Retinoid receptors and the induction of apoptosis in canine osteosarcoma cells

Retinoids, all-trans-retinoic acid (ATRA) and 9-cis-retinoic acid (9-cis-RA ), induced morphological changes and apoptosis-like cell death characterize d by cell shrinkage, chromatin condensation and nuclear disintegration in t hree canine osteosarcoma cells, OOS, HOS and POS, at a concentration of 10( -5) M. Both retinoid receptors, RARs and RXRs, were identified in these cel ls. 9-cis-RA bound to both the RXRs and the RARs, whereas ATRA bound to onl y the RARs in these cells. Those results indicate that the induction of apo ptosis in canine osteosarcoma cells may be mediated by the specific control of RARs and RXRs.