Marie C Lin

Prince of Wales Hospital, Hong Kong, Chiu-lung, Kowloon City, Hong Kong

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Publications (65)304.5 Total impact

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    ABSTRACT: MicroRNAs (miRNAs) are small, non-coding RNAs which regulate gene expression at the post-transcriptional level. Abnormal expression of miRNAs occurs frequently in human tumors. Despite the fact that reduced expression of miR-128 has been observed in glioma tissues and cells, the role of miR-128 in tumors has not been fully characterized. In the present study, cell adhesion assays indicated that overexpression of miR-128 can promote cell-cell adhesion. Target site prediction algorithms indicated that miR-128 binds the 3'-untranslated regions of erythropoietin-producing hepatocellular receptor (Eph)B1 and EphB2 mRNAs. Luciferase reporter assays confirmed that miR-128 binds and regulates EphB1 and EphB2 mRNAs. Overexpression of EphB2 reduced the ability of miR-128 to promote cell-cell adhesion. The wound-healing assay indicated that miR-128 significantly inhibited cell migration via EphB2. This study revealed the novel functions of miR-128 in cell-cell adhesion and cell migration in glioma cells through the regulation of EphB2, and identified EphB1 and EphB2 as novel miR-128 targets.
    Oncology Reports 07/2013; · 2.30 Impact Factor
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    ABSTRACT: The recombinant adenovirus is evolving as a promising gene delivery vector for gene therapy due to its efficiency in transducing different genes into most types of cells. However, the host-immune response elicited by primary inoculation of an adenovirus can cause rapid clearance of the vector, impairing the efficacy of the adenovirus and hence obstructing its clinical application. We have previously synthesized a biodegradable co-polymer consisting of a low molecular weight PEI (MW 600 Da), cross-linked with β-cyclodextrin, and conjugated with folic acid (PEI-CyD-FA, named H1). Here we report that coating the adenovirus vector (Adv) with H1 (H1/rAdv) could significantly improve both the efficacy and biosafety of Adv. Enhanced transfection efficiency as well as prolonged duration of gene expression were clearly demonstrated either by intratumoral or systemic injection of a single dose of H1/rAdv in immunocompetent mice. Importantly, repeated injections of H1/rAdv did not reduce the transfection efficiency in immunocompetent mice. Furthermore, H1 transformed the surface charge of the adenovirus capsomers from negative to positive in physiological solution, suggesting that H1 coated the capsid protein of the adenovirus. This could shelter the epitopes of capsid proteins of the adenovirus, resulting in a reduced host-immune response and enhanced transfection efficiency. Taken together, these findings suggest that H1/rAdv is an effective gene delivery system superior to the adenovirus alone and that it could be considered as a preferred vehicle for gene therapy.
    Current Medicinal Chemistry 03/2013; · 4.07 Impact Factor
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    ABSTRACT: Chemoradiotherapy (CRT) is a standard treatment for esophageal squamous cell carcinoma (ESCC) in its advanced stages. The telomerase/telomere interacting protein PinX1 contributes to telomere maintenance, tumorigenicity and influences the DNA damage agents-induced apoptotic response in telomerase-positive cancer cells. However, the clinical and biological significance of PinX1 in human ESCCs remains unclear. We examined the expression dynamics of PinX1 by immunohistochemistry in a learning cohort (n = 98) and a validation cohort (n = 59) of ESCC patients treated with definite chemoradiotherapy (CRT). A series of in vivo and in vitro assays were performed to elucidate the effect of PinX1 on ESCC cells CRT response and underlying mechanisms. Knockdown of PinX1 did not affect ESCC cells chemosensitivities to 5-fluorouracil and cisplatin, but substantially increased ESCC cells therapeutic efficacy of radiation both in vitro and in vivo. Ectopic overexpression of PinX1 dramatically enhanced ESCC cells resistance to radiotherapy. Furthermore, we demonstrated that PinX1 resistance to radiotherapy (RT) was attributed to PinX1 maintaining telomere stability, reducing ESCC cell death by RT-induced mitosis catastrophe (MC). High expression of Pinx1 correlated positively with ESCC's resistance to CRT, and was a strong and independent predictor for short disease-specific survival (DSS) of ESCC patients. Our data suggests that PinX1 could be served as a novel predictor for a CRT response to ESCC patients, and the pathway of PinX1-mediated telomere stability might represent a new target to improve the RT effect of ESCC. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
    The Journal of Pathology 01/2013; · 7.59 Impact Factor
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    ABSTRACT: Gliomas are the most common and aggressive primary tumors in the central nervous system. Recently, Max interactor-1 (MXI1), an antagonist of c-Myc that is involved in brain tumor progression, has been reported to be deregulated in a variety of tumors including glioma. However, the mechanism of MXI1 deregulation in gliomas remains unclear. In this study, we show that the relative expression level of MXI1 is markedly down-regulated in glioma cell lines. Using integrated bioinformatic analysis and experimental confirmation, we identified several miRNAs by screening a panel of predicted miRNAs that may regulate the MXI1 3'UTR. The strongest inhibitory miRNA, miR-155, can attenuate the activity of a luciferase reporter gene that is fused with the MXI1 3'UTR and decrease the expression levels of MXI1 mRNA and protein in U87 glioma cells. The potential role of miR-155 in promoting glioma cell proliferation by targeting MXI1 was confirmed in various glioma cell lines by rescue experiments using MTT assays, EdU incorporation assay, and cell counting experiments. In addition, we determined that the level of MXI1 mRNA was inversely correlated with the expression of miR-155 in 18 sets of glioblastoma multiforme specimens. These findings reveal for the first time that the targeting of MXI1 by miR-155 may result in a reduction in MXI1 expression and promote glioma cell proliferation; this result suggests a novel function of miR-155 in targeting MXI1 in glioma-genesis.
    PLoS ONE 01/2013; 8(12):e83055. · 3.73 Impact Factor
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    ABSTRACT: MiR-145 is known as a tumor suppressor in numerous human cancers. However, its role in tumor angiogenesis remains poorly defined. In this study, we found that miR-145 was significantly downregulated in breast cancer tissues by using 106 cases of normal and cancer tissues as well as in breast cancer cells. MiR-145 exhibited inhibitory role in tumor angiogenesis, cell growth and invasion and tumor growth through the post-transcriptional regulation of the novel targets N-RAS and VEGF-A. In addition, we provide evidence that the expression levels of miR-145 correlate inversely with malignancy stages of breast tumors, although there is no association between miR-145 levels and hormone receptor levels in breast cancer. Taken together, these results demonstrate that miR-145 plays important inhibitory role in breast cancer malignancy by targeting N-RAS and VEGF-A, which may be potential therapeutic and diagnostic targets.
    Cell cycle (Georgetown, Tex.) 06/2012; 11(11):2137-45. · 5.24 Impact Factor
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    ABSTRACT: In this study we describe a novel polymer, mPPS-FA, synthesized as a potential gene transfer vector. To complete mPPS-FA, folic acid was conjugated to a backbone (named mPPS) consisting of a copolymer of methyl PEG-2000, PEI-600, and sebacoyl chloride. (1)H NMR, FT-IR, and UV spectroscopy were used to characterize the structure of mPPS-FA. It was revealed that mPPS-FA holds the ability to bind plasmid DNA yielding positively charged particles (polyplexes). Dynamic light scattering (DLS) and TEM techniques were used to study the size and morphology of the formed mPPS-FA/DNA nanocomplexes. The mPPS-FA/DNA nanoparticles exhibited low cytotoxicity as transfection of B16-F0, U87MG, CHO-1, and Ho-8910 cells produced >80% viability indicating low cytotoxicity of the polymer. The ability of mPPS-FA to deliver EGFP plasmid to melanoma B16-F0, U87, CHO-1, Ho-8910, and A549 cells was investigated in vitro as compared to the lipid-based transfection agent Lipofectamine2000 and Linear PEI 22 kDa (L-PEI 22 kDa). We found that mPPS-FA/DNA complexes yielded the highest GFP transfection efficiency in B16-F0, U87, CHO-1, and Ho-8910 cells, which all highly express folate receptors (FR), at an mPPS-FA/DNA ratio (w/w) of 15. Furthermore, the transfection of mPPS-FA/DNA complexes in CHO-1 cells could be competitively blocked by free folic acid molecules. In contrast, in low FR expressing A549 cells, mPPS-FA showed similar low transfection efficiency as mPPS. Taken together, mPPS-FA showed the highest efficiency in vitro and the potential to be developed as a nonviral gene carrier.
    International journal of pharmaceutics 04/2012; 426(1-2):182-92. · 2.96 Impact Factor
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    ABSTRACT: The recent outbreak of enterovirus 71 (EV71) infected millions of children and caused over 1,000 deaths. To date, neither an effective vaccine nor antiviral treatment is available for EV71 infection. Interferons (IFNs) have been successfully applied to treat patients with hepatitis B and C viral infections for decades but have failed to treat EV71 infections. Here, we provide the evidence that EV71 antagonizes type I IFN signaling by reducing the level of interferon receptor 1 (IFNAR1). We show that the host cells could sense EV71 infection and stimulate IFN-β production. However, the induction of downstream IFN-stimulated genes is inhibited by EV71. Also, only a slight interferon response and antiviral effects could be detected in cells treated with recombinant type I IFNs after EV71 infection. Further studies reveal that EV71 blocks the IFN-mediated phosphorylation of STAT1, STAT2, Jak1, and Tyk2 by reducing IFNAR1. Finally, we identified the 2A protease encoded by EV71 as an antagonist of IFNs and show that the protease activity is required for reducing IFNAR1 levels. Taken together, our study for the first time uncovers a mechanism used by EV71 to antagonize type I IFN signaling and provides new targets for future antiviral strategies.
    Journal of Virology 01/2012; 86(7):3767-76. · 5.08 Impact Factor
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    ABSTRACT: miR-124 is a brain-enriched microRNA that plays a crucial role in neural development and has been shown to be down-regulated in glioma and medulloblastoma, suggesting its possible involvement in brain tumor progression. Here, we show that miR-124 is down-regulated in a panel of different grades of glioma tissues and in all of the human glioma cell lines we examined. By integrated bioinformatics analysis and experimental confirmation, we identified SNAI2, which is often up-regulated in glioma, as a direct functional target of miR-124. Because SNAI2 has been shown to regulate stem cell functions, we examined the roles of miR-124 and SNAI2 in glioma cell stem-like traits. The results showed that overexpression of miR-124 and knockdown of SNAI2 reduced neurosphere formation, CD133(+) cell subpopulation, and stem cell marker (BMI1, Nanog, and Nestin) expression, and these effects could be rescued by re-expression of SNAI2. Furthermore, enhanced miR-124 expression significantly inhibited glioma cell invasion in vitro. Finally, stable overexpression of miR-124 and knockdown of SNAI2 inhibited the tumorigenicity and invasion of glioma cells in vivo. These findings reveal, for the first time, that the tumor suppressor activity of miR-124 could be partly due to its inhibitory effects on glioma stem-like traits and invasiveness through SNAI2.
    Journal of Biological Chemistry 01/2012; 287(13):9962-71. · 4.65 Impact Factor
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    ABSTRACT: miR-124 is a brain-enriched miRNA that plays crucial role in neural development and has been shown to be downregulated in glioma and medulloblastoma, suggesting its possible involvement in brain tumor progression. Here we show that miR-124 is down-regulated in a panel of different grades of glioma tissues and all of the human glioma cell lines we examined. By integrated bioinformatics analysis and experimental confirmation, we identified SNAI2, which is often upregulated in glioma, as a direct functional target of miR-124. Since SNAI2 has been shown to regulate stem cell functions, we examined the roles of miR-124 and SNAI2 in glioma stem-like cell traits. The results showed that overexpression of miR-124 and knockdown of SNAI2 reduced neurosphere formation, CD133+ cell subpopulation and stem cell markers (BMI1, Nanog and Nestin) expressions, and these effects could be rescued by re-expression of SNAI2. Furthermore, enhanced miR-124 expression significantly inhibited glioma cell invasion in vitro. Finally, stable overexpression of miR-124 and knockdown of SNAI2 inhibited the tumorigenicity and invasion of glioma cells in vivo. These findings reveal for the first time the tumor suppressor activity of miR-124 could be partly due to its inhibitory effects on glioma stem-like traits and invasiveness through SNAI2.
    Journal of Biological Chemistry 01/2012; · 4.65 Impact Factor
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    ABSTRACT: Nasopharyngeal carcinoma (NPC) is a highly malignant cancer with local invasion and early distant metastasis. NPC is highly prevalent in the Southern China and South-eastern Asia. The genetic susceptibility, endemic environment factors, and Epstein-Barr virus (EBV) infection are believed to be the major etiologic factors of NPC. Once metastasis occurs, the prognosis is very poor. It is urgently needed to develop biomarkers for early clinical diagnosis/prognosis, and novel effective therapies for nasopharyngeal carcinoma. In this paper, we systematically reviewed the current progress of miRNA studies in NPC. It has been shown that both host encoded miRNAs and EBV encoded miRNAs play key roles in almost all the steps of epithelia cell carcinogenesis, including epithelial-mesenchymal to stem-like transition, cell growth, migration, invasion, and tumorigenesis. More importantly, some miRNAs could be secreted out and play a role in the microenvironments. The level of sera miRNAs is correlated with the copy numbers of host miRNAs in tumor biopsies. Promising results of gene therapy have been also achieved by lentiviral delivered miRNAs. Taken together, cell free miRNAs would be potential biomarkers of early clinical diagnosis/prognosis; while some miRNAs could be further developed into therapeutic agents in the future.
    Biochimica et Biophysica Acta 09/2011; 1825(1):1-10. · 4.66 Impact Factor
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    ABSTRACT: The authors have previously isolated a putative oncogene, eukaryotic initiation factor 5A2 (EIF5A2) from 3q26. In this study, EIF5A2 was characterised for its role in colorectal carcinoma (CRC) aggressiveness and underlying molecular mechanisms. The expression dynamics of EIF5A2 were examined by immunohistochemistry in a cohort of carcinomatous and non-neoplastic colorectal tissues and cells. A series of in-vivo and in-vitro assays was performed to elucidate the function of EIF5A2 in CRC and its underlying mechanisms. The overexpression of EIF5A2 was examined by immunohistochemistry in 102/229 (44.5%) CRC patients, and it was significantly correlated with tumour metastasis and determined to be an independent predictor of shortened survival (p<0.05). Ectopic overexpression of EIF5A2 in CRC cells enhanced cell motility and invasion in vitro and tumour metastasis in vivo, and induced epithelial-mesenchymal transition (EMT). The depletion of EIF5A2 expression prevented CRC cell invasiveness and inhibited EMT. Importantly, the metastasis-associated protein 1 (MTA1) gene was identified as a potential downstream target of EIF5A2 in CRC cells, and knockdown of MTA1 eliminated the augmentation of carcinoma cell migration, invasion and EMT by ectopic EIF5A2. The overexpression of EIF5A2 in CRC cells substantially enhanced the enrichment of c-myc on the promoter of MTA1, and MTA1 upregulation by EIF5A2 was partly dependent on c-myc. The data suggest that EIF5A2 plays an important oncogenic role in CRC aggressiveness by the upregulation of MTA1 to induce EMT, and EIF5A2 could be employed as a novel prognostic marker and/or effective therapeutic target for CRC.
    Gut 08/2011; 61(4):562-75. · 10.73 Impact Factor
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    ABSTRACT: Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide. It is more prevalent in men than women. Related to this, recent genetic studies have revealed a causal role for androgen receptor (AR) in hepatocarcinogenesis, but the underlying molecular mechanism remains unclear. Here, we used genome-wide location and functional analyses to identify a critical mediator of AR signaling - cell cycle-related kinase (CCRK) - that drives hepatocarcinogenesis via a signaling pathway dependent on β-catenin and T cell factor (TCF). Ligand-bound AR activated CCRK transcription and protein expression via direct binding to the androgen-responsive element of the CCRK promoter in human HCC cell lines. In vitro analyses showed that CCRK was critical in human cell lines for AR-induced cell cycle progression, hepatocellular proliferation, and malignant transformation. Ectopic expression of CCRK in immortalized human liver cells activated β-catenin/TCF signaling to stimulate cell cycle progression and to induce tumor formation, as shown in both xenograft and orthotopic models. Conversely, knockdown of CCRK decreased HCC cell growth, and this could be rescued by constitutively active β-catenin or TCF. In primary human HCC tissue samples, AR, CCRK, and β-catenin were concordantly overexpressed in the tumor cells. Furthermore, CCRK overexpression correlated with the tumor staging and poor overall survival of patients. Our results reveal a direct AR transcriptional target, CCRK, that promotes hepatocarcinogenesis through the upregulation of β-catenin/TCF signaling.
    The Journal of clinical investigation 08/2011; 121(8):3159-75. · 15.39 Impact Factor
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    ABSTRACT: Recent profile studies of microRNA (miRNA) expression have documented a deregulation of miRNA (miR-124) in hepatocellular carcinoma (HCC). To determine the status of miR-124 expression and its underlying mechanisms in the pathogenesis of HCC. The expression levels of miR-124 were first examined in HCC cell lines and tumour tissues by real-time PCR. The in vitro and in vivo functional effect of miR-124 was examined further. A luciferase reporter assay was conducted to confirm target associations. The expression levels of miR-124 were frequently reduced in HCC cells and tissues, and low-level expression of miR-124 was significantly associated with a more aggressive and/or poor prognostic phenotype of patients with HCC (p<0.05). In HCC cell lines, stable overexpression of miR-124 was sufficient to inhibit cell motility and invasion in vitro, and suppress intrahepatic and pulmonary metastasis in vivo. In addition, ectopic overexpression of miR-124 in HCC cells inhibited epithelial-mesenchymal cell transition, formation of stress fibres, filopodia and lamellipodia. Further studies showed that miR-124 could directly target the 3'-untranslated region (3'-UTR) of both ROCK2 and EZH2 mRNAs, and suppress their mRNA and protein expressions. These findings suggest that miR-124 plays a critical role in regulating cytoskeletal events and epithelial-mesenchymal cell transition and, ultimately, inhibits the invasive and/or metastatic potential of HCC, probably by its direct target on ROCK2 and EZH2 genes. These results provide functional and mechanistic links between the tumour suppressor miRNA-124 and the two oncogenes ROCK2 and EZH2 on the aggressive nature of HCC. These data highlight an important role for miR-124 in the regulation of invasion and metastasis in the molecular aetiology of HCC, and suggest a potential application of miR-124 in prognosis prediction and cancer treatment.
    Gut 06/2011; 61(2):278-89. · 10.73 Impact Factor
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    ABSTRACT: Interleukin-2 (IL-2) has been shown to possess antitumor activity in numerous preclinical and clinical studies. However, the short half-life of recombinant IL-2 protein in serum requires repeated high-dose injections, resulting in severe side effects. Although adenovirus-mediated IL-2 gene therapy has shown antitumor efficacy, the host antibody response to adenoviral particles and potential biosafety concerns still obstruct its clinical applications. Here we report a novel nanopolymer for IL-2 delivery, consisting of low molecular weight polyethylenimine (600 Da) linked by β-cyclodextrin and conjugated with folate (named H1). H1 was mixed with IL-2 plasmid to form H1/pIL-2 polyplexes of around 100 nm in diameter. Peritumoral injection of these polyplexes suppressed the tumor growth and prolonged the survival of C57/BL6 mice bearing B16-F1 melanoma grafts. Importantly, the antitumor effects of H1/pIL-2 (50 μg DNA) were similar to those of recombinant adenoviruses expressing IL-2 (rAdv-IL-2; 2 × 10(8) pfu). Furthermore, we showed that H1/pIL-2 stimulated the activation and proliferation of CD8+, CD4+ T cell, and natural killer cells in peripheral blood and increased the infiltration of CD8+, CD4+ Tcells, and natural killer cells into the tumor environment. In conclusion, these results show that H1/pIL-2 is an effective and safe melanoma therapeutic with an efficacy comparable to that of rAdv-IL-2. This treatment represents an alternative gene therapy strategy for melanoma.
    Molecular Cancer Therapeutics 06/2011; 10(6):1082-92. · 5.60 Impact Factor
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    ABSTRACT: A previous study of ours indicated that enhancer of zeste homologue 2 (EZH2) plays an important role in hepatocellular carcinoma (HCC) tumorigenesis. The aim of the present study was to investigate the potential diagnostic utility of EZH2 in HCC. Immunohistochemistry was performed to examine the expression dynamics of EZH2 in two independent surgical cohorts of HCC and non-malignant liver tissues to develop a diagnostic yield of EZH2, HSP70 and GPC3 for HCC detection. The diagnostic performances of EZH2 and a three-marker panel in HCC were re-evaluated by using an additional biopsy cohort. Immunohistochemistry analysis demonstrated that the sensitivity and specificity of EZH2 for HCC detection was 95.8% and 97.8% in the testing cohort. Similar results were confirmed in the validation cohort. For diagnosis of well-differentiated HCCs, the sensitivity and specificity were 68.9% and 91.5% for EZH2, 62.5% and 98.5% for HSP70, 50.0% and 92.1% for GPC3, and 75.0% and 100% for a three-marker panel. In biopsies, positive cases for at least one marker increased from large regenerative nodule and hepatocellular adenoma (0/12) to focal nodular hyperplasia (2/20), dysplastic nodule (7/25), well-differentiated HCC (16/18) and moderately and poorly differentiated HCC (54/54). When at least two positive markers were considered, regardless of their identity, the positive cases were detected in 0/12 large regenerative nodules and hepatocellular adenomas, 0/20 focal nodular hyperplasias, 0/25 dysplastic nodules, 11/18 well-differentiated HCCs, 32/37 moderately differentiated HCCs and 15/17 poorly differentiated HCCs. Our findings suggest that EZH2 protein, as examined by immunohistochemistry, may serve as a promising diagnostic biomarker of HCCs, and the use of a three-marker panel (EZH2, HSP70 and GPC3) can improve the rate of detection of HCCs in liver biopsy tissues.
    Gut 02/2011; 60(7):967-76. · 10.73 Impact Factor
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    ABSTRACT: To investigate expression, regulation, potential role and targets of miR-195 and miR-497 in breast cancer. The expression patterns of miR-195 and miR-497 were initially examined in breast cancer tissues and cell lines by Northern blotting and quantitative real-time PCR. Combined bisulfite restriction analysis and bisulfite sequencing were carried out to study the DNA methylation status of miR-195 and miR-497 genes. Breast cancer cells stably expressing miR-195 and miR-497 were established to study their role and targets. Finally, normal, fibroadenoma and breast cancer tissues were employed to analyze the correlation between miR-195/497 levels and malignant stages of breast tumor tissues. MiR-195 and miR-497 were significantly downregulated in breast cancer. The methylation state of CpG islands upstream of the miR-195/497 gene was found to be responsible for the downregulation of both miRNAs. Forced expression of miR-195 or miR-497 suppressed breast cancer cell proliferation and invasion. Raf-1 and Ccnd1 were identified as novel direct targets of miR-195 and miR-497. miR-195/497 expression levels in clinical specimens were found to be correlated inversely with malignancy of breast cancer. Our data imply that both miR-195 and miR-497 play important inhibitory roles in breast cancer malignancy and may be the potential therapeutic and diagnostic targets.
    Clinical Cancer Research 02/2011; 17(7):1722-30. · 7.84 Impact Factor
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    ABSTRACT: The emerging concept of generating cancer stem cells from epithelial-mesenchymal transition has attracted great interest; however, the factors and molecular mechanisms that govern this putative tumor-initiating process remain largely elusive. We report here that miR-200a not only regulates epithelial-mesenchymal transition but also stem-like transition in nasopharyngeal carcinoma cells. We first showed that stable knockdown of miR-200a promotes the transition of epithelium-like CNE-1 cells to the mesenchymal phenotype. More importantly, it also induced several stem cell-like traits, including CD133(+) side population, sphere formation capacity, in vivo tumorigenicity in nude mice, and stem cell marker expression. Consistently, stable overexpression of miR-200a switched mesenchyme-like C666-1 cells to the epithelial state, accompanied by a significant reduction of stem-like cell features. Furthermore, in vitro differentiation of the C666-1 tumor sphere resulted in diminished stem-like cell population and miR-200a induction. To investigate the molecular mechanism, we demonstrated that miR-200a controls epithelial-mesenchymal transition by targeting ZEB2, although it regulates the stem-like transition differentially and specifically by β-catenin signaling. Our findings reveal for the first time the function of miR-200a in shifting nasopharyngeal carcinoma cell states via a reversible process coined as epithelial-mesenchymal to stem-like transition through differential and specific mechanisms.
    Journal of Biological Chemistry 11/2010; 285(47):36995-7004. · 4.65 Impact Factor
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    ABSTRACT: The emerging concept of generating cancer stem cells from epithelial-mesenchymal transition has attracted great interest; however, the factors and molecular mechanisms that govern this putative tumor-initiating process remain largely elusive. We report here that miR-200a not only regulates epithelial-mesenchymal transition but also stem-like transition in nasopharyngeal carcinoma cells. We first showed that stable knockdown of miR-200a promotes the transition of epithelium-like CNE-1 cells to the mesenchymal phenotype. More importantly, it also induced several stem cell-like traits, including CD133+ side population, sphere formation capacity, in vivo tumorigenicity in nude mice, and stem cell marker expression. Consistently, stable overexpression of miR-200a switched mesenchyme-like C666-1 cells to the epithelial state, accompanied by a significant reduction of stem-like cell features. Furthermore, in vitro differentiation of the C666-1 tumor sphere resulted in diminished stem-like cell population and miR-200a induction. To investigate the molecular mechanism, we demonstrated that miR-200a controls epithelial-mesenchymal transition by targeting ZEB2, although it regulates the stem-like transition differentially and specifically by β-catenin signaling. Our findings reveal for the first time the function of miR-200a in shifting nasopharyngeal carcinoma cell states via a reversible process coined as epithelial-mesenchymal to stem-like transition through differential and specific mechanisms.
    Journal of Biological Chemistry 11/2010; 285(47):36995-37004. · 4.65 Impact Factor
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    ABSTRACT: zMicroRNAs (miRNAs) are endogenously expressed small noncoding RNAs that regulate approximately one-third of human genes at post-transcription level. Previous studies have shown that miRNAs were implicated in many cellular processes and participated in the progress of various tumors including hepatocellular carcinoma (HCC). Among all miRNAs, the let-7 family is well recognized to play pivotal roles in tumorigenesis by functioning as potential growth suppressor. In the present study, we aimed to investigate the role of let-7 family, particularly the hsa-let-7g, in the molecular pathogenesis of HCC. By use of MTT, qPCR, Western blotting and 2-dimensional electrophoresis (2-DE), over-expression of hsa-let-7g was found to inhibit the proliferation of HCC cell line via negative and positive regulations of c-Myc and p16(INK4A) , respectively. The expression of hsa-let-7g was noted to be markedly lowered in the HepG2, Hep3B and Huh7 cells, yet higher in the Bel-7404 HCC cell line. Proliferation of HCC cell line was significantly inhibited after the transfection of hsa-let-7g mimics, while hsa-let-7g inhibitor transfection exerted an opposite effect. Concurrently, the mRNA and protein levels of c-Myc were found significantly decreased in HepG2 cells after transfection of hsa-let-7g mimics, but obviously increased in Bel-7404 cells after transfection of hsa-let-7g inhibitor. As revealed by 2-DE, a significant upregulation of p16(INK4A) was revealed after the gain-of-function study using hsa-let-7g. Therefore, we suggest that hsa-let-7g may act as a tumor suppressor gene that inhibits HCC cell proliferation by downregulating the oncogene, c-Myc, and upregulating the tumor suppressor gene, p16(INK4A) .
    International Journal of Cancer 03/2010; 128(2):319-31. · 6.20 Impact Factor
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    ABSTRACT: hTERTC27 is a 27 kDa C-terminal polypeptide of human telomerase reverse transcriptase that has previously been shown to reduce tumorigenicity of HeLa cells and suppress growth of xenografted glioblastoma in nude mice. Although ectopic expression of hTERTC27 upregulated genes that are involved in apoptosis, cell cycle, and immune response, the mechanism for hTERTC27-induced tumor suppression has not been completely elucidated. Since hTERT was identified as a universal tumor-associated antigen, we hypothesize that hTERTC27 inhibits tumor growth in vivo through activation of anti-tumor immune response. Immunocompetent C57BL/6 mice were used for mouse B16 melanoma model. Mice bearing B16 melanoma were administered rAAV-/rAdv viral cocktail expressing hTERTC27, and tumor growth was monitored after viral cocktail treatment. Blood and splenocytes were used to determine the level of cytokines and the activity of immune cells, respectively. B16 tumor growth was significantly inhibited by subcutaneous administration of a single dose of 1.5×10(11) vg rAAV-hTERTC27 and 2.5×10(9) pfu rAdv-hTERTC27 viral cocktail (rAAV-/rAdv-hTERTC27). The population and cytotoxicity of NK cells in the mice were significantly augmented by rAAV-/rAdv-hTERTC27 treatment, and selective depletion of the NK cell population in mice by intraperitoneal injection of anti-GM1 antibody abrogated the growth suppression of melanoma induced by rAAV-/rAdv-hTERTC27 administration. Activation of NK cells by administration of rAAV-/rAdv-hTERTC27 is critical for growth suppression of melanoma in mouse model.
    PLoS ONE 01/2010; 5(9):e12705. · 3.73 Impact Factor

Publication Stats

1k Citations
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304.50 Total Impact Points

Institutions

  • 2013
    • Prince of Wales Hospital, Hong Kong
      Chiu-lung, Kowloon City, Hong Kong
  • 2009–2013
    • Sun Yat-Sen University
      • • State Key Laboratory of Oncology
      • • School of Life Sciences
      Guangzhou, Guangdong Sheng, China
  • 2012
    • Shenzhen Center for Disease Control and Prevention
      Bao'an, Guangdong, China
  • 2007–2012
    • East China Normal University
      Shanghai, Shanghai Shi, China
  • 2006–2012
    • The Chinese University of Hong Kong
      • • Department of Surgery
      • • Prince of Wales Hospital
      • • Stanley Ho Center for Emerging Infectious Diseases
      Hong Kong, Hong Kong
    • University of Turku
      Turku, Province of Western Finland, Finland
  • 2002–2012
    • The University of Hong Kong
      • • Department of Chemistry
      • • Department of Microbiology
      Hong Kong, Hong Kong
    • Fuerkang Beijing Institute of Biotechnology
      Peping, Beijing, China
  • 2011
    • Third Military Medical University
      • Institute of Pathology and Southwest Cancer Center
      Ch’ung-ch’ing-shih, Chongqing Shi, China
  • 2004–2006
    • Nanfang Hospital
      Shengcheng, Guangdong, China
    • Qingdao University
      Tsingtao, Shandong Sheng, China