MicroRNA‑223 overexpression suppresses protein kinase C ε expression in human leukemia stem cell‑like KG‑1a cells

MicroRNA‑223 (miR‑223) is dysregulated in various cancer types, including acute myeloid leukemia (AML). Despite this, there has been a lack of studies exploring the role of miR‑223 in leukemic stem cells, particularly those involved in drug resistance, a major cause of chemotherapy failure in AML. The present study aimed to elucidate the impact of miR‑223 on drug resistance in the leukemic stem‑cell line, KG‑1a. Two AML cell lines, KG‑1 and KG‑1a, differing in the proportion of CD34⁺CD38‑ cells, were assessed for doxorubicin (DOX) sensitivity using the Cell Counting Kit‑8 assay. The expression levels of miR‑223 and protein kinase C ε (PKCε) were evaluated via reverse transcription‑quantitative PCR and western blot analysis. The association between miR‑223 and its target, PKCε, was confirmed by luciferase activity assay. The effects of miR‑223 overexpression and PKCε inhibition were also evaluated in KG‑1a cells using miR‑223 mimic and small interfering (si)RNA transfection, respectively. Daunorubicin was then used to assess drug sensitivity in the siRNA‑transfected KG‑1a cells. Compared with KG‑1 cells, KG‑1a cells displayed greater resistance to DOX, and had increased PKCε levels and decreased miR‑223 expression. Overexpression of miR‑223 led to PKCε protein downregulation in KG‑1a cells, which was further confirmed by a luciferase assay demonstrating miR‑223 targeting of PKCε. However, despite these effects, miR‑223 overexpression and PKCε inhibition did not change drug sensitivity in KG‑1a cells compared with negative control cells. In summary, the present study demonstrated that miR‑223 could target and silence PKCε expression in KG‑1a cells; however, the chemoresistance of KG‑1a cells to anthracycline drugs may not be directly associated with the low expression of miR‑223.