Selective cytotoxicity of withaphysalins in myeloid leukemia cell lines versus peripheral blood mononuclear cells.
Withaphysalins are C(28)-steroidal lactones structurally based on the ergostane skeleton that possess antiproliferative activity against tumor cell lines. In the present study, the antileukemic actvity of withaphysalin O (1), M (2), and N (3) isolated from Acnistus arborescens, against two leukemic cell lines, HL-60 and K562, was evaluated, and the cytotoxicity compared with the effects on peripheral blood mononuclear cells (PBMC). All tested compounds reduced the number of viable cells of the tumor cell lines after 24 h of exposure, except for compound 2 against the K562 cell line. The reduction was time-and concentration-dependent, and the IC(50) values ranged from 0.7 to 3.5 microM after 72 h of incubation. In addition to the growth inhibitory properties, the drugs decreased DNA synthesis after 24 h of drug exposure evaluated by the 5-bromo-2 -deoxyuridine incorporation method. None of the tested compounds reduced the number of PBMC (IC(50)>20 microM) after 72 h of incubation, in contrast to doxorubicin that decreased viable cells and increased non-viable cells even after 24 h of incubation. Morphological analysis of treated cells using hematoxylin/eosin staining indicated the presence of necrotic cells for all tested compounds in HL-60, confirmed by the use of acridine orange/ethidium bromide staining. In addition to necrotic cells, K562 cells showed morphological alterations consistent with apoptosis.
Rocha
Danilo Damasceno
DD
Departamento de Fisiologia e Farmacologia, Universidade Federal do Ceará, Caixa Postal 3157, 60430-270 Fortaleza, Ceará, Brazil.
Militão
Gardenia Carmen Gadelha
GC
Veras
Maria Leopoldina
ML
Pessoa
Otília Deusdênia Loiola
OD
Silveira
Edilberto Rocha
ER
Alves
Ana Paula Negreiros Nunes
AP
de Moraes
Manoel Odorico
MO
Pessoa
Cláudia
C
Costa-Lotufo
Letícia Veras
LV
D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects*; D004261:DNA Replication / Q000187:drug effects; D004875:Ergosterol / Q000031:analogs & derivatives* / Q000494:pharmacology; D018922:HL-60 Cells; D006801:Humans; D007951:Leukemia, Myeloid / Q000378:metabolism* / Q000473:pathology; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D012632:Secosteroids / Q000494:pharmacology*
D012632:Secosteroids; C486267:withaphysalin M; C486265:withaphysalin N; C486266:withaphysalin O; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D004875:Ergosterol