Tianjin Medical Journal ›› 2026, Vol. 54 ›› Issue (3): 225-231.doi: 10.11958/20252591

• Cell and Molecular Biology •     Next Articles

Let-7b inhibits the development of AML through inducing repolarization of leukemia-associated macrophages

JIANG Tianyou(), LI Min, SUN Biwen, LI Yueyang, XING Lijing, TIAN Chen()   

  1. Department of Hematology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin’s Clinical Research Center for Cancer, Tianjin 300060, China
  • Received:2025-07-25 Revised:2025-11-10 Published:2026-03-15 Online:2026-03-17
  • Contact: E-mail:tianchen@tjmuch.com

Abstract:

Objective To study the mechanism of let-7b regulating acute myeloid leukemia (AML) by leukemia-associated macrophages (LAMs). Methods Bone marrow cells were collected from AML patients prior to any treatment and cryopreserved. Patients subsequently received induction chemotherapy with the "DA 3+7" regimen, and therapeutic responses were evaluated post-treatment. According to the efficacy assessment results, patients were stratified into two groups: the complete remission (CR) group and the non-complete remission (refractory) group. AML blasts of pre-cryopreserved patients were then respectively transplanted into NOD/SCID mice to establish AML xenograft mouse model corresponding to the CR group and the refractory group. After miRNA sequencing and polymerase chain reaction (PCR) verification, let-7b was selected as the target gene to investigate its role in MLL-AF9-induced AML. Transfection of LAMs in MLL-AF9-induced AML mice with let-7b shRNA or scramble control was validated by quantitative real-time PCR (RT-qPCR), Western blot assay and enzyme-linked immunosorbent assay (ELISA) in vitro and in vivo experiments. Results Compared with the AML CR group, the apoptosis rate of LAM cells was lower in the AML refractory group. Furthermore, let‐7b was a potentially aberrant gene in LAMs contributing to M2‐subtype characteristics. Knockdown of let‐7b in LAMs could inhibit the development of AML by repolarizing LAMs toward M1‐subtype characteristics through the activation of Toll‐like receptor and NF‐κB pathway. The results of in vivo experiments showed that knockdown of let-7b in LAMs inhibited the proliferation of leukemia cells and decreased infiltration into spleen, thereby inhibiting the progression of AML. Conclusion Let-7b interference in LAMs can activate Toll-like receptors (TLRs) and NF-κB pathway, promote the repolarization of LAMs to M1 macrophages, thereby inhibiting the development of AML.

Key words: leukemia, myeloid, acute, tumor-associated macrophages, NF-kappa B, Toll-like receptors, let-7b, leukemia-associated macrophages

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