skip to main content

This content will become publicly available on December 21, 2023

Title: Micromechanical remodeling of the extracellular matrix by invading tumors: anisotropy and heterogeneity
Altered tissue mechanics is an important signature of invasive solid tumors. While the phenomena have been extensively studied by measuring the bulk rheology of the extracellular matrix (ECM) surrounding tumors, micromechanical remodeling at the cellular scale remains poorly understood. By combining holographic optical tweezers and confocal microscopy on in vitro tumor models, we show that the micromechanics of collagen ECM surrounding an invading tumor demonstrate directional anisotropy, spatial heterogeneity and significant variations in time as tumors invade. To test the cellular mechanisms of ECM micromechanical remodeling, we construct a simple computational model and verify its predictions with experiments. We find that collective force generation of a tumor stiffens the ECM and leads to anisotropic local mechanics such that the extension direction is more rigid than the compression direction. ECM degradation by cell-secreted matrix metalloproteinase softens the ECM, and active traction forces from individual disseminated cells re-stiffen the matrix. Together, these results identify plausible biophysical mechanisms responsible for the remodeled ECM micromechanics surrounding an invading tumor.
; ; ;
Award ID(s):
Publication Date:
Journal Name:
Soft Matter
Page Range or eLocation-ID:
9 to 16
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    Following treatment with androgen receptor (AR) pathway inhibitors, ≈20% of prostate cancer patients progress by shedding their AR‐dependence. These tumors undergo epigenetic reprogramming turning castration‐resistant prostate cancer adenocarcinoma (CRPC‐Adeno) into neuroendocrine prostate cancer (CRPC‐NEPC). No targeted therapies are available for CRPC‐NEPCs, and there are minimal organoid models to discover new therapeutic targets against these aggressive tumors. Here, using a combination of patient tumor proteomics, RNA sequencing, spatial‐omics, and a synthetic hydrogel‐based organoid, putative extracellular matrix (ECM) cues that regulate the phenotypic, transcriptomic, and epigenetic underpinnings of CRPC‐NEPCs are defined. Short‐term culture in tumor‐expressed ECM differentially regulated DNA methylation and mobilized genes in CRPC‐NEPCs. The ECM type distinctly regulates the response to small‐molecule inhibitors of epigenetic targets and Dopamine Receptor D2 (DRD2), the latter being an understudied target in neuroendocrine tumors. In vivo patient‐derived xenograft in immunocompromised mice showed strong anti‐tumor response when treated with a DRD2 inhibitor. Finally, we demonstrate that therapeutic response in CRPC‐NEPCs under drug‐resistant ECM conditions can be overcome by first cellular reprogramming with epigenetic inhibitors, followed by DRD2 treatment. The synthetic organoids suggest the regulatory role of ECM in therapeutic response to targeted therapies in CRPC‐NEPCs and enable the discovery of therapies to overcome resistance.


    Pancreatic ductal adenocarcinoma (PDAC) is among the most lethal of human malignancies. PDAC is characterized by dense fibrous stroma which obstructs drug delivery and plays complex tumor‐promoting roles. Photodynamic therapy (PDT) is a light‐based modality which has been demonstrated to be clinically feasible and effective for tumors of the pancreas. Here, we usein vitroheterocellular 3D co‐culture models in conjunction with imaging, bulk rheology and microrheology to investigate photodegradation of non‐cellular components of PDAC stroma (photodynamic stromal depletion, PSD). By measuring the rheology of extracellular matrix (ECM) before and after PDT we find that softening of ECM is concomitant with increased transport of nanoparticles (NPs). At the same time, as shown by us previously, photodestruction of stromal fibroblasts leads to enhanced tumor response to PDT. Here we specifically evaluate the capability of PSD to enhance RNA nanomedicine delivery, using a NP carrying an inhibitor of miR‐21‐5P, a PDAC oncomiR. We confirm improved delivery of this therapeutic NP after PSD by observation of increased expression of PDCD4, a protein target of miR‐21‐5P. Collectively, these results in 3D tumor models suggest that PSD could be developed to enhance delivery of other cancer therapeutics and improve tumor response to treatment.

  3. Cells in vivo generate mechanical traction on the surrounding 3D extracellular matrix (ECM) and neighboring cells. Such traction and biochemical cues may remodel the matrix, e.g., increase stiffness, which, in turn, influences cell functions and forces. This dynamic reciprocity mediates development and tumorigenesis. Currently, there is no method available to directly quantify single-cell forces and matrix remodeling in 3D. Here, we introduce a method to fulfill this long-standing need. We developed a high-resolution microfabricated sensor that hosts a 3D cell-ECM tissue formed by self-assembly. This sensor measures cell forces and tissue stiffness and can apply mechanical stimulation to the tissue. We measured single and multicellular force dynamics of fibroblasts (3T3), human colon (FET) and lung (A549) cancer cells, and cancer-associated fibroblasts (CAF05) with 1-nN resolution. Single cells show notable force fluctuations in 3D. FET/CAF coculture system, mimicking cancer tumor microenvironment, increased tissue stiffness by three times within 24 hours.
  4. Abstract

    Clinical and animal studies have reported the influence of sex on the incidence and progression of tendinopathy, which results in disparate structural and biomechanical outcomes. However, there remains a paucity in our understanding of the sex‐specific biological mechanisms underlying effective tendon healing. To overcome this hurdle, our group has investigated the impact of sex on tendon regeneration using the super‐healer Murphy Roths Large (MRL/MpJ) mouse strain. We have previously shown that the scarless healing capacity of MRL/MpJ patellar tendons is associated with sexually dimorphic regulation of gene expression for pathways involved in fibrosis, cell migration, adhesion, and extracellular matrix (ECM) remodeling following an acute mid‐substance injury. Thus, we hypothesized that MRL/MpJ scarless tendon healing is mediated by sex‐specific and temporally distinct orchestration of cell–ECM interactions. Accordingly, the present study comparatively evaluated MRL/MpJ tendon cells on two‐dimensional (2D; glass) and scaffold platforms to examine cell behavior under biochemical and topographical cues associated with tendon homeostasis and healing. Female MRL/MpJ cells showed reduced 2D migration and spreading area accompanied by enhanced mechanosensing, ECM alignment, and fibronectin‐mediated cell proliferation compared to male MRL/MpJ cells. Interestingly, female MRL/MpJ cells cultured on isotropic scaffolds showed diminished cell–ECM organization compared to male MRL/MpJ cells. Lastly,more »MRL/MpJ cells elicited enhanced cytoskeletal elongation and alignment, ECM deposition and organization, and connexin 43‐mediated intercellular communication compared to male B6 cells, regardless of culture condition or sex. These results provide insight into the cellular features conserved within the MRL/MpJ phenotype and potential sex‐specific targets for the development of more equitable therapeutics.

    « less
  5. Contact guidance is a powerful topographical cue that induces persistent directional cell migration. Healthy tissue stroma is characterized by a meshwork of wavy extracellular matrix (ECM) fiber bundles, whereas metastasis-prone stroma exhibit less wavy, more linear fibers. The latter topography correlates with poor prognosis, whereas more wavy bundles correlate with benign tumors. We designed nanotopographic ECM-coated substrates that mimic collagen fibril waveforms seen in tumors and healthy tissues to determine how these nanotopographies may regulate cancer cell polarization and migration machineries. Cell polarization and directional migration were inhibited by fibril-like wave substrates above a threshold amplitude. Although polarity signals and actin nucleation factors were required for polarization and migration on low-amplitude wave substrates, they did not localize to cell leading edges. Instead, these factors localized to wave peaks, creating multiple “cryptic leading edges” within cells. On high-amplitude wave substrates, retrograde flow from large cryptic leading edges depolarized stress fibers and focal adhesions and inhibited cell migration. On low-amplitude wave substrates, actomyosin contractility overrode the small cryptic leading edges and drove stress fiber and focal adhesion orientation along the wave axis to mediate directional migration. Cancer cells of different intrinsic contractility depolarized at different wave amplitudes, and cell polarization response tomore »wavy substrates could be tuned by manipulating contractility. We propose that ECM fibril waveforms with sufficiently high amplitude around tumors may serve as “cell polarization barriers,” decreasing directional migration of tumor cells, which could be overcome by up-regulation of tumor cell contractility.

    « less