Cellular shear stiffness reflects progression of arsenic-induced transformation during G1

Cancer cells consistently exhibit decreased stiffness, however the onset and progression of this change has not been characterized. To study the development of cell stiffness changes we evaluated the shear stiffness of populations of cells during transformation to a carcinogenic state. Bronchial epithelial cells were exposed to sodium arsenite to initiate early stages of transformation.

Exposed cells were cultured in soft agar to further transformation and select for clonal populations exhibiting anchorage independent growth. Shear stiffness of various cell populations in G1 was assessed using a novel non-invasive assay that applies shear stress with fluid flow and evaluates nano-scale deformation using quantitative phase imaging (QPI).

Arsenic treated cells exhibited reduced stiffness relative to control cells, while arsenic clonal lines, selected by growth in soft agar, were found to have reduced stiffness relative to control clonal lines, which were cultured in soft agar but did not receive arsenic treatment. The relative standard deviation of the stiffness of Arsenic clones was reduced compared to control clones, as well as to the arsenic exposed cell population.

Cell stiffness at the population level exhibits potential to be a novel and sensitive framework for identifying the development of cancerous cells.