Intravital multiphoton imaging reveals multicellular streaming as a crucial component of in vivo cell migration in human breast tumors

Abstract

Metastasis is the main cause of death in breast cancer patients. Cell migration is an essential component of almost every step of the metastatic cascade, especially the early step of invasion inside the primary tumor. In this report, we have used intravital multiphoton microscopy to visualize the different migration patterns of human breast tumor cells in live primary tumors. We used xenograft tumors of MDA-MB-231 cells as well as a low passage xenograft tumor from orthotopically injected patient-derived breast tumor cells. Direct visualization of human tumor cells in vivo shows two patterns of high-speed migration inside primary tumors: a. single cells and b. multicellular streams (i.e., cells following each other in a single file but without cohesive cell junctions). Critically, we found that only streaming and not random migration of single cells was significantly correlated with proximity to vessels, with intravasation and with numbers of elevated circulating tumor cells in the bloodstream. Finally, although the two human tumors were derived from diverse genetic backgrounds, we found that their migratory tumor cells exhibited coordinated gene expression changes that led to the same end-phenotype of enhanced migration involving activating actin polymerization and myosin contraction. Our data are the first direct visualization and assessment of in vivo migration within a live patient-derived breast xenograft tumor.

Signatures of breast cancer metastasis at a glance

“…The resulting profiles were specific to breast cancer cell invasion and dissemination and defined rodent and human invasion signatures (Goswami et al, 2009Patsialou et al, 2013;Patsialou et al, 2012;Roussos et al, 2011b;Wang et al, 2007Wang et al, , 2004. These invasion signatures are enriched in genes that regulate embryonic and tissue development, EMT, cellular movement, DNA replication and repair, apoptosis-evasion and resistance to treatment Patsialou et al, 2013Patsialou et al, , 2012Wang et al, 2003;Wyckoff et al, 2011Wyckoff et al, , 2000. Notably, the disseminating cancer cell subpopulation that gave rise to this signature was more resistant to conventional chemotherapies, such as doxorubicin, etoposide and cisplatin, when compared to the bulk tumor population .…”

“…Notably, the disseminating cancer cell subpopulation that gave rise to this signature was more resistant to conventional chemotherapies, such as doxorubicin, etoposide and cisplatin, when compared to the bulk tumor population . In the discussion below, we focus on the clinically relevant, human invasion signature (HIS) (Patsialou et al, 2013(Patsialou et al, , 2012 and the HIS-derived clinically validated prognostic markers TMEM and Mena Calc .…”

“…One of the reasons for the hampered prognostic and predictive potential of these assays might be the fact that they are based on signatures that have been constructed from whole tumor tissue, which includes all tumor and stromal cells, instead of just the subpopulations of metastasizing tumor cells. To reveal the mechanisms responsible for the metastatic phenotype, gene expression has been performed on disseminating tumor cells, either circulating tumor cells (CTCs) (De Mattos-Arruda et al, 2013), or migratory-disseminating tumor cells isolated from the primary tumor Hernandez et al, 2009;Patsialou et al, 2013Patsialou et al, , 2012Philippar et al, 2008;Roussos et al, 2011a,b,c;Wang et al, 2004Wang et al, , 2005Wang et al, , 2006Wang et al, , 2003Wyckoff et al, 2011Wyckoff et al, , 2000 (see poster). These signatures provide additional insights into the biological processes that are employed during metastasis, such as epithelial-tomesenchymal transition (EMT), invasion and migration, resistance to apoptosis and anoikis, and intravasation.…”

Tumor Cell Invasion Can Be Blocked by Modulators of Collagen Fibril Alignment That Control Assembly of the Extracellular Matrix

“…Particularly in breast tumors, the formation of a dense meshwork of primarily crosslinked collagen fibers has been shown to trigger EMT and cell invasion (35), to facilitate intravasation and distant metastasis formation (36). We, therefore, examined the influence of GS341-treated matrices on human breast cancer cell behavior.…”

Intravital microscopy of cancer: New insights into the spatiotemporal dynamics of the disease

“…Second and Third Harmonic Generation (SHG-THG) imaging have provided insights into tissue texture and organization in relation to cancer development. Correlated imaging of the extracellular matrix (SHG), adipose tissue (THG), stromal and cancer cells has generated a threedimensional map of tissue tracks and barriers that guide melanoma cell invasion (18) and has identified distinct patterns of cell migration in patient-derived xenograft models (2,19). Visualization of angiogenesis has also been achieved using quantum dot imaging of tumor vessels.…”