Sickle cell disease (SCD) is one of the most common inherited
hemoglobinopathy disorders that affects millions of people worldwide. Reactivation of HBG (HBG1, HBG2) gene expression and induction of
fetal hemoglobin (HbF) is an important therapeutic strategy for ameliorating the clinical symptoms and severity of SCD.
Hydroxyurea is the only US FDA-approved drug with proven efficacy to induce HbF in SCD patients, yet serious complications have been associated with its use. Over the last three decades, numerous additional pharmacological agents that reactivate HBG transcription in vitro have been investigated, but few have proceeded to FDA approval, with the exception of
arginine butyrate and
decitabine; however, neither drug met the requirements for routine clinical use due to difficulties with oral delivery and inability to achieve therapeutic levels. Thus, novel approaches that produce sufficient efficacy, specificity, and sustainable HbF induction with low adverse effects are desirable. More recently,
microRNAs (
miRNAs) have gained attention for their diagnostic and therapeutic potential to treat various diseases ranging from
cancer to
Alzheimer's disease via targeting oncogenes and their gene products. Thus, it is plausible that
miRNAs that target HBG regulatory genes may be useful for inducing HbF as a treatment for SCD. Our laboratory and others have documented the association of
miRNAs with HBG activation or suppression via silencing transcriptional repressors and activators, respectively, of HBG expression. Herein, we review progress made in understanding molecular mechanisms of
miRNA-mediated HBG regulation and discuss the extent to which molecular targets of HBG might be suitable prospects for development of SCD clinical
therapy. Lastly, we discuss challenges with the application of
miRNA delivery in vivo and provide potential strategies for overcoming barriers in the future.