[Oxidative Damage of Bone Marrow Stromal Cells Caused by Chemotherapy Drugs].

OBJECTIVE: To explore the oxidative damage of OP9 cells induced by daunorubicin (DNR) treatment. METHODS: The TMRM probe was used to detect mitochondrial membrane potential by flow cytometry; the reactive oxygen species (ROS) was determined by flow cytometry DCFDA probe; the real-time PCR was used to detect the molecular expression of antioxidant enzyme，glutathione peroxidase (GPX) in OP9 cells; the expression of γ-H2AX was determined by flow cytometry. RESULTS: Compared with normal OP9 cells, the positive rate of TMRM in DNR-treated OP9 cells decreased by 56.7% (P＜0.05); the positive rate of DCFDA in DNR-treated OP9 cells increased by 3.52 times (P＜0.01). Compared with normal OP9 cells, DNR-treated OP9 cells showed a decrease in the expression of GPX4 by 44.22% (P＜0.001); the expression of GPX7 decreased by 65.7% (P＜0.001); the expression of GPX8 decreased by 24.7% (P＜0.001); the positive rate of γ-H2AX in DNR-treated OP9 cells increased (P＜0.05). CONCLUSION: After DNR treatment, mitochondrial membrane potential of OP9 cells decreases; the level of reactive oxygen species increases; the expression of glutathione peroxidase (GPX) molecules decreases significantly; genomic instability increases obviously; the oxidative damage of cells increased.

[Effect of Chemotherapeutic Drug-Induced Damage of Bone Marrow Stroma Cells on Normal Hematopoietic Cells].

OBJECTIVE: To explore the effect of damage of bone marrow stroma cells induced by chemotherapeutic drug on the function of normal hematopoitic cells. METHODS: Senescence cells were detected by flow cytometry after SA-ß-gal staining; real-time PCR was used to detect the expression of a serial molecules in bone marrow stromal cell line OP9 cells; the expression of γ-H2AX was determined by flow cytometry after histone γ-H2AX staining; the colony forming ability of hematopoietic cells was tested by colony formation assay. RESULTS: The percentage of senescence cells in OP9 cells after DNR treatment was 2.24 times as much as that in untreated OP9 cells (P<0.05). Compared with normal OP9 cells, the expression levels of IL-6 and TNF-alpha in DNR-treated OP9 cells increased by 2.73 times (P<0.01) and 0.56 times (P<0.01), and the expression levels of N-cadherin, alpha smooth muscle actin (alpha-SMA), angiopoietin1 (Angpt1) and osteopontin (OPN) decreased by 69.54%（P<0.01），63.90%（P<0.01），87.41%（P<0.01）and 42.78%（P<0.01）respectively. After the co-culture with DNR-treated OP9 cells, the colony formation of normal hematopoietic cells decreased by 47.10% than that co-cultured with untreated OP9 cells (P< 0.05), meanwhile, the percentage of γ-H2AX+ cells in normal hematopoietic cells increased by 2.19 times (P<0.05). CONCLUSION: After treatment with DNR, the senescence cell number of OP9 cells sgnificantly increases; the expression of TNF-α and IL-6 is up-regulated, while the expression of α-SMA, Angpt-1 and OPN is down-regulated as compared with normal OP9 cells. In addition, after co-culture of DNR-treated OP9 cells with normal hematopoietic cells, the colony formation ability of hematopoietic cells decreases and the genome instability of hematopoietic cells increases as compared with normal hematopoietic cells.

[Relationship between High Expression of c-FLIP and Drug Resistance of Leukemia Cells].

OBJECTIVE: To explore the effect of c-FLIP expression on drug resistance of Kasumi-1 leukemia cells and its mechanisms. METHODS: Tet-on inducible system was used to construct the conditional expression vector of c-FLIP by cloning the c-FLIP gene into lentivirus vector pLVX-Tight-Puro, then the Kasumi-1 cells were transfected with lentivirus pLVX-Tight-Puro-c-FLIP. The expression of c-FLIP was induced by doxycycline(Dox) for different time and doses, and verified by qRT-PCR and Western blot. On the basis of the overexpression of c-FLIP, the Kasumi-1-c-FLIP cells were treated with CH11 and PB in order to induce apoptosis, and the Giemsa staining was used to show the apoptotic cell morphology. RESULTS: qRT-PCR and Western blot showed the overexpression of c-FLIP, the CH11 and PB can induce Kasumi-1 cell apoptosis, while the c-FLIP overexpression weakened this effects. Western blot showed that the c-FLIP blocked the caspase-8 activation. CONCLUSION: The overexpression of c-FLIP inhibits the apoptosis caused by CH11 and PB, and leads to drug resistance in leukemia cells.

Functional Variant of C-689T in the Peroxisome Proliferator-Activated Receptor-γ2 Promoter is Associated with Coronary Heart Disease in Chinese Nondiabetic Han People.

Objective To investigate the association between the polymorphism of C-689T in the peroxisome proliferator-activated receptor-γ2 (PPARγ2) promoter and coronary heart disease (CHD). Methods This case-controlled study was conducted in nondiabetic Chinese Han people, which enrolled 455 patients with CHD (cases) and 693 subjects without CHD (controls). Data of clinical indexes were collected, including height, body weight, waist circumstance, systolic blood pressure (SBP), diastolic blood pressure (DBP), smoking, drinking, physical activity, as well as body mass index (BMI). Fasting blood glucose (FBG), plasma total cholesterol (TC) and triglyceride (TG) levels were measured. Polymerase chain reaction-restricted fragments length polymorphism (PCR-RFLP) was used to determine the PPARγ2 promoter C-689→T substitution. The genotype distribution of PPARγ2 promoter C-689T, allelic frequency, clinical indexes, and laboratorial measurements were compared between the two groups. The effect of genotype on the risk of CHD was assessed using univariate and multivariate regression model. Results The genotype frequencies of CC, CT and TT in PPARγ2 promoter C-689T were 89.7%, 9.9% and 0.4% in the case group, and 93.1%, 6.6% and 0.3% in the control group, respectively (CC vs. CT+TT, χ2= 6.243, P=0.041). Carriers of -689T allele (n=95) had significantly higher TC level than non-carriers (n=1053) (5.12±1.26 vs. 4.76±1.22 mmol/L, P=0.001). Male carriers of -689T allele (n=51) were significantly higher in waist circumference, body weight, TC and TG than male non-carriers (n=656) (all P<0.05). In subjects whose BMI was over 25 kg/m2, carriers of -689T allele (n=82) had significantly higher levels of waist circumference, BMI, SBP and TC than non-carriers (n=231) (all p<0.05). The -689T allele was an independent risk factor for CHD (OR=1.668, 95%CI: 1.031-2.705, P=0.037) after adjusting for age, gender, waist circumference, body weight, BMI, smoking, physical activities, SBP, DBP, FBG, TC and TG level. Conclusion These data support the hypothesis that the -689T allele is associated with an increased risk of CHD, in Chinese Han people and correlates significantly with the profiles of CHD-related risk factors.

[Expression and Asymmetric Division of Numb in Leukemia Cell K562 Line].

OBJECTIVE: To investigate the role of asymmetric division in leukemia cells through detection of expression and asymmetric division of Numb in differentiated and undifferentiated K562 cells. METHODS: Firstly, Hemin was used to induce K562 cell differentiation, and the expression of Numb was detected by the real-time quantitative RT-PCR and flow cytometry. After K562 cells were synchronized by nocodazole, the Numb protein was labeled by immunohistochemical staining, followed by the determination of the terminally differentiated cells through confocal microscopy. The fluorescence intensity was calculated by Image J software, and the cell division pattern was analyzed on the basis of the fluorescence intensities of Numb in 2 divided daughter cells. RESULTS: Compared with the undifferentiated K562 cells, the level of Numb mRNA expression increased 2.3 times (P<0.001). The ratio of Numb positive cells was(67.37±5.01)% in differentiated K562 cells, while that was (43.97±5.72)% in undifferentiated K562 cells (P<0.01). Compared with undifferentiated K562 cells, the ratio of cells with asymmetric division in differentiated K562 cells increased 18.3%, the percentage of cells with symmetry self-renewal reduced 49.7%(P<0.001) and that with symmetry differentiation increased 32%(P<0.001). CONCLUSION: In differentiated K562 cells, expression of Numb and proportion of cells with asymmetric division were higher than that in undifferentiated cells. With the differentiation of leukemia cells, the proportion of cells with asymmetrical division increases, and the proportion of cells with symmetrical self-renewal decreases. The stemness of leukemia cells is maintained mainly through the symmetrical self-renewal.

[Reconstruction of Humanized Bone Marrow Niche in Immunodeficiency Mouse].

OBJECTIVE: To reconstruct a human bone marrow niche in immunodeficiency mouse (NOD/SCID) so as to provide a model for observing the effect of abnormal BM niche on the occurence and development of leukemia. METHODS: Human platelet lysate(HPL) was obtained by repeated freezing and thawing of concentrated platelet. Bone marrow-derived mesenchymal stem cells were cultured in α-minimal essential medium (α-MEM) containing 10% HPL or 10% FBS. The morphology, cell phenotype, multilineage differentiation potential in vitro and proliferation capacity between the mesenchymal stem cells cultured with HPL or FBS were compared. The human bone marrow formation capacity of HPL-cultured MSC was observed. The MSC was seeded on ß-TCP scaffolds for 12h, then the MSC-coated scaffold were implanted in a subcutaneous pocket on the dorsum of NOD/SCID mice. After 8-12 week, the scaffolds were harvested from the mice, then fixed, paraffin-embedded and stained for HE. RESULTS: Whether cultured in the presence of HPL or FBS, the MSC all displayed a spindle-shaped fibroblast-like morphology; the flow cytometry analysis revealed no obvious differences in cell immunophenotype in this 2 groups; they all have the ability to differentiate towards osteoblasts, adipocytes, and chondrocytes in vitro. However, the mesenchymal stem cells cultivated with HPL-contained medium showed stronger proliferation capacity and higher activity to differentiate towards osteoblasts. Mesenchymal stem cells cultivated with HPL still have in vivo bone-forming capacity. CONCLUSION: HPL cultured MSC have stronger proliferation capacity and potential of differentiate towards osteoblasts, HPL-cultured MSC also can reconstruct humanized bone marrow niche in murine host.

Impact of Abdominal Shape on Short-Term Surgical Outcome of Laparoscopy-Assisted Distal Gastrectomy for Gastric Cancer.

BACKGROUND: Laparoscopy-assisted distal gastrectomy (LADG) has been widely accepted for the treatment for gastric cancer. The aim of the present study was to explore the impact of abdominal shape parameters on gastric antrum cancer patients' short-term surgical outcomes of LADG with D2 lymph node dissection in both genders, including the number of lymph nodes retrieved and surgical safety index. METHODS: This was a retrospective analysis of 177 gastric antrum cancer patients, who underwent LADG between April 2009 and January 2016. The abdominal shape parameters, including abdominal anterior-posterior diameter (APD), transverse diameter (TD), xiphoid process of the sternum-navel distance (XND), and thickness of subcutaneous fat (SCF) at the umbilicus level, were calculated by preoperative abdominal computed tomography (CT) scans. The effects of abdominal shape parameters on the short-term surgical outcomes of LADG were analyzed. RESULTS: In male patients undergoing LADG and D2 lymph node dissection, the number of retrieved lymph nodes was significantly lower in patients with APD ≥17.3 cm (P = 0.005), TD ≥27.4 cm (P = 0.029), SCF ≥1.2 cm (P = 0.014), and BMI ≥22.2 (P = 0.008), whereas in female patients, these were statistically insignificant (P > 0.05). APD, TD, SCF, and BMI were negatively correlated with the number of retrieved lymph nodes in male patients. There was no significant difference in the number of lymph nodes retrieved between high-XND group and low-XND group in either gender. Operation time was significantly shorter in male patients with XND < 17.0 cm (P = 0.044) and in female patients with SCF < 2.15 cm (P = 0.013). Intraoperative blood loss and postoperative complication rate were not significantly different between high- and low-APD groups, high- and low-TD groups, high- and low-XND groups, and high- and low-SCF groups in either gender. Compared with male patients, SCF and TD were significantly higher in female patients. In addition, a higher incidence rate of hypertension was observed in patients of both genders with large APD and SCF, although statistically significant only in male patients. CONCLUSIONS: LADG with D2 lymph node dissection can effectively achieve the lymph node dissection requirement of radical distal gastrectomy for patients with various abdominal shapes. It is worth noting that APD, TD, and SCF can impact on lymph node dissection of LADG in male patients. Nevertheless, in female patients, abdominal shape do not impact on lymph node dissection of LADG. Moreover, LADG with D2 lymph node dissection is proved to be safe for various abdominal shape in both genders, even for abdominal obese patients.

[Effect of TBLR1-RARα Fusion Gene on Erythroid Differentiation of K562 Cells].

OBJECTIVE: To explore the effects of TBLR1-RARα on the differentiation induction of leukemia cell line K562 cells into erythroid lineage and to investigate its related mechanisms. METHODS: Tet-Off inducible system was used to construct the conditional expression vector of TBLR1-RARα fusion gene by cloning the TBLR1-RARα fragment into lentivirus vector pLVX-Tight-Puro, the expression of TBLR1-RARα fusion gene was induced by doxycycline (Dox). Then, K562 cells were transfected with lentivirus pLVX-Tight-Puro-TBLR1-RARα-flag, and the expression of fusion proteins was verified by Western blot. After treatment of K562 with all-trans retinoid acid (ATRA), real time RT-PCR was performed to test the expression of erythroid differentiation-related CD71 and α, ε, γ-globins gene. Flow cytometry was used also to analyze the expression of erythroid differentiation markers CD71 and CD235a. Benzidine staining was used to detect the production of hemoglobin in K562 cells. RESULTS: qRT-RCR showed that ATRA could increase the expression level of CD71 and α, ε, γ-globin genes when TBLR1-RARα was expressed. After treatment of ATRA, the proportion of CD71(+) cells detected by the flow cytometry also increased. Benzidine staining showed that ATRA could induce hemoglobin production in K562 cells with TBLR1-RARα fusion gene expression. CONCLUSION: The expression of TBLR1-RARα fusion gene contribute to ATRA-inducing differentiation of K562 cells into erythroid lineage.

Inhibition of Forkhead box protein M1 by thiostrepton increases chemosensitivity to doxorubicin in T-cell acute lymphoblastic leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive type of blood malignancy, deriving from T-cell progenitors in the thymus, and comprises 10-15% of pediatric and 25% of adult primary ALL cases. Despite advances, 20% of pediatric and the majority of adult patients with T-ALL succumb to mortality from resistant or relapsed disease, and the survival rate for patients with resistant or relapsed T-ALL remains poor. Alterations in the expression of Forkhead box protein M1 (FoxM1) have been detected in several types of cancer, and the inhibition of FoxM1 has been investigated as therapeutic strategy in cancer. The present study investigated the effects of the inhibition of FoxM1 by thiostrepton in human T-ALL Jurkat cells. The cells were treated with different concentrations of thiostrepton, either alone or in combination with doxorubicin. Cell viability was measured using CCK-8 assays and the cell cycle distribution, apoptosis and cell-associated mean fluorescence intensity of intracellular doxorubicin were assessed using flow cytometric analysis. The mRNA and protein expression levels were detected by reverse transcription-quantitative polymerase chain reaction and western blot analyses. The inhibition of FoxM1 by thiostrepton significantly decreased the proliferation of the Jurkat cells proliferation in a time- and dose-dependent manner. Cell arrest at the G2/M phase, and apoptosis was significantly increased in the thiostrepton-treated Jurkat cells. Thiostrepton reduced the half maximal inhibitory concentration of doxorubicin in the Jurkat cells, and significantly enhanced the cytotoxicity of doxorubicin within the Jurkat cells by enhancing doxorubicin-induced apoptosis and increasing the accumulation of intracellular doxorubicin. Furthermore, the inhibition of FoxM1 by thiostrepton enhanced doxorubicin-induced apoptosis, possibly through a caspase-3-dependent pathway, and increased the accumulation of intracellular doxorubicin, possibly through downregulating the expression of glutathione S-transferase pi. Collectively, the results of the present study suggested that targeting FoxM1 with thiostrepton resulted in potent antileukemia activity and chemosensitizing effects in human T-ALL Jurkat cells.

[Role of IFN-γ in the regulation of murine hemopoiesis].

This study was aimed to explore the role and mechanism of IFN-γ in the regulation of hemopoiesis in mice. Murine IFN-γ fragment was amplified from murine splenic cells with RT-PCR and plasmid pCDH1-mIFN-γ-EF1-copGFP (pCDH-mIFN-γ-GFP) was constructed. Plasmids pCDH-mIFN-γ-GFP and pCDH1-EF1-copGFP (pCDH-GFP) together with packaging plasmids pPACK-A, pPACK-B and pPACK-C were respectively transfected into 293T cells by using a method of calcium phosphate precipitation to produce lentivirus. Bone marrow mononuclear cells (BMMNC) from male C57BL/6J mice were transfected with the lentiviral vector pCDH expressing mIFN-γ and green fluorescent protein (GFP). The cells were cultured in M3434 semi-solid medium for colony formation assay and transplanted into lethally-irradiated mice through caudal vein injection, and the peripheral blood cell counts and GFP were monitored regularly after transplantation. The results showed that lentiviral vector pCDH-mIFN-γ-GFP was constructed successfully and 293T cells transfected with mIFN-γ secreted mIFN-γ. Transfection of mIFN-γ into BMMNC decreased colony formation, colony number of the mIFN-γ group was significantly less than that of the control group. The recovering of circulating blood cell parameters in mIFN-γ transplantation group was significantly later than control group. GFP positive cells could be detected in the peripheral blood at 8 weeks after transplantation. It is concluded that mIFN-γ may inhibit the colony-forming capacity of transduced BMMNC and delay the hematopoietic reconstitution.

[Dexamethasone and vorinostat cooperatively promote differentiation and apoptosis in Kasumi-1 leukemia cells through ubiquitination and degradation of AML1-ETO].

OBJECTIVE: To probe the effects of dexamethasone (DEX) combined with histone deacetylase (HDAC) inhibitor vorinostat on inhibiting proliferation and inducing differentiation and apoptosis in Kasumi-1 leukemia cells, and its possible mechanisms in order to provide a theoretical basis for the treatment of AML1-ETO positive AML. METHODS: The cell survival, differentiation and apoptosis rates were tested by MTT or flow cytometry analysis after Kasumi-1 cells were treated by DMSO, DEX (20 nmol/L), vorinostat (1 µmol/L) or DEX (20 nmol/L) in combination with vorinostat (1 µmol/L). WB and IP-WB were performed to detect AML1-ETO and its ubiquitination. RESULTS: Treatment with the combination of DEX and vorinostat for 48 h led to statistically significant differences of inhibited proliferation [(42.06±8.20)%], increased differentiation [(52.83±8.97)%] and apoptosis [(52.92±2.53)%] of Kasumi-1 cells when compared with vorinostat [(33.82±9.41)%, (43.93±9.04)% and (42.98±3.01)%, respectively], DEX [(17.30±3.49)%, (22.53±4.51)% and (19.57±2.17)%, respectively] or control [(6.96±0.39)%, (21.73±2.03)% and (6.96±0.39)%, respectively]. Also significant ubiquitination and decreased AML1-ETO protein in Kasumi-1 cells after the combination treatment over single agent or control were observed. CONCLUSION: The results indicated that DEX and vorinostat could synergistically inhibit the Kasumi-1 cells proliferation, induce Kasumi-1 cells differentiation and apoptosis through ubiquitination and degradation of AML1-ETO.

[Effects of transcription factor GATA-2 on transcriptive regulation of iASPP gene].

iASPP can prompt the cell proliferation and inhibit the apoptosis of many cells. There are putative binding sites of transcription factor GATA-2 upstream of iASPP transcription start site. GATA-2 plays an important role in the proliferation and differentiation of hematopoietic stem cells (HSC) and progenitors. This study was aimed to explore the role of GATA-2 protein in iASPP gene transcription. Firstly, the expression of iASPP and GATA-2 protein in some leukemia cell lines was detected by Western blot. Second, The expressive vector of pCMV5-GATA2 and the luciferase reporter vectors containing possible binding sites of GATA-2 were constructed and co-transfected into HEK293 and CV-1 cells. Then the luciferase activity was assayed by luminometer. Also, ChIP assays were performed to further confirm the specific binding of GATA-2 to iASPP promoter. The results showed that GATA-2 was overexpressed in most cell lines with high level of iASPP. GATA-2 exhibited a significant effect on luciferase activity of reporter gene iASPP and in a dose-dependant manner. The relative luciferase activity was up-regulated to about two-fold of the empty vector control when the transfection dose of pCMV5-GATA2 plasmid was increased to 100 ng. While the effect was more significant in CV-1 cells and showed a 6.7-fold increase. The ChIP assay demonstrated the in vivo specific binding of GATA-2 to iASPP. The binding sites of GATA2 were located between nt -361 ∼ -334 in upstream of iASPP gene transcription start site. It is concluded that transcription factor GATA-2 can bind with the cis-regulatory region of the iASPP promoter and up-regulate iASPP expression.

[Effect of cyclophosphamide on murine bone marrow hematopoietic cells and its possible mechanism].

This study was purposed to investigate the effect of chemotherapeutic drug cyclophosphamide (CTX) on normal murine bone marrow hematopoietic cells, especially on the self-renewal, proliferation and differentiation of bone marrow hematopoietic cells, and possible mechanisms. The CTX-treated mouse model was established by CTX 200 mg/kg, ip. The exact time of complete recovery of hematopoiesis was determined by monitoring the recovery level of differential blood counts and the proportion of LKS(+) cells in bone marrow cells. The function of bone marrow hematopoietic cells such as self-renewal, proliferation and differentiation were assessed by non-competitive and competitive bone marrow transplantation. The potential effect of CTX on senescence of bone marrow hematopoietic cells was analyzed by detecting p16(Ink4a) mRNA relative expression and SA-ß-galactosidase (gal) staining. The results showed that the CTX could induce long-term but latent damage to bone marrow hematopoietic cell function and lead to the decrease in competency of bone marrow hematopoietic cells to reconstitute while seemingly permitting a complete recovery. Furthermore, the serial-transplantation model showed that these mice received transplantation of bone marrow hematopoietic cells from CTX-treated mice exhibited a high expression of p16(Ink4a) mRNA and SA-ß-gal staining. It is concluded that CTX-induced bone marrow cellular senescence may play an important role in CTX-induced long-term injury to bone marrow hematopoietic cells.

[Expression of c-MPL in leukemic stem cells from acute myeloid leukemia patients].

This study was aimed to investigate the expression of c-MPL in acute myeloid leukemia (AML) and the correlation of the c-MPL expression with CD34 and CD38, so as to define the expression of c-MPL in leukemic stem cells. The expression levels of CD34, CD38 and c-MPL were detected by flow cytometry in bone marrow cells from 29 newly diagnosed AML patients. The relationship of c-MPL positive cell ratio with clinical parameters and correlation of c-MPL with CD34 and CD38 expression in AML patients were analyzed. The results showed that expression level of c-MPL in AML patients was significantly higher than that of normal controls (P < 0.05), and the expression level of c-MPL did not correlate with age, sex, white blood cell count, AML1-ETO fusion gene and remission after chemotherapy, but the expression of c-MPL in M2 and M5 patients was higher than that of normal control (P < 0.05). Expression of c-MPL in CD34 positive AML patients was obviously higher than that in CD34 negative AML patients (P < 0.01). c-MPL was significantly higher expressed in CD34(+) cells than that in CD34(-) cells (P < 0.001), while c-MPL expression was not significantly different between CD34(+)CD38(-) and CD34(+)CD38(-) cell groups. Positive correlation between c-MPL and CD34 expression was observed (r = 0.380, P = 0.042). It is concluded that expression of c-MPL is higher in AML patients, and positively correlates with the expression level of CD34. The c-MPL expresses in leukemic stem cells.

[Study on expression of PTEN gene and its pseudogene PTENP1 in acute leukemia and correlation between them].

OBJECTIVE: To investigate the expression of PTEN (phosphatase and tension homology deletion on chromosome 10, PTEN) and its pseudogene PTENP1 in acute leukemia (AL) and correlation between them, and to explore the role of PTENP1 on the PTEN expression in AL cells. METHODS: PTEN and PTENP1 mRNA expression were evaluated in bone marrow (BM) samples from 138 newly diagnosed AL patients and 15 healthy controls by quantitative real-time RT-PCR (qRT-PCR). pCDH1-PTENP1 3'UTR-GFP lentivirus vectors were constructed. 293T cells were transfected by calcium phosphate precipitation to produce retrovirus. HL-60 cell line was infected with the retroviral vectors expressing pCDH1-GFP and pCDH1-PTENP1 3'UTR-GFP respectively. The flow cell sorter was used to sort the HL-60 with GFP positively expressed. The mRNA expression of PTEN and PTENP1 was detected by qRT-PCR, the expression of PTEN protein by western blot, and the impact of PTENP13'UTR on the proliferation of HL-60 cells by MTT assay. RESULTS: AML patients showed significantly lower PTEN and PTENP1 mRNA expression in BM compared to healthy controls. Correlation analysis showed that the expression of PTEN and PTENP1 mRNA were positively correlated (P < 0.05). The 108 cases of PTENP1(+) AML were classified according to the prognostic classification of 2011 NCCN Clinical Practice Guidelines in AML, there was no difference among different subgroups. HL-60 cell line was infected with the retroviral vectors expressing pCDH1-GFP (control group) and pCDH1-PTENP1 3'UTR-GFP respectively. Compared with the control group, PTENP1 mRNA level of HL-60 infected with the retroviral vectors expressing pCDH1-PTENP1 3'UTR-GFP increased significantly, and PTEN mRNA level also increased. While the PTEN protein level and the cell growth rate of the PTENP1 3'UTR group didn't change significantly. CONCLUSION: PTEN and PTENP1 mRNA expression level of BM cells from AL patients is significantly lower. There is a positive correlation between expression of PTEN and PTENP1 mRNA. PTENP1 may regulate the expression of PTEN in mRNA level.

[Role of AML1a in abnormal proliferation and differentiation of murine hematopoietic cells].

This study was aimed to explore the role and mechanism of AML1a in abnormal hematopoiesis in mice. Plasmids pMSCV-FLAG-AML1a-IRES-YFP and pMSCV-IRES-YFP together with envelope-encoding plasmid pECO and packaging plasmid pGP were respectively transfected into 293T cells by using a method of calcium phosphate precipitation to produce retrovirus. Bone marrow mononuclear cells (BMMNC) from male C57BL/6J mice were transfected with the retroviral vector MSCV expressing FLAG-AML1a fusion protein and yellow fluorescent protein (YFP). The cells were cultured in M3434 semi-solid medium for colony formation assay and in M5300 fluid medium containing murine IL-3 (mIL-3), IL-6 (mIL-6) and SCF (mSCF) for long-term culture. The results showed that transfection of AML1a into BMMNC enhanced colony formation, colony size of the AML1a group was significantly larger than that of the control group, and the colonies were mainly composed of CFU-E and CFU-GEMM. In the long-term culture, AML1a-transfected BMMNC showed differentiation block, while the control cells were in a more mature stage. It is concluded that AML1a may block the normal hematopoiesis at the stage of primitive progenitors. At the same time, AML1a also enhances the proliferation activity of primitive progenitor cells.

[Dynamic monitoring of minimal residual disease in acute lymphoid leukemia].

The aim of this study was to establish a method for quantitative detection of immunoglobulin heavy chain (IgH) gene rearrangements and to explore its clinical application in monitoring minimal residual disease (MRD) of acute lymphoid leukemia (ALL). Clonal IgH gene rearrangements in 51 patients with ALL at diagnosis were identified by multiplex PCR assay. PCR products were sequenced and pairwise in IMGT data base. Allele-specific oligonucleotides primers were designed complementary to the junctional region. The conservative JH primers combined with TaqMan probes were used to monitor the level of MRD in ALL patients. The sensitivity and specificity were assessed as well. The results indicated that out of all the 51 ALL patients, IgH rearrangements were identified in 21 cases, and 15 patients out of them were quantified. The slope of the standard curves was -3.1 to -3.9 and the correlation coefficients of all standard curves were > 0.98. The sensitivity was between 10(-4) and 10(-5), only one patient's sensitivity was 10(-3). Most of the quantitative range was less than 10(-4). The background's nonspecific amplification was detectable at a low level and had a little influence on results. 7 patients whose MRD level below 10(-3) kept complete remission and another 8 patients whose MRD level above 10(-3) had a higher relapse rate. It is concluded that the analysis of IgH gene rearrangements with RQ-PCR is a highly sensitive, specific and reliable method for accurate evaluation of MRD in ALL. The data indicates a high correlation between the level of IgH rearrangements and the prognosis in ALL patients.

[Resistance of leukemia KG1a cells with positive N-cadherin in phase G(0) against killing activity of VP16].

Drug resistance is an important character of leukemic stem cells. To explore the mechanism of the chemotherapy resistance of N-cadherin positive leukemia cells, the quiescent state of N-cadherin positive leukemia cells was determined by flow cytometry and the relationship of G(0) phase cell ratio with the chemotherapy resistance was analyzed. After KG1a cells were induced to enter cell cycle, the G(0) phase cell ratio and the sensitivity of cells to VP16 were determined. Finally the quiescent state and drug resistance properties of KG1a cells were determined after inhibiting N-cadherin-mediated cell-cell interaction by EGTA treatment. The results showed that the G(0) phase cell ratio in N-cadherin positive KG1a cells was higher than that in N-cadherin negative KG1a cells. After KG1a cells were induced to enter cell cycle, the G(0) phase cell ratio was decreased significantly and the sensitivity of KG1a cells to VP16 increased. Following EGTA treatment for 24 hours, the G(0) phase cell ratio decreased and the drug-sensitivity was enhanced significantly. It is concluded that N-cadherin-mediated adhesion keeps N-cadherin positive leukemia cells in quiescent state of G(0) phase, thus protect these leukemia cells against VP16 chemotherapy.

[The effects of AML1B and AML1/ETO on the transactivation of TSC genes.].

OBJECTIVE: To investigate the effects of AML1B and AML1/ETO fusion gene on the transcription activity of TSC1 and TSC2 promotor and to explore its role in leukemogenesis. METHODS: The luciferase reporter plasmids of TSCs gene promoter containing a AML1 binding site were constructed, and cotransfected into CV-1 cells with AML1B or AML1/ETO expression plasmids separately. The transactivity of TSCs gene promoter was assayed by luminometer. RESULTS: AML1B exhibited a transactivity to TSC2 gene promoter in a dosage-dependant manner, but showed no significant transactivity to TSC1's. The transactivity to TSC2 gene promoter showed 8.55 fold increase as companed with control group at 75 ng of pCMV5-AML/B. AML1/ETO showed a significant transactivity to TSC1, but no transactivity to TSC2's. However, AML1/ETO antagonized the effect of AMLlB to TSC2 gene promoter. CONCLUSION: AML1B and AML1/ETO can regulate the transcription of TSC genes.

[Leukemia cell surface expression of E-cadherin and its correlation with membrane localization of beta-catenin].

OBJECTIVE: To investigate the expression of cell surface E-cadherin in leukemia cell and the correlation of cell membrane localization of beta-catenin with E-cadherin expression. METHODS: Bone marrow samples from 46 patients with acute leukemia and 17 normal donors were analyzed. Cell surface expression of E-cadherin and membrane localization of beta-catenin were labeled by immunofluorescence and analyzed with a laser scanning confocal fluorescence microscope in 14 specimens. RESULTS: Cell surface E-cadherin expression level was significantly lower in leukemia cells (with the median fluorescent intensity of 16.78) than in normal hematopoietic progenitors (26.03). Correlation analysis showed that cell membrane localization of beta-catenin was correlated with E-cadherin expression (r = 0.74, P = 0.002). After E-cadherin was induced to express in leukemic cell by 5-Aza-CdR, membranous expression of beta-catenin was elevated while the nuclear expression reduced, indicating that E-cadherin-mediated adhesions could recruit beta-catenin to cell membrane. CONCLUSION: The loss of E-cadherin in leukemia cells may result in beta-catenin translocating to the nuclear and transcriptional activation of its target genes.