title: Cell cycle-dependence of HL-60 cell deformability.
abstract: 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.
authors.affiliation: Department of Biophysics, University of Rochester School of Medicine and Dentistry, New York 14642, USA. mts1@medinfo.rochester.edu
authors.forename: M A
authors.initials: MA
authors.lastname: Tsai
authors.forename: R E
authors.initials: RE
authors.lastname: Waugh
authors.forename: P C
authors.initials: PC
authors.lastname: Keng
mesh_terms: D000199:Actins / Q000502:physiology; D001696:Biomechanical Phenomena; D055592:Biophysical Phenomena; D001703:Biophysics; D002453:Cell Cycle / Q000502:physiology*; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D048429:Cell Size / Q000502:physiology; D003078:Colchicine / Q000494:pharmacology; D003571:Cytochalasin B / Q000031:analogs & derivatives / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000502:physiology; D018922:HL-60 Cells / Q000502:physiology*; D006801:Humans; D007962:Leukocytes / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D008833:Microcirculation / Q000502:physiology; D008870:Microtubules / Q000187:drug effects / Q000502:physiology; D014783:Viscosity
chemical_list: D000199:Actins; C024794:dihydrocytochalasin B; D003571:Cytochalasin B; D003078:Colchicine