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author:("Do, lieu")
1.  Methylation of the RARB Gene Increases Prostate Cancer Risk in Black Americans 
The Journal of urology  2013;190(1):317-324.
Gene promoter hypermethylation may be useful as a biomarker for cancer risk in histopathologically benign prostate specimens.
Materials and Methods
We performed a nested case-control study of gene promoter methylation status for 5 genes (APC, RARB, CCND2, RASSF1 and MGMT) measured in benign biopsy specimens from 511 prostate cancer case-control pairs. We estimated the overall and race stratified risk of subsequent prostate cancer associated with methylation status.
On race stratified analysis RARB methylation was associated with a higher cancer risk in black American men (OR 2.18, 95% CI 1.39–3.44). APC methylation was associated with an increased risk of high grade tumors (OR 2.43, 95% CI 1.20–4.90), which was higher in black than in white men (OR 3.21 vs 2.04). In cases RARB and APC gene methylation in benign prostate samples persisted in matched malignant specimens. In black cases the combined risk associated with RARB and APC methylation (OR 3.04, 95% CI 1.44–6.42) was greater than the individual risk of each gene and significantly different from that in white cases (OR 1.14, 95% CI 0.56–2.30).
RARB gene methylation in histopathologically benign prostate samples was associated with a statistically significant increased risk of subsequent prostate cancer in black men. Methylation data on additional genes may improve risk stratification and clinical decision making algorithms for cancer screening and diagnosis.
PMCID: PMC3779133  PMID: 23376149
prostate; prostatic neoplasms; risk; DNA methylation; African Americans
2.  LocTree3 prediction of localization 
Nucleic Acids Research  2014;42(Web Server issue):W350-W355.
The prediction of protein sub-cellular localization is an important step toward elucidating protein function. For each query protein sequence, LocTree2 applies machine learning (profile kernel SVM) to predict the native sub-cellular localization in 18 classes for eukaryotes, in six for bacteria and in three for archaea. The method outputs a score that reflects the reliability of each prediction. LocTree2 has performed on par with or better than any other state-of-the-art method. Here, we report the availability of LocTree3 as a public web server. The server includes the machine learning-based LocTree2 and improves over it through the addition of homology-based inference. Assessed on sequence-unique data, LocTree3 reached an 18-state accuracy Q18 = 80 ± 3% for eukaryotes and a six-state accuracy Q6 = 89 ± 4% for bacteria. The server accepts submissions ranging from single protein sequences to entire proteomes. Response time of the unloaded server is about 90 s for a 300-residue eukaryotic protein and a few hours for an entire eukaryotic proteome not considering the generation of the alignments. For over 1000 entirely sequenced organisms, the predictions are directly available as downloads. The web server is available at
PMCID: PMC4086075  PMID: 24848019
3.  Increased methylation of lung cancer-associated genes in sputum DNA of former smokers with chronic mucous hypersecretion 
Respiratory Research  2014;15(1):2.
Chronic mucous hypersecretion (CMH) contributes to COPD exacerbations and increased risk for lung cancer. Because methylation of gene promoters in sputum has been shown to be associated with lung cancer risk, we tested whether such methylation was more common in persons with CMH.
Eleven genes commonly silenced by promoter methylation in lung cancer and associated with cancer risk were selected. Methylation specific PCR (MSP) was used to profile the sputum of 900 individuals in the Lovelace Smokers Cohort (LSC). Replication was performed in 490 individuals from the Pittsburgh Lung Screening Study (PLuSS).
CMH was significantly associated with an overall increased number of methylated genes, with SULF2 methylation demonstrating the most consistent association. The association between SULF2 methylation and CMH was significantly increased in males but not in females both in the LSC and PLuSS (OR = 2.72, 95% CI = 1.51-4.91, p = 0.001 and OR = 2.97, 95% CI = 1.48-5.95, p = 0.002, respectively). Further, the association between methylation and CMH was more pronounced among 139 male former smokers with persistent CMH compared to current smokers (SULF2; OR = 3.65, 95% CI = 1.59-8.37, p = 0.002).
These findings demonstrate that especially male former smokers with persistent CMH have markedly increased promoter methylation of lung cancer risk genes and potentially could be at increased risk for lung cancer.
PMCID: PMC3893562  PMID: 24405663
Methylation of gene promoters; Persistent cough and phlegm; Sputum DNA; Former smoker; Lung cancer genes
4.  Defining a Gene Promoter Methylation Signature in Sputum for Lung Cancer Risk Assessment 
To evaluate the methylation state of 31 genes in sputum as biomarkers in an expanded nested, case-control study from the Colorado Cohort and to assess the replication of results from the most promising genes in an independent case-control study of asymptomatic Stage I lung cancer patients from New Mexico.
Experimental Design
Cases and controls from Colorado and New Mexico were interrogated for methylation of up to 31 genes using nested, methylation specific PCR. Individual genes and methylation indices were used to assess the association between methylation and lung cancer with logistic regression modeling.
Seventeen genes with odds ratios of 1.4 – 3.6 were identified and selected for replication in the New Mexico study. Overall, the direction of effects seen in New Mexico was similar to Colorado with the largest increase in case discrimination (odds ratios, 3.2 – 4.2) seen for the PAX5α, GATA5, and SULF2 genes. ROC curves generated from seven gene panels from Colorado and New Mexico studies showed prediction accuracy of 71% and 77%, respectively. A 22-fold increase in lung cancer risk was seen for a subset of New Mexico cases with five or more genes methylated. Sequence variants associated with lung cancer did not improve the accuracy of this gene methylation panel.
These studies have identified and replicated a panel of methylated genes whose integration with other promising biomarkers could initially identify the highest risk smokers for computed tomography screening for early detection of lung cancer.
PMCID: PMC3483793  PMID: 22510351
gene methylation; sputum; lung cancer; biomarker
5.  EMT and stem cell-like properties associated with miR-205 and miR-200 epigenetic silencing are early manifestations during carcinogen-induced transformation of human lung epithelial cells 
Cancer research  2011;71(8):3087-3097.
Epithelial mesenchymal transition (EMT) is strongly associated with cancer progression, but its potential role during premalignant development has not been studied. Here we show that a four-week exposure of immortalized human bronchial epithelial cells (HBECs) to tobacco carcinogens can induce a persistent, irreversible, and multifaceted dedifferentiation program marked by EMT and the emergence of stem cell-like properties. EMT induction was epigenetically driven, initially by chromatin remodeling through H3K27me3 enrichment and later by ensuing DNA methylation to sustain silencing of tumor suppressive microRNAs miR-200b, miR-200c, and miR-205, which were implicated in the dedifferentiation program in HBECs and also in primary lung tumors. Carcinogen-treated HBECs acquired stem-like features characterized by their ability to form spheroids with branching tubules and enrichment of the CD44high/CD24low, CD133, and ALDH1 stem cell-like markers. miRNA overexpression studies indicated that regulation of the EMT, stem-like, and transformed phenotypes in HBECs were distinct events. Our findings extend present concepts of how EMT participates in cancer pathophysiology by showing that EMT induction can participate in cancer initiation to promote the clonal expansion of premalignant lung epithelial cells.
PMCID: PMC3078195  PMID: 21363915
methylation; miRNA; EMT; stem cells; transformation
6.  The A/G Allele of Rs16906252 Predicts for MGMT Methylation and Is Selectively Silenced in Premalignant Lesions from Smokers and in Lung Adenocarcinomas 
To address the association between sequence variants within the MGMT promoter-enhancer region and methylation of MGMT in premalignant lesions from smokers and lung adenocarcinomas, their biological effects on gene regulation, and targeting MGMT for therapy.
Experimental Design
SNPs identified through sequencing a 1.9kb fragment 5' of MGMT were examined in relation to MGMT methylation in 169 lung adenocarcinomas and 1731 sputum samples from smokers. The effect of promoter haplotypes on MGMT expression was tested using a luciferase reporter assay and cDNA expression analysis along with allele-specific sequencing for methylation. The response of MGMT methylated lung cancer cell lines to the alkylating agent temozolomide was assessed.
The A allele of rs16906252 and the haplotype containing this SNP were strongly associated with increased risk for MGMT methylation in adenocarcinomas (ORs ≥ 94). This association was observed to a lesser extent in sputum samples in both smoker cohorts. The A allele was selectively methylated in primary lung tumors and cell lines heterozygous for rs16906252. With the most common haplotype as the reference, a 20–41% reduction in promoter activity was seen for the haplotype carrying the A allele that correlated with lower MGMT expression. The sensitivity of lung cancer cell lines to temozolamide was strongly correlated with levels of MGMT methylation and expression.
These studies provide strong evidence that the A allele of a MGMT promoter-enhancer SNP is a key determinant for MGMT methylation in lung carcinogenesis. Moreover, temozolamide treatment may benefit a subset of lung cancer patients methylated for MGMT.
PMCID: PMC3070839  PMID: 21355081
MGMT; allele specific methylation; single nucleotide polymorphism; sputum; lung cancer
7.  Re-expression of CXCL14, a common target for epigenetic silencing in lung cancer, induces tumor necrosis 
Oncogene  2010;29(37):5159-5170.
Chemokines are important regulators of directional cell migration and tumor metastasis. A genome-wide transcriptome array designed to uncover novel genes silenced by methylation in lung cancer identified the CXC-subfamily of chemokines. Expression of eleven of the sixteen known human CXC-chemokines was increased in lung adenocarcinoma cell lines after treatment with 5-aza-2deoxycytidine (DAC). Tumor-specific methylation leading to silencing of CXCL5, 12 and 14 was found in over 75% of primary lung adenocarcinomas and DAC treatment restored expression of each silenced gene. Forced expression of CXCL14 in H23 cells where this gene is silenced by methylation increased cell death in vitro and dramatically reduced in vivo growth of lung tumor xenografts through necrosis of up to 90% of the tumor mass. CXCL14 re-expression had a profound effect on the genome altering the transcription of over 1,000 genes, including increased expression of 30 cell cycle inhibitor and pro-apoptosis genes. In addition, CXCL14 methylation in sputum from asymptomatic early stage lung cancer cases was associated with a 2.9-fold elevated risk for this disease compared to controls, substantiating its potential as a biomarker for early detection of lung cancer. Together these findings identify CXCL14 as an important tumor suppressor gene epigenetically silenced during lung carcinogenesis.
PMCID: PMC2940978  PMID: 20562917
CXCL14; Chemokines; lung cancer; DNA methylation; CXCL5; CXCL12
8.  Rosiglitazone prevents the progression of preinvasive lung cancer in a murine model 
Carcinogenesis  2009;30(12):2095-2099.
There is a critical need to identify efficacious chemopreventive agents for lung cancer that can be taken chronically with no side effects and whose mechanisms of action do not involve genotoxicity that could drive, rather than impede, cancer progression. We evaluated the ability of a chemopreventive cocktail that included selenium (antioxidant), rosiglitazone (peroxisome proliferator-activated receptor gamma agonist), sodium phenylbutyrate or valproic acid (histone deacetylase inhibitors) and hydralazine (cytosine-demethylating agent) to prevent the progression of lung cancer in A/J mice treated with NNK. Agents were administered alone or in various combinations. Effects of the chemopreventive agents were quantified based on the proportion of hyperplasias and adenomas within the mouse lung. Significant effects on tumor progression were seen in all treatment groups that included rosiglitazone as reflected by a 47–57% increase in number of hyperplasias and a 10–30% decrease in adenomas. Cell proliferation was also reduced in these treatment groups by ∼40%. Interestingly, while treatment with rosiglitazone alone did not significantly affect lesion size, striking effects were seen in the combination therapy group that included sodium phenylbutyrate, with the volume of hyperplasias and adenomas decreasing by 40 and 77%, respectively. These studies demonstrate for the first time that chronic in vivo administration of rosiglitazone, used in the management of diabetes mellitus, can significantly block the progression of premalignant lung cancer in the A/J mouse model.
PMCID: PMC2792320  PMID: 19861651
9.  Dual promoter regulation of death-associated protein kinase gene leads to differentially silenced transcripts by methylation in cancer 
Carcinogenesis  2009;30(12):2023-2030.
Death-associated protein kinase (DAPK), a mediator of apoptotic systems, is silenced by promoter hypermethylation in lung and breast tumors. This gene has a CpG island extending 2500 bp from the translational start site; however, studies characterizing its transcriptional regulation have not been conducted. Two transcripts for DAPK were identified that code for a single protein, while being regulated by two promoters. The previously identified DAPK transcript designated as exon 1 transcript was expressed at levels 3-fold greater than the alternate exon 1b transcript. Deletion constructs of promoter 1 identified a 332 bp region containing a functional CP2-binding site important for expression of the exon 1 transcript. While moderate reporter activity was seen in promoter 2, the region comprising intron 1 and containing a HNF3B-binding site sustained expression of the alternate transcript. Sequencing the DAPK CpG island in tumor cell lines revealed dense, but heterogenous methylation of CpGs that blocked access of the CP2 and HNF3B proteins that in turn, was associated with loss of transcription that was restored by treatment with 5-aza-2′-deoxycytidine. Prevalences were similar for methylation of promoter 1 and 2 and intron 1 in lung tumors, but significantly greater in promoter 2 and intron 1 in breast tumors, indicative of tissue-specific differences in silencing these two transcripts. These studies show for the first time dual promoter regulation of DAPK, a tumor suppressor gene silenced in many cancers, and substantiate the importance of screening for silencing of both transcripts in tumors.
PMCID: PMC2792322  PMID: 19917631
10.  Double-strand break damage and associated DNA repair genes predispose smokers to gene methylation 
Cancer research  2008;68(8):3049-3056.
Gene promoter hypermethylation in sputum is a promising biomarker for predicting lung cancer. Identifying factors that predispose smokers to methylation of multiple gene promoters in the lung could impact strategies for early detection and chemoprevention. This study evaluated the hypothesis that double-strand break repair capacity and sequence variation in genes in this pathway are associated with a high methylation index in a cohort of current and former cancer-free smokers. A 50% reduction in the mean level of double-strand break repair capacity was seen in lymphocytes from smokers with a high methylation index, defined as ≥ 3 of 8 genes methylated in sputum, compared to smokers with no genes methylated. The classification accuracy for predicting risk for methylation was 88%. Single nucleotide polymorphisms within the MRE11A, CHEK2, XRCC3, DNA-Pkc, and NBN DNA repair genes were highly associated with the methylation index. A 14.5-fold increased odds for high methylation was seen for persons with ≥ 7 risk alleles of these genes. Promoter activity of the MRE11A gene that plays a critical role in recognition of DNA damage and activation of ATM was reduced in persons with the risk allele. Collectively, ours is the first population-based study to identify double-strand break DNA repair capacity and specific genes within this pathway as critical determinants for gene methylation in sputum, that is, in turn, associated with elevated risk for lung cancer.
PMCID: PMC2483467  PMID: 18413776
promoter methylation; DNA double strand break; single nucleotide polymorphism; DNA repair capacity; association study

Results 1-10 (10)