Clinicopathological Significance Of Bmi-1and Mel-18Expression In Colorectal Cancer

Colorectal cancer is one of the most common malignancy in theworld.The knowledge of emergence gained insight into colorectal tumorinitiation and progression.However,the exact mechanism is still poorlyunderstood. Polycomb group genes, as one kind of epigenetically silencedtumor suppressor genes, play key roles in the development of multiple systemsand the regulation of Cell cycle.Bmi-1(B-cell specific moloney murineleukemia virus insert on site1,Bmi-1) is highly similar to Mel-18. Both belongto comb gene family(the polycomb of the genes,PcG).The combined detectionof Bmi-1and Mel-18expression in gastric cancer has been reported.Thecombined detection of Bmi-1and Mel-18expression in colorectal cancer andrelated research at home and abroad has so far not been reported.Objective:To study the expression of Bmi-1and Mel-18in experimentalgroup(malignant colorectal tissue,n=50),control group(benign colorectaltissue,n=20)and normal control group(normal colorectal tissue,n=20)at mRNAand protein level,and investigate their correlations.Further more,the relationsof their expressions with clinical and pathological features were analyzed.Methods:The experiment set up three experimental groups, namely experimentalgroup,control group and normal control group.The gene and proteinexpression in three experimental groups were determined by RT-PCR andimmunohistochemical method, respectively. The Bmi-1and Mel-18expression status were analyzed at gene and protein level. And analysis of thelevel of expression of experimental group, gender, age, tumor size,tumor site, differentiation degree,lymph node metastasis,clinical stage,clinicalpathological factors as well as the correlation of Bmi-1and Mel-18expression.Results:The mRNA and protein levels of Bmi-1were significantly highest inexperimental group than that in control group and normal control group (allp<0.05), and that in control group and normal control group existed significantdifference(p<0.05).The mRNA and protein levels of Mel-18were significantlylowest in experimental group than that in control group and normal controlgroup (all p<0.05),but that in control group and normal control group were nosignificance difference(P>0.05).The mRNA and protein expression of Bmi-1and Mel-18were negatively related in experimental group (respectivelyr=-0.551，P <0.0001；r=-0.579，P <0.0001).The mRNA and protein levels ofBmi-1were closely related to lymphatic metastasis and clinical stages (allp<0.05), but were irrelevant to patients’gender,age,tumor size,tumor site,differentiation degree (all P>0.05).The Mel-18mRNA was closely related tolymphatic metastasis and clinical stages (all p<0.05), but was irrelevant topatients’gender,age,tumor size,tumor site,differentiation degree(allP>0.05).The Mel-18protein was not related to clinical and pathologicalfeatures（all P>0.05).Conclusion:1Bmi-1of high expression and Mel-18low expression may beassociated with malignant colorectal tissue carcinogenesis developmentInvasion and metastasis.2Bmi-1and Mel-18expression were negatively correlated in malignantcolorectal tissue.3Combined detection of Bmi-1and Mel-18on the malignant biologicalbehavior of malignant colorectal tissue might judge significance.