Gamma reactivation using the spongy effect of KLF1-binding site sequence: an approach in gene therapy for beta-thalassemia

Abstract

Objective(s): beta-thalassemia is one of the most common genetic disorders in the world. As one of the promising treatment strategies, fetal hemoglobin (Hb F) can be induced. The present study was an attempt to reactivate the gamma-globin gene by introducing a gene construct containing KLF1 binding sites to the K562 cell line. Materials and Methods: A plasmid containing a 192 bp sequence with two repeats of KLF1 binding sites on beta-globin and BCL11A promoters was constructed and used to transfect the K562 cell line. Positive selection was performed under treatment with 150 mu g/ml hygromycin B. The remaining cells were expanded and harvested on day 28, and genomic DNA was extracted. The PCR was carried out to verify insertion of DNA fragment to the genome of K562 cells. The cells were differentiated with 15 mu g/ml cisplatin. Flowcytometry was performed to identify erythroid differentiation by detection of CD235a+ cells. Real-time RT-PCR was performed to evaluate gamma-globin expression in the transfected cells. Results: A 1700 bp fragment was observed on agarose gel as expected and insertion of DNA fragment to the genome of K562 cells was verified. Totally, 84 of cells were differentiated. The transfected cells significantly increased gamma-globin expression after differentiation compared to untransfected ones. Conclusion: The findings demonstrate that the spongy effect of KLF1-binding site on BCL11A and beta-globin promoters can induce gamma-globin expression in K562 cells. This novel strategy can be promising for the treatment of gamma-thalassemia and sickle cell disease.