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1. Integrin β1 orchestrates the abnormal cell-matrix attachment and invasive behaviour of E-cadherin dysfunctional cells

   https://doi.org/10.1007/s10120-021-01239-9  

   Figueiredo, Joana ; Ferreira, Rui M. ; Xu, Han ; Gonçalves, Margarida ; Barros-Carvalho, André ; Cravo, Janine ; Maia, André F. ; Carneiro, Patrícia ; Figueiredo, Céu ; Smith, Michael L. ; et al ( September 2021 , Gastric Cancer)

   Tumour progression relies on the ability of cancer cells to penetrate and invade neighbouring tissues. E-cadherin loss is associated with increased cell invasion in gastric carcinoma, and germline mutations of the E-cadherin gene are causative of hereditary diffuse gastric cancer. Although E-cadherin dysfunction impacts cell–cell adhesion, cell dissemination also requires an imbalance of adhesion to the extracellular matrix (ECM).

   To identify ECM components and receptors relevant for adhesion of E-cadherin dysfunctional cells, we implemented a novel ECM microarray platform coupled with molecular interaction networks. The functional role of putative candidates was determined by combining micropattern traction microscopy, protein modulation and in vivo approaches, as well as transcriptomic data of 262 gastric carcinoma samples, retrieved from the cancer genome atlas (TCGA).

   Here, we show that E-cadherin mutations induce an abnormal interplay of cells with specific components of the ECM, which encompasses increased traction forces and Integrin β1 activation. Integrin β1 synergizes with E-cadherin dysfunction, promoting cell scattering and invasion. The significance of the E-cadherin-Integrin β1 crosstalk was validated inDrosophilamodels and found to be consistent with evidence from human gastric carcinomas, where increased tumour grade and poor survival are associated with low E-cadherin and high Integrin β1 levels.

   Integrin β1 is a key mediator of invasion in carcinomas with E-cadherin impairment and should be regarded as a biomarker of poor prognosis in gastric cancer.

    

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2. Effect of correlation between traction forces on tensional homeostasis in clusters of endothelial cells and fibroblasts

   https://doi.org/https://doi.org/10.1016/j.jbiomech.2019.109588  

   Li, J ; Barbone, PE ; Smith, ML ; Stamenovic, D ( January 2020 , Journal of biomechanics)

   The ability of cells to maintain a constant level of cytoskeletal tension in response to external and internal disturbances is referred to as tensional homeostasis. It is essential for the normal physiological function of cells and tissues, and for protection against disease progression, including atherosclerosis and cancer. In previous studies, we defined tensional homeostasis as the ability of cells to maintain a consistent level of cytoskeletal tension with low temporal fluctuations. In those studies, we measured temporal fluctuations of cell-substrate traction forces in clusters of endothelial cells and of fibroblasts. We observed those temporal fluctuations to decrease with increasing cluster size in endothelial cells, but not in fibroblasts. We quantified temporal fluctuation, and thus homeostasis, through the coefficient of variation (CV) of the traction field; the lower the value of CV, the closer the cell is to the state of tensional homeostasis. This metric depends on correlation between individual traction forces. In this study, we analyzed the contribution of correlation between traction forces on traction field CV in clusters of endothelial cells and fibroblasts using experimental data that we had obtained previously. Results of our analysis showed that positive correlation between traction forces was detrimental to homeostasis, and that it was cell type-dependent. 

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3. Engineered Fibrillar Fibronectin Networks as Three‐Dimensional Tissue Scaffolds

   https://doi.org/10.1002/adma.201904580  

   Jordahl, Stacy ; Solorio, Luis ; Neale, Dylan B. ; McDermott, Sean ; Jordahl, Jacob H. ; Fox, Alexandra ; Dunlay, Christopher ; Xiao, Annie ; Brown, Martha ; Wicha, Max ; et al ( September 2019 , Advanced Materials)

   Extracellular matrix (ECM) proteins, and most prominently, fibronectin (Fn), are routinely used in the form of adsorbed pre‐coatings in an attempt to create a cell‐supporting environment in both two‐ and three‐dimensional cell culture systems. However, these protein coatings are typically deposited in a form which is structurally and functionally distinct from the ECM‐constituting fibrillar protein networks naturally deposited by cells. Here, the cell‐free and scalable synthesis of freely suspended and mechanically robust three‐dimensional (3D) networks of fibrillar fibronectin (fFn) supported by tessellated polymer scaffolds is reported. Hydrodynamically induced Fn fibrillogenesis at the three‐phase contact line between air, an Fn solution, and a tessellated scaffold microstructure yields extended protein networks. Importantly, engineered fFn networks promote cell invasion and proliferation, enable in vitro expansion of primary cancer cells, and induce an epithelial‐to‐mesenchymal transition in cancer cells. Engineered fFn networks support the formation of multicellular cancer structures cells from plural effusions of cancer patients. With further work, engineered fFn networks can have a transformative impact on fundamental cell studies, precision medicine, pharmaceutical testing, and pre‐clinical diagnostics.

    

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4. As the endothelial cell reorients, its tensile forces stabilize

   https://doi.org/https://doi.org/10.1016/j.jbiomech.2020.109770  

   Stamenovic, D ; Krishnan, R ; Smith, ML ( May 2020 , Journal of biomechanics)

   When adherent cells are subjected to uniaxial sinusoidal stretch at frequencies close to physiological, their body and their contractile stress fibers realign nearly perpendicularly to the stretch axis. A common explanation for this phenomenon is that stress fibers reorient along the direction where they are unaffected by the applied cyclic stretch and thus can maintain optimal (homeostatic) tensile force. The ability of cells to achieve tensional homeostasis in response to external disturbances is important for normal physiological functions of cells and tissues and it provides protection against diseases, including cancer and atherosclerosis. However, quantitative experimental data that support the idea that stretch-induced reorientation is associated with tensional homeostasis are lacking. We observed previously that in response to uniaxial cyclic stretch of 10% strain amplitudes, traction forces of single endothelial cells reorient in the direction perpendicular to the stretch axis. Here we carried out a secondary analysis of those data to investigate whether this reorientation of traction forces is associated with tensional homeostasis. Our analysis showed that stretch-induced reorientation of traction forces was accompanied by attenuation of temporal variability of the traction field to the level that was observed in the absence of stretch. These findings represent a quantitative experimental evidence that stretch-induced reorientation of the cell’s traction forces is associated with the cell’s tendency to achieve tensional homeostasis. 

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5. Peptide‐Functionalized Hydrogels Modulate Integrin Expression and Stemness in Adult Human Epidermal Keratinocytes

   https://doi.org/10.1002/adbi.201900022  

   Davis‐Hall, Duncan ; Nguyen, Vy ; D'Ovidio, Tyler J. ; Tsai, Ethan ; Bilousova, Ganna ; Magin, Chelsea M. ( August 2019 , Advanced Biosystems)

   The extracellular matrix (ECM) controls keratinocyte proliferation, migration, and differentiation through β‐integrin signaling. Wound‐healing research requires expanding cells in vitro while maintaining replicative capacity; however, early terminal differentiation under traditional culture conditions limits expansion. Here, a design of experiments approach identifies poly(ethylene glycol)‐based hydrogel formulations with mechanical properties (elastic modulus,E= 20.9 ± 0.56 kPa) and bioactive peptide sequences that mimic the epidermal ECM. These hydrogels enable systematic investigation of the influence of cell‐binding domains from fibronectin (RGDS), laminin (YIGSR), and collagen IV (HepIII) on keratinocyte stemness and β₁integrin expression. Quantification of 14‐day keratin protein expression shows four hydrogels improve stemness compared to standard techniques. Three hydrogels increase β₁integrin expression, demonstrating a positive linear relationship between stemness and β₁integrin expression. Multifactorial statistical analysis predicts an optimal peptide combination ([RGDS] = 0.67 mm, [YIGSR] = 0.13 mm, and [HepIII] = 0.02 mm) for maintaining stemness in vitro. Best‐performing hydrogels exhibit no decrease in Ki‐67‐positive cells compared to standards (15% decrease, day 7 to 14;p< 0.05, Tukey Test). These data demonstrate that precisely designed hydrogel biomaterials direct integrin expression and promote proliferation, improving the regenerative capability of cultured keratinocytes for basic science and translational work.

    

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