Hemodynamic shear stress influences the epithelial/mesenchymal phenotype of suspended tumor cells. (a) Representative images of tumor cell morphology after shear stress treatment are shown. Suspended MDA-MB-468 cells treated under different shear stresses were cultured on collagen-coated glass. Cell images were taken at the indicated time points after removing nonadhered cells. Scale bar, 100 μm. (b and c) Fluid shear stress promotes elongated morphology and spreading of circulating tumor cells (CTCs). The aspect ratio (b) and spreading area (c) of the treated tumor cells in (a) were quantified (n > 92); n = 3 independent experiments. (d) Fluid shear stress influences the expressions of mesenchymal/epithelial genes in CTCs. The expressions of epithelial marker (E-cadherin) and mesenchymal markers (Twist, fibronectin, and vimentin) in surviving tumor cells were measured by quantitative RT-PCR. E-cadherin and Twist were analyzed by Western blotting; n = 2 and 3 independent experiments for the top and bottom panels, respectively. The statistics were conducted using ANOVA with the post hoc Bonferroni test in (b) and (c) and Tukey test in (d). ∗p < 0.05; ∗∗p < 0.01; ∗∗∗p < 0.001. To see this figure in color, go online.