Effects of Astragalus polysaccharide on the erythroid lineage and microarray analysis in K562 cells

Ethnopharmacological relevanceAstragalus polysaccharide (APS), obtained from Astragalus membranaceus, displays a range of activities in many systems, including the promotion of immune responses, anti-inflammation, and the protection of vessels. It possesses potent pharmacological activity on differentiation to the erythroid lineage.Aim of the studyTo investigate the effects of APS on the erythroid differentiation and the mechanism of action by microarray analysis in K562 cells.Materials and methodsBenzidine staining, semi-quantitative RT-PCR, Western blot and microarray methods were used to survey the effects of APS on inducing erythroid differentiation and the changes of gene expression profile in K562 cells.ResultsOf the 13.2% positive cells detected by benzidine staining, the induction was the highest with 200 μg/ml APS on 72 h. Gγ-mRNA expression and fetal hemoglobin synthesis were significantly up-regulated. Microarray analysis showed that 31 genes were up-regulated and 108 genes were down-regulated. These differential expression genes generally regulate protein binding, cellular metabolic process, the cell proliferation, and transcriptional activator activity. The γ-globin gene was up-regulated, the genes related with erythroid differentiation such as LMO2, Runx1 and GTF2I were up-regulated, while Bklf, Eklf, EPHB4 and Sp1 were down-regulated.ConclusionsOur studies indicate that APS indicate potent activities on the erythroid differentiation by modulating genes of LMO2, Klf1, Klf3, Runx1, EphB4 and Sp1, increasing γ-globin mRNA expression and fetal hemoglobin synthesis in K562 cells.