A novel long noncoding RNA, LOC440173, promotes the progression of esophageal squamous cell carcinoma by modulating the miR-30d-5p/HDAC9 axis and the epithelial-mesenchymal transition

Countless evidence suggests that long noncoding RNAs (lncRNAs) are involved in human malignant cancers, including esophageal squamous cell carcinoma (ESCC), although their exact function remains unclear. In the present study, we aimed to investigate the roles and molecular mechanisms of the lncRNA LOC440173 in ESCC progression. Microarray analysis and quantitative real-time polymerase chain reaction were conducted to measure the expression levels of LOC440173 and miR-30d-5p. The biological function of this lncRNA was investigated using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, clone formation, and transwell assays, as well as flow cytometry and Western blot analysis. The function of LOC440173 was validated in vivo using tumor xenografts. The regulatory network of LOC440173/miR-30d-5p/HDAC9 was established using bioinformatic analysis and verified with dual-luciferase reporter assays, RNA immunoprecipitation assay, and rescue experiments. The expression level of LOC440173 was significantly increased in ESCC tissues and esophageal carcinoma cells. High LOC440173 expression was correlated with histological grade, tumor invasion depth, lymph node metastasis, and TNM stage. Overexpression of LOC440173 promoted esophageal cancer cell proliferation, migration, and invasion, as well as the epithelial-mesenchymal transition (EMT) process in vitro, and facilitated tumor growth in vivo. MicroRNA-30d-5p (miR-30d-5p) was downregulated in ESCC tissues and acted as a direct binding target of LOC440173 during the regulation of HDAC9 expression in esophageal carcinoma cells. In conclusion, LOC440173 exerts a promotive role in ESCC tumorigenesis by targeting the miR-30d-5p/HDAC9 axis and regulating the EMT process. LOC440173 might be a new therapeutic target for the treatment of ESCC.

PBX1 Increases the Radiosensitivity of Oesophageal Squamous Cancer by Targeting of STAT3

The radioresistance of oesophageal squamous cell carcinoma (OSCC) is a critical factor leading to a poor prognosis among patients. The expression of PBX1 is abnormally high in a broad range of human tissues, and this gene plays a key role in tumour proliferation. This research intended to explore the radiosensitization of OSCC by silencing PBX1. The OSCC cell lines KYSE450 and KYSE150 were subjected to PBX1 silencing and/or irradiation (IR). Cell proliferation, colony formation, and apoptosis were tested to evaluate the radiosensitization ability of PBX1 silencing. The levels of STAT3 and p-STAT3 in the OSCC cells were tested by Western blotting. Furthermore, KYSE150 cells with or without PBX1 silencing were xenografted into nude mice with or without radiation exposure. Concomitant PBX1 silencing and IR can obviously suppress growth and enhance radiosensitivity in OSCC cells and xenografts. Moreover, the downregulation of PBX1 inhibits the expression of STAT3 and p-STAT3. The downregulation of PBX1 may increase radiosensitivity in OSCC cells and xenografts via the PBX1/STAT3 pathway. Our findings demonstrate that PBX1 may be a potential target for promoting the effect of radiation therapy in OSCC patients.

MTA1 promotes tumorigenesis and development of esophageal squamous cell carcinoma via activating the MEK/ERK/p90RSK signaling pathway

Metastasis-associated protein 1 (MTA1) is upregulated in multiple malignancies and promotes cancer proliferation and metastasis, but whether and how MTA1 promotes esophageal squamous cell carcinoma (ESCC) tumorigenesis remain unanswered. Here, we established an ESCC model in MTA1 transgenic mice induced by the chemical carcinogen 4-nitroquinoline 1-oxide (4-NQO) and found that MTA1 promotes ESCC tumorigenesis in mice. MTA1 overexpression was observed in ESCC cells and clinical ESCC samples. Overexpressed MTA1 increased colony formation and the invasiveness and migration of ESCC cells, whereas knock down of MTA1 in ESCC cells significantly decreased colony formation, invasion and migration in vitro and inhibited the growth of xenograft tumors in vivo. RNA sequencing (RNA-seq) analysis combined with western blot assays revealed that MTA1 promotes carcinogenesis by enhancing MEK/ERK/p90RSK signaling. The phosphorylation of MEK, ERK and their downstream target p90RSK was significantly decreased after MTA1 knockdown in ESCC cells and was increased in MTA1-overexpressing cells. Moreover, colony formation, invasion and migration potential were dramatically suppressed when cells overexpressing MTA1 were treated with MEK (PD0325901) or ERK (SCH772948) inhibitors. In conclusion, MTA1 plays a pivotal oncogenic role in ESCC tumorigenesis and development through activating the MEK/ERK/p90RSK pathway.

Deoxypodophyllotoxin, a Lignan from Anthriscus sylvestris, Induces Apoptosis and Cell Cycle Arrest by Inhibiting the EGFR Signaling Pathways in Esophageal Squamous Cell Carcinoma Cells

Deoxypodophyllotoxin (DPT) derived from Anthriscus sylvestris (L.) Hoffm has attracted considerable interest in recent years because of its anti-inflammatory, antitumor, and antiviral activity. However, the mechanisms underlying DPT mediated antitumor activity have yet to be fully elucidated in esophageal squamous cell carcinoma (ESCC). We show here that DPT inhibited the kinase activity of epidermal growth factor receptor (EGFR) directly, as well as phosphorylation of its downstream signaling kinases, AKT, GSK-3β, and ERK. We confirmed a direct interaction between DPT and EGFR by pull-down assay using DPT-beads. DPT treatment suppressed ESCC cell viability and colony formation in a time- and dose-dependent manner, as shown by MTT analysis and soft agar assay. DPT also down-regulated cyclin B1 and cdc2 expression to induce G2/M phase arrest of the cell cycle and upregulated p21 and p27 expression. DPT treatment of ESCC cells triggered the release of cytochrome c via loss of mitochondrial membrane potential, thereby inducing apoptosis by upregulation of related proteins. In addition, treatment of KYSE 30 and KYSE 450 cells with DPT increased endoplasmic reticulum stress, reactive oxygen species generation, and multi-caspase activation. Consequently, our results suggest that DPT has the potential to become a new anticancer therapeutic by inhibiting EGFR mediated AKT/ERK signaling pathway in ESCC.

Porphyromonas gingivalis promotes progression of esophageal squamous cell cancer via TGFβ-dependent Smad/YAP/TAZ signaling

Microbial dysbiosis in the upper digestive tract is linked to an increased risk of esophageal squamous cell carcinoma (ESCC). Overabundance of Porphyromonas gingivalis is associated with shorter survival of ESCC patients. We investigated the molecular mechanisms driving aggressive progression of ESCC by P. gingivalis. Intracellular invasion of P. gingivalis potentiated proliferation, migration, invasion, and metastasis abilities of ESCC cells via transforming growth factor-β (TGFβ)-dependent Drosophila mothers against decapentaplegic homologs (Smads)/Yes-associated protein (YAP)/Transcriptional coactivator with PDZ-binding motif (TAZ) activation. Smads/YAP/TAZ/TEA domain transcription factor1 (TEAD1) complex formation was essential to initiate downstream target gene expression, inducing an epithelial-mesenchymal transition (EMT) and stemness features. Furthermore, P. gingivalis augmented secretion and bioactivity of TGFβ through glycoprotein A repetitions predominant (GARP) up-regulation. Accordingly, disruption of either the GARP/TGFβ axis or its activated Smads/YAP/TAZ complex abrogated the tumor-promoting role of P. gingivalis. P. gingivalis signature genes based on its activated effector molecules can efficiently distinguish ESCC patients into low- and high-risk groups. Targeting P. gingivalis or its activated effectors may provide novel insights into clinical management of ESCC.

miR-550a-3/NFIC plays a driving role in esophageal squamous cell cancer cells proliferation and metastasis partly through EMT process

In this study, the functional role of miR-550a-3 and its direct target nuclear factor IC (NFIC) in esophageal squamous cell cancer (ESCC) cells were explored. Differential expression of miR-550a-3 in ESCC tissues was acquired from TCGA database, and Kaplan-Meier method was used to determine the relationship between miR-550a-3 expression and survival time of ESCC patients. Expression level of miR-550a-3 in several ESCC cell lines was measured by qRT-PCR. Two cell lines including Eca109 and JAR were used to perform proliferation, cloning, invasion and migration experiments. Targeted relationship between miR-550a-3 and NFIC was speculated by predication software and confirmed by dual luciferase assay. Additionally, potential relationship between miR-550a-3 and NFIC was analyzed by Spearman rank correlation analysis and western blot. Rescue assays were performed to explore the function of miR-550a-3/NFIC in ESCC cells biological behaviors. Expression levels of key proteins involved in epithelial-to-mesenchymal transition (EMT) process were determined by western blot. By consulting TCGA database, we found that high expression of miR-550a-3 was positively connected with the poor prognosis of patients with ESCC. In addition, overexpression of miR-550a-3 promoted the proliferation, colony formation and metastasis of ESCC cells. Moreover, rescue assays revealed that overexpression of NFIC attenuated the promoting effects of miR-550a-3 on ESCC cells malignant behaviors. While the promoting effects of miR-550a-3 on EMT process were inhibited by NFIC. Our results illustrate the importance of miR-550a-3/NFIC in regulation of ESCC cells growth and metastasis, which could contribute to developing novel target for early diagnosis or neoteric therapeutic target for ESCC.

Tumor immune microenvironment and immune checkpoint inhibitors in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is the main prevalent histological type of esophageal cancer, predominantly constituting 90% of cases worldwide. Despite the development of multidisciplinary therapeutic approaches, its prognosis remains unfavorable. Recently, the development of monoclonal antibodies inhibiting programmed death 1 (PD-1) or programmed death-ligand 1 (PD-L1) has led to marked therapeutic responses among multiple malignancies including ESCC. However, only a few patients achieved clinical benefits due to resistance. Therefore, precise and accurate predictive biomarkers should be identified for personalized immunotherapy in clinical settings. Because the tumor immune microenvironment can potentially influence the patient's response to immune checkpoint inhibitors, tumor immunity, such as PD-L1 expression on tumors, tumor-infiltrating lymphocytes, tumor-associated macrophages, and myeloid-derived suppressor cells, in ESCC should be further investigated. In this review, accumulated evidence regarding the tumor immune microenvironment and immune checkpoint inhibitors in ESCC are summarized.

OP16 induces deadly autophagy and apoptosis of cells by inhibiting Akt in esophageal squamous cell carcinoma

BACKGROUND

OP16, a derivative of the novel ent-kaurene diterpenoid compound separated from Rabdosia rubescens, has been confirmed for its efficacy and safety in the treatment of esophageal squamous cell carcinoma (ESCC) in our previous study. However, the precise mechanisms of tumor lethality mediated by OP16 have not yet been fully characterized.

AIMS

To investigate the effects and molecular mechanism of OP16 on autophagy and apoptosis of ESCC cells.

METHODS

Effects and mechanism of OP16 on autophagy of ESCC cells were first detected by Western blot, immunofluorescence, mRFP-GFP-LC3 adenovirus infection and transmission electron microscope. Next, function of autophagy and apoptosis induced by OP16 on cell death was investigated by flow cytometry and CCK-8 assay. Finally, molecular mechanism of OP16 affecting autophagy and apoptosis of ESCC cells was explored by Western blot.

RESULTS

We demonstrated that OP16 could induce autophagy by promoting the formation of autophagosome and autolysosome, and promote autophagic cell death in ESCC. Furthermore, we also found that OP16 could promote cell apoptosis by activating mitochondria apoptosis pathway in ESCC. Finally, we demonstrated that OP16 affecting autophagy and mitochondria apoptosis pathway was mediated by phosphorylation of Akt.

CONCLUSION

Our data show that OP16 could promote cell death through affecting autophagy and mitochondria apoptosis pathway mediated by Akt in ESCC, which enriches the theoretical mechanism of anti-tumor effects of OP16 and provides a basis for treatment of OP16 on ESCC.

Esophageal Squamous Cell Carcinoma Is Accompanied by Local and Systemic Changes in L-arginine/NO Pathway

The L-arginine/NO pathway holds promise as a source of potential therapy target and biomarker; yet, its status and utility in esophageal squamous cell carcinoma (ESCC) is unclear. We aimed at quantifying pathway metabolites in sera from patients with ESCC (n = 61) and benign conditions (n = 62) using LC-QTOF-MS and enzyme expression in esophageal tumors and matched noncancerous samples (n = 40) using real-time PCR with reference to ESCC pathology and circulating immune/inflammatory mediators, quantified using Luminex xMAP technology. ESCC was associated with elevated systemic arginine and asymmetric dimethylarginine. Citrulline decreased and arginine bioavailability increased along with increasing ESCC advancement. Compared to adjacent tissue, tumors overexpressed ODC1, NOS2, PRMT1, and PRMT5 but had downregulated ARG1, ARG2, and DDAH1. Except for markedly higher NOS2 and lower ODC1 in tumors from M1 patients, the pathology-associated changes in enzyme expression were subtle and present also in noncancerous tissue. Both the local enzyme expression level and systemic metabolite concentration were related to circulating inflammatory and immune mediators, particularly those associated with eosinophils and those promoting viability and self-renewal of cancer stem cells. Metabolic reprogramming in ESCC manifests itself by the altered L-arginine/NO pathway. Upregulation of PRMTs in addition to NOS2 and ODC1 and the pathway link with stemness-promoting cytokines warrants further investigation.

Expression of SIRT1 and survivin correlates with poor prognosis in esophageal squamous cell carcinoma

This study assessed the association of sirtuin type 1 (SIRT1) and survivin expression with the clinicopathological features and survival of esophageal squamous cell carcinoma (ESCC) patients after concurrent chemoradiotherapy.SIRT1 and survivin proteins were immunohistochemically stained in 93 ESCC tissue specimens.SIRT1 was expressed in ESCC (80.6% vs 25.8% in normal mucosae) and survivin was expressed in 67.7% of ESCC vs 19.4% normal tissues (P < .01), and SIRT1 expression was associated with survivin expression (r = 0.39, P < .05). Furthermore, expression of both SIRT1 and survivin was associated with tumor size, depth of tumor invasion, tumor differentiation, lymph node metastasis, advanced clinical stage, and chemoradiotherapy (P < .05) as well as poor progression-free survival (PFS; P < .05) of ESCC patients after concurrent chemoradiotherapy (P < .05). Patient age, chemotherapy, tumor size, clinical stage, lymph node metastasis, and SIRT1 and survivin expression were independent PFS predictors (P < .05).Expression of both SIRT1 and survivin was associated with poor ESCC PFS.

Integrated Analysis of Hub Genes and Pathways In Esophageal Carcinoma Based on NCBI's Gene Expression Omnibus (GEO) Database: A Bioinformatics Analysis

BACKGROUND Esophageal carcinoma (ESCA) is a health challenge with poor prognosis and limited treatment options. Our aim is to screen for hub genes and pathways associated with ESCA pathology as diagnostic or therapeutic targets. MATERIAL AND METHODS We downloaded 2 ESCA-related datasets from the Gene Expression Omnibus (GEO) database. Subsequently, differentially expressed genes (DEGs) of ESCA were determined by statistical analysis. Both Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs were performed using online analytic tools. Network analysis was employed to construct a protein-protein interaction (PPI) network and to filter hub genes. We evaluated the expression level and impact of hub genes on survival of ESCA patients using the OncoLoc webserver. RESULTS A total of 210 DEGs were identified. The GO analysis showed that the DEGs were enriched in cell division. The KEGG pathway analysis showed DEGs that were enriched in cell cycle regulation, known cancer pathways, the PI3K-Akt signaling pathway, and the cGMP-PKG signaling pathway. The top 10 hub genes were markedly upregulated in ESCA tissue compared with normal esophageal tissue. Moreover, the expression level of the hub genes was different at different pathological stages of ESCA. Further prognostic analysis identified that the top 10 hub genes were related to late survival of ESCA patients, while exhibiting few associations with early survival time. CONCLUSIONS The signaling pathways involving the DEGs probably represent the pathological mechanism underlying ESCA. The hub genes were associated with survival of ESCA patients, and as such have the potential to serve as diagnostic indicators and therapeutic targets.

Lysyl oxidase-like 2 promotes esophageal squamous cell carcinoma cell migration independent of catalytic activity

Lysyl oxidase-like 2 (LOXL2) is a member of the lysyl oxidase (LOX) family that contributes to tumor cell metastasis. Our previous data identified two splice variants of LOXL2 (i.e., LOXL2 Δ72 and Δ13) in esophageal squamous cell carcinoma (ESCC) cells that increased cell invasiveness and migration but had lower LOX activities than wild-type LOXL2 (LOXL2 WT). We generated a series of LOXL2 deletion mutants with different deleted biochemical domains and examined the relationship between the cell migration abilities and catalytic activities, as well as subcellular locations, of these deletion mutants compared with LOXL2 WT in ESCC cells to explore the mechanism of LOXL2-driven ESCC cell migration. Our results indicated that the deletion mutants of LOXL2 had impaired deamination enzymatic activity; LOXL2 ΔSRCR4, which lacks the fourth scavenger receptor cysteine-rich (SRCR) domain, had lower enzymatic activity; and LOXL2 Y689F had no catalytic activity compared with LOXL2 WT. However these two mutants stimulated greater cellular migration than LOXL2 WT. Furthermore, the degree of cell migration promoted by LOXL2 ΔLO (in which the LOX-like domain was deleted) was higher than that of LOXL2 WT, and LOXL2 ΔSRCR3, which does not have the third SRCR domain, had lower LOX activity and cellular migration ability than LOXL2 WT. These results suggested that LOXL2 promotes ESCC cell migration independent of catalytic activity.

IFI6 depletion inhibits esophageal squamous cell carcinoma progression through reactive oxygen species accumulation via mitochondrial dysfunction and endoplasmic reticulum stress

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is one of the most lethal forms of adult cancer with poor prognosis. Substantial evidence indicates that reactive oxygen species (ROS) are important modulators of aggressive cancer behavior. However, the mechanism by which ESCC cells integrate redox signals to modulate carcinoma progression remains elusive.

METHODS

The expression of interferon alpha inducible protein 6 (IFI6) in clinical ESCC tissues and cell lines was detected by RT-PCR and Western blotting. The correlation between IFI6 expression levels and aggressive ESCC disease stage was examined by immunohistochemistry. Bioinformatic analysis was conducted to explore the potential function of IFI6 in ESCC. ESCC cell lines stably depleted of IFI6 and ectopically expressing IFI6 were established using lentiviruses expressing shRNAs and an IFI6 expression plasmid, respectively. The effects of IFI6 on ESCC cells were determined by cell-based analyses, including EdU assay, apoptotic assay, cellular and mitochondria-specific ROS detection, seahorse extracellular flux, and mitochondrial calcium flux assays. Blue native-polyacrylamide gel electrophoresis was used to determine mitochondrial supercomplex assembly. Transcriptional activation of NADPH oxidase 4 (NOX4) via ATF3 was confirmed by dual luciferase assay. In vivo tumor growth was determined in mouse xenograft models.

RESULTS

We find that the expression of IFI6, an IFN-stimulated gene localized in the inner mitochondrial membrane, is markedly elevated in ESCC patients and a panel of ESCC cell lines. High IFI6 expression correlates with aggressive disease phenotype and poor prognosis in ESCC patients. IFI6 depletion suppresses proliferation and induces apoptosis by increasing ROS accumulation. Mechanistically, IFI6 ablation induces mitochondrial calcium overload by activating mitochondrial Ca2+ uniporter and subsequently ROS production. Following IFI6 ablation, mitochondrial ROS accumulation is also induced by mitochondrial supercomplex assembly suppression and oxidative phosphorylation dysfunction, while IFI6 overexpression produces the opposite effects. Furthermore, energy starvation induced by IFI6 inhibition drives endoplasmic reticulum stress through disrupting endoplasmic reticulum calcium uptake, which upregulates NOX4-derived ROS production in an ATF3-dependent manner. Finally, the results in xenograft models of ESCC further corroborate the in vitro findings.

CONCLUSION

Our study unveils a novel redox homeostasis signaling pathway that regulates ESCC pathobiology and identifies IFI6 as a potential druggable target in ESCC.

Widely targeted metabolomic analyses unveil the metabolic variations after stable knock-down of NME4 in esophageal squamous cell carcinoma cells

NME4, also designated nm23-H4 or NDPK-D, has been known for years for its well-established roles in the synthesis of nucleoside triphosphates, though; little has been known regarding the differential metabolites involved as well as the biological roles NME4 plays in proliferation and invasion of esophageal squamous cell carcinoma (ESCC) cells. To understand the biological roles of NME4 in ESCC cells, lentiviral-based short hairpin RNA interference (shRNA) vectors were constructed and used to stably knock down NME4. Then, the proliferative and invasive variations were assessed using MTT, Colony formation and Transwell assays. To understand the metabolites involved after silencing of NME4 in ESCC cells, widely targeted metabolomic screening was taken. It was discovered that silencing of NME4 can profoundly suppress the proliferation and invasion in ESCC cells in vitro. Metabolically, a total of 11 differential metabolites were screened. KEGG analyses revealed that Tryptophan, Riboflavin, Purine, Nicotinate, lysine degradation, and Linoleic acid metabolism were also involved in addition to the well-established nucleotides metabolism. Some of these differential metabolites, say, 2-Picolinic Acid, Nicotinic Acid and Pipecolinic Acid were suggested to be associated with tumor immunomodulation. The data we described here support the idea that metabolisms occurred in mitochondrial was closely related to tumor immunity.

Depletion of LAMP3 enhances PKA-mediated VASP phosphorylation to suppress invasion and metastasis in esophageal squamous cell carcinoma

Metastasis is still a major cause of cancer-related mortality. Lysosome-associated membrane protein 3 (LAMP3) has been implicated in the invasiveness and metastasis of multiple cancer types; however, the underlying mechanisms are unclear. In this study, we found that LAMP3 was overexpressed in esophageal squamous cell carcinoma (ESCC) tissues and that this increased expression positively correlated with lymph node metastasis. Depletion of LAMP3 dramatically suppressed the motility of ESCC cells in vitro and experimental pulmonary and lymph node metastasis in vivo. Importantly, knockdown of LAMP3 increased the level of phosphorylated VASP(Ser239), which attenuated the invasive and metastatic capability of ESCC cells. We identified that cAMP-dependent protein kinase A (PKA) was responsible for the phosphorylation of VASP at Ser239. Consistently, silencing of PKA regulatory subunits diminished Ser239 phosphorylation on VASP and restored the motility capacity of LAMP3-depleted ESCC cells. In conclusion, we uncovered a previously unknown role of LAMP3 in promoting cellular motility and metastasis in ESCC.

Crosstalk between MEIS1 and markers of different cell signaling pathways in esophageal squamous cell carcinoma

The homeobox transcription factor MEIS1 is involved in cell fate decision, stem cells properties, gastrointestinal (GI) tract development, and progression of several malignancies such as esophageal squamous cell carcinoma (ESCC). Increasing evidences suggest the crosstalk between MEIS1 and cell signaling pathways. Therefore, our aim in present study was to investigate the probable linkage of MEIS1 expression with key genes of different cell signaling pathways in ESCC tumorigenesis, and their correlation with clinicopathological feature of the patients. The gene expression profiling of MEIS1 and different cell signaling genes including SALL4, SIZN1, and HEY1 (stemness state, BMP, and NOTCH signaling pathways, respectively) was performed using quantitative real-time reverse transcription polymerase chain reaction (PCR) in fresh tumoral compared to margin normal tissues of 50 treatment-naive ESCC samples. The mRNA expression of MEIS1/SIZN1, SIZN1/HEY1, and SIZN1/SALL4 were significantly associated to each other (P < 0.05). There were remarkable correlations between concomitant mRNA expression of MEIS1 and SIZN1 in tumors with invasion to adventitia, early stages of tumor progression and poorly differentiated tumors. Moreover, expression of MEIS1 and HEY1 was correlated to each other in primary stages of tumor progression and non-invaded tumors. Expression of MEIS1 was significantly associated with SALL4 in poorly differentiated tumors. Our results indicated that correlation between different cell signaling pathway-related genes may lead to esophageal tumorigenesis. It is illustrated that MEIS1 as a HOX gene has a significant correlation with stemness state, BMP, and NOTCH signaling pathways via the SIZN1.

MicroRNA-301b and its target gene synaptosome-associated protein 91 as important modulators in esophageal cancer: functional experiments

The aim of this study was to probe the influence of microRNA-301b (miR-301b) in esophageal cancer pathogenesis. Based on the data acquired from The Cancer Genome Atlas database, we found that miR-301b was highly expressed in esophageal cancer tissues and high expression of miR-301b was related to worse prognosis in patients with esophageal cancer. Quantitative real-time PCR revealed that the expression of miR-301b was higher in all examined esophageal cancer cell lines (ECA109, KY-SE150, TE-1, and NEC) than that in a human esophageal epithelial cell line (HEEC). Upregulation/downregulation of miR-301b facilitated/suppressed the growth, migration, and invasion of ECA109/KY-SE150 cells. Synaptosome-associated protein 91 (SNAP91) was proved to be one of the target genes of miR-301b and was negatively modulated by miR-301b. Besides, SNAP91 was lowly expressed in human esophageal cancer tissues and cell lines. Meanwhile, low expression of SNAP91 was concerned with poor prognosis in patients with esophageal cancer. Furthermore, we discovered that overexpression/depletion of SNAP91 suppressed/facilitated the proliferation of KY-SE150/ECA109 cells. MiR-301b and SNAP91 had little impact on HEEC cell proliferation and this degree of influence was negligible compared with their impacts on esophageal cancer cell proliferation. By rescue assay, we showed that overexpression of SNAP91 restrained the growth, migration, and invasion of ECA109 cells with overexpressed miR-301b while knockdown of SNAP91 showed the contrary effects on KY-SE150 cells with downregulated miR-301b. These consequences indicated that miR-301b played an important effect on esophageal cancer cells through regulating SNAP91, insinuating that miR-301b/SNAP91 might be novel potential targets for esophageal cancer therapy and prognosis.

RUNX3 inhibits the invasion and migration of esophageal squamous cell carcinoma by reversing the epithelial‑mesenchymal transition through TGF‑β/Smad signaling

Runt‑related transcription factor 3 (RUNX3) is a candidate tumor suppressor, and its inactivation may play a crucial role in the carcinogenesis process of numerous cancer types, including esophageal squamous cell carcinoma (ESCC). We previously revealed that RUNX3 inactivation was correlated with lymph node metastasis (LNM) and ESCC recurrence. However, the exact mechanisms of this process are still under investigation. The aim of the present study was to examine the potential roles and underlying molecular mechanisms of RUNX3 in ESCC metastasis and the epithelial‑mesenchymal transition (EMT). According to the results, RUNX3 expression in ESCC tissue was significantly reduced compared with that in adjacent normal tissue (0.50±0.20 vs. 0.83±0.16; P<0.001). In addition, statistical analysis revealed a close association between decreased RUNX3 expression and T status (P=0.027) and LNM (P=0.017) in ESCC patients. Pearson's correlation coefficient analysis was then used to evaluate correlations between RUNX3 and EMT‑related marker expression. The results revealed that RUNX3 expression in ESCC tissues was negatively correlated with the expression of N‑cadherin (r=‑0.429; P<0.01) and Snail (r=‑0.364; P<0.01) and positively correlated with the expression of E‑cadherin (r=0.580; P<0.01). Moreover, Eca109 and EC9706 cell invasion, migration, MMP‑9 expression and EMT were significantly inhibited by RUNX3 overexpression. Notably, further analysis revealed that RUNX3 overexpression markedly inhibited the phosphorylation of Smad2/3; RUNX3‑overexpressing cells also displayed less sensitivity to TGF‑β1‑induced EMT than control cells. Thus, RUNX3 may inhibit the invasion and migration of ESCC cells by reversing EMT through TGF‑β/Smad signaling and may be useful as a therapeutic target.

piR-823 demonstrates tumor oncogenic activity in esophageal squamous cell carcinoma through DNA methylation induction via DNA methyltransferase 3B

Piwi-interacting RNAs (piRNAs) dysregulation occurs frequently in extensive cancers. However, there was no report about piRNA expression in esophageal cancer (EC). In this study, the expression levels of piR-823 and DNMT1, DNMT3A, DNMT3B were detected in 54 pairs of ESCC tissues and adjacent normal tissues using the quantitative real-time polymerase chain reaction method. Pearson's chi-squared test and receiver operating characteristic curves were established to evaluate the diagnostic and prognostic value of piR-823 in ESCC. Spearman's correlation analysis was used to evaluate the association between piR-823 and DNMTs. We found that piR-823 was significantly upregulated in ESCC tissues compared with matched normal tissues (P = 0.0213), the level of piR-823 was significantly associated with lymph node metastasis (P = 0.042). The ROC curve analysis of piR-823 expression level yielded an area under the ROC curve value of 0.713 (P = 0.0001). DNMT3B was upregulated in ESCC tissues compared with matched normal tissues (P = 0.0286). There was an obvious positive correlation between piR-823 and DNMT3B expression (r = 0.6420, P < 0.0001). In conclusion, for the first time, we provided evidence about piRNA expression in EC. piRNA-823 and DNMT3B were both upregulated in ESCC and positively correlated with each other, suggesting the tumor oncogenic role of piR-823 in ESCC to epigenetically induce aberrant DNA methylation through DNMT3B. In addition, piRNA-823 showed high specificity in detecting ESCC and higher piRNA-823 level indicated higher risk of lymph node metastasis, suggesting its diagnostic and prognostic biomarker potential.

Splice variant of growth hormone-releasing hormone receptor drives esophageal squamous cell carcinoma conferring a therapeutic target

The extrahypothalamic growth hormone-releasing hormone (GHRH) and its cognate receptors (GHRH-Rs) and splice variants are expressed in a variety of cancers. It has been shown that the pituitary type of GHRH-R (pGHRH-R) mediates the inhibition of tumor growth induced by GHRH-R antagonists. However, GHRH-R antagonists can also suppress some cancers that do not express pGHRH-R, yet the underlying mechanisms have not been determined. Here, using human esophageal squamous cell carcinoma (ESCC) as a model, we were able to reveal that SV1, a known splice variant of GHRH-R, is responsible for the inhibition induced by GHRH-R antagonist MIA-602. We demonstrated that GHRH-R splice variant 1 (SV1) is a hypoxia-driven promoter of tumor progression. Hypoxia-elevated SV1 activates a key glycolytic enzyme, muscle-type phosphofructokinase (PFKM), through the nuclear factor kappa B (NF-κB) pathway, which enhances glycolytic metabolism and promotes progression of ESCC. The malignant actions induced by the SV1-NF-κB-PFKM pathway could be reversed by MIA-602. Altogether, our studies demonstrate a mechanism by which GHRH-R antagonists target SV1. Our findings suggest that SV1 is a hypoxia-induced oncogenic promoter which can be an alternative target of GHRH-R antagonists.

NME4 modulates PD-L1 expression via the STAT3 signaling pathway in squamous cell carcinoma

NME4, also named Nm23-H4, is a contraction of NME/NM23 Nucleoside Diphosphate Kinase 4, whose major role is the synthesis of nucleoside triphosphates. However, its association with programmed death ligand 1 (PD-L1) remains far from understood. Herein, it was discovered that silencing NME4 can lead to the marked downregulation of PD-L1, with phosphorylated STAT3 at the 705th serine being inactivated in vitro in esophageal squamous cell carcinoma (ESCC) cell lines. To further validate the association between NME4 and PD-L1 that was observed in cell lines, Pearson correlation analysis was performed on the data regarding the transcriptomic RNA sequencing of NME4 and PD-L1 in cervical squamous cell carcinoma (CSCC), which pathologically highly resembles ESCC in terms of tumor origin, obtained from the GEPIA database. It was demonstrated that their correlation was significant but negative between NME4 and PD-L1 in CSCC. To the best of our knowledge, this is the first report describing a modulation exerted by NME4 over PD-L1 in the background of squamous cell carcinoma, strongly suggestive of the underlying role of NME4 working to exclude CD8 T cells from infiltrating into the squamous cell carcinoma microenvironment.

The role of substance P/neurokinin 1 receptor in the pathogenesis of esophageal squamous cell carcinoma through constitutively active PI3K/Akt/NF-κB signal transduction pathways

One of the most prevalent malignancies is esophageal squamous cell carcinoma (ESCC), which is associated with high morbidity and mortality. Substance P (SP), as one of the peptides released from sensory nerves, causes the enhancement of cellular excitability through the activation of the neurokinin-1 (NK1) receptor in several human tumor cells. Aprepitant, a specific, potent, and long-acting NK1 receptor antagonist, is considered as a novel agent to inhibit proliferation and induce apoptosis in malignant cells. Since the antitumor mechanism of aprepitant in ESCC is not completely understood, we conducted this study and found that aprepitant induced growth inhibition of KYSE-30 cells and arrested cells in the G2/M phase of the cell cycle. Aprepitant also caused apoptotic cell death and inhibited activation of the PI3K/Akt axis and its downstream effectors, including NF-κB in KYSE-30 cells. Besides, quantitative real-time (qRT)-PCR analysis showed a significant down-regulation of NF-κB target genes in KYSE-30 cells, indicating a probable NF-κB-dependent mechanism involved in aprepitant cytotoxicity. Thus, the present study recommends that SP/NK1R system might, therefore, be considered as an emerging and promising therapeutic strategy against ESCC.

Prognostic role of secreted protein acidic and rich in cysteine in patients with solid tumors

OBJECTIVES

To analyze the heterogeneous functions of secreted protein acidic and rich in cysteine (SPARC) from different origins and in different tumor microenvironments with the purpose of determining its clinical significance. Methods: The PubMed, CINAHL, Cochrane, Web of Science and Embase databases were utilized. Studies that focused on the effects of SPARC expression on solid tumor progression and clinical implications were used. The different outcomes including overall survival and disease-free survival were analyzed to evaluate their relations with tumor- and stroma-derived SPARC expression. Results: A total of 26 studies including 5,939 patients were enrolled in the present meta-analysis. Tumor-derived SPARC overexpression was significantly related with poor overall survival (hazard ratio: 1.478; 95% CI: 1.143-1.910; p=0.003), and a similar tendency was also observed in disease-free survival (hazard ratio: 1.476; 95% CI: 0.993-2.195; p=0.054). However, the hazard ratios for overall survival and disease-free survival did not present a statistical trend in stromal SPARC overexpression. Tumor type subgroup analysis revealed marked heterogeneity among outcomes. In pancreatic cancer, SPARC overexpression in the stroma was significantly associated with poorer overall survival and disease-free survival. In colorectal cancer, SPARC overexpression in the stroma was associated with better disease-free survival. Conclusion: For the majority of solid tumors, SPARC in cancer cells may be an unfavorable indicator for long-term survival for patients. As for stromal expression, SPARC indicates a poorer prognosis in pancreatic cancer, but a better disease-free survival in colorectal cancer. Secreted protein acidic and rich in cysteine might be a potential biomarker for solid tumor prognosis.

Identification of key genes by integrating DNA methylation and next-generation transcriptome sequencing for esophageal squamous cell carcinoma

Aberrant DNA methylation leads to abnormal gene expression, making it a significant regulator in the progression of cancer and leading to the requirement for integration of gene expression with DNA methylation. Here, we identified 120 genes demonstrating an inverse correlation between DNA methylation and mRNA expression in esophageal squamous cell carcinoma (ESCC). Sixteen key genes, such as SIX4, CRABP2, and EHD3, were obtained by filtering 10 datasets and verified in paired ESCC samples by qRT-PCR. 5-Aza-dC as a DNA methyltransferase (DNMT) inhibitor could recover their expression and inhibit clonal growth of cancer cells in seven ESCC cell lines. Furthermore, 11 of the 16 genes were correlated with OS (overall survival) and DFS (disease-free survival) in 125 ESCC patients. ChIP-Seq data and WGBS data showed that DNA methylation and H3K27ac histone modification of these key genes displayed inverse trends, suggesting that there was collaboration between DNA methylation and histone modification in ESCC. Our findings illustrate that the integrated multi-omics data (transcriptome and epigenomics) can accurately obtain potential prognostic biomarkers, which may provide important insight for the effective treatment of cancers.

Four transcription profile-based models identify novel prognostic signatures in oesophageal cancer

Oesophageal cancer (ESCA) is a clinically challenging disease with poor prognosis and health-related quality of life. Here, we investigated the transcriptome of ESCA to identify high risk-related signatures. A total of 159 ESCA patients of The Cancer Genome Atlas (TCGA) were sorted by three phases. In the discovery phase, differentially expressed transcripts were filtered; in the training phase, two adjusted Cox regressions and two machine leaning models were used to construct and estimate signatures; and in the validation phase, prognostic signatures were validated in the testing dataset and the independent external cohort. We constructed two signatures from three types of RNA markers by Akaike information criterion (AIC) and least absolute shrinkage and selection operator (LASSO) Cox regressions, respectively, and all candidate markers were further estimated by Random Forest (RFS) and Support Vector Machine (SVM) algorithms. Both signatures had good predictive performances in the independent external oesophageal squamous cell carcinoma (ESCC) cohort and performed better than common clinicopathological indicators in the TCGA dataset. Machine learning algorithms predicted prognosis with high specificities and measured the importance of markers to verify the risk weightings. Furthermore, the cell function and immunohistochemical (IHC) staining assays identified that the common risky marker FABP3 is a novel oncogene in ESCA.