A multifunctional 5-aminolevulinic acid derivative induces erythroid differentiation of K562 human erythroleukemic cells

Anemia is a major clinical symptom of a wide variety of pathological conditions a common related to reduced erythropoiesis. Whereas erythropoietin treatment showed an improvement in the patients' condition, it revealed increased risks of thromboembolic and cardiovascular events. Herein we describe stimulation of erythropoiesis by the multifunctional 1-(butyryloxy)ethyl-5- amino-4-oxopentanoate, (AlaAcBu), a 5-aminolevulinic-acid (ALA) derivative, which undergoes metabolic hydrolysis yielding two erythroid differentiation inducers, ALA and butyric acid (BA), each acting through a different mechanism. ALA, the first precursor in the heme biosynthesis, accelerates heme synthesis and BA, a histone deacetylase inhibitor (HDACI) that activates the transcription of globin mRNA. Our results show that the AlaAcBu mutual prodrug is a potent chemical differentiation inducer of K562 human erythroleukemia cells manifested by augmentation of heme and globin synthesis and assembly of hemoglobin. Exposure of K-562 cells to AlaAcBu resulted in an increase in heme synthesis and globin expression. Stimulation of the heme pathway was evident by the over-expression of porphobilinogen deaminase (PBGD) and ferrochelatase. AlaAcBu promoted cellular erythroid differentiation depicted by the expression of the marker glycophorin A and cellular maturation characterized by cytoplasm hemoglobinization, polar arrangement of mitochondria and a developed central vacuolar system preceding nuclear extrusion. The ability of AlaAcBu to promote differentiation along the erythroid lineage and to dramatically induce hemoglobin synthesis presented in this report.