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Eradicating influenza A virus (IAV) is difficult, due to its genetic drift and reassortment ability. As the infectious cycle is initiated by the influenza glycoprotein, hemagglutinin (HA), which mediates the binding of virions to terminal sialic acids moieties, HA is a tempting target of anti-influenza inhibitors. However, the complexity of the HA structure has prevented delineation of the structural characterization of the HA protein–ligand complex. Our computational strategy efficiently analyzed > 200,000 records of compounds held in the United States National Cancer Institute (NCI) database and identified potential HA inhibitors, by modeling the sialic acid (SA) receptor binding site (RBS) for the HA structure. Our modeling revealed that compound NSC85561 showed significant antiviral activity against the IAV H1N1 strain with EC50 values ranging from 2.31 to 2.53 µM and negligible cytotoxicity (CC50 > 700 µM). Using the NSC85561 compound as the template to generate 12 derivatives, robust bioassay results revealed the strongest antiviral efficacies with NSC47715 and NSC7223. Virtual screening clearly identified three SA receptor binding site inhibitors that were successfully validated in experimental data. Thus, our computational strategy has identified SA receptor binding site inhibitors against HA that show IAV-associated antiviral activity.

BackgroundBidirectional integrin αIIbβ3 signaling is essential for platelet activation. The platelet adaptor protein Disabled-2 (Dab2) is a key regulator of integrin signaling and is phosphorylated at serine 24 in eukaryotic cells. However, the mechanistic insight and function of Dab2-serine 24 phosphorylation (Dab2-pSer24) in platelet biology are barely understood. This study aimed to define whether and how Dab2 is phosphorylated at Ser24 during platelet activation and to investigate the effect of Dab2-pSer24 on platelet function.ResultsAn antibody with confirmed specificity for Dab2-pSer24 was generated. By using this antibody as a tool, we showed that protein kinase C (PKC)-mediated Dab2-pSer24 was a conservative signaling event when human platelets were activated by the platelet agonists such as thrombin, collagen, ADP, 12-O-tetradecanoylphorbol-13-acetate, and the thromboxane A2 activator U46619. The agonists-stimulated Dab2-pSer24 was attenuated by pretreatment of platelets with the RGDS peptide which inhibits integrin outside-in signaling by competitive binding of integrin αIIb with fibrinogen. Direct activation of platelet integrin outside-in signaling by combined treatment of platelets with manganese dichloride and fibrinogen or by spreading of platelets on fibrinogen also resulted in Dab2-pSer24. These findings implicate that Dab2-pSer24 was associated with the outside-in signaling of integrin. Further analysis revealed that Dab2-pSer24 was downstream of Src-PKC-axis and phospholipase D1 underlying the integrin αIIbβ3 outside-in signaling. A membrane penetrating peptide R11-Ser24 which contained 11 repeats of arginine linked to the Dab2-Ser24 phosphorylation site and its flanking sequences (RRRRRRRRRRR19APKAPSKKEKK29) and the R11-S24A peptide with Ser24Ala mutation were designed to elucidate the functions of Dab2-pSer24. R11-Ser24 but not R11-S24A inhibited agonists-stimulated Dab2-pSer24 and consequently suppressed platelet spreading on fibrinogen, with no effect on platelet aggregation and fibrinogen binding. Notably, Ser24 and the previously reported Ser723 phosphorylation (Dab2-pSer723) occurred exclusively in a single Dab2 molecule and resulted in distinctive subcellular distribution and function of Dab2. Dab2-pSer723 was mainly distributed in the cytosol of activated platelets and associated with integrin inside-out signaling, while Dab2-pSer24 was mainly distributed in the membrane fraction of activated platelets and associated with integrin outside-in signaling.ConclusionsThese findings demonstrate for the first time that Dab2-pSer24 is conservative in integrin αIIbβ3 outside-in signaling during platelet activation and plays a novel role in the control of cytoskeleton reorganization and platelet spreading on fibrinogen.

Hepatitis C virus (HCV) infection of hepatocytes promotes liver fibrosis by activation of hepatic stellate cells (HSCs) and excessive deposition of extracellular matrix in liver tissue. Whether or not host factors released from the HCV-infected hepatocytes play role in HSCs activation is unclear. In this study, HSCs were activated by the conditioned medium derived from HCV replicon cells. Secretomic profiling of HCV replicon cells and the parental Huh7 cells revealed ubiquitin carboxy-terminal hydrolase L1 (UCHL1) as a novel secreted protein from HCV-infected hepatocytes. UCHL1 expression in hepatocytes was induced by HCV infection. UCHL1 was expressed in the liver and found in the plasma of patients with chronic hepatitis C. Molecular analysis by use of the anti-UCHL1 neutralization antibody and purified UCHL1 protein showed that secreted UCHL1 protein was bound to the cell surface of HSCs and activated JNK signaling leading to overexpression of alpha-smooth muscle actin and the activation of HSCs. These results provide further for understanding the underlying mechanism in HCV-mediated hepatic fibrogenesis.

Hepatitis C virus (HCV) nonstructural protein 5B (NS5B) is an RNA-dependent RNA polymerase (RdRp) that acts as a key player in the HCV replication complex. Understanding the interplay between the viral and cellular components of the HCV replication complex could provide new insight for prevention of the progression of HCV-associated hepatocellular carcinoma (HCC). In this study, the NS5B protein was used as the bait in a pulldown assay to screen for NS5B-interacting proteins that are present in Huh7 hepatoma cell lysates. After mass spectrophotometric analysis, fatty acid synthase (FASN) was found to interact with NS5B. Coimmunoprecipitation and double staining assays further confirmed the direct binding between NS5B and FASN. The domain of NS5B that interacts with FASN was also determined. Moreover, FASN was associated with detergent-resistant lipid rafts and colocalized with NS5B in active HCV replication complexes. In addition, overexpression of FASN enhanced HCV expression in Huh7/Rep-Feo cells, while transfection of FASN small interfering RNA (siRNA) or treatment with FASN-specific inhibitors decreased HCV replication and viral production. Notably, FASN directly increased HCV NS5B RdRp activity in vitro . These results together indicate that FASN interacts with NS5B and modulates HCV replication through a direct increase of NS5B RdRp activity. FASN may thereby serve as a target for the treatment of HCV infection and the prevention of HCV-associated HCC progression.

Ethnopharmacological evidence Gexia-Zhuyu Tang (GZT), also called Gexiazhuyu decoction (GXZYD), is a traditional Chinese herbal medicine for chronic liver diseases such as cirrhosis and liver fibrosis. Aim of the study In this study, we have investigated the affects of GZT on a rat model of dimethylnitrosamine (DMN)-induced liver fibrosis. Materials and methods In this study, the protective effects of GZT on DMN-induced liver fibrosis were measured using a rat model. Following 5 weeks of DMN-treatment (8 mg/kg, i.p., given 3 consecutive days each week), oral administration of GZT at 1.8 g/kg daily via oral gavage for 2 weeks beginning at week 13. Results Both body and liver weights were significantly decreased. The reductions in body and liver weights corresponded with increasing liver damage severity. Furthermore, GZT-treatment remarkably decreased the levels of serum GOT (glutamate oxaloacetate transaminase) and GPT (glutamic pyruvic transaminase), and the mRNA expression levels of collagen alpha- 1( I ) and alpha-smooth muscle actin ( alpha-SMA ) in DMN-induced hepatic fibrosis. In addition, hepatic stellate cells (HSCs) play a major role in various types of liver fibrosis through initial myofibroblast transformation. The proliferation of HSCs was inhibited by GZT. Treatment with GZT also induced HSC apoptosis in a dose- and time-dependent manner. GZT treatment induced HSC apoptosis by facilitating Ca 2+ release from the mitochondria within 6 h. Subsequently, caspases 3 and 12 were elevated by 72 h after treatment. Conclusions Our studies indicate that GZT exhibited both hepatoprotective and antifibrogenic effects in DMN-induced hepatic injury. These findings suggest that GZT may be useful in preventing the development of hepatic fibrosis.

Patients with thyroid cancer usually have good prognosis. However, 15-20% of patients ultimately develop recurrence and disease-related death. In this study, we investigate whether the number of circulating tumor cells (CTCs) expressing either epithelial cell adhesion molecule (EpCAM), podoplanin (PDPN, a marker related to poor prognosis in patients with thyroid cancer), or thyroid-stimulating hormone receptor (TSHR, a marker for thyroid cells) is a prognostic marker for non-remission and disease-specific mortality (DSM) of patients with thyroid cancer. Blood samples were collected from patients (n = 128) after thyroidectomy or radioactive iodide therapy. After enrichment of CTCs by a negative selection PowerMag system, enumeration and subtyping of the CD45-depleted cells were performed by immunofluorescence staining using the antibodies aginst EpCAM, TSHR, and PDPN, respectively. Our data revealed that the number of EpCAM+-CTCs (p < 0.001) and PDPN+-CTCs (p < 0.001), and TSHR+-CTCs (p < 0.001) for patients in the non-remission group (n = 43) was significantly higher when compared to the remission group (n = 85). At the cutoff of 40, 14, and 47 cells/mL for EpCAM+-CTCs, TSHR+-CTCs, and PDPN+-CTCs, the accuracy of the assay was equivalent to 80.4%, 76.6%, and 77.3%, respectively. On the other hand, the number of EpCAM+-CTCs (p < 0.001), PDPN+-CTCs (p = 0.013), and TSHR+-CTCs (p < 0.001) for patients in the DSM group (n = 17) was significantly higher when compared to the patients who survived (n = 111). At the cutoff of 27, 25, and 9 cells/mL for EpCAM+-CTCs, TSHR+-CTCs, and PDPN+-CTCs, the accuracy of the assay was equivalent to 69.5%, 67.2%, and 68.5%, respectively. These data together indicate that CTC testing is worthy to be considered as a routine clinical test to benefit clinical care of patients with thyroid cancer. Citation Format: Ching-Ping Tseng, Jen-Der Lin, Miaw-Jene Liou, Wei-Shan Hung, Hsueh-Ling Hsu, Kong-Kit Leong, Yu-Ting Chen, Ju-Chien Cheng. Circulating tumor cells as the prognostic marker for non-remission and disease-specific mortality of patients with thyroid cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5586.

Current methods for clinical early detection and disease monitoring of patients with colorectal cancer (CRC) are immunochemical fecal occult blood test (iFOBT) and serum levels of carcinoembryonic antigen (CEA), which are known with low sensitivity. There is an unmet need to seek for additional molecular tools for early detection and disease monitoring of patients with CRC. Whether enumeration of circulating tumor cells (CTCs) supplements current clinical tests and facilitates early detection and monitoring disease progression was investigated. A total of 109 pre-operative patients with CRC (including early and advanced stages) and 65 non-cancerous controls were enrolled in this study. CTCs were enriched from the peripheral blood of these individuals by using the PowerMag negative selection system. Immunofluorescence staining of epithelial cell adhesion molecule (EpCAM), and podoplanin (PDPN, a marker related to poor cancer progression) was performed to define the two distinct subtypes of CTCs. Heterogeneous CTCs expressing PDPN or EpCAM are defined in the peripheral blood of patients with CRC. Regardless clinical stages in patients, the number of both EpCAM+-CTCs and PDPN+-CTCs explicitly differentiated non-cancerous controls and patients with CRC, and were also correlated with clinicopathological diagnosis. Receiver operating characteristic analysis demonstrated that the sensitivity and specificity of EpCAM+-CTCs was 86.32% and 78.46%, respectively, when the cutoff value was 23 EpCAM+-CTCs/mL. Using 7 PDPN+-CTCs/mL as the cutoff value, the sensitivity and specificity of PDPN+-CTCs was 77.98% and 75.38%, respectively. 84.2% and 80.3% of patients with serum CEA < 5 ng/mL were found to have higher EpCAM+-CTCs and PDPN+-CTCs counts, respectively. In addition, simultaneous measurements of iFOBT and CTCs could compromise the false-positive rate of iFOBT, while measurements of CEA and CTCs are applicable to monitor cancer recurrence after surgery. This study implicates that CTC testing supplements the current clinical methods to facilitate early detection and disease monitoring in CRC. Citation Format: Wei-Shan Hung, Wen-Sy Tsai, Tzu-Min Wang, Hsueh-Ling Hsu, Hsuan Liu, Chia-Yu Yang, Ching-Ping Tseng, Ju-Chien Cheng. Combined analysis of circulating tumor cells, fecal occult blood test and serum carcinoembryonic antigen for early detection and monitoring recurrence of patients with colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4583.

Rationale : Hyperhomocysteinemia contributes to vascular dysfunction and risks of cardiovascular diseases. Stromal cell–derived factor (SDF)-1, a chemokine expressed by endothelial cells (ECs), is highly expressed in advanced atherosclerotic lesions. The interplays among homocysteine, chemokines, and shear stress in regulating vascular endothelial function are not clearly understood. Objective : To investigate the mechanisms for modulations of EC SDF-1 expression by homocysteine and shear stress. Methods and Results : Homocysteine stimulation induced dose- and time-dependent SDF-1 expression and phosphorylation of mitogen-activated protein kinases extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38. By using specific inhibitors, small interfering (si)RNA, and dominant negative mutants, we demonstrated that activation of JNK pathway is critical for the homocysteine-induced SDF-1 expression. Transcription factor ELISA and chromatin immunoprecipitation assays showed that homocysteine increased Sp1- and AP-1–DNA binding activities in ECs. Inhibition of Sp1 and AP-1 activations by specific siRNA blocked the homocysteine-induced SDF-1 promoter activity and expression. Preshearing of ECs for 1 to 4 hours at 20 dyn/cm 2 inhibited the homocysteine-induced JNK phosphorylation, Sp1 and AP-1 activation, and SDF-1 expression. The homocysteine-induced SDF-1 expression was suppressed by NO donor. Inhibitor or siRNA for endothelial NO synthase abolished the shear inhibition of SDF-1 expression. Conclusions : Our findings serve to elucidate the molecular mechanisms underlying the homocysteine induction of SDF-1 expression in ECs and the shear stress protection against this induction.

The nonstructural protein 3 (NS3) of hepatitis C virus (HCV) possesses protease, nucleoside triphosphatase, and helicase activities. Although the enzymatic activities have been extensively studied, the ATP- and RNA-binding domains of the NS3 helicase are not well-characterized. In this study, NS3 proteins with point mutations in the conserved helicase motifs were expressed in Escherichia coli , purified, and analyzed for their effects on ATP binding, RNA binding, ATP hydrolysis, and RNA unwinding. UV cross-linking experiments indicate that the lysine residue in the AX 4 GKS motif is directly involved in ATP binding, whereas the NS3(GR1490DT) mutant in which the arginine-rich motif (1486-QRRGRTGR-1493) was changed to QRRDTTGR bound ATP as well as the wild type. The binding activity of HCV NS3 helicase to the viral RNA was drastically reduced with the mutation at Arg1488 (R1488A) and was also affected by the K1236E substitution in the AX 4 GKS motif and the R1490A and GR1490DT mutations in the arginine-rich motif. Previously, Arg1490 was suggested, based on the crystal structure of an NS3-deoxyuridine octamer complex, to directly interact with the γ-phosphate group of ATP. Nevertheless, our functional analysis demonstrated the critical roles of Arg1490 in binding to the viral RNA, ATP hydrolysis, and RNA unwinding, but not in ATP binding.

Summary Background Reelin is a large extracellular glycoprotein that is present in the peripheral blood. That Reelin interacts with the coagulation components and elicits a functional role in hemostasis has not yet been elucidated. Objectives The hemostatic activity of Reelin is investigated and defined in this study. Methods The interplay of Reelin with coagulation components was elucidated by far-Western and liposome/platelet binding assays. In vivo and ex vivo hemostasis-related analyses of Reelin-deficient mice and plasma were also performed. Results Reelin interacted with the liposomes containing phosphatidylserine (PS) or phosphatidylcholine. Instead of interacting with known Reelin receptors (ApoE receptor 2, very low density lipoprotein receptor and integrin β1), Reelin interacted with PS of the activated platelets. The interaction between Reelin and the coagulation factors of thrombin and FXa was also demonstrated with the Kd of 11.7 and 21.2 nm, respectively. Reelin-deficient mice displayed a prolonged bleeding time and an increase in rebleeding rate. Despite the fact that Reelin deficiency had no significant effect on the clotting time of prothrombin and activated partial thromboplastin time, the fibrin clot formation was abnormal and the fibrin clot structure was relatively loosened with reduced clot strength. Abnormal fibrinogen expression did not account for the hemostatic defects associated with Reelin deficiency. Instead, thrombin generation was impaired concomitant with an altered prothrombin cleavage pattern. Conclusions By interacting with platelet phospholipids and the coagulation factors, thrombin and FXa, Reelin plays a selective role in coagulation activation, leading to thrombin generation and formation of a normal fibrin clot.

Papillary thyroid carcinoma (PTC) is one type of thyroid cancer and accounts for about 80% of the cases. Routine surveillance by serum thyroglobulin (Tg) and medical imaging is the current practice to monitor disease progression of the patients. However, the presence of anti-Tg antibody or other influence factors may discount the value of serum Tg in disease monitoring. Whether enumeration of circulating epithelial cells (CECs) and its combined analyses with serum Tg help to define disease status of PTC patients was investigated. CECs were first enriched from the peripheral blood of the healthy control subjects (G1, n = 17) and the patients at disease-free status (G2, n = 26) or with distant metastasis (G3, n = 22). The number of CECs expressing epithelial cell adhesion molecule (EpCAM) was determined by immunofluorescence microscopy analyses. The medium number of EpCAM+-CECs was 6 (intequartile range 1-11), 12 (interquartile range 7-16) and 91 (interquartile range 31-206) cells/ml of blood for G1, G2 and G3, respectively. EpCAM+-CEC counts were significantly higher in G3 than in G1 (p Citation Format: Ching-Ping Tseng, Jen-Der Lin, Hung-Chih Lin, Ju-Chien Cheng. Combined analysis of circulating epithelial cell count and serum thyroglobulin for differentiating disease status of the patients with papillary thyroid carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 461.

Reelin is an extracellular glycoprotein that is highly conserved in mammals. In addition to its expression in the nervous system, Reelin is present in erythroid cells but its function there is unknown. We report in this study that Reelin is up-regulated during erythroid differentiation of human erythroleukemic K562 cells and is expressed in the erythroid progenitors of murine bone marrow. Reelin deficiency promotes erythroid differentiation of K562 cells and augments erythroid production in murine bone marrow. In accordance with these findings, Reelin deficiency attenuates AKT phosphorylation of the Ter119+CD71+ erythroid progenitors and alters the cell number and frequency of the progenitors at different erythroid differentiation stages. A regulatory role of Reelin in erythroid differentiation is thus defined.

We investigated the effect of traditional risk factors (hypertension, dyslipidemia and smoking) on the association between angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and peripheral arterial disease (PAD) in 945 (454 men and 491 women) Taiwanese type 2 diabetic patients with a mean age of 63.5 (SD: 11.4) years. Among them, 81 (31 men and 50 women) had PAD (ankle-brachial index

Background Many studies concentrate on variation in the hemagglutinin glycoprotein (HA) because of its significance in host immune response, the evolution of this virus is even more complex when other genome segments are considered. Recently, it was found that cytotoxic T lymphocytes (CTL) play an important role in immunity against influenza and most CTL epitopes of human influenza viruses were remarkably conserved. The NP gene has evolved independently in human and avian hosts after 1918 flu pandemic and it has been assigned a putative role as a determinant of host range. Methods and Findings Phylodynamic patterns of the genes encoding nucleoprotein (NP) of influenza A viruses isolated from 1979–2009 were analyzed by applying the Bayesian Markov Chain Monte Carlo framework to better understand the evolutionary mechanisms of these Taiwanese isolates. Phylogenetic analysis of the NP gene showed that all available H3 worldwide isolates collected so far were genetically similar and divided into two major clades after the year 2004. We compared the deduced amino acid sequences of the NP sequences from human, avian and swine hosts to investigate the emergence of potential adaptive mutations. Overall, selective pressure on the NP gene of human influenza A viruses appeared to be dominated by purifying selection with a mean dN/dS ratio of 0.105. Site-selection analysis of 488 codons, however, also revealed 3 positively selected sites in addition to 139 negatively selected ones. Conclusions The demographic history inferred by Bayesian skyline plot showed that the effective number of infections underwent a period of smooth and steady growth from 1998 to 2001, followed by a more recent rise in the rate of spread. Further understanding the correlates of interspecies transmission of influenza A virus genes from other host reservoirs to the human population may help to elucidate the mechanisms of variability among influenza A virus.

The Chinese herb modified Yi Guan Jian (mYGJ) is an effective regimen that is usually used in outpatients with chronic liver diseases such as fibrosis and cirrhosis. However, the mechanism for the action of mYGJ on liver fibrosis is not yet clear. In this study, we found that mYGJ induced hepatic stellate cells (HSCs) apoptosis concomitant with the downregulation of Bcl-2 expression and slight elevation of Bax level. Moreover, the reactive oxygen species (ROS) were generated in the early stages of mYGJ-induced HSCs apoptosis to facilitate calcium and cytochrome c release from the mitochondria to cytosol. Subsequently, caspase 9 and caspase 3 were activated. Furthermore, the activation of ER stress-associated caspase 12 in HSCs was also evaluated. Together, we report the first evidence-based study to demonstrate that mYGJ decoction induces HSCs apoptosis through ROS accumulation and the intrinsic apoptosis pathway. These findings provide rationale for further clinical investigation of traditional Chinese medicine recipes against liver fibrosis.

Background Bacterial DNA contamination in PCR reagents has been a long standing problem that hampers the adoption of broad-range PCR in clinical and applied microbiology, particularly in detection of low abundance bacteria. Although several DNA decontamination protocols have been reported, they all suffer from compromised PCR efficiency or detection limits. To date, no satisfactory solution has been found. Methodology/Principal Findings We herein describe a method that solves this long standing problem by employing a broad-range primer extension-PCR (PE-PCR) strategy that obviates the need for DNA decontamination. In this method, we first devise a fusion probe having a 3′-end complementary to the template bacterial sequence and a 5′-end non-bacterial tag sequence. We then hybridize the probes to template DNA, carry out primer extension and remove the excess probes using an optimized enzyme mix of Klenow DNA polymerase and exonuclease I. This strategy allows the templates to be distinguished from the PCR reagent contaminants and selectively amplified by PCR. To prove the concept, we spiked the PCR reagents with Staphylococcus aureus genomic DNA and applied PE-PCR to amplify template bacterial DNA. The spiking DNA neither interfered with template DNA amplification nor caused false positive of the reaction. Broad-range PE-PCR amplification of the 16S rRNA gene was also validated and minute quantities of template DNA (10–100 fg) were detectable without false positives. When adapting to real-time and high-resolution melting (HRM) analytical platforms, the unique melting profiles for the PE-PCR product can be used as the molecular fingerprints to further identify individual bacterial species. Conclusions/Significance Broad-range PE-PCR is simple, efficient, and completely obviates the need to decontaminate PCR reagents. When coupling with real-time and HRM analyses, it offers a new avenue for bacterial species identification with a limited source of bacterial DNA, making it suitable for use in clinical and applied microbiology laboratories.

Abnormalities of platelet functions have been linked to reelin-impaired neuronal disorders. However, little attention has been given to understanding the interplay between reelin and platelet. In this study, reelin was found to present in the human platelets and megakaryocyte-like leukemic cells. Reelin-binding assays revealed that extracellular reelin can interact with platelets through the receptor belonging to the low density lipoprotein receptor gene family. The reelin-to-platelet interactions enhance platelet spreading on fibrinogen concomitant with the augmentation of lamellipodia formation and F-actin bundling. In contrast, reelin has no effect on integrin alphaIIbbeta3 activation and agonist-induced platelet aggregation. Molecular analysis revealed that the up-regulation of Rac1 activity and the inhibition of protein kinase C delta-Thr505 phosphorylation are important for reelin-mediated enhancement of platelet spreading on fibrinogen. These findings demonstrate for the first time that reelin is present in platelets and the reelin-to-platelet interactions play a novel role in platelet signaling and functions.

Chronic hepatitis C virus (HCV) infection is a worldwide public issue. In this study, we performed bioactivity-guided screening of the Lonicera hypoglauca Miq. crude extracts to find for naturally chemical entities with anti-HCV activity. Pheophytin a was identified from the ethanol-soluble fraction of L. hypoglauca that elicited dose-dependent inhibition of HCV viral proteins and RNA expression in both replicon cells and cell culture infectious system. Computational modeling revealed that pheophytin a can bind to the active site of HCV-NS3, suggesting that NS3 is a potent molecular target of pheophytin a. Biochemical analysis further revealed that pheophytin a inhibited NS3 serine protease activity with IC(50)=0.89 microM. Notably, pheophytin a and IFNalpha-2a elicited synergistic anti-HCV activity in replicon cells with no significant cytotoxicity. This study thereby demonstrates for the first time that pheophytin a is a potent HCV-NS3 protease inhibitor and offers insight for development of novel anti-HCV regimens.

Background The effect of traditional risk factors on the association between angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and stroke was rarely studied previously. We investigated such effect in Taiwanese type 2 diabetic patients. Materials and methods A total of 872 (422 men and 450 women) patients aged 63·5 (SD: 11·6) years were recruited. Among them, 92 cases (48 men and 44 women) had stroke. Polymerase chain reaction was used to classify the genotypes as II, ID and DD. Analyses were performed in separate sexes. Results The adjusted odds ratios for stroke for ID vs. II and DD vs. II were 0·837 (0·413–1·697) and 1·778 (0·596–5·300), respectively, for men; but were 1·700 (0·824–3·505) and 3·706 (1·375–9·985), respectively, for women. In models assuming recessive (DD vs. II + ID), dominant (DD + ID vs. II) and additive (II = 0, ID = 1 and DD = 2) transmission, none of the odds ratios was significant for men; but were all significant for women: 2·784 (1·137–6·818), 1·996 (1·006–3·962) and 1·877 (1·155–3·050), respectively. In models using patients without risk factors (hypertension, obesity, smoking or dyslipidaemia ) as a referent group and comparing them to patients with the risk factor and with ID/II, and with DD genotypes, all models (except for smoking) favoured an increasing trend of risk with patients having the risk factor and DD genotype at the highest risk in women. Similar trends for hypertension and dyslipidaemia were also observed in men. Conclusion Traditional risk factors play an important role in the association between the ACE genotypes and stroke. Patients with DD genotype and having traditional risk factors are at the highest risk.

Disabled-2 (DAB2) is an adapter protein that plays a key role in cell proliferation and differentiation. We reported here that DAB2 is expressed in various regions of rat central nervous system and is most abundant in the olfactory bulb. The up-regulation of DAB2 upon 5,7-dihydroxytryptamine-induced spinal cord lesion implicates that DAB2 may participate in the regulation of neuronal plasticity. To investigate DAB2 function in the regulation of neurite outgrowth, the rat p59 and p82 form of DAB2 was individually and stably expressed in the PC12 cells. Both p59 and p82 inhibited nerve growth factor (NGF)-induced neurite outgrowth concomitantly with a decrease in the expression of neuron-specific cytoskeleton protein β-tubulin III. To unveil the molecular mechanism of DAB2 in NGF signaling, we found that RhoA-GTPase activity was up-regulated in DAB2 stable lines whereas the Ras/MAPK and PI3-kinase/Akt signaling was not affected. The inhibitory effect of DAB2 on NGF-mediated neurite outgrowth was reversed by the pretreatment of Rho-kinase (ROCK) inhibitor Y27632, implicating that DAB2 modulates RhoA/ROCK signaling. Together, this study defines a role of DAB2 in the control of neuronal plasticity and demonstrates for the first time that DAB2 is a negative regulator in NGF-mediated neurite outgrowth.

Platelet aggregation plays a pivotal role in the haemostatic process and is involved in the pathological counterpart of arterial thrombosis. We have shown that the adapter protein disabled-2 (DAB2) is expressed abundantly in platelets. In this study, DAB2 was found to distribute in the platelet alpha-granules and was released from the granular compartment upon platelet activation. The secreted DAB2 binds to the extracellular region of alphaIIbbeta3 integrin on the platelet surface through the phosphotyrosine-binding domain. The DAB2-platelet interactions result in the inhibition of agonist-induced platelet aggregation with the exception of thrombin, a DAB2 protease that renders DAB2 inactive. Biochemical and mutational analysis revealed that the DAB2 cell-adhesion Arg-Gly-Asp (RGD) motif (amino acid residues 64-66) and the alphaIIb-integrin-fibrinogen-binding region (amino acid residues 171-464) are important for the DAB2-platelet interactions. Such interactions compete for the binding of alphaIIb integrin with fibrinogen and provide a mechanism for DAB2 to inhibit platelet aggregation. Accordingly, the synthetic RGD-motif-containing DAB2 peptide PDARGDKM also elicited anti-platelet aggregation activity. These findings demonstrate for the first time that DAB2 is an alphaIIb-integrin-binding protein that plays a novel role in the control of platelet-fibrinogen interactions and platelet aggregation.

Disabled-2 (DAB2) is an adapter protein that is up-reg-ulated during megakaryocytic differentiation of hematopoietic cells and is abundantly expressed in platelets. In this study, the role of DAB2 in integrin alpha(IIb)beta(3)-mediated matrix protein fibrinogen adhesion and cell signaling was investigated. In K562 cells differentiating to the megakaryocytic lineage, down-regulation of DAB2 by DAB2 small interfering RNA augmented integrin alpha(IIb)beta(3) activation and resulted in an increase in cell adhesion to fibrinogen. Ectopic expression of DAB2 reversed the DAB2 small interfering RNA effect or, by itself, decreased fibrinogen adhesion of K562 cells. Mutational analysis revealed that a DAB2 Ser(24) phosphorylation mutant (S24A) abrogated the inhibitory function of DAB2. The spatial and temporal association/interaction of DAB2 and platelet integrin alpha(IIb)beta(3) (CD61) in both megakaryocytic cells and platelets led us to examine the effect of Ser(24) phosphorylation on the interaction between DAB2 and integrin beta(3). Through cellular localization and co-immunoprecipitation analysis, we demonstrate for the first time that Ser(24) phosphorylation promotes membrane translocation of DAB2 and its subsequent interaction with integrin beta(3), thereby defining a mechanism for DAB2 in regulating integrin alpha(IIb)beta(3) activation and inside-out signaling. Consistent with the effect on fibrinogen adhesion, Ser(24) phosphorylation of DAB2 was also involved in the negative regulation of alpha(IIb)beta(3)-induced T cell factor transcriptional activity. In contrast, the S24A mutant acted like wild-type DAB2 and inhibited both beta-catenin- and plakoglobin-mediated T cell factor transactivation. Hence, DAB2 elicits distinct regulatory mechanisms in alpha(IIb)beta(3) and beta-catenin/plakoglobin signaling in a Ser(24) phosphorylation-dependent and -independent manner, respectively. These findings indicate Ser(24) phosphorylation as a molecular basis for DAB2 acting as a negative regulator in alpha(IIb)beta(3) inside-out signaling and contribute to our understanding of DAB2 in megakaryocytic differentiation and platelet function.

Distant metastasis of papillary thyroid cancer (PTC) is a multistep and complex process that frequently complicates the disease with poor prognosis. The presence of circulating tumor cells (CTCs) in the peripheral blood has been reported in several cancer types to be highly related to the development of distant metastasis. Nevertheless, the CTCs status during the progression of PTC is rarely investigated. This study aimed to define and compare the CTCs counts among the healthy control individuals (Group I, n = 14), the PTC patients in disease-free status (Group II, n = 9), and the patients with distant metastasis (Group III, n = 8). The patients in group III had metastases to the lung and mediastinum (n = 4), bones (n = 3), and lung and kidney (n = 1), respectively. CTCs were enriched from the peripheral blood by the negative selection method PowerMag that has been validated in our previous study. CTCs enumeration was performed by immunofluorescence staining using the anti-epithelial cell adhesion molecule (EpCAM) and anti-thyroid stimulating hormone receptor (TSHR) antibodies. The EpCAM+ and TSHR+ CTCs counts were 2.97 ± 2.03 and 9.97 ± 9.22 cells/mL for group I, 10.43 ± 9.03 and 19.17 ± 9.77 cells/mL for group II, and 100.06 ± 73.34 and 141.60 ± 82.08 cells/mL for group III individuals, respectively (p < 0.01). These data indicate that (1) some of the TSHR+-CTCs are not EpCAM+ and this type of cell population can be overlooked if CTCs were enriched by the method based on positive selection of EpCAM+ cells; (2) the PTC patients in disease-free status has higher CTCs counts than the healthy control individuals and, hence, continuous CTCs enumeration is recommended for the patient in the stage of disease-free; (3) the PTC patients with distant metastases have higher CTCs counts when compares to the healthy control subjects and the patients with disease-free status. In conclusion, CTCs enumeration is thereby warranted in the course of diagnosis and treatment of thyroid cancer. Citation Format: Hung-Chih Lin, Ju-Chien Cheng, Ching-Ping Tseng, Jen-Der Lin. Distinct levels of circulating tumor cell counts for the papillary thyroid cancer patients with distant metastases and in disease-free status. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2097. doi:10.1158/1538-7445.AM2014-2097

The number of circulating tumor cells (CTCs) has been demonstrated as a good indicator for cancer progression and for monitoring treatment response of cancer patients. Most of the current methods for detecting CTCs were based on positive selection using the antibody specific to epithelial cell surface marker. In this study, we established a novel PowerMag system for negative selection and enrichment of CTCs by depletion of CD45+ cells. The efficacy of PowerMag system in CTCs isolation was first analyzed by spiking prostatic PC3 cancer cells into the peripheral blood from healthy volunteers. Our data revealed that, when compared with the methods that have been reported, the PowerMag system had high sensitivity (6-7 log10 enrichment), comparable recovery rate (50-60%), broad detection range (more than 3 log10), and stable and reproducible experimental results (r2=0.999). Notably, the cancer cells obtained from PowerMag system were label-free and viable with the capability for proliferation. To validate the feasibility of PowerMag system in clinical application, the numbers and characteristics of CTCs from 38 metastatic cancer patients with a total of 175 blood samples were determined. At least two populations of CTCs with the surface markers of EpCAM+CD45−CD146− and EpCAM−CD45−CD146− were identified. The detection rate reached 100% for the patients in the baseline level before treatment. The change in CTCs numbers for both cell populations appears to correlate with patient clinical outcomes after chemotherapy. As a whole, the PowerMag system is proven to be capable of isolating CTCs from whole blood effectively and economically, by which time- consuming sample pretreatment and costly equipments are not required. PowerMag has paved an alternation rout to monitor the progression and treatment response of cancer patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2383. doi:1538-7445.AM2012-2383

Tumor necrosis factor receptor-associated factor 6 (TRAF6) is an ubiquitin E3 ligase that catalyzes lysine-63 linked polyubiquitination of various signaling proteins. The recruitment and formation of different protein complexes with TRAF6 leads to activation of TRAF6-associated signaling and regulates cell proliferation and apoptosis. In this study, we search for novel TRAF6-binding partners that may have implication in TRAF6 signaling and cancer progression. Bioinformatic analysis identified a putative TRAF6-binding protein (TRAF6BP) that contains the consensus TRAF6-binding motif X-X-P-X-E-X-X-Ar/Ac-X and thereby TRAF6BP was subjected to further characterization. In accord with the bioinformatics prediction, coimmunoprecipitation analysis demonstrated the binding between TRAF6BP and TRAF6. TRAF6BP also interacts with other TRAF proteins including TRAF-2, −3, −5 but the interaction was much weaker than TRAF6. Domain mapping with TRAF6 deletion mutants identified the TRAF-C domain of TRAF6 is important for its interaction with TRAF6BP. In vivo ubiquitination assay further unveiled that TRAF6BP is a substrate of TRAF6 E3 ligase and underwent ubiquitination in the presence of TRAF6. Only the expression of full-length TRAF6, but not the TRAF-C deletion mutants of TRAF6 resulted in the ubiquitination of TRAF6BP. In addition, TRAF6BP ubiquitiation was abrogated when the lysine-63 ubiquitin mutant (K63R) but not the lysine-48 mutant (K48R) was used as the ubiquitin substrate. Together, we demonstrated for the first time that TRAF6BP is a novel TRAF6-binding protein and is a potential lysine-63 ubiquitination substrate of TRAF6; the TRAF6BP-TRAF6 interaction is essential for TRAF6 to ubiquitinate TRAF6BP. The significances of TRAF6BP-TRAF6 interactions and TRAF6BP ubiquitination in cancer progression and TRAF6 signaling are worthy to further investigation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1268.

Previous studies have shown that Disabled-2 (DAB2) is up-regulated during megakaryocytic differentiation of human K562 cells. To delineate the consequences of DAB2 induction, a DNA vector-based small interfering RNA (siRNA) was designed to intervene in DAB2 expression. We found that DAB2 siRNA specifically inhibited DAB2 induction, resulting in the modulation of cell–cell adhesion and mitogen-activated protein kinase (MAPK) phosphorylation. The morphological changes and β3 integrin expression associated with megakaryocytic differentiation were not affected. Since the MAPK pathway has been shown to involve DAB2 induction [Tseng et al., Biochem. Biophys. Res. Commun. 285 (2001) 129–135], our results suggest a reciprocal regulation between DAB2 and MAPK in the differentiation of K562 cells. In addition, we have demonstrated for the first time that DAB2 siRNA is a valuable tool for unveiling the biological consequences of DAB2 expression.

Platelet-derived growth factor (PDGF) is involved in megakaryocytopoiesis and is secreted into the culture medium during megakaryocytic differentiation of human leukemic cells. We investigate whether PDGF plays a role in the regulation of the adapter protein Disabled-2 (DAB2) that expresses abundantly in platelets and megakaryocytes. Western blot analysis revealed that conditioned medium from 12-O-tetradecanoylphorbol-13-acetate (TPA)-treated, megakaryocytic differentiating K562 cells upregulated DAB2 expression. DAB2 induction and megakaryocytic differentiation was abrogated when cells were co-treated with the PDGF receptor inhibitor STI571 or when the conditioned medium was derived from TPA-plus STI571-treated cells. Although the level of PDGF mRNA was not altered by STI571, an approximate 44% decrease in PDGF in the conditioned medium was observed. Consistent with these findings, interfering PDGF signaling by PDGF neutralization antibody or dominant negative PDGF receptors attenuated DAB2 expression. Accordingly, transfection of an expression plasmid encoding secreted PDGF upregulated DAB2. This study shows for the first time that PDGF autocrine signaling regulates DAB2 expression during megakaryocytic differentiation.

Endocytosis is pivotal for uptake of fibrinogen from plasma into megakaryocytes and platelet α-granules. Due to the complex adaptor and cargo contents in endocytic vehicles, the underlying mechanism of fibrinogen uptake is not yet completely elucidated. In this study, we investigated whether the endocytic adaptor protein Disabled-2 (DAB2) mediates fibrinogen uptake in an adaptor-specific manner. By employing primary megakaryocytes and megakaryocytic differentiating human leukemic K562 cells as the study models, we found that fibrinogen uptake is associated with the expression of integrin αIIbβ3 and DAB2 and is mediated through clathrin-dependent manner. Accordingly, constitutive and inducible knockdown of DAB2 by small interfering RNA reduced fibrinogen uptake for 53.2 ± 9.8% and 59.0 ± 10.7%, respectively. Culturing the cells in hypertonic solution or in the presence of clathrin inhibitor chlorpromazine abrogated clathrin-dependent endocytosis and diminished the uptake of fibrinogen. Consistent with these findings, 72.2 ± 0.2% of cellular DAB2 was colocalized with clathrin, whereas 56.4±4.1% and 54.6 ± 2.0% of the internalized fibrinogen were colocalized with clathrin and DAB2, respectively. To delineate whether DAB2 mediates fibrinogen uptake in an adaptor-specific manner, K562 stable cell lines with knockdown of the adaptor protein-2 (AP-2) or double knockdown of AP-2/DAB2 were established. The AP-2 knockdown cells elicited normal fibrinogen uptake activity but the uptake of collagen was diminished. In addition, collagen uptake was further reduced in DAB2/AP-2 knockdown cells. These findings thereby define an adaptor-specific mechanism in the control of fibrinogen uptake and implicate that DAB2 is the key adaptor in the clathrin-associated endocytic complexes to mediate fibrinogen internalization.