Repression of BMI1 in normal and leukemic human CD34(+) cells impairs self-renewal and induces apoptosis.
High expression of BMI1 in acute myeloid leukemia (AML) cells is associated with an unfavorable prognosis. Therefore, the effects of down-modulation of BMI1 in normal and leukemic CD34(+) AML cells were studied using a lentiviral RNA interference approach. We demonstrate that down-modulation of BMI1 in cord blood CD34(+) cells impaired long-term expansion and progenitor-forming capacity, both in cytokine-driven liquid cultures as well as in bone marrow stromal cocultures. In addition, long-term culture-initiating cell frequencies were dramatically decreased upon knockdown of BMI1, indicating an impaired maintenance of stem and progenitor cells. The reduced progenitor and stem cell frequencies were associated with increased expression of p14ARF and p16INK4A and enhanced apoptosis, which coincided with increased levels of intracellular reactive oxygen species and reduced FOXO3A expression. In AML CD34(+) cells, down-modulation of BMI1 impaired long-term expansion, whereby self-renewal capacity was lost, as determined by the loss of replating capacity of the cultures. These phenotypes were also associated with increased expression levels of p14ARF and p16INK4A. Together our data indicate that BMI1 expression is required for maintenance and self-renewal of normal and leukemic stem and progenitor cells, and that expression of BMI1 protects cells against oxidative stress.
Rizo
Aleksandra
A
Department of Cell Biology, Section Stem Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
Olthof
Sandra
S
Han
Lina
L
Vellenga
Edo
E
de Haan
Gerald
G
Schuringa
Jan Jacob
JJ
D018952:Antigens, CD34 / Q000378:metabolism*; D017209:Apoptosis / Q000235:genetics*; D001772:Blood Cell Count; D001773:Blood Cells / Q000187:drug effects / Q000378:metabolism; D049109:Cell Proliferation; D002478:Cells, Cultured; D005312:Fetal Blood / Q000166:cytology; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007231:Infant, Newborn; D015470:Leukemia, Myeloid, Acute / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics; D063150:Polycomb Repressive Complex 1; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D034622:RNA Interference / Q000502:physiology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D012097:Repressor Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism
D018952:Antigens, CD34; C069077:BMI1 protein, human; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D012097:Repressor Proteins; D063150:Polycomb Repressive Complex 1