Cell cycle-dependence of HL-60 cell deformability

• Published in: Biophysical journal 1996-04, Vol.70 (4), p.2023-2029
• Main Authors: Tsai, M.A., Waugh, R.E., Keng, P.C.
• Format: Article
• Language: English
• Subjects: Actins - physiology; Biomechanical Phenomena; Biophysical Phenomena; Biophysics; Cell Cycle - physiology; Cell Movement - drug effects; Cell Movement - physiology; Cell Size - physiology; Colchicine - pharmacology; Cytochalasin B - analogs & derivatives; Cytochalasin B - pharmacology; Cytoskeleton - drug effects; Cytoskeleton - physiology; HL-60 Cells - physiology; Humans; Leukocytes - cytology; Leukocytes - drug effects; Leukocytes - physiology; Microcirculation - physiology; Microtubules - drug effects; Microtubules - physiology; Viscosity
• ISSN: 0006-3495; 1542-0086
• DOI: 10.1016/S0006-3495(96)79768-0

In this study, the role of cytoskeleton in HL-60 deformability during the cell cycle was investigated. G1, S, and G2/M cell fractions were separated by centrifugal elutriation. Cell deformability was evaluated by pipette aspiration. Tested at the same aspiration pressures, S cells were found to be less deformable than G1 cells. Moreover, HL-60 cells exhibited power-law fluid behavior: mu = mu c(gamma m/ gamma c)-b, where mu is cytoplasmic viscosity, gamma m is mean shear rate, mu c is the characteristic viscosity at the characteristic shear rate gamma c, and b is a material constant. At a given shear rate, S cells (mu c = 276 +/- 14 Pa.s, b = 0.51 +/- 0.03) were more viscous than G1 cells (mu c = 197 +/- 25, b = 0.53 +/- 0.02). To evaluate the relative importance of different cytoskeletal components in these cell cycle-dependent properties, HL-60 cells were treated with 30 microM dihydrocytochalasin B (DHB) to disrupt F-actin or 100 microM colchicine to collapse microtubules. DHB dramatically softened both G1 and S cells, which reduced the material constants mu c by approximately 65% and b by 20–30%. Colchicine had a limited effect on G1 cells but significantly reduced mu c of S cells (approximately 25%). Thus, F-actin plays the predominate role in determining cell mechanical properties, but disruption of microtubules may also influence the behavior of proliferating cells in a cell cycle-dependent fashion.