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Xiao-Ling Li

Publications and source records attributed to Xiao-Ling Li.

At least 19 recordsLinked to original sources
PubMed2006

Gene expression profiling of nasopharyngeal carcinoma reveals the abnormally regulated Wnt signaling pathway.

Nasopharyngeal carcinoma (NPC) is a particularly common malignant disease in areas of south China and Southeast Asia. To characterize the gene expression profiling of NPC, we detected the gene expression profiles in 22 NPC and 10 nontumor nasopharyngeal epithelial tissues by complementary DNA microarray. We identified 503 genes that were significantly (P < .001) differentially regulated between NPC and nontumor nasopharyngeal epithelial tissues. The differentially expressed genes are involved in many signaling pathways, such as the Wnt, transforming growth factor-beta, and mitogen-activated protein kinase signaling pathways. The aberrant expression of the Wnt signaling pathway components, such as wingless-type MMTV integration site family, member 5A, Frizzled homolog 7, casein kinase IIbeta, beta-catenin, CREB-binding protein, and Dishevelled-associated activator of morphogenesis 2 was validated on the NPC tissue microarrays. The data suggest that the Wnt signaling pathway may be abnormally regulated in NPC, which provides insight into the molecular mechanisms of NPC.

Adolescent↗
PubMed2006

BRD2 is one of BRD7-interacting proteins and its over-expression could initiate apoptosis.

BRD7 is a potential nuclear transcription regulation factor related to nasopharyngeal carcinoma (NPC). BRD2, a putative BRD7-interacting protein, has been screened from human fetal brain cDNA library by yeast two-hybrid system. This study was to further identify the interaction between BRD7 and BRD2 in mammalian cells, and to investigate the subcellular localization of BRD2, as well as the effect on the functions of cell biology. Both immunoprecipitation and subcellular colocalization were performed together to identify the interaction of BRD7 with full-length BRD2, as well as C-terminal truncated BRD2 or N-terminal truncated BRD2. GFP direct fluorescence and Hochest 33258 staining were used to investigate the cellular localization pattern of BRD2 and the roles in initiating cell apoptosis in COS7 and HNE1. The results showed that BRD7 could interact with BRD2 and the region from amino acid 430 to 798 of BRD2 was critical for the interaction of BRD2 with BRD7. BRD2 mainly localizes in nucleus in two distribution patterns, diffused and dotted, and BRD2 has distinct roles in initiating apoptosis, and the dotted distribution pattern of BRD2 in nucleus may be a morphologic marker of cell apoptosis.

Animals↗
PubMed2006

Differential expression of Epstein-Barr virus-encoded RNA and several tumor-related genes in various types of nasopharyngeal epithelial lesions and nasopharyngeal carcinoma using tissue microarray analysis.

Studies have revealed that Epstein-Barr virus (EBV) infection, genetic aberration, and environmental factors are of importance in the development of nasopharyngeal carcinoma (NPC), although the definite mechanism remains to be fully elucidated. The aim of our study is to investigate using tissue microarray analysis whether differential expression of EBV-encoded small RNA-1 (EBER-1) and several tumor-related genes were associated with NPC carcinogenesis. Immunohistochemistry and in situ hybridization were performed on tissue microarrays containing 148 NPCs and 164 noncancerous nasopharyngeal epithelia (NPE) with different morphologic features. We found that overexpressions of EBER-1 hybridization signals, p53, p21ras, and bcl-2 proteins and loss expressions of p16 and p27 proteins were significantly increased in NPC tissues compared with normal NPE and hyperplastic NPE (P </= .001). The overexpressions of EBER-1 and p53 (P < .001) and the loss expressions of P16 (P < .001) and P27 (P = .005) were also significantly higher and more frequently observed in NPC than in dysplastic NPE. The positive expression of EBER-1 hybridization signals in NPC had significant associations with overexpressions of p53 (P < .001), p21ras (P = .041), and bcl-2 proteins (P < .001) and loss expression of p16 protein (P = .001). Further analysis confirmed that the abnormal expression of p53, p16, and p27 proteins occurred in the earliest stage of nasopharyngeal epithelial carcinogenesis. In the final logistic regression analysis model, the positive hybridization signals of EBER-1 and the abnormal expression of p53, p16, and p27 proteins were independent contributions for nasopharyngeal carcinogenesis, and EBER-1 was the most significant, independent predictor of nasopharyngeal carcinogenesis (hazard ratio = 13.412, 95% confidence interval 6.179-29.111, P < .001). In conclusion, EBV infection, together with overexpressions of p53, and loss expressions of p16 and p27 proteins are involved in the multistep process of human nasopharyngeal epithelial carcinogenesis.

Adenocarcinoma↗
PubMed2006

[Advances in high-density whole genome-wide single nucleotide polymorphism array in cancer research].

A single nucleotide polymorphism (SNP) is the most common type of genetic variation, and millions of SNPs have been documented so far. Because of dense distribution of SNPs across the genome, SNPs are viewed as ideal markers for research use in the post-genomic era. The application of the high-density whole genome-wide SNP array not only leads to more rapid, economical, and high throughput genotyping but also makes the investigation of the genetic variety or change in global patterns possible. The SNP array will be widely used in various research fields, such as large-scale genome-wide linkage and association studies to discover susceptibility genes in cancer, and loss of heterozygosity analysis to discover tumor suppressor genes and tumor molecular markers, and so on.

Genetic Predisposition to Disease↗
PubMed2005

Intracellular co-localization of SPLUNC1 protein with nanobacteria in nasopharyngeal carcinoma epithelia HNE1 cells depended on the bactericidal permeability increasing protein domain.

Epithelial surfaces constitute natural immunobarriers against environmental threats. These barriers are brimming with fluids that bind, transport, cleave or degrade bacterial cells and their endotoxic by-products. Saliva and the airway surface-lining fluid (ASL) comprise the important fluid constituents. Short palate, lung and nasal epithelium clone 1 (SPLUNC1) is a potential host defensive protein that is secreted from the submucosal gland to the saliva and nasal lavage fluid. However, its antimicrobial spectrum and antimicrobial mechanism is not clear. Through green fluorescence protein (GFP) mediated subcellular localization experiments in nasopharyngeal carcinoma (NPC) HNE1 cell line, we determined that the intracellular GFP-tagged SPLUNC1 protein binds to a miniscule microorganisms, approximately 50-400nm in size, after the bactericidal permeability increasing protein (BPI) domain was deleted, GFP-tagged truncated SPLUNC1 protein lost its function of binding to the miniscule microorganisms. We verified that these microorganisms are nanobacteria (NB) with a negative staining using transmitted electronic microscope (TEM) and immunofluorescent analysis using an NB-specific antibody. We isolated and cultured the NB from the cultured nasopharyngeal carcinoma epithelia HNE1 cell supernatant. We found that the NB did not absorb the Hoechst stain, even when we extended the staining time to 35min. However, with the time extension the larger sized NB (larger than 300nm) did stain positively. From the biopsy specimen of NPC, we also detected the NB, which can lead to the swelling of mitochondria in the infected host cells. We hypothesize that SPLUNC1 and NB co-localization is due to the GFP-tagged SPLUNC1 protein binding to the lipopolysaccharide (LPS) of the Gram-negative NB, which can play an important role in the host defense of nasopharyngeal epithelium. This research sheds new light on the mechanism of SPLUNC1 involvement in the host upper respiratory tract defense system.

Antimicrobial Cationic Peptides↗
PubMed2005

Tissue distribution of the secretory protein, SPLUNC1, in the human fetus.

We previously identified a tissue-specific gene, short palate, lung, and nasal epithelium clone 1 (SPLUNC1), in nasopharyngeal epithelial tissues. SPLUNC1 was differentially expressed in nasopharyngeal carcinoma. Bioinformatic analysis revealed that SPLUNC1 has the bactericidal permeability-increasing protein/lipid-binding protein (BPI/LBP) domain and a 19 amino acid signal peptide, which suggest that it is a secretory protein. Its precise cellular localization in the respiratory tract is mainly in mucous cells and ducts of submucosal glands. However, little is known about its expression pattern in various human tissues. We generated a highly specific antibody and analyzed its distribution in the human fetus by immunohistochemistry to more precisely determine SPLUNC1 protein localization in human tissues. The results were further validated by RT-PCR. Our results showed that SPLUNC1 protein is expressed at not only the serous glands and epithelium of the upper respiratory tract and digestive tract, but also in the oculi of human embryos. Interestingly, we also found positive staining in fetus adipose tissue, a result not previously reported in studies of adult human tissues. Western blot analysis detected a 24 kDa SPLUNC1 protein in the compounds of nasopharyngeal secretions. This secretory protein was also detected in saliva and tears. Our research suggests that SPLUNC1 protein may not only be an antimicrobial peptide that plays an important role in the maintenance of homeostasis in the upper respiratory tract, oculi, and alimentary tract, it may also be important in the development and lipid metabolism of the adipose tissue.

Adipose Tissue↗
PubMed2005

Study of a novel brain relatively specific gene LRRC4 involved in glioma tumorigenesis suppression using the Tet-on system.

LRRC4 is a novel relatively specific gene, which displays significant down-regulation in primary brain tumor biopsies and has the potential to suppress brain tumor growth. In this study, we investigated the growth inhibitory effect of LRRC4 on tumorigencity in vivo and on cell proliferation in vitro by a tetracycline-inducible expression system. Results showed that LRRC4 significantly reduced the growth and malignant grade of xenografts arising from glioblastoma U251MG cells. Cell proliferation was markedly inhibited after U251MG Tet-on-LRRC4 cell induction with doxycycline. Flow cytometry and Western blot analysis demonstrated that LRRC4 mediated a delay of the cell cycle in late G1, possibly through up-regulating the expressions of p21Waf1/cip1 and p27Kip1 and down-regulating the expressions of cyclin-dependent kinase 2, retinoblastoma protein and epidermal growth factor receptors. Together, these findings provide clues to the function of LRRC4 as a negative regulator of cell growth and underscore a link between the above-mentioned cyclins, cyclin-associated molecules and tumorigenicity.

Animals↗
PubMed2005

Profiling of differentially expressed genes in LRRC4 overexpressed glioblastoma cells by cDNA array.

Our previous study has shown that LRRC4 is a novel member of the leucine-rich repeat (LRR) superfamily and has the potential to suppress brain tumor growth. In order to further analyze the functions of LRRC4 on the maintenance of normal function and suppression of tumorigenesis in the central nervous system, we investigated alterations in gene expression related to neurobiology by the Atlas array in two inducible dual-stable LRRC4-overexpressing cell lines. Seventeen of 588 genes spotted on the Atlas membrane showed altered expression levels in LRRC4 transfected U251MG Tet-on cells, which are involved in cell proliferation and cell cycle progression, tumor invasion and metastasis, and neurotransmitter synthesis and release. In addition, cell invasion assay results showed that LRRC4 can inhibit the U251MG cell migration. These studies represent the first cDNA array analysis of the effects of LRRC4 on the involvement of different neurobiological genes in U251MG glioblastoma cells and provide new insights into the function of LRRC4 in glioma.

Blotting, Western↗
PubMed2004

RNase-L regulates the stability of mitochondrial DNA-encoded mRNAs in mouse embryo fibroblasts.

Accelerated decrease in the levels of mitochondrial DNA-encoded mRNA (mt-mRNA) occurs in neuronal cells exposed either to the excitatory amino acid, glutamate or to the sodium ionophore, monensin, suggesting a role of mitochondrial RNase(s) on the stability of mt-mRNAs. Here we report that in mouse embryo fibroblasts that are devoid of the interferon-regulated RNase, RNase-L, the monensin-induced decrease in the half-life of mt-mRNA was reduced. In monensin (250 nM)-treated RNase-L(+/+) cells the average half-life of mt-mRNA, determined after termination of transcription with actinomycin D, was found to be 3h, whereas in monensin-treated RNase-L(-/-) cells the half-life of mt-mRNA was >6h. In contrast, the stability of nuclear DNA-encoded beta-actin mRNA was unaffected. Induction of RNase-L expression in mouse 3T3 fibroblasts further decreased the monensin-induced reduction in mt-mRNA half-life to 1.5h. The results indicate that the RNase-L-dependent decrease in mtDNA-encoded mRNA transcript levels occurs through a decrease in the half-life of mt-mRNA, and that RNase-L may play a role in the stability of mt-mRNA.

3T3 Cells↗
PubMed2004

BRD7, a novel bromodomain gene, inhibits G1-S progression by transcriptionally regulating some important molecules involved in ras/MEK/ERK and Rb/E2F pathways.

Bromodomain is a 110 amino acid domain. It is evolutionally conserved and is found in proteins strongly implicated in signal-dependent transcriptional regulation. BRD7 is a novel bromodomain gene and it is downexpressed in nasopharyngeal carcinoma (NPC) biopsies and cell lines; its function is poorly understood. In the present study, tet-on inducible expression system was used to investigate the role of BRD7 in cell growth and cell cycle progression. We found that ectopic expression of BRD7 in NPC cells inhibited cell growth and cell cycle progression from G1 to S. We further performed cell cycle cDNA array to screen potential transcriptional targets of BRD7 in cell cycle. Thirteen important signaling molecules, mainly implicated in ras/MEK/ERK and Rb/E2F pathways, were differentially expressed by induction of BRD7. Moreover, we observed that BRD7 could regulate the promoter activity of E2F3, one of its targets. Taken together, the present study indicated that BRD7 inhibited G1-S progression by transcriptionally regulating some important molecules involved in ras/MEK/ERK and Rb/E2F pathways and suggested that BRD7 may present a promising candidate of NPC trade mark associated tumor suppressor gene.

Blotting, Western↗
PubMed2004

Poly(L-lysine)-modified silica nanoparticles for the delivery of antisense oligonucleotides.

Silica nanoparticles were prepared in a microemulsion system, using polyoxyethylene nonylphenyl ether/cyclohexane/ammonium hydroxide. The surface charge of the particle was modified with PLL [poly(L-lysine)]. PAGE demonstrated the ability of PMS-NP (PLL-modified silica nanoparticles) to bind and protect antisense ODNs (oligonucleotides). The intracellular localization of FITC-labelled ODN was investigated by fluorescence microscopy. The results demonstrated that ODN could be delivered to cytoplasm. Flow-cytometry analysis showed a 20-fold enhancement of ODN delivered by PMS-NP compared with free ODN for a serum-free medium. Blocking efficacy of c- myc antisense ODN, delivered by PMS-NP, was examined in HNE1 and HeLa cell lines. Significant down-regulation of c- myc mRNA levels was observed in both the cell lines. However, the cellular uptake efficiency and antisense effects on target gene decreased in the presence of serum-containing medium. The analysis of the filtration assay showed that PMS-NP interacted with serum proteins. These results indicated that PMS-NP was a suitable delivery vector for antisense ODN, although its delivery efficiency decreased in the presence of a serum-containing medium.

Carcinoma↗
PubMed2004

mitochondrial ceramidase overexpression up-regulates Bcl-2 protein level in K562 cells, probably through its metabolite sphingosine-1-phosphate.

Recently, a mitochondrial ceramidase has been identified and cloned, whose mitochondrial localization strongly suggests the existence of an unexpected mitochondrial pathway of ceramide metabolism that may play a key role in mitochondrial functions, especially in the regulation of apoptosis. To explore the biological effect of mitochondrial ceramidase on cells, pcDNA 3.1/His-CDase plasmid, containing mitochondrial ceramidase cDNA sequence, was transducted into K562 cells mediated by liposome, and G418 was used to screen for positive colonies. A stable transfected K562 cell line was established and named as 'K562TC'. The difference between K562 and K562TC cells in chemotheraputic cytotoxicity response and serum-withdrawal resistance and Bcl-2 protein expression were evaluated by MTT assay, annexin V/PI test, flow cytometry or Western blotting, respectively. The results showed that although survival was comparable between K562 and K562TC cells after exposed to adriamycin, etoposide or arsenious acid, K562TC cells with elevated Bcl-2 protein expression level as identified by FCM or Western blotting revealed stronger resistance to apoptosis induced by serum withdrawal than their parental cells. Inhibition of mitochondrial ceramidase expression in K562TC cells by its specific antisense oligodeoxynucleotide was correlated with a decrease in Bcl-2 protein level. N, N-dimethylsphingosine, a sphingosine kinase inhibitor, depleted intracellular sphingosine-1-phosphate production, also abrogated Bcl-2 protein expression in K562TC cells, while Bcl-2 protein level in K562 cells was up-regulated by exogenous sphingosine-1-phosphate. It is concluded that mitochondrial ceramidase overexpression in K562 cells leads to markedly elevated level of Bcl-2 protein and results in more resistance to serum withdrawal. This effect is initiated not by sphingosine, the direct metabolite of mitochondrial ceramidase, but via sphingosine-1-phosphate, its phosphorylated form. This is the first evidence that mitochondrial ceramidase, through its sphingoid metabolite sphingosine-1-phosphate, up-regulates Bcl-2 protein expression in K562 cells.

Amidohydrolases↗
PubMed2003

IONP-PLL: a novel non-viral vector for efficient gene delivery.

BACKGROUND: Non-viral methods of gene delivery have been an attractive alternative to virus-based gene therapy. However, the vectors that are currently available have drawbacks limiting their therapeutic application. METHODS: We have developed a self-assembled non-viral gene carrier, poly-L-lysine modified iron oxide nanoparticles (IONP-PLL), which is formed by modifying poly-L-lysine to the surface of iron oxide nanoparticles. The ability of IONP-PLL to bind DNA was determined by ratio-dependent retardation of DNA in the agarose gel and co-sedimentation assay. In vitro cytotoxic effects were quantified by MTT assay. The transfection efficiency in vitro was evaluated by delivering exogenous DNA to different cell lines using IONP-PLL. Intravenous injection of IONP-PLL/DNA complexes into mice was evaluated as a gene delivery system for gene therapy. The PGL2-control gene encoding firefly luciferase and the EGFP-C2 gene encoding green fluorescent protein were used as marker genes. RESULTS: IONP-PLL could bind and protect DNA. In contrast to PLL and cationic liposomes, IONP-PLL described here was less cytotoxic in a broad range of concentrations. In the current study, we have demonstrated that IONP-PLL can deliver exogenous gene to cells in vitro and in vivo. After intravenous injection, IONP-PLL transferred reporter gene EGFP-C2 to lung, brain, spleen and kidney. Furthermore, we have demonstrated that IONP-PLL transferred exogenous DNA across the blood-brain barrier to the glial cells and neuron of brain. CONCLUSIONS: IONP-PLL, a low-toxicity vector, appears to have potential for fundamental research and genetic therapy in vitro and in vivo, especially for gene therapy of CNS disease.

Animals↗
PubMed2003

[Expression of BRD7-interacting proteins,BRD2 and BRD3, in nasopharyngeal carcinoma tissues].

BACKGROUND & OBJECTIVE: BRD7 is a novel gene tightly associated with nasopharyngeal carcinoma(NPC) cloned by cDNA representational difference analysis (cDNA RDA). Two proteins,BRD2 and BRD3, including bromodomain and interacting with BRD7 protein had been screened from human fetal brain cDNA library by yeast two-hybrid system. This study was designed to further identify the interactions of BRD2 and BRD3 with BRD7 respectively and to investigate the expression and action pattern of BRD2 and BRD3 in NPC. METHODS: BRD2 and BRD3 genes were respectively co-transformed to yeast Y187 with BRD7 gene, then the yeast cotransformers were blotted to nylon membrane. And then the expression of report gene Lac Z by beta-Gal was determined and the interactions of BRD2 and BRD3 proteins with BRD7 protein were identified. Besides,reverse transcription-polymerase chain reaction (RT- PCR) was used to examine the expression of BRD2 and BRD3 genes in normal nasopharyngeal epithelium and NPC biopsies, and to detect the effect of re-expression of BRD7 gene on the expression of BRD2 and BRD3 genes in HNE1 stably transfected BRD7 gene. RESULTS: The yeast transformers showed all blue by yeast two-hybrid system, which further identified that BRD2 and BRD3 proteins could respectively interact with BRD7 protein. Down-expression or loss of BRD2 and BRD3 genes were detectable in NPC biopsies. The expression levels of BRD2 and BRD3 were increasing with the re-expression of BRD7 gene in HNE1 stably transfected with BRD7. CONCLUSION: BRD7 protein could respectively interact with proteins, BRD2 and BRD3, and BRD7 could up-regulate the expression levels of BRD2 and BRD3 genes in mRNA level to some extent. Each of these three homolog proteins might be capable of forming heteromers with the others, which play important roles in the suppression of growth of NPC cells.

Chromosomal Proteins, Non-Histone↗
PubMed2003

[Expression of a new cloned nitroreductase gene NOR1 and purification of expressed product].

BACKGROUND & OBJECTIVE: NOR(1)is a good candidate of tumor suppressor/susceptibility gene associated with nasopharyngeal carcinoma. This study was designed to construct the prokaryotic expression vector and to investigate the expression of nitroreductase gene NOR(1)in Escherichia coli and to purify expressed product. METHODS: Total RNA was subtracted from normal nasopharyngeal carcinoma tissue. The full length of NOR(1)gene was amplified by reverse transcription-polymerase chain reaction (RT-PCR) and digested with BamHIand XhoI restriction endonucleases. The plasmid pGEX-4T-2 was also digested with BamHI and XhoI,then the NOR(1)gene was inserted into vector pGEX-4T-2. The recombinant expression vector pGEX-4T-2/NOR(1)was identified by sequencing and digested with restriction enzymes. E.coli Jm105 transformed with the recombinant plasmid was induced by IPTG to express GST fusion protein. The result was confirmed by Western blot analysis and the purified targeted protein was obtained by affinity chromatography. RESULTS: The 1.25kb NOR(1)gene was successfully isolated. After induction, a new anticipated protein of 74 kDa appeared on sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE). It existed not only in supernatant but also in precipitation of broken bacteria. The result was confirmed by Western blot analysis,and the purified targeted protein was obtained by affinity chromatography. CONCLUSION: The successes in construction of expression vector of NOR(1), expression and purification of GST/NOR(1)fusion protein make it possible to prepare for the polyantibodies for NOR(1).

Cloning, Molecular↗
PubMed2003

[Analysis of splicing variants in NASG 3'UTR, down-regulated in nasopharyngeal carcinoma, and its expression in multiple cancer tissues].

BACKGROUND & OBJECTIVE: NASG gene, a tissue-specific gene of human nasopharyngeal epithelium was isolated by suppression subtractive hybridization. This study was designed to analyze splicing variants in NASG 3'untranslated region (UTR) and its expression profiling in multiple cancer tissues. METHODS: The PCR primers were designed in NASG 3'UTR around the splicing variants and reverse transcription-polymerase chain reaction (RT-PCR) was performed. The PCR products were separated and sequenced. The expression patterns of NASG were detected by RT-PCR among nasopharyngeal carcinoma (NPC) cell line HNE1, primary human embryo nasopharyngeal epithelial cells, NPC biopsies, and normal adult nasopharyngeal epithelial tissues. Its expression profiling in multiple cancer tissues were tested by cancer profiling array hybridization. RESULTS: There were three splicing variants in NASG 3'UTR. NASG was identified to be down-regulated in NPC cell line HNE1 and 71% of the NPC biopsies, but up-regulated in 25% lung of the cancer biopsies, and not express in other cancer tissues and normal tissues. CONCLUSION: There were three splicing variants in NASG 3'UTR. Its abnormal expression may be an important molecular event in NPC and lung cancer.

3' Untranslated Regions↗