Robertson K A, Hill D P, Kelley M R, Tritt R, Crum B, Van Epps S, Srour E, Rice S, Hromas R
Herman B Wells Center for Pediatric Research, Indiana University Medical Center, Indianapolis 46202-5225, USA.
Leukemia. 1998 May;12(5):690-8. doi: 10.1038/sj.leu.2401005.
The myeloid zinc finger gene, MZF-1, is a hematopoietic transcription factor expressed in developing myeloid cells. To characterize further the role of MZF-1 in myelopoiesis, we used retroviral gene transduction to overexpress MZF-1 in HL-60 cells to produce HL-60-MZF-1 cells. HL-60 cells respond to retinoic acid (RA) with growth inhibition, granulocytic differentiation and apoptosis. However, HL-60-MZF-1 cells exposed to RA continue to proliferate in response to RA as evidenced by a higher percentage of cells in S phase, higher peak cell counts, and later peak cell counts. Morphologic differentiation of the RA-induced HL-60-MZF-1 cells is delayed with half as many of the HL-60-MZF-1 cells compared to the wild-type HL-60 cells that are differentiated after 3 days of RA, although both cells types responded with 80-95% mature granulocytes after 6 days of RA. Apoptosis was delayed in the MZF-1 transduced cells as measured by internucleosomal DNA fragmentation patterns, the terminal transferase end labeling reaction (TUNEL), and quantitation of fragmented DNA by the diphenylamine reaction. Several markers of differentiation were identical in both HL-60 and HL-60-MZF-1 cells including CD11b, CD33, CD34, CD13, CD16 and CD14. However, following 6 days of RA, only half as many HL-60-MZF-1 cells expressed CD18 compared to the wild-type HL-60 cells. Expression of the bcl-2 proto-oncogene transcript and protein was higher in the HL-60-MZF-1 cells compared to wild-type HL-60s and expression persisted for 5 days following RA in the HL-60-MZF-1 cells compared to only 3 days in the parental HL-60 cells suggesting that bcl-2 may contribute to the inhibition of apoptosis. Overexpression of MZF-1 had no effect on PMA-induced monocyte/macrophage differentiation of HL-60 cells. Together these findings indicate that MZF-1 can stimulate cell proliferation and delay RA-induced differentiation and apoptosis in HL-60 cells. MZF-1 may function in a similar role in myelopoiesis allowing myeloid precursors to expand their numbers before going on to terminally differentiate.
髓系锌指基因MZF-1是一种在发育中的髓系细胞中表达的造血转录因子。为了进一步明确MZF-1在髓系造血中的作用，我们利用逆转录病毒基因转导技术使HL-60细胞中MZF-1过表达，从而产生HL-60-MZF-1细胞。HL-60细胞在视黄酸（RA）作用下会出现生长抑制、粒细胞分化和凋亡。然而，暴露于RA的HL-60-MZF-1细胞会继续增殖，这可通过S期细胞比例更高、细胞计数峰值更高以及细胞计数峰值出现时间更晚得到证明。RA诱导的HL-60-MZF-1细胞的形态分化延迟，与野生型HL-60细胞相比，HL-60-MZF-1细胞数量只有其一半，野生型HL-60细胞在RA处理3天后就开始分化，不过两种细胞类型在RA处理6天后都有80%-95%的细胞分化为成熟粒细胞。通过核小体间DNA片段化模式、末端转移酶末端标记反应（TUNEL）以及二苯胺反应对片段化DNA进行定量分析发现，MZF-1转导细胞中的凋亡延迟。HL-60和HL-60-MZF-1细胞中的几种分化标志物相同，包括CD11b、CD33、CD34、CD13、CD16和CD14。然而，在RA处理6天后，与野生型HL-60细胞相比，表达CD18的HL-60-MZF-1细胞数量只有其一半。与野生型HL-60细胞相比，HL-60-MZF-1细胞中bcl-2原癌基因转录本和蛋白的表达更高，并且在RA处理后，HL-60-MZF-1细胞中bcl-2的表达持续5天，而亲本HL-60细胞中仅持续3天，这表明bcl-2可能有助于抑制凋亡。MZF-1的过表达对PMA诱导的HL-60细胞向单核细胞/巨噬细胞的分化没有影响。这些研究结果共同表明，MZF-1可以刺激细胞增殖，并延迟RA诱导的HL-60细胞分化和凋亡。MZF-1在髓系造血中可能发挥类似作用，使髓系前体细胞在终末分化之前能够增加其数量。
