Silencing long non-coding RNA HOTAIR exerts anti-oncogenic effect on human acute myeloid leukemia via demethylation of HOXA5 by inhibiting Dnmt3b.

BACKGROUND: As an aggressive hematological malignancy, acute myeloid leukemia (AML) remains a dismal disease with poor prognosis. Long non-coding RNAs (lncRNAs) have been widely reported to be involved in tumorigenesis of AML. Here, we define an important role of lncRNA HOTAIR in AML in relation to HOXA5 methylation. METHODS: Firstly, the expression of HOTAIR was examined in AML samples and cells collected. Next, gain- or loss-of function experiments were conducted in AML cells to explore the effect of HOTAIR on AML. Then, relationship among HOXA5 promoter methylation, HOTAIR and Dnmt3b was measured. Expression of HOXA5 and cell proliferation/apoptosis-related genes was also detected. A last, in vivo assay was performed to assess the tumor formation in nude mice in order to explore the roles of HOTAIR and HOXA5 in cell apoptosis and proliferation. RESULTS: LncRNA HOTAIR was found to be upregulated in AML cells and tissues. With silencing of HOTAIR and overexpression of HOXA5, AML cell proliferation was decreased while the apoptosis was induced. Furthermore, HOTAIR was observed to recruit Dnmt3b and to increase HOXA5 promoter methylation. Moreover, silencing HOTAIR and upregulating HOXA5 were found to induce apoptosis and reduce proliferation of AML cells in vivo. CONCLUSION: Our findings highlight the anti-tumor ability of HOTAIR silencing in AML, suggesting that silencing HOTAIR was able to inhibit AML progression through HOXA5 promoter demethylation by decreasing Dnmt3b.

[KMT2A Activates Akt/mTOR Signaling Pathway Through LncRNA-HOTAIR to Influence the Biological Behavior of AML Cells].

OBJECTIVE: To investigate the expression of lysine methyltransferase 2A (KMT2A) in acute myeloid leukemia (AML) cells and its molecular mechanism affecting the proliferation of AML cells. METHODS: Co-immunoprecipitation assay was used to detect the binding of KMT2A to long non-coding RNA-HOX transcript antisense RNA (lncRNA-HOTAIR). AML cell proliferation was detected by 5-ethynyl-2'-deoxyuridine (EdU) assay. RESULTS: The PCR amplification signal of KMT2A group was significantly stronger than that of the negative control group and IgG group (P<0.01). Compared with the negative control group and KMT2A-OE + lncRNA-HOTAIR-KD group, the ratio of EdU+ cells in both KMT2A-OE group and lncRNA-HOTAIR-OE group significantly increased (P<0.01). Compared with negative control group, the ratio of EDU+ cells in KMT2A-KD group and lncRNA-HOTAIR-KD group significantly decreased (P<0.01), the expression levels of p-Akt and p-mTOR in both KMT2A-OE group and lncRNA-HOTAIR-OE group significantly increased (P<0.01). CONCLUSION: KMT2A can interact with lncRNA-HOTAIR to promote the activation of Akt/mTOR signaling pathway, thus promoting the proliferation of AML cells.

Polymorphisms in ERCC1 and susceptibility to childhood acute lymphoblastic leukemia in a Chinese population.

Excision repair cross-complementation group 1 (ERCC1) is important in repairing DNA damage and genomic instability, and polymorphisms in ERCC1 may play a role in human tumors. In this study, the relationship of two ERCC1 polymorphisms, 8092C>A and 19007G>A, with susceptibility to acute lymphoblastic leukemia (ALL) was investigated in 183 childhood patients. For the ERCC1 8092C>A polymorphism, individuals carrying the ERCC1 8092CC genotype had a significantly higher risk when compared with those carrying at least one A allele gene (AA/AC). Analysis after stratification for sex showed that the males carrying ERCC1 8092CC genotype were associated with highly significant increased risk of ALL (1.94-fold) but not females. There was no association between ERCC1 19007G>A polymorphism and ALL risk when all patients as a group were analyzed. However, the males carrying ERCC119007A allele were associated with highly significant increased risk of ALL (2.36-fold). For the ERCC1 8092C>A polymorphism, individuals under 8 years old (median age) carrying CC genotype had significantly higher risk. However, the 19007G>A polymorphism was not associated with such age-related ALL risk. These results suggest that the ERCC1 8092C>A polymorphism may be related to the occurrence of childhood ALL in a Chinese population.

miR-150 exerts antileukemia activity in vitro and in vivo through regulating genes in multiple pathways.

MicroRNAs, a class of small noncoding RNAs, have been implicated to regulate gene expression in virtually all important biological processes. Although accumulating evidence demonstrates that miR-150, an important regulator in hematopoiesis, is deregulated in various types of hematopoietic malignancies, the precise mechanisms of miR-150 action are largely unknown. In this study, we found that miR-150 is downregulated in samples from patients with acute lymphoblastic leukemia, acute myeloid leukemia, and chronic myeloid leukemia, and normalized after patients achieved complete remission. Restoration of miR-150 markedly inhibited growth and induced apoptosis of leukemia cells, and reduced tumorigenicity in a xenograft leukemia murine model. Microarray analysis identified multiple novel targets of miR-150, which were validated by quantitative real-time PCR and luciferase reporter assay. Gene ontology and pathway analysis illustrated potential roles of these targets in small-molecule metabolism, transcriptional regulation, RNA metabolism, proteoglycan synthesis in cancer, mTOR signaling pathway, or Wnt signaling pathway. Interestingly, knockdown one of four miR-150 targets (EIF4B, FOXO4B, PRKCA, and TET3) showed an antileukemia activity similar to that of miR-150 restoration. Collectively, our study demonstrates that miR-150 functions as a tumor suppressor through multiple mechanisms in human leukemia and provides a rationale for utilizing miR-150 as a novel therapeutic agent for leukemia treatment.

Impaired therapeutic vasculogenesis by transplantation of OxLDL-treated endothelial progenitor cells.

Previous in vitro studies have revealed that oxidized low density lipoprotein (OxLDL) has negative effects on the proliferation and activity of endothelial progenitor cells (EPCs). Here, we evaluated the effect of OxLDL on the therapeutic potential of EPCs in ischemia-induced neovascularization. EPCs derived from mobilized human peripheral blood mononuclear cells were cultured without or with OxLDL before transplantation. Hindlimb ischemia models were surgically induced in athymic nude mice, which then received an intracardiac injection of 3 x 10(5) EPCs. By laser Doppler perfusion image and ischemia damage score, we found that blood perfusion and ischemia damage were less well recovered in the OxLDL-treated EPC transplantation group than in controls. Histological examination showed fewer transplanted EPCs and lower capillary density in ischemic tissue. Local delivery of Stromal cell-derived factor (SDF-1) restored this defect and improved blood perfusion by recruiting OxLDL-treated EPCs to the ischemic area and increasing host capillary density. These results provide for the first time direct evidence that OxLDL impaired the therapeutic potential of EPCs in ischemia-induced neovascularization through an inhibitory effect on the migration, adhesion, and incorporation of EPCs into vasculature and/or entrapment in the perivascular region in vivo. A therapeutic strategy based on SDF-1 administration ameliorated such defects and improved postischemic neovascularization.