Expression data in mouse primary mammary tumors

Many preclinical therapy studies have focused on a small number of well-described mouse allograft or human xenograft models that poorly represent the heterogeneity of human disease. Here we have assembled a panel of mouse mammary cell lines that metastasize in syngeneic mouse hosts and we have assessed gene expression programs in the untreated primary tumors with the goal of generating information that may be useful to the identification of biomarkers that predict response to therapeutic intervention. We used microarrays to assess global gene expression programs in primary tumors from 12 metastatic mouse mammary tumor models transplanted orthotopically into syngeneic, fully immunocompetent mouse hosts. The 12 tumor models used here are based on published cell lines that had been established from either spontaneous mammary tumors or from mammary tumors arising in genetically engineered mouse models. All cell lines were previously described to be metastatic. Cells were surgically implanted in the #4 mammary fat pads of syngeneic mice and primary tumors were harvested when they reached 0.5-1.0 cm diameter and snap-frozen for later RNA extraction. 4 independent tumors were collected for each of the 12 models.