Effects of Different Tissue Microenvironments on Gene Expression in Breast Cancer Cells
Tissue (brain, bone marrow, or lung) is taken from a donor mouse, minced with a razor, and placed in a dorsal skinfold chamber. After ∼7 days, when the tissue has developed vasculature, tumor spheroids prepared initially from the parental (N202) cell line were grafted on top of the vasculaturized tissue bed. After 21 days, the tumor and tissue were placed in cell culture, allowing tumor cells and cells from the tissue to grow. These were selected using G418 and placed back in tissue culture to increase their numbers. These cells were converted into spheroids and reintroduced onto vascularized tissue in a new dorsal skinfold chamber or sorted on the basis fo GFP fluorescence and analyzed for differential gene expression. This was repeated for up to 4 cycles (P0-P4). Genes were grouped by k-means according to differential gene expression in P1-P4 relative to the parental cell line (P0). These k-means groups were then examined for enrichment of Gene Ontology Biological Process Terms.