Effects of epoxycarotenoids, beta-carotene, and retinoic acid on the differentiation and viability of the leukemia cell line NB4 in vitro.
Three all-trans epoxides of beta-carotene (beta-Car), namely, 5,6-epoxy-beta-carotene (5,6-EC), 5,8-epoxy-beta-carotene (5,8-EC) and 5,6,5',6'-diepoxy-beta-carotene (5,6,5',6'-DEC) were synthesized by treatment of beta-carotene with 3-chloroperoxybenzoic acid, were purified chromatographically, and were characterized. The relative potencies (mean +/- S.D.) of 1 microM compounds in inducing the differentiation of NB4 cells, a cell line that contains the chromosomal transposition t(15;17) characteristic of acute promyelocytic leukemia, after 4 days of incubation were: RA: 1.35 +/- 0.16, 5,6-EC: 0.29 +/- 0.01, 5,8-EC: 0.22 +/- 0.05, 5,6,5',6'-DEC: 0.11 +/- 0.02, beta C: 0.09 +/- 0.01, and the control: 0.06 +/- 0.01. The same order of potencies existed at other concentrations tested and at other incubation times. P values for the differences between the inducing activities of successive pairs of compounds at 1 microM were: RA vs. 5,6-EC, < 0.001; 5,6-EC vs. 5,8-EC, < 0.01; 5,8-EC vs. 5,6,5',6'-DEC, < 0.01; 5,6,5',6'-DEC vs. beta-Car, < 0.10; beta-Car vs. control, < 0.005. Similar P values were also obtained for studies at other concentrations and at other incubation times. The viable cell mass at 4 days was inversely proportional to the extent of differentiation (rs = -1.0). The inducing activities of all compounds were dose-dependent. Thus, the 5,6-monoepoxide of beta-carotene, which has not previously been studied as an inducer, showed higher activity in NB4 cell differentiation than the 5,8-monoepoxide, the 5,6,5',6'-diepoxide, or beta-carotene. Possible explanations of these observations are discussed.
Duitsman
P K
PK
Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames 50011, USA.
Barua
A B
AB
Becker
B
B
Olson
J A
JA
D002454:Cell Differentiation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004852:Epoxy Compounds / Q000494:pharmacology*; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D019207:beta Carotene / Q000031:analogs & derivatives / Q000494:pharmacology*
D004852:Epoxy Compounds; D019207:beta Carotene; C073147:5,6-epoxy-beta,beta-carotene; D014212:Tretinoin; C001792:citroxanthin