RNA-binding protein QKI regulates contact inhibition via Yes-associate protein in ccRCC

Contact inhibition adjusts organ size to the proper size and ensures the cultured cells growing to a monolayer.By regulating the downstream coordinator YAP,the evolutionarily conserved Hippo transduction pathway attunes cell growth and death in response to cell contact inhibition,polarity,self-renewal,and differentiation.Dysregulation of this pathway is involved in various diseases such as cancer.RNA-binding protein QKI regulates cell proliferation,metabolism,division,and immunity in various cancer models,but its role in cancer cell contact inhibition remains unclear.In this study,we aimed to clarify the relationship between QKI and YAP,and the role of their interaction in cell contact inhibition.We found a lower QKI expression level in sparse condition,whereas a higher expression level in confluent condition by western blot analysis and immunofluorescence assay.QKI knockdown elevated cell proliferation and invasion both in vitro and in vivo.Strikingly,the results of CCK-8 assay,colony formation assay,and transwell assay showed that the phenomenon was in accord with the expression level of pYAP and reverse with YAP.Higher levels of Wnt3a and β-catenin were also found in xenografts of QKI-knockdown clear cell renal cell carcinoma (ccRCC) CAKI-1 cells by western blot analysis and immumohistochemical staining.Finally,a positive correlation between QKI and pYAP was found in clinical specimens by immunohistochemistry.Thus,as a negative regulator of YAP,QKI attuned the cell contact inhibition,leading to inhibition of cancer cell proliferation and invasion through Wnt and GPCR pathway.     

The coiled-coil domain containing protein Ccdc136b antagonizes maternal Wnt/β-catenin activity during zebrafish dorsoventral axial patterning

The coiled-coil domain containing protein CCDC136 is a putative tumor suppressor and significantly down-regulated in gastric and colorectal cancer tissues.However,little is known about its biological functions during vertebrate embryo development.Zebrafish has two CCDC136 orthologs,ccdcl36 a and ccdc136 b,but only ccdc136 b is highly expressed during early embryonic development.In this study,we demonstrate that ccdc136 b is required for dorsal-ventral axial patterning in zebrafish embryos.ccdc136 b morphants display strongly dorsalized phenotypes.Loss- and gain-of-function experiments in zebrafish embryos and mammalian cells show that Ccdc136 b is a crucial negative regulator of the Wnt/β-catenin signaling pathway,and plays a critical role in the establishment of the dorsal-ventral axis.We further find that Ccdc136 b interacts with APC,promotes the binding affinity of APC with β-catenin and then facilitates the turnover of β-catenin.These results provide the first evidence that CCDC136 regulates zebrafish dorsal-ventral patterning by antagonizing Wnt/β-catenin signal transduction and suggest a potential mechanism underlying its suppressive activity in carcinogenesis.     

Expression and function of leptin and its receptor in mouse mammary gland

Leptin is an autocrine and paracrine factor which affects the development of duct, formation of gland alveolus, expression of milk protein gene and onset involution of mammary gland. In order to know the function and mechanism of leptin in mammary gland, the protein expression and localization of leptin and its long form receptor (OB-Rb) were detected by a confocal laser scanning microscope. To study the impacts of leptin on mammary gland and leptin signal transduction pathway in pregnancy-, lacta-tion-and involution-stage mammary gland, explants were cultured and Western blotting was used. The results showed that in the whole development cycle of mammary gland, the expression of leptin and OB-Rb was in positive correlation. In virgin the leptin expression was the highest and then decreased in pregnancy. In lactation the expression of leptin was low and upgraded in involution, and recovered to the original level about virgin on involution 13 d. The localization of leptin and OB-Rb revealed that leptin induced the expression of OB-Rb specifically and controlled the development and physiological function of the mammary gland by binding to OB-Rb. In pregnancy stage, leptin stimulated proliferation and differentiation of ductal epithelial cells by JAK-MAPK signal pathway. In lactation, leptin induced gene expression of β-casein by JAK-STAT5 signal pathway, and in involution leptin induced mammary epithelial cell apoptosis and mammary gland restitution by JAK-STAT3 signal pathway.     

β-catenin is up-expressed and predicts poor overall survival of breast cancer

Breast cancer (BC) is one of the most common malignant tumors in women.The majority of BC cells contain at least one or more up-expressed oncogene. β-catenin is found overexpressed in various epithelial cell cancers and has the function of inducing cancer cell proliferation, invasion and metastasis. However, the expression of β-catenin and its prognostic value in BC is not yet clear. In this study, mRNA and β-catenin proteins expressed in BC tissues have been explored. Quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC) on tissue microarrays (TMA) were performed to examine the level of β-catenin mRNA and protein in BC tissues. The association between β-catenin and clinical characteristics and prognostic value were also explored. β-catenin mRNA and protein were found over-expressed in BC tissues when compared with matched tumor neighbor tissues. A high degree of β-catenin staining in BC tissues was significantly associated with tumor size, Ki67 expression, lymph node status and TNM stage. β-catenin up-expression was also able to predict poor overall survival (OS) rates. These results indicated that β-catenin may be a useful prognostic molecular biomarker for BC patients.     

Extracellular O-linked β-N-acetylglucosamine: Its biology and relationship to human disease

The O-linked β-N-acetylglucosamine(O-GlcNAc)ylation of cytoplasmic and nuclear proteins regulates basic cellular functions and is involved in the etiology of neurodegeneration and diabetes. Intracellular O-GlcNAcylation is catalyzed by a single O-GlcNAc transferase, O-GlcNAc transferase(OGT). Recently, an atypical O-GlcNAc transferase, extracellular O-linked β-N-acetylglucosamine(EOGT), which is responsible for the modification of extracellular O-GlcNAc, was identified. Although both OGT and EOGT are regulated through the common hexosamine biosynthesis pathway, EOGT localizes to the lumen of the endoplasmic reticulum and transfers GlcNAc to epidermal growth factor-like domains in an OGT-independent manner. In Drosophila, loss of Eogt gives phenotypes similar to those caused by defects in the apical extracellular matrix. Dumpy, a membrane-anchored apical extracellular matrix protein, was identified as a major O-GlcNAcylated protein, and EOGT mediates Dumpy-dependent cell adhesion. In mammals, extracellular O-GlcNAc was detected on extracellular proteins including heparan sulfate proteoglycan 2, Nell1, laminin subunit alpha-5, Pamr1, and transmembrane proteins, including Notch receptors. Although the physiological function of O-GlcNAc in mammals has not yet been elucidated, exome sequencing identified homozygous EOGT mutations in patients with Adams-Oliver syndrome, a rare congenital disorder characterized by aplasia cutis congenita and terminal transverse limb defects. This review summarizes the current knowledge of extracellular O-GlcNAc and its implications in the pathological processes in Adams-Oliver syndrome.     

TRIM29 prevents hepatocellular carcinoma progression by inhibiting Wnt/β-catenin signaling pathway

TRIM29 plays an important role in many neoplasms.In this study,we aimed to elucidate its role in hepatocellular carcinoma (HCC) and explore the corresponding potential mechanism.The expression level of TRIM29 in HCC samples and hepatoma cell lines was detected.We found that TRIM29 was down-regulated in clinical HCC samples and cultured hepatoma cell lines by western blot analysis and quantitative polymerase chain reaction.In addition,we demonstrated that higher TRIM29 expression was associated with higher differentiation grade of HCC.To explore the effect of TRIM29 on hepatoma cells and its possible mechanisms,TRIM29-knockdown and overexpression cell models were constructed.The results showed that the depletion of TRIM29 promoted liver cancer cell proliferation,clone formation,migration and invasion in vitro probably through the Wnt/β-catenin signaling pathway.This study revealed the inhibitory roles of TRIM29 in HCC and the possible mechanisms.