Macrophages unlock progression of breast cancer cells experiencing matrigel-segregation in transplantation models

Abstract

Basement membrane matrix proteins, such as matrigel, are able to improve the efficiency of tumour transplantation. This assay represents the gold standard to measure tumour initiation potential in vivo of a limited number of cancer cells. However, in culture conditions, matrigel directly signals to cancer cells altering their phenotype. We here investigate how matrigel influences the tumour reconstitution dynamics of breast cancer cells in vivo. This is particularly relevant in the setting of limiting dilution assay where cells are transplanted in a relatively high amount of Matrigel. We show that matrigel initially induces a normalized growth of transplanted MMTV-PyMT breast tumours cells. This occurs in the context of a matrigel-segregation effect where cancer cells are transiently isolated from host tissue. We identify macrophages as gatekeepers of the cancer-host cell interaction: depriving transplants from macrophages locked cancer cells in this isolated environment where they fail to form tumours despite retaining their intrinsic tumorigenic potential. This is a decisive proof of concept that cancer cells’ malignant behaviour can be dominated by their microenvironment. Moreover, considering that diverse breast cancer cells are differently subjected to a segregation effect, this needs to be considered when comparing tumour initiation potential of different cancer cells.

Oxidative Stress in Cells with Extra Centrosomes Drives Non-Cell-Autonomous Invasion

“…To establish the relevance of our findings in cancer, we next tested whether CM collected from cells with supernumerary centrosomes could induce invasion in organoid cultures of primary cells from mouse tumors derived from Polyomavirus middle T oncogene (PyMT) ( Ogura et al., 2017 ). We found that CM+DOX was sufficient to increase invasion of tumor organoids after 4 and 7 days’ incubation.…”

“…MMTV-PyMT cell isolation and growth has been previously described ( Ogura et al., 2017 ). Briefly, MMTV-PyMT tumors were isolated, mechanically minced and chemically digested using Liberase and DNase I in HBSS and passed through a 100 μm cell strainer.…”

“…Immunostainings of 3D cultures were performed on partially embedded 3D acini and breast and tumor organoids, both plated on eight-well chambers, according to previous protocols ( Godinho et al., 2014 , Ogura et al., 2017 ). Briefly, the media was removed and the structures were washed with PBS and fixed in 5% of formalin in PBS for 20 min at 37°C.…”

Understanding the Biology of Self-Renewing Macrophages

“…Macrophage number is crucial both for the normal development of the breast and for tissue homeostasis: as mentioned earlier, the absence of macrophages retains the mammary gland in an immature state and also impedes tumor growth. The malignant behavior of cancer cells can be regulated by their microenvironment, which in turn is largely affected by macrophage number and function [ 106 ]. Hence, factors that control the local expansion of mammary gland-associated macrophages have medical potential.…”

Macrophage-Dependent Trafficking and Remodeling of the Basement Membrane-Interstitial Matrix Interface

“…To date, almost all studies have relied on the use of model systems to characterize macrophage interactions with either basement membrane or interstitial matrix barriers (Cougoule et al, 2012; Fleetwood et al, 2014; Gui et al, 2014; Guiet et al, 2011; Guiet et al, 2012; Jevnikar et al, 2012; M. Y. Murray et al, 2013; Ogura, Bridgeman, & Malanchi, 2017; Starnes et al, 2014; Van Goethem et al, 2010; Werb, Bainton, & Jones, 1980). However, given increased appreciation that these constructs cannot recapitulate the more complex structure of the ECM in vivo , and that the composition and mechanical properties of the ECM can each affect cell function (Liu et al, 2015; Previtera & Sengupta, 2015; Wiesner et al, 2014), the utility of these systems for predicting macrophage function in vivo is subject to debate.…”