Blockage of Nrf2 suppresses the migration and invasion of esophageal squamous cell carcinoma cells in hypoxic microenvironment.

Nuclear factor erythroid-2-related factor 2 (Nrf2) is a critical cell protector by inducing phase two detoxifying and anti-oxidant enzymes in normal cells. But recently, numerous evidence show Nrf2 may play the same beneficial roles toward the cancer cells. Nrf2 is found upexpressed in lots of cancers and promote the proliferation and drug resistance. But studies about the role of Nrf2 in the metastases are few. It has been testified that the tumor cells are under hypoxic conditions. As an important anti-oxidant element, the expression of Nrf2 may be upregulated, which in turn promotes the tumor invasion and metastases in the hypoxic microenvironment. Our team found the expression of Nrf2 correlated with the lymph node metastasis of esophageal squamous cell carcinoma by pathological sections of esophageal carcinoma patients. Further, the mechanism beneath it was studied in this paper. It was hypothesized that the hypoxia microenvironment transformed Nrf2 a friend to a foe. First, Eca-109 cells were treated with different concentration of CoCl2 . Western blot and quantitative reverse transcription-polymerase chain reaction showed that with the increase of the concentration of CoCl2 , the expression levels of Nrf2 and hypoxia-inducible factor-1 (HIF-1) alpha were upregulated simultaneously. By analyzing the data, a significant correlation between Nrf2 and HIF-1 alpha in the protein levels was found. Further, blockage of Nrf2 mediated by shRNA suppressed the expression of HIF-1 alpha, hemeoxygenase-1 (HO-1), and matrix metalloproteinase 2 but enhanced the expression of E-cadherin. In addition, the results of wound healing and invasion assay-verified blockage of Nrf2 suppressed the migration and invasion. So it was suggested that blockage of Nrf2 repressed the migration and invasion of esophageal squamous cell carcinoma cells in the hypoxic microenvironment. HIF-1 alpha might be one of the downstream genes of Nrf2 regulated through Nrf2/HO-1 axis in the CoCl2 model. Nrf2 inhibition suppressed matrix metalloproteinase 2 and enhanced E-cadherin partly through HIF-1 alpha way.

Shen H ，Yang Y ，Xia S ，Rao B ，Zhang J ，Wang J ... -  《-》

Hypoxia suppresses E-cadherin and enhances matrix metalloproteinase-2 expression favoring esophageal carcinoma migration and invasion via hypoxia inducible factor-1 alpha activation.

The goal of this study was to explore the molecular mechanism of hypoxia inducible factor-1 alpha (HIF-1 alpha) action on migration and invasion of esophageal carcinoma cells. We used cobalt chloride (CoCl(2) ) to mimic tumor hypoxic microenvironment and analyzed the expressions of E-cadherin, matrix metalloproteinase-2 (MMP-2), and HIF-1 alpha in esophageal carcinoma cells under hypoxia by reverse transcription polymerase chain reaction and Western blotting. To analyze the function of HIF-1 alpha in Eca109 and TE1 cells, we established stable HIF-1 alpha knockdown cells using small interfering RNA. Blocking effect was detected by Western blotting. The concentrations of MMP-2 protein in the conditioned medium were also determined by enzyme-linked immunosorbent assay. Wound-healing and cell invasion assay were used to evaluate the migration and invasion of esophageal carcinoma cells. After exposure to hypoxia, expressions of HIF-1 alpha protein in Eca109 and TE1 cells were upregulated, both mRNA and protein levels of E-cadherin were downregulated, and MMP-2 were upregulated (P < 0.05), whereas HIF-1 alpha mRNA had no significant change (P > 0.05). Small interfering RNA could block HIF-1 alpha effectively under hypoxia, then enhanced E-cadherin expression and inhibited MMP-2 expression, respectively. Furthermore, expression of HIF-1 alpha protein was stable even though MMP-2 repressed by BB2516. Compared with that in normoxia, Snail expression was enhanced when Eca109 or TE1 cells exposed to hypoxia. Once HIF-1 alpha blocked, Snail expressions were inhibited accordingly. Wound recovery and the number of invading cells decreased (P < 0.05) after HIF-1 alpha blocked. The hypoxia suppresses E-cadherin expression and enhances MMP-2 expression favoring esophageal carcinoma migration and invasion via HIF-1 alpha activation. Our observations suggest that HIF-1 alpha inhibition might be an effective strategy to weaken the migration and invasion of esophageal carcinoma cells.

Jing SW ，Wang YD ，Chen LQ ，Sang MX ，Zheng MM ，Sun GG ，Liu Q ，Cheng YJ ，Yang CR ... -  《-》

HIF-1α induces VE-cadherin expression and modulates vasculogenic mimicry in esophageal carcinoma cells.

Tang NN ，Zhu H ，Zhang HJ ，Zhang WF ，Jin HL ，Wang L ，Wang P ，He GJ ，Hao B ，Shi RH ... -  《-》

Twist may be associated with invasion and metastasis of hypoxic NSCLC cells.

Wei L ，Sun JJ ，Cui YC ，Jiang SL ，Wang XW ，Lv LY ，Xie L ，Song XR ... -  《-》

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

Jing SW ，Wang YD ，Zheng MM ，Sun GG ，Liu Q ，Cheng YJ ，Yang CR ... -  《-》