ZK7, a novel zinc finger gene, is induced by vascular endothelial growth factor and inhibits apoptotic death in hematopoietic cells.

Vascular endothelial growth factor (VEGF) inhibits radiation-induced apoptosis in the leukemia cell line, CMK86 (O. Katoh et al., Cancer Res., 55: 5687-5692, 1995). To elucidate the molecular mechanisms underlying this inhibitory effect of VEGF, we attempted to identify a transcription factor involved in the cellular response to VEGF stimulation. We cloned the cDNA of a novel Kruppel-type zinc finger (ZNF) gene, ZK7, from a cDNA library constructed from the human leukemia cell line CMK86 after incubation with VEGF. This cDNA encoded a protein of 289 amino acids, which contained a Kruppel-associated box A-box domain at the NH2 terminus and seven ZNF motifs at the COOH terminus. These ZNF motifs were identical to those of HZF16 (M. Saleh et al., Am. J. Hum. Genet., 52: 192-203, 1993). ZK7 and HZF16 genes appear to be the splice variants transcribed from the same gene. Northern blotting and quantitative reverse transcription-PCR analysis revealed that expression of ZK7 mRNA in CMK86 cells and human hematopoietic progenitor cells was increased after VEGF stimulation, whereas that of HZF16 mRNA remained unchanged. To examine the function of ZK7 protein, we generated clones of a human monocytoid leukemia cell line, U937, which were stably transfected with ZK7 or HZF16 cDNA. Importantly, ZK7-overexpressing cells had lower sensitivity to ionizing radiation and the chemotherapeutic agent etoposide than U937 parent cells or HZF16-overexpressing cells. Therefore, ZK7 protein may be involved in the inhibitory effect of VEGF on apoptotic cell death in human hematopoietic cells.