ABSENCE OF CELL-SURFACE ANNEXIN-V IS ACCOMPANIED BY DEFECTIVE COLLAGEN MATRIX BINDING IN THE SWARM RAT CHONDROSARCOMA

Annexin V has been characterized as a major collagen type II binding c ell-surface component of normal chondrocytes and is also called anchor in CII in chondrogenic populations. Herein we present evidence that in vitro cultured Swarm rat chondrosarcoma cells are not capable of bind ing collagen type II in significant quantities to their surfaces, as c ompared to normal rat chondrocytes. This finding coincides with a defi ciency of annexin V on the surface of these cells. A small quantity of an intracellular polypeptide could be detected which is immunological ly crossreactive (w)ith annexin V but displayed a mobility in SDS-PACE of less than 34 kD compared to the M-r 36 kD of intact rat annexin V. By immunohistochemistry the protein could be localized in the cytopla sm of in vitro and in vivo grown tumor cells. By reverse transcription -polymerase chain reaction and Northern blot analysis, a regular-sized mRNA for annexin V could be detected in the chondrosarcoma cells that is expressed in only slightly lower quantities than in normal chondro cytes. Taken together, the data suggest a modified processing or turno ver for annexin V in the chondrosarcoma excluding it from being a func tionally active collagen type II binding protein. The findings support the hypothesis of cell-surface annexin V as a key component for the f ormation of the pericellular matrix of chondrocytes. (C) 1997 Wiley-Li ss, Inc.