Abstract
The objective of this work was to characterize tumor cell locomotion in response to chemotactic stimulation using a dual-micropipet assay. The assay involves two micropipets. An individual A2058 human melanoma cell was retained, without pressure gradient, in a pipet of approximately 14 μm i.d. A solution of type IV collagen, chosen as the chemotactic source, was placed in another pipet (∼10 μm o.d.) with zero pressure at the pipet tip. The smaller pipet was then inserted into the larger one containing the melanoma cell. The initial chemoattractant concentration (C0) and the distance between the tip of the small pipet and the cell surface (δ) provided a gradient (C0/δ) for tumor cell locomotion toward stimulation. This novel assay provides a direct measure of cell movement: cyclic pseudopod protrusion (Lp) and subsequent cell locomotion (Lc). The influences of different adhesion substrates on cell locomotion were also studied. The peak length inLpprecedes the highest locomotion velocity (dLc/dt) by an apparent lag time.C0/δ influences pseudopod protrusion frequency (fp) anddLc/dt, but not significantly onLp. Substrate adhesions affectdLc/dt, but apparently notLporfp. In conclusion, pseudopod protrusion and substrate adhesion are two necessary but mutually independent factors in tumor cell locomotion.dLc/dtcorrelates with changes inC0/δ, which is in significant correlation withfpbut notLp.
Published Version
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