A retrospective review of the prognostic value of ALDH-1, Bmi-1 and Nanog stem cell markers in esophageal squamous cell carcinoma

Cancer stem cells: a target for overcoming therapeutic resistance and relapse

Cancer stem cells (CSCs) are a small subset of cells in cancers that are thought to initiate tumorous transformation and promote metastasis, recurrence, and resistance to treatment. Growing evidence has revealed the existence of CSCs in various types of cancers and suggested that CSCs differentiate into diverse lineage cells that contribute to tumor progression. We may be able to overcome the limitations of cancer treatment with a comprehensive understanding of the biological features and mechanisms underlying therapeutic resistance in CSCs. This review provides an overview of the properties, biomarkers, and mechanisms of resistance shown by CSCs. Recent findings on metabolic features, especially fatty acid metabolism and ferroptosis in CSCs, are highlighted, along with promising targeting strategies. Targeting CSCs is a potential treatment plan to conquer cancer and prevent resistance and relapse in cancer treatment.

High NANOG expression correlates with worse patients' survival in esophageal adenocarcinoma

BACKGROUND

Patients diagnosed with esophageal cancer demonstrate a low overall survival even despite the established multimodal therapy as the current standard of care. Therefore, further biomarkers for patients with high-risk and additional therapy options are needed. NANOG is a transcription factor, which can be found in stem cells and is known to support tumorigenesis.

METHODS

Six hundred sixty patients with esophageal adenocarcinoma, who were operated at the University of Cologne with a curative intent, were included. Immunohistochemical stainings for NANOG were performed. The study population was divided into NANOG-positive and -negative subgroups.

RESULTS

Positive NANOG expression correlates significantly with worse overall survival (p = 0.002) and could be confirmed as an independent risk factor for worse patient survival in multivariate analysis (HR = 1.40, 95%CI = 1.09-1.80, p = 0.006). This effect could be detected in the subgroup of primarily operated patients, but not in patients after neoadjuvant therapy.

CONCLUSIONS

We describe a NANOG-positive subgroup of patients with esophageal cancer, who exhibit worse overall survival in a large patient cohort. This discovery suggests the potential use of NANOG as a biomarker for both intensified therapy and stricter follow-up regimes. Additionally, NANOG-positive stem cell-like cancer cells could be used as a new antitumoral treatment target if validated in mechanistic and clinical studies.

Elevation of fatty acid desaturase 2 in esophageal adenocarcinoma increases polyunsaturated lipids and may exacerbate bile acid-induced DNA damage

Background

The risk of esophageal adenocarcinoma (EAC) is associated with gastro‐esophageal reflux disease (GERD) and obesity. Lipid metabolism‐targeted therapies decrease the risk of progressing from Barrett's esophagus (BE) to EAC, but the precise lipid metabolic changes and their roles in genotoxicity during EAC development are yet to be established.

Methods

Esophageal biopsies from the normal epithelium (NE), BE, and EAC, were analyzed using concurrent lipidomics and proteomics (n = 30) followed by orthogonal validation on independent samples using RNAseq transcriptomics (n = 22) and immunohistochemistry (IHC, n = 80). The EAC cell line FLO‐1 was treated with FADS2 selective inhibitor SC26196, and/or bile acid cocktail, followed by immunofluorescence staining for γH2AX.

Results

Metabolism‐focused Reactome analysis of the proteomics data revealed enrichment of fatty acid metabolism, ketone body metabolism, and biosynthesis of specialized pro‐resolving mediators in EAC pathogenesis. Lipidomics revealed progressive alterations (NE‐BE‐EAC) in glycerophospholipid synthesis with decreasing triglycerides and increasing phosphatidylcholine and phosphatidylethanolamine, and sphingolipid synthesis with decreasing dihydroceramide and increasing ceramides. Furthermore, a progressive increase in lipids with C20 fatty acids and polyunsaturated lipids with ≥4 double bonds were also observed. Integration with transcriptome data identified candidate enzymes for IHC validation: Δ4‐Desaturase, Sphingolipid 1 (DEGS1) which desaturates dihydroceramide to ceramide, and Δ5 and Δ6‐Desaturases (fatty acid desaturases, FADS1 and FADS2), responsible for polyunsaturation. All three enzymes showed significant increases from BE through dysplasia to EAC, but transcript levels of DEGS1 were decreased suggesting post‐translational regulation. Finally, the FADS2 selective inhibitor SC26196 significantly reduced polyunsaturated lipids with three and four double bonds and reduced bile acid‐induced DNA double‐strand breaks in FLO‐1 cells in vitro.

Conclusions

Integrated multiomics revealed sphingolipid and phospholipid metabolism rewiring during EAC development. FADS2 inhibition and reduction of the high polyunsaturated lipids effectively protected EAC cells from bile acid‐induced DNA damage in vitro, potentially through reduced lipid peroxidation.

Cancer stem-like cells contribute to paclitaxel resistance in esophageal squamous cell carcinoma

OBJECTIVE

To examine the role of esophageal squamous cell carcinoma (ESCC) stem cells in paclitaxel resistance through the molecular characterization of ESCC stem cells.

METHODS

A resistant cell line (RR-ECl09) of cells were established using intermittent induction and time increments of high-dose paclitaxel in a human esophageal squamous cell carcinoma line (EC109). The multidrug resistance of RR-ECl09 cells to anticancer agents was evaluated by MTT assay. The RR-EC109 and EC109 cells were used for sphere formation assays, clonogenicity assays, stem cell gene expression, and the expression of epithelial-mesenchymal transition markers.

RESULTS

The RR-EC109 cells were established over 7 months. RR-ECl09 cells had 67.258 fold resistance to paclitaxel. The percentage of sphere formation and clone proliferation ability of RR-EC109 cells was higher than that of EC109 cells (P < 0.05). The amount of side population cells in RR-EC109 cells was higher than that of EC109 cells (P < 0.05). RR-EC109 cells produced more mRNA for Bmi1, Nanog, Oct4, Sox2, ABCG2, Nestin, and Ki-67 than EC109 cells (P < 0.05). E-cadherin expression was lower in RR-EC109 cells than in EC109 cells, while N-cadherin, Snail, and Twist expressions were higher in RR-EC109 cells than in EC109 cells (P < 0.05).

CONCLUSIONS

Cancer stem cell (CSC)-like cells exist among paclitaxel-resistant cells in ESCC and may play a role in ESCC drug resistance.

Comprehensive Analysis of Aldehyde Dehydrogenases (ALDHs) and Its Significant Role in Hepatocellular Carcinoma

Oxidative DNA damage is closely related to the occurrence and progression of cancer. Oxidative stress plays an important role in alcohol-induced hepatocellular carcinoma (HCC). Aldehyde dehydrogenase (ALDH) is a family of enzymes that plays an essential role in the reducing oxidative damage. However, how ALDHs family affects alcohol-related HCC remains obscure. We aimed to explore the correlation between the differential expression of ALDHs in patients with HCC and pathological features, as well as the relationship between ALDHs and prognosis, and finally analyze the possible mechanism of ALDHs in targeted therapy of HCC. The data of HCC were downloaded from The Cancer Genome Atlas (TCGA) database. This research explored the expression and prognostic values of ALDHs in HCC using Oncomine, UALCAN, Human Protein Atlas, cBioPortal, Kaplan-Meier plotter, GeneMANIA, Tumor Immune Estimation Resource, GEPIA databases, and WebGestalt. Low mRNA and protein expressions of ALDHs were found to be significantly associated with tumor grade and clinical cancer stages in HCC patients. In particular, the loss of ALDH expression is more obvious in Asians, and its effect on prognosis is far more significant than that in the White race. Our findings play an important role in the study of prognostic markers and anti-liver cancer therapeutic targets for the members of the ALDHs family, especially in patients with liver cancer in Asia.

Prognostic value of stem cell markers in esophageal and esophagogastric junction cancer: a meta-analysis

Background: Esophageal cancer is an aggressive tumor, with poor prognosis and low survival rates. Although diagnosis and treatment have improved considerably, more efficient prognostic factors are urgently needed to prevent postoperative recurrence and metastasis. Cancer stem cells are key players in tumor progression and several studies have investigated the association between the expression of stemness genes and clinical outcome. However, the prognostic value of stemness markers in esophageal cancer remains controversial. We identified six factors involved in angiogenesis, anti-apoptosis and self-renewal that have been associated to poor prognosis in other types of cancer. We conducted a review of the literature and a meta-analysis to assess their potential prognostic role in this malignancy.

Material and Methods: The database of PMC, PubMed, Web of Science, Embase and The Cochrane Library were searched to investigate the association between CD34, CD133, Nucleostemin, OCT-4, NANOG and CD90, and the survival of patients affected by esophageal squamous cell carcinoma or esophageal adenocarcinoma. Among the 615 eligible studies, a total of 19 articles (including 1586 patients) met the inclusion criteria for the meta-analysis, and the pooled hazard ratio and 95% confidence intervals were calculated.

Results: Data showed that high expression of CD34 (HR 2.10; 95%CI 1.41-3.14; I²=56%; p=0.0003), CD133 (HR 1.91; 95%CI 1.15-3.19; I²=55%; p=0.01) and Nucleostemin (HR 2.97; 95%CI 1.11-7.98; I²=0%; p=0.03) were associated with poor prognosis in patients affected by esophageal cancer. The expression of NANOG and OCT-4 showed no significant association with survival of patients, whereas no study involving CD90 was included in this meta-analysis. Conclusion: CD34, CD133 and Nucleostemin might represent useful prognostic markers in patients affected by esophageal cancer.

Tumoral Expression of CD166 in Human Esophageal Squamous Cell Carcinoma: Implications for Cancer Progression and Prognosis

Accumulating data showed that cancer stem cells (CSCs) identified by cell surface markers contribute to the initiation, progression, and prognosis of human cancers. In this study, the expression of CSC candidates CD166, CD44, and Lgr5 in 65 cases of esophageal squamous cell carcinoma (ESCC) and 16 cases of control esophageal tissues were examined with immunohistochemistry (IHC). The correlation between tumoral expression levels of these CSC candidates and clinicopathological variables was analyzed. IHC results showed that the expression of CD166 in esophageal control tissues was completely negative, but it was in 87.69% (57/65) ESCC tissues. The expression of CD44 and Lgr5 did not differ between esophageal control tissues and ESCC tissues (p > 0.05). In addition, there were not correlations found among the expression levels of CD166, CD44, and Lgr5 in ESCC tissues. Clinicopathological analysis revealed that the tumoral expression level of CD166 correlated with lymph node involvement and TNM staging in patients with ESCC, and lower tumoral expression of CD44 was found in patients with advanced TNM staging. Kaplan-Meier survival curves suggested that expression level of CD166 appeared to have a negative impact on overall survival rate after surgery in patients with ESCC. Such impact was not found in other two CSC candidates. The authors therefore conclude that CD166 is a potential prognostic biomarker and correlates with advanced progression features in patients with ESCC.

TRIB3 confers radiotherapy resistance in esophageal squamous cell carcinoma by stabilizing TAZ

Radioresistance becomes the major obstacle to reduce tumor recurrence and improve prognosis in the treatment of esophageal squamous cell carcinoma (ESCC). Thus new strategies for radioresistant ESCC are urgently needed. Herein, we reported that tribbles pseudokinase 3 (TRIB3) serves as a key regulator of radioresistance in ESCC. TRIB3 is overexpressed in ESCC tissues and cell lines. High expression of TRIB3 significantly correlates with poor radiotherapy response and prognosis in ESCC patients. Upregulation of TRIB3 in ESCC cells conferred radioresistance in vitro and in vivo by interacting with TAZ thus impeding β-TrCP-mediated TAZ ubiquitination and degradation. Conversely, silencing TRIB3 sensitized ESCC cells to ionizing radiation. More importantly, TRIB3 was significantly correlated with TAZ activation in ESCC biopsies, and patients with high expression of both TRIB3 and TAZ suffered the worst radiotherapy response and survival. Our study uncovers the critical mechanism of ESCC resistance to radiotherapy, and provides a new pharmacological opportunity for developing a mechanism-based strategy to eliminate radioresistant ESCC in clinical practice.

Detention and Identification of Cancer Stem Cells in Esophageal Squamous Cell Carcinoma

Cancer stem cells (CSCs) are a small subpopulation of cells associated with cancer initiation, progression, metastasis, therapy resistant, and recurrence. In esophageal squamous cell carcinoma (ESCC), several cell surface and intracellular markers, for example, CD44, ALDH, Pygo2, MAML1, Twist1, Musashi1, side population (SP), CD271, and CD90, have been proposed to identify CSCs. In addition, stem cell markers such as ALDH1, HIWI, Oct3/4, ABCG2, SOX2, SALL4, BMI-1, NANOG, CD133, and podoplanin were associated with pathological stages of cancer, cancer recurrence, prognosis, and therapy resistance of patients with ESCC. Identification and isolation of CSCs could play an important part of improved cancer management regime in ESCC. Furthermore, CSCs may be used as the predictive tool for chemoradiotherapy response in ESCC. Different methods such as in vitro functional assays, cell sorting using various intracellular, and cell surface markers and xenotransplantation techniques are frequently used for the identification and isolation of CSCs in different cancers, including ESCC. However, none of these methods solely can guarantee complete isolation of CSC population. Therefore, a combination of methods is used for reliable detection and isolation of CSCs. Herein, we describe the identification and isolation of CSCs from ESCC cells by cell sorting after Hoechst 33342 staining followed by in vitro functional assays and in vivo mouse xenotransplantation techniques.

Prognostic Significance of ALDH1, Bmi1, and OCT4 Expression in Oral Epithelial Dysplasia and Oral Squamous Cell Carcinoma

BACKGROUND

Increasing evidence suggests the involvement of cancer stem cells (CSCs) in both oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC). Among the various CSC markers, aldehyde dehydrogenase (ALDH) 1, B cell-specific Moloney murine leukaemia virus integration site 1 (Bmi1), and octamer-binding protein 4 (OCT4) have been noted to increase in OSCC. The aim of the study was to analyze ALDH1, Bmi1, and OCT4 expression in OED and OSCC with clinicopathologic correlation and survival analysis.

METHODS

A total of 40 cases each of OED and OSCC were retrieved from departmental archives. Expression of ALDH1, Bmi1, and OCT4 was analyzed using immunohistochemistry and was correlated with clinicopathological parameters. A follow-up ranging from 6 to 52 months was considered for Kaplan-Meier survival analysis. The log-rank test was performed to analyze significant difference in survival rates.

RESULTS

The expression levels of ALDH1, Bmi1, and OCT4 increased significantly from OED through OSCC (P < .05). The expression of ALDH1 and OCT4 showed a significant correlation with lymph node metastasis. Positive cases of ALDH1 showed a significantly reduced survival rate compared to cases showing negative expression. Kaplan-Meier survival analysis showed a significant reduction of survival rate (P = .00) in patients showing a positive expression for all the 3 markers.

CONCLUSION

ALDH1 and OCT4 could be used as individual prognostic markers for assessing prognosis. ALDH1, Bmi1, and OCT4 could be used as a collective panel of markers to enable surgeons in predicting the prognosis of patients and thereby carry out prompt follow-up for such cases.

The Emerging Role of NANOG as an Early Cancer Risk Biomarker in Patients with Oral Potentially Malignant Disorders

NANOG, a key regulator of pluripotency and self-renewal in embryonic and adult stem cells, is frequently overexpressed in multiple cancers, including oral squamous cell carcinoma (OSCC). It has been frequently associated with poor outcomes in epithelial cancers, and recently implicated in laryngeal tumorigenesis. On this basis, we investigated the role of NANOG protein expression as an early cancer risk biomarker in oral potentially malignant disorders (OPMD), and the impact on prognosis and disease outcomes in OSCC patients. NANOG expression was evaluated by immunohistochemistry in 55 patients with oral epithelial dysplasia, and 125 OSCC patients. Correlations with clinical and follow-up data were assessed. Nuclear NANOG expression was detected in 2 (3.6%) and cytoplasmic NANOG expression in 9 (16.4%) oral dysplasias. NANOG expression increased with the grade of dysplasia. Cytoplasmic NANOG expression and the histopathological grading were significantly correlated with oral cancer risk, although dysplasia grading was the only significant independent predictor of oral cancer development in multivariate analyses. Cytoplasmic NANOG expression was also detected in 39 (31%) OSCC samples. Positive NANOG expression was significantly associated with tobacco and alcohol consumption, and was more frequent in pN0 tumors, early I-II stages. These data unveil the clinical relevance of NANOG in early stages of OSCC tumorigenesis rather than in advanced neoplastic disease. NANOG expression emerges as an early predictor of oral cancer risk in patients with OPMD.

Identification of Cancer Stem Cell Molecular Markers and Effects of hsa-miR-21-3p on Stemness in Esophageal Squamous Cell Carcinoma

Cancer stem cells (CSCs) are closely related to tumor resistance and tumor recurrence in esophageal squamous cell carcinoma (ESCC). The lack of specific biomarkers to identify and isolate CSCs has led to the slow progression of research on CSCs in ESCC. Here, we established a method to identify and isolate CSCs in ESCC using fluorescence-activated cell sorting with combined surface biomarkers including CD71, CD271, and CD338. CD71⁻/CD271⁺/CD338⁺ subpopulation cells possessed more stem cell properties in proliferation, self-renewal, differentiation, metastasis, drug resistance, and tumorigenesis. We further explored possible roles that microRNAs played in stem cells. Using microarrays, we identified that has-miR-21-3p was highly expressed in positive sorted cells, and further functional and Luciferase reporter assays verified that has-miR-21-3p promoted proliferation and anti-apoptosis by regulating TRAF4. We further analyzed the relationship between hsa-miR-21-3p and ESCC in 137 patients with ESCC. Statistical analysis showed that up-regulation of hsa-miR-21-3p was associated with a high risk of ESCC. Collectively, we identified surface biomarkers of stem cells in esophageal squamous cell carcinoma, and discovered thathsa-miR-21-3p may be involved in stemness maintenance by regulating TRAF4.

Clinicopathological and Prognostic Significance of Expression of B-Cell-Specific Moloney Murine Leukemia Virus Insertion Site 1 (BMI-1) Gene and Protein in Gastrointestinal Stromal Tumors

BACKGROUND Gastrointestinal stromal tumor (GIST) is an uncommon visceral sarcoma that arises predominantly in the gastrointestinal tract. Since GISTs are encountered infrequently and inflexible to traditional therapy, the aim of the present study was to explore the correlation of B-cell-specific Moloney murine leukemia virus insertion site 1 (BMI-1) mRNA and BMI-1 protein levels with the clinicopathological characteristics and prognosis significance of GISTs. MATERIAL AND METHODS GIST tissues and normal tissues were collected from 156 patients who had undergone surgical treatment. RT-qPCR and immunohistochemistry were used to measure the BMI-1 mRNA and protein levels in GIST tissues and normal tissues. Univariate survival analysis was used for determination of the factors that affect prognosis of GIST patients. Cox proportional hazards model was plotted to determine the independent risk factors for prognosis of GIST patients. RESULTS The BMI-1 mRNA and protein levels in GIST tissues were higher than those in normal tissues. BMI-1 mRNA and positive protein levels were correlated with the National Institutes of Health (NIH) risk grade, tumor diameter and infiltration, and metastasis. There was a short survival period for the patients with a positive protein level and a high mRNA level of BMI-1. The site of primary tumor, tumor diameter, NIH risk grade, infiltration, and metastasis, as well as BMI-1 mRNA and protein levels were independent risk factors for prognosis of GIST patients. CONCLUSIONS Taken together, these findings suggest there might be a relationship between BMI-1 mRNA and protein levels, and clinicopathological characteristics, including NIH risk grade, tumor size as well as infiltration and metastasis, of GIST patients. In addition, BMI-1 mRNA and protein levels were identified as independent risk factors for prognosis of GIST patients.

Prognostic significance of NANOG expression in solid tumors: a meta-analysis

Purpose

NANOG is a tumor marker and indicates poor prognosis in various neoplasms; however, the evidence is controversial. This meta-analysis investigated the association of NANOG expression and clinicopathological features, and it impact on survival of patients with malignant tumors.

Methods

Studies published through May 31, 2018 were retrieved from PubMed, Web of Science, Embase, and the China National Knowledge Infrastructure. Two researchers independently screened the content and quality of studies and extracted data. Correlations of NANOG expression, clinicopathological variables, and survival were analyzed and the combined odds ratios (ORs) and hazard ratios (HRs) with 95% confidence intervals (95% CIs) were calculated.

Results

Thirty-three articles including 35 data sets of 3,959 patients were analyzed. Overall, elevated NANOG expression was associated with poor overall survival (HR = 2.19; 95% CI: 1.87–2.58, P<0.001) and poor disease-free survival (HR = 2.21, 95% CI: 1.54–3.18, P<0.001). Subgroup analysis found that NANOG expression was associated with worse overall survival in non–small cell lung (HR = 1.87; 95% CI: 1.26–2.76, P = 0.002), head and neck (HR = 2.29; 95% CI: 1.75–3.02, P<0.001), and digestive system (HR = 2.38; 95% CI: 1.95–2.91, P<0.001) cancers. Moreover, we found that high NANOG expression was associated with poor tumor differentiation (OR = 2.63; 95% CI: 1.59–4.55, P = 0.001), lymph node metastasis (OR = 2.59; 95% CI: 1.50–4.47, P = 0.001), advanced TNM stage (OR = 2.22; 95% CI: 1.42–3.45, P<0.001), and T stage (OR = 0.44; 95% CI: 0.20–0.93, P = 0.031).

Conclusion

The evidence supports NANOG as a tumor biomarker to guide clinical management and indicate prognosis. Additional studies are needed to further validate these results.

Clinicopathological significance of Bmi-1 overexpression in esophageal cancer: a meta-analysis

AIM

The clinicopathological effects of Bmi-1 expression in esophageal cancer remain widely disputed. Our aim was to clarify this relationship.

METHODS

Available studies were retrieved from diverse databases. Review Manager 5.3 and Stata 12.0 software were used to identify correlations between Bmi-1 expression and the clinicopathological features of esophageal cancer.

RESULTS

From 16 studies, 1523 esophageal cancer patients were analyzed. Meta-analysis demonstrated that Bmi-1 overexpression was associated with differentiation (p = 0.03), tumor/node/metastasis stage (p = 0.02), depth of invasion (p = 0.0006) and lymph node metastasis (p = 0.008).

CONCLUSION

The expression of Bmi-1 is associated with the progression and invasion of esophageal cancer.

MicroRNA-17 is downregulated in esophageal adenocarcinoma cancer stem-like cells and promotes a radioresistant phenotype

Resistance to neoadjuvant chemoradiation therapy (CRT) remains a critical barrier to the effective treatment of esophageal adenocarcinoma (EAC). Cancer stem-like cells (CSCs) are a distinct subpopulation of cells implicated in the resistance of tumors to anti-cancer therapy. However, their role in the resistance of EAC to CRT is largely unknown. In this study, using a novel in vitro isogenic model of radioresistant EAC, we demonstrate that radioresistant EAC cells have enhanced tumorigenicity in vivo, increased expression of CSC-associated markers and enhanced holoclone forming ability. Further investigation identified a subpopulation of cells that are characterised by high aldehyde dehydrogenase (ALDH) activity, enhanced radioresistance and decreased expression of miR-17-5p. In vitro, miR-17-5p was demonstrated to significantly sensitise radioresistant cells to X-ray radiation and promoted the repression of genes with miR-17-5p binding sites, such as C6orf120. In vivo, miR-17-5p was significantly decreased, whilst C6orf120 was significantly increased, in pre-treatment EAC tumour samples from patients who demonstrated a poor response to neoadjuvant CRT. This study sheds novel insights into the role of CSCs in the resistance of EAC to CRT and highlights miR-17-5p as a potential biomarker of CRT sensitivity and novel therapeutic target in treatment resistant EAC.

Nano Let‑7b sensitization of eliminating esophageal cancer stem‑like cells is dependent on blockade of Wnt activation of symmetric division

The poor therapy response and poor prognosis of esophageal cancer has made it one of the most malignant carcinoma, and the complicated multidisciplinary treatment failed to achieve a long-term disease-free survival. To diagnose esophageal cancer at an earlier stage, and to improve the effect of anticancer therapy would improve the therapeutic efficacy. After retrospective analysis of the cancer samples of patients who received esophagectomy, we found the relevance between ratio of either ALDH1 or CD133-positive cancer stem cells and 2-year recurrence. Higher ratios of cancer stem cells indicated later clinical stages, and Wnt signaling activation was more frequent in later esophageal carcinoma. Further in bench studies, we explored the suppressive roles and the mechanisms involved in Let‑7 on self-renewal in ECA‑109 and ECA‑9706 esophageal cancer stem cells. Isolated cancer stem cells naturally divide symmetrically and are therapy resistant. Therapy of fluorouracil and docetaxel both enriched the stem cells, proving the resistant characteristics of cancer stem cells. Wnt activation stimulated more symmetric division of stem cells, resulting in self-renewal promotion, which could be blocked by Let‑7 overexpression. Furthermore, enforced Let‑7 sensitized the stem cells to chemotherapies in a Wnt pathway inhibition-dependent manner, contributing to Let‑7 sensitization of chemotherapeutic response. Wnt activation weakened the suppressive Let‑7b through the sponge functions of CCAT-1, forming the negative feedback loop of Let‑7b/Wnt/CCAT1. These results identified the crucial participation of stem cells in esophageal cancer occurrence and progression as the potent indicator, and also indicate the potential powerful agent of Let‑7 nano-particles in treatment of cancer.

Expression and Clinicopathological Significance of Mel-18 and Bmi-1 in Esophageal Squamous Cell Carcinoma

The Polycomb group genes are a general class of regulators that are responsible for maintaining homeotic gene expression throughout cell division. Polycomb group expression plays an important role in oncogenesis of several types of human cancer. Melanoma nuclear protein 18 and B-cell-specific Moloney leukemia virus insert site 1 are key Polycomb group proteins. Studies have shown that melanoma nuclear protein 18 is a potential tumor suppression, and B-cell-specific Moloney leukemia virus insert site 1 is overexpressed in several human malignancies. However, the roles of melanoma nuclear protein 18 and B-cell-specific Moloney leukemia virus insert site 1 in esophageal squamous cell carcinoma are still unclear. In this study, we analyzed the expression levels of melanoma nuclear protein 18 and B-cell-specific Moloney leukemia virus insert site 1 in 89 esophageal cancer tissues and paired normal mucosal tissues using immunohistochemistry, Western blotting, and quantitative real-time polymerase chain reaction analyses. We found that the expression of melanoma nuclear protein 18 in the carcinoma tissues was significantly lower than that in the noncancerous mucosal tissues (P < .05), and B-cell-specific Moloney leukemia virus insert site 1 expression in the carcinoma tissues was significantly higher than that in the noncancerous mucosal tissues (P < .05). In addition, the expression of melanoma nuclear protein 18 was correlated with clinical stage, depth of invasion, and lymph node metastasis (P < .05) but was not correlated with gender, age, degree of differentiation, or disease-free survival (P > .05). B-cell-specific Moloney leukemia virus insert site 1 expression was strongly correlated with the degree of differentiation, clinical stage, and lymph node metastasis (P <.05) but was not correlated with the gender, age, depth of invasion or disease-free survival (P > .05). Moreover, there was a negative correlation between melanoma nuclear protein 18 and B-cell-specific Moloney leukemia virus insert site 1 expressions in esophageal squamous cell carcinoma (P < .05). Our study suggests that melanoma nuclear protein 18 and B-cell-specific Moloney leukemia virus insert site 1 may play a crucial role in esophageal squamous cell carcinoma. Melanoma nuclear protein 18 or B-cell-specific Moloney leukemia virus insert site 1 may be a potential biomarker for diagnosis and prognosis of esophageal squamous cell carcinoma.

Auraptene Attenuates Malignant Properties of Esophageal Stem-Like Cancer Cells

The high incidence of esophageal squamous cell carcinoma has been reported in selected ethnic populations including North of Iran. Low survival rate of esophageal carcinoma is partially due to the presence of stem-like cancer cells with chemotherapy resistance. In the current study, we aimed to determine the effects of auraptene, an interesting dietary coumarin with various biological activities, on malignant properties of stem-like esophageal squamous cell carcinoma, in terms of sensitivity to anticancer drugs and expression of specific markers. To do so, the half maximal inhibitory concentration values of auraptene, cisplatin, paclitaxel, and 5-fluorouracil were determined on esophageal carcinoma cells (KYSE30 cell line). After administrating combinatorial treatments, including nontoxic concentrations of auraptene + cisplatin, paclitaxel, or 5-fluorouracil, sensitivity of cells to chemical drugs and also induced apoptosis were assessed. In addition, quantitative real-time polymerase chain reaction was used to study changes in the expression of tumor suppressor proteins 53 and 21 ( P53 and P21), cluster of differentiation 44 ( CD44), and B cell-specific Moloney murine leukemia virus integration site 1 ( BMI-1) upon treatments. Results of thiazolyl blue assay revealed that auraptene significantly ( P < .05) increased toxicity of cisplatin, paclitaxel, and 5-fluorouracil in KYSE30 cells, specifically 72 hours after treatment. Conducting an apoptosis assay using flow cytometry also confirmed the synergic effects of auraptene. Results of quantitative real-time polymerase chain reaction revealed significant ( P < .05) upregulation of P53 and P21 upon combinatorial treatments and also downregulation of CD44 and BMI-1 after auraptene administration. Current study provided evidence, for the first time, that auraptene attenuates the properties of esophageal stem-like cancer cells through enhancing sensitivity to chemical agents and reducing the expression of CD44 and BMI-1 markers.

Stemness and chemotherapeutic drug resistance induced by EIF5A2 overexpression in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most lethal malignancies of the digestive tract in East Asian countries. Multimodal therapies, including adjuvant chemotherapy and neo-adjuvant chemotherapy, have become more often used for patients with advanced ESCC. However, the chemotherapy effect is often limited by patients' drug resistance. This study demonstrated that EIF5A2 (eukaryotic translation initiation factor 5A2) overexpression induced stemness and chemoresistance in ESCC cells. We showed that EIF5A2 overexpression in ESCC cells resulted in increased chemoresistance to 5-fluorouracil (5-FU), docetaxel and taxol. In contrast, shRNAs suppressing eIF5A2 increased tumor sensitivity to these chemotherapeutic drugs. In addition, EIF5A2 overexpression was correlated with a poorer overall survival in patients with ESCC who underwent taxane-based chemotherapy after esophagectomy (P < 0.05). Based on these results, we suggest that EIF5A2 could be a predictive biomarker for selecting appropriate chemo-treatment for ESCC patients and EIF5A2 inhibitors might be considered as combination therapy to enhance chemosensitivity in patients with ESCC.

Cancer stem cells in oesophageal squamous cell carcinoma: Identification, prognostic and treatment perspectives

Cancer stem cells (CSCs) are a vital subpopulation of cells to target for the treatment of cancers. In oesophageal squamous cell carcinoma (ESCC), there are several markers such as CD44, ALDH, Pygo2, MAML1, Twist1, Musashi1, Side population (SP), CD271 and CD90 that have been proposed to identify the cancer stem cells in individual cancer masses. It has also been demonstrated that stem cell markers like ALDH1, HIWI, Oct3/4, ABCG2, SOX2, SALL4, BMI-1, NANOG, CD133 and podoplanin are associated with patient's prognosis, pathological stages, cancer recurrence and therapy resistance. Finding new cancer stem cell targets or designing drugs to manipulate the known molecular targets in CSCs could be useful for improvements in clinical outcomes of the disease. To conclude, data suggest that CSCs in oesophageal squamous cell carcinoma are related to resistance to therapy and poor prognosis of patients with ESCC. Therefore, innovative insights into CSC biology and CSC-targeted therapies will help to achieve more effective management of patients with oesophageal squamous cell carcinoma.