Recent Advances From Basic and Clinical Studies of Esophageal Squamous Cell Carcinoma

Gender Differences in Oesophageal Squamous Cell Carcinoma in a South African Tertiary Hospital

(1) Oesophageal squamous cell carcinoma is common in Africa and has a male preponderance. The gender-based differences in clinical presentation and risk factor exposure are poorly studied in the African context. Our aim was to compare males and females with this disease. We analyzed the differences in clinical features and risk factor exposure between males and females with oesophageal cancer. (2) Data from patients presenting to a tertiary hospital in South Africa with oesophageal squamous cell carcinoma were analyzed. Data collected included patient demographics, clinical presentation, pathology and risk factor exposure. (3) Three hundred and sixty three patients were included in the study. The male to female ratio was 1.4:1. The mean age was 66 years for females and 61 years for males (p < 0.0001). A significantly larger percentage of males were underweight compared to females (60% vs. 32%, p < 0.001). There were no differences between the genders with regards to performance status, dysphagia grade and duration and tumor length, location and degree of differentiation. There were significant differences between risk factor exposure between the two genders. Smoking and alcohol consumption was an association in more than 70% of males but in less than 10% of females There was no difference survival. (4) Female patients with oesophageal squamous cell carcinoma (OSCC) are older and have a higher body mass index (BMI) than their male counterparts. Traditionally purported risk factors of smoking and alcohol consumption are infrequent associations with OSCC in female patients and other environmental risk factors may be more relevant in this gender.

Long Non-Coding RNAs as Strategic Molecules to Augment the Radiation Therapy in Esophageal Squamous Cell Carcinoma

Intrinsic resistance to ionizing radiation is the major impediment in the treatment and clinical management of esophageal squamous cell carcinoma (ESCC), leading to tumor relapse and poor prognosis. Although several biological and molecular mechanisms are responsible for resistance to radiotherapy in ESCC, the molecule(s) involved in predicting radiotherapy response and prognosis are still lacking, thus requiring a detailed understanding. Recent studies have demonstrated an imperative correlation amongst several long non-coding RNAs and their involvement in complex cellular networks like DNA damage and repair, cell cycle, apoptosis, proliferation, and epithelial-mesenchymal transition. Additionally, accumulating evidence has suggested abnormal expression of lncRNAs in malignant tumor cells before and after radiotherapy effects in tumor cells' sensitivity. Thus, lncRNAs indeed represent unique molecules that can influence tumor cell susceptibility for various clinical interventions. On this note, herein, we have summarized the current status of lncRNAs in augmenting resistance/sensitivity in ESCC against radiotherapy. In addition, we have also discussed various strategies to increase the radiosensitivity in ESCC cells under clinical settings.

Gastrointestinal tissue-based molecular biomarkers: a practical categorisation based on the 2019 World Health Organization classification of epithelial digestive tumours

Molecular biomarkers have come to constitute one of the cornerstones of oncological pathology. The method of classification not only directly affects the manner in which patients are diagnosed and treated, but also guides the development of drugs and of artificial intelligence tools. The aim of this article is to organise and update gastrointestinal molecular biomarkers in order to produce an easy-to-use guide for routine diagnostics. For this purpose, we have extracted and reorganised the molecular information on epithelial neoplasms included in the 2019 World Health Organization classification of tumours. Digestive system tumours, 5th edn.

miR-424-5p regulates cell proliferation and migration of esophageal squamous cell carcinoma by targeting SIRT4

Objective: The present research is aimed to elucidate the expression patterns of miR-424-5p and its role in tumorigenesis and progression of esophageal squamous cell carcinoma (ESCC).

Methods: Both starBase and TCGA were utilized to assess miR-424-5p expression status in ESCC. The endogenous mRNA expression levels of miR-424-5p in ESCC and normal esophagus cell lines were detected by qRT-PCR. CCK8 and colony-forming assays were applied to determine the effects of miR-424-5p on ESCC proliferation. Transwell migration and wound healing assays were carried out to observe the changes of ESCC cell mobility after miR-424-5p mimic or inhibitor transfection. Impact of miR-424-5p on malignancy growth in vivo was further verified in a mouse xenograft model. The regulatory relationships between miR-424-5p and SIRT4 were validated by dual luciferase reporter assay, qRT-PCR and Western blot.

Results: miR-424-5p expression was found upregulated in ESCC. miR-424-5p overexpression dramatically facilitated ESCC cells proliferation and migration capacity in vitro, while downregulation of miR-424-5p displayed the opposite trend. Inhibition of xenograft tumor growth was further evidenced in vivo. Moreover, SIRT4 was confirmed to be a specific target gene of miR-424-5p in ESCC and negatively modulated by miR-424-5p. Finally, SIRT4 overexpression strongly rescued the promoting influence of miR-424-5p on the proliferative and migratory capacity of ESCC cells.

Conclusions: miR-424-5p had tumor promoting functions in proliferation and migration of ESCC by targeting SIRT4, suggesting that miR-424-5p may serve as a potential diagnostic biomarker and manipulation of miR-424-5p/SIRT4 axis could provide a novel therapeutic strategy for further ESCC treatment.

Protective effects of Alda-1, an ALDH2 activator, on alcohol-derived DNA damage in the esophagus of human ALDH2*2 (Glu504Lys) knock-in mice

Alcohol consumption is the key risk factor for the development of esophageal squamous cell carcinoma (ESCC), and acetaldehyde, a metabolite of alcohol, is an alcohol-derived major carcinogen that causes DNA damage. Aldehyde dehydrogenase2 (ALDH2) is an enzyme that detoxifies acetaldehyde, and its activity is reduced by ALDH2 gene polymorphism. Reduction in ALDH2 activity increases blood, salivary and breath acetaldehyde levels after alcohol intake, and it is deeply associated with the development of ESCC. Heavy alcohol consumption in individuals with ALDH2 gene polymorphism significantly elevates the risk of ESCC; however, effective prevention has not been established yet. In this study, we investigated the protective effects of Alda-1, a small molecule ALDH2 activator, on alcohol-mediated esophageal DNA damage. Here, we generated novel genetically engineered knock-in mice that express the human ALDH2*1 (wild-type allele) or ALDH2*2 gene (mutant allele). Those mice were crossed, and human ALDH2*1/*1, ALDH2*1/*2 and ALDH2*2/*2 knock-in mice were established. They were given 10% ethanol for 7 days in the presence or absence of Alda-1, and we measured the levels of esophageal DNA damage, represented by DNA adduct (N²-ethylidene-2′-deoxyguanosine). Alda-1 significantly increased hepatic ALDH2 activity both in human ALDH2*1/*2 and/or ALDH2*2/*2 knock-in mice and reduced esophageal DNA damage levels after alcohol drinking. Conversely, cyanamide, an ALDH2-inhibitor, significantly exacerbated esophageal DNA adduct level in C57BL/6N mice induced by alcohol drinking. These results indicate the protective effects of ALDH2 activation by Alda-1 on esophageal DNA damage levels in individuals with ALDH2 gene polymorphism, providing a new insight into acetaldehyde-mediated esophageal carcinogenesis and prevention.

Esophageal Squamous Cell Carcinoma After Radiofrequency Catheter Ablation Thermal Injury

Radiofrequency ablation is a common treatment for atrial fibrillation, and esophageal complications are exceedingly rare. This report describes the case of a patient with no other known cancer risk factors who had esophageal squamous cell carcinoma that developed at the site of esophageal thermal injury, which occurred during a radiofrequency catheter ablation procedure.

NRF2/ACSS2 axis mediates the metabolic effect of alcohol drinking on esophageal squamous cell carcinoma

Alcohol drinking is a leading risk factor for the development of esophageal squamous cell carcinoma (ESCC). However, the molecular mechanisms of alcohol-associated ESCC remain poorly understood. One of the most commonly mutated genes in ESCC is nuclear factor erythroid 2 like 2 (NFE2L2 or NRF2), which is a critical transcription factor regulating oxidative stress response and drug detoxification. When NRF2 is hyperactive in cancer cells, however, it leads to metabolic reprogramming, cell proliferation, chemoradioresistance, and poor prognosis. In this study, hyperactive NRF2 was found to up-regulate acetyl-CoA synthetase short-chain family members 2 (ACSS2), an enzyme that converts acetate to acetyl-CoA, in ESCC cells and mouse esophagus. We also showed that knockdown of NRF2 or ACSS2 led to decreased ACSS2 expression, which in turn reduced the levels of acetyl-CoA and ATP with or without ethanol exposure. In addition, ethanol exposure enhanced lipid synthesis in ESCC cells. Moreover, we observed a change in the metabolic profile of ESCC cells exposed to ethanol as a result of their NRF2 or ACSS2 status. We further showed that ACSS2 contributed to the invasive capability of NRF2high ESCC cells exposed to ethanol. In conclusion, the NRF2/ACSS2 axis mediates the metabolic effect of alcohol drinking on ESCC.

BRE Promotes Esophageal Squamous Cell Carcinoma Growth by Activating AKT Signaling

Brain and reproductive organ-expressed protein (BRE) is aberrantly expressed in multiple cancers; however, its expression pattern in human esophageal squamous cell carcinoma (ESCC) and its role in ESCC progression remain unclear. In this study, we aimed to investigate the expression pattern of BRE in human ESCC and its role in ESCC progression. BRE was overexpressed in ESCC tissues compared with that in the adjacent non-tumor tissues. Forced expression of BRE was sufficient to enhance ESCC cell growth by promoting cell cycle progression and anti-apoptosis. Silencing of BRE suppressed these malignant phenotypes of ESCC cells. Mechanistic evaluation revealed that BRE overexpression activated the phosphorylation of AKT, and inhibition of the AKT pathway by MK2206 decreased the BRE-induced cell growth and apoptotic resistance in ESCC cells, highlighting the critical role of AKT signaling in mediating the effects of BRE. Moreover, the effects of BRE on ESCC cell growth and AKT activation were verified in a xenograft model in vivo. The present results show that BRE is overexpressed in ESCC tissues and contributes to the growth of ESCC cells by activating AKT signaling both in vitro and in vivo and provide insight into the role of BRE in AKT signaling and ESCC pathogenesis.

Identification of the Prognostic Value of Immune-Related Genes in Esophageal Cancer

Esophageal cancer (EC) is a serious malignant tumor, both in terms of mortality and prognosis, and immune-related genes (IRGs) are key contributors to its development. In recent years, immunotherapy for tumors has been widely studied, but a practical prognostic model based on immune-related genes (IRGs) in EC has not been established and reported. This study aimed to develop an immunogenomic risk score for predicting survival outcomes among EC patients. In this study, we downloaded the transcriptome profiling data and matched clinical data of EC patients from The Cancer Genome Atlas (TCGA) database and found 4,094 differentially expressed genes (DEGs) between EC and normal esophageal tissue (p < 0.05 and fold change >2). Then, the intersection of DEGs and the immune genes in the “ImmPort” database resulted in 303 differentially expressed immune-related genes (DEIRGs). Next, through univariate Cox regression analysis of DEIRGs, we obtained 17 immune genes related to prognosis. We detected nine optimal survival-associated IRGs (HSPA6, CACYBP, DKK1, EGF, FGF19, GAST, OSM, ANGPTL3, NR2F2) by using Lasso regression and multivariate Cox regression analyses. Finally, we used those survival-associated IRGs to construct a risk model to predict the prognosis of EC patients. This model could accurately predict overall survival in EC and could be used as a classifier for the evaluation of low-risk and high-risk groups. In conclusion, we identified a practical and robust nine-gene prognostic model based on immune gene dataset. These genes may provide valuable biomarkers and prognostic predictors for EC patients and could be further studied to help understand the mechanism of EC occurrence and development.

LncRNA BC200 Promotes Esophageal Squamous Cell Cancer Migration and Invasion and Can Regulate ATF4 Expression

Background: The main reason for esophageal squamous cell carcinoma (ESCC) treatment failure is metastasis. Little is known about the mechanisms involved in the metastasis of ESCC, and there is a lack of effective therapeutic targets. In our previous study, we found that patients with high levels of BC200 tended to have poor prognoses.

Methods: First, we applied qRT-PCR to detect the expression level of BC200 in normal esophageal squamous epithelial cells and ESCC cells with different degrees of differentiation ability. Then, we changed BC200 expression by transfecting constructed lentiviruses that included BC200 shRNA (LV-BC200-shRNA, KD), negative control (CON053, NC), or BC200 gene (LV-BC200, BC200) to create BC200-deficient cell models in KYSE410 and KYSE70 cells and BC200 overexpression cell models in EC9706 cells and verified the transfection effect by qRT-PCR. Then, we examined cell migration by wound healing assay, invasion by Transwell assay, and proliferation by MTT assay and examined the metastasis ability in a xenograft mouse model. Gene expression profiling was performed to screen a panel of mRNAs following inhibition of BC200 expression. We then used ingenuity pathway analysis (IPA) to analyze the functions of the changed molecules and their interactions. The results from the microarray were validated by qRT-PCR and Western blotting.

Results: In this study, we found that the expression of BC200 in poorly differentiated cell lines was significantly higher than that in well-differentiated cell lines. BC200 can significantly promote the migration and invasion but not the proliferation ability of ESCC cells in vitro and BC200 shRNA can significantly suppress tumor metastasis in vivo. Our genome-wide expression profile chip showed 406 differentially expressed genes, with 91 upregulated genes and 315 downregulated genes. The upstream regulator analysis showed that ATF4 was predicted to be strongly inhibited and 21 genes were consistently inhibited by this gene. Our qRT-PCR and Western blotting data also identified the reduced expression of ATF4 and some selected downstream genes, such as SNAIL2, GADD45A, and PSAT1, as a consequence of downregulating BC200 expression in ESCC.

Conclusion: Our data showed that BC200 promoted the metastasis of ESCC cells and could regulate the expression of ATF4 and its downstream genes.

Mutational Landscape of Esophageal Squamous Cell Carcinoma in an Indian Cohort

Esophageal squamous cell carcinoma (ESCC) is the most common histological subtype of esophageal cancer in India. Cigarette smoking and chewing tobacco are known risk factors associated with ESCC. However, genomic alterations associated with ESCC in India are not well-characterized. In this study, we carried out exome sequencing to characterize the mutational landscape of ESCC tumors from subjects with a varied history of tobacco usage. Whole exome sequence analysis of ESCC from an Indian cohort revealed several genes that were mutated or had copy number changes. ESCC from tobacco chewers had a higher frequency of C:G > A:T transversions and 2-fold enrichment for mutation signature 4 compared to smokers and non-users of tobacco. Genes, such as TP53, CSMD3, SYNE1, PIK3CA, and NOTCH1 were found to be frequently mutated in Indian cohort. Mutually exclusive mutation patterns were observed in PIK3CA-NOTCH1, DNAH5-ZFHX4, MUC16-FAT1, and ZFHX4-NOTCH1 gene pairs. Recurrent amplifications were observed in 3q22-3q29, 11q13.3-q13.4, 7q22.1-q31.1, and 8q24 regions. Approximately 53% of tumors had genomic alterations in PIK3CA making this pathway a promising candidate for targeted therapy. In conclusion, we observe enrichment of mutation signature 4 in ESCC tumors from patients with a history of tobacco chewing. This is likely due to direct exposure of esophagus to tobacco carcinogens when it is chewed and swallowed. Genomic alterations were frequently observed in PIK3CA-AKT pathway members independent of the history of tobacco usage. PIK3CA pathway can be potentially targeted in ESCC which currently has no effective targeted therapeutic options.

LINC00673 Represses CDKN2C and Promotes the Proliferation of Esophageal Squamous Cell Carcinoma Cells by EZH2-Mediated H3K27 Trimethylation

Long non-coding RNAs (lncRNAs), some of the most abundant epigenetic regulators, play an important role in esophageal squamous cell carcinoma (ESCC). In the current study, the functions and mechanisms of the lncRNA LINC00673 were investigated. The expression levels of LINC00673 and its potential target genes were assessed by quantitative real-time polymerase chain reaction (qPCR) in ESCC surgical specimens and ESCC cell lines. RNA fluorescence in situ hybridization (RNA FISH) was employed to detect the subcellular location and the levels of LINC00673 in ESCC samples from patients with different survival times. LINC00673 function in ESCC carcinogenesis was also evaluated in vivo and in vitro. Cell cycle synchronization was performed using serum withdrawal; the cell cycle was monitored by fluorescence analysis and cellular DNA was detected by flow cytometry. The molecular mechanisms underlying LINC00673 were explored via Western blotting, chromatin immunoprecipitation (ChIP), and ChIP-PCR. Up-regulated LINC00673 was associated with poor prognosis in ESCC patients and promoted the proliferation of ESCC cells both in vitro and in vivo. Compared to the control group, depletion of LINC00673 in ESCC cells arrested the cell cycle, at least, at the G1/S checkpoint. Knockdown of LINC00673 significantly enhanced posttranscriptional expression of CDKN2C, and histone 3 lysine 27 trimethylation (H3K27me3) was enriched at the promoter region of CDKN2C. After inhibiting EZH2, the CDKN2C expression levels were increased. The present findings are the first to reveal that LINC00673 represses CDKN2C expression and promotes ESCC cell proliferation by elevating EZH2-mediated H3K27me3 levels. These data suggest that LINC00673 regulates the cell cycle in ESCC and that it is a promising target for clinical therapy.

Δ133p53/FLp53 Predicts Poor Clinical Outcome in Esophageal Squamous Cell Carcinoma

Background

p53 isoform Δ133p53 is directly transactivated by p53 and antagonizes p53 activities in cancer progression. However, its correlation with prognosis and cancer recurrence in esophageal squamous cell carcinoma (ESCC) is still unclear.

Patients and Methods

Expression of Δ133p53 and Δ133p53/full-length p53 (FLp53) in tissues and serums of 180 ESCC patients was evaluated using qRT-PCR. Patients were divided into high- and low-expression groups according to the cutoff value determined by X-tile 3.6.1 software. Survival analysis was performed by the Kaplan-Meier method. Univariate and multivariate Cox survival analyses were applied to assess the hazard ratios (HRs).

Results

Tissue Δ133p53 expression and Δ133p53/FLp53 ratio were significantly increased in ESCC tissue compared with adjacent normal tissue. Pre-operative Δ133p53 expression and Δ133p53/FLp53 ratio in tissue or serum samples were positively associated with TNM stage and post-operative recurrence. Kaplan-Meier curve and multivariate cox regression analyses revealed that the tissue and serum Δ133p53/FLp53 ratios (cutoff value: 2.9160) were independent prognostic factors for overall survival (OS) and progression-free survival (PFS) in ESCC patients and showed no statistical difference in receiver-operating characteristic curve (ROC) analysis, while serum Δ133p53 showed no significant prognostic value. More importantly, the serum Δ133p53/FLp53 ratio in ESCC patients was significantly decreased within 72 h post tumor resection and patients with a consistently high serum Δ133p53/FLp53 ratio (≥2.9160) had higher recurrence rates than those with consistently low ratio values. In addition, dynamic detection in each follow-up timepoint showed that serum Δ133p53/FLp53 ratios were higher than 2.9160 upon recurrence, and they even increased prior to radiologic progression.

Conclusion

The serum Δ133p53/FLp53 ratio can be a novel predictor for survival outcome and may serve as a real-time parameter for monitoring recurrence in ESCC patients after surgery.

The miR-1224-5p/TNS4/EGFR axis inhibits tumour progression in oesophageal squamous cell carcinoma

Oesophageal squamous cell carcinoma (ESCC) is a common and aggressive malignancy. Although many molecular alterations have been observed in ESCC, the mechanisms underlying the development and progression of this disease remain unclear. In the present study, miR-1224-5p was identified to be downregulated in ESCC tissues compared to normal tissues, and its low expression was correlated with shorter survival time in patients. In vitro experiments showed that miR-1224-5p inhibited the proliferation, colony formation, migration and invasion of ESCC cells. Mechanistic investigation revealed that miR-1224-5p directly targeted TNS4 and inhibited its expression, which led to the inactivation of EGFR-EFNA1/EPHA2-VEGFA (vascular endothelial growth factor A) signalling. Experiments in vivo confirmed the suppressive effect of miR-1224-5p on oesophageal cancer cells. By immunohistochemistry analysis of ESCC specimens, we found that TNS4 expression was positively correlated with that of VEGFA, and was significantly associated with lymph node metastasis and shorter survival time in patients. Together, our data suggest that miR-1224-5p downregulation is a frequent alteration in ESCC that promotes cell proliferation, migration, invasion and tumour growth by activating the EGFR-EFNA1/EPHA2-VEGFA signalling pathway via inhibition of TNS4 expression. Decreased miR-1224-5p and elevated TNS4 are unfavourable prognostic factors for ESCC patients.

AKR1C2 acts as a targetable oncogene in esophageal squamous cell carcinoma via activating PI3K/AKT signaling pathway

The aldo-keto reductases family 1 member C2 (AKR1C2) has critical roles in the tumorigenesis and progression of malignant tumours. However, it was also discovered to have ambiguous functions in multiple cancers and till present, its clinical significance and molecular mechanism in oesophageal squamous cell carcinoma (ESCC) has been unclear. The aim of this study was to explore the role of AKR1C2 in the tumorigenesis of ESCC. Here, we showed that AKR1C2 expression was found to be up-regulated in ESCC tissues and was significantly associated with pathological stage, lymph node metastasis and worse outcomes. Functional assays demonstrated that an ectopic expression of AKR1C2 in ESCC cells resulted in increased proliferation, migration and cisplatin resistance, while knockdown led to inversing effects. Bioinformation analyses and mechanistic studies demonstrated that AKR1C2 activated the PI3K/AKT signalling pathway, furthermore, the inhibitor of PI3K or the selective inhibitor of AKR1C2 enzyme activity could reverse the aggressiveness and showed synergistic antitumour effect when combined with cisplatin, both in vitro and in vivo. In conclusion, Our findings revealed that AKR1C2 could function as an oncogene by activating the PI3K/AKT pathway, as a novel prognostic biomarker and/or as a potential therapeutic target to ESCC.

Potential therapeutic effect of targeting glycogen synthase kinase 3β in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a common gastrointestinal cancer and is often refractory to current therapies. Development of efficient therapeutic strategies against ESCC presents a major challenge. Glycogen synthase kinase (GSK)3β has emerged as a multipotent therapeutic target in various diseases including cancer. Here we investigated the biology and pathological role of GSK3β in ESCC and explored the therapeutic effects of its inhibition. The expression of GSK3β and tyrosine (Y)216 phosphorylation-dependent activity was higher in human ESCC cell lines and primary tumors than untransformed esophageal squamous TYNEK-3 cells from an ESCC patient and tumor-adjacent normal esophageal mucosa. GSK3β-specific inhibitors and small interfering (si)RNA-mediated knockdown of GSK3β attenuated tumor cell survival and proliferation, while inducing apoptosis in ESCC cells and their xenograft tumors in mice. GSK3β inhibition spared TYNEK-3 cells and the vital organs of mice. The therapeutic effect of GSK3β inhibition in tumor cells was associated with G0/G1- and G2/M-phase cell cycle arrest, decreased expression of cyclin D1 and cyclin-dependent kinase (CDK)4 and increased expression of cyclin B1. These results suggest the tumor-promoting role of GSK3β is via cyclin D1/CDK4-mediated cell cycle progression. Consequently, our study provides a biological rationale for GSK3β as a potential therapeutic target in ESCC.

Significance of halofuginone in esophageal squamous carcinoma cell apoptosis through HIF-1α-FOXO3a pathway

Halofuginone (HF) from Dichroa febrifuga has shown therapeutic potential in hepatocellular, lung and colorectal cancer cell models. Evidence has also indicated that HF plays roles in caustic induced esophageal strictures and oxidative injury. However, the role of HF in esophageal squamous carcinoma (ESCC) remains unclear. In this study, we investigated HF actions and mechanisms during ESCC cell apoptosis. We observed different HF concentrations (5, 10 and 20 nM) inhibited ESCC cell survival in a time and dose-dependent manner. HF treatment markedly induced KYSE-30 and TE-1 cell apoptosis, and caspase-3 activity. Apoptosis related protein Bax expression was dramatically increased, whereas Bcl-2 levels were reduced in KYSE-30 and TE-1 cells, after HF exposure. Also, we showed that HF treatment induced DNA damage by promoting γH₂AX, pATM and pATR expression. HF treatment also reduced hypoxia-inducible factor-1α (HIF-1α) and forkhead box class O 3a (FOXO3a) expression in KYSE-30 and TE-1 cells. We also showed that HF inhibited FOXO3a expression, but this was dependent on HIF-1α inhibition. Finally, FOXO3a overexpression reversed HF induced cell survival inhibition, cell apoptosis and DNA damage. FOXO3a knockdown enhanced the effects of HF on cell survival, cell apoptosis and DNA damage. In summary, HF plays inhibitory roles in ESCC cell apoptosis, via HIF-1α-FOXO3a-dependent signaling. These data support the notion that HF could act as an effective therapeutic reagent towards ESCC.

Circular RNA LPAR3 sponges microRNA-198 to facilitate esophageal cancer migration, invasion, and metastasis

In this study, we explored expression and functions of circular RNA LPAR3 (circLPAR3) in esophageal squamous cell carcinoma (ESCC). The differential expression of circular RNAs (circRNAs) in 10 ESCC and corresponding paracarcinoma tissues was analyzed through circRNA microarray, then the candidate circRNAs were detected and verified through quantitative RT-PCR, and a novel circRNA was screened, which was circLPAR3. Circular RNA LPAR3 showed apparently high expression in ESCC tissues and cells, which was closely correlated with the clinical stage and lymph node metastasis of ESCC patients. Circular RNA LPAR3 was mainly located in the cytoplasm of ESCC cells, which was more stable than the baseline gene. Circular RNA LPAR3 upregulated MET gene expression through sponge adsorption of microRNA (miR)-198, activated the RAS/MAPK and the PI3K/Akt pathways, and promoted ESCC cell migration, invasion, and metastasis in vivo and in vitro. However, it had no effect on ESCC cell proliferation. Circular RNA LPAR3 can regulate the miR-198-MET signal axis to promote the migration, invasion, and metastasis of esophageal cancer cells, which can thereby serve as a potential diagnostic and therapeutic target of esophageal cancer.

LINC00662 promotes cell viability and metastasis in esophageal squamous cell carcinoma by sponging miR-340-5p and upregulating HOXB2

Background

Previous studies have shown that lncRNA LINC00662 plays an important role in pathogenesis of malignancies. The purpose of this study was to elucidate the regulatory mechanism of LINC00662 in esophageal squamous cell carcinoma (ESCC).

Methods

In this study, the regulatory mechanism of LINC00662 was investigated by RT‐qPCR. MTT, transwell and dual luciferase reporter assays.

Results

Upregulation of LINC00662 was found in ESCC and associated with worse clinical outcomes in ESCC patients. More importantly, knockdown of LINC00662 restrained cell proliferation, migration and invasion in ESCC. In addition, LINC00662 acts as a molecular sponge for miR‐340‐5p in ESCC, and miR‐340‐5p directly targets HOXB2. HOXB2 expression can be positively regulated by LINC00662 in ESCC. Furthermore, HOXB2 downregulation or miR‐340‐5p overexpression weakened the carcinogenesis of LINC00662 in ESCC.

Conclusions

LncRNA LINC00662 promotes the progression of ESCC by upregulating HOXB2 by sponging miR‐340‐5p.

Picropodophyllotoxin, an Epimer of Podophyllotoxin, Causes Apoptosis of Human Esophageal Squamous Cell Carcinoma Cells Through ROS-Mediated JNK/P38 MAPK Pathways

Esophageal squamous cell carcinoma (ESCC), a major histologic type of esophageal cancer, is one of the frequent causes of cancer-related death worldwide. Picropodophyllotoxin (PPT) is the main component of Podophyllum hexandrum root with antitumor activity via apoptosis-mediated mechanisms in several cancer cells. However, the underlying mechanism of the PPT effects in apoptosis induction in cancer remains ambiguous. Hence, in this study, we evaluate the anti-cancer effects of PPT in apoptotic signaling pathway-related mechanisms in ESCC cells. First, to verify the effect of PPT on ESCC cell viability, we employed an MTT assay. PPT inhibited the viability of ESCC cells in time- and dose-dependent manners. PPT induced G2/M phase cell cycle arrest and annexin V-stained cell apoptosis through the activation of the c-Jun N-terminal kinase (JNK)/p38 pathways. Furthermore, the treatment of KYSE 30 and KYSE 450 ESCC cells with PPT induced apoptosis involving the regulation of endoplasmic reticulum stress- and apoptosis-related proteins by reactive oxygen species (ROS) generation, the loss of mitochondrial membrane potential, and multi-caspase activation. In conclusion, our results indicate that the apoptotic effect of PPT on ESCC cells has the potential to become a new anti-cancer drug by increasing ROS levels and inducing the JNK/p38 signaling pathways.

HOXC10 upregulation confers resistance to chemoradiotherapy in ESCC tumor cells and predicts poor prognosis

Esophageal squamous cell carcinoma (ESCC) is a malignant disease and is a common cause of death in China. By performing an integrative study investigating public databases and clinical samples collected by our group, we found that HOXC10 (homeobox C10) is upregulated in ESCC tumor tissues compared with nontumor tissues and that the upregulation of HOXC10 is correlated with the poor prognosis of patients with ESCC. The enforced expression of HOXC10 promoted ESCC cell proliferation in vitro and in vivo. Our study revealed that HOXC10 could bind the promoter region of human Erb-b2 receptor tyrosine kinase 3 (ERBB3/HER3) and activate the PI3K/AKT pathway. In addition, by immunoprecipitation and mass spectrometry analysis, we found that HOXC10 could bind X-ray repair cross complementing 6 (Ku70) and accelerate the DNA repair mechanism via the nonhomologous end-joining (NHEJ) pathway. We further evaluated HOXC10 expression in ESCC patients receiving adjuvant radiotherapy or platinum-based chemotherapy. The results demonstrate that HOXC10 upregulation predicts the poor prognosis of ESCC patients receiving adjuvant radiotherapy or chemotherapy. Our study reveals that HOXC10 upregulation reflects the poor prognosis of ESCC patients and directs the selection of postoperative therapy regimens.

LncRNA WDFY3-AS2 suppresses proliferation and invasion in oesophageal squamous cell carcinoma by regulating miR-2355-5p/SOCS2 axis

Long non‐coding RNAs (lncRNAs) widely participate in ESCC development and progression; however, the prognostic factors and therapeutic strategies implicated in ESCC development and progression remain to be under investigation. The purpose of the current study was to explore whether WDFY3‐AS2 may be a potential prognostic factor and investigate its biological functions in ESCC. Here, WDFY3‐AS2 was frequently down‐regulated in ESCC tissues and cells, and its expression was correlated with TNM stage, lymph node metastasis and poor prognosis of ESCC patients. Moreover, WDFY3‐AS2 down‐regulation significantly promoted cell proliferation and invasion, whereas WDFY3‐AS2 up‐regulation markedly suppressed cell proliferation and invasion in ESCC EC9706 and TE1 cells, coupled with EMT phenotype alterations. WDFY3‐AS2 functioned as a competing endogenous RNA (ceRNA) for sponging miR‐2355‐5p, further resulted in the up‐regulation of its target gene SOCS2, followed by suppression of JAK2/Stat5 signalling pathway, to suppress ESCC cell proliferation and invasion in EC9706 and TE1 cells. These findings suggest that WDFY3‐AS2 may participate in ESCC development and progression, and may be a novel prognostic factor for ESCC patients, and thus targeting WDFY3‐AS2/miR‐2355‐5p/SOCS2 signalling axis may be a novel therapeutic strategy for ESCC patients.

CD36 Expression Is Associated with Cancer Aggressiveness and Energy Source in Esophageal Squamous Cell Carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is an important cause of cancer-related death worldwide. CD36, a long-chain fatty acid (FA) receptor, can initiate metastasis in human oral squamous cell carcinoma (SCC), and its expression is associated with poor prognosis in several cancers. The clinical significance of CD36 expression and its function in ESCC remain unknown.

METHODS

We examined the clinical significance of CD36 expression in 160 ESCC samples using immunohistochemical staining. Functional analysis was performed to determine the association between CD36 and ESCC characteristics (proliferative ability, invasive ability, and energy source dependency).

RESULTS

Thirty (18.8%) ESCC cases showed high CD36 expression, indicating a significant association with progression. CD36 suppression inhibited proliferation and invasiveness in ESCC cells. ESCC cells with CD36 suppression used specific essential amino acids (EAAs) as energy sources. Cell viability depended on FAs under CD36 expression. The viability of ESCC cells with CD36 suppression depended on EAAs but not FAs.

CONCLUSIONS

CD36 may be a good biomarker and therapeutic target in ESCC. Our data provide new insights into the basic mechanism of CD36-dependent energy utilization for ESCC survival. CD36 might be a key regulator of the dependency of FAs as energy source in ESCC cells.

Glycogen Synthase Kinase 3β in Cancer Biology and Treatment

Glycogen synthase kinase (GSK)3β is a multifunctional serine/threonine protein kinase with more than 100 substrates and interacting molecules. GSK3β is normally active in cells and negative regulation of GSK3β activity via phosphorylation of its serine 9 residue is required for most normal cells to maintain homeostasis. Aberrant expression and activity of GSK3β contributes to the pathogenesis and progression of common recalcitrant diseases such as glucose intolerance, neurodegenerative disorders and cancer. Despite recognized roles against several proto-oncoproteins and mediators of the epithelial–mesenchymal transition, deregulated GSK3β also participates in tumor cell survival, evasion of apoptosis, proliferation and invasion, as well as sustaining cancer stemness and inducing therapy resistance. A therapeutic effect from GSK3β inhibition has been demonstrated in 25 different cancer types. Moreover, there is increasing evidence that GSK3β inhibition protects normal cells and tissues from the harmful effects associated with conventional cancer therapies. Here, we review the evidence supporting aberrant GSK3β as a hallmark property of cancer and highlight the beneficial effects of GSK3β inhibition on normal cells and tissues during cancer therapy. The biological rationale for targeting GSK3β in the treatment of cancer is also discussed at length.

Synthetic Lethality with Trifluridine/Tipiracil and Checkpoint Kinase 1 Inhibitor for Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is a disease characterized by a high mutation rate of the TP53 gene, which plays pivotal roles in the DNA damage response (DDR) and is regulated by checkpoint kinase (CHK) 2. CHK1 is another key DDR-related protein, and its selective inhibition is suggested to be particularly sensitive to TP53-mutated cancers, because a loss of both pathways (CHK1 and/or CHK2-p53) is lethal due to the serious impairment of DDR. Such a therapeutic strategy is termed synthetic lethality. Here, we propose a novel therapeutic strategy based on synthetic lethality combining trifluridine/tipiracil and prexasertib (CHK1 inhibitor) as a treatment for ESCC. Trifluridine is a key component of the antitumor drug combination with trifluridine/tipiracil (an inhibitor of trifluridine degradation), also known as TAS-102. In this study, we demonstrate that trifluridine increases CHK1 phosphorylation in ESCC cells combined with a reduction of the S-phase ratio as well as the induction of ssDNA damage. Because CHK1 phosphorylation is considered to be induced as DDR for trifluridine-mediated DNA damage, we examined the effects of CHK1 inhibition on trifluridine treatment. Consequently, CHK1 inhibition by short hairpin RNA or treatment with the CHK1 inhibitor, prexasertib, markedly enhanced trifluridine-mediated DNA damage, represented by an increase of γH2AX expression. Moreover, the combination of trifluridine/tipiracil and CHK1 inhibition significantly suppressed tumor growth of ESCC-derived xenograft tumors. Furthermore, the combination of trifluridine and prexasertib enhanced radiosensitivity both in vitro and in vivo Thus, the combination of trifluridine/tipiracil and a CHK1 inhibitor exhibits effective antitumor effects, suggesting a novel therapeutic strategy for ESCC.

XPD inhibits cell growth and invasion and enhances chemosensitivity in esophageal squamous cell carcinoma by regulating the PI3K/AKT signaling pathway

Esophageal squamous cell carcinoma (ESCC) is a lethal disease due to its high aggressiveness. The aim of the present study was to investigate the role of xeroderma pigmentosum complementation group D (XPD) in the growth and invasion of ESCC and to elucidate the potential underlying molecular mechanisms. Western blot analysis and RT-qPCR were used to detect the expression level of XPD in ESCC tissue samples and adjacent normal esophageal tissue samples. The pEGFP-N2/XPD plasmid was transfected into human ESCC cell lines (EC9706 and EC109). The proliferation, apoptosis, migration and invasion of EC9706 or EC109 cells were assessed following transfection with the XPD overexpression plasmid. The chemosensitivity of EC9706 or EC109 cells to cisplatin or fluorouracil was evaluated by CCK-8 assay. The expression levels of phosphoinositide 3-kinase (PI3K)/AKT, nuclear factor (NF)-κB, Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) and mitogen-activated protein kinase (MAPK) signaling pathway-related genes were detected by RT-qPCR and western blot analysis. The results demonstrated that the expression level of XPD was markedly lower in ESCC tissue samples than in adjacent normal esophageal tissue samples. The pEGFP-N2/XPD plasmid was successfully transfected into EC9706 or EC109 cells, inducing XPD overexpression. A High XPD expression markedly suppressed cell proliferation, migration and invasion, and increased the apoptotic rate of EC9706 and EC109 cells. Furthermore, the overexpression of XPD significantly increased the chemosensitivity of EC9706 and EC109 cells to cisplatin or fluorouracil. Following XPD overexpression, the expression levels of PI3K, p-AKT, c-Myc, Cyclin D1, Bcl-2, vascular endothelial growth factor (VEGF) and matrix metalloproteinase (MMP)-9 were markedly downregulated, while the expression level of p21 was markedly upregulated. On the whole, the findings of the present study demonstrate that XPD inhibits the growth and invasion of EC9706 and EC109 cells, whilst also enhancing the chemosensitivity of EC9706 and EC109 cells to cisplatin or fluorouracil by regulating the PI3K/AKT signaling pathway. XPD may thus be an underlying target for ESCC treatment and drug resistance.

β-elemene suppresses the malignant behavior of esophageal cancer cells by regulating the phosphorylation of AKT

BACKGROUND

Esophageal cancer is a digestive tract malignancy, ranking sixth among the world's deadliest tumor incidence. However, the pathogenesis of esophageal cancer is complex and the prognosis remains poor. Therefore, in-depth study of the pathogenesis and developing effective treatments are of great value for esophageal cancer. β-elemene is a natural monomeric compound derived from the Chinese herbal Curcuma wenyujin. β-elemene has been reported to have anti-tumor effects and used as an adjunct to clinical therapy for multiple cancers. This study aims to explore the effects of β-elemene on esophageal cancer and its related molecular mechanisms.

METHODS

TE-1 and KYSE-150 cells were used to evaluate the activity of β-elemene on esophageal cancerin vitro and in vivo. Western blot was performed for protein expression assessment. CCK8 assay and cell cycle analysis were used for proliferation testing. Flow cytometry was performed for apoptosis detection. Wound healing assay was subjected to assess the migration ability. Transwell chamber assay was applied to assess the invasion ability. HE staining, TUNEL staining and immunohistochemical staining were used to evaluate the changes in tumor tissues.

RESULTS

We found that β-elemene treatment suppressed proliferation, as well as induced apoptosis of esophageal cancer cells. In addition, β-elemene inhibited the migration and invasion ability of esophageal cancer cells. Furthermore, β-elemene exerted its effects against esophageal cancer by specifically regulating AKT signaling, thereby controlling the expression of PD-L1.

CONCLUSION

β-elemene inhibits proliferation and metastasis of esophageal cancer cells by regulating the phosphorylation of AKT.

Prdx1 promotes the loss of primary cilia in esophageal squamous cell carcinoma

Background

Loss of primary cilia is frequently observed in tumor cells, suggesting that the absence of this organelle may promote tumorigenesis through aberrant signal transduction, the inability to exit the cell cycle, and promotion of tumor cell invasion. Primary cilia loss also occurs in esophageal squamous cell carcinoma (ESCC) cells, but the molecular mechanisms that explain how ESCC cells lose primary cilia remain poorly understood.

Methods

Inhibiting the expression of Prdx1 in the ESCC cells to detect the up-regulated genes related to cilium regeneration and down-regulated genes related to cilium disassembly by Gene chip. And, mice and cell experiments were carried to confirm the role of the HEF1-Aurora A-HDAC6 signaling axis in ESCC.

Results

In this study, we found that silencing Peroxiredoxin 1 (Prdx1) restores primary cilia formation, and over-expressing Prdx1 induces primary cilia loss in ESCC cells. We also showed that the expression of Prdx1 regulates the action of the HEF1-Aurora A-HDAC6 signaling axis to promote the disassembly of primary cilia, and suppression of Prdx1 results in decreased tumor formation and tumor mass volume in vivo.

Conclusions

These results suggest that Prdx1 is a novel regulator of primary cilia formation in ESCC cells.

Decreased ZNF750 promotes angiogenesis in a paracrine manner via activating DANCR/miR-4707-3p/FOXC2 axis in esophageal squamous cell carcinoma

ZNF750 is one novel significantly mutated gene identified in esophageal squamous cell carcinoma (ESCC) using next-generation sequencing. However, its clinically relevant and potential mechanisms have remained elusive. Using genomic sequencing of 612 ESCC patients, we analyzed the associations of ZNF750 mutations with clinicopathologic features and its prognostic value. We further investigated the function and underlying mechanism of ZNF750 in angiogenesis. The results showed ZNF750 mutations/deletions are significantly associated with malignant progression and poor prognosis of ESCC patients. Decreased ZNF750 in ESCC cells induces enhanced angiogenesis of human umbilical vein endothelial cells (HUVECs) and human arterial endothelial cells (HAECs), and the effect may be indirectly mediated by FOXC2. RNA-seq and ChIP shows lncRNA DANCR is a direct downstream target of ZNF750. Furtherly, knockdown ZNF750 evokes DANCR expression, which prevents miR-4707-3p to interact with FOXC2 as a microRNA sponge in a ceRNA manner, leading to enhanced FOXC2 signaling and angiogenesis. In contrast, ZNF750 expression reverses the effect. Our study reveals a novel mechanism of ZNF750, highlights a significance of ZNF750 as a metastatic and prognostic biomarker, and offers potential therapeutic targets for ESCC patients harboring ZNF750 mutations.

Diagnostic model of combined ceRNA and DNA methylation related genes in esophageal carcinoma

Esophageal cancer is a common malignant tumor in the world, and the aim of this study was to screen key genes related to the development of esophageal cancer using a variety of bioinformatics analysis tools and analyze their biological functions. The data of esophageal squamous cell carcinoma from the Gene Expression Omnibus (GEO) were selected as the research object, processed and analyzed to screen differentially expressed microRNAs (miRNAs) and differential methylation genes. The competing endogenous RNAs (ceRNAs) interaction network of differentially expressed genes was constructed by bioinformatics tools DAVID, String, and Cytoscape. Biofunctional enrichment analysis was performed using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG). The expression of the screened genes and the survival of the patients were verified. By analyzing GSE59973 and GSE114110, we found three down-regulated and nine up-regulated miRNAs. The gene expression matrix of GSE120356 was calculated by Pearson correlation coefficient, and the 11696 pairs of ceRNA relation were determined. In the ceRNA network, 643 lncRNAs and 147 mRNAs showed methylation difference. Functional enrichment analysis showed that these differentially expressed genes were mainly concentrated in the FoxO signaling pathway and were involved in the corresponding cascade of calcineurin. By analyzing the clinical data in The Cancer Genome Atlas (TCGA) database, it was found that four lncRNAs had an important impact on the survival and prognosis of esophageal carcinoma patients. QRT-PCR was also conducted to identify the expression of the key lncRNAs (RNF217-AS1, HCP5, ZFPM2-AS1 and HCG22) in ESCC samples. The selected key genes can provide theoretical guidance for further research on the molecular mechanism of esophageal carcinoma and the screening of molecular markers.

Refractory solitary cervical lymph node metastasis after esophageal squamous cell carcinoma surgery and its successful treatment with immune checkpoint inhibitor: A case report and literature review

RATIONALE

Although the early detection and treatment of non-metastatic esophageal cancer has improved, these patients' prognoses are still poor. Most patients with radical treatment for esophageal cancer will relapse in 3 years, and the best treatment strategy after recurrence has not been uniformly accepted. Multiform treatments may be beneficial to recurrent patients.

PATIENT CONCERNS

A 60-year-old male patient, due to routinely health examination, ulcerated lesions 30 cm away from the incisors were found by gastroscopy, pathology showed esophageal squamous cell carcinoma (ESCC).

DIAGNOSIS

Due to the patient's pathology, he was diagnosed with ESCC.

INTERVENTIONS

The patient underwent radical surgery for ESCC on June 28, 2015. The left cervical lymph node metastasis occurred after 20 months, and lymph node metastasis carcinoma resection was performed. After that, concurrent chemoradiotherapy was implemented, 40 days after the end of the 4 courses of chemotherapy, the left cervical metastatic lymph nodes relapsed, radioactive particle implantation was carried out, and progressed again after 1 month. The patient took apatinib for 1 week but could not tolerate due to hand-foot syndrome. Immune checkpoint inhibitor (ICI) was administered since October 27, 2017.

OUTCOMES

The therapeutic effect of immune checkpoint inhibitor was evaluated as partial response (PR) after 6 courses of treatment and complete response (CR) after 15 courses of treatment. To our knowledge, this is the first case report of successful immunotherapy for refractory esophageal squamous cell carcinoma.

LESSONS

The emergence of ICIs promotes the treatment of esophageal cancer to a new era. Our observations suggest that patients for whom schedule to receive anti-programmed cell death protein-1 (anti-PD-1)/programmed cell death-ligand 1 (PD-L1) immunotherapy may require genomic testing to predict whether tumors respond to ICIs. In this case, we also present the predictors for the efficacy of targeted immunotherapy. At present, no matter which predictor of PD-L1 expression, tumor mutational burden (TMB), microsatellite instability (MSI), and tumor-infiltrating lymphocyte (TIL), a single predictor may be unconvincing and cannot accurately estimate the efficacy of immunotherapy. Multiplex detecting methods and combined biomarkers may provide new strategies. Consensus need to be reached in order to be widely applied in future studies.

Long noncoding RNA SNHG12 suppresses esophageal squamous cell carcinoma progression through competing endogenous RNA networks

PURPOSE

Esophageal squamous cell cancer (ESCC) has high rates of recurrence and mortality. Small nucleolar RNA host gene 12 (SNHG12) is known to promote the progression of several cancers. Therefore, we aimed to investigate the expression and role of SNHG12 in ESCC.

METHODS

The expression and clinical value of SNHG12 in esophageal cancer were explored using data from The Cancer Genome Atlas (TCGA) and the online server GEPIA. Real-time quantitative polymerase chain reaction (qRT-PCR) was used to verify the expression levels of SNHG12 in ESCC tissues and cell lines. Furthermore, loss-of-function assays were performed to examine the effect of SNHG12 on ESCC cells in vitro and in vivo. The potential competing endogenous RNA networks of SNHG12 in ESCC were explored.

RESULTS

SNHG12 was downregulated in human ESCA tissues compared to control tissues. The expression of SNHG12 was strongly associated with T stage, N stage, and TNM stage. Low SNHG12 expression in esophageal tumor tissues was significantly correlated with poor prognosis. Furthermore, knockdown of SNHG12 not only promoted proliferation, colony formation, migration, and invasion and inhibited apoptosis in ESCC cells in vitro, but also increased tumor growth in vivo. Additionally, this proves that the SNHG12/miRNA-195-5p/BCL9 network might be involved in ESCC.

CONCLUSION

This is the first study to reveal that SNHG12 is downregulated in ESCC tissues and could be used as a prognostic tool. SNHG12 suppressed tumor progression in ESCC cells, serving as a potential biomarker. The SNHG12/miRNA-195-5p/BCL9 network is proposed to be the mechanism leading to ESCC progression.

Cellular Dissociation Grading Based on the Parameters Tumor Budding and Cell Nest Size in Pretherapeutic Biopsy Specimens Allows for Prognostic Patient Stratification in Esophageal Squamous Cell Carcinoma Independent From Clinical Staging

Initial treatment planning in esophageal squamous cell carcinoma mainly relies on clinical staging. Recently, a highly prognostic grading system based on the cellular dissociation parameters Tumor Budding and Cell Nest Size has been proposed for resected esophageal squamous cell carcinoma. To probe for the transferability and relevance of this established novel grading system in the pretreatment setting, we evaluated Tumor Budding/Cell Nest Size in pretherapeutic biopsies of either primarily resected (cohort 1, n=80) or neoadjuvantly treated (cohort 2, n=75) esophageal squamous cell carcinoma. Grading data were correlated with clinicopathologic and survival parameters. High Tumor Budding Activity and small Cell Nest Size in pretherapeutic biopsies were strongly associated with shortened overall survival, disease-free survival, and disease-specific survival in both cohorts. A modified histopathologic grading system incorporating both factors termed "Cellular Dissociation Grade" showed excellent prognostic demarcation between well (G1), moderately (G2), and poorly differentiated (G3) carcinomas in both scenarios (overall survival: cohort 1: P<0.001; cohort 2: P=0.009) and was predictive for a high pathologic tumor stage and the presence of nodal metastases in primarily resected patients. Multivariate analyses revealed the Cellular Dissociation Grade to be a predictor of poor outcome in the pretherapeutic setting independent of clinical stage (overall survival, disease-free survival, and disease-specific survival: P<0.001). Hazard ratio for disease-free survival was 3.19 for G2 and 5.66 for G3 carcinomas compared with G1 neoplasms. Our data not only prove the transferability of histopathologic grading based on Tumor Budding/Cell Nest Size to biopsy specimens in esophageal squamous cell carcinoma, but also demonstrate that the Cellular Dissociation Grade is a strong outcome predictor in this entity even in the pretreatment scenario. Therefore, we believe that this novel type of grading has the ability to serve as a powerful histology-based pretherapeutic biomarker, that might supplement clinical staging for choosing the most suitable therapy decision.

DNA Adducts as Biomarkers To Predict, Prevent, and Diagnose Disease-Application of Analytical Chemistry to Clinical Investigations

Characterization of the chemistry, structure, formation, and metabolism of DNA adducts has been one of the most significant contributions to the field of chemical toxicology. This work provides the foundation to develop analytical methods to measure DNA adducts, define their relationship to disease, and establish clinical tests. Monitoring exposure to environmental and endogenous toxicants can predict, diagnose, and track disease as well as guide therapeutic treatment. DNA adducts are one of the most promising biomarkers of toxicant exposure owing to their stability, appearance in numerous biological matrices, and characteristic analytical properties. In addition, DNA adducts can induce mutations to drive disease onset and progression and can serve as surrogate markers of chemical exposure. In this perspective, we highlight significant advances made within the past decade regarding DNA adduct quantitation using mass spectrometry. We hope to expose a broader audience to this field and encourage analytical chemistry laboratories to explore how specific adducts may be related to various pathologies. One of the limiting factors in developing clinical tests to measure DNA adducts is cohort size; ideally, the cohort would allow for model development and then testing of the model to the remaining cohort. The goals of this perspective article are to (1) provide a summary of analyte levels measured using state-of-the-art analytical methods, (2) foster collaboration, and (3) highlight areas in need of further investigation.

Development and validation of a radiomics signature on differentially expressed features of 18F-FDG PET to predict treatment response of concurrent chemoradiotherapy in thoracic esophagus squamous cell carcinoma

BACKGROUND AND PURPOSE

To investigate potential image markers for early prediction of treatment response on thoracic esophagus squamous cell carcinoma (ESCC) treated with concurrent chemoradiotherapy (CCRT).

MATERIALS AND METHODS

159 thoracic ESCC patients enrolled from two institutions were divided into training and validation sets. A total of 944 radiomics features were extracted from pretreatment ¹⁸F-FDG PET images. We first performed the inter-observer reproducibility test in 10 pairs of patients (responders vs. nonresponders), and the limma package was used to identify differentially expressed features (DEFs). Then the least absolute shrinkage and selection operator (LASSO) logistic regression model with 10-fold cross-validation was used to construct a treatment response related radiomics signature. Finally, the performance was assessed in both sets with receiver operating characteristic (ROC) curves and Kaplan-Meier analysis.

RESULTS

After the inter-observer test, 691 features were considered reproducible and been retained (ICC > 0.9). 61 DEFs were selected from limma and entered into the LASSO logistic regression model. The radiomics signature was significantly associated with treatment response in the training (p < 0.001) and validation set (p = 0.026), which achieved area under curve (AUC) values of 0.844 and 0.835, respectively. Delong test results of two ROCs showed no significant difference (p = 0.918). The cut-off value of the radiomics signature could successfully divide patients into high-risk and low-risk groups in both sets.

CONCLUSION

This study indicated that the proposed radiomics signature could be a useful image marker to predict the therapeutic response of thoracic ESCC patients treated with CCRT.

Metabolic remodeling by TIGAR overexpression is a therapeutic target in esophageal squamous-cell carcinoma

Rationale: Whole-genome sequencing has identified many amplified genes in esophageal squamous-cell carcinoma (ESCC). This study investigated the role and clinical relevance of these genes in ESCC.

Methods: We collected ESCC and non-tumor esophageal tissues from 225 individuals who underwent surgery. Clinical data were collected and survival time was measured from the date of diagnosis to the date of last follow-up or death. Patient survival was compared with immunohistochemical staining score using Kaplan-Meier methods and hazard ratios were calculated by Cox models. Cells with gene overexpression and knockout were analyzed in proliferation, migration and invasion assays. Cells were also analyzed for levels of intracellular lactate, NADPH, ATP and mRNA and protein expression patterns. Protein levels in cell line and tissue samples were measured by immunoblotting or immunohistochemistry. ESCC cell were grown as xenograft tumors in nude mice. Primary ESCC in genetically engineered mice and patient-derived xenograft mouse models were established for test of therapeutic effects.

Results: We show that TP53-induced glycolysis and apoptosis regulator (TIGAR) is a major player in ESCC progression and chemoresistance. TIGAR reprograms glucose metabolism from glycolysis to the glutamine pathway through AMP-activated kinase, and its overexpression is correlated with poor disease outcomes. Tigar knockout mice have reduced ESCC tumor burden and growth rates. Treatment of TIGAR-overexpressing ESCC cell xenografts and patient-derived tumor xenografts in mice with combination of glutaminase inhibitor and chemotherapeutic agents achieves significant more efficacy than chemotherapy alone.

Conclusion: These findings shed light on an important role of TIGAR in ESCC and might provide evidence for targeted treatment of TIGAR-overexpressing ESCC.

MiR-450a-5p inhibits autophagy and enhances radiosensitivity by targeting dual-specificity phosphatase 10 in esophageal squamous cell carcinoma

Radioresistance reduces the success of therapy for patients with ESCC. Enhancing our understanding of the cardinal principles of radioresistance may improve the response of patients to irradiation. MicroRNAs perform a key role in posttranscriptional regulation, which is linked with the response of tumors to irradiation. Here, we successfully constructed a radioresistant cell line model, ECA109R, from parental esophageal cancer cell line ECA109. We used RNA-Seq analysis and qRT-PCR to compare the miRNA expression profiles of the ECA109 and ECA109R cell lines. The results revealed that miR-450a-5p was downregulated in the radioresistant cells. Functional analysis indicated that miR-450a-5p increases cellular radiosensitivity and suppresses autophagy in ESCC cells. We utilized a luciferase reporter assay to identify the target gene, DUSP10, as an indispensable regulator of the p38 and SAPK/JNK signaling pathways. Upregulation or downregulation of DUSP10 expression could reverse the effects of miR-450a-5p overexpression or inhibition. Tumor xenograft experiments verified that miR-450a-5p overexpression could increase sensitivity to radiation therapy in vivo. In general, our findings indicate that miR-450a-5p is a latent radiosensitizer and may represent a potential novel therapeutic target for radioresistance in ESCC.

The prognostic value of a seven-lncRNA signature in patients with esophageal squamous cell carcinoma: a lncRNA expression analysis

Background

Long non-coding RNAs (lncRNAs) have been reported to be prognostic biomarkers in many types of cancer. We aimed to identify a lncRNA signature that can predict the prognosis in patients with esophageal squamous cell carcinoma (ESCC).

Methods

Using a custom microarray, we retrospectively analyzed lncRNA expression profiles in 141 samples of ESCC and 81 paired non-cancer specimens from Sun Yat-Sen University Cancer Center (Guangzhou, China), which were used as a training cohort to identify a signature associated with clinical outcomes. Then we conducted quantitative RT-PCR in another 103 samples of ESCC from the same cancer center as an independent cohort to verify the signature.

Results

Microarray analysis showed that there were 338 lncRNAs significantly differentially expressed between ESCC and non-cancer esophagus tissues in the training cohort. From these differentially expressed lncRNAs, we found 16 lncRNAs associated with overall survival (OS) of ESCC patients using Cox regression analysis. Then a 7-lncRNA signature for predicting survival was identified from the 16 lncRNAs, which classified ESCC patients into high-risk and low-risk groups. Patients with high-risk have shorter OS (HR: 3.555, 95% CI 2.195–5.757, p < 0.001) and disease-free survival (DFS) (HR: 2.537, 95% CI 1.646–3.909, p < 0.001) when compared with patients with low-risk in the training cohort. In the independent cohort, the 7 lncRNAs were detected by qRT-PCR and used to compute risk score for the patients. The result indicates that patients with high risk also have significantly worse OS (HR = 2.662, 95% CI 1.588–4.464, p < 0.001) and DFS (HR 2.389, 95% CI 1.447–3.946, p < 0.001). The univariate and multivariate Cox regression analyses indicate that the signature is an independent factor for predicting survival of patients with ESCC. Combination of the signature and TNM staging was more powerful in predicting OS than TNM staging alone in both the training (AUC: 0.772 vs 0.681, p = 0.002) and independent cohorts (AUC: 0.772 vs 0.660, p = 0.003).

Conclusions

The 7-lncRNA signature is a potential prognostic biomarker in patients with ESCC and may help in treatment decision when combined with the TNM staging system.

Cinobufagin Promotes Cell Cycle Arrest and Apoptosis to Block Human Esophageal Squamous Cell Carcinoma Cells Growth via the p73 Signalling Pathway

Cinobufagin isolated from traditional Chinese herbs has antitumour, anaesthetic, analgesic and anti-inflammatory effects. Recently, the antitumour activity of cinobufagin has attracted increasing attention from researchers. However, the anticancer activity of this drug on esophageal cancer cells and the precise mechanism are unclear. In this study, we determined the inhibitory effect of cinobufagin on the growth of three esophageal squamous cell carcinoma cell lines and explored its underlying mechanism. EC-109, Kyse-150, and Kyse-520 cells were treated with different concentrations of cinobufagin. The results of the Cell Counting Kit-8 (CCK-8) and clone formation assays showed that cinobufagin significantly reduced cell proliferation in a dose- and time-dependent manner. Also, flow cytometry and Hoechst 33342 staining indicated that the inhibition of growth induced by cinobufagin was mediated by G2/M cell cycle arrest and apoptosis. In addition, the expression of proteins related to cell cycle arrest and apoptosis was assessed by real-time quantitative (q)RT-PCR and Western blot. The results showed that cinobufagin caused G2/M arrest via upregulation of p21 and Wee1 and downregulation of cyclin B1 and Cdc2 at the mRNA and protein levels and induced apoptosis via upregulation of cleaved caspase-3, Puma and Noxa expression and an increased Bax/Bcl-2 ratio. Other data further showed that cinobufagin increased p73 expression and decreased Mdm2 expression, whereas p53 expression was not significantly changed. Taken together, these results suggest that growth inhibition of cinobufagin in esophageal cancer cells might act through the p73 pathway and its downstream molecules.

LncRNA SNHG1 Regulates the Progression of Esophageal Squamous Cell Cancer by the miR-204/HOXC8 Axis

Objective

Long noncoding RNA small nucleolar RNA host gene 1 (SNHG1) has been reported to be aberrantly expressed and plays an important role in human cancers, including esophageal squamous cell cancer. However, the regulatory mechanism underlying SNHG1 in the progression of esophageal squamous cell cancer is poorly defined.

Materials and Methods

Fifty-three esophageal squamous cell cancer patients were recruited and overall survival was analyzed. EC9706 and KYSE150 cells were cultured for study in vitro. The expression levels of SNHG1, microRNA (miR)-204 and homeobox c8 (HOXC8) were detected by quantitative real-time polymerase chain reaction and Western blot. Cell cycle distribution, apoptosis, migration and invasion were determined by flow cytometry and transwell assays, respectively. The target interaction among SNHG1, miR-204 and HOXC8 was validated by luciferase reporter assay and RNA immunoprecipitation. Xenograft model was established to investigate the role of SNHG1 in vivo.

Results

High expression of SNHG1 was exhibited in esophageal squamous cell cancer and indicated poor outcomes of patients. SNHG1 silence led to cell cycle arrest at G0-G1 phase, inhibition of migration and invasion and increase of apoptosis. miR-204 was validated to sponge by SNHG1 and target HOXC8 in esophageal squamous cell cancer cells. miR-204 knockdown or HOXC8 restoration reversed the inhibitive role of SNHG1 silence in the progression of esophageal squamous cell cancer cells. Furthermore, inhibiting SNHG1 decreased xenograft tumor growth by regulating miR-204 and HOXC8.

Conclusion

SNHG1 knockdown suppresses migration and invasion but induces apoptosis of esophageal squamous cell cancer cells by increasing miR-204 and decreasing HOXC8.

Identification of key genes and pathways associated with esophageal squamous cell carcinoma development based on weighted gene correlation network analysis

Background: As one of the most aggressive malignancies, esophageal squamous cell carcinoma(ESCC) remains one of the leading causes of cancer related death worldwide. The majority of ESCCs are diagnosed at advanced stages with poor five-year survival rate, making it urgent to identify specific genes and pathways associated with its initiation and prognosis.

Materials and Methods: The differentially expressed genes in TCGA were analysed to construct a co-expression network by WGCNA. Gene ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways analysis were performed for the selected genes. Module-clinical trait relationships were analyzed to explore the genes and pathways that associated with clinicopathological parameters of ESCC. Log-rank tests and COX regression were used to identify the prognosis-related genes.

Results: The brown module containing 716 genes which most significantly contributed to ESCC. GO analysis suggested enrichment of adaptive immune response, cyclin-dependent protein serine, regeneration and mRNA metabolic process. KEGG analysis indicated pathways including Cellular senescence, Ribosome biogenesis, Proteasome, Base excision repair and p53 signaling pathway. Clinical stage was associated with cyan module; clinical M was associated with grey60 module; clinical T was associated with darkturquoise module; while clinical N, histological type and cancer location were associated with turquoise module. Key genes of TCP1, COQ3, PTMA and MAPRE1 might be potential prognostic markers for ESCC.

Discussion: Differentially expressed genes and key modules contributing to initiation and progression in ESCC were identified by WGCNA. These findings provide novel insights into the mechanisms underlying the initiation, prognosis and treatment of ESCC.

Genome-wide Discovery of a Novel Gene-expression Signature for the Identification of Lymph Node Metastasis in Esophageal Squamous Cell Carcinoma

OBJECTIVE

This study aimed to develop a gene-expression signature for identification of lymph node (LN) metastasis in esophageal squamous cell carcinoma (ESCC) patients.

SUMMARY OF BACKGROUND DATA

LN metastasis is recognized as the most important independent risk factor for therapeutic decision-making of ESCC patients.

METHODS

A bioinformatic approach was used to analyze RNA sequencing profiles of ESCC patients, and to develop a gene-expression signature for identifying LN metastasis. The robustness of this panel was assessed in 2 independent patient cohorts (n = 56 and 224).

RESULTS

We initially prioritized a 16-gene signature out of the total 20,531 mRNAs. The model estimated by these 16 genes discriminated LN status with an area under the curve (AUC) of 0.77 [95% confidence interval (95% CI), 0.68-0.87, 5-fold cross-validation]. Subsequently, a reduced and optimized 5-gene panel was trained in a clinical cohort, which effectively distinguished ESCC patients with LN metastasis (cohort-1: AUC, 0.74; 95% CI, 0.58-0.89; cohort-2, T1-T2: AUC, 0.74; 95% CI, 0.63-0.86), and was significantly superior to preoperative computed tomography (AUC, 0.61; 95% CI, 0.50-0.72). Furthermore, a combination signature comprising of the 5-gene panel together with the lymphatic vessel invasion (LVI) and venous invasion (VI) demonstrated a significantly improved diagnostic performance compared with individual clinical variables, in both cohorts (cohort-1: AUC, 0.87; 95% CI, 0.78-0.96; cohort-2: AUC, 0.76; 95% CI, 0.65-0.88).

CONCLUSION

Our novel 5-gene panel is a robust diagnostic tool for LN metastasis, especially in early-T stage ESCC patients, with a promising clinical potential.

Up-Regulation of MicroRNA-21 Indicates Poor Prognosis and Promotes Cell Proliferation in Esophageal Squamous Cell Carcinoma via Upregulation of lncRNA SNHG1

Introduction

MicroRNA-21 (miRNA-21) and lncRNA SNHG1 (small nucleolar RNA host gene 1) are known to be aberrantly upregulated and promote tumor progression in various cancers. Nevertheless, very few studies have determined the roles of tissue and circulating miRNA-21 and SNHG1 in ESCC patients. Particularly, knowledge about the characteristics of miRNA-21 and SNHG1 expression and their correlations with survival rates, as well as their interaction with each other remains inadequate in ESCC.

Methods

Thse expression level of miRNA-21 and SNHG1 of tissues, serum and cell lines were detected by qRT-PCR, and the characteristics of their expression and clinicopathology were analyzed. Then, the diagnostic and prognosis value of serum and tissue miRNA-21 and SNHG1 were evaluated, respectively. In addition, the interaction with each other between miRNA-21 and SNHG1, as well as the effect on ESCC cell proliferation were further clarified.

Results

The expression level of miRNA-21 and SNHG1 are significantly upregulated in tissues, serum and cell lines of ESCC, and tissue miRNA-21 and SNHG1 significantly correlates with lymph node metastasis, TNM stage, tumor size, and poor overall survival in ESCC patients. The receiver operating characteristic (ROC) curves show that areas under the ROC curve (AUC) for serum miRNA-21 and SNHG1 are 0.928 and 0.850, respectively. Pearson correlation coefficient indicated that the expression levels of miRNA-21 and SNHG1 in frozen cancerous tissues are significantly associated with their respective serum levels. Further, Cox univariate and multivariate analyses reveal that miRNA-21 and SNHG1 are independent prognostic factors for overall survival (OS) and disease-free survival (DFS) in ESCC patients. In addition, our in vitro data revealed a novel regulatory pathway, in which miRNA-21 is probably a unidirectional upstream positive regulator of SNHG1 in ESCC cells, and the interaction between miRNA-21 and SNHG1 plays an important role in the proliferation of ESCC cells.

Discussion

In summary, our data show that SNHG1 may be a novel downstream target of miRNA-21 and not vice versa in ESCC cells and contributes significantly toward the proliferation of ESCC cells. These findings suggest that miRNA-21 and SNHG1 may serve as potential diagnostic, prognostic biomarkers and therapeutic targets for ESCC patients.

Growth Differentiation Factor 15 Promotes Progression of Esophageal Squamous Cell Carcinoma via TGF-β Type II Receptor Activation

OBJECTIVES

Growth differentiation factor 15 (GDF15), which is derived from tumor-associated macrophages (TAM) and cancer cells, promotes progression of esophageal squamous cell carcinomas (ESCC). However, its role in the ESCC microenvironment remains unclear. Here, we examined the effects of GDF15 on ESCC cell lines and tissues.

METHODS

Western blotting, MTS, and Transwell migration/invasion assays were used to evaluate cell signaling, proliferation, and migration/invasion, respectively, in ESCC cell lines treated with recombinant human GDF15 (rhGDF15). ESCC cell lines were administered a TGF-βRI/II inhibitor (LY2109761), small interfering RNA against TGF-β type II receptor (TGF-βRII), or neutralizing antibody against TGF-βRII to study the role of TGF-βRII in mediating the effects of rhGDF15. The localization of GDF15 and TGF-βRII in ESCC cell lines was observed by immunofluorescence. TGF-βRII expression in ESCC tissues was analyzed by immunohistochemistry, and the relationship between clinicopathological factors and prognosis in ESCC patients was evaluated.

RESULTS

rhGDF15 increased levels of phosphorylated Akt, Erk1/2, and TGF-βRII in ESCC cell lines. Inhibition/knockdown of TGF-βRII suppressed rhGDF15-induced activation of Akt and Erk1/2 and enhancement of cellular proliferation, migration, and invasion. Immunofluorescence revealed that TGF-βRII and GDF15 were colocalized in ESCC cell lines. High TGF-βRII expression in ESCC tissues, as determined by immunohistochemistry, correlated with depth of invasion and increased number of infiltrating TAMs. ESCC patients with high TGF-βRII expression showed a tendency toward poor prognosis.

CONCLUSIONS

GDF15 promotes ESCC progression by increasing cellular proliferation, migration, and invasion via TGF-βRII signaling.

PTK7 promotes the malignant properties of cancer stem-like cells in esophageal squamous cell lines

This study was performed to investigate the role of PTK7 in esophageal squamous cell carcinoma (ESCC) stem-like cells (CSCs). PTK7 expression in ESCCs identified by RT-qPCR, and CSC-like cells were isolated from populations of NEC and TE-1 cells. The CSC-like cells were verified by flow cytometric analyses performed using CD34 and CD133 antibodies, and RT-qPCR and western blot assays were used to examine the self-renewal capability of CSC-like cells. CSC-like cells treated with PTK7 siRNA or a P53-specific inhibitor (PFTα) were analyzed for their sphere formation capacity and their apoptosis and migration/invasion capabilities by sphere formation, flow cytometry, and transwell assay, respectively. Their levels of P53, MKK3, and cleaved caspase 3 expression were examined by western blot analysis. Our results revealed that a majority of the isolated CSC-like cells were CD34⁺/CD133⁺ double positive cells. Nango, Sox2, and OCT4 were dramatically increased in the separated CSC-like cells, which had the pluripotency and self-renewal properties of stem cells. Additional, PTK7 was dramatically upregulated in the ESCC tissues and CSC-like cells. An investigation of the function of CSC-like cells revealed that knockdown of PTK7 reduced their sphere formation, promoted apoptosis, and suppressed their migration and invasion abilities, all of which could be significantly reversed by PFTα. Mechanistic studies showed that PFTα could attenuate the upregulation of P53, MKK3, and cleaved caspase 3 expression that was induced by PTK7 knockdown in CSC-like cells. PTK7 increased the malignant behaviors of CSC-like cells derived from ESCC cells by regulating p53. Therefore, this study suggests PTK7 as an underlying target for therapy against ESCC.

Integrin-Linked Kinase Is Involved In the Proliferation and Invasion of Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is an aggressive type of cancer with high mortality rate in China, largely due to its high invasive and metastatic potential. The purposes of this study are to investigate the potential molecular mechanisms behind the aggressive nature of ESCC and search for new prognostic biomarkers. By employing the quantitative proteomic based strategy, we compared the proteomic profile between three ESCC samples and paired adjacent tissues. After bioinformatics analysis, four candidate proteins were validated in thirteen paired patient samples. Further validation of the key candidate, integrin-linked kinase (ILK), was carried out in one hundred patient samples. The specific inhibitor compound 22 (cpd22) was used to assess the influence of ILK to ESCC cell motility and invasiveness by applying wound-healing and transwell assay. Western blot analysis was performed to elucidate the signaling pathways involved in ILK-mediated ESCC invasion. Total 236 proteins were identified by proteomic analysis. Bioinformatics analysis suggested a key role of the collagen/integrin/ILK signaling pathway during ESCC progression. Further validation indicated that ILK is overexpressed in ESCC tissues and is correlated with poor patient prognosis. Inhibition of ILK kinase activity suppresses proliferation and blocks invasion and migration of ESCC cells. Signaling pathway analysis revealed that ILK regulates AKT phosphorylation on Ser473 but not GSK-3β on Ser9 to promote proliferation and motility of ESCC cells. In conclusion, our results indicated that ILK may play a crucial role in ESCC invasion and metastasis and may serve as a prognostic biomarker and therapeutic target for ESCC.

SOX2OT, a novel tumor-related long non-coding RNA

SOX2OT is a long non-coding RNA that is highly expressed in embryonic stem cells. The SOX2OT gene is comprised of 10 exons and more than two transcription start sites. Dysregulation of SOX2OT is observed in various tumors, including lung cancer, gastric cancer, esophageal cancer, breast cancer, hepatocellular carcinoma, ovarian cancer, pancreatic ductal adenocarcinoma, laryngeal squamous cell carcinoma, cholangiocarcinoma, osteosarcoma, nasopharyngeal carcinoma, and glioblastoma, wherein it typically functions as an oncogene and possibly as a tumor suppressor gene. The mechanisms underlying the effects of SOX2OT are complex and involve multiple factors and signaling pathways. In this review, we describe the current evidence regarding the role and potential clinical utility of SOX2OT in human cancers.

Combination of the natural compound Periplocin and TRAIL induce esophageal squamous cell carcinoma apoptosis in vitro and in vivo: Implication in anticancer therapy

BACKGROUND

Esophageal cancer is one of the most common malignant tumors in the world. With currently available therapies, only 20% ~ 30% patients can survive this disease for more than 5 years. TRAIL, a natural ligand for death receptors that can induce the apoptosis of cancer cells, has been explored as a therapeutic agent for cancers, but it has been reported that many cancer cells are resistant to TRAIL, limiting the potential clinical use of TRAIL as a cancer therapy. Meanwhile, Periplocin (CPP), a natural compound from dry root of Periploca sepium Bge, has been studied for its anti-cancer activity in a variety of cancers. It is not clear whether CPP and TRAIL can have activity on esophageal squamous cell carcinoma (ESCC) cells, or whether the combination of these two agents can have synergistic activity.

METHODS

We used MTS assay, flow cytometry and TUNEL assay to detect the effects of CPP alone or in combination with TRAIL on ESCC cells. The mechanism of CPP enhances the activity of TRAIL was analyzed by western blot, dual luciferase reporter gene assay and chromatin immunoprecipitation (ChIP) assay. The anti-tumor effects and the potential toxic side effects of CPP alone or in combination with TRAIL were also evaluated in vivo.

RESULTS

In our studies, we found that CPP alone or in combination with TRAIL could inhibit the proliferation of ESCC cells and induce apoptosis, and we certificated that combination of two agents exert synergized functions. For the first time, we identified FoxP3 as a key transcriptional repressor for both DR4 and DR5. By down-regulating FoxP3, CPP increases the expression of DR4/DR5 and renders ESCC cells much more sensitive to TRAIL. We also showed that CPP reduced the expression of Survivin by inhibiting the activity of Wnt/β-catenin pathway. All these contributed to synergistic activity of CPP and TRAIL on ESCC cells in vitro and in vivo.

CONCLUSION

Our data suggest that CPP and TRAIL could be further explored as potential therapeutic approach for esophageal cancer.

miR-940 inhibits cell proliferation and promotes apoptosis in esophageal squamous cell carcinoma cells and is associated with post-operative prognosis

The present study aimed to examine microRNA (miR)-940 expression in esophageal squamous cell carcinoma (ESCC) tissues and cells, analyze its association with the clinicopathological features and prognosis of patients, and explore the potential underlying mechanisms. miR-940 expression in ESCC cell lines and a normal esophageal cell line was detected using reverse transcription-quantitative (RT-q)PCR. Furthermore, 210 resected ESCC tissue and para-carcinoma tissue specimens were collected, and miR-940 expression in those tissues was detected by RT-qPCR. In addition, the association of miR-940 with the clinicopathological features and prognosis of patients was analyzed. In an in vitro experiment, miR-940 mimics were transduced into ESCC cells by the liposome method. An MTT assay was used to detect the effect of miR-940 on the viability of ESCC cells. The influence of miR-940 on the cell cycle and apoptotic rate of ESCC cells was detected by flow cytometry. The present results indicated that the expression levels of miR-940 in human ESCC tissues and cell lines were markedly downregulated, and that low expression of miR-940 in ESCC tissues was significantly associated with a poor degree of differentiation, positive lymph node metastasis and advanced clinical stage. Kaplan-Meier survival analysis suggested that low miR-940 expression was associated with poor prognosis. Cox regression analysis revealed that lymph node metastasis, clinical stage and miR-940 expression were independent risk factors affecting the prognosis of patients. Overexpression of miR-940 in ESCC cells markedly reduced the cell viability, blocked the cell cycle at G0/G1 phase and promoted cell apoptosis. These results suggest that miR-940 is downregulated in ESCC, which is linked to the occurrence and progression of ESCC. Conversely, overexpression of miR-940 reduced the cell viability and promoted apoptosis of ESCC cells. Therefore, miR-940 may be a promising novel prognostic marker and anti-cancer target in ESCC.

HERES, a lncRNA that regulates canonical and noncanonical Wnt signaling pathways via interaction with EZH2

Wnt signaling through both canonical and noncanonical pathways plays a core role in development. Dysregulation of these pathways often causes cancer development and progression. Although the pathways independently contribute to the core processes, a regulatory molecule that commonly activates both of them has not yet been reported. Here, we describe a long noncoding RNA (lncRNA), HERES, that epigenetically regulates both canonical and noncanonical Wnt signaling pathways in esophageal squamous cell carcinoma (ESCC). For this study, we performed RNA-seq analysis on Korean ESCC patients and validated these results on a larger ESCC cohort to identify lncRNAs commonly dysregulated in ESCCs. Six of the dysregulated lncRNAs were significantly associated with the clinical outcomes of ESCC patients and defined 4 ESCC subclasses with different prognoses. HERES reduction repressed cell proliferation, migration, invasion, and colony formation in ESCC cell lines and tumor growth in xenograft models. HERES appears to be a transacting factor that regulates CACNA2D3, SFRP2, and CXXC4 simultaneously to activate Wnt signaling pathways through an interaction with EZH2 via its G-quadruple structure-like motif. Our results suggest that HERES holds substantial potential as a therapeutic target for ESCC and probably other cancers caused by defects in Wnt signaling pathways.