Stable Expression Cell Research Articles

Development and Evaluation of Highly Specific Monoclonal Antibodies against Human LGR5 for the Identification of Colon Cancer Stem Cells

The cancer stem cells is a subpopulation of cancer cells which is responsible for cancer initiation, development and metastasis. Detection and identification of cancer stem cells have been considered as one of the most important objectives for clinical diagnostic and therapeutic purposes. Research evidences indicated that Leucine‐rich repeat containing G‐protein‐coupled receptor 5 (LGR5) is one of the biomarkers specifically expressed on colon cancer stem cells, which is activated by extracellular Wnt molecules to trigger canonical Wnt signaling and gene expression related to cancer development. Therefore, it is critical to develop an LGR5 antibody with great sensitivity and specificity to detect endogenous LGR5 expression in cancer stem cells.In this research, several LGR5 mouse monoclonal antibodies were generated for multiple applications. These LGR5 antibodies are also highly sensitive for flow application on LGR5 stable expression cells and proved to be highly specific with our proprietary high density protein microarray chip assay. Furthermore, we also performed immunohistochemistry assays on colon cancer tissue blocks for diagnostic application. These newly generated LGR5 antibodies could provide new tools for earlier diagnosis and therapeutic guidance on colon cancers.

Experimental study on inhibition effects of the XAF1 gene against lung cancer cell proliferation.

To investigate the effect of high expression of XAF1 in vivo or in vitro on lung cancer cell growth and apoptosis. 1. The A549 human lung cancer cell line was transfected with Ad5/F35 - XAF1, or Ad5/ F35 - Null at the same multiplicity of infection (MOI); (hereinafter referred to as transient transfected cell strain); XAF1 gene mRNA and protein expression was detected by reverse transcription polymerase chain reaction (RT- PCR) and Western blotting respectively. 2. Methyl thiazolyl tetrazolium (MTT) and annexin V-FITC/PI double staining were used to detect cell proliferation and apoptosis before and after infection of Ad5/F35 - XAF1 with Western blotting for apoptosis related proteins, caspase 3, caspase - 8 and PARP. 3. After the XAF1 gene was transfected into lung cancer A549 cells by lentiviral vectors, and selected by screening with Blasticidin, reverse transcription polymerase chain reaction (RT-PCR) and Western blotting were applied to detect mRNA and protein expression, to establish a line with a stable high expression of XAF1 (hereinafter referred to as stable expression cell strain). Twenty nude mice were randomly divided into groups A and B, 10 in each group: A549/ XAF1 stable expression cell strain was subcutaneously injected in group A, and A549/Ctrl stable cell line stable expression cell strain in group B (control group), to observe transplanted tumor growth in nude mice. The mRNA and protein expression of XAF1 in A549 cells transfected by Ad5/F35 - XAF1 was significantly higher than in the control group. XAF1 mediated by adenovirus vector demonstrated a dose dependent inhibition of lung cancer cell proliferation and induction of apoptosis. This was accompanied by cleavage of caspase -3, -8, -9 and PARP, suggesting activation of intrinsic or extrinsic apoptotic pathways. A cell strain of lung cancer highly expressing XAF1 was established, and this demonstrated delayed tumor growth after transplantation in vivo. Adenovirus mediated XAF1 gene expression could inhibit proliferation and induce apoptosis in lung cancer cells in vitro; highly stable expression of XAF1 could also significantly inhibit the growth of transplanted tumors in nude mouse, with no obvious adverse reactions observed. Therefore, the XAF1 gene could become a new target for lung cancer treatment.

Lentivirus vectors construction of SiRNA targeting interference GPC3 gene and its biological effects on liver cancer cell lines Huh-7

ObjectivesTo build GPC3 gene short hairpin interference RNA (shRNA) slow virus vector, observe expression of Huh-7 GPC3 gene in human liver cell line proliferation apoptosis and the effect of GPC3 gene influencing on liver cancer cell growth, and provide theoretical basis for gene therapy of liver cancer. MethodsHepatocellular carcinoma cell line Huh-7 was transfected by a RNA interference technique. GPC3 gene expression in a variety of liver cancer cell lines was detected by fluorescence quantitative PCR. Targeted GPC3 gene sequences of small interfering RNA (siRNA) PGC-shRNA-GPC3 were restructured. Stable expression cell lines of siRNA were screened and established with the help of liposomes (lipofectamineTM2000) as carrier transfection of human liver cell lines. In order to validate siRNA interference efficiency, GPC3 siRNA mRNA expression was detected after transfection by using RT-PCR and Western blot. The absorbance value of the cells of blank group, untransfection group and transfection group, the cell cycle and cell apoptosis were calculated, and effects of GPC3 gene on Huh-7 cell proliferation and apoptosis were observed. ResultsIn the liver cancer cell lines Huh-7, GPC3 gene showed high expression. PGC-shRNA-GPC3 recombinant plasmid was constructed successfully via sequencing validation. Stable recombinant plasmid transfected into liver cancer cell lines Huh-7 can obviously inhibit GPC3 mRNA expression level. ConclusionsThe targeted GPC3 siRNA can effectively inhibit the expression of GPC3.

Anti-PABPC1 co-immunoprecipitation for examining the miRNAs directly targeting the 3'-UTR of EED mRNA.

MicroRNAs (miRNAs) are small, noncoding RNA molecules that regulate post-transcriptional gene expression by base pairing with partially complementary sequences within target messenger RNAs (mRNAs). Although the target genes and the precise biological functions of individual miRNAs remain largely unknown, miRNAs have been implicated in diverse biological processes, including both normal and pathological states. As a single stranded mRNA can be directly targeted by multiple miRNAs, and as the target sites may exist in the 3′-untranslated region (UTR), 5′-UTR, or the coding regions, it is essential to develop an effective method to identify the full-scale miRNA regulatory pattern of each particular gene. In this study, we employed a biochemical approach to identify the miRNA profiles that regulate the expression of embryonic ectoderm development (EED) protein by using anti-PABPC1 ribonucleoprotein (RNP) co-immunoprecipitation (Co-IP). The full length EED mRNA was subcloned into an expression vector and transiently transfected into a Flag-PABPC1 stable expression cell line. Subsequent to cross-linking and an anti-Flag Co-IP, the miRNAs that directly targeted EED were identified. We found that the best time point to distinguish the positive miRNAs from the background was 18 hours after the plasmid transfection. As expected, the miRNAs that directly target EED were found to interact with EED mRNA through the miRNA-induced silencing complex (miRISC). Meanwhile, the EED mRNA was bound by Flag-PABPC1. This method depends on the integrity of the miRISC complex and achieves greater efficiency when ultraviolet irradiation is used for the process of cross-linking. By using anti-PABPC1 RIP, we identified EED to be a new target gene of miR-16; a finding further confirmed using a dual-luciferase assay. In summary, our data indicate that anti-PABPC1 RIP is a validated and direct biochemical method to provide data about specific miRNA-mRNA interactions, as well as global miRNA patterns regulating the mRNAs.

Overexpression of c-Met increases the tumor invasion of human prostate LNCaP cancer cells in vitro and in vivo.

c-Met is a transmembrane tyrosine kinase receptor that may be activated by hepatocyte growth factor, an inducer of epithelial-mesenchymal transition (EMT), to regulate the associated downstream gene expression. This process is critical to cell migration in normal and pathological conditions. In the present study, the function of c-Met in the process of EMT was investigated in prostate cancer. Initially, a c-Met stable expression cell line was constructed using EMT- and c-Met-negative LNCaP prostate cancer cells. Following the identification of c-Met in the transfected cells, the changes in EMT, phosphatidylinositol 3-kinase (PI3K) and extracellular signal-regulated kinase pathway biomarkers were determined by western blot analysis. MTT, soft agar and Transwell assays, and xenograft studies were used to investigate the effects of c-Met on the proliferation, migration and tumorigenicity of LNCaP cells. The results of the present study revealed downregulation of E-cadherin and upregulation of vimentin in LNCaP-Met cells. The results demonstrated that c-Met enhanced proliferation, migration and tumorigenicity capacity when compared with LNCaP and LNCaP-pcDNA3.1 cells. Furthermore, these EMT-like changes were mediated via the PI3K and mitogen-activated protein kinase signaling pathways. The present study clearly demonstrates a crucial function for c-Met in EMT development in prostate cancer. c-Met-targeted treatment may be an effective adjuvant therapy for improving survival rates in patients with prostate cancer.

Meprin Metalloproteases Inactivate Interleukin 6

Meprins have been implicated in the pathogenesis of several inflammatory diseases, including inflammatory bowel disease, in which the cytokine IL-6 is a prominent effector molecule. Because IL-6 levels are elevated markedly in meprin α and α/β knockout mice in an experimental model of inflammatory bowel disease, the interaction between meprins and IL-6 was studied. The results demonstrate that rodent and human meprin A and B cleave IL-6 to a smaller product and, subsequently, are capable of extensive degradation of the cytokine. Analysis of the limited degradation product formed by meprin A indicated that three to five amino acids are removed from the C terminus of the cytokine. Meprin A and meprin B cleaved IL-6 with micromolar affinities (Km of 4.7 and 12.0 μM, respectively) and with high efficiencies (kcat/Km of 0.2 and 2.5 (M(-1)/s(-1)) × 10(6), respectively). These efficiency constants are among the highest for known meprin substrates. Madin-Darby canine kidney cells transiently transfected with meprin α or meprin β constructs also cleave exogenous IL-6. Both human and murine IL-6 cleaved by meprin A or B are inactivated, as demonstrated by their decreased capability to stimulate proliferation of B9 cells. These results are consistent with the proposition that one function of meprin metalloproteases is to modulate inflammation by inactivating IL-6.

<i>p</i>-Synephrine: A Novel Agonist for Neuromedin U2 Receptor

In the brain, Neuromedin U2 receptor (NMU2R) is prominent in the hypothalamic regions and is known to be associated with regulation of several important physiological functions, including food intake, energy balance, stress response, and nociception. In this article, by random screening of compounds using the model of high-throughput screening for NMU2R stable expression, NMU2R negative and NMU2R short hairpin RNA (shRNA) knockdown HEK293 cell lines, for the first time, we discovered that p-synephrine, which is the primary protoalkaloid in Citrus aurantium (bitter orange) and is widely used in weight loss and weight management products, is a highly potent and selective NMU2R agonist. In NMU2R activating ability experiments, p-synephrine was found binding to NMU2R with high efficacy and potency; the efficacy, 50% of the maximum possible effect (EC50) and potency values were determined to be 7.207, 6.604 and 0.227 µmol/L for the NMU2R, respectively. Our researches have important theoretical value for elucidating the mechanisms of p-synephrine in body weight and energy balance regulation. These data provide further evidence for widespread roles for p-synephrine and its receptors in the brain.

Improving Hematopoietic Stem Cell Based Gene Therapy By Targeting CD133+ Cells

IntroductionGenerally, CD34+ cells are used for genetic modification in gene therapy trials. CD34+ cells consist of a heterogeneous cell population with mostly limited long-term repopulating capabilities, resulting in low long-term engraftment levels in particular in those diseases in which gene modified cells lack a proliferative advantage over non-modified cells. Therefore, modifications in gene transfer vectors and gene transfer strategies are required to improve long-term clinical benefit in gene therapy patients. One particular attractive approach to solve this problem is the improvement of HSC based gene transfer by specifically targeting cells with long-term engraftment capabilities. Material and MethodsWe constructed lentiviral gene transfer vectors (LV) specifically targeting CD133+ cells, a cell population with recognized long-term repopulating capabilities. Targeting is achieved by pseudotyping with engineered measles virus (MV) envelope proteins. The MV glycoprotein hemagglutinin, responsible for receptor recognition, is blinded for its native receptors and displays a single-chain antibody specific for CD133 (CD133-LV). These vectors were compared to VSV-pseudotyped lentiviral vectors in in vitro and in vivocompetitive repopulation assays using mobilized peripheral blood CD34+ cells. ResultsSuperior transduction of isolated human hematopoietic stem cell populations (CD34+CD38- or CD34+CD133+ cells) compared to progenitor cell populations (CD34+CD38+ or CD34+CD133-) could be shown using the newly developed CD133-LV. Transduction of total CD34+ cells with CD133-LV vectors resulted in stable gene expression and gene marked cells expanded in vitro, while the number of VSV-G-LV transduced CD34+ cells declined over time. Competitive repopulation experiments in NSG mice showed a significantly improved engraftment of CD133-LV transduced HSCs. At ∼12 weeks post-transplantation gene marked hematopoiesis was dominated by the progeny of CD133-LV transduced cells in 42 out of 52 transplanted animals in the bone marrow and 39 out of 45 transplanted animals in the spleen, respectively. Consistent with this data we could show that stem cell content in the CD133-LV transduced population is about five times higher compared to the VSV-transduced population using a limiting dilution competitive repopulation assay (LDA-CRU). Experiments showing proof of principle for the application of this technology for the correction of Chronic Granulomatous Disease (XCGD) using patient derived CD34+ cells are currently ongoing. DiscussionIn conclusions this new strategy may be promising to achieve improved long-term engraftment in patients treated by gene therapy. Disclosures:No relevant conflicts of interest to declare.

Epidermal Growth Factor (EGF)-induced Corneal Epithelial Wound Healing through Nuclear Factor κB Subtype-regulated CCCTC Binding Factor (CTCF) Activation

Epidermal growth factor (EGF) plays an important role in corneal epithelial migration and proliferation to improve the wound healing process. This study aimed to understand the role of NFκB in EGF-induced corneal epithelial wound healing through regulation of CTCF activity, which plays important roles in cell motility and migration to promote wound healing. The effect of NFκB p50 on corneal epithelial wound healing was investigated by comparing the eyes of wild-type and p50 knockout mice. We found that there was a significant retardation in corneal epithelial wound healing in the corneas of p50 knockout mice. Wound closure rates were measured in human corneal epithelial cells transfected with an NFκB activation-sensitive CTCF expression construct to demonstrate the effect of human CTCF expression under the control of EGF-induced NFκB activation on wound healing. EGF stimulation activated NFκB, which directly triggered the expression of the exogenous human CTCF in transfected cells and, subsequently, promoted human corneal epithelial cell motility, migration, and wound healing. Overexpression of CTCF in corneal epithelial cells and mouse corneas significantly enhanced the wound healing process. Furthermore, the effect of overexpressing NFκB p50 in corneal epithelial cells on the promotion of wound healing was abolished by knockdown of CTCF with CTCF-specific shRNA. Thus, a direct regulatory relationship between EGF-induced NFκB p50 and CTCF activation affecting corneal epithelial wound healing has been established, indicating that CTCF is, indeed, a NFκB p50-targeted and effective gene product in the core transcriptional network downstream from the growth factor-induced NFκB signaling pathway.

An H3K36 Methylation-Engaging Tudor Motif of Polycomb-like Proteins Mediates PRC2 Complex Targeting

Polycomb repressive complex 2 (PRC2) regulates pluripotency, differentiation, and tumorigenesis through catalysis of histone H3 lysine 27 trimethylation (H3K27me3) on chromatin. However, the mechanisms that underlie PRC2 recruitment and spreading on chromatin remain unclear. Here we report that histone H3 lysine 36 trimethylation (H3K36me3) binding activity is harbored in the Tudor motifs of PRC2-associated polycomb-like (PCL) proteins PHF1/PCL1 and PHF19/PCL3. Ectopically expressed PHF1 induced Tudor-dependent stabilization of PRC2 complexes on bulk chromatin and mediated spreading of PRC2 and H3K27me3 into H3K36me3-containing chromatin regions. In murine pluripotent stem cells, we identified coexistence of H3K36me3, H3K27me3, and PHF19/PCL3 at a subset of poised developmental genes and demonstrated that PHF19/PCL3 Tudor function is required for optimal H3K27me3 and repression of these loci. Collectively, our data suggest that PCL recognition of H3K36me3 promotes intrusion of PRC2 complexes into active chromatin regions to promote gene silencing and modulate the chromatin landscape during development.

Abstract A42: Estradiol induced prostaglandin E2 expression to regulate cell proliferation through MAPK/PI3K/COX2 signal pathway in Her2/neu breast cancer cell

Abstract Prostaglandin E2 (PGE2), a product of cyclooxygenase-2 (COX-2) enzymatic activity, induced aromatase activity which converts androgens to estrogens and mediates cell biological function. However, the relationship between estradiol (E2), COX-2 and PGE2 signaling pathway in Her-2/neu breast cancer cell was still unclear. In this report, we elucidate the mechanisms that mediate COX-2 expression and define the relationship of E2 and PGE2 with clinicopathological characteristics in breast cancer patients. The results were presented to demonstrate that the high level of PGE2 (P=0.02) and E2 (P=0.09) was significantly correlated with histological grade. To further investigate the signaling pathways mediating COX-2 gene expression, the experiments were performed in human breast cancer cell lines. In vitro study we found that time and dose courses of COX-2 were induced by E2 treatment in human breast adenocarcinoma cell lines Her-18(Her-2/neu stable expression cell lines), but not in MCF-7 cell lines. Furthermore, the effect was eliminated by pretreatment with MAPK, P38, PI3K, Her-2 inhibitor and estrogen antagonist ICI 182,780. Collectively, our data indicate that MAPK/PI3K/COX-2 is the functional signaling pathway intermediates linking Her-2/neu and E2 and suggest that inhibitors of PGE2 synthesis will suppress cancer cell proliferation in human breast cancer cell lines. Citation Format: Eing-Mei Tsai, Tsung-Hua Hsieh. Estradiol induced prostaglandin E2 expression to regulate cell proliferation through MAPK/PI3K/COX2 signal pathway in Her2/neu breast cancer cell. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr A42.

A Convenient and General Expression Platform for the Production of Secreted Proteins from Human Cells

Recombinant protein expression in bacteria, typically E. coli, has been the most successful strategy for milligram quantity expression of proteins. However, prokaryotic hosts are often not as appropriate for expression of human, viral or eukaryotic proteins due to toxicity of the foreign macromolecule, differences in the protein folding machinery, or due to the lack of particular co- or post-translational modifications in bacteria. Expression systems based on yeast (P. pastoris or S. cerevisiae) (1,2), baculovirus-infected insect (S. frugiperda or T. ni) cells (3), and cell-free in vitro translation systems (2,4) have been successfully used to produce mammalian proteins. Intuitively, the best match is to use a mammalian host to ensure the production of recombinant proteins that contain the proper post-translational modifications. A number of mammalian cell lines (Human Embryonic Kidney (HEK) 293, CV-1 cells in Origin carrying the SV40 larget T-antigen (COS), Chinese Hamster Ovary (CHO), and others) have been successfully utilized to overexpress milligram quantities of a number of human proteins (5-9). However, the advantages of using mammalian cells are often countered by higher costs, requirement of specialized laboratory equipment, lower protein yields, and lengthy times to develop stable expression cell lines. Increasing yield and producing proteins faster, while keeping costs low, are major factors for many academic and commercial laboratories. Here, we describe a time- and cost-efficient, two-part procedure for the expression of secreted human proteins from adherent HEK 293T cells. This system is capable of producing microgram to milligram quantities of functional protein for structural, biophysical and biochemical studies. The first part, multiple constructs of the gene of interest are produced in parallel and transiently transfected into adherent HEK 293T cells in small scale. The detection and analysis of recombinant protein secreted into the cell culture medium is performed by western blot analysis using commercially available antibodies directed against a vector-encoded protein purification tag. Subsequently, suitable constructs for large-scale protein production are transiently transfected using polyethyleneimine (PEI) in 10-layer cell factories. Proteins secreted into litre-volumes of conditioned medium are concentrated into manageable amounts using tangential flow filtration, followed by purification by anti-HA affinity chromatography. The utility of this platform is proven by its ability to express milligram quantities of cytokines, cytokine receptors, cell surface receptors, intrinsic restriction factors, and viral glycoproteins. This method was also successfully used in the structural determination of the trimeric ebolavirus glycoprotein (5,10). In conclusion, this platform offers ease of use, speed and scalability while maximizing protein quality and functionality. Moreover, no additional equipment, other than a standard humidified CO2 incubator, is required. This procedure may be rapidly expanded to systems of greater complexity, such as co-expression of protein complexes, antigens and antibodies, production of virus-like particles for vaccines, or production of adenoviruses or lentiviruses for transduction of difficult cell lines.

Integrin-linked Kinase Functions as a Tumor Promoter in Bladder Transitional Cell Carcinoma

The aim of this study was to elucidate the role of the integrin-linked kinase (ILK) gene in development of human bladder transitional cell carcinoma (BTCC). Expression of ILK protein and ILK mRNA in 56 cases of human BTCC tissue and in 30 cases of adjacent normal bladder tissue was detected by immunohistochemistry S-P and reverse transcription polymerase chain reaction (RT-PCR), respectively. Four specific miRNA RNAi vectors targeting human ILK were synthesized and transfected into BIU-87 cells by liposome to obtain stable expression cell strains. The influence of ILK on proliferation of BTCC was detected by MTT, FCM on athymic mouse tumorigenesis. The positive rate of ILK protein in BTCC tissue (53.6%) was much higher than adjacent normal bladder tissue (10.0%) (p<0.05). Similarly, expression of ILK mRNA in BTCC tissue (0.540 ± 0.083) was significantly higher than in adjacent normal bladder tissue (0.492 ± 0.070) (p<0.05). MTT showed that the proliferation ability of miRNA-ILK transfected group was clearly decreased (p<0.05), the cell cycle being arrested in G0/G1-S, an tumorigenesis in vivo was also significantly reduced (p<0.05). ILK gene transcription and protein expression may be involved in the development of BTCC, so that ILK might be the new marker for early diagnosis and the new target for gene treatment.

Flipase‐mediated cassette exchange in Sf9 insect cells for stable gene expression

Site-specific DNA integration allows predictable heterologous gene expression and circumvents extensive clone screening. Herein, the establishment of a Flipase (Flp)-mediated cassette exchange system in Sf9 insect cells for targeted gene integration is described. A tagging cassette harboring a reporter dsRed gene was randomly introduced into the cell genome after screening different transfection protocols. Single-copy integration clones were then co-transfected with both Flp-containing plasmid and an EGFP-containing targeting cassette. Successful cassette exchange was suggested by emergence of G418-resistant green colonies and confirmed by PCR analysis, showing the absence of the tagging cassette and single integration of the targeting cassette in the same locus. Upon cassette exchange, uniform EGFP expression between clones derived from the same integration site was obtained. Moreover, the resulting cell clones exhibited the expression properties of the parental cell line. EGFP production titers over 40 mg/L were of the same order of magnitude as those achieved through baculovirus infection. This Sf9 master cell line constitutes a versatile and re-usable platform to produce multiple recombinant proteins for fundamental and applied research.

Effect of hypoxia-inducible factor-1α on proliferation and invasion of prostate cancer PC-3 cell in hypoxic situation

Objective WE transfected the recombinant expression plasmid of pcDNA3. 1-HIF-1α into the prostate cancer cells, to research the effect of HIF-1α on proliferation of prostate cancer cell PC-3.Methods We selected a stable expression cell line with G418 were selected by transfection of the recombinant expression plasmid of pcDNA3. 1-HIF-1α into the prostate cancer. The protein and mRNA expression of HIF-1α was assayed by western - blot and RT-PCR. The cells growth curves were described by MTT and the ability of invasion was assayed by Transwell.Results The expression of HIF-1α mRNA was not obviously increased compared to the untransfected prostate cancer cell by RT-PCR, but the expression of HIF-1α protein was up-regulated by western-blot after the recombinant expression plasmid transfected into PC-3. The ability of cell proliferation and invasion was significantly enhanced by MTT and Transwell assays.Conclusion The stable expression cell model of HIF-1α was successfully constructed, which enhanced the proliferation and invasion of prostate cancer cell PC-3. Key words: Hypoxia-inducible factor-1α ; Hypoxic ; Prostate cancer PC-3 ; Proliferation ; Invasion

Hypoxia-inducible factor -1α in prostate cancer: Expression and significance

To study the expression and significance of hypoxia-inducible factor -1 alpha (HIF-1α) in prostate cancer, successfully established recombinant expression plasmids pcDNA3.1-HIF-1α and pll3.7-siHIF-1α were transfected into PC-3 prostate cancer cells using Fermentas transfection reagents. Stable HIF-1α expression cell lines were selected using G418 selective culture. Protein and mRNA expressions of HIF-1α, MMP-2 and MMP-9 were assayed by Western blot and RT-PCR. Cell growth was evaluated using the MTT assay growth curve. The ability of invasion of prostate cancer cells was assayed in Transwell chambers. Compared to other four groups, HIF-1α mRNA expression was not obviously upregulated in pcDNA3.1-HIF-1α-PC-3 cells, while it was obviously downregulated in pll3.7-siHIF-1α-PC-3 cells. MMP-2 and MMP-9 mRNA were significantly upregulated in pcDNA3.1-HIF-1α-PC-3 cells. HIF-1α, MMP-2 and MMP-9 protein were upregulated in pcDNA3.1-HIF-1α-PC-3 cells by Western blot, while they were downregulated in pll3.7-siHIF-1α-PC-3 cells. The abilities of proliferation and invasion of prostate cancer cells were statistically significantly enhanced in pcDNA3.1-HIF-1α-PC-3 cells (Pi€¼0.05). Proliferation and invasion of PC-3 prostate cancer cells are promoted by HIF-1α, which provides a foundation for the research on HIF-1α in the pathogenesis of prostate cancer and suggests that HIF-1α gene may be a good target for anti-tumor therapy. Key words: Hypoxia-inducible factor-1alpha, prostate cancer, expression, significance.

Knockdown of ezrin via RNA interference suppresses Helicobacter pylori-enhanced invasion of gastric cancer cells

Background and Aim: H. pylori interacts with gastric epithelial cells, which may activate signaling pathways important for gastric cancer invasion. Ezrin, a membrane cytoskeletal crosslinker protein, is well documented to regulate cell adhesion and cell motility. The aim of the present study was to determine whether ezrin is involved in H. pylori-induced cancer cell motility and invasion. Methods: The VIL-2 of RNA interference plasmid vector and control plasmid vector were constructed. AGS (a human gastric adenocarcinoma cell line) cells were transfected by these plasmid vectors. The stable expression cell lines AGSezrin was obtained by G418 resistance screening. The express levels of ezrin protein and the cellular invasive potential of four groups, including the AGS control, AGSezrin control, AGS co-culture with H. pylori, AGSezrin co-culture with H. pylori were detected. Meanwhile, the morphology, cell migration and adhesion were determined respectively. Results: Co-culture with H. pylori stimulated AGS cell motility and invasion, up-regulated ezrin expression at the protein level and induced a Hummingbird phenotype. The silencing of ezrin expression suppressed the motility and invasion of gastric cancer cells and inversed the cell invasion phenotype and enhanced the ability for cell adhesion. Conclusion: Knockdown of ezrin by RNAi suppresses H. pylori-enhanced migration and invasion of gastric cancer cells. These findings indicate that ezrin may play a key role in the migration and invasion of gastric cancer cells, and thus may be a therapeutic target to prevent metastasis of gastric cancer promoted by H. pylori infection.

Mutant HFE H63D Protein Is Associated with Prolonged Endoplasmic Reticulum Stress and Increased Neuronal Vulnerability

A specific polymorphism in the hemochromatosis (HFE) gene, H63D, is over-represented in neurodegenerative disorders such as amyotrophic lateral sclerosis and Alzheimer disease. Mutations of HFE are best known as being associated with cellular iron overload, but the mechanism by which HFE H63D might increase the risk of neuron degeneration is unclear. Here, using an inducible expression cell model developed from a human neuronal cell line SH-SY5Y, we reported that the presence of the HFE H63D protein activated the unfolded protein response (UPR). This response was followed by a persistent endoplasmic reticulum (ER) stress, as the signals of UPR sensors attenuated and followed by up-regulation of caspase-3 cleavage and activity. Our in vitro findings were recapitulated in a transgenic mouse model carrying Hfe H67D, the mouse equivalent of the human H63D mutation. In this model, UPR activation was detected in the lumbar spinal cord at 6 months then declined at 12 months in association with increased caspase-3 cleavage. Moreover, upon the prolonged ER stress, the number of cells expressing HFE H63D in early apoptosis was increased moderately. Cell proliferation was decreased without increased cell death. Additionally, despite increased iron level in cells carrying HFE H63D, it appeared that ER stress was not responsive to the change of cellular iron status. Overall, our studies indicate that the HFE H63D mutant protein is associated with prolonged ER stress and chronically increased neuronal vulnerability.

Study on a putative, proprotein convertase-cleaved product of HBV core protein in vitro

To investigate the cleavage of HBV core protein in vivo by proprotein convertase furin or its family members and observe the intracellular localization of the putative cleaved product. Recombinant HBV core protein was incubated with furin under different conditions in vitro, and the reaction was checked with Western blotting. The recombinant vectors expressed the putative cleaved fragment and intact core protein (serves as control) were constructed. The stable expression cell lines were established by transfecting constructs into HepG2 cell line, for which indirect immunofluorescence staining was used by monoclonal anti-HBc against the region shared by core protein and its cleaved product .The confocal microscopy was carried out to observe the intracellular distribution. HBV core protein was cleaved by furin in vitro under different tested conditions. The molecular weight of the major cleaved product just about 15,000 was in concordance with the expectation. The expressed cleaved fragment could react to the monoclonal antibody against core protein, and mainly located in cytosol in particle style just like the intact core protein. HBV core protein can be cleaved by furin in vitro. The major cleaved product has similar antigenicity and subcellular distribution to core protein. These data suggest that proprotein convertase furin or its family members play important roles in HBV replication regulation, and the cleaved product may be involved in antiviral immunity of HBV infection. Further investigations are imperative.

Effect of autophagy on paclitaxel-induced CaSki cell death.

To observe the effect of autophagy on paclitaxel-induced CaSki cell death through the regulation of the expression of autophagy gene Beclin1, and to explore the interaction and relationship between autophagy and apoptosis. Eukaryotic expression vector pcDNA3.1-Beclin1 and RNA interference vector pSUPER-Beclin1 were transfected into human cervical cancer CaSki cells in vitro and screened for stable expression cell lines. The formation of autophagic vacuoles was observed with an electronic microscope. The expression of Beclin1 and LC3 was measured by Western blot. After being treated with paclitaxel, the change of cell proliferation was assessed by MTT assay, the percentage of apoptotic cells and autophagic cells were analyzed by flow cytometry. A lot of autophagic vacuoles were observed in pcDNA3.1-Beclin1 cells by electronic microscopy. Beclin1 and LC3 protein expression was up-regulated in CaSki cells transfected with pcDNA3.1-Beclin1, and was inhibited in cells transfected with pSUPER-Beclin1. MTT assay revealed the survival rate of CaSki cells was significantly decreased after being transfected with pcDNA3.1-Beclin1. After being treated with paclitaxel, the percentages of apoptotic cells and autophagic cells were both increased in pcDNA3.1-Beclin1 group compared with that of the blank control group especially the increase of apoptosis was particularly evident. Autophagy and apoptosis have different roles in the process of paclitaxel-induced cervical cancer CaSki cell line death. Overexpression of Beclin1 in CaSki cells may enhance the apoptosis induced by paclitaxel.