Human tumors instigate granulin-expressing hematopoietic cells that promote malignancy by activating stromal fibroblasts in mice
Moshe Elkabets, Ann M. Gifford, Christina Scheel, Bjorn Nilsson, Ferenc Reinhardt, Mark-Anthony Bray, Anne E. Carpenter, Karin Jirström, Kristina Magnusson, Benjamin L. Ebert, Fredrik Pontén, Robert A. Weinberg, Sandra S. McAllister
Moshe Elkabets, Ann M. Gifford, Christina Scheel, Bjorn Nilsson, Ferenc Reinhardt, Mark-Anthony Bray, Anne E. Carpenter, Karin Jirström, Kristina Magnusson, Benjamin L. Ebert, Fredrik Pontén, Robert A. Weinberg, Sandra S. McAllister
View: Text | PDF
Research Article

Human tumors instigate granulin-expressing hematopoietic cells that promote malignancy by activating stromal fibroblasts in mice

Abstract

Systemic instigation is a process by which endocrine signals sent from certain tumors (instigators) stimulate BM cells (BMCs), which are mobilized into the circulation and subsequently foster the growth of otherwise indolent carcinoma cells (responders) residing at distant anatomical sites. The identity of the BMCs and their specific contribution or contributions to responder tumor growth have been elusive. Here, we have demonstrated that Sca1+cKit– hematopoietic BMCs of mouse hosts bearing instigating tumors promote the growth of responding tumors that form with a myofibroblast-rich, desmoplastic stroma. Such stroma is almost always observed in malignant human adenocarcinomas and is an indicator of poor prognosis. We then identified granulin (GRN) as the most upregulated gene in instigating Sca1+cKit– BMCs relative to counterpart control cells. The GRN+ BMCs that were recruited to the responding tumors induced resident tissue fibroblasts to express genes that promoted malignant tumor progression; indeed, treatment with recombinant GRN alone was sufficient to promote desmoplastic responding tumor growth. Further, analysis of tumor tissues from a cohort of breast cancer patients revealed that high GRN expression correlated with the most aggressive triple-negative, basal-like tumor subtype and reduced patient survival. Our data suggest that GRN and the unique hematopoietic BMCs that produce it might serve as novel therapeutic targets.

Authors

Moshe Elkabets, Ann M. Gifford, Christina Scheel, Bjorn Nilsson, Ferenc Reinhardt, Mark-Anthony Bray, Anne E. Carpenter, Karin Jirström, Kristina Magnusson, Benjamin L. Ebert, Fredrik Pontén, Robert A. Weinberg, Sandra S. McAllister

×

Figure 4

GRN+ BMCs are selectively recruited to instigated tumors but do not give rise directly to tumor myofibroblasts.

Options: View larger image (or click on image) Download as PowerPoint
GRN+ BMCs are selectively recruited to instigated tumors but do not give...
(A) Representative immunohistochemical staining of responding tumors 14 weeks after injecting admixtures of responder cells with Sca1+cKit– BMCs from control (left) or instigator-bearing mice (right). Tissues were stained for GRN (red) and nuclei were counterstained with hematoxylin (blue). Original magnification, ×630. Graph represents CellProfiler quantification of image area covered by positive GRN staining of indicated responding tumors (n = 3 images per group; P < 0.01). (B) Representative immunohistochemical staining of responding tumors 12 weeks after injecting responder cells contralaterally to either control (left) or instigating tumor cells (right). Images show GRN staining (red) and nuclei counterstaining with hematoxylin (blue). Scale bar: 50 μm. Graph represents CellProfiler quantification of image area covered by positive GRN staining of indicated responding tumors (n = 5 images per group; P < 0.01). (C) Top: merged immunofluorescent image representative of responding tumors at 14 weeks following admixture with Sca1+cKit– BMCs from instigator-bearing mice. Bottom: merged immunofluorescent image representative of responding tumors that had grown for 4 weeks contralaterally to BPLER instigating tumors. Tumors were stained for Sca1 (green) and GRN (red) and nuclei stained with DAPI (blue). Yellow indicates that Sca1+ cells also express GRN. Scale bar: 25 μm. (D–F) Merged immunofluorescent images of responding tumors that had grown for 12 weeks contralaterally to BPLER instigating tumors. Tumors were stained for GRN (red) and αSMA (green); nuclei were stained with DAPI (blue). Scale bars: 100 μm (D); 25 μm (E). F is a magnification of cells shown in E. (G) Graph representing concentration of GRN in plasma from instigator-bearing mice (red), noninstigator-bearing mice (blue), and tumor-free mice (white) (n = 3–5 per group; **P < 0.01, *P < 0.05). Data are expressed as mean ± SEM.