Antisense overexpression of BMAL2 enhances cell proliferation

To identify genes that are frequently downregulated in hepatocellular carcinoma (HCC), a panel of putative underexpressed genes was first established by an in-house cDNA macroarray method. Two different assays, semi-quantitative RT-PCR combined with Northern analysis and customized cDNA microarray analysis, were used to screen through these genes and the results were compared. Several genes, some with unknown function, were confirmed to be downregulated by both the methods. The effect of a downregulated gene, BMAL2, on cell proliferation was examined. Overexpression of antisense BMAL2 RNA in 293EBNA cells resulted in reduced cell cycle time, increased plating efficiency in soft agar, diminished TNF-alpha-induced increment of CPP32/caspase-3 activity, and a reduced proportion of cells in the G2 phase with a concomitantly increased proportion of cells in the S phase. In conclusion, by combining three different methods, we have obtained a panel of frequently down regulated genes in HCC, including BMAL2. Antisense overexpression of BMAL2 enhances cell proliferation.