GATA6 Activates Wnt Signaling in Pancreatic Cancer by Negatively Regulating the Wnt Antagonist Dickkopf-1

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease characterized by late diagnosis and treatment resistance. Recurrent genetic alterations in defined genes in association with perturbations of developmental cell signaling pathways have been associated with PDAC development and progression. Here, we show that GATA6 contributes to pancreatic carcinogenesis during the temporal progression of pancreatic intraepithelial neoplasia by virtue of Wnt pathway activation. GATA6 is recurrently amplified by both quantitative-PCR and fluorescent in-situ hybridization in human pancreatic intraepithelial neoplasia and in PDAC tissues, and GATA6 copy number is significantly correlated with overall patient survival. Forced overexpression of GATA6 in cancer cell lines enhanced cell proliferation and colony formation in soft agar in vitro and growth in vivo, as well as increased Wnt signaling. By contrast siRNA mediated knockdown of GATA6 led to corresponding decreases in these same parameters. The effects of GATA6 were found to be due to its ability to bind DNA, as forced overexpression of a DNA-binding mutant of GATA6 had no effects on cell growth in vitro or in vivo, nor did they affect Wnt signaling levels in these same cells. A microarray analysis revealed the Wnt antagonist Dickopf-1 (DKK1) as a dysregulated gene in association with GATA6 knockdown, and direct binding of GATA6 to the DKK1 promoter was confirmed by chromatin immunoprecipitation and electrophoretic mobility shift assays. Transient transfection of GATA6, but not mutant GATA6, into cancer cell lines led to decreased DKK1 mRNA expression and secretion of DKK1 protein into culture media. Forced overexpression of DKK1 antagonized the effects of GATA6 on Wnt signaling in pancreatic cancer cells. These findings illustrate that one mechanism by which GATA6 promotes pancreatic carcinogenesis is by virtue of its activation of canonical Wnt signaling via regulation of DKK1

Clinicopathologic and Genetic Characterization of Traditional Serrated Adenomas of the Colon

Traditional serrated adenomas (TSAs) are a type of colorectal polyp with neoplastic potential. Immunohistochemical analysis and sequencing were performed on 24 TSAs from 23 patients to characterize the molecular genetics of TSAs. Abnormal Ki-67 and p53 labeling were observed in 7 (29%) of 24 and 6 (25%) of 24 TSAs, respectively; both types were significantly associated with the presence of conventional epithelial dysplasia (P = .0005 and P = .0001, respectively). Activating KRAS mutation was identified in 11 TSAs (46%) and was mutually exclusive with activating BRAF mutations, which were seen in 7 TSAs (29%). Abnormal p53 nuclear labeling in a TSA was significantly associated with BRAF mutation status (P = .04), whereas no relationship was found for β-catenin labeling patterns. The overall morphologic features of TSA do not correlate with the genetic status of the KRAS and BRAF genes. However, conventional epithelial dysplasia and abnormal p53 labeling in a TSA are seen more often in the setting of BRAF mutation

Analysis on the Standardized Expression of the Accredited Ability Scope for Hematology, Blood Biochemistry and Urinalysis in Laboratory Animal Clinical Testing

To improve the application of hematology and urine testing of laboratory animals, and the consistency and effectiveness of the on-site review in China, there is a need for further standardization of the expression of testing ability in this field. In addition, it promotes better understanding and acceptance of the China National Accreditation Service for Conformity Assessment (CNAS) recognized results by relevant parties. In this paper, the expression of the accredited competence scope in the domestic and international institutes of laboratory animal hematology, blood biochemistry, and urine analysis fields were analyzed and compared. This study provides the CNAS with recommendations to standardize the expression of accreditation ability. In addition, it provides a detailed theoretical reference for further improving the process of standardizing testing of laboratory animals in China

Supplementary Online Material

The description of measurements of piezoelectric surface layers and strain state near surface, and an estimation of flexoelectric field Table S1 Fig. S1-S9</p

Accumulated chromosomal instability in murine bone marrow mesenchymal stem cells leads to malignant transformation

Despite recent emerging evidence suggesting that cancer stem cells subsist in a variety of tumors, it is not yet fully elucidated whether postnatal stem cells are directly involved in tumorigenesis. We used murine bone marrow-derived mesenchymal stem cells (BMMSCs) as a model to test a hypothesis that tumorigenesis may originate from spontaneous mutation of stem cells. In this study, we demonstrated that murine BMMSCs, after numerous passages, obtained unlimited population doublings and proceeded to a malignant transformation state, resulting in fibrosarcoma formation in vivo. Transformed BMMSCs colonized to multiple organs when delivered systemically through the tail vein. Fibrosarcoma cells formed by transformed BMMSCs contained cancer progenitors, which were capable of generating colony clusters in vitro and fibrosarcoma in vivo by the second administration. The mechanism by which BMMSCs transformed to malignant cells was associated with accumulated chromosomal abnormalities, gradual elevation in telomerase activity, and increased c-myc expression. Moreover, BMMSCs and their transformed counterpart, fibrosarcoma-forming cells, demonstrated different sensitivity to anti-cancer drugs. BMMSCs/fibrosarcoma transformation system may provide an ideal system to elucidate the mechanism of how stem cells become cancer cells and to screen anti-sarcoma drugs

Stress Responsive Proteins Are Actively Regulated during Rice (<i>Oryza sativa</i>) Embryogenesis as Indicated by Quantitative Proteomics Analysis

<div><p>Embryogenesis is the initial step in a plant’s life, and the molecular changes that occur during embryonic development are largely unknown. To explore the relevant molecular events, we used the isobaric tags for relative and absolute quantification (iTRAQ) coupled with the shotgun proteomics technique (iTRAQ/Shotgun) to study the proteomic changes of rice embryos during embryogenesis. For the first time, a total of 2 165 unique proteins were identified in rice embryos, and the abundances of 867 proteins were actively changed based on the statistical evaluation of the quantitative MS/MS signals. The quantitative data were then confirmed using multiple reactions monitoring (MRM) and were also supported by our previous study based on two-dimensional gel electrophoresis (2 DE). Using the proteome at 6 days after pollination (DAP) as a reference, cluster analysis of these differential proteins throughout rice embryogenesis revealed that 25% were up-regulated and 75% were down-regulated. Gene Ontology (GO) analysis implicated that most of the up-regulated proteins were functionally categorized as stress responsive, mainly including heat shock-, lipid transfer-, and reactive oxygen species-related proteins. The stress-responsive proteins were thus postulated to play an important role during seed maturation.</p></div