Expression and clinicopathological significance of Mel-18 and Bmi-1 mRNA in gastric carcinoma

Background: the polycomb group (pcg) genes are a class of regulators responsible for maintaining homeotic gene expression throughout cell division. pcg expression is deregulated in some types of human cancer. both bmi-1 and mel-18 are of the key pcg proteins. we investigate the expression and clinicopathological roles of mel-18 and bmi-1 mrna in gastric cancer. methods. the expression of mel-18 and bmi-1 in a series of 71 gastric cancer tissues and paired normal mucosal tissues distant from the tumorous lesion was assayed by quantitative real time rt-pcr. the correlation between mel-18 and bmi-1 mrna expression,and between mel-18 or bmi-1 mrna level and clinicopathological characteristics were analyzed. results. expression of mel-18 and bmi-1 genes was variably detected,but overexpression of bmi-1 mrna and decreased expression of mel-18 mrna were the most frequent alteration. in addition,the expression of bmi-1 and mel-18 mrna inversely correlates in gastric tumors. moreover,a significant positive correlation between bmi-1 overexpression and tumor size,depth of invasion,or lymph node metastasis,and a significant negative correlation between mel-18 low-expression with lymph node metastasis or the clinical stage were observed. conclusion. our data suggest that mel-18 and bmi-1 may play crucial but opposite roles in gastric cancer. decreased mel-18 and increased bmi-1 mrna expression was associated with the carcinogenesis and progression of gastric cancer. it is possible to list bmi-1 and mel-18 as biomarkers for predicting the prognosis of gastric cancer. © 2010 lu et al; licensee biomed central ltd.