Tension directs cancer cell migration over fiber alignment through energy minimization.

Cell migration during many fundamental biological processes including metastasis requires cells to traverse tissue with heterogeneous mechanical cues that direct migration as well as determine force and energy requirements for motility. However, the influence of discrete structural and mechanical cues on migration remains challenging to determine as they are often coupled. Here, we decouple the pro-invasive cues of collagen fiber alignment and tension to study their individual impact on migration. When presented with both cues, cells preferentially travel in the axis of tension against fiber alignment. Computational and experimental data show applying tension perpendicular to alignment increases potential energy stored within collagen fibers, lowering requirements for cell-induced matrix deformation and energy usage during migration compared to motility in the direction of fiber alignment. Energy minimization directs migration trajectory, and tension can facilitate migration against fiber alignment. These findings provide a conceptual understanding of bioenergetics during migration through a fibrous matrix.

Retention of E-selectin functionalized liposome fanny packs on Jurkat cells following invasion through collagen.

Circulating immune cells are an appealing candidate to serve as carriers of therapeutic cargo via nanoparticles conjugated to their surface, for several reasons: these cells are highly migratory and can squeeze through small pores of diameter smaller than their resting size; they are easily accessible in the peripheral blood via minimally invasive IV injection of particles, or can be harvested, processed ex vivo, and reintroduced to the body; they are adept at traveling through the circulation with minimal destruction and thus have access to various tissue beds of the body; and immune cells have built-in signal transduction machinery which allows them to actively engage in chemotaxis and home to regions of the tissue containing tumors, invading microorganisms, or injuries in need of wound healing. In this study, we sought to examine and quantify the degree to which nanoscale liposomes, functionalized with E-selectin adhesion receptor, could bind to a model T cell line and remain on the surface of the cells as they migrate through collagen gels of varying density in a transwell cell migration chamber. It is demonstrated that physiological levels of fluid shear stress are necessary to achieve optimal binding of the E-selectin liposomes to the cell surface as expected, and that CD3/CD28 antibody activation of the T cells was not necessary for effective liposome binding. Nanoscale liposomes were successfully conveyed by the migrating cells across a layer of rat tail type 1 collagen gel ranging in composition from 1 to 3 mg/mL. The relative fraction of liposomes carried through the collagen decreased at higher collagen density, likely due to the expected decrease in average pore size, and increased fiber content in the gels. Taken together, these results support the idea that T cells could be an effective cellular carrier of therapeutic molecules either attached to the surface of nanoscale liposomes or encapsulated within their interior.

Link between glucose metabolism and epithelial-to-mesenchymal transition drives triple-negative breast cancer migratory heterogeneity.

Intracellular and environmental cues result in heterogeneous cancer cell populations with different metabolic and migratory behaviors. Although glucose metabolism and epithelial-to-mesenchymal transition have previously been linked, we aim to understand how this relationship fuels cancer cell migration. We show that while glycolysis drives single-cell migration in confining microtracks, fast and slow cells display different migratory sensitivities to glycolysis and oxidative phosphorylation inhibition. Phenotypic sorting of highly and weakly migratory subpopulations (MDA+, MDA-) reveals that more mesenchymal, highly migratory MDA+ preferentially use glycolysis while more epithelial, weakly migratory MDA- utilize mitochondrial respiration. These phenotypes are plastic and MDA+ can be made less glycolytic, mesenchymal, and migratory and MDA- can be made more glycolytic, mesenchymal, and migratory via modulation of glucose metabolism or EMT. These findings reveal an intrinsic link between EMT and glucose metabolism that controls migration. Identifying mechanisms fueling phenotypic heterogeneity is essential to develop targeted metastatic therapeutics.

Highly motile cells are metabolically responsive to collagen density.

Altered tissue mechanics and metabolism have gained significant attention as drivers of tumorigenesis, and mechanoresponsive metabolism has been implicated in migration and metastasis. However, heterogeneity in cell populations makes it difficult to link changes in behavior with metabolism, as individual cell behaviors are not necessarily reflected in population-based measurements. As such, the impact of increased collagen deposition, a tumor-associated collagen signature, on metabolism remains ambiguous. Here, we utilize a wide range of collagen densities to alter migration ability and study the bioenergetics of individual cells over time. Sorting cells based on their level of motility revealed energetics are a function of collagen density only for highly motile cells, not the entire population or cells with low motility. Changes in migration with increasing collagen density were correlated with cellular energetics, where matrix conditions most permissive to migration required less energy usage during movement and migrated more efficiently. These findings reveal a link between matrix mechanics, migratory phenotype, and bioenergetics and suggest that energetic costs are determined by the extracellular matrix and influence cell motility.

Human-derived osteoblast-like cells and pericyte-like cells induce distinct metastatic phenotypes in primary breast cancer cells.

Approximately 70% of advanced breast cancer patients will develop bone metastases, which accounts for ∼90% of cancer-related mortality. Breast cancer circulating tumor cells (CTCs) establish metastatic tumors in the bone after a close interaction with local bone marrow cells including pericytes and osteoblasts, both related to resident mesenchymal stem/stromal cells (BM-MSCs) progenitors. In vitro recapitulation of the critical cellular players of the bone microenvironment and infiltrating CTCs could provide new insights into their cross-talk during the metastatic cascade, helping in the development of novel therapeutic strategies. Human BM-MSCs were isolated and fractionated according to CD146 presence. CD146+ cells were utilized as pericyte-like cells (PLCs) given the high expression of the marker in perivascular cells, while CD146- cells were induced into an osteogenic phenotype generating osteoblast-like cells (OLCs). Transwell migration assays were performed to establish whether primary breast cancer cells (3384T) were attracted to OLC. Furthermore, proliferation of 3384T breast cancer cells was assessed in the presence of PLC- and OLC-derived conditioned media. Additionally, conditioned media cultures as well as transwell co-cultures of each OLCs and PLCs were performed with 3384T breast cancer cells for gene expression interrogation assessing their induced transcriptional changes with an emphasis on metastatic potential. PLC as well as their conditioned media increased motility and invasion potential of 3384T breast cancer cells, while OLC induced a dormant phenotype, downregulating invasiveness markers related with migration and proliferation. Altogether, these results indicate that PLC distinctively drive 3384T cancer cells to an invasive and migratory phenotype, while OLC induce a quiescence state, thus recapitulating the different phases of the in vivo bone metastatic process. These data show that phenotypic responses from metastasizing cancer cells are influenced by neighboring cells at the bone metastatic niche during the establishment of secondary metastatic tumors.