Functional characterization of high levels of meningioma 1 as collaborating oncogene in acute leukemia

Abstract

Retroviral expression of leukemogenic oncogenes in the murine hematopoietic system is essential but not sufficient to induce acute leukemia. Proviral integration-mediated elevated expression of the meningioma 1 (MN1) oncogene suggested MN1 acting as cooperating event in mixed-lineage leukemia 1 (MLL) and eleven nineteen leukemia (ENL)-induced murine leukemia. Indeed, co-expression of MN1 with MLL-ENL enhanced transformation in vivo, and resulted in a significantly reduced latency for induction of an aggressive acute leukemia when compared with MN1 or MLL-ENL alone. In addition, coexpression of MN1 increased the granulocyte macrophage progenitor cell population with leukemia-initiating properties as shown in secondary transplantation experiments. Gene expression profiling experiments identified putative downstream MN1 targets, of which FMS-like tyrosine kinase 3 (FLT3) and CD34 were upregulated in both MN1-overexpressing murine leukemias and in pediatric acute leukemias with high MN1 levels. Interestingly, small interfering RNA (siRNA)-mediated MN1 knockdown resulted in cell cycle arrest and impaired clonogenic growth of human leukemia cell lines with high MN1 levels. Our work shows for the first time that high MN1 levels are important for the growth of leukemic cells, and that increased MN1 expression can synergize with MLL-ENL and probably other transforming fusion genes in leukemia induction through a distinct gene expression program that is able to expand the leukemia-initiating cell population.

Potent co-operation between the NUP98-NSD1 fusion and the FLT3-ITD mutation in acute myeloid leukemia induction

“…These different integration events could theoretically not only provide clonal advantage, but also result in different expression levels of the viral encoded transgenes. 24 However, in contrast to FLT3-ITD, we found no significantly different expression levels of the NUP98-NSD1 fusion or its proposed downstream target the HoxA gene cluster (HoxA5, HoxA7, HoxA9, HoxA10) in cells from both experiments ( Figure 5A).…”

“…24 PCR amplicons were separated on a 2% agarose gel, purified and cloned into pCR2.1-TOPO (Invitrogen) and sequenced. The obtained sequences were analyzed using BLAST (NCBI).…”

Validation and Structural Characterization of the LEDGF/p75–MLL Interface as a New Target for the Treatment of MLL-Dependent Leukemia

“…Murine stem cell virus-based (pMSCV) retroviral vector production was performed as described previously (28). Production of Simian immunodeficiency virus (SIV)-derived vectors was performed as described earlier (29).…”

Modeling de novo leukemogenesis from human cord blood with MN1 and NUP98HOXD13

“…4 Conversely, loss of MN1 expression impaired the proliferation and clonogenic activity of cells from a human leukemia cell line. 5 We previously identified HOXA9 and NUP98-HOXD13 (ND13) as potent collaborating genes with MN1 in leukemic transformation in mice, 6 and we identified MN1 as a cofactor of the HOXA9/MEIS1 transcriptional complex. 7 In this report, we investigate the transforming potential of MN1 in human CB cells and present a model of stepwise transformation to human AML.…”