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Bose S, Starczynski J, Chukwuma M, Baumforth K, Wei W, Morgan S, Byrd P, Ying J, Grundy R, Mann JR, Tao Q, Taylor AMR, Murray PG, Stankovic T. Down-regulation of ATM protein in HRS cells of nodular sclerosis Hodgkin's lymphoma in children occurs in the absence ofATMgene inactivation. J Pathol 2007; 213:329-36. [PMID: 17876757 DOI: 10.1002/path.2232] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The tumour component of classical Hodgkin's lymphoma (cHL), Hodgkin Reed-Sternberg (HRS) cells, are believed to be derived from germinal centre (GC) B cells but intriguingly display a characteristic loss of B cell receptor (BCR) expression. The precise mechanisms by which BCR-negative HRS cell progenitors survive negative selection during the GC reaction remain obscure. Individuals with ataxia telangiectasia, caused by biallelic inactivation of the DNA damage response gene, ataxia telangiectasia mutated (ATM), have a higher risk of cHL development. Here we show that, in contrast to normal GC B cells that expressed low but detectable ATM protein, ATM protein was not detected in HRS cells of 17/18 cases of paediatric cHL, all but one with nodular sclerosis (NS) subtype. A comprehensive analysis of the ATM gene in microdissected HRS cells of nine representative tumours showed no evidence of either loss of heterozygosity or consistent pathogenic mutations. Furthermore, bisulphite sequencing of the ATM promoter from HRS cells of five tumours also revealed the absence of hypermethylation. Since our microarray data suggested significantly reduced ATM transcription in HRS cells compared to GC B cells, we conclude that loss of ATM expression could be the result of alterations in upstream regulators of ATM transcription. Importantly, ATM loss in paediatric cHLs has clinical implications and could be potentially exploited to guide future, less toxic, tumour-specific treatments.
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Cheng YY, Yu J, Wong YP, Man EPS, To KF, Jin VX, Li J, Tao Q, Sung JJY, Chan FKL, Leung WK. Frequent epigenetic inactivation of secreted frizzled-related protein 2 (SFRP2) by promoter methylation in human gastric cancer. Br J Cancer 2007; 97:895-901. [PMID: 17848950 PMCID: PMC2360406 DOI: 10.1038/sj.bjc.6603968] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The role of secreted frizzled-related protein (SFRP) genes in gastric cancer remains largely unknown. We determined the frequency and functional significance of SFRPs hypermethylation in human gastric cancer. The expression and methylation status of four SFRP members (SFRP1, 2, 4, and 5) in primary gastric cancer samples was screened. The biological effects of SFRP were analysed by flow cytometry, cell viability assay and in vivo tumour growth in nude mice. Among the four SFRPs, only SFRP2 was significantly downregulated in gastric cancer as compared to adjacent non-cancer samples (P<0.01). Promoter hypermethylation of SFRP2 was detected in 73.3% primary gastric cancer tissues, 37.5% of samples showing intestinal metaplasia and 20% adjacent normal gastric tissues. Bisulphite DNA sequencing confirmed the densely methylated SFRP2 promoter region. Demethylation treatment restored the expression of SFRP2 in gastric cancer cell lines. Forced expression of SFRP2 induced cell apoptosis, inhibited proliferation of gastric cancer cells and suppressed tumour growth in vivo. Moreover, methylated SFRP2 was detected in 66.7% of serum samples from cancer patients but not in normal controls. In conclusion, epigenetic inactivation of SFRP2 is a common and early event contributing to gastric carcinogenesis and may be a potential biomarker for gastric cancer.
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Law FBF, Chen YW, Wong KY, Ying J, Tao Q, Langford C, Lee PY, Law S, Cheung RWL, Chui CH, Tsao GSW, Lam KY, Wong J, Srivastava G, Tang JCO. Identification of a novel tumor transforming gene GAEC1 at 7q22 which encodes a nuclear protein and is frequently amplified and overexpressed in esophageal squamous cell carcinoma. Oncogene 2007; 26:5877-88. [PMID: 17384685 PMCID: PMC2875854 DOI: 10.1038/sj.onc.1210390] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Revised: 01/15/2007] [Accepted: 02/07/2007] [Indexed: 12/13/2022]
Abstract
By comparative DNA fingerprinting, we identified a 357-bp DNA fragment frequently amplified in esophageal squamous cell carcinomas (ESCC). This fragment overlaps with an expressed sequence tag mapped to 7q22. Further 5' and 3'-rapid amplification of cDNA ends revealed that it is part of a novel, single-exon gene with full-length mRNA of 2052 bp and encodes a nuclear protein of 109 amino acids ( approximately 15 kDa). This gene, designated as gene amplified in esophageal cancer 1 (GAEC1), was located within a 1-2 Mb amplicon at 7q22.1 identified by high-resolution 1 Mb array-comparative genomic hybridization in 6/10 ESCC cell lines. GAEC1 was ubiquitously expressed in normal tissues including esophageal and gastrointestinal organs; with amplification and overexpression in 6/10 (60%) ESCC cell lines and 34/99 (34%) primary tumors. Overexpression of GAEC1 in 3T3 mouse fibroblasts caused foci formation and colony formation in soft agar, comparable to H-ras and injection of GAEC1-transfected 3T3 cells into athymic nude mice formed undifferentiated sarcoma in vivo, indicating that GAEC1 is a transforming oncogene. Although no significant correlation was observed between GAEC1 amplification and clinicopathological parameters and prognosis, our study demonstrated that overexpressed GAEC1 has tumorigenic potential and suggest that overexpressed GAEC1 may play an important role in ESCC pathogenesis.
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Lee S, Mok T, Li H, Yim A, Wan I, Lam KC, Chan A, To KF, Tao Q. Possible correlation between SOCS1 methylation and EGFR exon 19 mutation but not exon 21 mutation in Chinese NSCLC patients. J Clin Oncol 2007. [DOI: 10.1200/jco.2007.25.18_suppl.18113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
18113 Background: Suppressor of cytokine signaling-1 (SOCS1) and -3 (SOCS3) interact with the epidermal growth factor receptor (EGFR) to bring about the ubiquination and degradation of the receptor. Silencing of SOCS1 and SOCS3 by methylation was postulated to regulate the IL-6R/JAK-mediated STAT3 activation. Its relationship to EGFR and EGFR mutations in lung cancer remains unclear. Here, we examined the relationship between EGFR mutations and methylation of SOCS1 and SOCS3 in Chinese NSCLC patients. Methods: EGFR mutations were assessed in DNAs from microdissected tumor cells. PCR products were purified and sequenced using the BigDye Terminator Cycle Sequencing Kit (Applied Biosystem) and the ABI 3100 Genetic Analyzer. For methylation analyses of SOCS1 and SOCS3, DNAs were extracted from paraffin sections of tumor tissues, bisulfite treated and analyzed by methylation- specific PCR (MSP). Results: Data is available from 9 lung cancer cell lines and 20 tumor samples. Five EGFR-wild type cell lines had methylation for SOCS1. We found EGFR exon 19 mutation in 5 (25%) tumors, exon 21 mutation (L858R) in 2 (10%) tumors, and 1 (5%) tumor had double mutations. Four of 5 (80%) tumors with exon 19 mutation and none (0%) of the tumors with exon 21 mutation had SOCS1 methylation, comparing to only 2 of 12 (17%) EGFR-wild type tumors had SOCS1 methylation. SOCS3 methylation was not detected in any of the primary tumors or cell lines. Conclusions: Our preliminary findings suggest that SOCS1 methylation might be positively correlated with EGFR exon 19 mutation but exclusive from exon 21 mutation. A following study with larger sample size is currently under way. SOCS1 methylation may explain the better tumor response associated with EGFR exon 19 mutation. No significant financial relationships to disclose.
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Soo R, Wu J, Aggarwal A, Tao Q, Hsieh W, Putti T, Tan K, Soon W, Lai Y, Mow B, Hsu S, Loh K, Tan L, Tan P, Goh BC. Correction to: Celecoxib reduces microvessel density in patients treated with nasopharyngeal carcinoma and induces changes in gene expression. Ann Oncol 2006; 17: 1625–1630. Ann Oncol 2007. [DOI: 10.1093/annonc/mdm054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Soo RA, Wu J, Aggarwal A, Tao Q, Hsieh W, Putti T, Tan KB, Low JSW, Soon WL, Lai YF, Mow B, Hsu S, Loh KS, Tan L, Tan P, Goh BC. Celecoxib reduces microvessel density in patients treated with nasopharyngeal carcinoma and induces changes in gene expression. Ann Oncol 2006; 17:1625-30. [PMID: 17008411 DOI: 10.1093/annonc/mdl283] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Celecoxib is a selective cyclooxygenase-2 inhibitor with antitumor and antiangiogenic activity. We sought to determine pharmacodynamic change in tumors of patients with nasopharyngeal carcinoma (NPC) treated with celecoxib. METHODS Tumor biopsies were obtained before and after treatment with celecoxib 400 mg b.i.d. for 14 days in patients with newly diagnosed, untreated NPC. Tumor angiogenesis and cell proliferation were assessed by immunohistochemistry and gene expression by microarray analysis. Plasma celecoxib concentrations were obtained on days 8 and 14. RESULTS Paired samples were analyzed in 15 patients. Microvessel density was reduced in post-treatment samples and mean celecoxib levels reached therapeutic levels. Thirty-five genes (27 down-regulated, eight up-regulated) were differentially expressed on microarray analysis (p < 0.001). Down-regulated genes included cell cycle regulation-related (cyclin-dependent kinase 2, YES1), transcription factor (TRIP-Br2), whereas the antigen processing and presentation-related gene HLA-DM B was up-regulated. CONCLUSION Celecoxib reduced angiogenesis and induced tumor transcriptional changes. Further characterization of these transcriptional changes in vivo is needed to provide further insights into the effects of celecoxib in neoplastic tissue. Our findings provide a rationale for clinical studies aimed at assessing the efficacy of celecoxib in the treatment of NPC.
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Seng TJ, Low JSW, Li H, Cui Y, Goh HK, Wong MLY, Srivastava G, Sidransky D, Califano J, Steenbergen RDM, Rha SY, Tan J, Hsieh WS, Ambinder RF, Lin X, Chan ATC, Tao Q. The major 8p22 tumor suppressor DLC1 is frequently silenced by methylation in both endemic and sporadic nasopharyngeal, esophageal, and cervical carcinomas, and inhibits tumor cell colony formation. Oncogene 2006; 26:934-44. [PMID: 16862168 DOI: 10.1038/sj.onc.1209839] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Identification of tumor suppressor genes (TSG) silenced by methylation uncovers mechanisms of tumorigenesis and identifies new epigenetic tumor markers for early cancer detection. Both nasopharyngeal carcinoma (NPC) and esophageal carcinoma are major tumors in Southern China and Southeast Asia. Through expression subtraction of NPC, we identified Deleted in Liver Cancer 1 (DLC1)/ARHGAP7 (NM_006094)--an 8p22 TSG as a major downregulated gene. Although expressed in all normal tissues, DLC1 was silenced or downregulated in 11/12 (91%) NPC, 6/15 (40%) esophageal, 5/8 (63%) cervical and 3/9 (33%) breast carcinoma cell lines. No genetic deletion of DLC1 was detected in NPC although a hemizygous deletion at 8p22-11 was found by 1-Mb array-CGH in some cell lines. We then located the functional DLC1 promoter by 5'-RACE and promoter activity assays. This promoter was frequently methylated in all downregulated cell lines and in a large collection of primary tumors including 89% (64/72) NPC (endemic and sporadic types), 51% (48/94) esophageal, 87% (7/8) cervical and 36% (5/14) breast carcinomas, but seldom in paired surgical marginal tissues and not in any normal epithelial tissue. The transcriptional silencing of DLC1 could be reversed by 5-aza-2'-deoxycytidine or genetic double knock-out of DNMT1 and DNMT3B. Furthermore, ectopic expression of DLC1 in NPC and esophageal carcinoma cells strongly inhibited their colony formation. We thus found frequent epigenetic silencing of DLC1 in NPC, esophageal and cervical carcinomas, and a high correlation of methylation with its downregulation, suggesting a predominant role of epigenetic inactivation. DLC1 appears to be a major TSG implicated in the pathogenesis of these tumors, and should be further tested as a molecular biomarker in patients with these cancers.
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Ying J, Li H, Cui Y, Wong AHY, Langford C, Tao Q. Epigenetic disruption of two proapoptotic genes MAPK10/JNK3 and PTPN13/FAP-1 in multiple lymphomas and carcinomas through hypermethylation of a common bidirectional promoter. Leukemia 2006; 20:1173-5. [PMID: 16572203 DOI: 10.1038/sj.leu.2404193] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Yeo W, Chan L, Wong W, Tao Q. Methylation status of WIF-1 promoter region in breast cancer cell lines and tumour tissues. EUROPEAN JOURNAL OF CANCER SUPPLEMENTS 2006. [DOI: 10.1016/s1359-6349(06)80328-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Ying J, Li H, Seng TJ, Langford C, Srivastava G, Tsao SW, Putti T, Murray P, Chan ATC, Tao Q. Functional epigenetics identifies a protocadherin PCDH10 as a candidate tumor suppressor for nasopharyngeal, esophageal and multiple other carcinomas with frequent methylation. Oncogene 2006; 25:1070-80. [PMID: 16247458 DOI: 10.1038/sj.onc.1209154] [Citation(s) in RCA: 215] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2005] [Revised: 08/24/2005] [Accepted: 08/24/2005] [Indexed: 12/12/2022]
Abstract
Protocadherins constitute the largest subgroup in the cadherin superfamily of cell adhesion molecules. Their major functions are poorly understood, although some are implicated in nervous system development. As tumor-specific promoter methylation is a marker for tumor suppressor genes (TSG), we searched for epigenetically inactivated TSGs using methylation-subtraction combined with pharmacologic demethylation, and identified the PCDH10 CpG island as a methylated sequence in nasopharyngeal carcinoma (NPC). PCDH10 is broadly expressed in all normal adult and fetal tissues including the epithelia, though at different levels. It resides at 4q28.3--a region with hemizygous deletion detected by array-CGH in NPC cell lines; however, PCDH10 itself is not located within the deletion. In contrast, its transcriptional silencing and promoter methylation were frequently detected in multiple carcinoma cell lines in a biallelic way, including 12/12 nasopharyngeal, 13/16 esophageal, 3/4 breast, 5/5 colorectal, 3/4 cervical, 2/5 lung and 2/8 hepatocellular carcinoma cell lines, but not in any immortalized normal epithelial cell line. Aberrant methylation was further frequently detected in multiple primary carcinomas (82% in NPC, 42-51% for other carcinomas), but not normal tissues. The transcriptional silencing of PCDH10 could be reversed by pharmacologic demethylation with 5-aza-2'-deoxycytidine or genetic demethylation with double knockout of DNMT1 and DNMT3B, indicating a direct epigenetic mechanism. Ectopic expression of PCDH10 strongly suppressed tumor cell growth, migration, invasion and colony formation. Although the epigenetic and genetic disruptions of several classical cadherins as TSGs have been well documented in tumors, this is the first report that a widely expressed protocadherin can also function as a TSG that is frequently inactivated epigenetically in multiple carcinomas.
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li C, Pang Y, Tao Q, Wang D. Relationship Between Promoter Methylation of Multiple Genes and inflammatory Cell infiltration in Nasal Polyps. J Allergy Clin Immunol 2006. [DOI: 10.1016/j.jaci.2005.12.292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Varvel SA, Bridgen DT, Tao Q, Thomas BF, Martin BR, Lichtman AH. Delta9-tetrahydrocannbinol accounts for the antinociceptive, hypothermic, and cataleptic effects of marijuana in mice. J Pharmacol Exp Ther 2005; 314:329-37. [PMID: 15831444 DOI: 10.1124/jpet.104.080739] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although it is widely accepted that delta9-tetrahydrocannabinol (delta9-THC) is the primary psychoactive constituent of marijuana, questions persist as to whether other components contribute to marijuana's pharmacological activity. The present experiments assessed the cannabinoid activity of marijuana smoke exposure in mice and tested the hypothesis that delta9-THC mediates these effects through a CB1 receptor mechanism of action. First, the effects of delta9-THC on analgesia, hypothermia, and catalepsy were compared with those of a marijuana extract with equated delta9-THC content after either i.v. administration or inhalation exposure. Second, mice were exposed to smoke of an ethanol-extracted placebo plant material or low-grade marijuana (with minimal delta9-THC but similar levels of other cannabinoids) that were impregnated with varying quantities of delta9-THC. To assess doses, delta9-THC levels in the blood and brains of drug-exposed mice were determined following both i.v. and inhalation routes of administration. Both marijuana and delta9-THC produced comparable levels of antinociception, hypothermia, and catalepsy regardless of the route of administration, and these effects were blocked by pretreatment with the CB1 antagonist SR141716 [N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide HCl]. Importantly, the blood and brain levels of delta9-THC were similar in mice exhibiting similar pharmacological effects, regardless of the presence of non-delta9-THC marijuana constituents. The present experiments provide evidence that the acute cannabinoid effects of marijuana smoke exposure on analgesia, hypothermia, and catalepsy in mice result from delta9-THC content acting at CB1 receptors and that the non-delta9-THC constituents of marijuana (at concentrations relevant to those typically consumed) influence these effects only minimally, if at all.
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Dai H, Chen J, Tao Q, Zhu J, Zhang F, Zheng L, Qiu Y. Effects of diltiazem on platelet activation and cytosolic calcium during percutaneous transluminal coronary angioplasty. Postgrad Med J 2003; 79:522-6. [PMID: 13679549 PMCID: PMC1742832 DOI: 10.1136/pmj.79.935.522] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIMS To evaluate effects of diltiazem on platelet hyper-reactivity in situations associated with endothelial injury and their possible relationship to cytosolic calcium concentration. METHODS Blood samples were collected at seven time points from 35 patients undergoing percutaneous transluminal coronary angioplasty (PTCA) who received combined diltiazem and aspirin/ticlopidine therapy or aspirin/ticlopidine therapy alone. Platelet expression of glycoprotein IIb/IIIa and P-selectin, production of thromboxane B(2), and cytosolic calcium concentration were measured, respectively, by whole blood flow cytometry, radioimmunoassay, and fluorospectrophotometry. The effects of diltiazem of different concentrations on expression of glycoprotein IIb/IIIa and P-selectin were also studied in vitro in blood samples from patients with chronic stable angina. RESULTS Of the two treatments, aspirin/ticlopidine therapy did not prevent an acute increase of expression of glycoprotein IIb/IIIa and P-selectin and plasma thromboxane B(2) five minutes and 10 minutes after first inflation and 10 minutes after PTCA, whereas combined diltiazem and aspirin/ticlopidine therapy had a significant inhibitory effect. In the group receiving aspirin/ticlopidine therapy, there was a short term increase of platelet [Ca(2+)](i) immediately after PTCA which was significantly reduced by diltiazem treatment. Expression of glycoprotein IIb/IIIa and P-selectin was significantly inhibited in vitro by diltiazem in the concentration of 200 ng/ml or higher, but not 50 ng/ml. CONCLUSIONS Combined diltiazem and aspirin/ticlopidine therapy significantly inhibited platelet activation that continued in the presence of conventional aspirin/ticlopidine treatment. Antiplatelet effects of diltiazem were probably a consequence of reduction of platelet [Ca(2+)](i) and may only be achieved in higher than therapeutic concentrations.
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Tao Q, Wang A, Zhang HB. One large-insert plant-transformation-competent BIBAC library and three BAC libraries of Japonica rice for genome research in rice and other grasses. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2002; 105:1058-1066. [PMID: 12582934 DOI: 10.1007/s00122-002-1057-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2001] [Accepted: 02/18/2002] [Indexed: 05/24/2023]
Abstract
We report one large-insert BIBAC library and three BAC libraries for japonica rice cv Nipponbare. The BIBAC library was constructed in the HindIII site of a plant-transformation-competent binary vector (pCLD04541) and the three BAC libraries were constructed in the BamHI, HindIII and EcoRI sites of a BAC vector (pECBAC1), respectively. Each library contains 23,040 clones, has an average insert size of 130 kb, 170 kb, 150 kb and 156 kb, and covers 6.7x, 8.7x, 7.7x and 8.0 x rice haploid genomes, respectively. The combined libraries contain 92,160 clones in total, covering 31.1 x rice haploid genomes. To demonstrate their utility, we screened the libraries with 55 DNA markers mapped to chromosome 8 of the rice genetic maps and analyzed a number of clones by the restriction fingerprinting and contig assembly method. The results indicate that the libraries completely cover the rice genome and, thus, are well-suited for genome research in rice and other gramineous crops. The BIBAC library represents the first plant-transformation-competent large-insert DNA library for rice, which will streamline map-based cloning, functional analysis of the rice genome sequence and molecular breeding in rice and other grass species. These libraries are being used in the development of a whole-genome, BAC/BIBAC-based, integrated physical, genetic and sequence map of rice and in the research of genome-wide comparative genomics of grass species.
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Tao Q, Stone DJ, Borenstein MR, Codd EE, Coogan TP, Desai-Krieger D, Liao S, Raffa RB. Differential tramadol and O-desmethyl metabolite levels in brain vs. plasma of mice and rats administered tramadol hydrochloride orally. J Clin Pharm Ther 2002; 27:99-106. [PMID: 11975693 DOI: 10.1046/j.1365-2710.2002.00384.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To investigate a possible differential brain uptake of tramadol vs. its major metabolite (O-desmethyl tramadol; M1) in mice and rats. METHODS An extraction and measurement technique (gas chromatograph equipped with a nitrogen phosphorus detector) was used to measure plasma and brain levels of tramadol and M1 at intervals 10-300 min after oral dosing of tramadol hydrochloride to mice and rats. RESULTS For all doses of tramadol administered (5, 10, 20, or 40 mg/kg), tramadol and M1 plasma levels were greatest 10 min after dosing: in mice, peak tramadol plasma levels were 47.75-736.72 ng/mL and peak M1 levels were 75.30-1084.92 ng/mL; in rats, peak tramadol plasma levels were 185.03-455.81 ng/mL and peak M1 levels were 106.74-455.70 ng/mL. Tramadol brain levels were also greatest 10 min after dosing. In mice, peak tramadol brain levels were 226.42-1847.46 ng/g. Peak M1 levels (72.17-572.97 ng/g) occurred 20-60 min after dosing. In rats, peak tramadol brain levels were 258.50-1777.37 ng/g and peak M1 levels were 80.35-289.60 ng/g. In mice, the ratio of tramadol/M1 in plasma was 0.5-1.0 throughout the measurements, whereas the ratio in brain was about 10 at 10 min and about 2 from 20 to 50 min. In rats, the ratio of tramadol/M1 in plasma was 0.5-1.5, whereas the ratio in brain was about 15 at 10 min and about 4-7 thereafter. CONCLUSION In mice and rats, there appears to be preferential brain vs. plasma distribution of tramadol over M1.
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Tao Q, Stone DJ, Borenstein MR, Jean-Bart V, Codd EE, Coogan TP, Desai-Krieger D, Liao S, Raffa RB. Gas chromatographic method using nitrogen-phosphorus detection for the measurement of tramadol and its O-desmethyl metabolite in plasma and brain tissue of mice and rats. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 2001; 763:165-71. [PMID: 11710575 DOI: 10.1016/s0378-4347(01)00388-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A method that allows the measurement of plasma and brain levels of the centrally-acting analgesic tramadol and its major metabolite (O-desmethyl tramadol) in mice and rats was developed using gas chromatography equipped with nitrogen-phosphorus detection (GC-NPD). Plasma samples were extracted with methyl tert.-butyl ether (MTBE) and were injected directly into the GC system. Brain tissue homogenates were precipitated with methanol, the resulting supernatant was dried then acidified with hydrochloric acid. The aqueous solution was washed with MTBE twice, alkalinized, and extracted with MTBE. The MTBE layer was dried, reconstituted and injected into the GC system. The GC assay used a DB-1 capillary column with an oven temperature ramp (135 to 179 degrees C at 4 degrees C/min). Dextromethorphan was used as the internal standard. The calibration curves for tramadol and O-desmethyl tramadol in plasma and brain tissue were linear in the range of 10 to 10000 ng/ml (plasma) and ng/g (brain). Assay accuracy and precision of back calculated standards were within +/- 15%.
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Chang YL, Tao Q, Scheuring C, Ding K, Meksem K, Zhang HB. An integrated map of Arabidopsis thaliana for functional analysis of its genome sequence. Genetics 2001; 159:1231-42. [PMID: 11729165 PMCID: PMC1461882 DOI: 10.1093/genetics/159.3.1231] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The genome of the model plant species Arabidopsis thaliana has recently been sequenced. To accelerate its current genome research, we developed a whole-genome, BAC/BIBAC-based, integrated physical, genetic, and sequence map of the A. thaliana ecotype Columbia. This new map was constructed from the clones of a new plant-transformation-competent BIBAC library and is integrated with the existing sequence map. The clones were restriction fingerprinted by DNA sequencing gel-based electrophoresis, assembled into contigs, and anchored to an existing genetic map. The map consists of 194 BAC/BIBAC contigs, spanning 126 Mb of the 130-Mb Arabidopsis genome. A total of 120 contigs, spanning 114 Mb, were anchored to the chromosomes of Arabidopsis. Accuracy of the integrated map was verified using the existing physical and sequence maps and numerous DNA markers. Integration of the new map with the sequence map has enabled gap closure of the sequence map and will facilitate functional analysis of the genome sequence. The method used here has been demonstrated to be sufficient for whole-genome physical mapping from large-insert random bacterial clones and thus is applicable to rapid development of whole-genome physical maps for other species.
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Mei W, Yang J, Tao Q, Geng X, Rupp RA, Ding X. An interferon regulatory factor-like binding element restricts Xmyf-5 expression in the posterior somites during Xenopus myogenesis. FEBS Lett 2001; 505:47-52. [PMID: 11557040 DOI: 10.1016/s0014-5793(01)02688-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The expression of myf-5, a key component of myogenic regulatory genes, declines progressively in mature somitic cells during vertebrate myogenesis. Little is known about how this down-regulation takes place. Here we provide evidence that an interferon regulatory factor binding element (IRF element) within the Xenopus myf-5 promoter is responsible for the elimination of myf-5 transcription in mature somitic mesoderm of Xenopus embryos. We show that this IRF element mediates the down-regulation of Xmyf-5 transcription in gastrula embryos, and can specifically interact with nuclear proteins of early neurula. Moreover, deletion of this IRF element results in the anterior expansion of reporter gene transcripts within somitic mesoderm in transgenic embryos. Our results, therefore, provide insight into how the negative control of Xmyf-5 expression takes place.
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Tao Q, Chang YL, Wang J, Chen H, Islam-Faridi MN, Scheuring C, Wang B, Stelly DM, Zhang HB. Bacterial artificial chromosome-based physical map of the rice genome constructed by restriction fingerprint analysis. Genetics 2001; 158:1711-24. [PMID: 11514457 PMCID: PMC1461754 DOI: 10.1093/genetics/158.4.1711] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Genome-wide physical mapping with bacteria-based large-insert clones (e.g., BACs, PACs, and PBCs) promises to revolutionize genomics of large, complex genomes. To accelerate rice and other grass species genome research, we developed a genome-wide BAC-based map of the rice genome. The map consists of 298 BAC contigs and covers 419 Mb of the 430-Mb rice genome. Subsequent analysis indicated that the contigs constituting the map are accurate and reliable. Particularly important to proficiency were (1) a high-resolution, high-throughput DNA sequencing gel-based electrophoretic method for BAC fingerprinting, (2) the use of several complementary large-insert BAC libraries, and (3) computer-aided contig assembly. It has been demonstrated that the fingerprinting method is not significantly influenced by repeated sequences, genome size, and genome complexity. Use of several complementary libraries developed with different restriction enzymes minimized the "gaps" in the physical map. In contrast to previous estimates, a clonal coverage of 6.0-8.0 genome equivalents seems to be sufficient for development of a genome-wide physical map of approximately 95% genome coverage. This study indicates that genome-wide BAC-based physical maps can be developed quickly and economically for a variety of plant and animal species by restriction fingerprint analysis via DNA sequencing gel-based electrophoresis.
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Ma W, Feng B, Tao Q. Murine antibody against E2 can capture hepatitis C virus in vitro. Chin Med J (Engl) 2001; 114:860-3. [PMID: 11780368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
OBJECTIVE To find neutralizing antibody candidates against hepatitis C virus (HCV) infection. METHODS We constructed two eukaryotic expression vectors which contained the E1 and E2 gene of HCV, and detected their expression in mammalian cells with transient expression. BALB/c mice were given subculaneous injections of constructed vectors combined with the IL-2 gene intraepidermally and evaluated for induced humoral immune responses by enzyme-linked immunosorbent assay (ELISA). We used an antibody-virus interaction assay to analyze the interaction of the antisera and HCV viral particles in vitro. RESULTS Anti E1 and anti-E2 antisera were obtained from immunized mice. The serum of mice immunized with the E2 gene immunoprecipitated the HCV isolate in source serum and reacted with the isolates unrelated to the original one. CONCLUSIONS Anti-E2 antibody in induced mice can cross-reactively capture HCV particles, highlighting the possibility of generating broadly reactive anti-E2 antibodies.
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Tao Q, Backer MV, Backer JM, Terman BI. Kinase insert domain receptor (KDR) extracellular immunoglobulin-like domains 4-7 contain structural features that block receptor dimerization and vascular endothelial growth factor-induced signaling. J Biol Chem 2001; 276:21916-23. [PMID: 11399777 DOI: 10.1074/jbc.m100763200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The vascular endothelial growth factor (VEGF) receptor tyrosine kinase subtype kinase insert domain receptor (KDR) contains seven extracellular Ig-like domains, of which the three most amino-terminal contain the necessary structural features required for VEGF binding. To clarify the functional role of KDR Ig-like domains 4-7, we compared VEGF-induced signaling in human embryonic kidney and porcine aortic endothelial cells expressing native versus mutant receptor proteins in which Ig-like domains 4-7, 4-6, or 7 had been deleted. Western blotting using an anti-receptor antibody indicated equivalent expression levels for each of the recombinant proteins. As expected, VEGF treatment robustly augmented native receptor autophosphorylation. In contrast, receptor autophosphorylation, as well as downstream signaling events, were VEGF-independent for cells expressing mutant receptors. (125)I-VEGF(165) bound with equal or better affinity to mutant versus native receptor, although the number of radioligand binding sites was significantly reduced because a significant percentage of mutant, but not native, receptors were localized to the cell interior. As was the case for native KDR, (125)I-VEGF(165) binding to the mutant receptors was dependent upon cell surface heparan sulfate proteoglycans, and (125)I-VEGF(121) bound with an affinity equal to that of (125)I-VEGF(165) to the native and mutant receptors. It is concluded that KDR Ig-like domains 4-7 contain structural features that inhibit receptor signaling by a mechanism that is independent of neuropilin-1 and heparan sulfate proteoglycans. We speculate that this provides a cellular mechanism for blocking unwanted signaling events in the absence of VEGF.
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Deng Z, Huang S, Ling P, Yu C, Tao Q, Chen C, Wendell MK, Zhang HB, Gmitter FG. Fine genetic mapping and BAC contig development for the citrus tristeza virus resistance gene locus in Poncirus trifoliata (Raf.). Mol Genet Genomics 2001; 265:739-47. [PMID: 11459195 DOI: 10.1007/s004380100471] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A map-based cloning strategy has been employed to isolate Ctv, a single dominant gene from Poncirus trifoliata that confers resistance to citrus tristeza virus (CTV), the most important viral pathogen of citrus. Cloning of this gene will allow development of commercially acceptable, virus-resistant cultivars. A high-resolution genetic linkage map of the Ctv locus region was developed using a backcross population of 678 individuals. Three DNA markers that were closely linked or co-segregated with Ctv were identified and used to screen BAC libraries derived from an intergeneric hybrid of Poncirus and Citrus. Through chromosome walking and landing, two BAC contigs were developed: one encompassing the Ctv region, and the other spanning the allelic susceptibility gene region. The resistance gene contig consists of 20 BAC clones and is approximately 550 kb in length; the susceptibility gene contig consists of 16 BAC clones and extends about 450 kb. The Ctv locus was localized within a genomic region of approximately 180 kb by genetic mapping of BAC insert ends. The BAC contigs were integrated with the genetic map; variation in the ratio of genetic to physical distance was observed in the vicinity of Ctv. Southern hybridization data indicated that a few copies of NBS-LRR class sequences are distributed at or around the Ctv locus. Efforts are being made to assign the Ctv locus to a smaller genomic fragment whose function can be confirmed through genetic complementation of a CTV susceptible phenotype. These results indicate that map-based gene cloning is feasible in a woody perennial.
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Ju DW, Tao Q, Lou G, Bai M, He L, Yang Y, Cao X. Interleukin 18 transfection enhances antitumor immunity induced by dendritic cell-tumor cell conjugates. Cancer Res 2001; 61:3735-40. [PMID: 11325846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Dendritic cell (DC)-based tumor vaccine represents a promising approach to the immunotherapy of malignant tumors. We prepared a novel type of DC-based vaccine, stable conjugates of DCs and EL4 cells transduced with cDNA of OVA (E.G7). Immunization with DC-E.G7 conjugates led to generation of T helper (Th) 1 cytokine-producing cells, antigen-specific CD8(+) T cells, and strong antitumor immunity that is dependent on both CD4(+) T cells and CD8(+) T cells. To further increase the potency of the vaccine, interleukin 18-transfected DCs were used to prepare the IL18DC-E.G7 conjugates. Immunization with such conjugates significantly increased the production of Th1 cytokine-producing cells and the number of antigen-specific CD8(+) T cells, as well as stronger antitumor immunity. Furthermore, the increased Th1 cytokine production and stronger antitumor effect were not observed in mice depleted of IFN-gamma. These data indicated that DC-tumor cell conjugates are a potent tumor vaccine. Interleukin 18 can be administrated using gene-transfected cells and enhances antitumor immunity, which is mainly mediated by IFN-gamma.
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Kinard TA, Goforth PB, Tao Q, Abood ME, Teague J, Satin LS. Chloride channels regulate HIT cell volume but cannot fully account for swelling-induced insulin secretion. Diabetes 2001; 50:992-1003. [PMID: 11334443 DOI: 10.2337/diabetes.50.5.992] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Insulin-secreting pancreatic islet beta-cells possess anion-permeable Cl- channels (I(Cl,islet)) that are swelling-activated, but the role of these channels in the cells is unclear. The Cl- channel blockers 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) and niflumic acid were evaluated for their ability to inhibit I(Cl,islet) in clonal beta-cells (HIT cells). Both drugs blocked the channel, but the blockade due to niflumic acid was less voltage-dependent than the blockade due to DIDS. HIT cell volume initially increased in hypotonic solution and was followed by a regulatory volume decrease (RVD). The addition of niflumic acid and, to a lesser extent, DIDS to the hypotonic solution potentiated swelling and blocked the RVD. In isotonic solution, niflumic acid produced swelling, suggesting that islet Cl- channels are activated under basal conditions. The channel blockers glyburide, gadolinium, or tetraethylammonium-Cl did not alter hypotonic-induced swelling or volume regulation. The Na/K/2Cl transport blocker furosemide produced cell shrinkage in isotonic solution and blocked cell swelling normally induced by hypotonic solution. Perifused HIT cells secreted insulin when challenged with hypotonic solutions. However, this could not be completely attributed to I(Cl,islet)-mediated depolarization, because secretion persisted even when Cl- channels were fully blocked. To test whether blocker-resistant secretion occurred via a distal pathway, distal secretion was isolated using 50 mmol/l potassium and diazoxide. Under these conditions, glucose-dependent secretion was blunted, but hypotonically induced secretion persisted, even with Cl- channel blockers present. These results suggest that beta-cell swelling stimulates insulin secretion primarily via a distal I(Cl,islet)-independent mechanism, as has been proposed for K(ATP)-independent glucose- and sulfonylurea-stimulated insulin secretion. Reverse transcriptase-polymerase chain reaction of HIT cell mRNA identified a CLC-3 transcript in HIT cells. In other systems, CLC-3 is believed to mediate swelling-induced outwardly rectifying Cl- channels. This suggests that the proximal effects of swelling to regulate cell volume may be mediated by CLC-3 or a closely related Cl- channel.
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Gao J, Tao Q, Ma D. [Prokaryotic expression of hepatitis C virus envelope 1 gene and application of the expressed product]. ZHONGHUA SHI YAN HE LIN CHUANG BING DU XUE ZA ZHI = ZHONGHUA SHIYAN HE LINCHUANG BINGDUXUE ZAZHI = CHINESE JOURNAL OF EXPERIMENTAL AND CLINICAL VIROLOGY 2001; 15:20-3. [PMID: 12526296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
OBJECTIVE To express the HCV E1 gene in E. coli cells and to demonstrate its clinical significance in detection of anti-HCV E1 antibodies. METHODS The expression vector was constructed by ligation of HCV E1 sequence, which was amplified by RT-PCR methods from 50 microliters of HCV RNA positive serum using primers specific to the HCV E1 sequence, to the prokaryotic expression vector PMS-31b transfected POP2136 at 16 degrees C for 16 hours. The recombinant plasmid was screened out and characterized by restriction enzyme analysis. The bacteria containing the recombinant plasmid was induced at 42 degrees C for 4 hours, and the recombinant protein was visualized by SDS-PAGE. The specificity of the recombinant protein was determined by Western blot assay. After purification of the expressed protein, this protein was coated on the plate with the concentration of 2 micrograms/ml in pH 9.6 buffer at 4 degrees C for overnight, and the serum specimen was tested at the dilution of 1:20 by ELISA. RESULTS There were 2 fragments could be seen on the SDS-PAGE after digestion of the RT-PCR product with Sma I. And there emerged one fragment of 356 bp after digesting the recombinant plasmid with Sma I and Xba I. A band of 30,000 could be seen on the SDS-PAGE after the induction of bacteria containing the recombinant plasmid pMS-E1 at 42 degrees C for 4 hours. The Western blot assay showed that the expressed band could react with the anti-HCV positive serum. The ELISA result indicated that there were 28.9% (26/90) anti-HCV positive serum were anti-HCV E1 positive, but 3.9% (3/76) were positive in the anti-HCV negative serum. CONCLUSION The HCV E1 sequence from HCV RNA positive serum has been expressed in E. coli. The expression rate is about 17% of the total protein of the bacteria. This protein possessed good specificity and may be used in the diagnosis of HCV infection.
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