ABSTRACT: Using a multiorgan metastasis model of human NSCLC cells (ACC-LC319/bone2) in NK cell-depleted SCID mice, we attempted to identify genes involved in the organ-selective nature of lung cancer-metastasis process, especially bone metastasis. Genome-wide gene expression profile of 15 metastatic lesions from three organs (bone, lung and liver) in this mouse model revealed lot of genes that seemed to reflect the organ specificity of metastatic cells. Among bone-specifically-expressed genes, dozen of genes involved in cell adhesion, cytoskeleton/cell motility, extracellular matrix remodeling, and cell-cell signaling. The upregulation of 11 genes, some of them were either previously reported to be involved in metastatic characteristics, were confirmed by quantitative RT-PCR. The high ability for bone metastasis human lung adenocarcinoma cell line ACC-LC319/bone2 was established in our laboratory from the parental cell line ACC-LC319 (a kind gift from Dr T. Takahashi, Nagoya University, Nagoya, Japan). ACC-LC319 cells with low capacity of bone metastatic ability were selected in vivo for two cycles in bone metastasis mouse models. After two cycles of selection, the derivative cell line designated as ACC-LC319/bone2 showed increased bone metastatic ability compared to parental cell line (Otsuka S., Oncol Res 2009). In this multiorgan metastasis model, SCID mice were depleted NK cells, and two days later, these mice were intravenously injected 1x10^6 cells. The mice were followed up for clinical symptoms and signs of metastases, and were sacrificed on day 34 after tumor inoculation. Metastastic tissues in lung, liver and bone were collected and snap frozen in liquid nitrogen then keep at -80C until cryosection. Laser microbeam microdissection was used to capture pure population of cancer cells in each organ as well as mouse normal tissues in corresponding organ (i.e. the surrounding normal tissues with no microscopic metastasis). Totally, there were 19 samples, including one sample for metastases in each organ (bone, lung and liver) in five mice (i.e., 15 samples); one for each normal mouse tissue (i.e.,three samples); and one for the in vitro cell line (ACC-LC319/bone 2). DNA microarray were performed using Agilent platform, and the gene expression profile of metastases in bone were compared with the gene expression profile of metastases in other two organs (lung, liver). Those genes whose expression in mouse normal tissues was above the cut off value were excluded. The expression of genes in the in vitro cells was used as the universal normalization for the in vivo genes expression.
