Tissue mechanics in stem cell fate, development, and cancer.

Cells in tissues experience a plethora of forces that regulate their fate and modulate development and homeostasis. Cells sense mechanical cues through localized mechanoreceptors or by influencing cytoskeletal or plasma membrane organization. Cells translate force and modulate their behavior through a process termed mechanotransduction. Cells tune their tension upon exposure to chronic force by engaging cellular machinery that modulates actin tension, which in turn stimulates matrix remodeling and stiffening and alters cell-cell adhesions until cells achieve a state of tensional homeostasis. Loss of tensional homeostasis can be induced through oncogene activity and/or tissue fibrosis, accompanies tumor progression, and is associated with increased cancer risk. The mechanical stresses that develop in tumors can also foster the mesenchymal-like transdifferentiation of cells to induce a stem-like phenotype that contributes to their aggression, metastatic dissemination, and treatment resistance. Thus, strategies that ameliorate tumor mechanics may comprise an effective strategy to prevent aggressive tumor behavior.

Adhesion-mediated mechanosignaling forces mitohormesis.

Mitochondria control eukaryotic cell fate by producing the energy needed to support life and the signals required to execute programed cell death. The biochemical milieu is known to affect mitochondrial function and contribute to the dysfunctional mitochondrial phenotypes implicated in cancer and the morbidities of aging. However, the physical characteristics of the extracellular matrix are also altered in cancerous and aging tissues. Here, we demonstrate that cells sense the physical properties of the extracellular matrix and activate a mitochondrial stress response that adaptively tunes mitochondrial function via solute carrier family 9 member A1-dependent ion exchange and heat shock factor 1-dependent transcription. Overall, our data indicate that adhesion-mediated mechanosignaling may play an unappreciated role in the altered mitochondrial functions observed in aging and cancer.

Mechanical Control of Epithelial-to-Mesenchymal Transitions in Development and Cancer.

Mechanical force modulates development, influences tissue homeostasis, and contributes to disease. Forces sculpt tissue-level behaviors and direct cell fate by engaging mechanoreceptors and by altering organization of the cytoskeleton and actomyosin contractility to stimulate mechanotransduction mechanisms that alter transcription. Nevertheless, how force specifically leverages mechanotransduction pathways to control transcriptional regulation of cell fate remains unclear. Here we review recent findings specifically in the context of epithelial-to-mesenchymal transitions that have revealed conserved mechanisms whereby extracellular force, mediated through cell-extracellular matrix and cell-cell junctional complexes, induces transcriptional reprogramming to alter cell and tissue fate. We focus on the interplay between tissue mechanics and the epithelial-to-mesenchymal transitions that occur during embryonic development and cancer malignancy. We describe the adhesion-linked cellular machinery that mediates mechano-transduction and elaborate on how these force-linked networks stimulate key transcriptional programs that induce an epithelial-to-mesenchymal phenotypic transition, thereby providing an overview of how mechanical signals can be translated into a change in cell fate.