Downregulating CREBBP inhibits proliferation and cell cycle progression and induces daunorubicin resistance in leukemia cells.

Low expression levels of CREB­binding protein (CREBBP) have been demonstrated to be associated with high minimal residual disease at the end of induction therapy and adverse long­term outcomes in pediatric patients with acute lymphoblastic leukemia (ALL). However, the effect of low CREBBP expression on the prognosis of ALL has not yet been investigated. In the present study, CREBBP was downregulated and overexpressed in ALL cell lines (Jurkat and Reh). Sensitivity to chemotherapy and cell proliferation activity was determined via a Cell Counting Kit­8 assay. Cell cycle analysis was performed using flow cytometry. Immunofluorescence confocal microscopy and co­immunoprecipitation (Co­IP) assays were performed to determine the interaction between CREBBP and E2F transcription factor 3a (E2F3a). The binding of CREBBP to downstream gene caspase 8 associated protein 2 (CASP8AP2) promoters was assessed using a chromatin immunoprecipitation assay, and mRNA expression levels were detected via reverse transcription­quantitative PCR. Western blot analysis was performed to detect protein expression of CREBBP, E2F3a and CASP8AP2. Downregulation of CREBBP increased the IC50 value of daunorubicin; however, no significant affects were observed on the IC50 values of vincristine and L­asparaginase. Furthermore, downregulation of CREBBP notably inhibited leukemia cell proliferation, accumulated cells in the G0/G1 phase and decreased cell proportions in the S and G2/M phases. Co­IP analysis demonstrated that CREBBP interacted with E2F3a, a transcription factor involved in G1/S transition. Immunofluorescence confocal microscopy indicated co­localization of CREBBP and E2F3a at the cell nucleus. Furthermore, E2F3a protein expression decreased in CREBBP RNA interference treated Jurkat and Reh cells. CASP8AP2, a target gene of E2F3a, was also identified to be a downstream gene of CREBBP. In addition, decreased IC50 value and cell proportions in the G0/G1 phase, accelerated cell proliferation and upregulated E2F3a and CASP8AP2 expression were exhibited in CREBBP overexpressed cells. Taken together, the results of the present study suggested that CREBBP downregulation affects proliferation and cell cycle progression in leukemia cells, potentially via the interaction and regulation of E2F3a, resulting in chemotherapy resistance. Thus, targeting CREBBP may be a therapeutic strategy for treating pediatric patients with ALL.

[Research Progress of Desialylation in Immune Thrombocytopenia -Review].

Some patients diagnosed as immune thrombocytopenia(ITP) have poor response to common first-line therapy such as corticosteroid and immunoglobulin. Studies in recent years have found a FC-independent platelet clearance pathway exists, which is characterized by desialylation of platelet surface glycoprotein(GP), recognition and phagocytosis by Ashwell-Morell receptor(AMR) on hepatocytes, independent on Fc receptors of the reticuloendothelial system. The up-regulation of neuraminidase-1(Neu1) expression on platelet caused by various factors, such as cold storage of platelet, septicemia and ITP could desialylate GPs. It has been found that ITP with positive anti-GPIbα antibody mostly has a poor response to first-line therapy and indicated that such antibody may lead to FC-independent platelet clearance. It also has been proved that anti-GPIbα antibody could desialylate GPs on platelet in animal experiments. Researchers have tris to use sialidase inhibitor agent to treat ITP and got a persistent response of platelet. Here, the desialylation of platelet and its role in ITP pathogensis and therapy are reviewed.

Pharmacokinetic Studies of Factor VIII in Chinese Boys with Severe Hemophilia A: A Single-Center Study.

BACKGROUND: Although much attention has been paid to the pharmacokinetics (PKs) of different factor VIII (FVIII) concentrates in persons with hemophilia A (HA), limited information is available in young boys with severe HA. In this study, we aimed to assess the PK parameters of FVIII products in boys with severe HA in China. METHODS: A total of 36 boys (plasma-derived [pd]-FVIII, n = 15; recombinant [r] FVIII, n = 21) were enrolled between January 2015 and May 2016 in Beijing Children's Hospital. PK characteristics of FVIII products were studied according to a reduced 4-sampling time point design (1 h, 9 h, 24 h, and 48 h postinfusion). RESULTS: The mean FVIII half-life (t1/2) was 10.99 ± 3.45 h (range 5.52-20.02 h), the mean in vivo recovery (IVR) was 2.01 ± 0.42 IU/dl per IU/kg (range 1.24-3.02 IU/dl per IU/kg) and mean clearance (CL) of FVIII is 4.34 ± 1.58 ml·kg-1·h-1 (range 2.29-7.90 ml·kg-1·h-1). We also analyzed the influence of several parameters that potentially modulate FVIII PK. The age was closely associated with FVIII half-life (R2 = 0.32, P < 0.01). The t1/2of FVIII increased by 0.59 h per year. Besides age, von Willebrand factor antigen (VWF:Ag) also was associated with FVIII half-life (R2 = 0.52, P < 0.01). Patients with blood Group O had a shorter FVIII half-life than patients with non-O blood group (9.40 ± 0.68 h vs. 12.3 ± 0.79 h, t = 2.70, P = 0.01). The FVIII IVR correlated with age (R2 = 0.21, P < 0.01) and VWF:Ag level (R2 = 0.28, P < 0.01). CL rates were faster in young patients and in those with low-VWF:Ag levels. CL rates of FVIII are higher in blood Group O versus non-blood Group O persons (5.02 ± 0.38 vs. 4.00 ± 0.32 ml·kg-1·h-1, t = 2.53, P = 0.02). CONCLUSIONS: Chinese boys with severe HA have similar PK values to other ethnic groups and large differences in FVIII PK between individual patients. Age, blood group, and VWF:Ag levels are important determining factors for FVIII CL.

Polymorphisms in methotrexate transporters and their relationship to plasma methotrexate levels, toxicity of high-dose methotrexate, and outcome of pediatric acute lymphoblastic leukemia.

High-dose methotrexate (HDMTX) plays an important role in the treatment of acute lymphoblastic leukemia (ALL) although there is great inter-patient variability in the efficacy and toxicity of MTX. The relationship between polymorphisms in genes encoding MTX transporters and MTX response is controversial. In the present study, 322 Chinese children with standard- and intermediate-risk ALL were genotyped for 12 polymorphisms. SLCO1B1 rs10841753 showed a significant association with plasma MTX levels at 48 h (P = 0.017). Patients who had the ABCB1 rs1128503 C allele had longer duration of hospitalization than did those with the TT genotype (P = 0.006). No association was found between oral mucositis and any polymorphism. Long-term outcome was worse in patients with the SLCO1B1 rs4149056 CC genotype than in patients with TT or TC (5-year event-free survival [EFS] 33.3 ± 19.2% vs. 90.5 ± 1.7%, P < 0.001), and was worse in patients with the SCL19A1 rs2838958 AA genotype than in patients with AG or GG (5-year EFS 78.5 ± 4.6% vs. 92.2 ± 1.8%, P = 0.008). Multiple Cox regression analyses revealed associations of minimal residual disease (MRD) at day 33 (hazard ratio 3.458; P = 0.002), MRD at day 78 (hazard ratio 6.330; P = 0.001), SLCO1B1 rs4149056 (hazard ratio 12.242; P < 0.001), and SCL19A1 rs2838958 (hazard ratio 2.324; P = 0.019) with EFS. Our findings show that polymorphisms in genes encoding MTX transporters substantially influence the kinetics and response to HDMTX therapy in childhood ALL.

Low CREBBP expression is associated with adverse long-term outcomes in paediatric acute lymphoblastic leukaemia.

OBJECTIVES: CREBBP alterations are associated with many diseases including leukaemia. However, CREBBP expression and its clinical relevance in paediatric acute lymphoblastic leukaemia have not been elucidated. METHODS: We studied CREBBP mRNA expression in 349 patients treated with either the BCH-2003 or CCLG-2008 protocol. Using a receiver operating characteristic curve, patients were divided into low- or high-CREBBP. The association among clinicobiological characteristics, outcomes and CREBBP level was analysed. RESULTS: Low expression of CREBBP (<1.0) at diagnosis was found in 97.7% of patients and increased significantly after complete remission. Low-CREBBP patients were associated with unfavourable clinical presentations, poor prednisone response and high minimal residual disease (>10-2 ) after induction. We found significantly poorer event-free survival (EFS) and overall survival (OS) in low-CREBBP group whether administered BCH-2003 or CCLG-2008. Low-CREBBP was an inferior independent prognostic factor in BCH-2003; patients with low-CREBBP had better outcomes on an intermediate-risk regimen than a standard-risk regimen involving the CCLG-2008 protocol. Patients stratified to high-risk with low-CREBBP had the worst EFS and OS. CONCLUSIONS: These findings indicate that low-CREBBP is predictive of unfavourable outcomes; thus, a more intensive treatment protocol is necessitated for standard-risk patients with insufficient CREBBP and that a specific target therapy is necessitated for high-risk patients.

[Relationship between platelet specific antibodies and the onset, clinical manifestation, treatment and prognosis of ITP].

Immune thrombocytopenia (ITP) is an autoimmune hemorrhagic disease. It is considered that production of platelet auto-antibodies was one of the pathogenesis of ITP, first-line therapy including corticosteroid and immunoglobulin could reduce destruction of platelets by inhibiting production of auto-antibodies and blocking Fc-receptor of reticuloendothelial system, but some of the patients were refractory to first-line therapy and have persistent duration of the disease, having worse prognosis and developing into chronic/refractory ITP(C/RITP) . Platelet membrane glycoprotein like GPIIb/IIIa and GPIbα are the most common antigen targets, but first-line therapy was less effective to patients whose anti-GPIbα antibodies are positive. Further studies revealed that the way causing platelet destruction by anti-GPIIb/IIIa antibodies and anti-GPIbα antibodies are different: the former is mainly dependent to Fc-pathway, and the latter mainly cleared platelet by Fc-independent way. Results above indicated that detection of type of platelet auto-antibodies maybe potential to treatment and prognosis of ITP. This article summarizes relationship between platelet specific antibodies and the onset, clinical manifestation, treatment and prognosis of ITP.

FPGS rs1544105 polymorphism is associated with treatment outcome in pediatric B-cell precursor acute lymphoblastic leukemia.

BACKGROUND: Folypolyglutamate synthase (FPGS) catalyzes the polyglutamation of folates and antifolates, such as methotrexate (MTX), to produce highly active metabolites. FPGS tag SNP rs1544105C > T is located in the gene promoter. The aim of the present study was to investigate the impact of rs1544105 polymorphism on the treatment outcome in pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL). METHODS: This study enrolled 164 children with BCP-ALL. We genotyped the FPGS SNP rs1544105, and analyzed the associations between its genotypes and treatment outcome. We also examined FPGS mRNA levels by real-time PCR in 64 of the 164 children, and investigated the function of this polymorphism on gene expression. RESULTS: We found significantly poor relapse-free survival (RFS) (p = 0.010) and poor event-free survival (EFS) (p = 0.046) in carriers of CC genotype. Multivariable Cox regression analyses adjusted for possible confounding variables showed that, relative to the CT + TT genotypes, the CC genotype was an independent prognostic factor for poor RFS (hazard ratio [HR], 4.992.; 95% CI, 1.550-16.078; p = 0.007). No association was found between any toxicity and rs1544105 polymorphism. Quantitative PCR results showed that individuals with the T allele had lower levels of FPGS transcripts. CONCLUSIONS: Our study indicates that FPGS rs1544105C > T polymorphism might influence FPGS expression and affect treatment outcome in BCP-ALL patients.

The selective Hsp90 inhibitor BJ-B11 exhibits potent antitumor activity via induction of cell cycle arrest, apoptosis and autophagy in Eca-109 human esophageal squamous carcinoma cells.

BJ-B11 is a selective heat shock protein 90 (Hsp90) inhibitor that has been reported to possess significant antitumor activity in multiple types of cancer cells; however, the mechanism of action needs to be further clarified. We investigated, for the first time, the antitumor activity and the molecular mechanism underlying growth inhibition in Eca-109 cells. The results revealed that BJ-B11 inhibited the proliferation of Eca-109 cells in a time- and concentration-dependent manner, with 50% inhibitory concentration (IC(50)) values of 0.31±0.01 µM after 48-h incubation. BJ-B11 induced concentration-dependent G2/M cell cycle arrest and apoptosis. The cleavage of caspase 3 and PARP signals detected might originate from mitochondrial dysfunction, which was supported by the results of reactive oxygen species (ROS) production, cytochrome c release and the mitochondrial membrane potential (MMP) reduction. The general caspase inhibitor Z-VAD-fmk did not completely abolish BJ-B11-induced cell death. Furthermore, inhibition of the Akt/mTOR/p70S6K signaling pathway might be involved in the process of BJ-B11-induced autophagy, which was characterized by the production of autophagic vacuoles and upregulation of LC3-II protein in a time- and concentration-dependent manner. Meanwhile, the general autophagy inhibitor 3-MA decreased the apoptotic ratio. Furthermore, BJ-B11 induced the polymerization of cytoskeleton ß-tubulin and F-actin. Taken together, our results suggest that the growth inhibition of Eca-109 cells induced by BJ-B11 may result from the induction of G2/M cell cycle arrest, apoptosis and autophagy.

Cloning, soluble expression, rapid purification and characterization of human Cofilin1.

Cofilin1 is an actin-binding protein that plays a critical role in the regulation of actin cytoskeleton and consequently affects various physiological processes. In this study, the human Cofilin1 cDNA was cloned into the expression vector pET-28a(+) with a 6 × His tag and expressed as soluble protein in Escherichia coli BL21(DE3). Approximately 78 mg of Cofilin1, which showed high activity as determined by native PAGE, could be purified from each liter of LB medium by His-tag affinity chromatography and gel filtration. Further, high-titer IgG against Cofilin1 was positively detected after immunization in rabbits and the polyclonal antibodies were purified and identified. Together, this report provides the first protocol to efficiently obtain human Cofilin1 with high biological activity and immunogenicity using E. coli BL21 (DE3) expression system.

BJ-B11, a novel Hsp90 inhibitor, induces apoptosis in human chronic myeloid leukemia K562 cells through the mitochondria-dependent pathway.

In the past few years heat shock protein 90 (Hsp90) inhibitors have been reported to possess significant antitumor activity. We investigated, for the first time, the antitumor activity of a novel Hsp90 inhibitor 2-(4-acetyloxycyclohexylamino)-4-(3, 6, 6-trimethyl-4-oxo-4, 5, 6, 7-tetrahydro-1H-indazol-1-yl)-benzamide (BJ-B11) and the molecular mechanism underlying the apoptosis it induces in human chronic myeloid leukemia K562 cells. The results revealed that BJ-B11 triggered growth inhibition in K562 cells and other malignant cell lines in vitro with only minor toxicity in a normal human cell line. BJ-B11 inhibited the proliferation of K562 cells in a concentration- and time-dependent manner, with IC(50) values of 1.1 ± 0.2 µM and 0.4 ± 0.1 µM after 48 and 72 h incubations respectively. This most likely results from cell cycle arrest at the G(0)/G(1) phase and the induction of apoptosis. In addition, BJ-B11 degraded the Hsp90 client proteins Bcr-Abl and Akt, induced activation of caspase-9 and caspase-3, and subsequent cleavage of PARP. The caspase signals may originate from mitochondrial dysfunction, which is supported by the finding of cytochrome c release. In addition, inactivation of the Akt signaling pathway may be involved in the process of BJ-B11-induced apoptosis. Taken together, our data provide a putative molecular mechanism for the anticancer effect of BJ-B11 on K562 cells, and suggest a potential application for BJ-B11 in chronic myeloid leukemia therapy.

Notoginsenoside ST-4 inhibits virus penetration of herpes simplex virus in vitro.

Further study on steam-treated notoginseng, the roots of Panax notoginseng (Burk.) F.H. Chen (Araliaceae), which is a famous traditional Chinese medicine that is used both in raw and treated forms for a long time, led to the isolation of a new dammarane-type saponin, namely notoginsenoside ST-4. Its structure was elucidated to be 3ß,12ß,20(S)-tri-hydroxydammar-24-ene-3-O-ß-d-xylopyranosyl-(1 â†’ 2)-ß-d-glucopyranosyl-(1 â†’ 2)-ß-d-glu-copyranoside, based on the detailed analyses of the 1D and 2D NMR spectral data and acidic hydrolysis. Notoginsenoside ST-4 was investigated for its antiviral activity on herpes simplex type 1 (HSV-1) and type 2 (HSV-2) in vitro. The 50% effective concentration (EC(50)) values, determined by plaque reduction assay, were 16.47 ± 0.67 and 19.44 ± 1.16 µM for HSV-1 and HSV-2, respectively, whereas the 50% cytotoxic concentration (CC(50)) determined by the XTT test on Vero cells was 510.64 ± 4.56 µM. As analyzed by attachment assay and penetration assay based on plaque reduction assay, the antiviral activity of notoginsenoside ST-4 was principally due to the penetration inhibition effects, which was confirmed by fluorescence microscopy observation that notoginsenoside ST-4 blocked the penetration of virus. Therefore, notoginsenoside ST-4 might be a promising agent for herpes simplex virus infection.

[Immunoregulatory function of interleukin-6 on human Th17 cells].

The aim of this study was to explore the regulatory function of interleukin-6(IL-6) on human Th17 cells. Human peripheral blood CD4(+) T cells were purified from healthy donors by anti-CD4 monoclonal antibody (mAb) conjugated microbeads. The experiment was divided into 2 groups. Test group in which CD4(+) T cells (1 × 10(6)/ml) were stimulated by human recombined IL-6 (20 ng/ml) for 4 days; control group in which CD4(+) T cells did not stimulated by IL-6. The concentrations of IL-17 protein in the supernatants were assayed by enzyme-linked immunosorbent assay (ELISA), and quantity of Th17 cells were detected by flow cytometry. The results showed that as compared to control group, IL-17 protein level in the supernatants of CD4(+) T cells significantly increased in IL-6 stimulated group: (337.05 ± 189.09 pg/ml; vs 15.07 ± 12.70 pg/ml) (p < 0.05). Furthermore, the percentage of Th17 cells in cultures of CD4(+) T cells stimulated by IL-6 was significantly higher than that in control group (4.05% ± 0.30% vs. 2.81% ± 0.44%)(p < 0.01). It is concluded that IL-6 promotes the expansion of Th17 cells in vitro.

Decreased expression of MBD2 and MBD4 gene and genomic-wide hypomethylation in patients with primary immune thrombocytopenia.

Genome-wide hypomethylation has been confirmed in patients with primary immune thrombocytopenia (ITP). Proteins containing methylcytosine-binding domain (MBD) are involved in promoter methylation as transcriptional repressors and promote the gene-silencing effect of DNA methylation. The purpose of this study was to investigate the methylation pattern of T cells and the relationship between genomic methylation and the expression of MBD2 and MBD4 in ITP patients. DNA deoxymethylcytosine content of CD4(+) cells from peripheral blood mononuclear cells was measured by enzyme-linked immunoassay. Real-time polymerase chain reaction was performed to quantify the transcription levels of MBD2 and MBD4 in peripheral blood mononuclear cells and CD4(+) cells. DNA dmC content in CD4(+) cells of ITP patients was significantly lower than in the controls (p = 0.001). The mRNA level of MBD2 and MBD4 in CD4(+) cells of ITP patients was statistically lower than those of the controls (p < 0.001). Positive correlations between methylation indexes and expression of each enzyme were observed in the control group (r(2) = 0.718, p = 0.004 for MBD2; r(2) = 0.608, p = 0.015 for MBD4). However, inverse correlations were found in ITP patients (r(2) = 0.604, p = 0.008 for MBD2; r(2) = 0.498, p = 0.027 for MBD4). Our results indicate that decreased expression of MBD2 and MBD4 might involve in the pathogenesis of ITP.

Autophagy is involved in anti-viral activity of pentagalloylglucose (PGG) against Herpes simplex virus type 1 infection in vitro.

Pentagalloylglucose (PGG) is a natural polyphenolic compound with broad-spectrum anti-viral activity, however, the mechanisms underlying anti-viral activity remain undefined. In this study, we investigated the effects of PGG on anti-viral activity against Herpes simplex virus type 1 (HSV-1) associated with autophagy. We found that the PGG anti-HSV-1 activity was impaired significantly in MEF-atg7-/- cells (autophagy-defective cells) derived from an atg7-/- knockout mouse. Transmission electron microscopy revealed that PGG-induced autophagosomes engulfed HSV-1 virions. The mTOR signaling pathway, an essential pathway for the regulation of autophagy, was found to be suppressed following PGG treatment. Data presented in this report demonstrated for the first time that autophagy induced following PGG treatment contributed to its anti-HSV activity in vitro.

[Adenovirus-delivered BMI-1 shRNA].

Recently, some plasmid vectors that direct transcription of small hairpin RNAs have been developed, which are processed into functional siRNAs by cellular enzymes. Although these vectors possess certain advantages over synthesized siRNA, many disadvantages exist, including low and variable transfection efficiency. This study was aimed to establish an adenoviral siRNA delivery system without above-mentioned disadvantages on the basis of commercially available vectors. A vector was designed to target the human polycomb gene BMI-1. The pAd-BMI-1shRNA-CMV-GFP vector was produced by cloning a 300 bp U6-BMI-1 cassette from the pGE1BMI-1shRNA plasmid and a CMV-GFP cassette from pAdTrack CMV in pShutter vector. The adenovirus was produced from the 293A packaging cell line and then infected K562 cells. The mRNA and protein levels of Bmi-1 were detected by real time-PCR and Western blot respectively. The results showed that the adenovirus carrying the BMI-1shRNA was successfully produced. After being transfected with the adenovirus, the K562 cells dramatically down-regulated BMI-1 expression, whereas the adenoviruses carrying control shRNA had no effect on BMI-1 expression. It is concluded that the adenoviruses are efficient vectors for delivery of siRNA into mammalian cells and may become a candidate vector carrying siRNA drugs for gene therapy.

The role of T-cell immunoglobulin- and mucin-domain-containing molecule-3 polymorphisms in idiopathic thrombocytopenic purpura.

The family of T-cell immunoglobulin- and mucin-domain-containing molecules (TIMs) has an important role in immune regulation. TIM-3 is a transmembrane protein preferentially expressed on terminally differentiated Th1 cells and plays a role in T-helper (Th)-1-mediated autoimmune disease. Idiopathic thrombocytopenic purpura (ITP) is an acquired organ-specific autoimmune disease with a polarization of Th1. The purpose of this study was to investigate whether the -1516G>T, -574T>G, 4259G>T single-nucleotide polymorphisms within the TIM-3 gene contribute to the genetic susceptibility to ITP. Genotyping of TIM-3 -1516G>T, -574T>G, and 4259G>T was performed in 187 patients with ITP and 123 healthy individuals by polymerase chain reaction-restriction fragment length polymorphism assay. No significant differences existed in genotype and allele distributions between the patients with ITP and the controls in all three sites. There was strong linkage disequilibrium (LD; r(2) = 0.633) between -574T>G and 4259G>T, whereas -1516G>T was not in LD with -574T>G (r(2) = 0.007) or with 4259G>T (r(2) = 0.002). The -1516G>T, -574T>G, and 4259G>T of TIM-3 gene polymorphisms might not play an important role as a genetic risk factor in the pathophysiology of ITP.

[Effect of silencing bmi-1 by RNA interference on function of K562 cell line].

Bmi-1 is a transcriptional repressor, which belongs to the polycomb group family. It has been demon- started that over-expression of Bmi-1 occurs in a variety of cancers, including several types of leukemia. Bmi-1 gene plays a key role in regulation of self-renewal in normal and leukemic stem cells. Acute myeloid leukemic cells lacking Bmi-1 undergo proliferation arrest and show signs of differentiation and apoptosis, which leads to the proposal of Bmi-1 as a potential target for therapeutic intervention in leukemia. The purpose of this study was to investigate the effect of short hairpin RNA (shRNA) targeting Bmi-1 on functions of K562 cell line. The shRNA eukaryotic expression vector targeting Bmi-1 was constructed and transfected into K562 cells through lipofectamine 2000. The mRNA and protein levels of Bmi-1 were detected by PCR and Western blot respectively. The proliferation of K562 after Bmi-1 silencing was measured by using MTT assay and clone formation assay. The cell cycle was detected by flow cytometry. The results indicated that among the four shRNA designed, there was a shRNA which efficiently interfered with the expression of Bmi-1. The results of PCR and Western blot validated that the Bmi-1 gene of K562 cells transfected with such a Bmi-1 shRNA was suppressed successfully. Although levels of Bmi-1 mRNA and protein were significantly reduced, delivery of this siRNAs had no effect on cell viability or growth. Flow cytometry analysis suggested that Bmi-1 inhibition did not affect the cell cycle. It is concluded that the suppression of Bmi-1 expression is not able to reduce proliferation of K562 cells, suggesting existence of some other parallel signaling pathways, which are fundamental for leukemic transformation and are independent of Bmi-1 over-expression. Bmi-1 over-expression may play a secondary role in chronic myeloid leukemia transformation.

[Expression of human factor IX in retrovirus-transfected human umbilical cord tissue derived mesenchymal stem cells].

The purpose of this study was to investigate the expression of human Factor IX (hFIX) in retrovirus-transfected human umbilical cord tissue derived mesenchymal stem cells (hUCT-MSCs). The pLEGFP-N1-hFIX vector was generated by cloning a 3.0 kb Bgl II-BamH I fragment from the pIRES2-EGFP-hFIX plasmid containing the hFIX cDNA and part of intron 1 of hFIX in pLEGFP-N1 vector. The retroviral supernatants were produced from the Phoenix packaging cell line and then infected the hUCT-MSCs. After selection with G418 for 10 day, the expression of FIX was detected by ELISA and Western blot. The biological activity of FIX was determined by the clotting assay employing human Factor IX-deficient plasma. The results showed that compared with the activity of pooled human normal plasma (100%), transduced cells produced biologically active hFIX with 100-130% activity in two-day culture supernatant and expressed hFIX at levels of 2.68 +/- 0.36 microg/10(6) cells/24 hours after G418 selection for 10 days. The secretion of hFIX into culture supernatant was also confirmed by Western blot analysis. It is concluded that genetically modified hUCT-MSCs can express biologically active hFIX and thus serve as an efficient drug delivery vehicle carrying hFIX used as a way of somatic gene therapy for hemophilia B.

[Mesenchymal stem cells derived from human umbilical cord tissue modulate the secretion of antiplatelet antibody from splenocytes of ITP patients in vitro].

The study was aimed to investigate the potential immunotherapeutical values of umbilical cord tissue-derived mesenchymal stem cells (UC-MSC) on patients with chronic idiopathic thrombocytopenic purpura (ITP). UC-MSC was cocultured in vitro with splenocytes isolated from ITP patients who experienced splenectomy. The level of IgG antiplatelet antibody (PAIgG) was determined by a competitive micro-enzyme-linked immunosorbent assay (ELISA) method. The proliferation of platelet-reactive CD4+ T lymphocytes was also measured in the presence of UC-MSCs. The results showed that UC-MSCs could stimulate the spontaneous secretion of PAIgG in supernatants; In the platelet-inducing condition, UC-MSC inhibited the production of PAIgG at a low ratio of 1 UC-MSC to 100 splenocytes, but promoted at a high proportion of 1 UC-MSC to 10 splenocytes. Moreover, UC-MSC exerted a suppressive effect on proliferation of platelet-reactive T helper cells in a dose-dependent manner. It is concluded that the UC-MSCs can regulate secretion of antiplatelet antibodies in vitro. Its concrete regulation mechanism and potential immunotherapeutical value are need to further study.