Abstract: The aims of this work are to have the bioinformatics analysis of hsa-miR-3661 regulated by p53，which was found in doxorubicin（Dox）inducing the DNA damages of hepatoma cell HepG2 in previous experiment，and to verify its function by molecular biological experiment，providing theoretical basis for the regulating mechanism of miR-3661 in hepatoma cells. After acquiring the structure and sequence information of miR-3661，we predicted the target genes and used DAVID to do the functional enrichment analysis of miRNA target gene. We then analyzed the binding sites of p53 and miR-3661，and built the regulatory network by the interaction among genes. Finally，multiplication experiment verified the functions of miR-3661 in restraining tumor. The results showed that miR-3661 sequence was conserved，and the promoter region existed in the binding site of p53，suggesting that there was direct regulation between p53 and hsa-miR-3661. We predicted that there were 1009 target genes，and 369 genes of them significantly enriched in the biological procedure related to tumor，such as cell cycle regulation，proliferation，apoptosis and so on（P < 0.05），mainly involved in cancer pathway，MAPK signaling pathway，ErbB signaling pathway（P < 0.05）. Using the interactions of 2830 groups of genes，we constructed the regulatory network among p53，hsa-miR-3661 and target genes，and analyzed key target gene participating in several tumorous biological process from the perspective of system biology. It was confirmed in the experiment that the overexpression of miR-3661 significantly inhibited the proliferation of hepatoma cell HepG2 （P-value= 0.00146）. In conclusion，miR-3661 is directly regulated by p53 and its target genes significantly enrich in various biological processes and signal pathways related to tumor. Moreover，the overexpression of miR-3661 significantly inhibits the proliferation of hepatoma cell.

Key words: hepatocellular carcinoma, microRNAs, bioinformatics, doxorubicin