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

Ethnopharmacological relevance: Astragalus 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 study: To investigate the effects of APS on the erythroid differentiation and the mechanism of action by microarray analysis in K562 cells. Materials and methods: Benzidine 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. Results: Of the 13.2% positive cells detected by benzidine staining, the induction was the highest with 200 mu g/ml APS on 72 h. G gamma-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 gamma-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. Conclusions: Our studies indicate that APS indicate potent activities on the erythroid differentiation by modulating genes of LMO2, Klf1, Klf3, Runx1, EphB4 and Sp1, increasing gamma-globin mRNA expression and fetal hemoglobin synthesis in K562 cells. Crown Copyright (C) 2009 Published by Elsevier Ireland Ltd. All rights reserved.