The goal of the present study is to unveil the gene expression profile specific to the biological processes of human breast epithelial cell invasion and migration using an MCF10A model genetically engineered to constitutively activate the H-ras or N-ras signaling pathway. We previously showed that H-Ras, but not N-Ras, induces MCF10A cell invasion/migration, whereas both H-Ras and N-Ras induce cell proliferation and phenotypic transformation. Thus, these cell lines provide an experimental system to separate the gene expression profile associated with cell invasion apart from cell proliferation/transformation. Analysis of whole human genome microarray revealed that 412 genes were differentially expressed among MCF10A, N-Ras MCF10A, and H-Ras MCF10A cells and hierarchical clustering separated 412 genes into four clusters. We then tested whether S100A8 and S100A9, two of the genes which are most highly up-regulated in an H-Ras -specific manner, play a causative role for H-Ras -mediated MCF10A cell invasion and migration. Importantly, small interfering RNA -mediated knockdown of S100A8/A9 expression significantly reduced H-Ras -induced invasion/ migration. Conversely, the induction of S100A8/A9 expression conferred the invasive/migratory phenotype to parental MCF10A cells. Furthermore, we provided evidence of signaling cross-talk between S100A8/A9 and the mitogen-activated protein kinase signaling pathways essential for H-Ras -mediated cell invasion and migration. Taken together, this study revealed S100A8/A9 genes as candidate markers for metastatic potential of breast epithelial cells. Our gene profile data provide useful information which may lead to the identification of additional potential targets for the prognosis and/or therapy of metastatic breast cancer. (Mol Cancer Res 2008;6(10):1544 -53)

Abstract. Dendrobium nobile is widely used as an analgesic, an antipyretic, and a tonic to nourish the stomach in traditional medicine. Mounting evidence suggests an antitumor activity of denbinobin, a major phenanthrene isolated from stems of Dendrobium nobile. The present study aimed to investigate the inhibitory effect of denbinobin on the invasive ability of human cancer cells. The cytotoxicity of denbonobin was examined in several human cancer cell lines including SK-Hep-1 hepatocarcinoma cells, SNU-484 gastric cancer cells, and HeLa cervix cancer cells. Because SNU-484 cells showed the lowest IC 50 value, we examined the effect of denbinobin on the invasive ability of SNU-484 cells. The present study revealed, for the first time, that denbinobin inhibits the invasive phenotype of SNU-484 human gastric cancer cells in a dose-dependent manner. Expressions of matrix metalloproteinase (MMP)-2 and MMP-9 were significantly decreased by denbinobin, suggesting that MMP-2/-9 may be responsible for the antiinvasive activity of denbinobin. We also provide evidence that denbinobin induces apoptosis through down-regulation of Bcl-2 and an up-regulation of Bax. Taken together, this study demonstrates that denbinobin inhibits invasion and induces apoptosis in highly invasive SNU-484 human gastric cancer cells. Given that gastric cancer has been estimated to be one of the most common causes of cancer-related death among Asians and the major cause of death from gastric cancer is the metastatic spread of the disease, our findings may provide useful information regarding the application of denbinobin as a chemopreventive agent that could prevent or alleviate metastatic gastric cancer.