INDUCTION OF SPERMIDINE SPERMINE N-1-ACETYLTRANSFERASE BY INTERFERON TYPE-I IN CELLS OF HEMATOPOIETIC ORIGIN/

A number of novel genes activated by type I interferons (IFNs) were id entified by differential display. Of five induced genes examined, four were of unknown function. However, one gene sequence was identical to the human spermidine/spermine N-1-acetyltransferase, the rate-limitin g enzyme in polyamine catabolism, This enzyme was induced by type I IF Ns in a series of hematopoietic cell lines, including Daudi, HL-60, HP BMa, and Wil-2. No induction above constitutive levels occurred in a c ell line of epithelial (ME180) or liver (HepG2) origin following treat ment with type I IFN, Spermidine/spermine N-1-acetyltransferase was no t induced by IFN-gamma in Daudi or ME180 cells. That induction occurre d not only at the level of transcription but also at the enzyme level was confirmed by direct enzyme assays, As the levels of polyamines are related to cell viability, we propose that induction of this enzyme b y IFN may be directly related to the anti-proliferative response to ty pe I IFNs.