The macrophage colony-stimulating factor 1 response signature in breast carcinoma

Abstract

Purpose: Macrophages play an important role in breast carcinogenesis. The pathways that mediate the macrophage contribution to breast cancer and the heterogeneity that exists within macrophages are incompletely understood. Macrophage colony-stimulating factor 1 (CSF1) is the primary regulator of tissue macrophages. The purpose of this study was to define a novel CSF1 response signature and to evaluate its clinical and biological significance in breast cancer.

Experimental design: We defined the CSF1 response signature by identifying genes overexpressed in tenosynovial giant cell tumor and pigmented villonodular synovitis (tumors composed predominantly of macrophages recruited in response to the overexpression of CSF1) compared with desmoid-type fibromatosis and solitary fibrous tumor. To characterize the CSF1 response signature in breast cancer, we analyzed the expression of CSF1 response signature genes in eight published breast cancer gene expression data sets (n = 982) and did immunohistochemistry and in situ hybridization for CSF1 response genes on a breast cancer tissue microarray (n = 283).

Results: In both the gene microarray and tissue microarray analyses, a consistent subset (17-25%) of breast cancers shows the CSF1 response signature. The signature is associated with higher tumor grade, decreased expression of estrogen receptor, decreased expression of progesterone receptor, and increased TP53 mutations (P < 0.001).

Conclusions: Our data show that the CSF1 response signature is consistently seen in a subset of breast carcinomas and correlates with biological features of the tumor. Our findings provide insight into macrophage biology and may facilitate the development of personalized therapy for patients most likely to benefit from CSF1-targeted treatments.

Figure 1

Unsupervised Hierarchical Clustering of Breast Carcinomas with CSF1 Response Genes in Five Datasets. A, Perreard (n=91). B, GSE1379 (n=60). C, GSE1456 (n=159). D, GSE3494 (n=251), E, NKI (n=295). Within the heatmap, yellow represents high expression, black represents median expression, and blue represents low expression. The red highlighted region of the dendrograms above the heatmaps indicates the cluster of breast cancer cases with the CSF1 response signature in each dataset.

Figure 2

Kaplan Meier Survival Curves for Breast Cancer Cases Stratified by CSF1 Response Signature. A, The survival curves are displayed individually for each of the five datasets. B, The survival curves display data pooled from the five datasets for disease free survival, disease specific survival, and overall survival.

Figure 3

Kaplan Meier Survival Curves for CSF1 Response Signature Subset Analyses. Kaplan Meier survival curves are displayed for breast cancer cases stratified by CSF1 response signature for subsets determined by: A, estrogen receptor status; B, grade; and C, p53 mutation signature.

Figure 4

Coordinate Expression of CSF1 and CSF1 Response Proteins in Breast Cancer. A, Unsupervised hierarchical clustering of 272 breast carcinomas based on tissue microarray staining for CSF1 and five CSF1 response markers (CSF1R, CD163, FCGR3a, FCGR2a, CTSL1). The breast cancer cases are arranged along the x axis above the heatmap, and CSF1 and the CSF1 response markers are arranged along the y axis to the right of the heatmap. The CSF1-E row represents CSF1 epithelial expression and the CSF1-S represents CSF1 stromal expression. The colorbar underlying the dendrogram summarizes the expression levels for all 5 CSF1 response markers and shows red for cases expressing at least 4 CSF1 response markers and green for cases expressing less than 4 CSF1 response markers. B, Example of a breast cancer case with stromal expression of CSF1 (in situ hybridization) and five CSF1 response proteins: CSF1R (in situ hybridization), and CD163, FCGR3a, FCGR2a, CTSL1 (immunohistochemistry). Digital images from all TMA cores can be viewed at http://tma.stanford.edu/tma_portal/CSF1_breast