Aim: To demonstrate the gene expression profiles mediated by hepatitis B virus X protein (HBx), we characterized the molecular features of pathogenesis associated with HBx in a human liver cell model.Methods: We examined gene expression profiles in L-O2-X cells, an engineered L-O2 cell line that constitutively expresses HBx, relative to L-O2 cells using an Agilent 22 K human 70-mer oligonucleotide microarray representing more than 21,329 unique, well-characterized Homo sapiens genes, Weste blot analysis and RNA interference (RNAi) targeting HBx mRNA validated the overexpression of proliferating cell nuclear antigen (PCNA) and Bcl-2 in L-O2-X cells. Meanwhile, the BrdU incorporation assay was used to test cell proliferation mediated by upregulated cyclooxygenase-2 (COX-2).Results: The microarray showed that the expression levels of 152 genes were remarkably altered; 82 of the genes were upregulated and 70 genes were downregulated in L-O2-X cells. The altered genes were associated with signal transduction pathways, cell cycle, metastasis, transcriptional regulation, immune response, metabolism, and other processes. PCNA and Bcl-2 were upregulated in L-O2-X cells. Furthermore, we found that COX-2 upregulation in L-O2-X cells enhanced proliferation using the BrdU incorporation assay, whereas indomethacin (an inhibitor of COX-2) abolished the promotion.Conclusion: Our findings provide new evidence that HBx is able to regulate many genes that may be involved in the car-cinogenesis. These regulated genes mediated by HBx may serve as molecular targets for the prevention and treatment of hepatocellular carcinoma.