Erythroid progenitor proliferation is stimulated by phenoxyacetic and phenylalkyl acids.

Short-chain fatty acids, such as butyrate and propionate, are under investigation as therapeutic stimulants of fetal hemoglobin production in the beta-hemoglobin disorders. Significant limitations to these fatty acids and derivatives as optimal therapeutics are their rapid metabolism in vivo and their induction of cell growth arrest in the G1 phase of the cell cycle. This antiproliferative activity is related to their inhibition of metabolic transport pumps which are essential for cell proliferation. Other small carbon compounds, the phenylalkyl acids, phenoxyacetic acids, and phenylacetic acids, which are structurally resistant to oxidative metabolism, are shown here to induce fetal globin production in human erythroid cultures at concentrations of 0.2 mM, lower than those required for most other fatty acids. Certain of these compounds were found not to inhibit cellular neutral amino acid transport function in erythroid cells, nor to inhibit erythroid colony (Bfu-e) growth. Certain of these compounds even stimulated human Bfu-e proliferation in vitro beyond that induced by optimal concentrations of hematopoietic growth factors. The combination of increased fetal globin chain production by these compounds and their stimulatory effects on erythropoiesis result in an increase in Hb F-expressing erythroid cells in culture several-fold greater than that achieved by the butyrates. These new compounds thus have the potential to provide superior therapy for the beta-hemoglobinopathies and other anemias.