A ZBP1 isoform blocks ZBP1-mediated cell death.

ZBP1 is an interferon (IFN)-induced nucleic acid (NA) sensor that senses unusual Z-form NA (Z-NA) to promote cell death and inflammation. However, the mechanisms that dampen ZBP1 activation to fine-tune inflammatory responses are unclear. Here, we characterize a short isoform of ZBP1 (referred to as ZBP1-S) as an intrinsic suppressor of the inflammatory signaling mediated by full-length ZBP1. Mechanistically, ZBP1-S depresses ZBP1-mediated cell death by competitive binding with Z-NA for Zα domains of ZBP1. Cells from mice (Ripk1D325A/D325A) with cleavage-resistant RIPK1-induced autoinflammatory (CRIA) syndrome are alive but sensitive to IFN-induced and ZBP1-dependent cell death. Intriguingly, Ripk1D325A/D325A cells die spontaneously when ZBP1-S is deleted, indicating that cell death driven by ZBP1 is under the control of ZBP1-S. Thus, our findings reveal that alternative splicing of Zbp1 represents autogenic inhibition for regulating ZBP1 signaling and indicate that uncoupling of Z-NA with ZBP1 could be an effective strategy against autoinflammations.

Comparison of elective nodal irradiation and involved-field irradiation in esophageal squamous cell carcinoma: a meta-analysis.

It remains controversial whether radical radiotherapy in patients with esophageal squamous cell carcinoma (ESCC) still requires elective nodal irradiation (ENI), or only involved-field irradiation (IFI). In this study, a meta-analysis was conducted to compare ENI and IFI in the treatment of ESCC, in order to provide guidance for clinical practice. Literature on the use of ENI and IFI in the treatment of ESCC was retrieved, and the last access date was 31 December 2017. A meta-analysis was performed to evaluate the relative advantages and disadvantages of using ENI and IFI. Ten studies, involving a total of 1348 patients, were included in this analysis; of these, 605 patients underwent radiotherapy only, and 743 underwent radiochemotherapy. There was no significant difference in the 1-, 2- or 3-year local control rates between ENI and IFI, or in the 1-, 2- or 3-year overall survival rates. However, the incidences of ≥Grade 3 acute esophagitis and pneumonia were significantly lower in the IFI group. There were no differences in the rates of ≥Grade 3 myelosuppression or of out-field recurrence or metastasis between these two groups. Thus, neither local control rates nor overall survival rates differed significantly between the ENI and IFI groups, but in the latter group, incidences of severe radiation esophagitis and pneumonia were significantly lower. IFI was not associated with an increase in out-field recurrence or metastasis.

Effect of nitric oxide on esophageal cancer cell line TE-1.

OBJECTIVE: To investigate the radiosensitizing effect of nitric oxide (NO) combined with radiation on esophageal cancer cell line TE-1. METHODS: Methyl thiazolyl tetrazolium (MTT) assay was used to assess the effects of NO and radiation on TE-1 cells regarding inhibition of cell proliferation. Flow cytometry was used to examine the effect of NO and radiation on cell apoptosis and cycle. Reverse transcription polymerase chine reaction and Western blot were used to evaluete the effect of NO on mRNA and protein expression of manganese superoxide dismutase (MnSOD). RESULTS: NO inhibited the proliferation of TE-1 cells while significantly enhancing their radiosensitivity. The application of NO combined with radiation significantly increased the apoptosis rate and G2/M phase proportion of TE-1 cells, with substantial decreases in the MnSOD mRNA and protein expression levels. CONCLUSIONS: NO reduces the MnSOD mRNA and protein expression levels by affecting TE-1 cell cycle, further inhibiting the apoptosis of esophageal cancer cells and enhancing the killing effect of radiation on esophageal cancer cells.

Characteristics of recurrence after radical esophagectomy with two-field lymph node dissection for thoracic esophageal cancer.

Postoperative radiotherapy has shown positive efficacy in lowering the recurrence rate and improving the survival rate in cases involving lymph node (LN) metastasis. However, the radiotherapy target volume remains controversial. Certain published studies have paid more attention to LNs found to be affected during surgery, while little effort has been made to study the LN metastatic pattern following surgery and its influence on the determination of the target volume of postoperative radiotherapy. In this study, the locoregional recurrence of esophageal squamous cell cancer was examined in 134 patients receiving radical surgery with two-field lymph node dissection from 2004 to 2009. In the 134 cases of recurrence, LN metastasis occurred in 126 patients (94.0%) while 13 patients (9.7%) developed anastomotic recurrence and 5 patients (3.7%) experienced tumor bed recurrence. The difference among the groups was statistically significant (P= 0.000). In the 126 cases with lymph node metastasis, the mediastinal metastasis rate (80.2%) was significantly higher compared with the rate of supraclavicular metastasis and abdominal metastasis (P= 0.000). A significant difference was identified between right and left supraclavicular LN metastasis (31.7% vs 16.7%, P= 0.005). Furthermore, the difference between the metastatic rates in the upper (73.8%), middle (39.7%) and lower mediastinum (1.6%) was statistically significant (P=0.000). Nevertheless, no significant correlation between the rate of LN metastasis was observed in the supraclavicular, mediastinal and abdominal regions for upper, middle and lower thoracic carcinomas (P= 0.404, P= 0.718 and P= 0.169, respectively). Based on our data, LN metastasis is the major locoregional recurrence pattern for esophageal squamous cell cancer following radical surgery. The high-risk lymphatic drainage areas include the supraclavicular nodes, recurrent laryngeal nerve nodes, azygos nodes and subcarinal nodes.

HIF-1α contributes to hypoxia-induced invasion and metastasis of esophageal carcinoma via inhibiting E-cadherin and promoting MMP-2 expression.

Hypoxia-inducible factor-1α (HIF-1α) has been found to enhance tumor invasion and metastasis, but no study has reported its action in esophageal carcinoma. The goal of this study was to explore the probable mechanism of HIF-1α in the invasion and metastasis of esophageal carcinoma Eca109 cells in vitro and in vivo. mRNA and protein expression of HIF-1α, E-cadherin and matrix metalloproteinase-2 (MMP-2) under hypoxia were detected by RT-PCR and Western blotting. The effects of silencing HIF-1α on E-cadherin, MMP-2 mRNA and protein expression under hypoxia or normoxia were detected by RT-PCR and Western blotting, respectively. The invasive ability of Eca109 cells was tested using a transwell chambers. We established an Eca109-implanted tumor model and observed tumor growth and lymph node metastasis. The expression of HIF-1α, E-cadherin and MMP-2 in xenograft tumors was detected by Western blotting. After exposure to hypoxia, HIF-1α protein was up-regulated, both mRNA and protein levels of E-cadherin were down-regulated and MMP-2 was up-regulated, while HIF-1α mRNA showed no significant change. SiRNA could block HIF-1α effectively, increase E-cadherin expression and inhibit MMP-2 expression. The number of invading cells decreased after HIF-1α was silenced. Meanwhile, the tumor volume was much smaller, and the metastatic rate of lymph nodes and the positive rate were lower in vivo. Our observations suggest that HIF-1α inhibition might be an effective strategy to weaken invasion and metastasis in the esophageal carcinoma Eca109 cell line.

Bidirectional regulation of manganese superoxide dismutase (MnSOD) on the radiosensitivity of esophageal cancer cells.

The mitochondrial antioxidant protein manganese superoxide dismutase (MnSOD) may represent a new type of tumor suppressor protein. Overexpression of the cDNA of this gene by plasmid or recombinant lentiviral transfection in various types of cancer leads to growth suppression both in vitro and in vivo. We previously determined that changes in MnSOD expression had bidirectional effects on adriamycin (ADR) when combined with nitric oxide (NO). Radiation induces free radicals in a manner similar to ADR, so we speculated that MnSOD combined with NO would also have a bidirectional effect on cellular radiosensitivity. To examine this hypothesis, TE-1 human esophageal squamous carcinoma cells were stably transfected using lipofectamine with a pLenti6-DEST plasmid containing human MnSOD cDNA at moderate to high overexpression levels or with no MnSOD insert. Blastidicin-resistant colonies were isolated, grown, and maintained in culture. We found that moderate overexpression of MnSOD decreased growth rates, plating efficiency, and increased apoptosis. However, high overexpression increased growth rates, plating efficiency, and decreased apoptosis. When combined with NO, moderate overexpression of MnSOD increased the radiosensitivity of esophageal cancer cells, whereas high MnSOD overexpression had the opposite effect. This finding suggests a potential new method to kill certain radioresistant tumors and to provide radioresistance to normal cells.

[Effect of HIF-1α and its mechanism on invasion and metastasis of esophageal carcinoma Eca109 cells in vitro and in vivo].

AIM: To investigate the effects of HIF-1α by RNAi on invasion and metastasis of esophageal carcinoma Eca109 cells in vitro and in vivo, in order to explore its probable mechanism. METHODS: CoCl(2); was used to mimic tumor hypoxic microenvironment. mRNA and protein levels of HIF-1α, E-cadherin and MMP-2 under hypoxia were detected by RT-PCR and immunohistochemistry. The effects of silencing HIF-1α by RNAi on HIF-1α, E-cadherin and MMP-2 mRNA were detected by RT-PCR. The effect of RNAi on invasion and metastasis were tested by cell scratch assay and transwell chambers. The Eca109-implanted nude mouse model was established, and the effects of HIF-1αon tumor growth and lymphoid node metastasis were observed. The expressions of HIF-1α, E-cadherin and MMP-2 in transplanted tumors were detected by Western blot, and the effects of HIF-1α on tumor growth, invasion and metastasis in vitro and in vivo were analyzed. RESULTS: Hypoxia up-regulated HIF-1α protein, mRNA and protein levels of E-cadherin down-regulated, and MMP-2 up-regulated, while had no effect on HIF-1α mRNA . RNAi could silencing HIF-1α effectively, and inhibited E-cadherin or MMP-2 decreased or increased, respectively. The migration and the number of invading cells decreased (P<0.05) after silencing HIF-1α by RNAi. The tumor volume was much smaller, lymph node metastasis rate lower as well in vivo (P<0.05). CONCLUSION: Via its effects on E-cadherin and MMP-2, HIF-1α regulate the growth, invasion and metastasis of Eca109 cells in vitro and in vivo.