Identification of the p33-regulated Genes that Include Cyclin B1 and Proto- oncogene DEK by Using cDNA Microarray in a Mouse Mammary Epithelial Cell Line NMuMG

The candidate tumor suppressor p33 plays an important role in inducing growth arrest at G0-G1 phase of the cell cycle and/or promoting apoptosis in cancerous cells. p33 is reported to act as a transcriptional cofactor by associating with tumor suppressor p53, HAT, or histone deacetyltransferase, suggesting that p33 is involved in chromatinmediated transcriptional regulation. However, the molecular mechanism of p33-mediated transcriptional regulation is poorly understood. Here we analyzed expression profiles in mouse mammary epithelial cells (NMuMG) by using a cDNA microarray consisting of 2304 mouse cDNAs after inducing transformation with antisense inhibitor of growth 1 (ING1) in retrovirus vector. The subsequent confirmation of the altered expression levels of the selected genes by semiquantitative reverse transcriptionPCR demonstrated that overexpression of the antisense ING1 stimulated expression of 14 genes, which included cyclin B1, 12-O-tetradecanoylphorbol-13-acetate-inducible sequence 11, proto-oncogene DEK, and osteopontin, whereas we have detected transcriptional repression of 5 genes, including TPT1. In addition, adenovirus-mediated overexpression of ING1 in NMuMG cells resulted in down-regulation of cyclin B1, 12-O-tetradecanoylphorbol-13-acetate-inducible sequence 11, DEK, and osteopontin, whereas the levels of TPT1 expression were increased. The further analysis using p53 / SAOS2 cells showed that the p33-induced cyclin B1 down-regulation was p53 dependent. Thus, our cDNA microarray analysis suggested that p33 targets the multiple genes, including proto-oncogene DEK and cyclin B1, at least some of which are regulated in a p53-dependent manner, in the cells undergoing cell growth or apoptosis.