Dexamethasone does not counteract the response of acute promyelocytic leukaemia cells to all-trans retinoic acid

Retinoic acid syndrome is a serious condition that may complicate the treat ment of acute promyelocytic leukaemia patients, This syndrome may be treate d effectively with high-dose corticosteroid therapy and, as a result, many patients with acute promyelocytic leukaemia receive dexamethasone at some p oint during treatment. We investigated whether dexamethasone would also ant agonize the beneficial effects of retinoic acid, In t(15:17)-positive NB4 c ells, dexamethasone did not affect the retinoic acid induced differentiatio n, normalization of PML-nuclear bodies or the induction of thrombomodulin m RNA. Finally, dexamethasone did not inhibit the anti-proliferative effect o f retinoic acid but rather showed anti-proliferative activity itself.