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1.  Hypoxia potentiates Notch signaling in breast cancer leading to decreased E-cadherin expression and increased cell migration and invasion 
British Journal of Cancer  2009;102(2):351-360.
Epithelial-to-mesenchymal transition (EMT) is associated with decreased adhesion and acquisition of metastatic potential of breast cancer cells. Epithelial-to-mesenchymal transition is mediated, in part, by two transcription repressors, Snail and Slug, that are known to be targets of the Notch signaling pathway, and JAGGED1-induced Notch activation increases EMT. However, the events that lead to increased Notch activity during EMT of breast cancer cells are unknown.
The accumulation of hypoxia inducible factors (HIFs) under hypoxia was detected by western blot analysis, and their effects on Notch signaling were measured by an in vitro Notch reporter assay. The expression of Notch target genes under hypoxia was tested by real-time PCR. The knockdown of HIF-1α was mediated by retroviral delivery of shRNA. The expression of Slug and Snail under hypoxia was measured by real-time PCR. Breast cancer cell migration and invasion under hypoxia were tested with cell migration and invasion kits.
Hypoxia increased the expression of Notch target genes such as HES1 and HEY1 in breast cancer cells, as was expression of Notch receptors and ligands. The mechanism is likely to involve the accumulation of HIF-1α and HIF-2α in these cells by hypoxia, which synergised with the Notch co-activator MAML1 in potentiating Notch activity. Hypoxia inducible factor-1α was found to bind to HES1 promoter under hypoxia. Knockdown of HIF-1α with shRNA inhibited both HES1 and HEY1 expression under hypoxia. Hypoxia increased the expression of Slug and Snail, and decreased the expression of E-cadherin, hallmarks of EMT. Notch pathway inhibition abrogated the hypoxia-mediated increase in Slug and Snail expression, as well as decreased breast cancer cell migration and invasion.
Hypoxia-mediated Notch signaling may have an important role in the initiation of EMT and subsequent potential for breast cancer metastasis.
PMCID: PMC2816657  PMID: 20010940
Notch; hypoxia; hypoxia inducible factor (HIF); breast cancer; epithelial-to-mesenchymal transition (EMT)
3.  Whole-Genome Sequence of “Candidatus Liberibacter asiaticus” from Guangdong, China 
Genome Announcements  2014;2(2):e00273-14.
The draft genome sequence of “Candidatus Liberibacter asiaticus” strain A4, isolated from a mandarin citrus in Guangdong, People’s Republic of China, is reported. The A4 strain has a genome size of 1,208,625 bp, G+C content of 36.4%, 1,107 predicted open reading frames, and 53 RNA genes.
PMCID: PMC3983304  PMID: 24723715
4.  Draft Genome Sequence of Xylella fastidiosa Pear Leaf Scorch Strain in Taiwan 
Genome Announcements  2014;2(2):e00166-14.
The draft genome sequence of Xylella fastidiosa pear leaf scorch strain PLS229, isolated from the pear cultivar Hengshan (Pyrus pyrifolia) in Taiwan, is reported here. The bacterium has a genome size of 2,733,013 bp, with a G+C content of 53.1%. The PLS229 genome was annotated and has 3,259 open reading frames and 50 RNA genes.
PMCID: PMC3961722  PMID: 24652975
5.  ING1b-inducible microRNA203 inhibits cell proliferation 
British Journal of Cancer  2013;108(5):1143-1148.
The ING family of type II tumour suppressors serve as both epigenetic ‘readers' and target histone acetyl transferase (HAT) and histone deacetylase (HDAC) ‘writers' of the epigenetic histone code. The ING1 protein has also been implicated in regulating microRNA (miRNA) levels. In this study, we identify a link between ING1b and the miRNA epigenetic network.
Primary fibroblasts infected with adenoviruses expressing GFP control or GFP plus ING1b were examined for alterations in miRNA profiles using a miRNA PCR array. Additional experiments confirmed specificity and consequences of altered miRNA expression.
MicroRNAs miR-203, miR-375, miR-449b and miR-200c were increased by ING1b overexpression. Ectopic expression of miR-203 inhibited U2OS and MDA-MB-231 cancer cell growth, and induced G1 cell cycle arrest in U2OS cells as estimated by flow cytometry. Transfection with miR-203 inhibitor reversed the proliferation inhibition induced by ING1b in U2OS cells. CHIP assays showed that ING1b bound to the promoter of miR-203. Western blot analyses showed that CDK6, c-Abl and Src were downregulated by the transfection of miR-203.
These results indicate that ING1b epigenetically regulates several miRNAs including miR-203. The several-fold increase in miR-203 by ING1b might inhibit cancer cell proliferation through coordinate downregulation of CDK6, c-Abl and Src.
PMCID: PMC3619068  PMID: 23462723
ING1; transcriptional regulation; mir-203; CDK6; c-Abl; Src
6.  Botulinum toxin injections combined with or without sodium hyaluronate in the absence of electromyography for the treatment of infantile esotropia: a pilot study 
Chen, J | Deng, D | Zhong, H | Lin, X | Kang, Y | Wu, H | Yan, J | Mai, G
Eye  2012;27(3):382-386.
To evaluate the feasibility and safety of a revised technique of botulinum toxin type A (BTA) injections for the treatment of infantile esotropia.
Forty-seven patients with infantile esotropia were randomly divided into two groups. In group A, 23 cases were treated with a bilateral injection of 2.5–3.75 U BTA combined with sodium hyaluronate (SH) to the medial rectus muscle. In group B, 24 cases were treated with a bilateral injection of 2.5–3.75 U BTA solution alone to the medial rectus muscle. Electromyography was not used in the study. All patients received one injection and were evaluated 2 weeks, 3 months, and 6 months following injection.
The measured changes between groups A and B included the frequencies of good alignment 6 months after injections (30.4% vs 37.5%), complicated ptosis (2.2% vs 20.8%), and vertical deviation (2.2% vs 2.1%).
BTA injections combined with or without SH in the absence of electromyography demonstrated effectiveness and feasibility in the treatment of infantile esotropia. A relative decrease in the frequency of complicated ptosis resulted from injections of BTA+SH.
PMCID: PMC3597871  PMID: 23238444
botulinum toxin; infantile esotropia; sodium hyaluronate; complication
7.  Longikaurin A, a natural ent-kaurane, induces G2/M phase arrest via downregulation of Skp2 and apoptosis induction through ROS/JNK/c-Jun pathway in hepatocellular carcinoma cells 
Cell Death & Disease  2014;5(3):e1137-.
Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer, and is also highly resistant to conventional chemotherapy treatments. In this study, we report that Longikaurin A (LK-A), an ent-kaurane diterpenoid isolated from the plant Isodon ternifolius, induced cell cycle arrest and apoptosis in human HCC cell lines. LK-A also suppressed tumor growth in SMMC-7721 xenograft models, without inducing any notable major organ-related toxicity. LK-A treatment led to reduced expression of the proto-oncogene S phase kinase-associated protein 2 (Skp2) in SMMC-7721 cells. Lower Skp2 levels correlated with increased expression of p21 and p-cdc2 (Try15), and a corresponding decrease in protein levels of Cyclin B1 and cdc2. Overexpression of Skp2 significantly inhibited LK-A-induced cell cycle arrest in SMMC-7721 cells, suggesting that LK-A may target Skp2 to arrest cells at the G2/M phase. LK-A also induced reactive oxygen species (ROS) production and apoptosis in SMMC-7721 cells. LK-A induced phosphorylation of c-Jun N-terminal kinase (JNK), but not extracellular signal-regulated kinase and P38 MAP kinase. Treatment with, the JNK inhibitor SP600125 prevented LK-A-induced apoptosis in SMMC-7721 cells. Moreover, the antioxidant N-acetylcysteine prevented phosphorylation of both JNK and c-Jun. Taken together, these data indicate that LK-A induces cell cycle arrest and apoptosis in cancer cells by dampening Skp2 expression, and thereby activating the ROS/JNK/c-Jun signaling pathways. LK-A is therefore a potential lead compound for development of antitumor drugs targeting HCC.
PMCID: PMC3973226  PMID: 24651440
Longikaurin A; hepatocellular carcinoma; cell cycle arrest; apoptosis; Skp2
8.  Large Eddy Simulation of Powered Fontan Hemodynamics 
Journal of biomechanics  2012;46(2):408-422.
Children born with univentricular heart disease typically must undergo three open heart surgeries within the first 2–3 years of life to eventually establish the Fontan circulation. In that case the single working ventricle pumps oxygenated blood to the body and blood returns to the lungs flowing passively through the Total Cavopulmonary Connection (TCPC) rather than being actively pumped by a subpulmonary ventricle. The TCPC is a direct surgical connection between the superior and inferior vena cava and the left and right pulmonary arteries. We have postulated that a mechanical pump inserted into this circulation providing a 3–5 mmHg pressure augmentation will reestablish bi-ventricular physiology serving as a bridge-to-recovery, bridge-to-transplant or destination therapy as a “biventricular Fontan” circulation. The Viscous Impeller Pump (VIP) has been proposed by our group as such an assist device. It is situated in the center of the 4-way TCPC intersection and spins pulling blood from the vena cavae and pushing it into the pulmonary arteries. We hypothesized that Large Eddy Simulation (LES) using high-order numerical methods are needed to capture unsteady powered and unpowered Fontan hemodynamics. Inclusion of a mechanical pump into the CFD further complicates matters due to the need to account for rotating machinery. In this study, we focus on predictions from an in-house high-order LES code (WenoHemo™) for unpowered and VIP-powered idealized TCPC hemodynamics with quantitative comparisons to Stereoscopic Particle Imaging Velocimetry (SPIV) measurements. Results are presented for both instantaneous flow structures and statistical data. Simulations show good qualitative and quantitative agreement with measured data.
PMCID: PMC3552034  PMID: 23177085
High Order Large Eddy Simulation; Fontan circulation; Viscous Impeller Pump
9.  Planar cell polarity effector gene Intu regulates cell fate-specific differentiation of keratinocytes through the primary cilia 
Cell Death and Differentiation  2012;20(1):130-138.
Genes involved in the planar cell polarity (PCP) signaling pathway are essential for a number of developmental processes in mammals, such as convergent extension and ciliogenesis. Tissue-specific PCP effector genes of the PCP signaling pathway are believed to mediate PCP signals in a tissue- and cell type-specific manner. However, how PCP signaling controls the morphogenesis of mammalian tissues remains unclear. In this study, we investigated the role of inturned (Intu), a tissue-specific PCP effector gene, during hair follicle formation in mice. Tissue-specific disruption of Intu in embryonic epidermis resulted in hair follicle morphogenesis arrest because of the failure of follicular keratinocyte to differentiate. Targeting Intu in the epidermis resulted in almost complete loss of primary cilia in epidermal and follicular keratinocytes, and a suppressed hedgehog signaling pathway. Surprisingly, the epidermal stratification and differentiation programs and barrier function were not affected. These results demonstrate that tissue-specific PCP effector genes of the PCP signaling pathway control the differentiation of keratinocytes through the primary cilia in a cell fate- and context-dependent manner, which may be critical in orchestrating the propagation and interpretation of polarity signals established by the core PCP components.
PMCID: PMC3524640  PMID: 22935613
Planar cell polarity; Intu; cilia; keratinocyte; epidermis; hair follicle
10.  Performance evaluation of a pediatric viscous impeller pump for Fontan cavopulmonary assist 
The anatomic and physiologic constraints for pediatric cavopulmonary assist differ markedly from adult Fontan circulations due to smaller vessel sizes and risk of elevated pulmonary resistance. In this study, hemodynamic and hemolysis performance capability of a catheter-based viscous impeller pump (VIP) to power the Fontan circulation is assessed at a pediatric scale (~15 kg) and performance range (0-30 mmHg).
Computer simulation and mock circulation studies were conducted to assess the hydraulic performance, acute hemodynamic response to different levels VIP support, and the potential for vena cavae collapse. Computational fluid dynamics (CFD) simulations were used to estimate VIP hydraulic performance, shear rates, and potential for hemolysis. Hemolysis was quantified in a mock loop with fresh bovine blood.
A VIP augmented 4-way total cavopulmonary connection flow at pediatric scales and restored systemic pressures and flows to biventricular values, without causing flow obstruction or suction. VIP generated flows up to 4.1 L/min and pressure heads of up to 38 mmHg at 11,000 rpm. Maximal shear rate was 160 Pa, predicting low hemolysis risk. Observed hemolysis was low with plasma free hemoglobin of 11.4 mg/dL/hr.
A VIP will augment Fontan cavopulmonary flow in the proper pressure and flow ranges, with low hemolysis risk under more stringent pediatric scale and physiology compared to adult scale. This technology may be developed to simultaneously reduce systemic venous pressure and improve cardiac output after stage-2 or -3 Fontan repair. It may serve to compress surgical staging, lessening the pathophysiologic burden of repair.
PMCID: PMC3525746  PMID: 22421403
Fontan Circulation; cavopulmonary assist device; mock circulation; CFD; pump performance; hemolysis
Neuroscience  2012;227:223-231.
Human umbilical cord blood cells (HUCBCs) have been employed as a restorative treatment for experimental stroke. In this study, we investigated whether transplantation of sub-therapeutic doses of HUCBCs and Simvastatin enhances cerebral vascular remodeling after stroke. Adult male Wistar rats (n=34) were subjected to transient middle cerebral artery occlusion (MCAo) and treated with: phosphate buffered solution (PBS, gavaged daily for 7 days); Simvastatin (0.5mg/kg, gavaged daily for 7 days); HUCBCs (1x106, injected once via tail vein); and combination Simvasatin with HUCBCs, starting at 24 h after MCAo. There was no significant difference between Simvastatin- or HUCBC-monotherapy and MCAo-alone group. Combination treatment 24 h post-stroke significantly increased the perimeter of von Willebrand factor (vWF)-positive vessels, the diameter and density of alpha smooth muscle actin ( SMA)-positive arteries, and the percentage of BrdU-positive endothelial cells (ECs) in the ischemic boundary zone (IBZ) compared with MCAo-alone or HUCBC-monotherapy 14 days after MCAo (p<0.05, n=8/group); Combination treatment significantly increased the densities of vWF-vessels and SMA-arteries as well as the densities of BrdU-ECs and BrdU-positive smooth muscle cells (SMCs) in vascular walls in the IBZ compared with Simvastatin-monotherapy. Moreover, the increased BrdU-ECs and BrdU-SMCs were significantly correlated with neurological functional outcome 14 days after MCAo. Combination treatment also significantly increased the expression of Angiopoietin-1 (Ang1), Tie2 and Occludin in the IBZ (p<0.05, n=8/group). The in vitro experiments showed that combination treatment and Ang1 significantly increased capillary-like tube formation and arterial cell migration; anti-Ang1 significantly reduced combination treatment induced tube-formation and artery cell migration (p<0.05, n=6/group). These findings indicated that combination of sub-therapeutic doses of Simvastatin and HUCBCs treatment of stroke increases Ang1/Tie2 and Occludin expression in the ischemic brain, amplifies endogenous angiogenesis and arteriogenesis, and enhances vascular remodeling which in concert may contribute to functional outcome after stroke.
PMCID: PMC3505259  PMID: 23041512
Simvastatin; human umbilical cord blood cells (HUCBCs); vascular remodeling; stroke; Angiopoietin-1 (Ang1)
13.  ChIP-seq analysis of histone H3K9 trimethylation in peripheral blood mononuclear cells of membranous nephropathy patients 
Membranous nephropathy (MN), characterized by the presence of diffuse thickening of the glomerular basement membrane and subepithelial in situ immune complex disposition, is the most common cause of idiopathic nephrotic syndrome in adults, with an incidence of 5-10 per million per year. A number of studies have confirmed the relevance of several experimental insights to the pathogenesis of human MN, but the specific biomarkers of MN have not been fully elucidated. As a result, our knowledge of the alterations in histone methylation in MN is unclear. We used chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) to analyze the variations in a methylated histone (H3K9me3) in peripheral blood mononuclear cells from 10 MN patients and 10 healthy subjects. There were 108 genes with significantly different expression in the MN patients compared with the normal controls. In MN patients, significantly increased activity was seen in 75 H3K9me3 genes, and decreased activity was seen in 33, compared with healthy subjects. Five positive genes, DiGeorge syndrome critical region gene 6 (DGCR6), sorting nexin 16 (SNX16), contactin 4 (CNTN4), baculoviral IAP repeat containing 3 (BIRC3), and baculoviral IAP repeat containing 2 (BIRC2), were selected and quantified. There were alterations of H3K9me3 in MN patients. These may be candidates to help explain pathogenesis in MN patients. Such novel findings show that H3K9me3 may be a potential biomarker or promising target for epigenetic-based MN therapies.
PMCID: PMC3932972  PMID: 24345872
ChIP-seq; Epigenetics; H3K9me3; Membranous nephropathy
14.  The N-terminal 33 amino acid domain of Siva-1 is sufficient for nuclear localization 
Siva-1 induces apoptosis in multiple pathological processes and plays an important role in the suppression of tumor metastasis, protein degradation, and other functions. Although many studies have demonstrated that Siva-1 functions in the cytoplasm, a few have found that Siva-1 can relocate to the nucleus. In this study, we found that the first 33 amino acid residues of Siva-1 are required for its nuclear localization. Further study demonstrated that the green fluorescent protein can be imported into the nucleus after fusion with these 33 amino acid residues. Other Siva-1 regions and domains showed less effect on Siva-1 nuclear localization. By site-mutagenesis of all of these 33 amino acid residues, we found that mutants of the first 1-18 amino acids affected Siva-1 nuclear compartmentalization but could not complete this localization independently. In summary, we demonstrated that the N-terminal 33 amino acid residues were sufficient for Siva-1 nuclear localization, but the mechanism of this translocation needs additional investigation.
PMCID: PMC3935273  PMID: 24345910
Siva-1; Nuclear localization signal (NLS); Subcellular compartmentalization; Nuclear localization
15.  Paediatric bacterial keratitis cases in Shanghai: microbiological profile, antibiotic susceptibility and visual outcomes 
Hong, J | Chen, J | Sun, X | Deng, S X | Chen, L | Gong, L | Cao, W | Yu, X | Xu, J
Eye  2012;26(12):1571-1578.
The purpose of this study was to review the microbiological profile, in vitro antibiotic susceptibility and visual outcomes of paediatric microbial keratitis in Shanghai, China over the past 6 years.
Medical records of patients aged ≤16 years were reviewed, who were diagnosed as having bacterial keratitis between 1 January 2005 and 31 December 2010. Bacterial culture results and in vitro antibiotic susceptibility were analysed. A logistic regression analysis was conducted to evaluate the relationship between visual impairment and possible risk factors.
Eighty consecutive cases of paediatric bacterial keratitis cases were included, among which 59 were identified as having positive culture. Staphylococcus epidermidis was the most commonly isolated organism (n=23; 39.0%), followed by Streptococcus pneumoniae (n=11; 18.6%) and Pseudomonas aeruginosa (n=6; 10.2%). Antibiotic sensitivities revealed that tested bacteria had low resistance rates to fluoroquinolones and aminoglycosides (8.3–18.4% and 12.5–24.4%, respectively). Multivariate logistic regression analysis proved that visual impairment was significantly associated with Gram-negative bacterial infection (odds ratio (OR)=7.626; P=0.043) and an increasing number of resistant antibiotics (OR=0.385; P=0.040).
S. epidermidis was the most common isolated organism in Shanghai paediatric keratitis. The fluoroquinolones and aminoglycosides remained good choices for treating these patients. Gram-negative bacterial infection and an increasing number of resistant antibiotics were associated with worse visual prognoses in paediatric keratitis.
PMCID: PMC3522844  PMID: 23079751
bacterial keratitis; antibiotics; paediatrics; prognosis; susceptibility
16.  Risk of retinoblastoma is associated with a maternal polymorphism in dihydrofolatereductase (DHFR) and pre-natal folic acid intake 
Cancer  2012;118(23):5912-5919.
Incidence of unilateral retinoblastoma varies globally suggesting possible environmental contributors to disease incidence. Maternal intake of naturally occurring folate from vegetables during pregnancy is inversely associated with risk of retinoblastoma in offspring.
Using a case-control study design, we examined the association between retinoblastoma risk and maternal variations in the folate-metabolizing genes, methylenetetrahydrofolate reductase (MTHFR677C>T, rs1801133) and dihydrofolate reductase (DHFR 19base pair deletion of intron 1a [DHFR19bpdel], rs70991108). In central Mexico, we enrolled 103 mothers of children with newly diagnosed unilateral retinoblastoma and 97 control mothers who had healthy children in an IRB approved study.
Mothers were interviewed regarding perinatal characteristics including use of prenatal vitamin supplements and gave peripheral blood samples used for PCR-based genotyping of rs1801133 and rs70991108.
The risk of having a child with unilateral retinoblastoma were associated with maternal homozygosity for DHFR19bpdel (OR=3.78, 95%CI:1.89,7.55; p=0.0002), even after controlling for child’s DHFR19bpdel genotype (OR=2.81, 95%CI:1.32,5.99; p=0.0073). In a subgroup of 167 mothers with data on prenatal intake of supplements containing folic acid (a synthetic form of folate), DHFR19bpdel-associated risk was significantly elevated only among those who reported taking folic acid supplements. Maternal MTHFR genotype was unrelated to risk of having a child with retinoblastoma.
Maternal homozygosity for a polymorphism in the DHFR gene necessary for converting synthetic folic acid into biological folate is associated with increased risk for retinoblastoma. Prenatal ingestion of synthetic folic acid supplements may be associated with increased risk for early childhood carcinogenesis in a genetically susceptible subset of the population.
PMCID: PMC3434235  PMID: 22648968
DHFR; Folic Acid Intake; Retinoblastoma Risk; Childhood cancer
17.  Triptolide induces apoptosis in human leukemia cells through caspase-3-mediated ROCK1 activation and MLC phosphorylation 
Liu, L | Li, G | Li, Q | Jin, Z | Zhang, L | Zhou, J | Hu, X | Zhou, T | Chen, J | Gao, N
Cell Death & Disease  2013;4(12):e941-.
The diterpene triepoxide triptolide is a major active component of Tripterygium wilfordii Hook F, a popular Chinese herbal medicine with the potential to treat hematologic malignancies. In this study, we investigated the roles of triptolide in apoptosis and cell signaling events in human leukemia cell lines and primary human leukemia blasts. Triptolide selectively induced caspase-dependent cell death that was accompanied by the loss of mitochondrial membrane potential, cytochrome c release, and Bax translocation from the cytosol to the mitochondria. Furthermore, we found that triptolide dramatically induced ROCK1 cleavage/activation and MLC and MYPT phosphorylation. ROCK1 was cleaved and activated by caspase-3, rather than RhoA. Inhibiting MLC phosphorylation by ML-7 significantly attenuated triptolide-mediated apoptosis, caspase activation, and cytochrome c release. In addition, ROCK1 inhibition also abrogated MLC and MYPT phosphorylation. Our in vivo study showed that both ROCK1 activation and MLC phosphorylation were associated with the tumor growth inhibition caused by triptolide in mouse leukemia xenograft models. Collectively, these findings suggest that triptolide-mediated ROCK1 activation and MLC phosphorylation may be a novel therapeutic strategy for treating hematological malignancies.
PMCID: PMC3877542  PMID: 24309928
triptolide; leukemia; apoptosis; ROCK1; MLC; MYPT
18.  Accumulation of heavy metals in leaf vegetables from agricultural soils and associated potential health risks in the Pearl River Delta, South China 
This study investigated the extent of heavy metal accumulation in leaf vegetables and associated potential health risks in agricultural areas of the Pearl River Delta (PRD), South China. Total concentrations of mercury (Hg), cadmium (Cd), lead (Pb), chromium (Cr) and arsenic (As) were determined in 92 pairs of soil and leaf vegetable (flowering Chinese cabbage, lettuce, pakchoi, Chinese cabbage, loose-leaf lettuce, and Chinese leaf mustard) samples collected from seven agricultural areas (cities). The bioconcentration factors (BCF) of heavy metals from soil to vegetables were estimated, and the potential health risks of heavy metal exposure to the PRD residents through consumption of local leaf vegetables were assessed. Results showed that among the six leaf vegetables, pakchoi had the lowest capacity for heavy metal enrichment, whereas among the five heavy metals, Cd had the highest capacity for transferring from soil into vegetables, with BCF values 30-fold those of Hg and 50-fold those of Cr, Pb and As. Sewage irrigation and fertilization were likely the main sources of heavy metals accumulated in leaf vegetables grown in agricultural areas of the PRD region. Different from previous findings, soil pH had no clear effect on metal accumulation in leaf vegetables. Despite a certain degree of metal enrichment from soil to leaf vegetables, the PRD residents were not exposed to significant health risks associated with consumption of local leaf vegetables. Nevertheless, more attention should be paid to children due to their sensitivity to metal pollutants.
PMCID: PMC3902199  PMID: 24185814
Pearl River Delta; Leaf vegetables; Heavy metals; Bioconcentration factor; Target hazard quotient
19.  A Single-Day Paradigm of Self-Regulated Human Cocaine Administration 
Prior work by our group has shown the feasibility, safety, and validity of a multi-day, multi-dose paradigm of self-regulated cocaine administration in humans. The current work sought to consolidate these methods in a single-day design focused on reducing logistical complexity, decreasing research burden to human subjects, and increasing suitability for medication development designs. Methods: Eleven experienced cocaine users participated in a 6-hour, single-day design, consisting of one safety/eligibility and three experimental cocaine periods (during which subjects were allowed to self-administer 8, 16, and 32 mg/70 kg cocaine doses under a fixed-ratio 1: 5 minute timeout schedule). Changes in cocaine-induced cardiovascular response, self-administration behavior, and subjective effects were assessed. Results: Procedures were well tolerated by participants, and no significant adverse events were noted. Significant (p<0.05), changes in measures of cocaine self-administration (e.g., responses, infusions, interinfusion intervals, consumption, and plasma levels), cardiovascular response (HR), and subjective effects (“high”) were observed. In contrast, cocaine-induced increases in other vital signs (e.g., SBP, DBP) and subjective effect measures (e.g., paranoia) did not differ between doses. Conclusions: These data support the safety, tolerability and validity of our single-day design. Depending on the application, such methods may afford advantages for assessing the self-regulation of cocaine administration behavior in humans (e.g., including medication development designs).
PMCID: PMC3652339  PMID: 22922558
cocaine self-administration; human studies; self-regulation; cocaine plasma levels; subjective effects
20.  Piperlongumine induces autophagy by targeting p38 signaling 
Cell Death & Disease  2013;4(10):e824-.
Piperlongumine (PL), a natural product isolated from the plant species Piper longum L., can selectively induce apoptotic cell death in cancer cells by targeting the stress response to reactive oxygen species (ROS). Here we show that PL induces cell death in the presence of benzyloxycarbonylvalyl-alanyl-aspartic acid (O-methyl)-fluoro-methylketone (zVAD-fmk), a pan-apoptotic inhibitor, and in the presence of necrostatin-1, a necrotic inhibitor. Instead PL-induced cell death can be suppressed by 3-methyladenine, an autophagy inhibitor, and substantially attenuated in cells lacking the autophagy-related 5 (Atg5) gene. We further show that PL enhances autophagy activity without blocking autophagy flux. Application of N-acetyl-cysteine, an antioxidant, markedly reduces PL-induced autophagy and cell death, suggesting an essential role for intracellular ROS in PL-induced autophagy. Furthermore, PL stimulates the activation of p38 protein kinase through ROS-induced stress response and p38 signaling is necessary for the action of PL as SB203580, a p38 inhibitor, or dominant-negative p38 can effectively reduce PL-mediated autophagy. Thus, we have characterized a new mechanism for PL-induced cell death through the ROS-p38 pathway. Our findings support the therapeutic potential of PL by triggering autophagic cell death.
PMCID: PMC3824668  PMID: 24091667
piperlongumine; autophagy; p38; reactive oxygen species
21.  Calumenin-15 facilitates filopodia formation by promoting TGF-β superfamily cytokine GDF-15 transcription 
Feng, H | Chen, L | Wang, Q | Shen, B | Liu, L | Zheng, P | Xu, S | Liu, X | Chen, J | Teng, J
Cell Death & Disease  2013;4(10):e870-.
Filopodia, which are actin-rich finger-like membrane protrusions, have an important role in cell migration and tumor metastasis. Here we identify 13 novel calumenin (Calu) isoforms (Calu 3–15) produced by alternative splicing, and find that Calu-15 promotes filopodia formation and cell migration. Calu-15 shuttles between the nucleus and cytoplasm through interacting with importin α, Ran GTPase, and Crm1. The phosphorylation of the threonine at position 73 (Thr-73) by casein kinase 2 (CK2) is essential for the nuclear import of Calu-15, and either Thr-73 mutation or inhibition of CK2 interrupts its nuclear localization. In the nucleus, Calu-15 increases the transcription of growth differentiation factor-15 (GDF-15), a member of the transforming growth factor-β (TGF-β) superfamily, via binding to its promoter region. Furthermore, Calu-15 induces filopodia formation mediated by GDF-15. Together, we identify that Calu-15, a novel isoform of Calu with phosphorylation-dependent nuclear localization, has a critical role in promoting filopodia formation and cell migration by upregulating the GDF-15 transcription.
PMCID: PMC3920949  PMID: 24136234
calumenin-15; isoform; phosphorylation; GDF-15; transcription; filopodia
22.  Complex Relationships between Cerebral Blood Flow and Brain Atrophy in Early Huntington’s Disease 
NeuroImage  2011;59(2):1043-1051.
Alterations in cerebral blood flow (CBF) may play an important role in the pathophysiology of neurodegenerative disorders such as Huntington’s disease (HD). While a few reports have suggested reductions in CBF in HD, little is known about their extent and whether, or how, they might be related to atrophy and to clinical symptoms. We used pulsed arterial-spin labelling MRI in conjunction with high-resolution anatomical MRI to non-invasively measure regional CBF in 17 early stage HD subjects and 41 age- and gender-matched healthy controls. We found profound yet heterogeneous CBF reductions in the cortex, extending to the sensorimotor, paracentral, inferior temporal and lateral occipital regions, with sparing of the neighbouring postcentral gyrus, insula and medial occipital areas. As expected, CBF in subcortical regions was also profoundly reduced, and to a similar degree. Unexpectedly, however, the association between CBF reductions and regional atrophy was complex, the two being directly associated in certain areas but not with others. In contrast, CBF was associated with performance on the Stroop, suggesting a potentially important role for alterations in CBF in cognitive deficits in HD. The work described here may have broad-reaching implications for our understanding of HD pathogenesis, progression and emerging therapies.
PMCID: PMC3787075  PMID: 21945790
Huntington’s disease (HD); pulsed arterial-spin labelling (PASL); magnetic resonance imaging (MRI); cerebral blood flow (CBF); cortical thickness
23.  Bid Mediates Anti-Apoptotic COX-2 Induction Through the IKKβ/NFκB Pathway Due to 5-MCDE Exposure 
Current cancer drug targets  2010;10(1):96-106.
Although Bid is considered to be a cell apoptotic mediator, current studies suggest that it has a possible role in cell survival for mouse embryonic fibroblasts (MEFs) in response to low doses of anti-(±)-5- methylchrysene-l,2-diol-3,4-epoxide (<0.25µM) (5-MCDE). We found that the exposure of MEFs to 0.25 µM 5-MCDE resulted in a slight apoptotic induction, while this apoptotic response was substantially increased in the Bid knockout MEFs (Bid−/−), suggesting that there is a Bid-mediated anti-apoptotic function in this response. This notion was further supported by the findings that re-constitution expression of Bid into Bid−/− cells could inhibit the increased apoptosis. Further studies show that the antiapoptotic function of Bid was associated with its mediation of COX-2 expression. This conclusion was based the reduction of COX-2 expression in Bid−/− cells, the restoration of low sensitivity to 5-MCDE-induced apoptosis by the introduction of Bid into Bid−/− cells, and increased sensitivity of WT MEFs to 5-MCDE-induced apoptosis by the knockdown of COX-2 expression. Furthermore, we found that Bid mediated COX-2 expression through the IKKβ/NFκB pathway because the deficiency of Bid in Bid−/− MEFs resulted in the blockade of IKK/NFκB activation and knockout of IKKβ caused abrogation of COX-2 expression induced by 5-MCDE. Collectively, our results demonstrate that Bid is critical for COX-2 induction through the IKKβ/NFκB pathway, which mediates its anti-apoptotic function, in cell response to low doses of 5-MCDE exposure.
PMCID: PMC3759233  PMID: 20088789
Bid; COX-2; 5-MCDE; NFκB; apoptosis
24.  Ethnic and sex differences in bone marrow adipose tissue and bone mineral density relationship 
The relationship between bone marrow adipose tissue and bone mineral density is different between African Americans and Caucasians as well as between men and women. This suggests that the mechanisms that regulate the differentiation and proliferation of bone marrow stromal cells may differ in these populations.
It has long been established that there are ethnic and sex differences in bone mineral density (BMD) and fracture risk. Recent studies suggest that bone marrow adipose tissue (BMAT) may play a role in the pathogenesis of osteoporosis. It is unknown whether ethnic and sex differences exist in the relationship between BMAT and BMD.
Pelvic BMAT was evaluated in 455 healthy African American and Caucasian men and women (age 18–88 years) using whole-body T1-weighted magnetic resonance imaging. BMD was measured using whole-body dual-energy X-ray absorptiometry.
A negative correlation was observed between pelvic BMAT and total body BMD or pelvic BMD (r=−0.533, −0.576, respectively; P<0.001). In multiple regression analyses with BMD as the dependent variable, ethnicity significantly entered the regression models as either an individual term or an interaction with BMAT. Menopausal status significantly entered the regression model with total body BMD as the dependent variable. African Americans had higher total body BMD than Caucasians for the same amount of BMAT, and the ethnic difference for pelvic BMD was greater in those participants with a higher BMAT. Men and premeno-pausal women had higher total body BMD levels than postmenopausal women for the same amount of BMAT.
An inverse relationship exists between BMAT and BMD in African American and Caucasian men and women. The observed ethnic and sex differences between BMAT and BMD in the present study suggest the possibility that the mechanisms regulating the differentiation and proliferation of bone marrow stromal cells may differ in these populations.
PMCID: PMC3378820  PMID: 22173789
Body composition; Bone marrow; Bone mineral density; Dual-energy X-ray absorptiometry; Ethnicity; Magnetic resonance imaging; Sex
25.  Atorvastatin overcomes gefitinib resistance in KRAS mutant human non-small cell lung carcinoma cells 
Chen, J | Bi, H | Hou, J | Zhang, X | Zhang, C | Yue, L | Wen, X | Liu, D | Shi, H | Yuan, J | Liu, J | Liu, B
Cell Death & Disease  2013;4(9):e814-.
The exact influence of statins on gefitinib resistance in human non-small cell lung cancer (NSCLC) cells with KRAS mutation alone or KRAS/PIK3CA and KRAS/PTEN comutations remains unclear. This work found that transfection of mutant KRAS plasmids significantly suppressed the gefitinib cytotoxicity in Calu3 cells (wild-type KRAS). Gefitinib disrupted the Kras/PI3K and Kras/Raf complexes in Calu3 cells, whereas not in Calu3 KRAS mutant cells. These trends were corresponding to the expression of pAKT and pERK in gefitinib treatment. Atorvastatin (1 μM) plus gefitinib treatment inhibited proliferation, promoted cell apoptosis, and reduced the AKT activity in KRAS mutant NSCLC cells compared with gefitinib alone. Atorvastatin (5 μM) further enhanced the gefitinib cytotoxicity through concomitant inhibition of AKT and ERK activity. Atorvastatin could interrupt Kras/PI3K and Kras/Raf complexes, leading to suppression of AKT and ERK activity. Similar results were also obtained in comutant KRAS/PTEN or KRAS/PIK3CA NSCLC cells. Furthermore, mevalonate administration reversed the effects of atorvastatin on the Kras/Raf and Kras/PI3K complexes, as well as AKT and ERK activity in both A549 and Calu1 cells. The in vivo results were similar to those obtained in vitro. Therefore, mutant KRAS-mediated gefitinib insensitivity is mainly derived from failure to disrupt the Kras/Raf and Kras/PI3K complexes in KRAS mutant NSCLC cells. Atorvastatin overcomes gefitinib resistance in KRAS mutant NSCLC cells irrespective of PIK3CA and PTEN statuses through inhibition of HMG-CoA reductase-dependent disruption of the Kras/Raf and Kras/PI3K complexes.
PMCID: PMC3789171  PMID: 24071646
gefitinib; atorvastatin; mutant KRAS; NSCLC

Results 1-25 (432)