As one of major epigenetic changes responsible for tumor suppressor gene inactivation in the development of cancer, promoter hypermethylation was proposed as a marker to define novel tumor suppressor genes. In the current study we identified ZIC1 (Zic family member 1, odd-paired Drosophila homolog) as a novel tumor suppressor gene silenced through promoter hypermethylation in gastric cancer, the second leading cause of cancer death worldwide. In all of gastric cancer cells lines examined, ZIC1 expression was downregulated and such downregulation was accompanied with the hypermethylation of ZIC1 promoter. Demethylation treatment with 5-aza-2'-deoxycytidine (Aza) reversed ZIC1 downregulation, highlighting the importance of promoter methylation to ZIC1 downregulation in gastric cancer cells. Notably, ZIC1 expression was significantly downregulated in primary gastric carcinoma tissues in comparison with non-tumor adjacent gastric tissues (p<0.01). Accordingly, promoter methylation of ZIC1 was frequently detected in primary gastric carcinoma tissues (94.6%, 35/37) but not normal gastric tissues, indicating that promoter hypermethylation mediated ZIC1 downregulation may play an important role in gastric carcinogenesis. Indeed, ectopic expression of ZIC1 led to the growth inhibition of gastric cancer cells through the induction of S-phase cell cycle arrest (p<0.01). Our results revealed ZIC1 as a novel candidate tumor suppressor gene downregulated through promoter hypermethylation in gastric cancer.

Background/Objective:Dietary patterns, which represent a complex integration of food and nutrients, have been used to explore the association between dietary factors and the risk of oesophageal cancer. However, the association remains unclear. This systematic review was performed to evaluate the relationship between dietary patterns and oesophageal squamous cell carcinoma (ESCC) by pooling available data from existing studies.Methods:Pertinent articles published up to the end of 2013 were systematically searched and retrieved. The most common dietary patterns with high loadings of foods/nutrients were selected. Adjusted odds ratios (ORs) were derived by comparing the highest with the lowest categories of dietary pattern scores and by using a random-effect model. Heterogeneity was tested using I2 statistic.Results:From nine available case–control studies, in which smoking and other confounding factors were considered, three most common dietary patterns were selected: western pattern, healthy pattern, and drinker/alcohol pattern. Healthy pattern was significantly associated with a decreased risk of ESCC (OR=0.36, 95% confidence interval (CI): 0.23, 0.49); drinker/alcohol pattern was related to a significantly increased risk (OR=2.34, 95% CI: 1.22, 3.45), while no significant association with western pattern was observed (OR=1.29, 95% CI: 0.83, 1.75).Conclusions:Based on available studies, though limited in number, this meta-analysis suggests that some dietary patterns may be associated with the risk of ESCC.

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