Expression of the miR-17-92 polycistron in chronic myeloid leukemia (CML) CD34+ cells.

Aberrant micro RNA (miRNA) expression has been described in human malignancies including B-cell lymphomas. We here report BCR-ABL- and c-MYC-dependent regulation of miRNA expression in chronic myeloid leukemia (CML) using microarray analysis (miCHIP) and miRNA-specific quantitative real-time reverse transcriptase-polymerase chain reaction (miR-qRT-PCR). In 3 bcr-abl-positive cell lines, expression of miRNAs encoded within the polycistronic miR-17-92 cluster is specifically down-regulated (2- to 5-fold) by both imatinib treatment and anti-BCR-ABL RNA interference (RNAi). In addition, anti-c-MYC RNAi reduces miR-17-92 expression in K562 cells in which miRNAs can specifically repress reporter gene expression, as demonstrated by specific miRNA inhibition with antagomirs. Furthermore, lentivirus-mediated overexpression of polycistronic miRNAs in K562 cells confers increased proliferation, partial resistance against anti-c-MYC RNAi, and enhanced sensitivity to imatinib-induced cell death. Finally, we determined miR-17-92 expression in purified normal (n = 4), early chronic-phase (CP) (n = 24), and blast-crisis (BC) (n = 7) CML CD34(+) cells and found up-regulation of polycistronic pri-miRNA transcripts in CML and mature miRNAs in CP but not in BC CML. These data are in accordance with a BCR-ABL-c-MYC-miR-17-92 pathway that mediates enhanced miRNA expression in CP but not BC CML CD34(+) cells. Altered miRNA expression may contribute to the pathophysiology of the disease and may provide potential targets for therapeutic intervention.

[1]  Thomas D. Schmittgen,et al.  Analysis of relative gene expression data using real-time quantitative PCR and the 2(-Delta Delta C(T)) Method. , 2001, Methods.

[2]  David Levens,et al.  Disentangling the MYC web , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[3]  B. Calabretta,et al.  Transformation of hematopoietic cells by BCR/ABL requires activation of a PI‐3k/Akt‐dependent pathway , 1997, The EMBO journal.

[4]  H. Horvitz,et al.  MicroRNA expression profiles classify human cancers , 2005, Nature.

[5]  C. Burge,et al.  Prediction of Mammalian MicroRNA Targets , 2003, Cell.

[6]  A. Ganser,et al.  Stable RNA interference (RNAi) as an option for anti-bcr-abl therapy , 2005, Gene Therapy.

[7]  A. Ganser,et al.  Modulation of Gene Expression by Lentiviral-Mediated Delivery of Small Interfering RNA , 2003, Cell cycle.

[8]  C. Croce,et al.  Human microRNA genes are frequently located at fragile sites and genomic regions involved in cancers. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[9]  N. Rajewsky,et al.  Silencing of microRNAs in vivo with ‘antagomirs’ , 2005, Nature.

[10]  D. Bartel.  MicroRNAs Genomics, Biogenesis, Mechanism, and Function , 2004, Cell.

[11]  Arndt Borkhardt,et al.  High expression of precursor microRNA‐155/BIC RNA in children with Burkitt lymphoma , 2004, Genes, chromosomes & cancer.

[12]  C. Croce,et al.  MicroRNA profiling reveals distinct signatures in B cell chronic lymphocytic leukemias. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[13]  C. Croce,et al.  A microRNA expression signature of human solid tumors defines cancer gene targets , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[14]  S. Lowe,et al.  A microRNA polycistron as a potential human oncogene , 2005, Nature.

[15]  V. Ambros.  The functions of animal microRNAs , 2004, Nature.

[16]  F. Holstege,et al.  Specific inhibition of gene expression using a stably integrated, inducible small‐interfering‐RNA vector , 2003, EMBO reports.

[17]  Peter F Stadler,et al.  Molecular evolution of a microRNA cluster. , 2004, Journal of molecular biology.

[18]  C. Sawyers,et al.  Dominant negative MYC blocks transformation by ABL oncogenes , 1992, Cell.

[19]  A. D’Andrea,et al.  The C-Terminus of c-Abl Is Required for Proliferation and Viability Signaling in a c-Abl/Erythropoietin Receptor Fusion Protein , 1998 .

[20]  Vladimir Benes,et al.  A sensitive array for microRNA expression profiling (miChip) based on locked nucleic acids (LNA). , 2006, RNA.

[21]  V. Kim,et al.  The nuclear RNase III Drosha initiates microRNA processing , 2003, Nature.

[22]  Hiroyuki Tagawa,et al.  Identification and characterization of a novel gene, C13orf25, as a target for 13q31-q32 amplification in malignant lymphoma. , 2004, Cancer research.

[23]  Y. Yatabe,et al.  A polycistronic microRNA cluster, miR-17-92, is overexpressed in human lung cancers and enhances cell proliferation. , 2005, Cancer research.

[24]  F. Slack,et al.  RAS Is Regulated by the let-7 MicroRNA Family , 2005, Cell.

[25]  Kathryn A. O’Donnell,et al.  c-Myc-regulated microRNAs modulate E2F1 expression , 2005, Nature.

[26]  Joel S Parker,et al.  Extensive post-transcriptional regulation of microRNAs and its implications for cancer. , 2006, Genes & development.

[27]  A. Ganser,et al.  Lentiviral gene transfer into peripheral blood-derived CD34+ NOD/SCID-repopulating cells. , 2002, Blood.

[28]  Hui-Kuan Lin,et al.  Jak2 is involved in c-Myc induction by Bcr-Abl , 2002, Oncogene.

[29]  Kathryn A. O’Donnell,et al.  The c-Myc target gene network. , 2006, Seminars in cancer biology.