Over-expression of nucleophosmin/B23 decreases the susceptibility of human leukemia HL-60 cells to retinoic acid-induced differentiation and apoptosis.
Stable clones of HL-60 cells in which nucleophosmin/B23 was over-expressed were established. Less percentages (4-20%) of nucleophosmin/B23 over-expressed (pCR3-B23) cells exhibited the morphological characteristic of apoptosis as compared with control vector-transfected (pCR3) cells (6-53%) during the 10 microM RA treatment for 1-4 days. In flow cytometry analysis, a block in the G1 phase was noted in all the pCR3-B23 and pCR3 cells after 2 days of 10 microM RA treatment and continued to be observed at all times measured up to 6 days. Smaller peaks of apoptotic cells with less than G1 DNA content were observed in pCR3-B23 as compared with pCR3 cells after 4-6 days of 10 microM RA treatment. As measured by expressions of differentiation markers and the functional assessment of the ability to reduce nitroblue-tetrazolium, our results further showed that over-expression of nucleophosmin/B23 decreased the response of the cells to RA-induced differentiation. Less cleavage of PARP and in vitro caspase-3 activity were observed in PCR3-B23 cells as compared with pCR3 cells treated with 10 microM RA for 3-4 days. IRF-1 was induced after 6 hr of 10 microM RA treatment in the pCR3-B23 and pCR3 cells. Significantly more nucleophosmin/B23 was co-immunoprecipitated with IRF-1 from pCR3-B23 cells than from pCR3 cells during RA treatment (10 microM; 24 hr, 96 hr). The IRF-1 transcriptional activity was found to be attenuated in pCR3-B23 cells as compared with pCR3 cells during the treatment of cells with RA. Nucleophosmin/B23, through interacting with IRF-1, plays an important role in the control of the susceptibility of cells to RA-induced differentiation and apoptosis.
Hsu
C Y
CY
Graduate Institute of Pharmacology, National Yang Ming University, Taiwan, Republic of China.
Yung
B Y
BY
D017209:Apoptosis / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000032:analysis / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D050856:Interferon Regulatory Factor-1; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology*; D000090243:Nucleophosmin; D010750:Phosphoproteins / Q000032:analysis / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D014158:Transcription, Genetic; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology*
D004268:DNA-Binding Proteins; C494257:IRF1 protein, human; D050856:Interferon Regulatory Factor-1; C000716967:NPM1 protein, human; D009687:Nuclear Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; D000090243:Nucleophosmin; D014212:Tretinoin