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Objective: To study the effect of B cell-specific murine leukemia virus integration site-1 (BMI-1) gene expression inhibited by RNA interference on doxorubicin (Dox) -resistance of hepatocellular carcinoma cells, and to explore its related molecular mechanism.Methods: The Dox-resistant MHCC-97H cell line was established and named as 97H/Dox, while the parental MHCC-97H cell line (named as 97H) was used as the control. The drug-resistance, cell colony-forming capacity and invasive ability were measured by MTT method, cell colony formation assay and in vitro Transwell invasive experiment, respectively. The mRNA and protein levels of tumor-related genes were detected by real-time fluorescent quantitative-PCR (RFQ-PCR) and Western blotting. Then the small interference RNA (siRNA) targeting BMI-1 gene (BMI-1-siRNA) was transfected into 97H/Dox and 97H cells. After BMI-1 gene silencing, the changes of Dox-resistance of 97H/Dox and 97H cells were detected by MTT method, and the change of expressions of tumor-related proteins in 97H cells was detected by Western blotting.Results: The 97H/Dox cell line had a stable multiple-drug resistance, and its colony formation capacity was higher than that of the control cell line 97H (P < 0.05). The levels of BMI-1, ATP-binding cassette superfamily G member 2 (ABCG2) and matrix metalloproteinase-2 (MMP-2) were significantly increased in 97H/Dox cells compared with those in the control 97H cells (all P < 0.05). Knockdown of BMI-1 gene by siRNA significantly increased the sensitivity to Dox in 97H/Dox and 97H cells (both P < 0.05), and resulted in a significant reduction of the expression levels of phospho-Akt (p-Akt), phospho-c-Jun N-terminal kinase (p-JNK) and ABCG2 in 97H cells (all P < 0.05).Conclusion: The upregulation of BMI-1 gene expression may be involved in the acquisition of Dox-resistance in hepatocellular carcinoma 97H cells. Inhibition of BMI-1 expression can enhance the sensitivity to Dox in hepatocellular carcinoma cells. Therefore, interfering the expression of BMI-1 gene may be a potential strategy for enhancing the response to chemotherapy in treatment of hepatocellular carcinoma. DOI:10.3781/j.issn.1000-7431.2015.11.744