Xia H.,Institute of Chemical Technology |
Ng S.S.,Institute of Chemical Technology |
Jiang S.,Sun Yat Sen University |
Cheung W.K.C.,Institute of Chemical Technology |
And 5 more authors.
Biochemical and Biophysical Research Communications | Year: 2010
Nasopharyngeal carcinoma (NPC), a highly metastatic and invasive malignant tumor originating from the nasopharynx, is widely prevalent in Southeast Asia, the Middle East and North Africa. Although viral, dietary and genetic factors have been implicated in NPC, the molecular basis of its pathogenesis is not well defined. Based on a recent microRNA (miRNA) microarray study showing miR-200 downregulation in NPC, we further investigated the role of miR-200a in NPC carcinogenesis. We found that the endogenous miR-200a expression level increases with the degree of differentiation in a panel of NPC cell lines, namely undifferentiated C666-1, high-differentiated CNE-1, and low-differentiated CNE-2 and HNE1 cells. By a series of gain-of-function and loss-of-function studies, we showed that over-expression of miR-200a inhibits C666-1 cell growth, migration and invasion, whereas its knock-down stimulates these processes in CNE-1 cells. In addition, we further identified ZEB2 and CTNNB1 as the functional downstream targets of miR-200a. Interestingly, knock-down of ZEB2 solely impeded NPC cell migration and invasion, whereas CTNNB1 suppression only inhibited NPC cell growth, suggesting that the inhibitory effects of miR-200a on NPC cell growth, migration and invasion are mediated by distinct targets and pathways. Our results reveal the important role of miR-200a as a regulatory factor of NPC carcinogenesis and a potential candidate for miRNA-based therapy against NPC. © 2009 Elsevier Inc. All rights reserved.
Dong Y.,Li Ka Shing Institute of Health science |
Dong Y.,Chinese University of Hong Kong |
Zhao J.,Li Ka Shing Institute of Health science |
Wu C.-W.,Li Ka Shing Institute of Health science |
And 9 more authors.
Molecular Cancer Research | Year: 2013
Dysregulated microRNA (miRNA) expression was profiled through a miRNA array comparison between human colorectal cancer tumors and their adjacent normal tissues. Specifically, using laser capture microdissection, miR-133a was shown to be significantly downregulated in primary colorectal cancer specimens compared with matched adjacent normal tissue. Ectopic expression of miR-133a significantly suppressed colorectal cancer cell growth in vitro and in vivo. Cell-cycle analysis revealed that miR-133a induced a G0/G1- phase arrest, concomitant with the upregulation of the key G1-phase regulator p21Cip1. We further revealed that miR-133a markedly increased p53 protein and induced p21Cip1 transcription. Studies in silico revealed that the 30UTR of the ring finger and FYVE-like domain containing E3-ubiquitin protein ligase (RFFL), which regulates p53 protein, contains an evolutionarily conserved miR-133a binding site. miR-133a repressed RFFL- 30UTR reporter activity and reduced RFFL protein levels, indicating that miR-133a directly bound to RFFL mRNA and inhibited RFFL translation. Moreover, miR-133a sensitized colon cancer cells to doxorubicin and oxaliplatin by enhancing apoptosis and inhibiting cell proliferation. These data add weight to the significance of miR-133a in the development of CRC. Implications: miR-133a serves as a potential tumor suppressor upstream of p53 in colorectal cancer and may sensitize cells to therapeutics. © 2013 American Association for Cancer Research.
Wang C.C.,Chinese University of Hong Kong |
Wang C.C.,Li Ka Shing Institute of Health science |
Billett E.,Nottingham Trent University |
Borchert A.,Charité - Medical University of Berlin |
And 2 more authors.
Cellular and Molecular Life Sciences | Year: 2013
Monoamine oxidases (MAOs) are flavoproteins of the outer mitochondrial membrane that catalyze the oxidative deamination of biogenic and xenobiotic amines. In mammals there are two isoforms (MAO-A and MAO-B) that can be distinguished on the basis of their substrate specificity and their sensitivity towards specific inhibitors. Both isoforms are expressed in most tissues, but their expression in the central nervous system and their ability to metabolize monoaminergic neurotransmitters have focused MAO research on the functionality of the mature brain. MAO activities have been related to neurodegenerative diseases as well as to neurological and psychiatric disorders. More recently evidence has been accumulating indicating that MAO isoforms are expressed not only in adult mammals, but also before birth, and that defective MAO expression induces developmental abnormalities in particular of the brain. This review is aimed at summarizing and critically evaluating the new findings on the developmental functions of MAO isoforms during embryogenesis. © 2012 Springer Basel AG.
Liao G.J.W.,Li Ka Shing Institute of Health science |
Liao G.J.W.,Chinese University of Hong Kong |
Chiu R.W.K.,Li Ka Shing Institute of Health science |
Chiu R.W.K.,Chinese University of Hong Kong |
And 2 more authors.
Pathology | Year: 2012
The existence of cell free DNA derived from the fetus in the plasma of pregnant women was first demonstrated in 1997. This discovery offered the possibility of non-invasive sampling of fetal genetic material simply through the collection of a maternal blood sample. Such cell free fetal DNA molecules in the maternal circulation have subsequently been shown to originate from the placenta and could be detected from about 7 weeks of gestation. It has been shown that cell free fetal DNA analysis could offer highly accurate assessment of fetal genotype and chromosomal makeup for some applications. Thus, cell free fetal DNA analysis has been incorporated as a part of prenatal screening programs for the prenatal management of sex-linked and sex-associated diseases, rhesus D incompatibility as well as the prenatal detection of Down's syndrome. Cell free fetal DNA analysis may lead to a change in the way prenatal assessments are made. © 2012 Royal College of Pathologists of Australasia.
Tsang W.P.,Li Ka Shing Institute of Health science |
Ng E.K.O.,Institute of Digestive Disease |
Ng S.S.M.,Chinese University of Hong Kong |
Jin H.,Institute of Digestive Disease |
And 3 more authors.
Carcinogenesis | Year: 2010
H19 is an imprinted oncofetal non-coding RNA recently shown to be the precursor of miR-675. The pathophysiological roles of H19 and its mature product miR-675 to carcinogenesis have, however, not been defined. By quantitative reverse transcription-polymerase chain reaction, both H19 and miR-675 were found to be upregulated in human colon cancer cell lines and primary human colorectal cancer (CRC) tissues compared with adjacent noncancerous tissues. Subsequently, the tumor suppressor retinoblastoma (RB) was confirmed to be a direct target of miR-675 as the microRNA suppressed the activity of the luciferase reporter carrying the 3′-untranslated region of RB messenger RNA that contains the miR-675-binding site. Suppression of miR-675 by transfection with anti-miR-675 increased RB expression and at the same time, decreased cell growth and soft agar colony formation in human colon cancer cells. Reciprocally, enhanced miR-675 expression by transfection with miR-675 precursor decreased RB expression, increased tumor cell growth and soft agar colony formation. Moreover, the inverse relationship between the expressions of RB and H19/miR-675 was also revealed in human CRC tissues and colon cancer cell lines. Our findings demonstrate that H19-derived miR-675, through downregulation of its target RB, regulates the CRC development and thus may serve as a potential target for CRC therapy. © The Author 2009. Published by Oxford University Press. All rights reserved. For Permissions, please email: firstname.lastname@example.org.
Chung K.-Y.,Li Ka Shing Institute of Health science |
Chung K.-Y.,Chinese University of Hong Kong |
Cheng I.K.-C.,Li Ka Shing Institute of Health science |
Cheng I.K.-C.,Chinese University of Hong Kong |
And 7 more authors.
Hepatology | Year: 2011
Genomic amplification of regional chromosome 8q24 is a common event in human cancers. In hepatocellular carcinoma (HCC), a highly aggressive malignancy that is rapidly fatal, recurrent 8q24 gains can be detected in >50% of cases. In this study, attempts to resolve the 8q24 region by way of array comparative genomic hybridization for affected genes in HCC revealed distinctive gains of block of proliferation 1 (BOP1). Gene expression evaluation in an independent cohort of primary HCC (n = 65) revealed frequent BOP1 up-regulation in tumors compared with adjacent nontumoral liver (84.6%; P < 0.0001). Significant associations could also be drawn between increased expressions of BOP1 and advance HCC staging (P = 0.004), microvascular invasion (P = 0.006), and shorter disease-free survival of patients (P = 0.02). Examination of expression of C-MYC, a well-known oncogene located in proximity to BOP1, in the same series of primary HCC cases did not suggest strong clinicopathologic associations. Functional investigations by small interfering RNA-mediated suppression of BOP1 in HCC cell lines indicated significant inhibition on cell invasion (P < 0.005) and migration (P < 0.05). Overexpression of BOP1 in the immortalized hepatocyte cell line L02 showed increase cellular invasiveness and cell migratory rate (P < 0.0001). In both gene knockdown and ectopic expression assays, BOP1 did not exert an effect on cell viability and proliferation. Evident regression of the epithelial-mesenchymal transition (EMT) phenotype was readily identified in BOP1 knockdown cells, whereas up-regulation of epithelial markers (E-cadherin, cytokeratin 18, and γ-catenin) and down-regulation of mesenchymal markers (fibronectin and vimentin) were seen. A corresponding augmentation of EMT was indicated from the ectopic expression of BOP1 in L02. In addition, BOP1 could stimulate actin stress fiber assembly and RhoA activation. Conclusion: Our findings underline an important role for BOP1 in HCC invasiveness and metastasis potentials through inducing EMT and promoting actin cytoskeleton remodeling. © 2011 American Association for the Study of Liver Diseases.
Tsui N.B.Y.,Li Ka Shing Institute of Health science |
Tsui N.B.Y.,Chinese University of Hong Kong |
Kadir R.A.,Royal Free Hospital |
Chan K.C.A.,Li Ka Shing Institute of Health science |
And 10 more authors.
Blood | Year: 2011
Hemophilia is a bleeding disorder with X-linked inheritance. Current prenatal diagnostic methods for hemophilia are invasive and pose a risk to the fetus. Cell-free fetal DNA analysis in maternal plasma provides a noninvasive mean of assessing fetal sex in such pregnancies. However, the disease status of male fetuses remains unknown if mutation-specific confirmatory analysis is not performed. Here we have developed a noninvasive test to diagnose whether the fetus has inherited a causative mutation for hemophilia from its mother. The strategy is based on a relative mutation dosage approach, which we have previously established for determining the mutational status of fetuses for autosomal disease mutations. In this study, the relative mutation dosage method is used to deduce whether a fetus has inherited a hemophilia mutation on chromosome X by detecting whether the concentration of the mutant or wild-type allele is overrepresented in the plasma of heterozygous women carrying male fetuses. We correctly detected fetal genotypes for hemophilia mutations in all of the 12 studied maternal plasma samples obtained from at-risk pregnancies from as early as the 11th week of gestation. This development would make the decision to undertake prenatal testing less traumatic and safer for at-risk families. © 2011 by The American Society of Hematology.
Wong F.C.K.,Li Ka Shing Institute of Health science |
Wong F.C.K.,Chinese University of Hong Kong |
Lo Y.M.D.,Li Ka Shing Institute of Health science |
Lo Y.M.D.,Chinese University of Hong Kong
Annual Review of Medicine | Year: 2016
Noninvasive prenatal testing (NIPT) is accomplished by analysis of circulating cell-free fetal nucleic acids in maternal plasma. The advent of massively parallel sequencing (MPS) has enabled NIPT of chromosomal aneuploidies with unprecedented robustness, and these tests are now widely available for clinical use. Moreover, MPS-based NIPT of subchromosomal deletions/duplications and single-gene disorders has also been achieved, and the number of applications is growing. In addition to specific fetal genetic disorders, the whole fetal genome, transcriptome, and methylome have been revealed by deep sequencing of maternal plasma. The analysis of the fetal transcriptome and methylome may yield valuable information on fetal and maternal health. With continued improvement in sequencing technology and reduction in sequencing costs, the analysis of cell-free nucleic acids would play an increasingly important role in prenatal screening, diagnosis, monitoring, and risk stratification of fetal as well as maternal conditions. © 2016 by Annual Reviews.
Lam K.-W.G.,Li Ka Shing Institute of Health science |
Lam K.-W.G.,Chinese University of Hong Kong |
Jiang P.,Li Ka Shing Institute of Health science |
Jiang P.,Chinese University of Hong Kong |
And 9 more authors.
Clinical Chemistry | Year: 2012
BACKGROUND: A genomewide genetic and mutational profile of a fetus was recently determined via deep sequencing of maternal plasma DNA. This technology could have important applications for noninvasive prenatal diagnosis (NIPD) of many monogenic diseases. Relative haplotype dosage(RHDO)analysis, a core step of this procedure, would allow one to elucidate the maternally inherited half of the fetal genome. For clinical applications, the cost and complexity of data analysis might be reduced via targeted application of this approach to selected genomic regions containing disease-causing genes. There is thus a need to explore the feasibility of performing RHDO analysis in a targeted manner. METHODS: We performed target enrichment by using solution-phase hybridization followed by massively parallel sequencing of the β-globin gene region in 2 families undergoing prenatal diagnosis for β-thalassemia. We used digital PCR strategies to physically deduce parental haplotypes. Finally, we performed RHDO analysis with target-enriched sequencing data and parental haplotypes to reveal the β-thalassemic status for the fetuses. RESULTS: A mean sequencing depth of 206-fold was achieved in the β-globin gene region by targeted sequencing of maternal plasma DNA. RHDO analysis was successful for the sequencing data obtained from the target-enriched samples, including a region in one of the families in which the parents had similar haplotype structures. Data analysis revealed that both fetuses were heterozygous carriers of β-thalassemia. CONCLUSIONS: Targeted sequencing of maternal plasma DNA for NIPD of monogenic diseases is feasible. © 2012 American Association for Clinical Chemistry.
Dennis Lo Y.,Li Ka Shing Institute of Health science |
Dennis Lo Y.,Chinese University of Hong Kong |
Chiu R.W.,Li Ka Shing Institute of Health science |
Chiu R.W.,Chinese University of Hong Kong
Journal of Pathology | Year: 2011
Over the past 15 years there has been increasing interest in the biology and diagnostic applications of circulating DNA in the plasma of human subjects. In particular, DNA from a fetus, a tumour, a transplanted organ and injured tissues has been found in the plasma of pregnant women, cancer patients, transplant recipients and patients suffering from multiple pathologies, respectively. The advent of massively parallel sequencing has given us a quantitative and powerful tool for studying circulating DNA on a genome-wide level. Using this approach, fetal chromosomal aneuploidies can be robustly detected using maternal plasma. Furthermore, a genome-wide genetic map of a fetus can also be constructed using this approach. This method has also allowed one to identify tumour-associated chromosomal translocations, which can then be detected in plasma. The direct application of massively parallel sequencing to the serum of cancer patients has also allowed quantitative aberrations that are associated with malignancy to be detected in serum. The use of massively parallel sequencing on the plasma of transplantation recipients has opened up an approach for detecting rejection. The application of circulating DNA sequencing has also opened up a new method for elucidating the quantitative aberration of circulating DNA in many pathological conditions. Such developments would provide new modalities for molecular diagnostics and would improve our understanding of the biology of circulating nucleic acids. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.