en 24523956 Background: The major hemoglobin in the fetus is hemoglobin F (𝛼2𝛾2), whereas in adult humans, hemoglobin A (𝛼2𝛽2) is predominately expressed. Several studies have indicated that expression of the HbF subunit 𝛾-globin might be regulated post-transcriptionally. This could be done by small non-coding RNAs called microRNAs which target mRNAs in a sequence-specific manner and lead to translational repression or mRNA decay. The aim of this study is to evaluate the effect of miR-26b up-regulation on 𝛾-globin gene expression in K-562 cell line. Methods: These cells were grown in RPMI 1640 and pre miR-26b and were transfected within K-562 cell line using lentiviral vector. After RNA extraction and cDNA synthesis in selected days, miRNA up-regulation was confirmed by miRNA real time PCR and then 𝛾and 𝛽chain and GATA-1 expression were investigated by RT and QRT-PCR. Results: The viability of cells before transfection was 90%. Three and 7 days after transfection, through the use of relative Q-PCR, the 𝛾 chain expression increased 3.7, 6.8 and 3.8 folds and GATA-1 expression increased 2.1, 6.0 and 8.0 in comparison with untransfected cells. Conclusion: The data suggest that miR-26b can be involved in the increase of 𝛾-globin gene expression in K-562 cell line. We suggest that miR-26b may be a significant therapeutic target for increasing HbF levels in patients with sickle cell disease and 𝛽-thalassemia. K-562, MicroRNAs, MiR-26b 53 56 https://www.ajmb.org/En/Article.aspx?id=142 https://www.ajmb.org/PDF/En/FullText/142.pdf SadeghAlijaniDepartment of Hematology, Allied Medical School, Tehran University of Medical Sciences, Tehran, Iran675ShabanAlizadehDepartment of Hematology, Allied Medical School, Tehran University of Medical Sciences, Tehran, Iran219AhmadKazemiDepartment of Hematology, Allied Medical School, Tehran University of Medical Sciences, Tehran, Iran677ZahraKashani KhatibStudents Scientific Research Center (SSRC), Allied Medical School, Tehran University of Medical Sciences, Tehran, Iran678MasoudSoleimaniDepartment of Hematology, Tarbiat Modares University, Tehran, Iran221MohamadrezaRezvaniDepartment of Hematology, Allied Medical School, Tehran University of Medical Sciences, Tehran, Iran680NedaMinayiDepartment of Hematology, Allied Medical School, Tehran University of Medical Sciences, Tehran, Iran681FarshidKaramiDepartment of Hematology, Allied Medical School, Tehran University of Medical Sciences, Tehran, Iran682BehnooshTayebiDepartment of Hematology, Qaem Hospital, Mashhad University of Medical Sciences, Mashhad, Iran683