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The present study aimed to investigate the expression of cyclin-dependent kinase 6 (CDK6) and microRNA-126-5p (miR-126-5p) in esophageal cancer tissues and cells, and their effect on esophageal cancer cell proliferation and invasion, and to explore the potential molecular mechanisms. The relative expression levels of CDK6 and miR-126-5p in esophageal cancer tissue, paracancerous tissue, and HEEC and EC109 cells were determined and compared using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). A miR-126-5p overexpression vector was constructed and a stable EC109 cell line expressing miR-126-5p was established. The EC109 cell line was transfected with a CDK6 small interfering RNA sequence. The rate of cell proliferation was determined using the WST-8 method, and cell invasion was determined using a Transwell assay. In addition, the relative expression levels of genes were determined using RT-qPCR; the relative expression levels of proteins were determined by western blot analysis; the binding sites of CDK6 and miR-126-5p were analyzed using TargetScan software; and the interaction of CDK6 and miR-126-5p was verified using dual-fluorescence reporter gene expression. Esophageal tissues and EC109 cells expressed higher levels of CDK6 but significantly lower levels of miR-126-5p compared with adjacent tissues and HEEC cells, and their correlation coefficient between esophageal tissues and matched adjacent tissues was -7.526. The overexpression of miR-126-5p and CDK6 knockdown in the EC109 cell line inhibited cell proliferation and invasion compared with the control and NC (negative control) groups. miR-126-5p overexpression reduced the relative expression level of CDK6, and CDK6 knockdown by siRNA increased the expression of miR-126-5p. miR-126-5p regulated CDK6 expression by binding to the 3'-untranslated region of its mRNA. Overexpression miR-126-5p inhibited the proliferation and migration of esophageal cancer cells by targeting CDK6 and negatively regulating its expression. These findings contribute to the understanding of the underlying molecular mechanism of esophageal cancer., (© 2020 American Association for Anatomy.)

Aim: To study the potential prognostic role of microRNA-382 (miR-382) in esophageal squamous cell carcinoma (ESCC)., Methods: Forty six patients were divided into 2 groups according to postoperative survival time: the poor outcome group (28 patients), who showed early metastasis but no recurrence, and died within 1 year after surgery, 12 patients of the group received postoperative chemotherapy treatment that was given after early metastasis happening; the good outcome group (18 patients), who had no clinical metastasis and recurrence, and survived 5 years or more after surgery, all patients did not receive any postoperative treatment. Total RNA was extracted from the patients' formalin-fixed and paraffin-embedded esophageal cancer tissues. miR-382 level was evaluated using high-throughput real-time quantitative polymerase chain reaction analysis. The correlation between miR-382 level and clinicopathologic features was analyzed through COX regression model, and Kaplan-Meier analysis was used to analyze the relationship between miR-382 level and patient survival time., Results: miR-382 was differentially expressed in the two groups. Overall the average miR-382 level in the ESCC patients with good outcome was 9.8 ± 3.8, while miR-382 level in the ESCC patients with poor outcome was 3.0 ± 0.8. The differences of miR-382 levels between two groups were significant (P < 0.05). Kaplan-Meier analysis results showed that miR-382 expression level generally had a significant reverse-correlation with ESCC patient survival time (P < 0.001), in which the patients with higher expressions of miR-382 had a longer survival time either among individuals with the same tumor stage or among the overall patients., Conclusion: miR-382 levels are reverse-correlated with ESCC poor outcomes, suggesting that miR-382 could be a potential predictive biomarker for both prognosis and treatment of ESCC.

There have been few reports evaluating the expression and function of the microRNA miR-212 in esophageal cancer. The aim of this study was to investigate the relationship between miR-212 expression and clinicopathological factors and prognoses of esophageal cancer. MicroRNA was extracted from 46 esophageal cancer patients using the Taqman MicroRNA assay. All patients were at the same tumor node metastasis stage, but with different prognoses, and had all undergone surgery. The correlation between miR-212 expression and clinicopathological features was analyzed and the significance of miR-212 as a prognostic factor as well as its relationship with survival was determined. miR-212 expression was higher in patients with poor prognoses than in those with good prognoses (P < 0.0001). Kaplan-Meier analysis results showed that the miR-212 expression level was significantly correlated with survival time (P = 0.024). Patients with higher expression of miR-212 showed longer survival times. Cox multi-factor model analysis showed that miR-212 expression was significantly correlated with survival time (P = 0.026). mir-212 is related with prognostic factors and survival time and may be a biomarker for esophageal cancer.

The aim of this study was to investigate the significance of the microRNA miR-197 expression level in relation to clinicopathological factors and prognoses of esophageal cancer (EC). MicroRNA was extracted using the Taqman(®) MicroRNA Assay from 46 EC patients at the same tumor node metastasis (TNM) stage, but with different prognoses, who underwent surgery. Paracancerous normal tissues were used as controls. The correlation between miR-197 expression and clinicopathologic features was analyzed, and the significance of miR-197 as a prognostic factor and its relationship with survival was determined. miR-197 expression was lower in patients with poor prognosis than in those with good prognosis (P < 0.05). Kaplan-Meier analysis results showed that the miR-197 expression level is significantly correlated with survival time (P = 0.030), and that patients with higher expression of miR-197 had longer survival times. Cox multi-factor model analysis showed that patient prognosis (P = 0.001), tumor length (P = 0.010) and expression (P = 0.042), and survival time were significantly correlated, with corresponding risks of 9.183, 2.318, and 1.925, respectively. This study supports a role of miR-197 as an anti-oncogene and a biomarker for EC and its relationship with other prognostic factors and survival.

Background: Genomic aberration is a common feature of human cancers and also is one of the basic mechanisms that lead to overexpression of oncogenes and underexpression of tumor suppressor genes. Our study aims to identify frequent genomic changes and candidate copy number driving genes in esophageal squamous cell carcinoma (ESCC)., Methods: We used array comparative genomic hybridization to identify recurrent genomic alterations and screened the candidate targets of selected amplification regions by quantitative and semi-quantitative RT-PCR., Results: Thirty-four gains and 16 losses occurred in more than 50 % of ESCCs. High-level amplifications at 7p11.2, 8p12, 8q24.21, 11q13.2-q13.3, 12p11.21, 12q12 and homozygous deletions at 2q22.1, 8p23.1-p21.2, 9p21.3 and 14q11.2 were also identified. 11q13.2 was a frequent amplification region, in which five genes including CHKA, GAL, KIAA1394, LRP5 and PTPRCAP were overexpressed in tumor tissues than paracancerous normal tissues. The expression of ALG3 at 3q27.1 was higher in ESCCs, especially in patients with lymph node metastasis., Conclusions: Target gene identification of amplifications or homozygous deletions will help to reveal the mechanism of tumor formation and explore new therapy method.

Purpose: Our aim was to identify frequent genomic aberrations in both esophageal squamous cell carcinoma (ESCC) and esophageal dysplasia and to discover important copy number-driving genes and microRNAs (miRNA) in ESCC., Experimental Design: We conducted array-based comparative genomic hybridization (array CGH) on 59 ESCC resection samples and 16 dysplasia biopsy samples. Expression of genes at 11q13.3 was analyzed by real-time PCR (RT-PCR) and immunohistochemistry (IHC). Integrated analysis was conducted to identify genes or miRNAs with copy number-expression correlations., Results: Array CGH identified 11 amplifications and eight homozygous deletions in ESCC. Integrated analysis of array CGH data with matched gene expression microarray data showed that 90 overexpressed genes and 24 underexpressed genes were consistent with DNA copy number changes, including 12 copy number-driving miRNAs. In esophageal dysplasia, six gains, four losses, 12 amplifications, and four homozygous deletions were detected. Amplifications of 7p11.2 and 11q13.2-11q13.3 (CCND1) and homozygous deletion at 9p21.3 (CDKN2A) were consistent genomic changes in both dysplasia and carcinoma. ANO1 at 11q13.3 was overexpressed at the mRNA and protein levels in tumors, and higher mRNA expression was correlated with the copy number increase. In particular, ANO1 expression was elevated in moderate dysplasia compared with normal esophageal epithelium. IHC revealed that ANO1 overexpression was positively correlated with lymph node metastasis and advanced clinical stage. Knockdown of ANO1 significantly inhibited the proliferation of KYSE30 and KYSE510 cells., Conclusion: Copy number aberrations in both esophageal dysplasia and ESCC may be useful as potential biomarkers for early detection. In addition, ANO1 may be a candidate target gene in esophageal tumorigenesis.

Objective: The aim of this study was to explore the expression of activin A in esophageal squamous cell carcinoma and its clinical significance., Methods: Immunohistochemical (IHC) staining was used for detecting the expression of tissue activin A in sixty-four patients with esophageal squamous cell carcinoma, and enzyme-linked immunosorbent assay (ELISA) was used for detecting the serum activin A in the patients before and after surgery. The relationship between expression of activin A in the esophageal cancer tissue with clinicopathological features and its influence on prognosis were analyzed., Results: The positive expression rate of activin A in esophageal squamous cell carcinoma was 82.8% (53/64), and that of normal esophageal epithelium was 6.7% (2/30), showing a very significant difference between them (P < 0.001). Expression of activin A was correlated with both lymph node metastasis and invasion depth of the tumor (all P < 0.05), and the expression of activin A was positively correlated with lymph node metastasis (r = 0.321, P < 0.05) and invasion depth of the tumor (r = 0.417, P < 0.05). The serum activin A of the patients before and after surgery was (911 ± 276) pg/ml and (667 ± 236) pg/ml, respectively, showing a significant difference (P = 0.005). Univariate and multivariate analyses indicated that expression of activin A and lymph node metastasis were independent influencing factors for prognosis in patients with esophageal squamous cell carcinoma (all P < 0.05)., Conclusions: Activin A may play an important role in the pathogenesis and development of esophageal squamous cell carcinoma, and it has an important reference value in the estimation of diagnosis and prognosis for esophageal squamous cell carcinoma.

Patients at the same pathological stage of esophageal cancer (EC) that received the same surgical therapy by the same surgeon may have distinct prognoses. The current study aimed to explore the possibility of differentially- expressed microRNAs (miRNAs) underlying this phenomenon. Samples were collected from EC patients at the same tumor node metastasis (TNM) stage but with different prognoses. Paracancerous normal tissues were taken as controls. The specimens were histopathologically analyzed. Differentially-expressed miRNAs were analyzed using real-time quantitative reverse transcription polymerase chain reaction. Compared with patients with poor prognosis, those with good prognosis exhibited 88 two-fold or more than two-fold increased miRNA fragments and 4 half-decreased miRNAs. The most noticeably up-regulated miRNAs included hsa-miR-31, hsa-miR- 196b, hsa-miR-652, hsa-miR-125a-5p, hsa-miR-146b, hsa-miR-200c, hsa-miR-23b, hsa-miR-29a, hsa-miR-186, hsa-miR-205, hsa-miR-376a, hsa-miR-410, hsa-miR-532-3p, and hsa-miR-598, whereas the most significantly- downregulated miRNAs were hsa-let-7e, hsa-miR-130b, and hsa-miR-103. EC patients at same TNM stage but with different prognoses show differentially-expressed miRNAs.

Objective: This study aimed to investigate whether the miR-198 expression level is related to clinicopathological factors and prognosis of esophageal cancer., Methods: MicroRNA was extracted from esophageal cancer patients who underwent surgery for assessment using the Taqman@ MicroRNA assay. The correlation between miR-198 expression and clinicopathological features was analyzed, and the significance of miR-198 as a prognostic factor and its relationship with survival was determined., Results: MicroRNA-198 (miR-198) expression was higher in patients with poor prognosis than those with good prognosis (P < 0.05). Kaplan-Meier analysis results showed that the miR-198 expression level had a significant correlation with survival time (P = 0.030) and that patients with a higher expression of miR-198 had a shorter survival time. Cox multi-factor model analysis showed that patient prognosis (P = 0.014), tumor length (P = 0.040) and expression (P = 0.012), and survival time had a significant correlation; the corresponding risks were 7.268, 1.246, and 3.524, respectively., Conclusion: miR- 198 overexpression is involved in the poor prognosis of esophageal cancer and can be used as a biomarker for selection of cases requiring especial attention.

Risk assessment of esophageal squamous cell carcinoma (ESCC) is currently based on clinicopathological parameters. To identify genomic markers that can predict overall survival in ESCC, we performed array comparative genomic hybridization (array CGH) on a screening set of 35 tumor samples from ESCC patients. Prognosis association of the genes selected on the basis of the array CGH results was further validated by real-time PCR in two independent sample sets (n = 151 and 84). Genomic analysis revealed seven high-level amplifications and two homozygous deletions. Gain of 11q13.2 and loss of 7q34 and 18q21.1-q23 were associated with poor outcome. Gain of 11q13.2 was an independent prognostic factor and was selected for further validation. In both validation sets of samples, copy number increase of CPT1A in 11q13.2 was correlated with short overall survival (P = 0.015, n = 151 and P = 0.044, n = 84). Multivariate analysis confirmed that CPT1A gain provided prognostic information in ESCC (HR, 1.643; 95% CI: 1.076-2.509; P = 0.022; HR, 2.488; 95% CI: 1.235-5.013; P = 0.011). Immunohistochemistry showed significant correlation between strong expression of CPT1A protein and poor outcome of ESCC patients (P = 0.018, n = 73). Our data suggest that gain of CPT1A may be a candidate prognostic factor., (Copyright © 2011 Wiley-Liss, Inc.)

Protein kinase Cι (PKCι) is an atypical PKC isoform and participates in multiple aspects of the transformed phenotype in human cancer cells. We previously reported that frequent amplification and overexpression of PKCι were correlated with lymph node metastasis in primary esophageal squamous cell carcinomas (ESCC). In the present study, short interfering RNA-mediated silencing of PKCι revealed that this enzyme was required for cell migration, invasion, and resistance to anoikis. In vivo experiments showed that PKCι suppression decreased tumor growth in esophageal cancer xenografts and lung metastases in nude mice. At the molecular level, knockdown of PKCι in suspended ESCC cells caused a decrease in S-phase kinase-associated protein 2 (SKP2) that had been reported to promote resistance to anoikis via the PI3K/AKT pathway. AKT phosphorylation was abolished after PKCι suppression, but AKT activation could be refreshed by PKCι upregulation, suggesting that PKCι enhanced cell resistance to anoikis via the PKCι-SKP2-PI3K/AKT pathway. Addition of the proteasome inhibitor MG132 prevented the decrease of SKP2 in PKCι silenced cells, and polyubiquitin-SKP2 was elevated after PKCι depletion, showing that PKCι might regulate the expression of SKP2 through the ubiquitin-proteasome pathway in suspended cells. Furthermore, overexpression of SKP2 in PKCι-downregulated cells restored cell resistance to anoikis. Most importantly, PKCι expression significantly correlated with SKP2 in 133 ESCC tissues (P = 0.031). Taken together, our data show that PKCι promotes tumorigenicity and metastasis of human esophageal cancer and that SKP2 is a candidate downstream effector of PKCι signaling in ESCC., (©2011 AACR.)

We have shown earlier that overexpression of Calreticulin (CRT) contributed to a poor prognosis for patients with esophageal squamous cell carcinoma (ESCC). Here, we have shown an important role of CRT in tumorigenesis through enhancing cell motility and anoikis resistance. SiRNA-mediated knockdown of CRT caused impaired cell migration, invasion and resistance to anoikis. Notably, CRT downregulation decreased the expression of Cortactin (CTTN), which has been previously reported as a candidate oncogene associated with anoikis through the PI3K-Akt pathway. In addition, Akt phosphorylation was abolished after CRT downregulation and its activation can be refreshed by CRT upregulation, suggesting that CRT-enhanced cell resistance to anoikis through the CRT-CTTN-PI3K-Akt pathway. Moreover, the CTTN mRNA level was decreased in CRT-siRNA cells, coupled with the inactivation of STAT3. Expression of both CTTN and p-STAT3 was reduced in tumor cells following incubation with the JAK-specific inhibitor, AG490. Chromatin immunoprecipitation assay showed direct binding of p-STAT3 to the conservative STAT3-binding sequences in CTTN promoter. Furthermore, overexpression of CTTN in CRT-downregulated ESCC cells restored its motility and resistance to anoikis. This study not only reveals a role of CRT in motility promotion and anoikis resistance in ESCC cells, but also identifies CRT as an upstream regulator in the CRT-STAT3-CTTN-Akt pathway.

Aim: To investigate the effect of detachment of esophageal cancer cells from extracellular matrix on the localization of death receptor 5 (DR5) and apoptosis., Methods: Anchorage-dependent EC9706 cells of esophageal squamous cell carcinoma were pretreated or not treated with brefeldin A. Detached cells were harvested by ethylenediaminetetraacetic acid digestion. Expression and localization of DR5 in these cells were determined by immunocytochemical and immunofluorescence assays, as well as flow cytometry analysis. Apoptosis of EC9706 cells was detected by flow cytometry after stained with fluorescein isothiocyanate-labeled annexin V/propidium iodide. Activation of caspase 8 was detected by Western blot analysis., Results: Immunocytochemical assay indicated that DR5 was predominantly perinuclear in adherent cells but was mainly localized in cell membrane in detached cells. In addition, immunofluorescence assay also confirmed the above-mentioned results, and further demonstrated that DR5 was present in the form of coarse granules in detached cells, but in the form of fine granules in adherent cells. Cytometry analysis revealed higher levels of DR5 expression on the surfaces of brefeldin-A-untreated cells than on the surfaces of brefeldin-A-treated cells, but brefeldin A treatment did not affect the total DR5 expression levels. Moreover, nocodazole did not influence the extracelluar DR5 expression levels in EC9706 cells. Apoptosis assay revealed that detached cells were more sensitive to DR5 antibody-induced apoptosis than adherent cells. Western blotting showed that caspase 8 was activated in temporarily detached cells 4 h earlier than in adherent cells., Conclusion: Progress from adhesion to detachment of EC9706 cells causes DR5 relocalization, and promotes cytoplasmic translocation of DR5 to cell surfaces via a Golgi-dependent pathway. Moreover, it might also result in DR5 aggregation to render apoptosis of detached cells.