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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.)

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. [ABSTRACT FROM AUTHOR]