Oriented collagen fibers direct tumor cell intravasation

Abstract

In this work, we constructed a Collagen I-Matrigel composite extracellular matrix (ECM). The composite ECM was used to determine the influence of the local collagen fiber orientation on the collective intravasation ability of tumor cells. We found that the local fiber alignment enhanced cell-ECM interactions. Specifically, metastatic MDA-MB-231 breast cancer cells followed the local fiber alignment direction during the intravasation into rigid Matrigel (∼10 mg/mL protein concentration).M etastasis is a lethal milestone in cancer: Cells escape from the confinement of primary tumor sites (intravasation), invade tissues as well as the lymphatic and vascular systems, and finally colonize (extravasation) distant sites. It has been estimated that less than 1% of tumor cells undergo this process, but metastasis contributes to more than 90% of cancerrelated deaths (1, 2). Metastasis involves both genetic and epigenetic alternation of tumor cells, as well as external biochemical and biophysical microenvironments (3-5). Pathology studies suggest that metastatic tumor cells exhibit highly branched morphologies and distinct aligned registration with aligned extracellular matrix (ECM) during metastatic tumor progression (4, 5).We address three important questions concerning metastasis. (i) Can we build in vitro complex ECM structures with heterogeneously oriented collagen fibers and basement membrane components to mimic the cancer cell intravasation process? (ii) How does aligned collagen influence cell intravasation into/ through the basement membrane before entering vessels? (iii) After cell detachment from the primary tumor site, how does a heterogeneous ECM with a varying degree of local fiber alignment influence cell intravasation and subsequent penetration into the basement membrane during their intravasation process? The major obstacle to addressing these questions is the difficulty in constructing both an in vitro 3D microenvironment to mimic the above process and flexible controls of the environmental parameters, such as fiber orientations in a complex collagen/Matrigel composite, nutrition, oxygen, drug concentrations, etc.In breast cancer metastasis, cancer cells are believed to reorganize and progress through the interstitial ECM matrix, break through the basement membrane, and enter blood vessels or lymphatic capillaries (6-10). Fig. 1C presents a schematic illustration of the intravasation process in metastasis. Tumor-associated collagen signatures (TACS), basically environmentally elevated collagen density and collagen fiber reorganization, are used to stage mammary carcinoma tumor progression levels (6, 11-13). Fig. 1 presents hematoxylin/eosin (H&E)-stained biopsy slices of breast cancer imaged by second harmonic generation (SHG) under a two-photon confocal microscopy (A1R MP; Nikon) (detailed information provided in SI Appendix, SI Text) (6, 14, 15). Fig. 1 A, 1-3 shows the stained human invasive ductal carcinoma tumor at grade I. In the enlarged figures (Fig. 1 A, 2 and 3), the cells have well-defined bord...

Collective forces of tumor spheroids in three-dimensional biopolymer networks

“…The motivation for this extension is that tumor spheroids are able to replicate the main structural and functional properties of solid tumors 10 , including the individual and collective invasion into the surrounding matrix 11 . In particular, it has been hypothesized that the collective traction force of a whole tumor may alter the mechanics of the extracellular matrix and facilitate invasion by aligning collagen fibers radially away from the tumor [12][13][14] . However, current 3D finite element force reconstruction methods for single cells, especially in a non-linear material such as collagen, are computationally too slow for analyzing large (∼0.5 mm) tumor spheroids.…”

Crosshatch nanofiber networks of tunable interfiber spacing induce plasticity in cell migration and cytoskeletal response

“…This seemingly straightforward question has been difficult to resolve because of challenges in imaging deep inside the body over long periods (3,4) and recapitulation of structures in vitro (5). Thus, it is not uncommon to find illustrations of fibrous ECM interfacing with tumors depicting the existence of both aligned fibers and nonaligned configurations of varying pore sizes and lengths that are able to support persistent migration (2,(6)(7)(8)(9)(10)(11)(12).…”

EFA6B regulates a stop signal for collective invasion in breast cancer

“…Contractility is reflected by the formation of linearized bundles of collagen extending from filopodia of invasive EFA6B KO cells. These collagen bundles were shown to form tracts that facilitate tumor cells migration 21,45 . Cell contractility stiffens the matrix, and thus stimulates the formation of invodopodia and secretion of MMPs 46 .…”