Comparative in situ gene expression profile of starry-sky tumor-associated macrophages and germinal centre macrophages

ABSTRACT: Cells undergoing apoptosis are known to modulate their tissue microenvironments. By acting on phagocytes, notably macrophages, apoptotic cells inhibit immunological and inflammatory responses and promote trophic signaling pathways. Paradoxically because of their potential to cause death of tumor cells and thereby militate against malignant disease progression, both apoptosis and tumor-associated macrophages (TAM) are often associated with poor prognosis in cancer. In order to better understand the influence of tumor cell apoptosis and in particular its effect on TAM, we investigated global gene expression signatures of undisturbed TAM engaged in engulfment of apoptotic tumor cells. We studied a xenograft model of an aggressive ‘starry-sky’ non-Hodgkin’s lymphoma, Burkitt’s lymphoma (BL), in which apoptotic tumor cells are common and frequently observed in association with the starry-sky TAM (SS-TAM, so called because they appear histologically as ‘stars’ in a ‘sky’ of tumor cells) that accumulate in these tumors. We used a BL cell line (BL2) whose cells phenotypically resemble the tumor biopsy cells from which the line was derived including the capacity to undergo apoptosis constitutively. BL xenografts in SCID mice closely recapitulated the starry-sky histological picture of the human lymphoma. Due to the high sensitivity of macrophages to their environments, we adopted laser-capture microdissection of individual SS-TAM in BL xenografts in order to obtain unbiased in situ transcriptional profiles of these cells, which we compared specifically with those of similarly-captured macrophages, the tingible-body macrophages from normal germinal centers (GCM). The rationale for this comparison was based upon BL being a germinal center malignancy and tingible-body macrophages being regarded as normal equivalents of SS-TAM. Gene expression profiles of SS-TAM from BL2 xenograft tumors were compared to splenic GCM profiles. Three mice from each group were analysed. RNA was isolated from 1000 captured macrophages from each mouse and global gene expression signatures were obtained using Affymetrix Mouse Gene 1.0 GeneChip arrays.

ORGANISM(S): Mus musculus

SUBMITTER: Christopher Gregory 

PROVIDER: E-GEOD-64366 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress