PML/RARa blocks the differentiation and promotes the proliferation of acute promyelocytic leukemia through activating MYB expression by transcriptional and epigenetic regulation mechanisms.

The promyelocytic leukemia (PML)/retinoic acid receptor-alpha (RARα) onco-fusion protein that is generated from t(15;17) chromosome translocation is crucial for the leukemogenesis of acute promyelocytic leukemia (APL) and is well documented as a transcriptional repressor. To understand the relationship between PML/RARα and the oncogene in the development of APL, we investigate the regulation mechanism of PML/RARα to MYB proto-oncogene and the role of this regulation on the proliferation and differentiation of APL cells. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) assays show that MYB expression was significantly higher in PML/RARα positive cell lines. Microarray data verify that the MYB expression was significantly higher in APL patient samples than in normal promyelocyte samples. Further expression analysis from RT-qPCR and microarray data verifies that the expression of MYB is upregulated by PML/RARα. Transcriptional factor binding analysis shows that MYB is directly bound by PML/RARα and its cofactors. Luciferase assays show that PML/RARα transactivated MYB promoter activity through the RARα binding site and the coexistence of CCAAT enhancer binding protein ε. We also find that PML/RARα increases the acetylation level of the promoter region of MYB. Further evidence demonstrates that PML/RARα regulates MYB expression through long-range interaction. Functionally, PML/RARα increases the cell proliferation and blocks the differentiation through activating MYB expression. Collectively, this study uncovers a novel mechanism of PML/RARα-mediated transcriptional activation and enriches our knowledge of the onco-fusion protein-mediated transcription activation.

AML1/ETO trans-activates c-KIT expression through the long range interaction between promoter and intronic enhancer.

The AML1/ETO onco-fusion protein is crucial for the genesis of t(8;21) acute myeloid leukemia (AML) and is well documented as a transcriptional repressor through dominant-negative effect. However, little is known about the transactivation mechanism of AML1/ETO. Through large cohort of patient's expression level data analysis and a series of experimental validation, we report here that AML1/ETO transactivates c-KIT expression through directly binding to and mediating the long-range interaction between the promoter and intronic enhancer regions of c-KIT. Gene expression analyses verify that c-KIT expression is significantly high in t(8;21) AML. Further ChIP-seq analysis and motif scanning identify two regulatory regions located in the promoter and intronic enhancer region of c-KIT, respectively. Both regions are enriched by co-factors of AML1/ETO, such as AML1, CEBPe, c-Jun, and c-Fos. Further luciferase reporter assays show that AML1/ETO trans-activates c-KIT promoter activity through directly recognizing the AML1 motif and the co-existence of co-factors. The induction of c-KIT promoter activity is reinforced with the existence of intronic enhancer region. Furthermore, ChIP-3C-qPCR assays verify that AML1/ETO mediates the formation of DNA-looping between the c-KIT promoter and intronic enhancer region through the long-range interaction. Collectively, our data uncover a novel transcriptional activity mechanism of AML1/ETO and enrich our knowledge of the onco-fusion protein mediated transcription regulation.

c-Myc, RMRP, and miR-34a-5p form a positive-feedback loop to regulate cell proliferation and apoptosis in multiple myeloma.

Long non-coding RNA (lncRNA) component of mitochondrial RNA processing endoribonuclease (RMRP) has been demonstrated to be implicated in human cancer processes. However, the role of lncRNA RMRP in multiple myeloma (MM) remains unknown. In this paper, we proved that RMRP and c-Myc were upregulated, while miR-34a-5p was downregulated in MM cell lines and bone marrows of MM patients. High RMRP expression significantly correlated with worse disease-free survival and overall survival in MM patients. c-Myc promoted RMRP transcription by directly binding to its promoter region. Knockdown of RMRP inhibited proliferation and promoted apoptosis of OPM2 and RPMI-8226 cells. Negative correlation between RMRP, and miR-34a-5p was discovered in bone marrows of MM patients. c-Myc expression was inversely correlated with miR-34a-5p in bone marrows of MM patients. Additionally, silencing of RMRP led to a marked reduction in c-Myc expression in OPM2 and RPMI-8226 cells, and this action was obviously blocked by miR-34a-5p knockdown. Moreover, upregulation of miR-34a-5p repressed proliferation and promoted apoptosis of OPM2 and RPMI-8226 cells. However, RMRP overexpression blocked these changes triggered by miR-34a-5p mimic. Besides, RMRP knockdown repressed MM tumor growth in vivo. Conclusions, RMRP functions as a miR-34a-5p sponge to promote cell proliferation and repress cell apoptosis through upregulation of c-Myc in MM.

[Effect of SHIP-1 on Invasion, Migration and PI3K-AKT Signaling Pathway of Leukemic Cells].

OBJECTIVE: To investigate the effect of SH2-containing inositol phosphatase-1 (SHIP-1) on the proliferation, invasion and migration of human leukemia cells as well as phosphatidylinositol-3 kinase (PI3K) / protein kinase B (AKT) signaling pathway. METHODS: The overexpression vector pCDNA3.1-SHIP1 was transfected into THP-1 cells by Lipofectamine 2000. The experiment was divided into 3 groups: control group (untreated cells) and empty vector group (transfected with empty vector pCDNA3.1-NC) and overexpression group (transfected with overexpression vector pCDNA3.1-SHIP1). The cell proliferation was tected by CCK-8 assay, Transwell assay was used to evaluate the cell invasion and migration capabilities. The expressions of SHIP-1, AKT, phosphorylated AKT (pAKT), matrix metalloproteinase-9 (MMP-9) protein were analyzed by Western blot. RESULTS: The expression of SHIP-1 in overexpression group was significantly higher than that in the control group(P<0.05). Compared with the control group, the absorbance of the cells in the empty vector group was not statistically different (P>0.05), and the absorbance in overexpression group decreased significantly(P<0.05). The cell numbers of invasion and migration were not significantly different between empty and control groups(P>0.05), but those in overexpression group were significantly lower than those in the control group(P<0.05). Compared with the control group, the expression of AKT, pAKT and MMP-9 in the empty vector group was not statistically different (P>0.05); the AKT protein in overexpression group was not significantly different (P>0.05), but the pAKT and MMP-9 significantly decreased(P<0.05). CONCLUSION: SHIP-1 plays a role in inhibiting the proliferation, invasion and migration of leukemia cells, the mechanism probably relates with supressing the expression of MMP-9 by regulating PI3K/AKT signaling pathway.

LncRNA MALAT1 acts as an oncogene in multiple myeloma through sponging miR-509-5p to modulate FOXP1 expression.

Previous studies showed that Metastasis associated lung adenocarcinoma transcript 1(MALAT1) acted as an oncogene in Multiple Myeloma (MM). However, the underlying mechanism of MALAT1 in MM remains unclear. Quantitative real time-PCR(qRT-PCR) was used to determine MALAT1 expression in MM samples and cell lines. in vitro function assays were used to determine the function of MALAT1 on MM cells. Bioinformatics tools were used to predict the targets of MALAT1 and miR-509-5p, respectively. Furthermore, rescue experiments were performed to further confirm the regulation of miR-509-5p by MALAT1. In the present study, our data showed that MALAT1 expression was upregulated in MM samples and cell lines. In function assays, we confirmed that MALAT1 inhibition significantly suppressed cells proliferation, induced cells apoptosis, arrested cells in G1/S phase, and inhibited MM cells growth in vivo. Furthermore, MALAT1 was identified to function as a competitive endogenous RNA (ceRNA) for miR-509-5p to promote MM cell viability. Additionally, our results suggested that miR-509-5p targeted the 3'-UTR of FOXP1 to suppress MM cells progression. Meanwhile, our results showed that miR-509-5p inhibitors significantly abrogated the decreased expression of FOXP1 induced by MALAT1 suppression, indicating that MALAT1 could positively regulate FOXP1 expression by sponging miR-509-5p. Our findings suggested that MALAT1/miR-509-5p/FOXP1 axis was one of the key signalings in mediating MM cell growth, and further indicated that MALAT1 could act as a novel diagnostic marker and therapeutic target for the treatment of MM.

[Effects of Different Dosages of rhG-CSF on Duration of Aleucocytosis and Leukocytes Level after Chemotherapy of Patients with Hematologic Malignancies].

OBJECTIVE: To compare the effects of different dosages of rhG-CSF on duration of aleucocytosis and white blood cell counts after chemotherapy of patients with hematologic malignancies. METHODS: Ninety patients in our hospital from December 2011 to June 2016 were chosen as study objects, and all of them were divided into 3 groups: group A (rhG-CSF 200 µg/m2), group B(rhG-CSF 300 µg/m2) and group C(rhG-CSF 400 µg/m2); 30 patients from January 2004 to January 2007 were chosen as control(control group). The WBC(min) and its duration, WBC(max) and its timepoint were compared among different groups. The infection rate, incidence of side reactions and total amount of rhG-CSF used in different groups were compared. RESULTS: In control group, WBC(min) was(1.30±0.11)×109/L, its duration was (3.2±0.7)d, WBC(max) was(5.14±0.41)×109/L, and its time point was (26.1±1.8)d; these in group A were (3.14±0.23)×109/L,(2.7±1.0)d, (10.08±0.69)×109/L and (14.9±1.8)d respectively; these in group B were (3.11±0.32)×109/L, (0.9±0.5)d, (10.17±0.75)×109/L and(10.7±1.5)d respectively; these in group C were (3.15±0.30)×109/L,(0.5±0.3)d, (11.95±0.86)×109/L and (10.6±1.5)d, respectively. Compared with control group, the WBC(min) and WBC(max) were both increased significantly, the duration of WBC(min) was shortened and the timepoint of WBC(max) was moved up(P<0.05). The infection rate of group C (3.33%(1/30)) was significantly lower than that of control group(33.33%(10/30))(P<0.05), total used amount of rhG-CSF and incidence of side reactions were not statistically different among group A,B,C(P>0.05). CONCLUSION: Compared with low dosage of rhG-CSF, medium/high dosage of rhG-CSF can help to shorten duration of a leukocytosis after chemotherapy of patients.

[Change of Plasma Interleukin-16 Level in Patients with Multiple Myeloma and Its Clinical Significance].

OBJECTIVE: To investigate the change of plasma IL-16 level in patients with multiple myeloma(MM) and its clinical significance. METHODS: Sixty-two patients with multiple myeloma were admitted in our hospital from June 2008 to June 2015. Forty healthy volunteers were selected as control group. The peripheral blood of all the patients and healthy volunteers were collected before the treatment of patients. The levels of IL-16, Cys-C, LDH and ß2-MG were measured. ROC curve was used to analyze the optimal IL-16 thresholds in MM patients. Kaplan-Meier method was used to analyze the factors affecting overall survival. RESULTS: The levels of IL-16, Cys-C, LDH and ß2-MG in the MM group were significantly higher than those in the control group (P<0.05). The levels of IL-16, Cys-C, LDH and ß2-MG in patients with different ISS were significantly different (P<0.05). The levels of IL-16, Cys-C, LDH and ß2-MG in ISS III groups were higher than those in ISS I and ISS II groups(P<0.05). When the IL-16 concentration was 171.26 ng/L, the AUC was 0.787 (P<0.01), and the sensitivity and specificity were 82.25% and 75.80%, respectively, when the IL-16 threshold was predicted by ROC curve analysis. The 3-year overall survival rates of patients with IL-16≤171.26 ng/L and IL-16>171.26 ng/L were 91.93% and 51.61%, respectively (P<0.01). Multivariate analysis showed that the changes of IL-16 levels were significantly related with overall survival (P<0.01). CONCLUSION: The level of IL-16 in peripheral blood of patients with multiple myeloma has been cofirmed to be significantly elevated, and the elevated IL-16 is closely related with the prognosis.

miR-92a Inhibits Proliferation and Induces Apoptosis by Regulating Methylenetetrahydrofolate Dehydrogenase 2 (MTHFD2) Expression in Acute Myeloid Leukemia.

Aberrant expression of microRNA-92a (miR-92a) has been investigated in various cancers. However, the function and mechanism of miR-92a in acute myeloid leukemia (AML) remain to be elucidated. Our data showed that miR-92a was evidently downregulated and methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) was remarkably upregulated in AML cell lines HL-60 and THP-1. Dual luciferase reporter assay revealed that MTHFD2 was a direct target of miR-92a. Gain- and loss-of-function analysis demonstrated that MTHFD2 knockdown or miR-92a overexpression notably inhibited proliferation and promoted apoptosis of AML cell lines. Restoration of MTHFD2 expression reversed proliferation inhibition and apoptosis induction of AML cells triggered by miR-92a. Moreover, an implanted tumor model in mice indicated that miR-92a overexpression dramatically decreased tumor growth and MTHFD2 expression in vivo. Taken together, our results suggest that miR-92a inhibits proliferation and induces apoptosis by directly regulating MTHFD2 expression in AML. miR-92a may act as a tumor suppressor in AML, providing a promising therapeutic target for AML patients.