The Oncogenic Transcription Factor RUNX1/ETO Corrupts Cell Cycle Regulation to Drive Leukemic Transformation

Oncogenic transcription factors such as the leukemic fusion protein RUNX1/ETO, which drives t(8;21) acute myeloid leukemia (AML), constitute cancer-specific but highly challenging therapeutic targets. We used epigenomic profiling data for an RNAi screen to interrogate the transcriptional network maintaining t(8;21) AML. This strategy identified Cyclin D2 (CCND2) as a crucial transmitter of RUNX1/ETO-driven leukemic propagation. RUNX1/ETO cooperates with AP-1 to drive CCND2 expression. Knockdown or pharmacological inhibition of CCND2 by an approved drug significantly impairs leukemic expansion of patient-derived AML cells and engraftment in immunodeficient murine hosts. Our data demonstrate that RUNX1/ETO maintains leukemia by promoting cell cycle progression and identifies G1 CCND-CDK complexes as promising therapeutic targets for treatment of RUNX1/ETO-driven AML.

Limitations in the ability of NB84 to detect metastatic neuroblastoma cells in bone marrow

BACKGROUND

The accurate assessment of metastases is an essential component of the staging process for children with neuroblastoma.

AIMS

To study the sensitivity of the immunohistochemical marker neuroblastoma 84 (NB84) for the detection of bone marrow infiltrates in children with stage 4 neuroblastoma.

METHODS

Primary tumour specimens, bone marrow trephine biopsy specimens and lymph node metastases, taken from children with neuroblastoma that had metastasised to bone marrow, were assessed with a panel of commonly used immunohistochemical markers for neuroblastoma. A comparison was drawn between the sensitivity of the marker NB84 for primary tumours and for bone marrow metastases.

RESULTS

NB84 immunolabelled all pre-chemotherapy and post-chemotherapy (n = 24) paired primary tumour specimens, as well as each of a further 20, unpaired, pre-chemotherapy primary tumour specimens. It also labelled all (n = 4) lymph node metastases. Immunolabelling of bone marrow trephine biopsy specimens (21/33) was less sensitive. Of 16 primary tumour specimens with a paired bone marrow trephine biopsy specimen, all immunostained positive, whereas only 62.5% of bone marrow biopsy specimens immunostained positive for NB84. The number of bone marrow biopsy specimens immunostaining for NB84 was significantly lower than the number of paired primary tumour specimens (p = 0.041).

CONCLUSIONS

NB84 remains a useful marker for the diagnosis of neuroblastoma in primary tumour specimens, but not for neuroblastoma that has metastasised to bone marrow.