Figure 4.

Suspended tumor cells surviving fluid shear stress exhibit reduced F-actin assembly and cell stiffness. (a) Immunofluorescence imaging and immunoblotting of F-actin in breast cancer cells after shear stress treatment are shown. MDA-MB-468 cells were treated under 0 and 20 dyne/cm² shear stress for 12 h and then plated on glass for 10 h, after which F-actin was stained and the immunoblotting of G-actin (G) and F-actin (F) was conducted. The level of total actin was used as a control. The value represents the F-actin/G-actin ratio; n = 2 independent experiments. The nucleus was counterstained with 4′,6-diamidino-2-phenylindole (DAPI). Scale bars, 50 μm. (b) Surviving tumor cells show much lower F-actin assembly. F-actin in the top panel of (a) was quantified (n > 100); n = 3 independent experiments. (c) Typical force-indentation curves of breast cancer cells after shear stress treatment measured by atomic force microscopy are shown. (d) Breast cancer cells surviving hemodynamic shear stress exhibit much lower stiffness. MDA-MB-468 cells after shear stress treatment were plated on glass for 10 h, after which cell stiffness was measured. At least 150 cells were measured for each condition; n = 3 independent experiments. The statistics were conducted using ANOVA with the post hoc Bonferroni test in (b) and (d). ^∗∗∗p < 0.001. a.u., arbitrary unit. To see this figure in color, go online.