1. Compressive stress suppresses proliferation of human epithelium
Ashley Bonnoitt1
, Kenneth Ho1
, Allen Liu1,2
1
Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan
2
Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan
During unrestricted tumor growth, compressive mechanical pressure is exerted onto non-
tumorous adjacent epithelium. The subsequent signal transduction pathway in healthy epithelial
cells surrounding the tumor remains poorly understood. We investigated the
mechanotransduction pathway that controls transcriptional regulation of cell fate via conversion
of mechanical properties of the microenvironment into biochemical signals. We directly applied
mechanical compression over varied timescales on human epithelial (MCF 10A) cell
monolayers seeded on a transwell via an agarose cushion and plastic cap filled with different
weights. We immunostained Ki67, a marker for proliferation, and YAP, a proliferation activator
via the Hippo pathway. After imaging by confocal microscopy, we discerned a negative
correlation between compressional stress and YAP or Ki67 positive cells, insinuating decreased
proliferation with compression. To investigate the progression of different cellular responses we
conducted Western blots at varying timescales. This method permitted us to identify the
expression level of proteins p27, cleaved caspase 3, and PI; a proliferation inhibitor, marker for
apoptosis, and necrosis indicator, respectively. While still preliminary in nature, our methods
and findings set the basis for continued work to understand the specifics behind cellular
responses to compressive stress. With applications to tumor growth and metastasis, future
experiments could look into a cell’s elastic volume response to mechanical compression. Other
possible avenues include investigating any differences in cellular response to compressional
stress when using cancer cells or multicellular spheroids rather than epithelial monolayers.