The prognosis of AML patients with chemotherapy is poor, especially those who are insensitive to and resistant to chemotherapy drugs. To clarify the underlying pathogenesis of AML and provide new therapeutic targets for clinical treatment, we explore the role of circRNA in leukemia.

High-throughput circRNA sequencing analysis was performed in patients with leukemia and healthy donors. RT-qPCR and western blot analysis were used to determine expression of GSK3β. RNA pull-down assay was used to detect miRNAs pulled down by hsa_circ_0121582. RNA immunoprecipitation assay was performed to evaluate the binding capacity between TET1 and hsa_circ_0121582.

A new and highly stable circRNA was found, which was derived from the reverse splicing of GSK3β exon 1 to exon 7, and hsa_circ_0121582 was down-regulated in leukemia cells. In gain-of-function experiments, the up-regulated hsa_circ_0121582 inhibited the proliferation of leukemia cells in vitro and in vivo. In the cytoplasm, hsa_circ_0121582 could act as a sponge for miR-224, attenuate the inhibiting effect of miR-224 on GSK3β, and thus up-regulate the expression level of GSK3β. In addition, hsa_circ_0121582 could bind to GSK3β promoter in the nucleus, and recruit DNA demethylase TET1 to ensuring the transcription of GSK3β. The upregulated GSK3β inhibited the Wnt/β-catenin signaling pathway, and reduced the aggregation of β-catenin in the nucleus, thus inhibited the proliferation of leukemia cells.

This study found that hsa_circ_0121582 was involved in the inhibition of tumor proliferation, and the restoration of hsa_circ_0121582 could be an effective treatment strategy for patients with leukemia.