Declined asparagine synthetase mRNA expression and enhanced sensitivity to asparaginase in HL-60 cells committed to monocytic differentiation

Abstract

During 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced differentiation of human promyelocytic leukemia HL-60 cells toward maturing monocytes/macrophages, asparagine synthetase (ASNS) mRNA expression declined time and dose-dependently. The effect of TPA was inhibited by inhibitors for PKC and MEK 1/2, but not by those for JNK and p38 MAPK. Combination treatment with TPA and asparaginase synergistically enhanced the growth retardation accompanied by apoptotic cell death characterized by internucleosomal DNA fragmentation. These data suggest the possible involvement of MEK1/2 MAPK in the inhibitory effect of TPA on ASNS mRNA expression and that the induction of the down-regulation of ASNS (via MEK1/2 activation) may be a new strategy for the treatment of leukemia blast cells.