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author:("Wang, chaohu")
1.  Genetic variants in Fas signaling pathway genes and risk of gastric cancer 
Populations in north central China are at high risk for gastric cancers (GC), and altered FAS-mediated cell signaling and/or apoptosis may contribute to this risk. We examined the association of 554 single nucleotide polymorphisms (SNPs) in 53 Fas signaling-related genes using a pathway-based approach in 1758 GC cases (1126 gastric cardia adenocarcinomas (GCA) and 632 gastric noncardia adenocarcinomas (GNCA)), and 2111 controls from a genome-wide association study (GWAS) of GC in ethnic Chinese. SNP associations with risk of overall GC, GCA and GNCA were evaluated using unconditional logistic regressions controlling for age, sex and study. Gene- and pathway-based associations were tested using the adaptive rank-truncated product (ARTP) method. Statistical significance was evaluated empirically by permutation. Significant pathway-based associations were observed for Fas signaling with risk of overall GC (P = 5.5E-04) and GCA (P = 6.3E-03), but not GNCA (P = 8.1E-02). Among examined genes in the Fas signaling pathway, MAP2K4, FAF1, MAPK8, CASP10, CASP8, CFLAR, MAP2K1, CAP8AP2, PAK2 and IKBKB were associated with risk of GC (nominal P < 0.05), and FAF1 and MAPK8 were significantly associated with risk of both GCA and GNCA (nominal P < 0.05). Our examination of genetic variation in the Fas signaling pathway is consistent with an association of altered Fas signaling and/or apoptosis with risk of GC. As one of the first attempts to investigate a pathway-level association, our results suggest that these genes and the Fas signaling pathway warrant further evaluation in relation to GC risk in other populations.
PMCID: PMC3858487  PMID: 23921907
Gastric cancer; gastric cardia; gastric noncardia; Fas signaling; genetic variants; GWAS; single nucleotide polymorphisms; pathway genes
2.  RAD51B Activity and Cell Cycle Regulation in Response to DNA Damage in Breast Cancer Cell Lines 
Common genetic variants mapping to two distinct regions of RAD51B, a paralog of RAD51, have been associated with breast cancer risk in genome-wide association studies (GWAS). RAD51B is a plausible candidate gene because of its established role in the homologous recombination (HR) process. How germline genetic variation in RAD51B confers susceptibility to breast cancer is not well understood. Here, we investigate the molecular function of RAD51B in breast cancer cell lines by knocking down RAD51B expression by small interfering RNA and treating cells with DNA-damaging agents, namely cisplatin, hydroxyurea, or methyl-methanesulfonate. Our results show that RAD51B-depleted breast cancer cells have increased sensitivity to DNA damage, reduced efficiency of HR, and altered cell cycle checkpoint responses. The influence of RAD51B on the cell cycle checkpoint is independent of its role in HR and further studies are required to determine whether these functions can explain the RAD51B breast cancer susceptibility alleles.
PMCID: PMC4213955  PMID: 25368520
RAD51B; breast cancer; DNA damage; homologous recombination
3.  Genetic variants in sex hormone metabolic pathway genes and risk of esophageal squamous cell carcinoma 
Carcinogenesis  2013;34(5):1062-1068.
In China, esophageal cancer is the fourth leading cause of cancer death where essentially all cases are histologically esophageal squamous cell carcinoma (ESCC), in contrast to esophageal adenocarcinoma in the West. Globally, ESCC is 2.4 times more common among men than women and recently it has been suggested that sex hormones may be associated with the risk of ESCC. We examined the association between genetic variants in sex hormone metabolic genes and ESCC risk in a population from north central China with high-incidence rates. A total of 1026 ESCC cases and 1452 controls were genotyped for 797 unique tag single-nucleotide polymorphisms (SNPs) in 51 sex hormone metabolic genes. SNP-, gene- and pathway-based associations with ESCC risk were evaluated using unconditional logistic regression adjusted for age, sex and geographical location and the adaptive rank truncated product (ARTP) method. Statistical significance was determined through use of permutation for pathway- and gene-based associations. No associations were observed for the overall sex hormone metabolic pathway (P = 0.14) or subpathways (androgen synthesis: P = 0.30, estrogen synthesis: P = 0.15 and estrogen removal: P = 0.19) with risk of ESCC. However, six individual genes (including SULT2B1, CYP1B1, CYP3A7, CYP3A5, SHBG and CYP11A1) were significantly associated with ESCC risk (P < 0.05). Our examination of genetic variation in the sex hormone metabolic pathway is consistent with a potential association with risk of ESCC. These positive findings warrant further evaluation in relation to ESCC risk and replication in other populations.
PMCID: PMC3643422  PMID: 23358850
4.  Global Changes in Gene Expression of Barrett's Esophagus Compared to Normal Squamous Esophagus and Gastric Cardia Tissues 
PLoS ONE  2014;9(4):e93219.
Barrett's esophagus (BE) is a metaplastic precursor lesion of esophageal adenocarcinoma (EA), the most rapidly increasing cancer in western societies. While the prevalence of BE is increasing, the vast majority of EA occurs in patients with undiagnosed BE. Thus, we sought to identify genes that are altered in BE compared to the normal mucosa of the esophagus, and which may be potential biomarkers for the development or diagnosis of BE.
We performed gene expression analysis using HG-U133A Affymetrix chips on fresh frozen tissue samples of Barrett's metaplasia and matched normal mucosa from squamous esophagus (NE) and gastric cardia (NC) in 40 BE patients.
Using a cut off of 2-fold and P<1.12E-06 (0.05 with Bonferroni correction), we identified 1324 differentially-expressed genes comparing BE vs NE and 649 differentially-expressed genes comparing BE vs NC. Except for individual genes such as the SOXs and PROM1 that were dysregulated only in BE vs NE, we found a subset of genes (n = 205) whose expression was significantly altered in both BE vs NE and BE vs NC. These genes were overrepresented in different pathways, including TGF-β and Notch.
Our findings provide additional data on the global transcriptome in BE tissues compared to matched NE and NC tissues which should promote further understanding of the functions and regulatory mechanisms of genes involved in BE development, as well as insight into novel genes that may be useful as potential biomarkers for the diagnosis of BE in the future.
PMCID: PMC3979678  PMID: 24714516
5.  Genome-wide association studies of gastric adenocarcinoma and esophageal squamous cell carcinoma identify a shared susceptibility locus in PLCE1 at 10q23 
Nature genetics  2012;44(10):1090-1097.
We conducted a genome-wide association study of gastric cancer (GC) and esophageal squamous cell carcinoma (ESCC) in ethnic Chinese subjects in which we genotyped 551,152 single nucleotide polymorphisms (SNPs). We report a combined analysis of 2,240 GC cases, 2,115 ESCC cases, and 3,302 controls drawn from five studies. In logistic regression models adjusted for age, sex, and study, multiple variants at 10q23 had genome-wide significance for GC and ESCC independently. A notable signal was rs2274223, a nonsynonymous SNP located in PLCE1, for GC (P=8.40×1010; per allele odds ratio (OR) = 1.31) and ESCC (P=3.85×10−9; OR = 1.34). The association with GC differed by anatomic subsite. For tumors located in the cardia the association was stronger (P=4.19 × 10−15; OR= 1.57) and for those located in the noncardia stomach it was absent (P=0.44; OR=1.05). Our findings at 10q23 could provide insight into the high incidence rates of both cancers in China.
PMCID: PMC3513832  PMID: 22960999
6.  Genetic Variants in Epidermal Growth Factor Receptor Pathway Genes and Risk of Esophageal Squamous Cell Carcinoma and Gastric Cancer in a Chinese Population 
PLoS ONE  2013;8(7):e68999.
The epidermal growth factor receptor (EGFR) signaling pathway regulates cell proliferation, differentiation, and survival, and is frequently dysregulated in esophageal and gastric cancers. Few studies have comprehensively examined the association between germline genetic variants in the EGFR pathway and risk of esophageal and gastric cancers. Based on a genome-wide association study in a Han Chinese population, we examined 3443 SNPs in 127 genes in the EGFR pathway for 1942 esophageal squamous cell carcinomas (ESCCs), 1758 gastric cancers (GCs), and 2111 controls. SNP-level analyses were conducted using logistic regression models. We applied the resampling-based adaptive rank truncated product approach to determine the gene- and pathway-level associations. The EGFR pathway was significantly associated with GC risk (P = 2.16×10−3). Gene-level analyses found 10 genes to be associated with GC, including FYN, MAPK8, MAP2K4, GNAI3, MAP2K1, TLN1, PRLR, PLCG2, RPS6KB2, and PIK3R3 (P<0.05). For ESCC, we did not observe a significant pathway-level association (P = 0.72), but gene-level analyses suggested associations between GNAI3, CHRNE, PAK4, WASL, and ITCH, and ESCC (P<0.05). Our data suggest an association between specific genes in the EGFR signaling pathway and risk of GC and ESCC. Further studies are warranted to validate these associations and to investigate underlying mechanisms.
PMCID: PMC3715462  PMID: 23874846
7.  Telomere attrition in cancer cells and telomere length in tumor stroma cells predicts chromosome instability in esophageal squamous cell carcinoma: a genome-wide analysis 
Cancer research  2009;69(4):1604-1614.
Previous studies demonstrated that chromosomal instability was common in esophageal squamous cell carcinoma (ESCC); however, the mechanisms underlying this instability are unknown. Individuals with deficiencies in telomere maintenance are susceptible to enhanced telomere loss during cell proliferation; such deficiencies could result in telomere dysfunction and genomic instability. We investigated the association between genome-wide chromosomal changes in cancer cells and telomere length/attrition in cancer/stroma cells in 47 ESCC patients. Genome-wide detection of loss of heterozygosity (LOH) was performed using the Affymetrix GeneChip SNP arrays. Telomere length was assessed separately for cancer cells, carcinoma-associated fibroblasts (CAFs), infiltrative lymphocytes, and adjacent normal epithelial cells by quantitative fluorescent in situ hybridization using paraffin-embedded sections. Telomere length differed significantly among cell types, such that length in infiltrative lymphocytes > CAFs > cancer cells. Shortened telomeres were observed in cancer cells in 44 out 47 (94%) of the tumors examined. Telomere length in CAFs was significantly associated with chromosomal instability on 4q and 13q, and lymphocytes telomere length was significantly associated with instability on chromosomal arms 15q. While telomere length in cancer cells was not associated with chromosome arm instability, telomere attrition in cancer cells, defined as the telomere length in CAFs minus the telomere length in cancer cells, was significantly associated with chromosomal instability on 13q and 15q. This study provides the evidence that telomere shortening is a common genetic alteration in ESCC, and that chromosome arm instability is related to both telomere attrition in cancer cells and telomere length in tumor stroma cells.
PMCID: PMC3710128  PMID: 19190333
Telomere length; chromosomal instability; esophageal squamous cell carcinoma; telomere dysfunction
8.  Comparison of Global Gene Expression of Gastric Cardia and Noncardia Cancers from a High-Risk Population in China 
PLoS ONE  2013;8(5):e63826.
To profile RNA expression in gastric cancer by anatomic subsites as an initial step in identifying molecular subtypes and providing targets for early detection and therapy.
We performed transcriptome analysis using the Affymetrix GeneChip U133A in gastric cardia adenocarcinomas (n = 62) and gastric noncardia adenocarcinomas (n = 72) and their matched normal tissues from patients in Shanxi Province, and validated selected dysregulated genes with additional RNA studies. Expression of dysregulated genes was also related to survival of cases.
Principal Component Analysis showed that samples clustered by tumor vs. normal, anatomic location, and histopathologic features. Paired t-tests of tumor/normal tissues identified 511 genes whose expression was dysregulated (P<4.7E-07 and at least two-fold difference in magnitude) in cardia or noncardia gastric cancers, including nearly one-half (n = 239, 47%) dysregulated in both cardia and noncardia, one-fourth dysregulated in cardia only (n = 128, 25%), and about one-fourth in noncardia only (n = 144, 28%). Additional RNA studies confirmed profiling results. Expression was associated with case survival for 20 genes in cardia and 36 genes in noncardia gastric cancers.
The dysregulated genes identified here represent a comprehensive starting point for future efforts to understand etiologic heterogeneity, develop diagnostic biomarkers for early detection, and test molecularly-targeted therapies for gastric cancer.
PMCID: PMC3661768  PMID: 23717493
9.  Genotypic variants at 2q33 and risk of esophageal squamous cell carcinoma in China: a meta-analysis of genome-wide association studies 
Abnet, Christian C. | Wang, Zhaoming | Song, Xin | Hu, Nan | Zhou, Fu-You | Freedman, Neal D. | Li, Xue-Min | Yu, Kai | Shu, Xiao-Ou | Yuan, Jian-Min | Zheng, Wei | Dawsey, Sanford M. | Liao, Linda M. | Lee, Maxwell P. | Ding, Ti | Qiao, You-Lin | Gao, Yu-Tang | Koh, Woon-Puay | Xiang, Yong-Bing | Tang, Ze-Zhong | Fan, Jin-Hu | Chung, Charles C. | Wang, Chaoyu | Wheeler, William | Yeager, Meredith | Yuenger, Jeff | Hutchinson, Amy | Jacobs, Kevin B. | Giffen, Carol A. | Burdett, Laurie | Fraumeni, Joseph F. | Tucker, Margaret A. | Chow, Wong-Ho | Zhao, Xue-Ke | Li, Jiang-Man | Li, Ai-Li | Sun, Liang-Dan | Wei, Wu | Li, Ji-Lin | Zhang, Peng | Li, Hong-Lei | Cui, Wen-Yan | Wang, Wei-Peng | Liu, Zhi-Cai | Yang, Xia | Fu, Wen-Jing | Cui, Ji-Li | Lin, Hong-Li | Zhu, Wen-Liang | Liu, Min | Chen, Xi | Chen, Jie | Guo, Li | Han, Jing-Jing | Zhou, Sheng-Li | Huang, Jia | Wu, Yue | Yuan, Chao | Huang, Jing | Ji, Ai-Fang | Kul, Jian-Wei | Fan, Zhong-Min | Wang, Jian-Po | Zhang, Dong-Yun | Zhang, Lian-Qun | Zhang, Wei | Chen, Yuan-Fang | Ren, Jing-Li | Li, Xiu-Min | Dong, Jin-Cheng | Xing, Guo-Lan | Guo, Zhi-Gang | Yang, Jian-Xue | Mao, Yi-Ming | Yuan, Yuan | Guo, Er-Tao | Zhang, Wei | Hou, Zhi-Chao | Liu, Jing | Li, Yan | Tang, Sa | Chang, Jia | Peng, Xiu-Qin | Han, Min | Yin, Wan-Li | Liu, Ya-Li | Hu, Yan-Long | Liu, Yu | Yang, Liu-Qin | Zhu, Fu-Guo | Yang, Xiu-Feng | Feng, Xiao-Shan | Wang, Zhou | Li, Yin | Gao, She-Gan | Liu, Hai-Lin | Yuan, Ling | Jin, Yan | Zhang, Yan-Rui | Sheyhidin, Ilyar | Li, Feng | Chen, Bao-Ping | Ren, Shu-Wei | Liu, Bin | Li, Dan | Zhang, Gao-Fu | Yue, Wen-Bin | Feng, Chang-Wei | Qige, Qirenwang | Zhao, Jian-Ting | Yang, Wen-Jun | Lei, Guang-Yan | Chen, Long-Qi | Li, En-Min | Xu, Li-Yan | Wu, Zhi-Yong | Bao, Zhi-Qin | Chen, Ji-Li | Li, Xian-Chang | Zhuang, Xiang | Zhou, Ying-Fa | Zuo, Xian-Bo | Dong, Zi-Ming | Wang, Lu-Wen | Fan, Xue-Pin | Wang, Jin | Zhou, Qi | Ma, Guo-Shun | Zhang, Qin-Xian | Liu, Hai | Jian, Xin-Ying | Lian, Sin-Yong | Wang, Jin-Sheng | Chang, Fu-Bao | Lu, Chang-Dong | Miao, Jian-Jun | Chen, Zhi-Guo | Wang, Ran | Guo, Ming | Fan, Zeng-Lin | Tao, Ping | Liu, Tai-Jing | Wei, Jin-Chang | Kong, Qing-Peng | Fan, Lei | Wang, Xian-Zeng | Gao, Fu-Sheng | Wang, Tian-Yun | Xie, Dong | Wang, Li | Chen, Shu-Qing | Yang, Wan-Cai | Hong, Jun-Yan | Wang, Liang | Qiu, Song-Liang | Goldstein, Alisa M. | Yuan, Zhi-Qing | Chanock, Stephen J. | Zhang, Xue-Jun | Taylor, Philip R. | Wang, Li-Dong
Human Molecular Genetics  2012;21(9):2132-2141.
Genome-wide association studies have identified susceptibility loci for esophageal squamous cell carcinoma (ESCC). We conducted a meta-analysis of all single-nucleotide polymorphisms (SNPs) that showed nominally significant P-values in two previously published genome-wide scans that included a total of 2961 ESCC cases and 3400 controls. The meta-analysis revealed five SNPs at 2q33 with P< 5 × 10−8, and the strongest signal was rs13016963, with a combined odds ratio (95% confidence interval) of 1.29 (1.19–1.40) and P= 7.63 × 10−10. An imputation analysis of 4304 SNPs at 2q33 suggested a single association signal, and the strongest imputed SNP associations were similar to those from the genotyped SNPs. We conducted an ancestral recombination graph analysis with 53 SNPs to identify one or more haplotypes that harbor the variants directly responsible for the detected association signal. This showed that the five SNPs exist in a single haplotype along with 45 imputed SNPs in strong linkage disequilibrium, and the strongest candidate was rs10201587, one of the genotyped SNPs. Our meta-analysis found genome-wide significant SNPs at 2q33 that map to the CASP8/ALS2CR12/TRAK2 gene region. Variants in CASP8 have been extensively studied across a spectrum of cancers with mixed results. The locus we identified appears to be distinct from the widely studied rs3834129 and rs1045485 SNPs in CASP8. Future studies of esophageal and other cancers should focus on comprehensive sequencing of this 2q33 locus and functional analysis of rs13016963 and rs10201587 and other strongly correlated variants.
PMCID: PMC3315211  PMID: 22323360
10.  A gene expression signature from peripheral whole blood for stage I lung adenocarcinoma 
Affordable early screening in subjects with high risk of lung cancer has great potential to improve survival from this deadly disease. We measured gene expression from lung tissue and peripheral whole blood (PWB) from adenocarcinoma cases and controls to identify dysregulated lung cancer genes that could be tested in blood to improve identification of at-risk patients in the future. Genome-wide mRNA expression analysis was conducted in 153 subjects (73 adenocarcinoma cases, 80 controls) from the Environment And Genetics in Lung cancer Etiology (EAGLE) study using PWB and paired snap-frozen tumor and non-involved lung tissue samples. Analyses were conducted using unpaired t-tests, linear mixed effects and ANOVA models. The area under the receiver operating characteristic curve (AUC) was computed to assess the predictive accuracy of the identified biomarkers. We identified 50 dysregulated genes in stage I adenocarcinoma versus control PWB samples (False Discovery Rate ≤0.1, fold change ≥1.5 or ≤0.66). Among them, eight (TGFBR3, RUNX3, TRGC2, TRGV9, TARP, ACP1, VCAN, and TSTA3) differentiated paired tumor versus non-involved lung tissue samples in stage I cases, suggesting a similar pattern of lung cancer-related changes in PWB and lung tissue. These results were confirmed in two independent gene expression analyses in a blood-based case-control study (n=212) and a tumor-non tumor paired tissue study (n=54). The eight genes discriminated patients with lung cancer from healthy controls with high accuracy (AUC=0.81, 95% CI=0.74–0.87). Our finding suggests the use of gene expression from PWB for the identification of early detection markers of lung cancer in the future.
PMCID: PMC3188352  PMID: 21742797
microarray gene expression; peripheral blood; lung cancer; stage I
11.  Global gene expression profiling and validation in esophageal squamous cell carcinoma (ESCC) and its association with clinical phenotypes 
Esophageal squamous cell carcinoma (ESCC) is an aggressive tumor with poor prognosis. Understanding molecular changes in ESCC will enable identification of molecular subtypes and provide potential targets for early detection and therapy.
Experimental Design
We followed up a previous array study with additional discovery and confirmatory studies in new ESCC cases using alternative methods. We profiled global gene expression for discovery and confirmation, and validated selected dysregulated genes with additional RNA and protein studies.
A total of 159 genes showed differences with extreme statistical significance (P
We identified an expanded panel of genes dysregulated in ESCC and confirmed previously identified differentially-expressed genes. Microarray-based gene expression results were confirmed by RT-PCR and protein expression studies. These dysregulated genes will facilitate molecular categorization of tumor subtypes and identification of their risk factors, and serve as potential targets for early detection, outcome prediction, and therapy.
PMCID: PMC3086948  PMID: 21385931
esophageal squamous cell carcinoma (ESCC); Affymetrix oligomicroarray; RT-PCR; tissue microarray (TMA)
Anticancer research  2011;31(3):945-952.
Several studies have suggested that fascin, cytokeratin 14 and cytokeratin 4 may have significant roles as biomarkers for the progression and survival of esophageal squamous cell carcinoma (ESCC).
This study performed immunohistochemistry in tissue microarrays, profiling premalignant lesions and invasive tumors.
Fascin increased across the following states as follows: normal epithelium (26%) to dysplasia (46%) to ESCC (68%), while CK4 was undetectable in ESCC (0%) compared to normal epithelium (45%) or dysplasia (41%). CK14 was elevated and invariant in expression. In regression analyses, compared to normal epithelium, higher fascin expression was associated with a 36% increased risk of dysplasia (odds ratio=1.36) and a 56% increased risk of invasive ESCC (odds ratio=1.56).
Expression of fascin is up-regulated in the transformation from normal epithelium, through dysplasia, into invasive carcinoma. Expression of CK4, CK14 and fascin did not correlate with patient survival. Fascin has a potential role as an early detection biomarker and CK4 as a tumor marker in ESCC.
PMCID: PMC3236111  PMID: 21498718
Nature genetics  2010;42(9):764-767.
We conducted a genome-wide association study of gastric cancer (GC) and esophageal squamous cell carcinoma (ESCC) in ethnic Chinese subjects in which we genotyped 551,152 single nucleotide polymorphisms (SNPs). We report a combined analysis of 2,240 GC cases, 2,115 ESCC cases, and 3,302 controls drawn from five studies. In logistic regression models adjusted for age, sex, and study, multiple variants at 10q23 had genome-wide significance for GC and ESCC independently. A notable signal was rs2274223, a nonsynonymous SNP located in PLCE1, for GC (P=8.40×10−9; per allele odds ratio (OR) = 1.31) and ESCC (P=3.85×10−9; OR = 1.34). The association with GC differed by anatomic subsite. For tumors located in the cardia the association was stronger (P=4.19 × 10−15; OR= 1.57) and for those located in the noncardia stomach it was absent (P=0.44; OR=1.05). Our findings at 10q23 could provide insight into the high incidence rates of both cancers in China.
PMCID: PMC2947317  PMID: 20729852
BMC Genomics  2010;11:576.
Genomic instability plays an important role in human cancers. We previously characterized genomic instability in esophageal squamous cell carcinomas (ESCC) in terms of loss of heterozygosity (LOH) and copy number (CN) changes in tumors using the Affymetrix GeneChip Human Mapping 500K array in 30 cases from a high-risk region of China. In the current study we focused on copy number neutral (CN = 2) LOH (CNNLOH) and its relation to gene expression in ESCC.
Overall we found that 70% of all LOH observed was CNNLOH. Ninety percent of ESCCs showed CNNLOH (median frequency in cases = 60%) and this was the most common type of LOH in two-thirds of cases. CNNLOH occurred on all 39 autosomal chromosome arms, with highest frequencies on 19p (100%), 5p (96%), 2p (95%), and 20q (95%). In contrast, LOH with CN loss represented 19% of all LOH, occurred in just half of ESCCs (median frequency in cases = 0%), and was most frequent on 3p (56%), 5q (47%), and 21q (41%). LOH with CN gain was 11% of all LOH, occurred in 93% of ESCCs (median frequency in cases = 13%), and was most common on 20p (82%), 8q (74%), and 3q (42%). To examine the effect of genomic instability on gene expression, we evaluated RNA profiles from 17 pairs of matched normal and tumor samples (a subset of the 30 ESCCs) using Affymetrix U133A 2.0 arrays. In CN neutral regions, expression of 168 genes (containing 1976 SNPs) differed significantly in tumors with LOH versus tumors without LOH, including 101 genes that were up-regulated and 67 that were down-regulated.
Our results indicate that CNNLOH has a profound impact on gene expression in ESCC, which in turn may affect tumor development.
PMCID: PMC3091724  PMID: 20955586
Cancer research  2009;69(14):5908-5917.
Genomic instability plays an important role in most human cancers. To characterize genomic instability in esophageal squamous cell carcinoma (ESCC), we examined loss of heterozygosity (LOH), copy number (CN) loss, CN gain, and gene expression using the Affymetrix GeneChip Human Mapping 500K (n=30 cases) and Human U133A (n=17 cases) arrays in ESCC cases from a high-risk region of China. We found that genomic instability measures varied widely among cases and separated them into two groups: a high-frequency instability group (two-thirds of all cases with one or more instability category ≥ 10%) and a low-frequency instability group (one-third of cases with instability < 10%). Genomic instability also varied widely across chromosomal arms, with the highest frequency of LOH on 9p (33% of informative single nucleotide polymorphisms (SNPs)), CN loss on 3p (33%), and CN gain on 3q (48%). Twenty-two LOH regions were identified: four on 9p, seven on 9q, four on 13q, two on 17p, and five on 17q. Three CN loss regions – 3p12.3, 4p15.1, and 9p21.3 – were detected. Twelve CN gain regions were found, including six on 3q, one on 7q, four on 8q, and one on 11q. One of the most gene-rich of these CN gain regions was 11q13.1-13.4, where 26 genes also had RNA expression data available. CN gain was significantly correlated with increased RNA expression in over 80% of these genes. Our findings demonstrate the potential utility of combining CN analysis and gene expression data to identify genes involved in esophageal carcinogenesis.
PMCID: PMC2734334  PMID: 19584285
esophageal cancer; LOH; copy number alteration; 500K SNP array
PLoS ONE  2010;5(2):e9355.
Recent studies have shown a genetic influence on gene expression variation, chromatin, and DNA methylation. However, the effects of genetic background and tissue types on DNA methylation at the genome-wide level have not been characterized extensively. To study the effect of genetic background and tissue types on global DNA methylation, we performed DNA methylation analysis using the Affymetrix 500K SNP array on tumor, adjacent normal tissue, and blood DNA from 30 patients with esophageal squamous cell carcinoma (ESCC). The use of multiple tissues from 30 individuals allowed us to evaluate variation of DNA methylation states across tissues and individuals. Our results demonstrate that blood and esophageal tissues shared similar DNA methylation patterns within the same individual, suggesting an influence of genetic background on DNA methylation. Furthermore, we showed that tissue types are important contributors of DNA methylation states.
PMCID: PMC2826396  PMID: 20186319
In a previous pilot case-control study of individuals diagnosed with esophageal squamous cell carcinoma (ESCC) and matched controls from a high-risk area in China, we identified 38 single nucleotide polymorphisms (SNPs) associated with ESCC located in or near one of 33 genes. In the present study, we attempted to replicate the results of these 38 gene-related SNPs in a new sample of 300 ESCC cases and 300 matched controls from the same study conducted in Shanxi Province, China. Among 36 evaluable SNPs, four were significant in one or more analyses, including SNPs located in EPHB1, PGLYRP2, PIK3C3, and SLC9A9, although the odds ratios (ORs) for these genotypes were modest. Associations were found with EPHB1/rs1515366 (OR 0.92, 95% CI 0.86-0.99; p = 0.019), PIK3C3/rs52911 (OR 0.93, 95% CI 0.88-0.99; p = 0.02), and PGLYRP2/rs959117 (OR 0.93, 95% CI, 0.86-1.01; p = 0.061) in general linear models (additive mode); and the genotype distribution differed between cases and controls for SLC9A9/rs956062 (p = 0.024). To examine these four genes in more detail, 40 HapMap-based tag SNPs from these four genes were evaluated in the same subjects, and seven additional SNPs associated with ESCC were identified. Further confirmation of these findings in other populations and other studies are needed to determine if the signals from these SNPs are indirectly associated due to linkage disequilibrium, or are directly related to biologic function and the development of ESCC.
PMCID: PMC2552411  PMID: 18649358
Esophageal cancer; Replication study; SNP
Molecular events associated with the initiation and progression of esophageal squamous cell carcinoma (ESCC) remain poorly understood, but likely hold the key to effective early detection approaches for this almost invariably fatal cancer. CDC25B and LAMC2 are two promising early detection candidates emerging from new molecular studies of ESCC. To further elucidate the role of these two genes in esophageal carcinogenesis, we performed a series of studies to: (i) confirm RNA over-expression; (ii) establish the prevalence of protein over-expression; (iii) relate protein over-expression to survival; and (iv) explore their potential as early detection biomarkers. Results of these studies indicated that CDC25B mRNA was over-expressed (≥2-fold over-expression in tumor compared to normal) in 64% of the 73 ESCC cases evaluated, while LAMC2 mRNA was over-expressed in 89% of cases. CDC25B protein expression was categorized as positive in 59% (144/243) of ESCC cases on a tumor tissue microarray, and non-negative LAMC2 patterns of protein expression were observed in 82% (225/275) of cases. Multivariate-adjusted proportional hazard regression models showed no association between CDC25B protein expression score and risk of death (Hazard Ratio [HR] for each unit increase in expression score = 1.00, P=0.90), however, several of the LAMC2 protein expression patterns strongly predicted survival. Using the cytoplasmic pattern as the reference (the pattern with the lowest mortality), cases with a diffuse pattern had a 254% increased risk of death (HR=3.52, P=0.007), cases with no LAMC2 expression had a 169% increased risk of death (HR=2.69, P=0.009), and cases with a peripheral pattern had a 130% greater risk of death (HR=2.30, P=0.02). CDC25B protein expression scores in subjects with esophageal biopsies diagnosed as normal (n=35), dysplastic (n=23), or ESCC (n=32) increased significantly with morphologic progression. For LAMC2, all normal and dysplastic patients had a continuous pattern of protein expression, while all ESCCs showed alternative, non-continuous patterns. This series of studies showed that both CDC25B and LAMC2 over-express RNA and protein in a significant majority of ESCC cases. The strong relation of LAMC2 pattern of protein expression to survival suggests a role in prognosis, while CDC25B’s association with morphologic progression indicates a potential role as an early detection marker.
PMCID: PMC2729558  PMID: 18559558
esophageal cancer; quantitative RT-PCR; tissue microarray; survival; early detection; CDC25B; LAMC2
PLoS Genetics  2007;3(5):e81.
Several recent studies have shown a genetic influence on gene expression variation, including variation between the two chromosomes within an individual and variation between individuals at the population level. We hypothesized that genetic inheritance may also affect variation in chromatin states. To test this hypothesis, we analyzed chromatin states in 12 lymphoblastoid cells derived from two Centre d'Etude du Polymorphisme Humain families using an allele-specific chromatin immunoprecipitation (ChIP-on-chip) assay with Affymetrix 10K SNP chip. We performed the allele-specific ChIP-on-chip assays for the 12 lymphoblastoid cells using antibodies targeting at RNA polymerase II and five post-translation modified forms of the histone H3 protein. The use of multiple cell lines from the Centre d'Etude du Polymorphisme Humain families allowed us to evaluate variation of chromatin states across pedigrees. These studies demonstrated that chromatin state clustered by family. Our results support the idea that genetic inheritance can determine the epigenetic state of the chromatin as shown previously in model organisms. To our knowledge, this is the first demonstration in humans that genetics may be an important factor that influences global chromatin state mediated by histone modification, the hallmark of the epigenetic phenomena.
Author Summary
Human health and disease are determined by an interaction between genetic background and environmental exposures. Both normal development and disease are mediated by epigenetic regulation of gene expression. The epigenetic regulation causes heritable changes in gene expression, which is not associated with DNA sequence changes. Instead, it is mediated by chemical modification of DNA such as DNA methylation or by protein modifications such as histone acetylation and methylation. Although much has been known about epigenetic inheritance during development, little is known about the influence of the genetic background on epigenetic processes such as histone modifications. In this report the authors studied five histone modifications on a genome-wide level in cells from different families. Global epigenetic states, as measured by these histone modifications, showed a similar pattern for cells derived from the same family. This study demonstrates that genetic inheritance may be an important factor influencing global chromatin states mediated by histone modifications in humans. These observations illustrate the importance of integrating genetic and epigenetic information into studies of human health and complex diseases.
PMCID: PMC1868950  PMID: 17511522
BMC Genomics  2006;7:299.
Esophageal squamous cell carcinoma (ESCC) is a common malignancy worldwide. Comprehensive genomic characterization of ESCC will further our understanding of the carcinogenesis process in this disease.
Genome-wide detection of chromosomal changes was performed using the Affymetrix GeneChip 10 K single nucleotide polymorphism (SNP) array, including loss of heterozygosity (LOH) and copy number alterations (CNA), for 26 pairs of matched germ-line and micro-dissected tumor DNA samples. LOH regions were identified by two methods – using Affymetrix's genotype call software and using Affymetrix's copy number alteration tool (CNAT) software – and both approaches yielded similar results. Non-random LOH regions were found on 10 chromosomal arms (in decreasing order of frequency: 17p, 9p, 9q, 13q, 17q, 4q, 4p, 3p, 15q, and 5q), including 20 novel LOH regions (10 kb to 4.26 Mb). Fifteen CNA-loss regions (200 kb to 4.3 Mb) and 36 CNA-gain regions (200 kb to 9.3 Mb) were also identified.
These studies demonstrate that the Affymetrix 10 K SNP chip is a valid platform to integrate analyses of LOH and CNA. The comprehensive knowledge gained from this analysis will enable improved strategies to prevent, diagnose, and treat ESCC.
PMCID: PMC1687196  PMID: 17134496
BMC Cancer  2006;6:33.
Esophageal squamous cell carcinoma (ESCC) is one of the most malignant tumors and typically presents at an advanced and rapidly fatal stage. To better understand the role of genetics in the etiology and prevention of ESCC and to identify potential susceptibility genes as well as early detection markers, we previously compared tumor and matched normal tissues from ESCC patients from a high-risk area of China using cDNA expression microarrays and identified 41 differentially-expressed genes (13 over-expressed and 28 under-expressed).
In the current study, we validated and quantitated differential mRNA expression in a sample of nine of these 41 genes, including four that were over-expressed (SPARC, FADD, Fascin, COL7A1), and five that were under-expressed (CK4, TGM3, ECM1, PPL, EVPL), in 75 new ESCC patients using quantitative Real-time RT-PCR and the 2-ΔΔCT method to examine both tumor and matched normal tissue. In addition, we examined expression patterns for these genes by selected demographic and clinical characteristics.
Four previously over-expressed (tumor ≥2-fold normal) genes were all increased in the majority of new ESCC patients: SPARC was increased in 71% of patients, Fascin in 70%, FADD in 63%, and COL7A1 in 57%. Five previously under-expressed (tumor ≤0.5-fold normal) genes similarly showed decreased mRNA expression in two-thirds or more of patients: CK4 was decreased in 83% of patients, TGM3 in 77%, ECM1 in 73%, and PPL and EVPL in 67% each. In subset analyses, associations with age (for COL7A1), family history (for PPL and ECM1), and alcohol use (for SPARC and Fascin) were also noted.
These data indicate that these nine genes have consistent differential mRNA expression, validating results of our previous cDNA array results, and affirming their potential role in the early detection of ESCC.
PMCID: PMC1386690

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