In:
Clinical Cancer Research, American Association for Cancer Research (AACR), Vol. 17, No. 9 ( 2011-05-01), p. 2712-2724
Abstract:
Purpose: To elucidate new molecular mechanisms able to downregulate the mRNA levels of key oncogenes, such as B-Myb and E2F1, in a therapeutic perspective. Experimental Design: B-Myb and E2F1 mRNA levels were evaluated in primary B chronic lymphocytic leukemia (B-CLL, n = 10) and acute myeloid leukemia (AML, n = 5) patient cells, in a variety of p53wild-type and p53mutated/deleted leukemic cell lines, as well as in primary endothelial cells and fibroblasts. Knockdown experiments with siRNA for p53 and E2F1 and overexpression experiments with miR34a were conducted to elucidate the role of these pathways in promoting B-Myb downregulation. Results: In vitro exposure to Nutlin-3, a nongenotoxic activator of p53, variably downregulated the expression of B-Myb in primary leukemic cells and in p53wild-type myeloid (OCI, MOLM) and lymphoblastoid (SKW6.4, EHEB) but not in p53mutated (NB4, BJAB, MAVER) or p53deleted (HL-60) leukemic cell lines. The transcriptional repression of B-Myb was also observed in primary normal endothelial cells and fibroblasts. B-Myb downregulation played a critical role in the cell-cycle block in G1 phase induced by Nutlin-3, as shown by transfection experiments with specific siRNA. Moreover, we have provided experimental evidence suggesting that miR-34a is a central mediator in the repression of B-Myb both directly and through E2F1. Conclusions: Owing to the role of B-Myb and E2F1 transcription factors in controlling cell-cycle progression of leukemic cells, the downregulation of these oncogenes by miR-34a suggests the usefulness of therapeutic approaches aimed to modulate the levels of miR-34a. Clin Cancer Res; 17(9); 2712–24. ©2011 AACR.
Type of Medium:
Online Resource
ISSN:
1078-0432
,
1557-3265
DOI:
10.1158/1078-0432.CCR-10-3244
Language:
English
Publisher:
American Association for Cancer Research (AACR)
Publication Date:
2011
detail.hit.zdb_id:
1225457-5
detail.hit.zdb_id:
2036787-9
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