Date of Award

January 2012

Document Type

Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Bernard Forget

Subject Area(s)

Medicine

Abstract

IDENTIFICATION OF NOVEL COMPOUNDS THAT INCREASE FETAL HEMOGLOBIN AND AMERIOLATE HEMOGLOBINOPATHIES. Jocelyn B. Chandler, Erica Esrick, Katherine Lin, and Benjamin L. Ebert. Division of Hematology, Department of Internal Medicine, Brigham & Women's Hospital, Harvard Medical School, Boston, MA. (Sponsored by Bernard Forget, Section of Hematology, Department of Medicine, Yale University School of Medicine).

Hemoglobinopathies, such as Sickle Cell Disease (SCD) and beta thalassemia, are characterized by mutation or decreased expression of the beta-globin gene. Current treatment options are relatively limited because effective drugs that can ameliorate these disorders have been difficult to identify. The only curative therapy, hematopoietic stem cell transplantation, has narrow applicability. SCD patients are generally managed with a combination of supportive care and hydroxyurea. Hydroxyurea works by increasing fetal hemoglobin to therapeutic levels, but this drug has moderate efficacy and high toxicity in many patients, thus limiting its clinical use.

Given the paucity of treatment options for hemoglobinopathies, this project focused on identifying drugs that could induce fetal hemoglobin based on our evolving understanding of globin gene regulation. We investigated inhibitors of two epigenetic modulators known as histone deacetylases (HDACs) and DNA methyltransferases (DNMTs). These potential therapeutic targets emerged from a high throughput small-molecule screen used to detect novel compounds that modulate globin gene expression levels in primary human erythroid cells. We previously demonstrated that inhibition of HDAC1 and HDAC2 increases gamma-globin relative to beta-globin mRNA expression by nearly 10-fold without affecting global gene expression. For this work, we used short hairpin RNAs to target three significant DNMT genes in our in vitro system and then employed quantitative RT-PCR to confirm effects on gene expression. We found that these shRNAs effectively knockdown their target genes, but do not increase gamma-globin gene expression. This study is an important first step in understanding therapeutics that affect globin gene regulation and offers a novel approach for future drug discovery efforts.

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