Inhibitory effects of aclarubicin on nitric oxide production in aortic smooth muscle cells and macrophages

Abstract

The effects of aclarubicin (ACR), an anthracycline antibiotic, on inducible nitric oxide (NO) synthesis was investigated in rat aortic smooth muscle cells (RASMCs) and RAW macrophages. ACR at concentrations as low as 0.1 μM significantly inhibited NO production induced by interleukin-1β in RASMCs. About 5- to 10-fold higher concentrations of ACR were required for inhibition of interferon-γ and lipopolysaccharide-induced NO production in RAW cells. When ACR was subsequently administered to inducible NO synthase (iNOS) induction, the NO production was barely suppressed in RASMCs. Moreover, ACR (up to 10 μM) lacked direct inhibitory effects on iNOS activity in homogenates of these cells. ACR (0.1 μM) inhibited the expression of iNOS protein and mRNA in RASMCs without concomitant cytotoxic effects. ACR (>0.5 μM)-induced inhibition of NO production in RAW cells was associated with substantial cytotoxic effects as shown by measurement of lactate dehydrogenase release. These results suggest that ACR is a potent inhibitor of iNOS induction in vascular smooth muscle, but inhibits iNOS induction in macrophage only at high cytotoxic concentrations.