[Construction and expression of the recombinant plasmid containing BddhFVIII in HepG2 cells].

OBJECTIVE: To get stable cell line expressing B domain-deleted human FVIII (BDDhFVIII) by constructing the eukaryotic expression plasmid. METHODS: Eukaryotic expression plasmid containing BDDhFVIII was constructed and transfected into HepG2 cells via electroporation. The expression and purification of the target protein was detected by Western blot. RESULTS: Results of enzyme digestion and sequence analysis demonstrated that the gene of BDDhFVIII was correctly inserted into the eukaryotic expression vector pcDNA4/v5-his. Western blot confirmed the successful expression of BDDhFVIII at the protein levels in HepG2 cells. CONCLUSION: The constructed eukaryotic expression vector was able to generate high level expression of human FVIII in HepG2 cells, thus could construct human blood coagulation FVIII stable cell line successfully.

[Expression of ADAR1 isoforms in murine acute T-ALL leukemia model].

This study was purposed to investigate the expression of ADAR1 isoforms of P110 and P150 during the development of murine leukemia. A Notch1 over-expressing murine T cell acute lymphoblastic leukemia model was used to study the expression of ADAR1. BMMNC were isolated at different stages of disease and CD45.2(+)GFP(+) leukemia cells were sorted by flow cytometry at late stage. The expression of ADAR1 was detected by real time quantitative PCR. The results showed that mouse bone marrow cells from both leukemia and control groups expressed P110 and P150. Difference of P110 and P150 mRNA expression were observed during the development of leukemia. The expression of P110 dramatically increased and was significantly higher than that in control group. However, the expression level of P150 in leukemia group decreased stably and reached one-fourth of that in control group at 14 day. Furthermore, similar expression patterns could be detected in sorted CD45.2(+)GFP(+) leukemia cells. It is concluded that the mRNA expressions of P110 and P150 show diverse patterns in the development of leukemia, suggesting that RNA editing mediated by ADAR1 isoforms may play different roles in leukemia.

Abnormal expression of ADAR1 isoforms in Chinese pediatric acute leukemias.

The posttranscriptional RNA editing by the type 1 adenosine deaminase acting on RNAs (ADAR1), expressed as p110 and p150 isoforms, is important for both physiological and pathological processes. Their expression and significance in leukemias remain unknown. Here, we investigated the expression of ADAR1 in Chinese pediatric acute leukemias by real-time PCR and Western blot. The results showed that significant high expression of p110 was detected in leukemias, especially in B-ALL, whereas a slight increase of p150 could be observed. Furthermore, the decrease of p110 expression was observed in B-ALL patients achieving complete remission. Moreover, among prognostic risk groups in ALL, the highest expressions of p110 and p150 were detected in standard-risk group, whereas their lowest expressions were in high-risk group. This observation was further confirmed in comparisons between good and poor prognostic groups based on prognostic related clinical features. These results demonstrated that ADAR1 isoforms showed different expression patterns, suggesting that they might play different roles in pediatric leukemias. Our results will help us for the better understanding of RNA editing, exploring the potential target for the treatment, and making prognostic evaluation in childhood leukemias.

The hyposensitive N187D P2X7 mutant promotes malignant progression in nude mice.

Nucleotides are new players in the intercellular communication network. P2X7 is a member of the P2X family of receptors, which are ATP-gated plasma membrane ion channels with diverse biological functions. Abnormal expression and dysfunction of P2X7 have been reported in leukemias. Here, we report a new P2X7 mutant (an A(559)-to-G substitution causing N187D P2X7) cloned from J6-1 leukemia cells. The characteristics of N187D P2X7 were studied by establishing stably transfected K562 cell lines. Our results show that N187D P2X7 required a higher concentration of agonist for its activation, leading to Ca(2+) influx (EC(50) = 293.3 ± 6.6 µm for the mutant and 93.6 ± 2.2 µm for wild-type P2X7) and ERK phosphorylation, which were not caused by differential cell-surface expression or related to high ATPase activity on the cell surface and in the extracellular space. K562 cells expressing this N187D mutant showed a proliferative advantage and reduced pro-apoptosis effects in vitro and in vivo. Furthermore, elevated angiogenesis and CD206-positive macrophage infiltration were found in tumor tissues formed by K562-M cells. In addition, higher expression of VEGF and MCP1 could be detected in tumor tissues formed by K562-M cells. Our results suggest that N187D P2X7, representing mutants hyposensitive to agonist, might be a positive regulator in the progression of hematopoietic malignancies.

Abnormal expression of P2X family receptors in Chinese pediatric acute leukemias.

Nucleotides are new players in intercellular communication network. P2X family receptors are ATP-gated plasma membrane ion channels with diverse biological functions. Their distribution patterns and significance in pediatric leukemias have not been established. Here we investigated the expression of P2X receptors in BMMC samples from Chinese pediatric acute leukemias. Real-time PCR and Western blot results showed that P2X1, P2X4, P2X5 and P2X7 receptors were simultaneously over expressed in leukemias compared with controls, whereas P2X2, P2X3 and P2X6 were absent or marginally expressed in both groups. It was worth noting that the co-expression feature of them, especially between P2X4 and P2X7, could be observed and the highest expression of P2X7 was detected in relapsed patients. Moreover, concomitant decrease of P2X4, P2X5 and P2X7 expressions was observed at CR stage in a follow-up study. Functional P2X7 was also verified. These results suggested that P2X1, P2X4, P2X5 and P2X7 were hematopoiesis-related P2X receptors, and their signaling, especially for P2X7, might play important roles in pediatric leukemias. P2X receptors might co-operatively contribute to the malignant phenotype in human pediatric leukemias.

A special linker between macrophage and hematopoietic malignant cells: membrane form of macrophage colony-stimulating factor.

The membrane form of macrophage colony-stimulating factor (mM-CSF) is an alternative splicing variant of this cytokine. Although its high expression was detected in hematopoietic malignancies, its physiologic and pathologic roles in hematopoietic system have not been established. In this report, stable transfectant clones expressing mM-CSF (Namalwa-M and Ramos-M) were obtained, which showed reduced proliferation potential in vitro. Moreover, the in vivo study showed that Namalwa-M and Ramos-M exhibited enhanced oncogenicity in tumor size in nude mice model, which could be inhibited by M-CSF monoclonal antibody. A remarkable increase in infiltrating macrophage and the vessel densities was found in tumor tissues formed by lymphoma cell lines that stably expressed mM-CSF, which suggested the involvement of macrophages in this process. The in vitro results using coculture system showed that macrophages could promote Namalwa-M and Ramos-M proliferation and activate extracellular signal-regulated kinase/mitogen-activated protein kinase signal pathway. In addition, the expression of murine origin vascular endothelial growth factor, basic fibroblast growth factor, and hepatocyte growth factor was elevated in Namalwa-M formed tumor tissues. These results suggested that mM-CSF should be a positive regulator in the development of hematopoietic malignancies by abnormally activating infiltrating macrophages, which in turn promote the malignant development. Thus, mM-CSF may be a critical linker between macrophages and malignant cells in the development of hematopoietic malignancies.