Background

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).

Methods

This study performed immunohistochemistry in tissue microarrays, profiling premalignant lesions and invasive tumors.

Results

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).

Conclusions

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.

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.

Background

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.

Results

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.

Conclusion

Our results indicate that CNNLOH has a profound impact on gene expression in ESCC, which in turn may affect tumor development.

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.

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.

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.

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.

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.

Background

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.

Results

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.

Conclusion

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.

Background

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).

Methods

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.

Results

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.

Conclusion

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.