Mechanobiological regulation of breast epithelium organization and cell invasion
Lead supervisor: R. Merkel, Co-supervisor: H. Fischer, Junior supervisor: E.Noetzel-Reiss Forschungszentrum Jülich, Institute of Complex Systems-7: Biomechanics
Hypothesis: Force homeostasis and an intact basement membrane (BM) are decisive for epithelial tissue organization.
Graphical summary of project A2. Design of the experimental approaches, work packages and own preliminary data.
Background: The mammary gland consists of multiple spheroidal acini that are separated from the surrounding connective tissue by a basement membrane (BM). The epithelial lining of the acini is subjected to compressive and expansive stresses by contractile myoepithelial cells, the extracellular matrix, and luminal secretions. We have recently characterized the BM protein scaffold as an important mechanical stabilizer for breast acini using a well-established 3D cell culture model and proposed that it acts as a physical barrier for invasive tumor cells 40. Aims: We aim to decipher the mechanobiological processes of epithelial organization in response to BM disruption and mechanical stresses using spheroids derived from human epithelial mammary gland cell lines. ECM stiffness, tissue pressure and shear stress are systematically analyzed as key biophysical stimuli. The focus lies on the characterization of cellular responses that transduce these mechanical cues into morphological cell adaptation. We intend to contribute to a better understanding of mechanobiological key mechanisms that steer epithelial cell behavior during breast gland formation, maintenance and tumor cell invasion. Approach: Breast gland formation and cell invasion are studied in 3D cell cultures of human non-tumorigenic MCF10A and HMT3522-S1 cell linesHYPERLINK "https://meet.rwth-aachen.de/quotes.html" 41,42. The multicellular spheroids show a basoapical polarization with BM formation and defined cell-cell and cell-matrix junctions. Based on our extensive experience in analyzing cellular stress and strain, we will investigate cell force as a novel non-proteolytical mechanism of BM disruption and its implications for cancer Invasion HYPERLINK "https://meet.rwth-aachen.de/quotes.html" 6,43,44. The well-documented influence of tumor-associated ECM stiffening on Invasion is also explored for this cell-force-mediated mechanism. To this end, cellular force microscopy techniques designed in-house are used. The underlying mechanosensitive signaling pathway regulation is characterized on the gene expression level. Furthermore, the impact of tissue pressure and shear stress on epithelial tissue organization is investigated systematically using special devices recently designed by us.