Enhanced expression of DNA topoisomerase II by recombinant human granulocyte colony-stimulating factor in human leukemia cells.
The effect of recombinant human granulocyte colony-stimulating factor (G-CSF) on DNA topoisomerase II (topo II) expression was studied in two human acute myelogenous leukemia cell lines, NKM-1 and NOMO-1, which express G-CSF receptor and proliferate in response to exogenous G-CSF. Northern blot analysis revealed that the level of topo II mRNA in 16-h stimulated cells in serum-free medium with G-CSF (10 ng/ml) was approximately 2-fold higher than that in cells without G-CSF. Enhanced topo II mRNA expression was detectable within 3 h after the addition of G-CSF. Topo II activity in crude nuclear extracts from 16-h G-CSF-stimulated cells was also found to be approximately 2-fold greater than that from unstimulated cells. According to in vitro cytotoxic assay, the sensitivity of G-CSF-stimulated cells to intercalating (daunorubicin) and nonintercalating (etoposide) topo II-targeting drugs increased significantly, whereas no enhancement of sensitivity was observed with an alkylating agent (4-hydroperoxycyclophosphamide). The augmented drug sensitivity observed was not due to the increased level of drug transport, as suggested by the similar extent of [3H]etoposide uptake between G-CSF-stimulated and unstimulated cells. By measuring the topo II mRNA and the cytotoxicity of the above mentioned drugs, we obtained essentially the same results in G-CSF-responsive leukemia cells isolated from three acute myeloblastic leukemia patients, as observed in the cultured cell lines. These findings strongly suggest that the sensitivity to "topo II-targeting drugs" could be augmented by exogenous G-CSF through elevated topo II activity in G-CSF-responsive leukemia cells.
First Department of Internal Medicine, Nagoya University School of Medicine, Japan.
M
M
Towatari
Y
Y
Ito
Y
Y
Morishita
M
M
Tanimoto
K
K
Kawashima
Y
Y
Morishima
T
T
Andoh
H
H
Saito
D015152:Blotting, Northern; D003520:Cyclophosphamide / Q000031:analogs & derivatives / Q000633:toxicity; D004250:DNA Topoisomerases, Type II / Q000235:genetics* / Q000378:metabolism; D003630:Daunorubicin / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D005047:Etoposide / Q000378:metabolism / Q000633:toxicity; D015870:Gene Expression / Q000187:drug effects; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D011994:Recombinant Proteins; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011994:Recombinant Proteins; D016179:Granulocyte Colony-Stimulating Factor; D005047:Etoposide; D003520:Cyclophosphamide; D004250:DNA Topoisomerases, Type II; C011272:perfosfamide; D003630:Daunorubicin