Effect of ectopic expression of sFRP1 on MDA-MB-231 human breast cancer cells in vitro and in vivo as xenograft

RNA was isolated from ectopically sFRP1-expressing MDA-MB-231 cells and control MDA-MB-231 cells and as well from tumor lysates arising from these cells as nude mouse xenograft. Gene expression profiles for these samples were investigated using Affymetrix arrays. MDA-MB-231 human breast cancer cells were stably transfected with human sFRP1 encoding vector or empty vector as control. After the selection with antibiotics, three clones of MDA-MB-231/sFRP1 and three clones of MDA-MB-231/control were selected. These six clones were cultured individually in DMEM 10% FCS with 1mg/ml G-418. When cells reached 70-80% confluence, RNA was isolated from the cells. In parallel, the three clones of MDA-MB-231/sFRP1 and the three clones of MDA-MB-231/control were pooled respectively. One million of cells from each pool were suspended in 100ul PBS and injected to fat pads of female balb/c nude mice (6 mice were injected with MDA-MB-231/sFRP1 and 5 mice were injected with MDA-MB-231/control) to do a xenograft experiment. A few - several weeks after, mice were sacrificed when tumor reached a certain size, tumors were taken and RNA was isolated using trizol reagent.