Poster abstracts

Poster number 72 submitted by Julie Wallace

Microarray Analysis of the Mammary Gland Microenvironment in Conditional Pten Mice

Julie A. Wallace (Comprehensive Cancer Center, OSU), Anthony Trimboli, Carmen Z. Stone, Gustavo Leone (Comprehensive Cancer Center, OSU)

Abstract:

Pten is a well known tumor suppressor that has been shown to negatively regulate phosphorylation of the cell survival kinase Akt. Previous work in our laboratory using conditional mouse knockouts has shown that specific deletion of Pten in fibroblasts results in higher tumor incidence and tumor burden in the well characterized ErbB2 breast cancer model. Gene expression analysis of Pten null fibroblasts isolated from mammary glands revealed increased expression of many genes reportedly involved in inflammation and wound healing. Consistently, an increase in the recruitment of F4/80+ macrophages in these mammary glands was also observed. We hypothesized that genetic manipulation of Pten specifically in fibroblasts would also lead to gene expression changes in the various surrounding cell compartments, including not only macrophages but also epithelial and endothelial cells, irrespective of the presence of oncogene. Pten deletion in fibroblasts was achieved using a conditional Pten allele and Cre recombinase under the Fsp1 promoter (fibroblast specific protein promoter 1). Mammary glands from these animals were harvested around 9 weeks, and four different cell types were extracted. RNA was extracted from all samples and submitted for microarray using exon chips. FACS analysis showed between 90-95% pure populations of sorted macrophages and endothelial cells. Quantitative real time PCR using expression markers specific for each individual cell type further confirmed the purity of our isolated cells. Initial results indicate high quality data with four distinct expression sets corresponding to each different cell compartment. A bioinformatics approach is being utilized to understand gene co-expression networks with the ultimate goal of exploring the system-level functionality of genes. Understanding the signaling between a tumor and its microenvironment may have important implications in cancer therapeutics.

Keywords: Pten, Microenvironment, Microarray