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Phenylbutyrate has been shown recently to induce fetal hemoglobin (HbF) production in patients with sickle cell anemia and beta thalassemia. We have now examined related aromatic fatty acids in order to define the range of active structures and identify plausible mechanisms of action. Structure-function analysis revealed that for effective stimulation of HbF in erythroid precursors: (1) the ideal length for the aliphatic side chain is four carbons; (2) oxygen or sulfur substitutions in the carboxylic chain are allowed, as evidenced by the equal or increased activity of phenoxypropionate, benzylthioglycolate, and benzyloxyacetate compared with phenylbutyrate; and (3) blocking the carboxylate group by conversion to the amide form greatly reduces potency. Molecular analysis indicated that the prototype agent, phenylbutyrate, increases HbF production through transcriptional activation of the gamma-globin gene. The latter contains a butyrate responsive promoter known to up-regulate transcription in the presence of short-chain fatty acids of three to five carbons. To determine whether stimulation of an element in this promoter by phenylbutyrate and its analogues might contribute to their mechanism of action, we used a transient expression system involving K562 erythroleukemia cells transfected with a luciferase reporter gene driven by the minimum gamma-globin promoter. Transcriptional activation in this experimental system correlated well with the capacity of an aromatic fatty acid to increase HbF production in erythroid precursors (r = 0.94). Our studies identify potent analogues of phenylbutyrate for the treatment of beta-chain hemoglobinopathies, and suggest that stimulation of a butyrate responsive promoter may be responsible for their activity.

Human leukaemic K562 cells can be induced in vitro to erythroid differentiation by a variety of chemical compounds, including haemin, butyric acid, 5-azacytidine, cytosine arabinoside, mithramycin and chromomycin, cisplatin and cisplatin analogues. Differentiation of K562 cells is associated with an increase of expression of embryo-fetal globin genes, such as the zeta-, epsilon- and gamma-globin genes. The K562 cell line has been proposed as a very useful in vitro model system to determine the therapeutic potential of new differentiating compounds as well as to study the molecular mechanism(s) regulating changes in the expression of embryonic and fetal human globin genes. Inducers of erythroid differentiation stimulating gamma-globin synthesis could be considered for possible use in the therapy of haematological diseases associated with a failure in the expression of normal beta-globin genes. We have analysed the effects of tallimustine and distamycin on cell growth and differentiation of K562 cells. The results demonstrated that tallimustine is a potent inducer, while distamycin is a weak inducer, of K562 cell erythroid differentiation. Erythroid differentiation was associated with an increase of accumulation of gamma-globin mRNA and of production of both haemoglobin (Hb) Gower 1 and Hb Portland. In addition, tallimustine-mediated erythroid induction occurred in the presence of activation of the apoptotic pathway. The reasons for proposing tallimustine as an inducer of gamma-globin gene expression are strongly sustained by the finding that this compound stimulates fetal haemoglobin production in human erythroid precursor cells from normal subjects.

Hemoglobin (Hb) disorders are common, potentially lethal monogenic diseases, posing a global health challenge. With worldwide migration and intermixing of carriers, demanding flexible health planning and patient care, hemoglobinopathies may serve as a paradigm for the use of electronic infrastructure tools in the collection of data, the dissemination of knowledge, the harmonization of treatment, and the coordination of research and preventive programs. ITHANET, a network covering thalassemias and other hemoglobinopathies, comprises 26 organizations from 16 countries, including non-European countries of origin for these diseases (Egypt, Israel, Lebanon, Tunisia and Turkey). Using electronic infrastructure tools, ITHANET aims to strengthen cross-border communication and data transfer, cooperative research and treatment of thalassemia, and to improve support and information of those affected by hemoglobinopathies. Moreover, the consortium has established the ITHANET Portal, a novel web-based instrument for the dissemination of information on hemoglobinopathies to researchers, clinicians and patients. The ITHANET Portal is a growing public resource, providing forums for discussion and research coordination, and giving access to courses and databases organized by ITHANET partners. Already a popular repository for diagnostic protocols and news related to hemoglobinopathies, the ITHANET Portal also provides a searchable, extendable database of thalassemia mutations and associated background information. The experience of ITHANET is exemplary for a consortium bringing together disparate organizations from heterogeneous partner countries to face a common health challenge. The ITHANET Portal as a web-based tool born out of this experience amends some of the problems encountered and facilitates education and international exchange of data and expertise for hemoglobinopathies. Copyright © Informa Healthcare USA, Inc.

The aim of the present study was to determine whether angelicin is able to increase the expression of gamma-globin genes in human erythroid cells. Angelicin is structurally related to psoralens, a well-known chemical class of photosensitizers used for their antiproliferative activity in treatment of different skin diseases (i.e., psoriasis and vitiligo). To verify the activity of angelicin, we employed two experimental cell systems, the human leukemic K562 cell line and the two-phase liquid culture of human erythroid progenitors isolated from normal donors. The results of our investigation suggest that angelicin, compared with cytosine arabinoside, mithramycin and cisplatin, is a powerful inducer of erythroid differentiation and gamma-globin mRNA accumulation of human leukemia K562 cells. In addition, when normal human erythroid precursors were cultured in the presence of angelicin, increases of gamma-globin mRNA accumulation and fetal hemoglobin (HbF) production, even higher than those obtained using hydroxyurea, were detected. These results could have practical relevance, as pharmacologically-mediated regulation of the expression of human gamma-globin genes, leading to HbF induction, is considered a potential therapeutic approach in hematological disorders, including beta-thalassemia and sickle cell anemia.