Analysis of genes involved in proliferation and differentiation of megakaryopoiesis using a human megakaryoblastic leukemia cell line

在新建立的人急性巨核母细胞白血病细胞系（MEG-01）中，在TPA诱导的成熟过程中检测了c-abl、c-fos、c-sis和myc基因家族（c-myc、L-myc和N-myc）的表达，TPA处理后，该细胞系表现出显性形态变化和/或细胞谱系特异性功能蛋白的产生。成熟诱导后，细胞系中c-myc癌基因的组成性表达迅速下降，并在4小时内基本无法检测到。在MEG-01细胞中，c-myc水平在24小时后完全恢复，而在人急性单细胞白血病细胞系NOMO-1细胞中仍无法检测到c-myc。C-fos RNA在TPA处理后15 min内被诱导，在1 h内达到最高转录水平，随后下降。c-abl、L-myc和N-myc的表达在未诱导和诱导条件下均未检测到。放线菌素D对tpa诱导细胞的c-myc表达的诱导降低没有影响，而放线菌素D的存在降低了NOMO-1细胞中c-myc转录本的稳定性。DNAse I对未诱导和诱导细胞系的核酸DNA的处理表明，c-myc基因的单个DNAse I超敏位点5'的丢失伴随着NOMO-1细胞中c-myc表达的降低。

Expression of c-abl, c-fos, c-sis and myc gene family (c-myc, L-myc and N-myc) was examined during 12-O-tetradecanoyl-phorbol-13-acetate (TPA) induced maturation in a newly established human acute megakaryoblastic leukemia cell line (MEG-01), which shows dominant morphological changes and/or productions of cell lineage specific functional proteins after TPA treatment. Upon maturation induction, constitutive expression of c-myc oncogene in the cell line was rapidly decreased and become fairly undetectable within 4 h. The level of c-myc was fully recovered after 24 h in MEG-01 cells, whereas it remained undetectable in NOMO-1 cells, a human acute monoblastic leukemia cell line. C-fos RNA was induced within 15 min after TPA treatment, reached to the maximum transcriptional level in 1 h and thereafter decreased. Expression of c-abl, L-myc and N-myc was detected in neither uninduced nor induced condition. Actinomycin D treatment on TPA-induced cells made no effect on the induced reduction of c-myc expression in MEG-01 cells, whereas the stability of c-myc transcripts in NOMO-1 cells was decreased by the presence of actinomycin D. DNAse I treatment of nucleic DNA of both uninduced and induced cell lines showed that the loss of a single DNAse I hypersensitive site 5' of the c-myc gene was accompanied with reduced c-myc expression in NOMO-1 cells.