Biophysical control of invasive tumor cell behavior by extracellular matrix microarchitecture

Abstract

Fibrillar collagen gels, which are used extensively in vitro to study tumor-microenvironment interactions, are composed of a cell-instructive network of interconnected fibers and pores whose organization is sensitive to polymerization conditions such as bulk concentration, pH, and temperature. Using confocal reflectance microscopy and image autocorrelation analysis to quantitatively assess gel microarchitecture, we show that additional polymerization parameters including culture media formulation and gel thickness significantly affect the dimensions and organization of fibers and pores in collagen gels. These findings enabled the development of a three-dimensional culture system in which cell-scale gel microarchitecture was decoupled from bulk gel collagen concentration. Interestingly, morphology and migration characteristics of embedded MDA-MB-231 cells were sensitive to gel microarchitecture independently of collagen gel concentration. Cells adopted a polarized, motile phenotype in gels with larger fibers and pores and a rounded or stellate, less motile phenotype in gels with small fibers and pores regardless of bulk gel density. Conversely, cell proliferation was sensitive to gel concentration but not microarchitecture. These results indicate that cell-scale gel microarchitecture may trump bulk-scale gel density in controlling specific cell behaviors, underscoring the biophysical role of gel microarchitecture in influencing cell behavior.

Inelastic behaviour of collagen networks in cell–matrix interactions and mechanosensation

“…This model enables comparisons with cells on thin collagen matrices supported by an underlying rigid foundation without changing the thickness of the collagen. Variation of collagen thickness may markedly influence the network architecture and organization of collagen fibres in the network [40]. With this model, we found that the degree of collagen fibre alignment, the size of the nascent deformation field and the rate of network deformation by adherent cells was dependent on collagen concentration.…”

Comparison of Picrosirius Red Staining With Second Harmonic Generation Imaging for the Quantification of Clinically Relevant Collagen Fiber Features in Histopathology Samples

“…3 Mechanistically, it is hypothesized that aligned collagen fibers form pathways that facilitate cancer cell migration away from the tumor and toward vasculature during the metastatic process. 3,4 While there is significant research work ongoing on the role of collagen in live, dynamic in vitro and in vivo animal models of a wide array of cancers, [5][6][7][8][9][10] many groups, including ours, are also focused on investigating the potential clinical utility of collagen properties in routinely fixed and processed human tissues. Toward clinical translation, it has already been shown that the detection of TACS in routine histopathological evaluation of breast cancer can serve as an optical biomarker and be predictive of disease recurrence and patient survival.…”

Mechanotransduction of mesenchymal melanoma cell invasion into 3D collagen lattices: Filopod-mediated extension–relaxation cycles and force anisotropy

“…The forces generated by individual cells or cell populations are detected as displacement of co-embedded reference markers, such as beads, followed by mathematical postprocessing [5,9,16,17]. Alternatively, or in addition, ECM fibrils are directly detected by differential interference contrast [18] or 3D confocal reflectance microscopy [19][20][21] to track the kinetics of reversible or irreversible displacement and transport [22,23]. When combined with bright field and/ or fluorescence microscopy, 3D scaffold imaging in fixed or live cultures allows the time-and phase-resolved detection of cellmatrix interaction and cell-imposed ECM alignment during cell migration [16,19,20].…”

“…For fibroblasts embedded in 3D fibrillar collagen, confocal reflectance microscopy has revealed cytoskeletal focalization and actomyosin mediated contractility as the basis of migration and structural remodeling of tissue [6,24,25]. In mesenchymal tumor cells, the mechanotransduction to collagen depends upon integrinmediated adhesion to collagen fibrils [26,27], myosin-II mediated contraction of actin filaments [20,21,24], and intracellular mechanocoupling between adhesion receptors and the actin cytoskeleton by focal adhesion kinase, talin and p130Cas [16]. The main force vector may either result from a single protrusion persisting over extended time periods [26], or multiple protrusions that form and retract to generate a combinatorial net vector of translocation over time [16].…”