Effects of anti-oxidants on normal and leukemic hematopoiesis

Abstract

Abstract Various compounds affecting oxidation status such as nitric oxide (NO), flavones, and flavonoids have been reported to have antiproliferative and specifically, antileukemic effects. We have examined the effects of NO donors and inhibitors as well as that of quercetin and flavopiridol on myeloid leukemic cells. The NO donor SNAP decreased both proliferation and viability of AML cell lines and primary blasts from AML patients. With leukemic cell lines KG1, KG1a, THP-1, and U937, quercetin decreased the growth and viability in a dose-dependent manner. As early as 4 to 6 hours, quercetin also increased expression on Annexin V in both these cell lines. Flavopiridol also decreased proliferation and viability of each of these cell lines. With fresh myeloid leukemic cells, quercetin and flavopiridol both decreased the viability and proliferation of blast cells in vitro. Wide sample to sample variation was noted, and the inhibitory effects were noted both in the presence and absence of exogenous growth factors. The percentage of cells undergoing apoptosis was higher in the absence of growth factor at all time points, and the effects of flavopiridol on apoptosis induction were more pronounced in the absence of growth factors. Apoptosis with flavopiridol was correlated with activated caspase-3 expression. In order to determine the effect of flavopiridol and quercetin on normal CD34+ cells, cells isolated from marrow of normal donors via a MiniMACS (Miltenyi) CD34+ cell isolation procedure were cultured in 1- to 100 μm flavopiridol or quercetin. Inhibitory effects of both quercetin and flavopiridol were seen at 48 to 72 hours of culture. While the flavonoids, quercetin and flavopiridol and the NO donor, SNAP, have anti-leukemic effects on leukemic cell lines and leukemic blasts and progenitors in culture, they also appear to be inhibitory to normal multipotential hematopoietic cells and clonogenic progenitors. Use of these agents either ex vivo or in future clinical trials would ideally require further exploitation of differential sensitivity of leukemic and normal progenitors to such agents.