Poster abstracts

Poster number 16 submitted by Jeff Anderson

Genetic Analysis of Specialized Tumor Associated Macrophages

Jeff Anderson (Biophysics), Tahera Zabuawala (Molecular Gentetics)

Abstract:
Tumor associated macrophages (TAMs) perform various task that are essential for tumor growth, angiogenesis, metastasis, and tumor invasion. Growth factors, chemokines, cytokines and the extra cellular matrix in the tumor microenvironments signal the TAMs to perform these tasks. The tumor microenvironment is not homogeneous and can be classified into several distinct region: for example, sites of tumor invasion, perivascular regions, hypoxic regions and stromal regions. Each of these regions likely has different cytokines and signaling molecules in their microenvironment, that signal messages to the TAMs. Each of these distinct messages specialize the TAMs to perform a distinct role. The purpose of this project is to isolate and analyze TAMs from distinct tumor regions to gain a better understanding of the mechanism behind the specialized role of these TAMs. As a first step towards this goal, we isolated TAMs from a transgenic mouse expressing a yellow fluorescence protein (YFP) under a macrophage/monocyte promoter using Flow Activated Cell Sorting (FACS). We isolated macrophages from normal mice during the stage when the mammary gland is developing, from mice in the early, premalignant stage of breast cancer, and from mice with late stage metastatic breast cancer. We performed microarray analysis on the RNA from these cells, and analyzed the data to find the genes which were upregulated in TAMs versus developmental macrophages, and in late stage TAMs versus TAMs from the earlier premalignant stage of breast cancer. We next looked within our list of genes upregulated in TAMs for candidate cell surface macrophage markers that could be used to classify TAMs based on there association with one of the distinct tumor microenvironments. We then plan to visualize these candidate markers within the tumor microenvironments using immuno-staining of tumor sections. In preliminary work, CD16 was selected as one potential candidate gene that was upregulated late in tumor development compared to earlier stages. Immunostaining indicated CD16 was expressed on a set of macrophages near blood vessels near the tumors, but not in macrophages located within tumors. Macrophage markers like CD16 that are specific to distinct tumor microenvironments can then be used to isolate these macrophages via FACS.

Keywords: Tumor, Macrophages, Microenvironment