Expression and Significance of N-myc downstream regulated gene 2 in the process of Esophageal Squamous Cell Carcinogenesis.

It has been reported that the expression of tumor suppressor gene N-myc downstream-regulated gene 2 (NDRG2) was significantly reduced in human solid tumors, including esophageal squamous cell carcinoma (ESCC). This study aimed to explore whether the difference of NDRG2 expression exists in different stages of ESCC and provides a basis for the early diagnosis and prognosis of ESCC. Immunohistochemical staining was used to investigate the expression level of NDRG2 in samples from 91 patients with mild-to-moderate dysplasia, early ESCC, and advanced ESCC. The relationship between the expression of NDRG2 and clinicopathological characteristics of the patients was analyzed. The results showed that positive expression rates of NDRG2 in tissues adjacent to early ESCC (76.7%), or from mild-to-moderate dysplasia (74.1%), and early ESCC (83.3%) were significantly higher than in tissue from advanced ESCC (55.9%). The positive expression rate in advanced ESCC was significantly lower than in the other three tissue types (p < 0.05). There was a significant difference (p < 0.05) and correlation (Cramer's V = 0.351, p = 0.019, <0.05) between the expression of NDRG2 and the clinical stage in the 64 patients with ESCC. In conclusion, this study found that the expression of NDRG2 gradually decreased with the progression of esophageal lesions into advanced ESCC. This difference in positive expression rate was more obvious in male patients and patients under 60 years of age. Therefore, the detection of NDRG2 plays an important role in differentiating early ESCC from advanced ESCC.

Aspirin inhibits the proliferation of tobacco-related esophageal squamous carcinomas cell lines through cyclooxygenase 2 pathway.

BACKGROUND: Cigarette smoking has been verified as the risk factor of esophageal squamous cell carcinoma (ESCC). Overexpression of cyclooxygenase 2 (COX-2) is shown in ESCC. The objective of this study was to investigate the effects of cigarette smoking ethanol extract (EE) on the proliferation of the human ESCC cell lines, and to explore the correlation between the proliferation rate of human ESCC cell lines and the expression pattern of COX-2. Whether aspirin can inhibit the proliferation of the ESCC cell lines pretreated with EE, and regulate the mRNA expression levels of COX-2 are also examined. METHODS: Two human ESCC cell lines were selected. EC109 was poorly differentiated and EC9706 was highly differentiated. EC109 and EC9706 were treated with EE and aspirin for different time course. The cell growth of ESCC was measured by MTT reduction assay and the expression of COX-2 was measured by RT-PCR and Western blot analysis. RESULTS: EE promoted the proliferation of EC109 and EC9706 in dose- and time-dependent manners. In the concentration range (10 - 100 microg/ml for EE) and in the time range (24 - 72 hours) after addition of EE, the cell proliferation was prominent in an up-scaled manner respectively. Aspirin could inhibit the proliferation of cell lines EC109 and EC9706, pretreated with EE for 5 hours, in a dose-dependent manner. In the concentration range (0.5 - 8.0 mmol/L for aspirin), the cell growth inhibition was prominent in an up-scaled manner accordingly (P < 0.05). The effect of EE on cell proliferation was correlated with the up-regulation of COX-2 gene. However, the cell growth inhibition of aspirin was correlated with the down-regulation of COX-2 gene. CONCLUSIONS: EE can stimulate the proliferation of human ESCC cell lines EC109 and EC9706, most likely through up-regulating the expression of COX-2. Aspirin can inhibit the proliferation of ESCC cell lines induced by EE, which suggests it may be advantageous in the chemoprevention and therapy of human tobacco-related ESCC. And its effect is likely to be related with modulating COX-2 activity.

Promoter methylation regulates cigarette smoke-stimulated cyclooxygenase-2 expression in esophageal squamous cell carcinoma.

OBJECTIVE: Cigarette smoke extracts (CSE) could promote esophageal squamous cell carcinoma (ESCC) through upregulation of cyclooxygenase-2 (COX-2) expression. Promoter methylation mediates the transcriptional modulation of the COX-2 gene. The aim of the study was to explore whether COX-2 promoter methylation regulated COX-2 expression and functional activity in ESCC exposed to CSE. METHODS: The methylation status of COX-2 promoter in two human ESCC cell lines, EC109 and TE-1, was examined using bisulfite sequencing analysis. COX-2 mRNA and protein expression were detected by reverse-transcription polymerase chain reaction and Western blot. Prostaglandin E2 (PGE2) was examined by enzyme linked immunosorbent assay (ELISA). RESULTS: The promoter was hypermethylated in TE-1 which had a low level of COX-2 expression and was hypomethylated in EC109 with a relatively high level of COX-2 expression. Stimulation by cigarette smoke ethanol extract (EE) resulted in increased COX-2 expression in EC109, but not in TE-1. Treatment with 5-aza-2'-deoxycytidine (5-aza-DC) demethylated the promoter and upregulated COX-2 expression as well as PGE(2) production in TE-1, especially followed by EE stimulation. No significant effect was observed in EC109. CONCLUSION: These findings suggest that promoter methylation may be one of the mechanisms regulating COX-2 expression in ESCC in response to stimulation of CSE.