Mouse mammary tumor-initiating cells

Using a syngeneic p53 null mouse mammary gland tumor model that closely mimics human breast cancer, we have identified by limiting dilution transplantation as well as in vitro mammosphere and clonogenic assays a Lin-CD29HighCD24High subpopulation of tumor-initiating cells. Differentially expressed genes in the Lin-CD29HighCD24High mouse mammary gland tumor-initiating cell population include those involved in DNA damage response and repair, as well as genes involved in epigenetic regulation previously shown to be critical for stem cell self-renewal. Keywords: tumor-initiating cells The cells were labeled (for FACS sorting) with CD29 and CD24 antibodies, and 4 subpopulations were collected (CD29HighCD24High, CD29HighCD24Low,CD29LowCD24High, and CD29LowCD24Low) to do either in vivo transplantation or to isolate RNA from each of them for array to correlate the in vivo data. 12 samples (RNA of 4 subpopulations based on expression of CD29 and CD24 for each tumor of 3) were included in the identification of differentially expressed genes of tumor-initiating cells. 5 samples (RNA of subpopulations based on expression of CD29 and CD24 of normal mammary epithelial cells ) were included in the normal group analysis. Reference RNA was used to normalize all samples.