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Background: Concurrent chemoradiotherapy (CCRT) is the standard treatment for locally advanced esophageal squamous cell carcinoma (ESCC). However, the optimal radiotherapy regimen, particularly in terms of total dose and planned range of irradiation field, remains unclear. This phase III clinical trial aimed to compare the survival benefits between different radiation doses and different target fields., Methods: This trial compared two aspects of radiation treatment, total dose and field, using a two-by-two factorial design. The high-dose (HD) group received 59.4 Gy radiation, and the standard-dose (SD) group received 50.4 Gy. The involved field irradiation (IFI) group and elective nodal irradiation (ENI) group adopted different irradiation ranges. The participants were assigned to one of the four groups (HD+ENI, HD+IFI, SD+ENI and SD+IFI). The primary endpoint was overall survival (OS), and the secondary endpoints included progression-free survival (PFS). The synergy indexwas used to measure the interaction effect between dose and field., Results: The interaction analysis did not reveal significant synergistic effects between the dose and irradiation field. In comparison to the target field, patients in IFI or ENI showed similar OS (hazard ratio [HR] = 0.99, 95% CI: 0.80-1.23, p = 0.930) and PFS (HR = 1.02, 95% CI: 0.82-1.25). The HD treatment did not show significantly prolonged OS compared with SD (HR = 0.90, 95% CI: 0.72-1.11, p = 0.318), but it suggested improved PFS (25.2 months to 18.0 months). Among the four groups, the HD+IFI group presented the best survival, while the SD+IFI group had the worst prognosis. No significant difference in the occurrence of severe adverse events was found in dose or field comparisons., Conclusions: IFI demonstrated similar treatment efficacy to ENI in CCRT of ESCC. The HD demonstrated improved PFS, but did not significantly improve OS. The dose escalation based on IFI (HD+IFI) showed better therapeutic efficacy than the current recommendation (SD+ENI) and is worth further validation., (© 2024 The Author(s). Cancer Communications published by John Wiley & Sons Australia, Ltd on behalf of Sun Yat‐sen University Cancer Center.)

Esophageal squamous cell carcinoma (ESCC) is one of the most lethal cancer types, with a low 5-year survival rate of ~20%. Our prior research has suggested that DNA Polymerase iota (Pol ι), a member of Y-family DNA polymerase, plays a crucial role in the invasion and metastasis of ESCC. However, the underlying mechanism is not well understood. In this study, we utilized ChIP-PCR and luciferase reporter assays to investigate the binding of HIF-1α to the promoter of the Pol ι gene. Transwell, wound healing, and mouse models were employed to assess the impact of Pol ι and HIF-1α on the motility of ESCC cells. Co-immunoprecipitation and Western blot were carried out to explore the interaction between Pol ι and HIF-1α, while qRT-PCR and Western blot were conducted to confirm the regulation of Pol ι and HIF-1α on their downstream targets. Our results demonstrate that HIF-1α activates the transcription of the Pol ι gene in ESCC cells under hypoxic conditions. Furthermore, the knockdown of Pol ι impeded HIF-1α-induced invasion and metastasis. Additionally, we found that Pol ι regulates the expression of genes involved in epithelial-mesenchymal transition (EMT) and initiates EMT through the stabilization of HIF-1α. Mechanistically, Pol ι maintains the protein stability of HIF-1α by recruiting USP7 to mediate the deubiquitination of HIF-1α, with the residues 446-578 of Pol being crucial for the interaction between Pol ι and USP7. Collectively, our findings unveil a novel feedforward molecular axis of HIF-1α- Pol ι -USP7 in ESCC that contributes to ESCC metastasis. Hence, our results present an attractive target for intervention in ESCC., (© 2024. The Author(s).)

TAB182 (also named TNKS1BP1), a binding protein of tankyrase 1, has been found to participate in DNA repair. Our previous study has revealed the involvement of TAB182 in the radioresistance of esophageal squamous cell carcinoma (ESCC) cells. However, whether TAB182 contributes to the ESCC tumorigenesis and progression remains unclear. In this study, we found that highly expressed TAB182 is closely associated with a poor prognosis of patients with ESCC. TAB182 silencing reduced ESCC cell proliferation and invasion in vitro, tumorigenicity and metastasis in vivo. RNA-seq and IP-MS analysis revealed that TAB182 could affect the β-catenin signaling pathway via interacting with β-catenin. Furthermore, TAB182 prevented β-catenin to be phosphorylated by GSK3β and recruited four and a half of LIM-only protein 2 (FHL2), which thereby promoted β-catenin nucleus translocation to result in activation of the downstream targets transcription in ESCC cells. Our findings demonstrate that TAB182 enhances tumorigenesis of esophageal cancer by promoting the activation of the β-catenin signaling pathway, which provides new insights into the molecular mechanisms by which TAB182 accelerates progression of ESCC., (© 2022. The Author(s).)

Background: Radiotherapy has recently become more common for the treatment of esophageal squamous cell carcinoma (ESCC). Radioresistance, on the other hand, continues to be a major issue because it interferes with the effectiveness of ESCC radiation. It has been demonstrated that RAD18, an E3 ubiquitin-protein ligase that regulates translesion DNA synthesis (TLS), is implicated in the regulation of genomic integrity and DNA damage response., Methods: In the present study, immunohistochemical staining and western blotting were utilized to determine RAD18 expression in ESCC tissues and cells. ESCC cell proliferation was determined using a colony formation assay. Immunofluorescence staining, comet assay, and homologous recombination (HR)/non-homologous end-joining (NHEJ) assays were conducted to examine the effect of RAD18 on the DNA damage response in ESCC cells., Results: We found that high RAD18 expression was positively associated with a poorer prognosis in patients with ESCC who received radiotherapy. Downregulation of RAD18 expression significantly increased the sensitivity of ESCC cells to irradiation. Moreover, RAD18 knockdown prolonged the repair kinetics of γH2AX foci and resulted in longer comet tails. Furthermore, loss of RAD18 expression markedly decreased non-homologous end-joining (NHEJ) activity, but it did not affect homologous recombination (HR)-mediated double-strand break repair in ESCC cells. RAD18 upregulated p-DNA-dependent protein kinase complex (p-DNA-PKc) expression in vivo and in vitro., Conclusions: These data indicated that RAD18 may regulate radioresistance by facilitating NHEJ via phosphorylation of DNA-PKcs in ESCC cells, providing a novel radiotherapy target for ESCC., (© 2022 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

Background: Radiotherapy is one of the main strategies for the treatment of esophageal squamous cell carcinoma (ESCC). However, treatment failure often occurs due to the emergence of radioresistance. In this study, we report a key regulator of radiation sensitivity, termed TAB182 that may become an ideal biomarker and therapeutic target to overcome radioresistance., Materials and Methods: By applying qRT-PCR and immunohistochemical staining, the expression of TAB182 was detected in patient tissues. We next assessed the influence of TAB182 downregulation to radiosensitivity using clonogenic survival assay and γ-H2A.X foci analysis in TE-1, TE-10, and radioresistant TE-1R cell lines after ionizing radiation. To unveil the mechanism underlying, TAB182 interacting proteins were identified by mass spectrometry following co-immunoprecipitation. Furthermore, flow cytometry and western blot assay were applied to validate the identified proteins., Results: Our results demonstrated that the expression of TAB182 is higher in cancer tissues than normal tissues and elevated expression of TAB182 correlates with poor outcomes of postoperative radiotherapy. Downregulation of TAB182 sensitized cancer cells to ionizing radiation, particularly in radioresistant TE-1R cells that spontaneously overexpress TAB182. Mechanically, TAB182 interacts with FHL2 to induce G2-M arrest through wiring the CHK2/CDC25C/CDC2 signaling pathway. Finally, overexpression of shRNA-resistant TAB182 restored the checkpoint and radioresistance., Conclusion: TAB182 potentiates the radioresistance of ESCC cells by modulating the G2-M checkpoint through its interaction with FHL2. Thus, TAB182 may become an ideal biomarker and therapeutic target of ESCC radiotherapy., (© 2021 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

As a key regulator of DNA translesion synthesis (TLS) pathway, RAD18 is error-prone and contributes to the accumulation of DNA mutations. We have recently shown that RAD18 is overexpressed in human esophageal squamous cell cancer (ESCC) and acts to promote ESCC progression. The current study aims to understand the molecular mechanism by which RAD18 enhances the invasiveness and metastasis of ESCC cells. We found that RAD18 expression is markedly higher in high T stage ESCCs compared to low T stage groups. Kaplan-Meier analysis showed an inverse correlation between RAD18 expression and patient prognosis. The expression of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9), two vital mediators of cell invasion and proliferation, positively correlated with RAD18 expression in ESCC tissues. Ectopic expression of RAD18 enhanced the motility and invasiveness of ESCC cells as evaluated by wound-healing assays and transwell assays. A xenograft nude mouse model showed that RAD18 promoted the colonization of ESCC cells in vivo. Signaling pathway analysis identified the JNK-MMP cascade as a mediator of RAD18-induced enhancement of ESCC progression. These data demonstrate the underlying mechanism by which RAD18 promotes ESCC progression, suggesting that RAD18 is a promising novel prognostic biomarker and therapeutic target against ESCC., (Copyright © 2018 Elsevier B.V. All rights reserved.)

An aberrantly elevated expression of DNA polymerase ι (Pol ι) is significantly associated with poor prognosis of patients with esophageal squamous cell carcinoma (ESCC), yet the mechanisms behind this phenomenon remain obscure. Based on the RNA-Seq transcriptome and real-time PCR analysis, we identified ETS-1 as a candidate gene involved in Pol ι-mediated progression of ESCC. Wound-healing and transwell assay indicated that downregulation of ETS-1 attenuates Pol ι-mediated invasiveness of ESCC. Signaling pathway analysis showed that Pol ι enhances ETS-1 phosphorylation at threonine-38 through the Erk signaling pathway in ESCC cells. Kaplan-Meier analysis, based on 93 clinical tissue samples, revealed that ETS-1 phosphorylation at threonine-38 is associated with poor prognosis of ESCC patients. The present study thus demonstrates that phosphorylation of ETS-1 is a critical event in the Pol ι-induced invasion and metastasis of ESCC., (© 2017 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)

Esophageal squamous cell carcinoma (ESCC) has one of the highest mortality rates worldwide. AU-rich element RNA-binding factor 1 (AUF1) is an established RNA-binding protein. AUF1 influences the process of development, apoptosis and tumorigenesis via interacting with adenylate-uridylate rich elements (AREs) bearing mRNAs. However, the clinical relevance of AUF1 and its biological function in ESCC progression have not been reported. In the present study, we first investigated the expression of AUF1 in the ESCC tissue samles and normal samples. We found a significantly higher expression of AUF1 in ESCC tissues than that in normal tissues and tumor adjacent tissues. The expression of AUF1 correlated with ESCC stage (P=0.011) and marginally correlated with lymph node metastasis (P=0.055) of ESCC patients. Silencing of AUF1 by an siRNA inhibited the proliferation and enhanced the apoptosis of ESCC cells. mRNA profiling by microarray analysis revealed that AUF1 knockdown affected 285 genes (fold change ≥2) that function in multiple pathways. GTP cyclohydrolase I (GCH1), the rate limiting enzyme for BH4 synthesis, was found to be downregulated. One of the AU-rich elements in the 3'UTR of GCH1 was found to be responsive to AUF1 expression by luciferase assay. Knockdown of GCH1 suppressed cell proliferation and colony formation of ESCC cells. The expression of AUF1 significantly correlated with that of GCH1 in ESCC tissues. Taken together, we demonstrated the overexpression of AUF1 in esophageal carcinoma and identified GCH1 as AUF1's effector for the proliferation of ESCC cells.

DNA polymerase iota (Pol ι) is an error-prone DNA polymerase involved in translesion DNA synthesis (TLS) that contributes to the accumulation of DNA mutations. We recently showed that Pol ι is overexpressed in human esophageal squamous cell cancer (ESCC) tissues which promotes ESCC' progression. The present study was aimed at investigating the molecular mechanisms by which Pol ι enhances the invasiveness and metastasis of ESCC cells. We found that the expression of Pol ι is significantly higher in ESCCs with lymph node metastasis compared to those without lymph node metastasis. Kaplan-Meier analysis revealed an inverse correlation between Pol ι expression and patient prognosis. The expression levels of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9), two essential regulators of cells' invasiveness, were positively associated with Pol ι expression in ESCC tissues. Ectopic expression of Pol ι enhanced the motility and invasiveness of ESCC cells as evaluated by wound-healing and transwell assays, respectively. A xenograft nude mouse model showed that Pol ι promotes the colonization of ESCC cells in the liver, lung and kidney. Signaling pathway analysis identified the JNK-AP-1 cascade as a mediator of the Pol ι-induced increase in the expression of MMP-2/9 and enhancement of ESCC progression. These data demonstrate the underlying mechanism by which Pol ι promotes ESCC progression, suggesting that Pol ι is a potential novel prognostic biomarker and therapeutic target for ESCC., Competing Interests: The authors have no conflicts of interest.

Objective: To investigate the effect of RAD18-siRNA on cell proliferation and chemotherapy sensitivity of esophageal squamous cell carcinoma (ESCC) ECA-109 cells. Methods: RAD18-siRNA was transfected into human ECA-109 cells by Lipofectamine 3000. Quantitative PCR and Western blot were performed to detect RAD18 and CyclinD1 expression; CCK-8 assay was used to determine cell proliferation and chemotherapy drug sensitivity; flow cytometry was used to determine cell cycle. Correlation between RAD18 and CyclinD1 mRNA expression was analyzed by Pearson's correlation. Results: Compared with non-transfected cells, the expression of RAD18 in RAD18-siRNA group was significantly decreased ( P <0.05). The cell proliferation was inhibited ( P <0.05) and the cell number of G1 phase was increased, G2/M phase cells decreased ( P <0.05) in RAD18-siRNA group. After treatment with different concentrations of cisplatin or 5-FU, the survival rate of the two cell groups was reduced (all P <0.05), and the IC50 of RAD18-siRNA group was significantly lower than that of non-transfected group ( P <0.05). The mRNA expression of RAD18 was positively correlated with CyclinD1 expression in ESCC tissues( r =0.478, P <0.01). Conclusion: Down-regulated expression of RAD18 can decrease the cell proliferation and increase chemo-sensitivity of ESCC cells, and CyclinD1 may participate in the process.

Protein reversionless 3-like (REV3L), the catalytic subunit of DNA polymerase (pol) ζ, is well known to participate in error-prone translesion synthesis (TLS) with less stringent and lower processivity. Recent evidence has demonstrated that REV3L is involved in carcinogenesis and tumor progression. However, the function of REV3L remains unclear in esophageal squamous cell carcinoma (ESCC). In the present study, we examined REV3L expression in ESCC tissues and its association with clinicopathological parameters. REV3L was found to be significantly upregulated and correlated with lymph node metastasis and clinical stage in the ESCC tissues. To further investigate the potential role of REV3L in esophageal cancer, stable ESCC cell lines with suppression of REV3L expression were established. Downregulation of REV3L expression led to a decrease in cell proliferation and invasive capacity partly through suppression of cyclin D1 and survivin expression, and an increase in cellular sensitivity to 5-fluorouracil (5-FU) by induction of G1 phase arrest and apoptosis. Therefore, REV3L plays an important role in ESCC progression and chemoresistance, and is a potential diagnostic marker and therapeutic target for ESCC.

Esophageal squamous cell carcinoma (ESCC), one of the most common gastrointestinal tumors, is known for its high mortality rate. microRNAs (miRNAs) have been reported to play important regulatory roles in cancer metastasis and progression. miR-34a has been demonstrated to be associated with the development of and metastasis in certain types of cancer via various target genes, but its function and targets in ESCC are unknown. The aim of this study was to examine whether the expression of miR-34a was significantly decreased in ESCC tissues, compared with normal esophageal tissues using RT-PCR and western blot analysis. The results showed that miR-34a overexpression increased apoptosis and decreased clonogenic formation, but inhibited invasion and migration in ESCC cells by suppressing MMP-2 and -9 expression. Yin Yang-1 (YY1), a widely distributed transcription factor that belongs to the GLI-Kruppel class of zinc finger proteins, was found to be a direct target of miR-34a in ESCC cell lines. Rescue experiments indicated that the suppressive effect of miR-34a on invasion and migration was mediated by activating YY1 expression. Results of the present study showed that miR-34a is associated with ESCC migration and provides a potential therapeutic and diagnostic target for ESCC.

DNA polymerase iota (Polι) can repair several types of DNA damage but has extremely low fidelity. Previous studies have shown an aberrantly elevated Polι expression in human esophageal squamous cell cancer tissues. However, there were few reports describing the role of Polι in esophageal cancer progression. Based on Real-time PCR assay, we found Polι expression was up-regulated in esophageal cancer tissues compared to adjacent normal tissues and overexpression of Polι was correlated to lymph node metastasis. Clonogenic assay and transwell chamber assay showed that overexpression of Polι had higher clongenic capability and invasive tendency in human esophageal squamous cell cancer cells. Expression of cyclin D1, an important cell cycle regulator, was found to be associated with that of Polι in tissue samples and cancer cells as analyzed by real-time PCR, immunohistochemistry, Western blotting and immunofluorescence assay. Flow cytometry analysis further showed that cell cycle distribution was altered in Polι overexpressing cells. These results indicated that expression of Polι correlates significantly with tumor proliferation and invasion. We conclude that Polι is involved in the degree of aggressiveness of human esophageal squamous cell cancer.

Background/aims: This study investigated the clinical relevance and biological function of paired box gene 2 (PAX2) in esophageal squamous cell carcinoma (ESCC)., Methods/results: Results showed that PAX2 expression was significantly increased in tumor tissues and that its expression correlated with the ESCC stage (P = 0.001), lymph node metastasis (pN, P = 0.019) and lymphatic invasion (P = 0.005) in 120 ESCC tissue specimens by immunohistochemistry. Furthermore, PAX2 overexpression resulted in markedly reduced cell proliferation but increased metastasis capacity in ESCC TE-1 and Eca-109 cells. Knockdown of PAX2 expression with a short hairpin RNA confirmed a role in the promotion of metastasis in ESCC cells. mRNA microarray screening revealed that PAX2 overexpression affected multiple genes that function in multiple pathways. Interleukin-5 (IL-5), which was induced by PAX2 and has been shown to promote tumor metastasis, was further studied in greater detail. Two PAX2 binding sites were identified in the IL-5 promoter, and PAX2 was observed to stimulate IL-5 promoter activity and IL-5 expression in esophageal cancer cells. Chromatin immunoprecipitation (ChIP) confirmed the direct binding of PAX2 in the IL-5 promoter. The expression of PAX2 mRNA significantly correlated with that of IL-5 in normal esophageal and ESCC tissues., Conclusion: These findings demonstrate that PAX2 is overexpressed in esophageal carcinoma and IL-5 is identified as PAX2's effector for metastasis., (© 2015 S. Karger AG, Basel.)

The present study investigated the transcriptional regulation of low-fidelity translesion DNA synthesis (TLS) polymerases in human esophageal carcinoma. Significantly higher mRNA expression of polymerase zeta (Polξ), RAD18, polymerase iota (Polι), and polymerase kappa (Polκ) was found in esophageal carcinomas. The increased expression of Polι in tumor samples was further confirmed by immunohistochemistry. The promoter of POLI that encodes Polι was found to be hypomethylated, although the overexpression of this gene was unlikely to be associated with methylation in tumors. We further identified Sp1 and Oct-1 binding sites present in the POLI promoter. We observed that the binding affinity of Sp1 to the POLI promoter was significantly increased in cancerous tissues and that Sp1 activated POLI gene transcription in cultured cell lines. The present study demonstrates overexpression of the TLS genes in esophageal carcinoma and identifies a key role for Sp1 in upregulating POLI gene expression., (© 2012 Japanese Cancer Association.)

Vascular endothelial growth factor C (VEGF-C) is a key regulator of angiogenesis and lymphangiogenesis. VEGF-C is also implicated in the development of esophageal cancer. We investigated the mRNA levels of VEGF-C and its receptors in 38 esophageal squamous cell carcinoma specimens (ESCCs) and matched adjacent normal esophageal tissues via real-time PCR. The mRNA levels of VEGF-C, VEGFR-2 and VEGFR-3 were significantly upregulated in ESCCs versus respective side normal tissues. To explore the influence of VEGF-C on esophageal cancer progression, the expression of VEGF-C was manipulated in esophageal cancer cell lines TE-1 and Eca-109. VEGF-C transcription, translation and secretion were significantly enhanced in cells stably transfected with a VEGF-C overexpression vector or attenuated in VEGF-C shRNA-transfected cell lines. In vitro, TE-1 cells stably transfected with a VEGF-C overexpression vector exhibited an increased rate of cell proliferation, migration and focus formation, whereas knockdown of VEGF-C inhibited cell proliferation, migration and focus formation. Similar results were obtained for Eca-109 cells. VEGF-C mediated biological function through transcription of CNTN-1, which is implicated in tumor invasion and metastasis. The expression of VEGF-C was correlated with that of CNTN-1 and cell proliferation and migration induced by VEGF-C were reversed by silencing of CNTN-1. In addition, nude mice inoculated with VEGF-C shRNA-transfected cells exhibited a significantly decreased tumor size in vivo via reduced VEGFR-2 and VEGFR-3 phosphorylation and microvessel formation. VEGF-C upregulation may be involved in esophageal tumor progression. Vector-based RNA interference (RNAi) targeting VEGF-C is a potential therapeutic method for human esophageal carcinoma., (Copyright © 2011 Elsevier Ltd. All rights reserved.)