of Pancreatic Intraepithelial Neoplasia

Pancreatic ductal adenocarcinoma (PDAC) is an almost lethal disease. Thus, it is important to better understand its genetic progression from normal cells through precancerous lesions pancreatic intraepithelial neoplasia (PanIN) to invasive pancreatic cancer. Carriers of a germline mutation in BRCA2 have an increased risk of developing PDAC when compared with the general population. The purpose of our study was to examine the role of BRCA2 dysfuction in the progression of PDAC. Here we generated a novel in vitro model of pancreatic carcinogenesis. Cancerous PanIN-BR1 cells were established by stable transduction with lentiviral-mediated BRCA2 RNA interference in PanIN cell isolated from mice with oncogenic KrasG12D. Our data showed that silencing of BRCA2 promoted cell proliferation, migration and invasion in vitro. The tumorigenic potential of PanIN-BR1 were assessed by xenograft tumor formation in BALB/c nude mice. The expression of PCNA , Snail and Slug in the tumor xenografts was detected by immunohistochemistry. The staining for PCNA, Snail and Slug in PanIN-BR1-formed xenograft tissue was significantly more intense than PanIN-formed xenograft tissue. Microarray assay was also performed. Based on gene expression profiling and further validation by real-time PCR and Western Blot, we found that the expression of Cyclinb2, Cyclina2, Twist1, Wisp1 and Cxcr4 revealed a significant increase in the PanIN-BR1 cells, however, the expression of p15, p16 and Wisp2 showed a significant decrease in the PanIN-BR1 cells, compared to the PanIN cells. Collectively, these data reported here demonstrate that BRCA2 may be a promising therapeutic targets for PDAC progression.

Niacin ameliorates ulcerative colitis via prostaglandin D2‐mediated D prostanoid receptor 1 activation

Niacin, as an antidyslipidemic drug, elicits a strong flushing response by release of prostaglandin (PG) D2. However, whether niacin is beneficial for inflammatory bowel disease (IBD) remains unclear. Here, we observed niacin administration‐enhanced PGD2 production in colon tissues in dextran sulfate sodium (DSS)‐challenged mice, and protected mice against DSS or 2,4,6‐trinitrobenzene sulfonic acid (TNBS)‐induced colitis in D prostanoid receptor 1 (DP1)‐dependent manner. Specific ablation of DP1 receptor in vascular endothelial cells, colonic epithelium, and myeloid cells augmented DSS/TNBS‐induced colitis in mice through increasing vascular permeability, promoting apoptosis of epithelial cells, and stimulating pro‐inflammatory cytokine secretion of macrophages, respectively. Niacin treatment improved vascular permeability, reduced apoptotic epithelial cells, promoted epithelial cell update, and suppressed pro‐inflammatory gene expression of macrophages. Moreover, treatment with niacin‐containing retention enema effectively promoted UC clinical remission and mucosal healing in patients with moderately active disease. Therefore, niacin displayed multiple beneficial effects on DSS/TNBS‐induced colitis in mice by activation of PGD2/DP1 axis. The potential efficacy of niacin in management of IBD warrants further investigation.

Exploring the Wnt Pathway-Associated LncRNAs and Genes Involved in Pancreatic Carcinogenesis Driven by Tp53 Mutation

ABSTRACTPurposeStudy the contribution of long non-coding RNAs (lncRNAs) to progression of pancreatic intraepithelial neoplasia (PanIN) to pancreatic ductal adenocarcinoma (PDAC).MethodsWe explored lncRNAs profilings in PanIN cell line (SH-PAN) isolated from Pdx-1-Cre; LSL-KrasG12D/+ mice and PDAC cell line (DT-PCa) isolated from Pdx-1-Cre; LSL- KrasG12D/+; LSL- Tp53R172H/+ mice by lncRNAs microarray, and detected expression of lncRNAs and genes in PDAC by Real-time PCR, Western blot, ChIP and immunohistochemistry.ResultsEight lncRNAs and five protein-coding genes, associated with Wnt pathway, were identified with more than five-fold changes between DT-PCa cells and SH-PAN cells. Of them, lincRNA1611 and Ppp3ca were validated significantly high expression in DT-PCa cells and in 22 of 26 fresh resected human PDAC tissues, compared to SH-PAN cells and normal pancreatic tissues, respectively. Moreover, Tp53 mutation status displayed a positive correlation with lincRNA1611 or Ppp3ca level. Immunohistochemical staining for Ppp3ca was weak or lack in 91 of 107 normal pancreatic tissues, 24 of 29 PanIN-I and 13 of 16 PanIN-II tissues, however, was strong in 10 of 27 PanIN-III and 62 of 107 PDAC tissues post operation.ConclusionsLincRNA1611 and Ppp3ca were high expression in PDAC and may serve as new potential targets for intervention of the disease.

Combination of Five Body Positions Can Effectively Improve the Rate of Gastric Mucosa’s Complete Visualization by Applying Magnetic-Guided Capsule Endoscopy

Objectives. Achieving a comprehensive view of gastric mucosa has been a challenge for magnetic-guided capsule endoscopy (MGCE) for years. This study works on optimizing the performance of MGCE by changing the conventional positions to the five body positions. Methods. Sixty patients were enrolled in the study and underwent MGCE. All patients were asked to adopt five body positions (left lateral, supine, right lateral, knee-chest, and sitting). In each position, the ability to visualize the six gastric landmarks (cardia, fundus, body, angulus, antrum, and pylorus) was assessed. Rates of complete visualization were calculated for different position combinations. Results. Supine position was the best for cardia and body visualization (91.7% and 86.7%, resp., p < 0.001). Left lateral position was the best for fundus visualization (91.7%, p < 0.001). Knee-chest position was the best for angulus observation (80.0%, p < 0.001). Right lateral and sitting positions were the best for antrum observation (88.3% and 90.0%, resp., p < 0.001). Right lateral position was the best for pylorus observation (81.7%, p < 0.001). The supine + right lateral + knee-chest combination achieved better angulus visualization than conventional 3-position combination (93.3% versus 63.3%, p < 0.001). Five-position combination significantly improved the comprehensive gastric landmark visualization (93.3%, p < 0.001). Conclusion. Compared with 3-position combination, 5-position combination should be adopted for gastric mucosal visualization by MGCE.

EI24 Suppresses Tumorigenesis in Pancreatic Cancer via Regulating c-Myc

The EI24 autophagy-associated transmembrane protein is frequently associated with tumor growth and patient survival. In the present study, we found that EI24 was downregulated in pancreatic ductal adenocarcinoma (PDAC) tissues compared with adjacent normal tissues and was associated with cancer cell differentiation. Overexpression of EI24 suppressed cancer cell growth in vitro and in vivo and induced cell cycle S phase arrest, with no impact on caspase-dependent apoptosis. EI24 overexpression also resulted in reduced c-Myc expression, an oncogene in PDAC, accompanied with increased LC3B-II formation, increased Beclin-1, and diminished p62. Together, we propose that EI24 suppresses cell proliferation and prompts cell cycle arrest in pancreatic cancer cells by activating the autophagic lysosomal degradation of c-Myc. Our results suggest a potential mechanism underlying the antitumor effects of EI24 in PDAC and provide insight into the crosstalk between autophagy and cell proliferation involving a possible EI24/Beclin-1/p62/c-Myc signaling pathway.

Magnetic-Guided Capsule Endoscopy in the Diagnosis of Gastrointestinal Diseases in Minors

Objective This study aimed at investigating the clinical value of magnetic-guided capsule endoscopy (MGCE) in the diagnosis of gastrointestinal diseases in minors. Methods Eighty-four minor patients hospitalized in the pediatric department at Ruijin Hospital between June 2015 and January 2018 were enrolled for this study. Following bowel preparation, all patients underwent MGCE. The feasibility, safety, diagnostic yield, and sensitivity of MGCE were analyzed. Patients were followed up for more than 2 weeks. Results The main indications for MGCE in minors were Crohns disease, gastrointestinal bleeding, and abdominal pain. The main causes of gastric disease were gastric inflammatory hyperplasia, exudative gastritis, and polyps. The most common small bowel diseases in minors were Crohns disease, Henoch-Schonlein purpura, and polyps. The diagnostic yield in the stomach and small intestine was 13.1% and 28.6%, respectively, and the sensitivity was 100% and 96.0%, respectively. No adverse events occurred. Conclusion MGCE is a safe, effective, and well-tolerated procedure with good sensitivity and has a potential clinic value for the diagnosis of gastrointestinal diseases in minors.