SUPPRESSION OF IN-VITRO MAINTENANCE OF NON-PROMYELOCYTIC MYELOID-LEUKEMIA CLONOGENIC CELLS BY ALL-TRANS-RETINOIC ACID - MODULATING EFFECTS OF DIHYDROXYLATED VITAMIN-D3, ALPHA-INTERFERON AND STEM-CELL FACTOR

In a liquid culture system, all-trans retinoic acid (ATRA), alone and in combination with dihydroxylated vitamin D3 (D3) or alpha interferon (alpha IFN) at concentrations achievable in vivo, could significantly suppress the maintenance of non-promyelocytic myeloid leukemia clonog enic cells (CFU-L) in 9/20, 9/18 and 7/11 cases, respectively. That su ppression was counteracted only slightly by the addition of 'stem cell factor', a cytokine which promotes CFU-L expansion in vitro. Differen tiated cells slightly increased in 5/17 cases only, suggesting the pre valence of anti-proliferative rather than differentiating mechanisms. The present results extend our previous ones and suggest the possible therapeutical value of ATRA+D3 or alpha IFN, even in cases of non-prom yelocytic myeloid leukemia. (C) 1997 Elsevier Science Ltd.