Human tumors instigate granulin-expressing hematopoietic cells that promote malignancy by activating stromal fibroblasts in mice
Moshe Elkabets, … , Robert A. Weinberg, Sandra S. McAllister
Moshe Elkabets, … , Robert A. Weinberg, Sandra S. McAllister
Published January 25, 2011
Citation Information: J Clin Invest. 2011;121(2):784-799. https://doi.org/10.1172/JCI43757.
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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

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Figure 1

Systemic instigation of responding tumor growth and stromal desmoplasia.

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Systemic instigation of responding tumor growth and stromal desmoplasia....
(A) Systemic instigation injection scheme. HMLER-HR transformed cells (responders) are injected subcutaneously into 1 flank of host mice. The opposite flank is injected with either a Matrigel control or aggressively growing tumor cell lines (instigators or noninstigators). (B) Growth kinetics of instigating and responding tumors. Of the responder cell injections, 1 of 5 formed tumors opposite Matrigel, 4 of 4 formed growing tumors opposite instigating BPLER tumors, and 0 of 5 formed tumors opposite noninstigating PC3 tumors. (C) Histopathology of resulting BPLER and HMLER-HR tumors 90 days after injection. Top panel shows αSMA staining of myofibroblasts and pericytes (brown) and hematoxylin counterstaining of nuclei (blue). Bottom panel shows Masson’s trichrome staining for collagen (blue) and nuclei counterstaining (dark pink). Scale bar: 100 μm. (D) Staining for the SV40 LgT (brown) to identify tumor cells in the resulting tumor tissues. Scale bar: 100 μm. (E and F) CellProfiler quantification of area occupied by αSMA+ staining (E) and number of LgT+ cells (F) in images of resulting tumor tissues under indicated conditions. An average of 10 images of instigating tumors and the contralateral responding tumors (Resp opp instigator) and 5 images of the responding tumor recovered opposite Matrigel (Resp opp Matrigel) were used for quantification. Data are expressed as mean ± SEM.