MicroRNA-21 promotes proliferation in acute myeloid leukemia by targeting Krüppel-like factor 5

The roles and regulation of the KLF5 transcription factor in cancers

Krüppel‐like factor 5 (KLF5) is a member of the KLF family. Recent studies have suggested that KLF5 regulates the expression of a large number of new target genes and participates in diverse cellular functions, such as stemness, proliferation, apoptosis, autophagy, and migration. In response to multiple signaling pathways, various transcriptional modulation and posttranslational modifications affect the expression level and activity of KLF5. Several transgenic mouse models have revealed the physiological and pathological functions of KLF5 in different cancers. Studies of KLF5 will provide prognostic biomarkers, therapeutic targets, and potential drugs for cancers.

miR-21-5p promotes cell proliferation by targeting BCL11B in Thp-1 cells

Acute myeloid leukemia (AML) is a highly heterogeneous disease that remains untreatable. MicroRNAs (miRNAs or miRs) play important roles in the pathogenesis of leukemia. miR-21 is highly expressed in multiple types of human cancer and displays oncogenic activities; however, the clinical significance of miR-21 in AML remains unclear. In the present study, it was demonstrated that miR-21 levels were high in patients with AML and in AML cell lines. Further experiments demonstrated that overexpression of miR-21 in Thp-1 human monocytes derived from acute mononuclear leukemia peripheral blood promoted cell proliferation, while downregulation of miR-21-5p, a mature sequence derived from the 5' end of the miR-21 stem-loop precursor (another mature sequence, miR-21-3p, is derived form 3' end of miR-21), inhibited cell proliferation. Specifically, it was observed that overexpression of miR-21 could promote the transition of Thp-1 cells into the S and G2/M phases of the cell cycle, as shown by flow cytometry. Furthermore, inhibition of miR-21-5p arrested cells in the S and G2/M phases. Finally, BCL11B was determined to be a functional target of miR-21-5p by luciferase assays. Our study revealed functional and mechanistic associations between miR-21 and BCL11B in Thp-1 cells, which could serve to guide clinical treatment of AML.

Impact of Bone Marrow miR-21 Expression on Acute Myeloid Leukemia T Lymphocyte Fragility and Dysfunction

BACKGROUND

Acute myeloid leukemia (AML) is a hematopoietic malignancy in which antitumor immunity is impaired. The therapeutic management of AML requires understanding the mechanisms involved in the fragility and immune dysfunction of AML T lymphocytes.

METHODS

In this study, T lymphocytes from healthy donors (HD) and AML patients were used. Extracellular vesicles (EVs) from leukemic cells were screened for their microRNA content and impact on T lymphocytes. Flow cytometry, transcriptomic as well as lentiviral transduction techniques were used to carry out the research.

RESULTS

We observed increased cell death of T lymphocytes from AML patients. EVs from leukemia myeloid cell lines harbored several miRNAs, including miR-21, and were able to induce T lymphocyte death. Compared to that in HD, miR-21 was overexpressed in both the bone marrow fluid and infiltrating T lymphocytes of AML patients. MiR-21 induces T lymphocyte cell death by upregulating proapoptotic gene expression. It also increases the immunosuppressive profile of T lymphocytes by upregulating the IL13, IL4, IL10, and FoxP3 genes.

CONCLUSIONS

Our results demonstrate that miR-21 plays a significant role in AML T lymphocyte dysfunction and apoptosis. Targeting miR-21 may be a novel approach to restore the efficacy of the immune response against AML.

EZH2 dysregulation: Potential biomarkers predicting prognosis and guiding treatment choice in acute myeloid leukaemia

Accumulating studies have proved EZH2 dysregulation mediated by mutation and expression in diverse human cancers including AML. However, the expression pattern of EZH2 remains controversial in acute myeloid leukaemia (AML). EZH1/2 expression and mutation were analysed in 200 patients with AML. EZH2 expression was significantly decreased in AML patients compared with normal controls but not for EZH1 expression. EZH2 mutation was identified three of the 200 AML patients (1.5%, 3/200), whereas none of the patients harboured EZH1 mutation (0%, 0/200). EZH2 expression and mutation were significantly associated with -7/del(7) karyotypes. Moreover, lower EZH2 expression was associated with older age, higher white blood cells, NPM1 mutation, CEBPA wild-type and WT1 wild-type. Patients with EZH2 mutation showed shorter overall survival (OS) and leukaemia-free survival (LFS) than patients without EHZ2 mutation after receiving autologous or allogeneic haematopoietic stem cell transplantation (HSCT). However, EZH2 expression has no effect on OS and LFS of AML patients. Notably, in EZH2 low group, patients undergone HSCT had significantly better OS and LFS compared with patients only received chemotherapy, whereas no significant difference was found in OS and LFS between chemotherapy and HSCT patients in EZH2 high group. Collectively, EZH2 dysregulation caused by mutation and under-expression identifies specific subtypes of AML EZH2 dysregulation may be acted as potential biomarkers predicting prognosis and guiding the treatment choice between transplantation and chemotherapy.