Potential Therapeutic Target For Esophageal Squamous Cell Carcinoma Research Articles

Ferroptosis suppressor genes are highly expressed in esophageal cancer to inhibit tumor cell ferroptosis

To explore the role of ferroptosis-related genes in regulating ferroptosis of esophageal squamous cell carcinoma (ESCC). ESCC datasets GSE161533 and GSE20347 were downloaded from the Gene Expression Omnibus (GEO) to identify the differentially expressed genes (DEGs) using R software. ESCC ferroptosis-related genes obtained by intersecting the DEGs with ferroptosis-related genes from FerrDb were analyzed using GO and KEGG analyses, protein-protein interaction (PPI) network analysis, and core gene identification through Cytoscape. The identified ferroptosis suppressor genes were validated using TCGA database, and their expression levels were detected using RT-qPCR in cultured normal esophageal cells and ESCC cells. Six ferroptosis suppressor genes (RRM2, GCLC, TFRC, TXN, SLC7A11, and EZH2) were downregulated with siRNA in ESCC cells, and the changes in cell proliferation and apoptosis were assessed with CCK8 assay and flow cytometry; Western blotting was performed to examine the changes in ferroptosis progression of the cells. We identified a total of 58 ESCC ferroptosis-related genes, which involved such biological processes as glutathione transmembrane transport, iron ion transport, and apoptosis and the ferroptosis, glutathione metabolism, and antifolate resistance pathways. The PPI network included 54 nodes and 74 edges with a clustering coefficient of 0.522 and PPI enrichment P<0.001. Cytoscape identified 6 core ferroptosis suppressor genes (RRM2, TFRC, TXN, EZH2, SLC7A11, and GCLC), which were highly expressed in ESCC tissues in the TCGA dataset and in ESCC cell lines. Downregulating these genes in ESCC TE1 cells significantly inhibited cell proliferation, promoted cell apoptosis, reduced the expression levels of ferroptosis markers GPX4 and FIH1, and increased the expression of ACSL4. High expression of ferroptosis suppressor genes in ESCC may cause arrest of ferroptosis progression to facilitate tumor development, and inhibiting these genes can restore ferroptosis and promote cell apoptosis, suggesting their value as potential therapeutic targets for ESCC.

CircRNA6448-14/miR-455-3p/OTUB2 axis stimulates glycolysis and stemness of esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is a gastrointestinal malignancy with high incidence. This study aimed to reveal the complete circRNA-miRNA-mRNA regulatory network in ESCC and validate its function mechanism. Expression of OTU Domain-Containing Ubiquitin Aldehyde-Binding Protein 2 (OTUB2) in ESCC was analyzed by bioinformatics to find the binding sites between circRNA6448-14 and miR-455-3p, as well as miR-455-3p and OTUB2. The binding relationships were verified by RNA Immunoprecipitation (RIP) and dual-luciferase assay. The expressions of circRNA6448-14, miR-455-3p, and OTUB2 were detected by quantitative real-time polymerase chain reaction (qRT-PCR). MTT assay measured cell viability, and the spheroid formation assay assessed the ability of stem cell sphere formation. Western blot (WB) determined the expression of marker proteins of stem cell surface and rate-limiting enzyme of glycolysis. The Seahorse XFe96 extracellular flux analyzer measured the rate of extracellular acidification rate and cellular oxygen consumption. Corresponding assay kits assessed cellular glucose consumption, lactate production, and adenosine triphosphate (ATP) generation. In ESCC, circRNA6448-14 and OTUB2 were highly expressed in contrast to miR-455-3p. Knocking down circRNA6448-14 could prevent the glycolysis and stemness of ESCC cells. Additionally, circRNA6448-14 enhanced the expression of OTUB2 by sponging miR-455-3p. Overexpression of OTUB2 or silencing miR-455-3p reversed the inhibitory effect of knockdown of circRNA6448-14 on ESCC glycolysis and stemness. This research demonstrated that the circRNA6448-14/miR-455-3p/OTUB2 axis induced the glycolysis and stemness of ESCC cells. Our study revealed a novel function of circRNA6448-14, which may serve as a potential therapeutic target for ESCC.

Annexin A2 combined with TTK accelerates esophageal cancer progression via the Akt/mTOR signaling pathway

Annexin A2 (ANXA2) is a widely reported oncogene. However, the mechanism of ANXA2 in esophageal cancer is not fully understood. In this study, we provided evidence that ANXA2 promotes the progression of esophageal squamous cell carcinoma (ESCC) through the downstream target threonine tyrosine kinase (TTK). These results are consistent with the up-regulation of ANXA2 and TTK in ESCC. In vitro experiments by knockdown and overexpression of ANXA2 revealed that ANXA2 promotes the progression of ESCC by enhancing cancer cell proliferation, migration, and invasion. Subsequently, animal models also confirmed the role of ANXA2 in promoting the proliferation and metastasis of ESCC. Mechanistically, the ANXA2/TTK complex activates the Akt/mTOR signaling pathway and accelerates epithelial-mesenchymal transition (EMT), thereby promoting the invasion and metastasis of ESCC. Furthermore, we identified that TTK overexpression can reverse the inhibition of ESCC invasion after ANXA2 knockdown. Overall, these data indicate that the combination of ANXA2 and TTK regulates the activation of the Akt/mTOR pathway and accelerates the progression of ESCC. Therefore, the ANXA2/TTK/Akt/mTOR axis is a potential therapeutic target for ESCC.

Circular RNA circCHSY1 silencing inhibits the malignant progression of esophageal squamous cell carcinoma

BackgroundCircRNAs play a crucial role in the regulation of various cancers. This study aims to investigate the involvement of circCHSY1 in the development of esophageal squamous cell carcinoma (ESCC).MethodsRNA levels were quantified using qRT-PCR, and protein levels were measured by western blot. The stability of circCHSY1 was analyzed using RNase R. The functional effect of circCHSY1 on cell behavior was evaluated by CCK-8, EdU, flow cytometry, transwell, tube formation, and xenograft tumor model assays. The associations among circCHSY1, miR-1229-3p, and Tectonic-1 (TCTN1) were certified by bioinformatics analysis, dual-luciferase reporter assay, and RNA pull-down assay.ResultsCircCHSY1 was up-regulated in both ESCC tissues and cell lines in comparison with the control groups. Knockdown of circCHSY1 inhibited the proliferation, migration, invasion, and tube formation and promoted apoptosis of ESCC cells. Mechanistically, circCHSY1 targeted miR-1229-3p, which was downregulated in ESCC tissues and cells. Inhibition of miR-1229-3p attenuated the effects mediated by circCHSY1 suppression. Besides, miR-1229-3p bound to TCTN1, and TCTN1 overexpression restored miR-1229-3p-induced effects in ESCC cells. Animal experiments revealed that circCHSY1 silencing suppressed tumor tumorigenesis in vivo.ConclusionCircCHSY1 contributed to ESCC cell malignancy, and the underlying mechanism involved the circCHSY1/miR-1229-3p/TCTN1 axis, providing potential therapeutic targets for ESCC.

Role of deubiquitinase JOSD2 in the pathogenesis of esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is a deadly malignancy with limited treatment options. Deubiquitinases (DUBs) have been confirmed to play a crucial role in the development of malignant tumors. JOSD2 is a DUB involved in controlling protein deubiquitination and influencing critical cellular processes in cancer. To investigate the impact of JOSD2 on the progression of ESCC. Bioinformatic analyses were employed to explore the expression, prognosis, and enriched pathways associated with JOSD2 in ESCC. Lentiviral transduction was utilized to manipulate JOSD2 expression in ESCC cell lines (KYSE30 and KYSE150). Functional assays, including cell proliferation, colony formation, drug sensitivity, migration, and invasion, were performed, revealing the impact of JOSD2 on ESCC cell lines. JOSD2's role in xenograft tumor growth and drug sensitivity in vivo was also assessed. The proteins that interacted with JOSD2 were identified using mass spectrometry. Preliminary research indicated that JOSD2 was highly expressed in ESCC tissues, which was associated with poor prognosis. Further analysis demonstrated that JOSD2 was upregulated in ESCC cell lines compared to normal esophageal cells. JOSD2 knockdown inhibited ESCC cell activity, including proliferation and colony-forming ability. Moreover, JOSD2 knockdown decreased the drug resistance and migration of ESCC cells, while JOSD2 overexpression enhanced these phenotypes. In vivo xenograft assays further confirmed that JOSD2 promoted tumor proliferation and drug resistance in ESCC. Mechanistically, JOSD2 appears to activate the MAPK/ERK and PI3K/AKT signaling pathways. Mass spectrometry was used to identify crucial substrate proteins that interact with JOSD2, which identified the four primary proteins that bind to JOSD2, namely USP47, IGKV2D-29, HSP90AB1, and PRMT5. JOSD2 plays a crucial role in enhancing the proliferation, migration, and drug resistance of ESCC, suggesting that JOSD2 is a potential therapeutic target in ESCC.

Phospholipase PLCE1 Promotes Transcription and Phosphorylation of MCM7 to Drive Tumor Progression in Esophageal Cancer.

PLCE1 promotes tumor progression in ESCC by activating PKCα-mediated phosphorylation of E2F1 to upregulate MCM7 and miR-106b-5p expression and by potentiating MCM7 phosphorylation by RIOK2.

USP4 promotes the proliferation, migration, and invasion of esophageal squamous cell carcinoma by targeting TAK1

Ubiquitin-specific protease 4 (USP4) represents a potential oncogene involved in various human cancers. Nevertheless, the biological roles and precise mechanism of USP4 in esophageal squamous cell carcinoma (ESCC) progression are not understood. Here, USP4 expression was found to be markedly upregulated in ESCC tumor tissues and cells. Loss- and gain-of-function assays suggested that USP4 silencing inhibited ESCC cell proliferation, migration, and invasion, while USP4 overexpression promoted these behaviors. Consistently, USP4 silencing repressed tumor growth and metastasis in an ESCC nude mouse model in vivo. As a target molecule of USP4, transforming growth factor-β-activated kinase 1 (TAK1) also showed high expression in ESCC. Moreover, we observed that USP4 specifically interacted with TAK1 and stabilized TAK1 protein levels via deubiquitination in ESCC cells. Importantly, USP4 promotes ESCC proliferation, migration, and invasion via the MEK/ERK signaling pathway and can be inhibited by U0126. Neutral red (NR), an inhibitor of USP4 can suppress ESCC progression in vitro and in vivo. Overall, this study revealed that USP4/TAK1 plays crucial roles in ESCC progression by modulating proliferation, migration, and invasion, and USP4 might be a potential therapeutic target in ESCC.

Ezrin promotes esophageal squamous cell carcinoma progression via the Hippo signaling pathway.

The aim of this study was to analyze the role of Ezrin in esophageal squamous cell carcinoma (ESCC) and investigate potential therapeutic targets for ESCC by interfering with Ezrin expression. Bioinformatics analysis revealed that Ezrin expression differed significantly among patients with different clinical stage ESCC. Moreover, there was a significant correlation between Ezrin and yes-associated protein/connective tissue growth factor (YAP1/CTGF) levels in esophageal cancer. Sixty paraffin-embedded ESCC tissue samples were examined and Ezrin and YAP1/CTGF levels were determined using immunohistochemistry. The positive expression rates of Ezrin and YAP1/CTGF were significantly lower in adjacent tissues than in ESCC tissues. Furthermore, knockdown of Ezrin expression inhibited colony formation and reduced cell migration and invasion. Compared with control ESCC cells, protein expression levels of YAP1 and CTGF were significantly downregulated in cells with Ezrin knocked down. We conclude that Ezrin may be involved in ESCC progression through the Hippo signaling pathway.

Role of exosome-mediated molecules SNORD91A and SLC40A1 in M2 macrophage polarization and prognosis of ESCC

BackgroundExosome-mediated interaction serves as a significant regulatory factor for M2 macrophage polarization in cancer.MethodsAll accessible data were acquired from The Cancer Genome Atlas (TCGA) database and analyzed using R software. Molecules implicated in exocrine secretion were amassed from the ExoCarta database. Our research initially quantified the immune microenvironment in Esophageal Squamous Cell Carcinoma (ESCC) patients based on the expression profile sourced from the TCGA database. Additionally, we delved into the biological role of M2 macrophages in ESCC via Gene Set Enrichment Analysis (GSEA).ResultsWe observed that patients with high M2 macrophage infiltration typically have a poorer prognosis. Subsequently, a total of 1457 molecules were identified, with 103 of these molecules believed to function through exocrine mechanisms, as supported by data from the ExoCarta database. SNORD91A and SLC40A1 were ultimately pinpointed due to their correlation with patient prognosis. Moreover, we investigated their potential roles in ESCC, including biological enrichment, immune infiltration, and genomic instability analysis.ConclusionsOur study identified exosome-associated molecules, namely SNORD91A and SLC40A1, which notably impact ESCC prognosis and local M2 macrophage recruitment, thereby presenting potential therapeutic targets for ESCC.

CircRNA PDE3B regulates tumorigenicity via the miR-136-5p/MAP3K2 axis of esophageal squamous cell carcinoma.

CircRNA has a covalently closed circular conformation and a stable structure. However, the exact role of circRNA in esophageal squamous cell carcinoma (ESCC) remains uncertain. The purpose of this study was to explore the role of hsa_circ_0000277 (circ_PDE3B) in ESCC. The expression levels of circ_PDE3B, miR-136-5p and mitogen-activated protein kinase kinase kinase 2 (MAP3K2) in ESCC tissues and cells were detected by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot. The proliferation ability of EC9706 and KYSE30 cells was detected by clonal formation, 5-ethynyl-2'-deoxyuridine (EdU) and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assays. Flow cytometry was used to detect the apoptosis rate of cells. Transwell assay was used to detect the invasion ability of EC9706 and KYSE3 cells. The relationship between miR-136-5p and circ_PDE3B or MAP3K2 was verified by dual-luciferase reporter assay and RNA pull-down, and the effect of circ_PDE3B on tumor growth in vivo was explored through tumor transplantation experiment. Immunohistochemistry (IHC) assay was used to detect MAP3K2 and Ki67 expression in mice tumor tissues. The results showed that circ_PDE3B was highly expressed in ESCC tissues and cells. Downregulated circ_PDE3B expression in ESCC cells significantly reduced cell proliferation, migration and invasion. Circ_PDE3B served as a sponge for miR-136-5p, and miR-136-5p inhibition reversed the roles of circ_PDE3B knockdown in ESCC cells. MAP3K2 was a direct target of miR-136-5p, and miR-136-5p targeted MAP3K2 to inhibit the malignant behaviors of ESCC cells. Furthermore, circ_PDE3B regulated MAP3K2 expression by sponging miR-136-5p. Importantly, circ_PDE3B knockdown inhibited tumor growth in vivo. In conclusion, circ_PDE3B acted as oncogenic circRNA in ESCC and accelerated ESCC progression by adsorption of miR-136-5p and activation of MAP3K2, supporting circ_PDE3B as a potential therapeutic target for ESCC.

Circular RNA circ-FIRRE interacts with HNRNPC to promote esophageal squamous cell carcinoma progression by stabilizing GLI2 mRNA.

Increasing evidence has shown that circular RNAs (circRNAs) interact with RNA-binding proteins (RBPs) and promote cancer progression. However, the function and mechanism of the circRNA/RBP complex in esophageal squamous cell carcinoma (ESCC) are still largely unknown. Herein, we first characterized a novel oncogenic circRNA, circ-FIRRE, by RNA sequencing (Ribo-free) profiling of ESCC samples. Furthermore, we observed marked circ-FIRRE overexpression in ESCC patients with high TNM stage and poor overall survival. Mechanistic studies indicated that circ-FIRRE, as a platform, interacts with the heterogeneous nuclear ribonucleoprotein C (HNRNPC) protein to stabilize GLI2 mRNA by directly binding to its 3'-UTR in the cytoplasm, thereby resulting in elevated GLI2 protein expression and subsequent transcription of its target genes MYC, CCNE1, and CCNE2, ultimately contributing to ESCC progression. Moreover, HNRNPC overexpression in circ-FIRRE knockdown cells notably abolished circ-FIRRE knockdown-mediated Hedgehog pathway inhibition and ESCC progression impairment in vitro and in vivo. Clinical specimen results showed that circ-FIRRE and HNRNPC expression was positively correlated with GLI2 expression, which reveals the clear significance of the circ-FIRRE/HNRNPC-GLI2 axis in ESCC. In summary, our results indicate that circ-FIRRE could serve as a valuable biomarker and potential therapeutic target for ESCC and highlight a novel mechanism of the circ-FIRRE/HNRNPC complex in ESCC progression regulation.

Molecular Characterization of Esophageal Squamous Cell Carcinoma Using Quantitative Proteomics

Esophageal squamous cell carcinoma (ESCC) is a heterogeneous cancer associated with a poor prognosis in advanced stages. In India, it is the sixth most common cause of cancer-related mortality. In this study, we employed high-resolution mass spectrometry-based quantitative proteomics to characterize the differential protein expression pattern associated with ESCC. We identified several differentially expressed proteins including PDPN, TOP2A, POSTN and MMP2 that were overexpressed in ESCC. In addition, we identified downregulation of esophagus tissue-enriched proteins such as SLURP1, PADI1, CSTA, small proline-rich proteins such as SPRR3, SPRR2A, SPRR1A, KRT4, and KRT13, involved in squamous cell differentiation. We identified several overexpressed proteins mapped to the 3q24-29 chromosomal region, aligning with CNV alterations in this region reported in several published studies. Among these, we identified overexpression of SOX2, TP63, IGF2BP2 and RNF13 that are encoded by genes in the 3q26 region. Functional enrichment analysis revealed proteins involved in cell cycle pathways, DNA replication, spliceosome, and DNA repair pathways. We identified the overexpression of multiple proteins that play a major role in alleviating ER stress, including SYVN1 and SEL1L. The SYVN1/SEL1L complex is an essential part of the ER quality control machinery clearing misfolded proteins from the ER. SYVN1 is an E3 ubiquitin ligase that ubiquitinates ER-resident proteins. Interestingly, there are also other non-canonical substrates of SYVN1 which are known to play a crucial role in tumor progression. Thus, SYVN1 could be a potential therapeutic target in ESCC.

EXOC3L1: A Novel Prognostic Biomarker Correlated with Immune Infiltration in Esophageal Squamous Cell Carcinoma.

BACKGROUND Exocyst complex component 3-like 1 (EXOC3L1) is ubiquitously present in multiple organs. However, its role in esophageal squamous cell carcinoma (ESCC) remains unknown. The aim of this study was to explore the relationship between EXOC3L1 and ESCC. MATERIAL AND METHODS A total of 652 normal samples and 82 ESCC samples obtained from the University of California Santa Cruz (UCSC) Xena were applied to detect the expression difference of EXOC3L1. GSE53625 with 179 paired samples and GSE161533 with 28 paired samples were used for validation. The correlation between clinicopathological features and EXOC3L1 expression was calculated. Kaplan-Meier method was employed to assess the prognostic value of EXOC3L1 in ESCC. Univariate and multivariate Cox regression analyses were carried out to screen the factors contributing to the prognosis of ESCC. In addition, functional enrichment analysis, protein-protein interaction (PPI) network analysis, and immune infiltration analysis were conducted to identify the significantly involved functions of EXOC3L1. RESULTS EXOC3L1 was significantly overexpressed in ESCC compared to normal samples. High expression of EXOC3L1 was associated with worse prognosis, and univariate and multivariate Cox regression analysis demonstrated that EXOC3L1 was an independent prognostic predictor of ESCC. Functional enrichment analysis and immune infiltration analysis disclosed that the expression of EXOC3L1 was correlated with the abundance of several types of immune cells. CONCLUSIONS EXOC3L1 plays a crucial role in the prognosis of ESCC, and it may serve as a reliable biomarker for predicting the survival and a potential therapeutic target for ESCC.

LHX2 Enhances the Malignant Phenotype of Esophageal Squamous Cell Carcinoma by Upregulating the Expression of SERPINE2.

LHX2 dysregulations have been found to present in cancers, but the function of LHX2 in esophageal squamous cell carcinoma (ESCC) remains unknown. Here, we report that LHX2 was upregulated in ESCC tissues in comparison to the LHX2 levels in adjacent normal tissues. Loss- and gain-of-function experiments demonstrated that the knockdown of LHX2 markedly inhibited ESCC cells’ proliferation, migration, invasion, tumor growth and metastasis, whereas the overexpression of LHX2 had the opposite effects. A mechanistic investigation revealed that LHX2 bound to the promoter of SERPINE2 gene and transcriptionally regulated the expression of SERPINE2. Collectively, LHX2 facilitates ESCC tumor progression, and it could be a potential therapeutic target for ESCC.

MELK predicts poor prognosis and promotes metastasis in esophageal squamous cell carcinoma via activating the NF‑κB pathway.

Esophageal squamous cell carcinoma (ESCC) is one of the most common malignancies worldwide with a low 5-year survival rate due to the lack of effective therapeutic strategies. Accumulating evidence has indicated that maternal embryonic leucine zipper kinase (MELK) is highly expressed in several tumors and associated with tumor development. However, the biological effects of MELK in ESCC remain unknown. In the present study, cell phenotypical experiments and animal metastasis assays were performed to detect the influence of MELK knockdown in vitro and in vivo. The potential molecular mechanism of MELK-mediated ESCC metastasis was further investigated by western blotting and immunofluorescence staining. The results revealed that the expression of MELK in human ESCC tissues was higher than that in adjacent normal tissues and was positively associated with the poor prognosis of patients. Reducing MELK expression resulted in growth inhibition and suppression of the invasive ability of ESCC cells in vitro and in vivo. MELK inhibition induced alterations of epithelial-mesenchymal transition-associated proteins. Mechanistically, MELK interacted with IκB kinase (IKK) and promoted the phosphorylation of IKK, by which MELK regulated activation of the NF-κB pathway. Collectively, the present study revealed the function and mechanism of MELK in the cell metastasis of ESCC, which may be a potential therapeutic target for ESCC.

Targeting the SOX2/PARP1 complex to intervene in the growth of esophageal squamous cell carcinoma

Elevated SOX2 protein levels are closely correlated with the increased incidence of esophageal squamous cell carcinoma (ESCC). However, establishing effective target measures for ESCC treatments continue to be researched. It has been previously proposed that SOX2 represents a potential therapeutic target for ESCC. Here, we found that the enzyme Poly(ADP-Ribose) polymerase 1 (PARP1) enriched in ESCCs interact with SOX2. Inhibition of PARP1 with 3-aminobenzamide (3-ABA) or shRNA knockdown reduced the proliferation of ESCCs, accompanied by decreased protein levels of SOX2. RNA sequencing demonstrated that PARP1 inhibition affected multiple signaling pathways involved in cancer cell proliferation. Additionally, 3-ABA synergistically suppressed the growth of ESCC cells when combined with cisplatin, and metformin potentiated the suppressive effect of 3-ABA on ESCC cell growth. Together these findings suggest that targeting SOX2 binding partner PARP1 provides a possible avenue to treat patients with high levels of SOX2.

The Deubiquitinase USP39 Promotes Esophageal Squamous Cell Carcinoma Malignancy as a Splicing Factor.

Esophageal squamous cell carcinoma (ESCC) is an aggressive epithelial malignancy and the underlying molecular mechanisms remain elusive. Here, we identify that the ubiquitin-specific protease 39 (USP39) drives cell growth and chemoresistance by functional screening in ESCC, and that high expression of USP39 correlates with shorter overall survival and progression-free survival. Mechanistically, we provide evidence for the role of USP39 in alternative splicing regulation. USP39 interacts with several spliceosome components. Integrated analysis of RNA-seq and RIP-seq reveals that USP39 regulates the alternative splicing events. Taken together, our results indicate that USP39 functions as an oncogenic splicing factor and acts as a potential therapeutic target for ESCC.

ESCCAL-1 promotes cell-cycle progression by interacting with and stabilizing galectin-1 in esophageal squamous cell carcinoma

Long non-coding RNAs (LncRNAs) play important roles in the development of human esophageal squamous cell carcinoma (ESCC). Our previous studies have shown that knockdown of LncRNA ESCCAL-1 expression inhibits the growth of ESCC cells, but the mechanisms remain largely unknown. In this study, we show that over-expression of ESCCAL-1 promotes ESCC cell proliferation and cell-cycle progression by blocking ubiquitin-mediated degradation of an oncoprotein galectin-1 (Gal-1). Multiple LncRNA expression datasets as well as our own data together reveal that ESCCAL-1 is evidently up-regulated in ESCC tissues and exhibits promising diagnostic value. Over-expression of ESCCAL-1 augmented ESCC cell proliferation and cell-cycle progression, whereas down-regulation of ESCCAL-1 resulted in the opposite effects. Mechanistically, LncRNA ESCCAL-1 directly binds to Gal-1 and positively regulates its protein level without affecting its mRNA level. Up-regulation of Gal-1 facilitated ESCC cell proliferation and cell-cycle progress. Knockdown of Gal-1 mitigated the effects of ESCCAL-1-mediated high cellular proliferation, NF-κB signaling activation and tumorigenicity of ESCC cells. Thus, our findings provide novel insight into the mechanism by which ESCCAL-1 facilitates ESCC tumorigenesis and cell-cycle progression by interacting with and stabilizing Gal-1 protein, suggesting a potential therapeutic target for ESCC.

PTK7, a Catalytically Inactive Receptor Tyrosine Kinase, Increases Oncogenic Phenotypes in Xenograft Tumors of Esophageal Squamous Cell Carcinoma KYSE-30 Cells.

Protein tyrosine kinase 7 (PTK7), a catalytically defective receptor protein tyrosine kinase, is upregulated in tumor tissues and cell lines of esophageal squamous cell carcinoma (ESCC). We showed that PTK7 plays an oncogenic role in various ESCC cell lines. However, its role as an oncogene has not been demonstrated in vivo. Here, we examined the influence of PTK7 on the tumorigenic potential of ESCC KYSE-30 cells, which are known to establish xenograft tumors. Overexpression of PTK7 enhanced the proliferation, adhesion, wound healing, and migration of KYSE-30 cells, and these effects were reversed by the knockdown of PTK7. PTK7 overexpression and knockdown, respectively, increased and decreased the tyrosine phosphorylation of cellular proteins and the phosphorylation of ERK, AKT, and FAK, which are important for cell proliferation, survival, adhesion, and migration. Additionally, PTK7 overexpression and silencing, respectively, increased and decreased the weight, volume, and number of Ki-67-positive proliferating cells in xenograft tumors of KYSE-30 cells. Therefore, we propose that PTK7 plays an important role in the tumorigenesis of ESCC cells in vivo and is a potential therapeutic target for ESCC.

CircRNA-DOPEY2 enhances the chemosensitivity of esophageal cancer cells by inhibiting CPEB4-mediated Mcl-1 translation

BackgroundCisplatin-based chemotherapy is a mainstay systematic therapy for advanced esophageal squamous cell carcinoma (ESCC), and cisplatin resistance, which is not uncommon, is the major barrier to improving patient outcomes. Circular RNAs (circRNAs) are novel noncoding RNAs that are implicated in cancer progression, but their involvement in modulating cisplatin responsiveness in ESCC remains unknown.MethodsBioinformatics analysis was used to profile and identify the circRNAs involved in cisplatin responsiveness in ESCC. The chemosensitive role of cDOPEY2 was confirmed both in vitro and in vivo. The molecular mechanism of cDOPEY2 was investigated by mass spectrometry, immunoprecipitation, and ubiquitination analyses.ResultsWe report that a novel circRNA (cDOPYE2, hsa_circ_0008078) was markedly downregulated in cisplatin-resistant ESCC cells (ESCC-CR) compared with parental chemosensitive cells. Re-expression of cDOPEY2 substantially enhanced the cell-killing ability of cisplatin by augmenting the apoptotic process in ESCC-CR cells, which was achieved by decreasing the abundance of the antiapoptotic protein Mcl-1. Mechanistically, we showed that cDOPEY2 acted as a protein scaffold to enhance the interaction between the cytoplasmic polyadenylation element binding protein (CPEB4) and the E3 ligase TRIM25, which in turn facilitated the ubiquitination and degradation of CPEB4. The increased Mcl-1 expression in ESCC-CR cells was dependent on the binding of CPEB4 to its untranslated mRNA, and depletion of CPEB4 mediated by cDOPEY2 reversed this effect. Rescue experiments confirmed that the critical role of cDOPEY2 in maintaining cisplatin sensitivity was dependent on the depletion of CEPB4 and its downstream target Mcl-1. Clinical and in vivo data further corroborated the significant relevance of cDOPEY2 to cisplatin responsiveness in ESCC.ConclusionsWe provide evidence that cDOPEY2 inhibits CPEB4-mediated Mcl-1 translation by promoting the ubiquitination and degradation of CPEB4 to alleviate cisplatin resistance, indicating that cDOPEY2 may serve as a valuable biomarker and potential therapeutic target in ESCC.