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ABSTRACT: The aim of this study was to characterize the molecular mechanism of preeclampsia (PE) development through miR-155.
PE and normal placentas were used to measure miR-155 and cysteine-rich protein 61 (CYR61) expression. CYR61 3' untranslated region was validated as the target of miR-155 using in vitro transfections. miR-155 and CYR61 expression levels were assessed by real-time reverse transcription polymerase chain reaction or Western blot.
An inverse correlation was found between miR-155 and CYR61 expression levels, with miR-155 up-regulated and CYR61 down-regulated in PE tissues. Luciferase assays and CYR61 transfection assays experimentally validated that miR-155 efficiently targets the 3' untranslated region of CYR61.
This study reported for the first time that overexpression of miR-155 contributes to PE development by targeting and down-regulating angiogenic regulating factor CYR61, leading to pathological alterations. This finding not only characterizes a new mechanism for the disease but also provides a potential therapeutic target.
American journal of obstetrics and gynecology 05/2010; 202(5):466.e1-7. · 3.28 Impact Factor
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ABSTRACT: Antisense RNA is the first noncoding RNA found to have a regulatory function. With the advances of biological science, it has been recognized that the function of antisense RNAs is not only limited to post-transcriptional regulation, but extends to transcriptional regulation of various important genes leading to epigenetic changes in DNA methylation and histone modifications. Gene regulation by antisense RNA is a general phenomenon observed in eukaryotic cells while genome-wide natural antisense transcripts have been identified in many animals and plants. Antisense RNAs are not only involved in X-chromosome inactivation and imprinted silencing in normal cells, but aberrantly expressed antisense RNAs can also induce epigenetic silencing of tumor suppressor genes in cancer cells and deletion-induced aberrant antisense RNAs lead to epigenetic silencing and diseases. While a general picture of the pathways involved in antisense RNA-mediated gene regulation has emerged, many questions remain. The mechanisms by which genes are regulated by antisense RNAs, antisense transcript itself is produced and aberrant antisense RNAs induce human diseases are all research focuses of the future.
Epigenomics 02/2010; 2(1):139-50.
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ABSTRACT: To evaluate loss of imprinting (LOI) and expression of the IGF2 gene in matched esophageal normal and adenocarcinoma tissues, we studied a prospective cohort of 77 patients who underwent esophageal resection between 1998 and 2003. IGF2 imprinting status was determined by reverse transcription-polymerase chain reaction (PCR) following ApaI digestion, and quantitative PCR was used to evaluate IGF2 expression, which was correlated with clinicopathologic findings, disease-free and overall survival. In total, 32% (14/44) of informative tissues showed loss of IGF2 imprinting, with a strong correlation between the tumor and normal esophageal epithelia (Kappa = 0.89, P < 0.01). Normal epithelia with LOI had increased expression of IGF2 [median: 2.91, 95% confidence interval (CI): 0.93-5.06] compared with imprinted normal epithelia (median: 1.13, 95% CI: 0.85-1.39) (P = 0.03). In contrast, tumors with LOI had significantly reduced IGF2 expression (median: 1.87, 95% CI: 0.53-5.21) compared with normally imprinted tumors (median: 6.79, 95% CI: 3.39-15.89) (P = 0.016). Patients below the age of 65 years with normally imprinted tumors had significantly reduced 5 year disease-free survival (DFS) (24%) compared with patients whose tumors had LOI for IGF2 (55%) (P = 0.03). Cox regression analysis showed that IGF2 overexpression was associated with significantly reduced disease-free survival (P = 0.04). We conclude that in a subgroup of younger patients, loss of IGF2 imprinting was associated with improved outcome following esophageal resection. Expression of IGF2 in esophageal adenocarcinoma and normal esophageal epithelia depended on imprinting status and tissue type, suggesting novel molecular regulatory mechanisms in esophageal tumorigenesis.
Carcinogenesis 10/2009; 30(12):2117-22. · 5.70 Impact Factor
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Marcia Cruz-Correa,
Ronghua Zhao,
Myriam Oviedo,
Raul D Bernabe,
Mercedes Lacourt,
Alberto Cardona,
Reynold Lopez-Enriquez,
Steven Wexner,
Carmen Cuffari,
Linda Hylind,
Elizabeth Platz, Hengmi Cui,
Andrew P Feinberg,
Francis M Giardiello
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ABSTRACT: Loss of genomic imprinting (LOI) of the insulin-like growth factor-2 gene (IGF2) is an epigenetic change involving abnormal activation of the normally silent maternally inherited allele. LOI of IGF2 gene is found in tumor tissue, normal adjoining mucosa and peripheral blood lymphocytes (PBL) of some patients with colorectal cancer (CRC), suggesting that this alteration precedes and is a risk factor for CRC. However, whether LOI of IGF2 is transitory or remains a permanent epigenetic alteration is unknown.
Four-hundred patients, mean age 60.7 years (range 15-95), 287 (80%) Caucasian were studied. This included 210 (51.4%) patients with no colorectal neoplasia, and 190 (48.6) with colorectal neoplasia. LOI of IGF2 was present in all age strata examined, and no statistically significant association across age strata (p trend > 0.05) was noted. Forty-nine patients had repeat analysis of blood imprinting status at a mean follow up time of 38.2 +/- 12.9 months. All but three patients had the same imprinting status at follow up (94% agreement, kappa 0.79, p < 0.001). Genomic imprinting was stable for patients with and without colorectal neoplasia.
Standard RT-PCR assays for imprinting analysis of IGF2 were performed on PBL from ApaI informative individuals recruited at baseline and repeated 1 to 3 years later. Prevalence of LOI of IGF2 was also evaluated according to age strata.
LOI of the IGF2 gene in PBL appears to be a stable epigenetic phenomenon in most patients. Furthermore, LOI of IGF2 was not associated with age, suggesting an inherited or congenital epigenetic event. These findings support the concept that LOI of IGF2 may be a useful risk factor for CRC predisposition.
Epigenetics: official journal of the DNA Methylation Society 03/2009; 4(2):114-8. · 4.58 Impact Factor
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Rafael A Irizarry,
Christine Ladd-Acosta,
Bo Wen,
Zhijin Wu,
Carolina Montano,
Patrick Onyango, Hengmi Cui,
Kevin Gabo,
Michael Rongione,
Maree Webster,
Hong Ji,
James B Potash,
Sarven Sabunciyan,
Andrew P Feinberg
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ABSTRACT: For the past 25 years, it has been known that alterations in DNA methylation (DNAm) occur in cancer, including hypomethylation of oncogenes and hypermethylation of tumor suppressor genes. However, most studies of cancer methylation have assumed that functionally important DNAm will occur in promoters, and that most DNAm changes in cancer occur in CpG islands. Here we show that most methylation alterations in colon cancer occur not in promoters, and also not in CpG islands, but in sequences up to 2 kb distant, which we term 'CpG island shores'. CpG island shore methylation was strongly related to gene expression, and it was highly conserved in mouse, discriminating tissue types regardless of species of origin. There was a notable overlap (45-65%) of the locations of colon cancer-related methylation changes with those that distinguished normal tissues, with hypermethylation enriched closer to the associated CpG islands, and hypomethylation enriched further from the associated CpG island and resembling that of noncolon normal tissues. Thus, methylation changes in cancer are at sites that vary normally in tissue differentiation, consistent with the epigenetic progenitor model of cancer, which proposes that epigenetic alterations affecting tissue-specific differentiation are the predominant mechanism by which epigenetic changes cause cancer.
Nature Genetics 02/2009; 41(2):178-86. · 35.53 Impact Factor
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ABSTRACT: Chromatin status is characterized in part by covalent posttranslational modifications of histones that regulate chromatin dynamics and direct gene expression. BORIS (brother of the regulator of imprinted sites) is an insulator DNA-binding protein that is thought to play a role in chromatin organization and gene expression. BORIS is a cancer-germ line gene; these are genes normally present in male germ cells (testis) that are also expressed in cancer cell lines as well as primary tumors. This work identifies SET1A, an H3K4 methyltransferase, and BAT3, a cochaperone recruiter, as binding partners for BORIS, and these proteins bind to the upstream promoter regions of two well-characterized procarcinogenic genes, Myc and BRCA1. RNA interference (RNAi) knockdown of BAT3, as well as SET1A, decreased Myc and BRCA1 gene expression but did not affect the binding properties of BORIS, but RNAi knockdown of BORIS prevented the assembly of BAT3 and SET1A at the Myc and BRCA1 promoters. Finally, chromatin analysis suggested that BORIS and BAT3 exert their effects on gene expression by recruiting proteins such as SET1A that are linked to changes in H3K4 dimethylation. Thus, we propose that BORIS acts as a platform upon which BAT3 and SET1A assemble and exert effects upon chromatin structure and gene expression.
Molecular and cellular biology 10/2008; 28(21):6720-9. · 6.06 Impact Factor
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ABSTRACT: The CTCF paralog BORIS (brother of the regulator of imprinted sites) is an insulator DNA-binding protein thought to play a role in chromatin organization and gene expression. Under normal physiologic conditions, BORIS is predominantly expressed during embryonic male germ cell development; however, it is also expressed in tumors and tumor cell lines and, as such, has been classified as a cancer-germline or cancer-testis gene. It has been suggested that BORIS may be a pro-proliferative factor, whereas CTCF favors antiproliferation. BORIS and CTCF share similar zinc finger DNA-binding domains and seem to bind to identical target sequences. Thus, one critical question is the mechanism governing the DNA-binding specificity of these two proteins when both are present in tumor cells. Chromatin immunoprecipitation (ChIP) in HCT116 cells and their hypermethylated variant showed that BORIS binds to methylated DNA sequences, whereas CTCF binds to unmethylated DNA. Electromobility shift assays, using both whole-cell extracts and in vitro translated CTCF and BORIS protein, and methylation-specific ChIP PCR showed that BORIS is a methylation-independent DNA-binding protein. Finally, experiments in murine hybrid cells containing either the maternal or paternal human chromosome 11 showed that BORIS preferentially binds to the methylated paternal H19 differentially methylated region, suggesting a mechanism in which the affinity of CTCF for the unmethylated maternal allele directs the DNA binding of BORIS toward the paternal allele.
Cancer Research 07/2008; 68(14):5546-51. · 7.86 Impact Factor
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Hans T Bjornsson,
Martin I Sigurdsson,
M Daniele Fallin,
Rafael A Irizarry,
Thor Aspelund, Hengmi Cui,
Wenqiang Yu,
Michael A Rongione,
Tomas J Ekström,
Tamara B Harris,
Lenore J Launer,
Gudny Eiriksdottir,
Mark F Leppert,
Carmen Sapienza,
Vilmundur Gudnason,
Andrew P Feinberg
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ABSTRACT: Changes over time in epigenetic marks, which are modifications of DNA such as by DNA methylation, may help explain the late onset of common human diseases. However, changes in methylation or other epigenetic marks over time in a given individual have not yet been investigated.
To determine whether there are longitudinal changes in global DNA methylation in individuals and to evaluate whether methylation maintenance demonstrates familial clustering.
We measured global DNA methylation by luminometric methylation assay, a quantitative measurement of genome-wide DNA methylation, on DNA sampled at 2 visits on average 11 years apart in 111 individuals from an Icelandic cohort (1991 and 2002-2005) and on average 16 years apart in 126 individuals from a Utah sample (1982-1985 and 1997-2005).
Global methylation changes over time.
Twenty-nine percent of Icelandic individuals showed greater than 10% methylation change over time (P < .001). The family-based Utah sample also showed intra-individual changes over time, and further demonstrated familial clustering of methylation change (P = .003). The family showing the greatest global methylation loss also demonstrated the greatest loss of gene-specific methylation by a separate methylation assay.
These data indicate that methylation changes over time and suggest that methylation maintenance may be under genetic control.
JAMA The Journal of the American Medical Association 06/2008; 299(24):2877-83. · 30.03 Impact Factor
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Lunching Sun,
Lei Huang,
Phuongmai Nguyen,
Kheem S Bisht,
Gil Bar-Sela,
Allen S Ho,
C Matthew Bradbury,
Wenqiang Yu, Hengmi Cui,
Sunmin Lee,
Jane B Trepel,
Andrew P Feinberg,
David Gius
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ABSTRACT: In a previous genomic analysis, using somatic methyltransferase (DNMT) knockout cells, we showed that hypomethylation decreased the expression of as many genes as were observed to increase, suggesting a previously unknown mechanism for epigenetic regulation. To address this idea, the expression of the BAG family genes was used as a model. These genes were used because their expression was decreased in DNMT1(-/-), DNMT3B(-/-), and double knockout cells and increased in DNMT1-overexpressing and DNMT3B-overexpressing cells. Chromatin immunoprecipitation analysis of the BAG-1 promoter in DNMT1-overexpressing or DNMT3B-overexpressing cells showed a permissive dimethyl-H3-K4/dimethyl-H3-K9 chromatin status associated with DNA-binding of CTCFL/BORIS, as well as increased BAG-1 expression. In contrast, a nonpermissive dimethyl-H3-K4/dimethyl-H3-K9 chromatin status was associated with CTCF DNA-binding and decreased BAG-1 expression in the single and double DNMT knockout cells. BORIS short hairpin RNA knockdown decreased both promoter DNA-binding, as well as BAG-1 expression, and changed the dimethyl-H3-K4/dimethyl-H3-K9 ratio to that characteristic of a nonpermissive chromatin state. These results suggest that DNMT1 and DNMT3B regulate BAG-1 expression via insulator protein DNA-binding and chromatin dynamics by regulating histone dimethylation.
Cancer Research 05/2008; 68(8):2726-35. · 7.86 Impact Factor
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ABSTRACT: An unexpected outcome of the diploid genome is that evolutionary strategies have evolved to express only one of the alleles
(1). The rapidly expanding list of genes that are expressed monoallelically fall into three main categories: random inactivation,
allelic exclusion, and genomic imprinting. These categories are distinguished by whether the expressed and inactivated alleles
are maintained from one cell division to the next (random inactivation occurs with each cell division, compared to stable
propagation through subsequent cell divisions as seen for allelic exclusion and genomic imprinting) and whether allele inactivation
or expression is determined by parent of origin of inheritance (this differentiates allelic exclusion from genomic imprinting).
Genomically imprinted genes are currently more numerous than members of the other categories. This fact is likely to reflect
that the persistent (in)activation of one allele in a parent of origin-specific manner has facilitated the detection of monoallelic
expression patterns in RNA extracted from homogenized tissue. This crude approach does not take into account, however, different
imprinted states within a tissue, or, indeed, random allelic (in)activation. It is not surprising, therefore, that well-known
genes, such as Il2 (2), were only recently found to be monoallelically expressed in a random manner (1).
02/2008: pages 153-167;
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ABSTRACT: Tumour suppressor genes (TSGs) inhibiting normal cellular growth are frequently silenced epigenetically in cancer. DNA methylation is commonly associated with TSG silencing, yet mutations in the DNA methylation initiation and recognition machinery in carcinogenesis are unknown. An intriguing possible mechanism for gene regulation involves widespread non-coding RNAs such as microRNA, Piwi-interacting RNA and antisense RNAs. Widespread sense-antisense transcripts have been systematically identified in mammalian cells, and global transcriptome analysis shows that up to 70% of transcripts have antisense partners and that perturbation of antisense RNA can alter the expression of the sense gene. For example, it has been shown that an antisense transcript not naturally occurring but induced by genetic mutation leads to gene silencing and DNA methylation, causing thalassaemia in a patient. Here we show that many TSGs have nearby antisense RNAs, and we focus on the role of one RNA in silencing p15, a cyclin-dependent kinase inhibitor implicated in leukaemia. We found an inverse relation between p15 antisense (p15AS) and p15 sense expression in leukaemia. A p15AS expression construct induced p15 silencing in cis and in trans through heterochromatin formation but not DNA methylation; the silencing persisted after p15AS was turned off, although methylation and heterochromatin inhibitors reversed this process. The p15AS-induced silencing was Dicer-independent. Expression of exogenous p15AS in mouse embryonic stem cells caused p15 silencing and increased growth, through heterochromatin formation, as well as DNA methylation after differentiation of the embryonic stem cells. Thus, natural antisense RNA may be a trigger for heterochromatin formation and DNA methylation in TSG silencing in tumorigenesis.
Nature 02/2008; 451(7175):202-6. · 36.28 Impact Factor
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William C Reinhold,
Mark A Reimers,
Alika K Maunakea,
Sohyoung Kim,
Samir Lababidi,
Uwe Scherf,
Uma T Shankavaram,
Micah S Ziegler,
Claudia Stewart,
Hosein Kouros-Mehr, Hengmi Cui,
Douglas Dolginow,
Dominic A Scudiero,
Yves G Pommier,
David J Munroe,
Andrew P Feinberg,
John N Weinstein
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ABSTRACT: E-cadherin (E-cad) is a transmembrane adhesion glycoprotein, the expression of which is often reduced in invasive or metastatic tumors. To assess E-cad's distribution among different types of cancer cells, we used bisulfite-sequencing for detailed, base-by-base measurement of CpG methylation in E-cad's promoter region in the NCI-60 cell lines. The mean methylation levels of the cell lines were distributed bimodally, with values pushed toward either the high or low end of the methylation scale. The 38 epithelial cell lines showed substantially lower (28%) mean methylation levels compared with the nonepithelial cell lines (58%). The CpG site at -143 with respect to the transcriptional start was commonly methylated at intermediate levels, even in cell lines with low overall DNA methylation. We also profiled the NCI-60 cell lines using Affymetrix U133 microarrays and found E-cad expression to be correlated with E-cad methylation at highly statistically significant levels. Above a threshold of approximately 20% to 30% mean methylation, the expression of E-cad was effectively silenced. Overall, this study provides a type of detailed analysis of methylation that can also be applied to other cancer-related genes. As has been shown in recent years, DNA methylation status can serve as a biomarker for use in choosing therapy.
Molecular Cancer Therapeutics 03/2007; 6(2):391-403. · 5.23 Impact Factor
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Hengmi Cui
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ABSTRACT: IGF2 is the first gene discovered to be imprinted and expressed exclusively from the paternal allele in both human and mouse. IGF2 is also the first imprinted gene displaying loss of imprinting (LOI) or aberrant imprinting in human cancers. Evidently, LOI or reactivation of the maternal allele of IGF2 is associated with an increase of IGF2 expression that may subsequently play an important role in the onset of human cancers. The most important discovery was the association of LOI of IGF2 with the risk of developing human colorectal cancer. LOI occurs not only in colon cancer tissues, but also in matched normal tissues and peripheral blood cells. A pilot study indicated a significant relationship between LOI of IGF2 and family history as well as personal history of colorectal cancer, suggesting that LOI of IGF2 might be a valuable biomolecular marker of predicting an individual's risk for colon cancer. A recent epigenetic progenitor model suggested that human cancers might have a common basis that involves an epigenetic disruption of progenitor cells mediated by "tumor progenitor genes" and proposed that non-neoplastic but epigenetically disrupted progenitor cells might be an important target for cancer risk assessment and prevention.
Disease markers 02/2007; 23(1-2):105-12. · 1.64 Impact Factor
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ABSTRACT: To evaluate the feasibility and superiority of comparative genomic hybridization (CGH) in the genetic analysis of spontaneously aborted tissues.
38 conceptuses from early failed pregnancies were studied, of which, 27 samples were fresh and 11 were old. Each sample was divided into two parts, one part for conventional cytogenetic analysis and the other for CGH analysis.
All 38 spontaneously aborted tissues were analyzed successfully by the CGH approach, but only 31 samples received results from the cytogenetic karyotype analysis, while 7 other tissues failed to get data due to failure in tissue culturing. Among the specimen successfully analyzed by both approaches, 90% (28 out of 31) obtained identical results, and 14 aneuploidies were found. The only structural chromosome aberration in this series, 46, XY, del(3) (q22-24), was found using the CGH approach, which appeared as a normal male karyotype on the chromosomal metaphase spread. Also, two cases indicated triploidies under cytogenetic analysis but appeared to be normal on the CGH profile. In addition, among the seven samples of tissue culture failure, CGH identified three to be aneuploidies.
The CGH analysis accurately identifies chromosomal unbalanced abnormalities related to spontaneous abortions with low failure rate.
International Journal of Gynecology & Obstetrics 02/2006; 92(1):52-7. · 2.05 Impact Factor
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David Gius, Hengmi Cui,
C Matthew Bradbury,
John Cook,
Deedee K Smart,
Shuping Zhao,
Lynn Young,
Sheri A Brandenburg,
Yali Hu,
Kheem S Bisht,
Allen S Ho,
David Mattson,
Lunching Sun,
Peter J Munson,
Eric Y Chuang,
James B Mitchell,
Andrew P Feinberg
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ABSTRACT: We tested the hypothesis that the effects on gene expression of altered DNA methylation by 5-aza-2'-deoxycytidine (5-aza-CdR) and genetic (DNMT knockout) manipulation of DNA are similar, and distinct from Trichostatin A (TSA)-induced chromatin decondensation. Surprisingly, the effects of 5-aza-CdR were more similar to those of TSA than to DNMT1, DNMT3B, or double DNMT somatic cell knockout. Furthermore, the effects of 5-aza-CdR were similar at one and five days exposure, suggesting active demethylation or direct influence of both drugs on the stability of methylation and/or chromatin marks. Agents that induce gene activation through hypomethylation may have unintended consequences, since nearly as many genes were downregulated as upregulated after demethylation. In addition, a 75 kb cluster of metallothionein genes was coordinately regulated.
Cancer Cell 11/2004; 6(4):361-71. · 26.57 Impact Factor
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ABSTRACT: Dendritic cells (DCs) link innate and adaptive immunity by sensing pathogens or vaccinogens and signaling a variety of defense responses. Since human papillomavirus type 16 L1 virus-like particles (HPV16 VLPs) induce a potent, protective immune response after vaccination, we examined their recognition by DCs. HPV16 VLPs cause phenotypic maturation of murine bone marrow-derived DCs (BMDCs), and immunization of mice with HPV16 VLP-loaded BMDCs or HPV16 VLPs alone induced T helper 1 (Th1)-biased immune responses. Analysis of transcriptional responses of murine BMDCs by microarray suggested that alpha/beta interferon (IFN-alpha/beta) transcripts and numerous proinflammatory cytokines and chemokines are up regulated in response to HPV16 VLPs. Indeed, the induction of IFN-alpha, IFN-gamma, and interleukin-12 (IL-12) production by BMDCs after stimulation with HPV16 VLPs was demonstrated by quantitative enzyme-linked immunosorbent assay. Many microbial products that induce proinflammatory responses are recognized via Toll-like receptor (TLR) signaling through the key adaptor protein MyD88 and activation of NF-kappaB, nuclear factor of activated T cells (NF-AT), and activating protein 1 (AP-1). Reporter assays indicated that HPV16 VLPs activated NF-kappaB-, NF-AT-, and AP-1-dependent transcription in the RAW264.7 macrophage cell line. Knockdown of MyD88 transcripts by small interfering RNA in the RAW264.7 macrophage cell line inhibited the activation of NF-kappaB-, NF-AT- and AP-1-dependent transcription by HPV16 VLP. Furthermore, MyD88(-/-) BMDCs failed to up regulate IL-12 and IFN-alpha and -gamma in response to HPV16 VLPs. Finally, Th1-biased immune responses to HPV16 VLPs are dramatically impaired in MyD88 and IFN-alpha/beta receptor-deficient mice. This implicates TLR recognition as central to immune recognition of HPV16 L1 VLPs.
Journal of Virology 11/2004; 78(20):11152-60. · 5.40 Impact Factor
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ABSTRACT: To develop a reliable and specific technique for rapid prenatal diagnosis of Down syndrome.
High throughput real-time PCR technique was used to measure the DSCR3 gene dosage of genomic DNAs from uncultured amniocytes of fetuses, lymphocytes of trisomy 21 syndrome patients, and normal people, compared to conventional cytogenetic karyotype analysis.
The DSCR3/GAPDH ratio of uncultured amniocytes in trisomy 21 syndrome fetuses to normal fetuses was 1.69 +/- 0.17 to 1.06 +/- 0.14, respectively (p < 0.001); and the DSCR3/GAPDH ratio of lymphocytes in trisomy 21 syndrome children to normal people was 1.67 +/- 0.13 to 0.99 +/- 0.10, respectively (p < 0.001). Real-time PCR technique effectively differentiates the normal fetuses from the trisomy 21 syndrome fetuses; therefore, compared to the results of the conventional cytogenetic karyotype analysis, the DSCR3/GAPDH ratios of trisomy 21 syndrome fetuses are significantly higher than those of normal fetuses.
Because the DSCR3/GAPDH ratio of trisomy 21 syndrome fetuses is significantly higher than that of normal fetuses, the genomic DNA real-time PCR technique may be a reliable and specific method for the rapid prenatal diagnosis of Down syndrome.
Prenatal Diagnosis 10/2004; 24(9):704-7. · 2.11 Impact Factor
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Marcia Cruz-Correa, Hengmi Cui,
Francis M Giardiello,
Neil R Powe,
Linda Hylind,
Angela Robinson,
David F Hutcheon,
David R Kafonek,
Sheri Brandenburg,
Yiqian Wu,
Xiaobing He,
Andrew P Feinberg
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ABSTRACT: Loss of genomic imprinting (LOI) of insulin-like growth factor II gene (IGF2) involves abnormal activation of the normally silent maternally inherited allele. LOI of IGF2 has been associated with personal and family history of colorectal neoplasia (CRN), supporting a role for LOI in colorectal carcinogenesis. Whether LOI of IGF2 is associated with known environmental risk factors for CRN is unknown.
We performed quantitative hot-stop PCR for imprinting analysis of IGF2 on normal peripheral blood lymphocytes (PBL) of individuals. Environmental exposures including tobacco, alcohol, NSAIDs, and nutrient consumption (calcium, folate, selenium, fiber, and fat) were correlated with LOI expression in PBL. Odds ratios (OR) and 95% CI were calculated.
The prevalence of LOI of IGF2 was examined in 172 individuals. Persons with CRN (adenomas/cancer) had 5.1-fold (95% CI: 1.92-13.6) increased risk of having LOI of IGF2 in PBL compared with those without CRN. In contrast, tobacco smoking (OR = 0.96, 95% CI: 0.36-2.55), alcohol consumption (OR = 1.22, 95% CI: 0.45-3.3), and NSAIDs use (OR = 1.21, 95% CI: 0.38-3.94) were not significantly associated with LOI of IGF2. Nutrient ingestion including calcium (P = 0.61), folate (P = 0.23), selenium (P = 0.19), fiber (P = 0.63), and fat (P = 0.14) was not statistically correlated with LOI of IGF2.
Abnormal imprinting of IGF2 gene was strongly associated with CRN but not with any of the environmental exposures examined. LOI of IGF2 does not appear to be an environmentally acquired phenomenon but rather a hereditary risk factor for CRN.
Gastroenterology 04/2004; 126(4):964-70. · 11.68 Impact Factor
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ABSTRACT: Loss of imprinting (LOI), an epigenetic alteration affecting the insulin-like growth factor II gene (IGF2), is found in normal colonic mucosa of about 30% of colorectal cancer (CRC) patients, but it is found in only 10% of healthy individuals. In a pilot study to investigate the utility of LOI as a marker of CRC risk, we evaluated 172 patients at a colonoscopy clinic. The adjusted odds ratio for LOI in lymphocytes was 5.15 for patients with a positive family history [95% confidence interval (95% CI), 1.70 to 16.96; probability P = 0.002], 3.46 for patients with adenomas (95% CI, 1.14 to 11.37; P = 0.026), and 21.7 for patients with CRC (95% CI, 3.48 to 153.6; P = 0.0005). LOI can be assayed with a DNA-based blood test, and it may be a valuable predictive marker of an individual's risk for CRC.
Science 04/2003; 299(5613):1753-5. · 31.20 Impact Factor
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ABSTRACT: Epigenetic alterations in human cancers include global DNA hypomethylation,gene hypomethylation and promoter hypermethylation, and loss of imprinting (LOI) of the insulin-like growth factor-II gene (IGF2). A mechanism for LOI described previously is hypermethylation of a differentially methylated region (DMR) upstream of the H19 gene, allowing activation of the normally silent maternal allele of IGF2. Here we show that this mechanism does not apply to colorectal cancers, which show hypomethylation of the H19 DMR as well as a DMR upstream of exon 3 of IGF2. This hypomethylation is found in both colorectal cancers and normal mucosa from the same patients, and in cell lines with somatic cell knockout of DNA methyltransferases DNMT1 and DNMT3B. These data suggest that hypomethylation is a mechanism for LOI, that the popular IGF2-H19 enhancer competition model for IGF2 imprinting does not apply to the human colon, and that an alternative model for LOI would involve a transcriptional repressor acting on the normally silent maternal allele of IGF2.
Cancer Research 12/2002; 62(22):6442-6. · 7.86 Impact Factor
