Treatment of HL60 cells with various combinations of retinoids and 1 alpha,25 dihydroxyvitamin D3 results in differentiation towards neutrophils or monocytes or a failure to differentiate and apoptosis
Bunce, C.M.; Wallington, L.A.; Harrison, P.; Williams, G.R.; Brown, G.
Leukemia 9(3): 410-418
1995
ISSN/ISBN: 0887-6924 PMID: 7885039 Document Number: 446803
It is well documented that treatment of serum-grown HL60 cells with 10-7 M all-trans retinoic acid (all-trans RA) induces neutrophil differentiation, whereas treatment with 10-7 M 1-alpha,25 dihydroxyvitamin D-3(D-3) induces differentiation towards monocytes. in recent investigations, using serum-free grown HL60 cells, we observed that all-trans RA, at 10-7 M, did not induce neutrophil differentiation and that all-trans RA, at 10-8 M, reduced the D-3 concentration required for monocyte differentiation to 5 times 10-9 M. In this study, co-operative interactions between all-trans and 9-cis RA and D-3 which promote neutrophil and monocyte differentiation of HL60 cells have been analysed in detail. Treatment of serum-free grown HL60 cells with 5 times 10-7 M all-trans RA or 9-cis RA resulted in sub-optimal neutrophil differentiation (up to 25% mature cells). As shown for all-trans RA, 9-cis RA cooperated with D-3 to promote monocyte differentiation. Culture of HL60 cells in 5 times 10-7 M 9-cis RA together with a wide range of concentrations of D-3 resulted in promotion of neutrophil differentiation at 10-15-10-12 D-3, a failure to differentiate and apoptosis at 10-11-10-10 M D-3, followed by co-operativity between 9-cis RA and 5 times 10-9 M D-3 in inducing monocyte differentiation in the absence of neutrophil differentiation. Similar results were obtained when HL60 cells were treated with 5 times 10-7 all-trans RA together with a wide range of concentrations of D-3. Cross titration analyses of the effects of 9-cis RA and D-3 on HL60 cell differentiation were undertaken to determine the boundaries of the concentrations of each agent, alone and in combination, that give rise to optimal neutrophil and monocyte differentiation of HL60 cells. The observed co-operativities between either 9-cis RA or all-trans RA and D-3 have important implications for the use of combinations of these agents in differentiation therapy.