| B lymphoma Mo-MLV insertion region1homolog (Bmi-1) is a member ofthe Polycomb family of proteins that function by repressing the transcription oftheir target genes via an epigenetic mechanism. Bmi-1regulates cellularprocesses including cell cycle progression, apoptosis and senescence, and isessential for maintaining the ability of neural and hematopoietic stem cells toself-renew, and plays an important role in the embryonic development. Recently,lots of studies demonstrate that Bmi-1is dysregulated in various cancers, andits upregulation strongly correlates with an invasive phenotype and poorprognosis in patients with cancer. Several studies show that Bmi-1isoverexpressed in hepatocellutar carcinoma, but its role in the development ofhepatocellutar carcinoma is controversial. Some work show that Bmi-1ismainly expressed in the early and well differentiated HCC, and its expression isnot correlates with the progression of HCC. However, some other studies show that the extent of Bmi-1is significantly higher in pooly differentiated HCC andrelatively low in well-differentiated HCC. Bmi-1is associated with theprogression and aggressive malignant biological behavior of HCC. The tworesearch results are contradictory. In order to clarify the relationship betweenBmi-1and the invasion and metastasis of HCC, we designed and carried out thefollowing experiments:Objectives：To detect the expression of Bmi1in the tissues of HCC and toinvestigate the effect of Bmi-1gene on invasion and metastasis of humanhepatocellular carcinoma cell MHCC97-H. In oder to provide a new idea for theinvasion and metastasis of HCC.Methods: We detected the expression of Bmi1in46cases of HCC tissuesand paraneoplastic hepatic tissues and16normal liver tissues byimmunohistochemical and analysed the relationship between Bmi-1expressionand the clinical parameters of HCC. The chemically-synthetic siRNA duplexestargeting Bmi-1(Bmi-1-siRNA) was transiently transfected into MHCC97-Hcell which have high metastatic potential by lipofectamine2000. Thetransfection efficiency was observed by flow cytometry (FCM). Bmi-1mRNAand protein expression levels were detected by real time RT-PCR and Westernblot, respectively. The effects of Bmi-1knockdown on cell invasion andmigration were analyzed by Transwell chamber model, respectively. Wedetected the E-cadhrin and PTEN mRNA level by real time RT-PCR.Results: Immunohistochemical showed that the Bmi1expression wasincreased in HCC, and was not correlated with age, gender, tumor size，TNMstage (P＞0.05). However, the expression of Bmi1in HCC was associated withthe histological differentiation, the Bmi1expression in poor differentiated HCCspecimens were higher than that in well differentiated HCC specimens (P＜ 0.05). And the expression of Bmi1in HCC was associated with portalinvolvement(P＜0.05). The siRNA targeting Bmi-1(Bmi-1-siRNA) wastransiently transfected into MHCC97-H cell. In the results of flow cytometry(FCM), the transfection efficiency of Bmi-1-siRNA was91%. Compared withblank group and control-siRNA group, Bmi-1-siRNA can effectively inhibitBmi-1mRNA (F=56.199, P <0.05) and protein expression in Bmi-1-siRNAgroup. Using transwell chamber model, we assayed the captivity of invasion andmetastasis of MHCC97-H cells in different groups. We found Bmi-1-siRNAtransfected MHCC97-H cells showed less level of penetrantion than blank andcontrol-siRNA groups(F=186.66,12.746, P <0.05) respectively. Comparedwith blank and control-siRNA groups, the mRNA level of PTEN and E-cadherinwere remarkably increased in the Bmi-1-siRNA transfected MHCC97-H cells.Conclusion: Bmi-1may regulate the invasion and metastasis of HCC.After transfections, the siRNA targeting Bmi-1can successfully knockdown theexpression of Bmi-1of MHCC97-H cell. Silencing Bmi-1could significantlyinhibit the abilities of invasion and metastasis of human hepatocellularcarcinoma cell MHCC97-H in vitro. And Bmi-1may promote the invasion andmetastasis of HCC by regulating the expression of PTEN and E-cadherin. |
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