[Risk factors for esophageal cancer, and possible genetic background]

Knockdown of GBAS regulates esophageal cancer cell viability and apoptosis

Esophageal cancer (EC) is the sixth leading cause of cancer‑related mortality worldwide, with the incidence gradually increasing each year. Therefore, further clarifying the mechanism underlying the development of EC may be beneficial for identifying novel biomarkers and targets for its treatment. The present study aimed to determine the functional roles of glioblastoma‑amplified sequence (GBAS), a newly identified gene that has been reported to play crucial roles in multiple types of cancer, including in the malignant behavior of EC cells, such as cell viability, colony formation, cell apoptosis and cell cycle progression. The results of the present study revealed that, in vitro, the knockdown of GBAS significantly suppressed cell viability and colony formation in TE‑1 and KYSE‑150 cell lines, using a Celigo cell count analysis and colony formation assay respectively, whereas the apoptotic rate of EC cells was significantly increased by the knockdown of GBAS using Annexin V APC staining. Furthermore, following GBAS knockdown, the cell cycle progression of TE‑1 and KYSE‑150 cells was arrested in the G1 phase using PI staining. In conclusion, the findings of the present study suggested that GBAS may serve a role in EC by regulating cell viability, apoptosis and cell cycle progression.

Prognostic significance of FAM3C in esophageal squamous cell carcinoma

Background

Family with sequence similarity 3, member C (FAM3C) has been identified as a novel regulator in epithelial-mesenchymal transition (EMT) and metastatic progression. However, the role of FAM3C in esophageal squamous cell carcinoma (ESCC) remains unexplored. The purpose of present study is to illustrate the role of FAM3C in predicting outcomes of patients with ESCC.

Methods

FAM3C expression was measured in ESCC tissues and the matched adjacent nontumorous tissues by quantitative real-time RT-PCR and Western blot analysis. The relationship between FAM3C expression and prognosis of ESCC patients was further evaluated by univariate and multivariate regression analyses. Univariate and multivariate analyses of the prognostic factors were performed using Cox proportional hazards model.

Results

The FAM3C mRNA expression was remarkably upregulated in ESCC compared with their nontumor counterparts (P < 0.001). In addition, high expression of FAM3C was significantly associated with pT stage (P = 0.014) , pN stage (P = 0.026) and TNM stage (P = 0.003). Kaplan-Meier analysis showed that the 7-year overall survival rate in the group with high expression of FAM3C was poorer than that in low expression group (32.0 versus 70.9 %; P < 0.001). Univariate and multivariate analyses demonstrated that FAM3C was an independent risk factor for overall survival. Moreover, Stratified analysis revealed that FAM3C expression could differentiate the prognosis of patients in early clinical stage (TNM stage I-II).

Conclusions

FAM3C expression was dramatically increased in ESCC and might serve as a valuable prognostic indicator for ESCC patients after surgery.

Association of genetic polymorphisms in PRKDC and XRCC4 with risk of ESCC in a high-incidence region of North China

BACKGROUND

The nonhomologous end-joining (NHEJ) pathway is the main mechanism repairing DNA double-strand breaks (DSBs) in human cells. This research was designed to study the association between selected variants in NHEJ members and esophageal squamous cell carcinoma (ESCC).

METHODS

Two single nucleotide polymorphisms (SNPs), PRKDC (rs7003908) and X-ray repair cross complementing group 4 (XRCC4; rs1805377), were genotyped in a total of 189 patients with ESCC and 189 unrelated control individuals in a high-risk area for ESCC in North China, and the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was applied.

RESULTS

A significantly different distribution was found in the frequency of PRKDC (rs7003908) genotype between the ESCC group and controls. Individuals homozygous for the C allele had a significant (3.185-fold) increased risk of ESCC. As for XRCC4 (rs1805377) polymorphism, no difference was found in distribution between the ESCC and control groups.

CONCLUSIONS

Our results suggest that variation in DNA repair genes may be associated with risk of ESCC.

Pilot genome-wide study of tandem 3' UTRs in esophageal cancer using high-throughput sequencing

Regulatory regions within the 3' untranslated region (UTR) influence polyadenylation (polyA), translation efficiency, localization and stability of mRNA. Alternative polyA (APA) has been considered to have a key role in gene regulation since 2008. Esophageal carcinoma is the eighth most common type of cancer worldwide. The association between polyA and disease highlights the requirement for comprehensive characterization of genome-wide polyA profiles. In the present study, global polyA profiles were established using the sequencing APA sites (SAPAS) method in order to elucidate the interrelation between 3' UTR length and the development of esophageal cancer. PolyA profiles were analyzed in squamous cell carcinoma, with ~903 genes identified to have shortened 3' UTRs and 917 genes identified to use distal polyA sites. The genes with shortened 3' UTRs were primarily associated with adherens junctions and the cell cycle. Four differentially expressed genes were also found, among which three genes were observed to be upregulated in cancerous tissue and involved in the positive regulation of cell motion, migration and locomotion. One gene was found to be downregulated in cancerous tissue, and associated with oxidative phosphorylation. These findings suggest that esophagitis may have a key role in the development of esophageal carcinoma. Furthermore, the genes with tandem 3' UTRs and differential expression identified in the present study may have the potential to be used as biomarkers for the diagnosis and prognosis of esophageal cancer.

Downregulation of LGI1 promotes tumor metastasis in esophageal squamous cell carcinoma

Here, we report the characterization of a candidate tumor suppressor gene leucine-rich glioma inactivated 1 (LGI1) in human esophageal squamous cell carcinoma (ESCC). Downregulation of LGI1 has been detected in approximately 50% of primary ESCCs, which was significantly associated with advanced clinical stage (P < 0.001), lymph node metastasis (P < 0.001), tumor invasion (P = 0.009) and poor disease-specific survival (P < 0.001). Functional studies found that LGI1 could inhibit cell growth, clonogenicity, cell motility and tumor formation in nude mice. Mechanistic investigations suggested that LGI1 acted through extracellular signal-regulated kinase (ERK1/2) signaling to downregulate matrix metalloproteinase (MMP)-3 expression and subsequently suppressed tumor metastasis. Taken together, our study revealed that LGI1 plays an important tumor suppressive role in the development and progression of ESCC, with possible application in clinics as a biomarker and a potential new therapeutic target.

Apurinic/apyrimidinic endonuclease-1 (APE-1) is overexpressed via the activation of NF-κB-p65 in MCP-1-positive esophageal squamous cell carcinoma tissue

Apurinic/apyrimidinic endonuclease-1 (APE-1), a key enzyme responsible for DNA base excision repair (BER), has been linked to cancer chemoradiosensitivity. The phosphorylation of p65 plays a role in the activation of this pathway. In this study, we investigated APE-1 expression and its interaction with p65 in esophageal squamous cell carcinoma (ESCC) tissue. The expression of APE-1, p65, p65 nuclear localization sequence (p65-NLS), and monocyte chemoattractant protein-1 (MCP-1) was assessed by immunohistochemical analysis in 67 human ESCC tissue samples. Real-time PCR and western blotting were also performed. p65 siRNA was evaluated to determine the role of p65 in the regulation of APE-1 expression. We found nuclear localization of APE-1 in 89.6% (60/67) of ESCC tissue samples. We also observed the colocalization of p65-NLS and APE-1 in esophageal cancer tissue. In KYSE220 cells, pretreatment of MG-132 significantly abrogated upregulation of p65 and APE-1 levels induced by MCP-1, and treatment with 10 and 20 nM p65 siRNA significantly inhibited APE-1 mRNA expression. siRNA for p65 treatment significantly increased the apoptotic index in 5-FU-treated KYSE220 cells. We conclude that APE-1 is overexpressed and mainly localized in the nuclear compartment of cancer cells, and partly regulated by p65 in the NF-κB pathway in ESCC tissue.

Cytochrome P450 2E1 RsaI/PstI polymorphism and risk of esophageal cancer: A meta-analysis of 17 case-control studies

The aim of this study was to explore the cytochrome P450 2E1 (CYP2E1) RsaI/PstI polymorphism and risk of esophageal cancer (EC) in mainland Chinese populations. A systematic search of PubMed, EMBASE, Web of Science, CBM, CNKI and VIP databases for publications on the CYP2E1 RsaI/PstI polymorphism and risk of EC was performed. and the genotype data were analyzed in a meta-analysis. Odds ratios (ORs) with relevant 95% confidence intervals (CIs) were estimated to assess the association. Sensitivity analysis, test of heterogeneity and assessment of publication bias were performed. The search yielded 17 studies including 18 trails involving 1,663 cases and 2,603 controls. The meta-analyses showed a significant association between the CYP2E1 RsaI/PstI polymorphism and risk of EC in the mainland Chinese population (c2 vs. c1: OR=0.64; 95% CI, 0.50-0.81; P<0.001; c2/c2 vs. c1/c1: OR=0.73; 95% CI, 0.57-0.93; c2/c2 vs. c1/c1+c1/c2: OR=0.76; 95% CI, 0.60-0.96; P=0.02; c1/c2 vs. c1/c1: OR=0.54; 95% CI, 0.38-0.75; P<0.001; c1/c2+c2/c2 vs. c1/c1: OR=0.48; 95% CI, 0.34-0.70; P<0.001). An increased cancer risk in all genetic models was identified following stratification by ethnicity, source of controls and tumor type. In conclusion, in all genetic models, the association between the CYP2E1 RsaI/PstI polymorphism and risk of EC in the mainland Chinese population was significant. This meta-analysis suggests that the CYP2E1 RsaI/PstI polymorphism is a risk factor for EC, and the c2 allele is a factor that lowers the possibility of EC in the mainland Chinese population and this association did not change due to ethnic differences in genetic backgrounds and the environment.