Xingying Guan

CpG island methylation status of miRNAs in esophageal squamous cell carcinoma.

Previous studies on esophageal squamous cell carcinoma (ESCC) indicated that it contains much dysregulation of microRNAs (miRNAs). DNA hypermethylation in the miRNA 5′ regulatory region is a mechanism that can account for the downregulation of miRNA in tumors (Esteller, N Engl J Med 2008;358:1148–59). Among those dysregulated miRNAs, miR‐203, miR‐34b/c, miR‐424 and miR‐129‐2 are embedded in CpG islands, as is the promoter of miR‐34a. We investigated their methylation status in ESCC by bisulfite sequencing PCR (BSP) and methylation specific PCR (MSP). The methylation frequency of miR‐203 and miR‐424 is the same in carcinoma and in the corresponding non‐tumor tissues. The methylation ratio of miR‐34a, miR‐34b/c and miR‐129‐2 is 66.7% (36/54), 40.7% (22/54) and 96.3% (52/54), respectively in ESCC, which are significantly higher than that in the corresponding non‐tumor tissues(p < 0.01). Quantitative RT‐PCR analysis in clinical samples suggested that CpG island methylation is significantly correlated with their low expression in ESCC, 5‐aza‐2′‐deoxycytidine (DAC) treatment partly recovered their expression in EC9706 cell line. We conclude that CpG island methylation of miR‐34a, miR‐34b/c and miR‐129‐2 are frequent events and important mechanism for their low expression in ESCC. DNA methylation changes have been reported to occur early in carcinogenesis and are potentially good early indicators of carcinoma (Laird, Nat Rev Cancer 2003;3:253–66). The high methylation ratio of miR‐129‐2 indicated its potential as a methylation biomarker in early diagnosis of ESCC.

A functional variation in pre-microRNA-196a is associated with susceptibility of esophageal squamous cell carcinoma risk in Chinese Han

MicroRNAs (miRNAs) are small, non-protein-coding RNAs that function as tumour suppressors or oncogenes. A single nucleotide change in the sequence of pre-miRNA can affect miRNA expression, so single-nucleotide polymorphisms (SNPs) in pre-miRNA may be biomarkers for biomedical applications. In this study, we performed a genetic association study between the SNP (rs11614913) in pre-miRNA-196a and esophageal squamous cell carcinoma (ESCC) susceptibility in a case–control study. We found that the homozygote CC of this SNP increased the risk of ESCC compared with the homozygote TT and the risk was more evident among smokers than non-smokers. Therefore, this functional SNP may be a biomarker for ESCC outcome.

A novel long noncoding RNA linc00460 up-regulated by CBP/P300 promotes carcinogenesis in esophageal squamous cell carcinoma

Esophageal cancer is one of the leading causes of cancer-related mortality because of poor prognosis. Long noncoding RNAs (lncRNAs) have been gradually demonstrated to play critical roles in cancer development. We identified a novel long noncoding RNA named linc00460 by microarray analysis using esophageal squamous cell carcinoma (ESCC) clinical samples, which has not been studied before. Our research indicated that linc00460 was overexpressed in the majority of tumor tissues and ESCC cell lines. Linc00460 expression was positively correlated with ESCC TNM stage, lymph node metastasis, and predicted poor prognosis. In vitro experiments showed that linc00460 depletion suppressed ESCC cell growth through regulating cell proliferation and cell cycle; in additional, linc00460 depletion accelerated ESCC cell apoptosis. We further revealed that linc00460 overexpression was manipulated by transcriptional co-activator CBP/P300 through histone acetylation. Given the high expression and important biological functions of linc00460, we suggest that linc00460 works as an oncogene and might be a valuable prognostic biomarker for ESCC diagnosis and treatment.

Up-regulation of lncRNA CASC9 promotes esophageal squamous cell carcinoma growth by negatively regulating PDCD4 expression through EZH2

BackgroundAbnormal expression of numerous long non-coding RNAs (lncRNAs) has been reported in esophageal squamous cell carcinoma (ESCC) recently, but the great majority of their roles and mechanisms remain largely unclear. We aim to identify the critical ESCC-associated lncRNAs and elucidate the functions and mechanisms in detail.MethodsMicroarrays were used to analyze the differentially expressed lncRNAs in ESCC tissues. qRT-PCR was used to verify the result of microarrays. The effects of the most up-regulated lncRNA, cancer susceptibility candidate 9(CASC9), on cell growth, proliferation and cell cycle were investigated by in vivo and in vitro assays. Microarrays and recovery tests were used to discover the regulatory targets of CASC9. RNA FISH and subcellular fractionation assays were used to detect the subcellular location of CASC9. Finally, the mechanism of CASC9 regulating PDCD4 was explored by RIP, RNA-protein pull down and ChIP assays.ResultsESCC tissue microarrays showed that CASC9 was the most up-regulated lncRNA. qRT-PCR analysis indicated that CASC9 expression was positively associated with tumor size and TNM stage, and predicted poor overall survival of ESCC patients. Knockdown of CASC9 inhibited ESCC cell growth in vitro and tumorigenesis in nude mice. Furthermore interfering CASC9 decreased cell proliferation and blocked cell cycle G1/S transition. CASC9-associated microarrays indicated that PDCD4 might be the target of CASC9. Consistent with this, PDCD4 expression was negatively associated with CASC9 expression in ESCC tissues and predicted good prognosis. Manipulating CASC9 expression in ESCC cells altered both PDCD4 mRNA and protein levels and cell cycle arrest caused by CASC9 knockdown could be rescued by suppressing PDCD4 expression. CASC9 located both in the nucleus and cytoplasm. Mechanistically, enhancer of zeste homolog2 (EZH2) could bind to both CASC9 and PDCD4 promoter region. Interfering CASC9 reduced the enrichment of EZH2 and H3K27me3 in the PDCD4 promoter region.ConclusionsOur study firstly demonstrates that lncRNA CASC9 functions as an oncogene by negatively regulating PDCD4 expression through recruiting EZH2 and subsequently altering H3K27me3 level. Our study implicates lncRNA CASC9 as a valuable biomarker for ESCC diagnosis and prognosis.

EGF-induced C/EBPβ participates in EMT by decreasing the expression of miR-203 in esophageal squamous cell carcinoma cells

ABSTRACT Epithelial–mesenchymal transition (EMT) is a developmental program that is associated with esophageal squamous cell carcinoma (ESCC) progression and metastasis. Recently, C/EBP&bgr; has been reported to be an EMT inducer in cancer. However, the detailed molecular mechanisms remain unclear. Here, we report for the first time, that the truncated CCAAT-enhancer-binding protein &bgr; (C/EBP&bgr;) LIP isoform is abnormally overexpressed and correlated with cancer metastasis in clinical specimens of human ESCC. Furthermore, we demonstrate that C/EBP&bgr; LIP mediates epithelial growth factor (EGF)-induced EMT and increases migration and invasion of esophageal cancer cells in a manner that is dependent on miR-203 inactivation. Finally, we identified miR-203 as a direct target of C/EBP&bgr; LIP. Disruption of C/EBP&bgr; LIP attenuated the EGF-mediated decrease in miR-203, whereas overexpression of C/EBP&bgr; LIP alone markedly suppressed miR-203. In addition, we demonstrated that C/EBP&bgr; LIP inhibited miR-203 transcription by directly interacting with a conserved distal regulatory element upstream of the miR-203 locus, and in doing so, orchestrated chromatin remodeling. In conclusion, our results have revealed a new regulatory mechanism that involves C/EBP&bgr;-LIP-mediated downregulation of miR-203, which plays a key role in EMT and metastasis.

Polymorphisms of decoy receptor 3 are associated with risk of esophageal squamous cell carcinoma in Chinese Han

Decoy receptor 3 (DcR3) is a soluble receptor without transmembrane and intracellular sequences in its peptide. It can bind to and inactivate the apoptosis-inducing ligand FasL, LIGHT, and TL1A. The aims of this study are to genotype the two polymorphisms in the promotor of DcR3 in esophageal squamous cell cancer patients and controls and analyze the association between individual genetic variation and susceptibility to esophageal squamous cell carcinoma (ESCC). A total of 444 Chinese ESCC patients and 468 matched cancer-free controls were evaluated for the two single nucleotide polymorphisms (SNPs) in DCR3. Polymorphisms were genotyped using the SNPShot technique. The expression of DCR3 in cancer tissues was detected by reverse transcription-polymerase chain reaction. There were significant differences in the alleles distribution of the two SNPs among ESCC cases and controls (P < 0.01). Compared with the 147TT genotype, the 147CC genotype was associated with significant elevated risk of ESCC (odds ratio, 1.89; 95% confidence interval, 1.30–2.96). The risk of 147CC genotype was more notable (odds ratio, 2.19; 95% confidence interval, 1.32–3.64) in the smokers than in the nonsmokers (odds ratio, 1.25; 95% confidence interval, 0.59–2.69). In the stratification analyses, we also found there was a strong correlation between 147 CC and the clinical TNM stage (P < 0.01). Furthermore, significant difference in DCR3 expression in ESCC tissues was found between subgroups with different 147C/T variant. Our finding suggested that DcR3 promoter polymorphism 147C/T might influence the susceptibility to ESCC in the Chinese Han population, maybe by influencing DcR3 expression.

An association study on genetic polymorphisms of Rab37 gene with the risk of esophageal squamous cell carcinoma in a Chinese Han population.

Background: Rab37 encodes a Rab GTPase which regulates the vesicular transport of exocytosis. But the different findings in two types of cancers made its roles in oncology more confused. In this study, a clinical research on genetic polymorphisms was performed to evaluate the association between Rab37 and esophageal squamous cell carcinoma (ESCC). Methods: The mRNA expression was tested by reverse transcription-polymerase chain reaction (RT-PCR) in four ESCC cell lines. A case-control study including 212 ESCC patients and 213 cancer-free controls was genotyped by PCR-restriction fragment length polymorphism. The Hardy-Weinberg equilibrium test, association analysis and haplotype analysis were performed with SPSS and SHEsis software respectively. Results: Rab37 mRNA could be specifically detected in two ESCC cell lines, EC109 and EC9706, but not in KYS150 and KYS450. The allele, genotype and haplotype frequencies of rs9904078G>A, rs2034310T>C and rs5018106T>C, located in Rab37, did not significantly differ between the patients and the controls. No association between the polymorphisms and the TNM stages of patients was found. Conclusions: Rab37 mRNA was specifically expressed in some ESCC cell lines but its genetic polymorphisms were not associated with ESCC.

Association between SNPs in Serpin gene family and risk of esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive cancers in the world. Epidemiological survey studies have verified that the development of ESCC relates to a complex interactive process between multiple genetic susceptibilities and environmental exposure. Serpins are a broadly distributed family of protease inhibitors and have been recognized as tumor suppressors in multiple cancer types. While previous studies have reported that Serpin polymorphisms are associated with tumorigenesis, the genetic and functional single nucleotide polymorphisms (SNP) in these genes appear to be complex and remain to be elucidated. In this study, a total of 500 ESCC cases and 500 matched controls in a Southwest China population were evaluated for six SNPs in the exons of three Serpin genes (SerpinB5, SerpinB2, and SerpinE1). Among the six SNPs, the C allele of rs2289519 and rs2289520 in SerpinB5 showed decreased risk of ESCC and the variants might interact with smoking status. Haplotype analysis showed that the T-G haplotype (corresponding to rs2289519-rs2289520) increased the risk of ESCC, while the C-C haplotype decreased the risk. We also found that SerpinB5 gene mRNA expression was significantly downregulated in ESCC cell lines and patient specimen while there is no change in protein structure with different haplotypes. Our results demonstrated that the expression of SerpinB5 was downregulated in ESCC, and the positive SNPs might be associated with a risk of ESCC development.

LncRNA CASC9 promotes esophageal squamous cell carcinoma metastasis through upregulating LAMC2 expression by interacting with the CREB-binding protein

Esophageal squamous cell carcinoma (ESCC) is the main subtype of esophageal cancer. Long noncoding RNAs (lncRNAs) are thought to play a critical role in cancer development. Recently, lncRNA CASC9 was shown to be dysregulated in many cancer types, but the mechanisms whereby this occurs remain largely unknown. In this study, we found that CASC9 was significantly upregulated in ESCC tissues, with further analysis revealing that elevated CASC9 expression was associated with ESCC prognosis and metastasis. Furthermore, we found that CASC9 knockdown significantly repressed ESCC migration and invasion in vitro and metastasis in nude mice in vivo. A microarray analysis and mechanical experiments indicated that CASC9 preferentially affected gene expression linked to ECM–integrin interactions, including LAMC2, an upstream inducer of the integrin pathway. We demonstrated that LAMC2 was consistently upregulated in ESCC and promoted ESCC metastasis. LAMC2 overexpression partially compromised the decrease of cell migration and invasion capacity in CASC9 knockdowns. In addition, we found that both CASC9 and LAMC2 depletion reduced the phosphorylation of FAK, PI3K, and Akt, which are downstream effectors of the integrin pathway. Moreover, the reduction in phosphorylation caused by CASC9 depletion was rescued by LAMC2 overexpression, further confirming that CASC9 exerts a pro-metastatic role through LAMC2. Mechanistically, RNA pull-down and RNA-binding protein immunoprecipitation (RIP) assay indicated that CASC9 could bind with the transcriptional coactivator CREB-binding protein (CBP) in the nucleus. Chromatin immunoprecipitation (ChIP) assay additionally illustrated that CASC9 increased the enrichment of CBP and H3K27 acetylation in the LAMC2 promoter, thereby upregulating LAMC2 expression. In conclusion, we demonstrate that CASC9 upregulates LAMC2 expression by binding with CBP and modifying histone acetylation. Our research reveals the prognostic and pro-metastatic roles for CASC9 in ESCC, suggesting that CASC9 could serve as a biomarker for prognosis and a target for metastasis treatment.

Using PCR-RFLP technology to teach single nucleotide polymorphism for undergraduates

Recent studies indicated that the aberrant gene expression of peroxiredoxin‐6 (prdx6) was found in various kinds of cancers. Because of its biochemical function and gene expression pattern in cancer cells, the association between genetic polymorphism of Prdx6 and cancer onset is interesting. In this report, we have developed and implemented a serial experiment in molecular biology laboratory course to teach single nucleotide polymorphism (SNP) to undergraduate students majoring in molecular biology or genetics. The flanking sequence of rs4382766 was located in Prdx6 gene, which contained a restriction site of SspI, and was used as a target in this lab course. The students could mimic real research by integrating different techniques, such as database retrieving, genomic DNA isolation, PCR, and restriction enzyme assay. This serial experiment of PCR‐RFLP helps students set up intact idea of molecular biology and understand the relation among individual experiments. Students were found to be more enthusiastic during the laboratory classes than those in the former curriculum.