TAXOL-TREATED FIBROBLASTS ACQUIRE AN EPITHELIOID SHAPE AND A CIRCULARPATTERN OF ACTIN BUNDLES

The effects of two microtubule-specific drugs, taxol and colcemid, upo n the cell shape and cytoskeleton of several types of cultured fibrobl astic cells were compared. While colcemid depolymerized completely the whole microtubular system, taxol induced decentralization of this sys tem, leading to formation of numerous free microtubules filling the ce ntral cytoplasm. Morphometric determinations of two cell shape paramet ers, dispersion and elongation (G. Dunn and A. Brown, J. Cell Sci. (19 86) 83, 313-340), have shown that, in all the tested cultures, taxol i nduced significantly larger decreases of average dispersion than colce mid; in addition, most taxol-treated cells, but not colcemid-treated o nes, developed circumferential bundles of actin microfilaments instead of straight bundles. These results show that decentralization of the microtubular system, in contrast to its complete depolymerization, lea ds to the transformation of a polarized ''fibroblast-like'' cell morph ology to an ''epithelioid'' morphology characterized by the smooth dis coid cell shape and a circular actin pattern. Possible mechanisms of t his transformation are briefly discussed. (C) 1994 Academic Press, Inc .