NF-M trans-activates the human DNA topoisomerase II alpha promoter independently of c-Myb in HL-60 cells

Identifying transcriptional regulators of DNA topoisomerase II alpha (topo II alpha) is essential to decipher the mechanisms underlying leukemia cell resistance to topo II-directed antitumor drugs. We have previously reported that the proto-oncogene transcription factor c-Myb transactivates the topo II alpha promoter in several hematopoietic cell lines. Currently, we investigate whether NF-M, a C/EBP beta family member, cooperates with c-Myb in activating topo II alpha transcription. Although NF-M is the most efficacious trans-activator of topo II alpha that we have examined (approximately 38-fold over basal), NF-M does not appear to be involved in the endogenous transcriptional regulation of topo II alpha. Interestingly, we report that the sodium butyrate-dependent induction of the topo II alpha promoter observed previously appears to be mediated by c-Myb, independent of NF-M.