Cytotoxic T Lymphocyte Antigen-4 Down-Regulates T Helper 1 Cells by Increasing Expression of Signal Transducer and Activator of Transcription 3 in Acute Graft-versus-Host Disease.

Numerous previous studies have suggested that cytotoxic T lymphocyte antigen-4 (CTLA-4) plays an important role in acute graft-versus-host disease (GVHD). How CTLA-4 acts in regulating acute GVHD remains unknown, however. In the present study, we found that, compared with healthy controls, CTLA-4 plasma and relative mRNA levels in patients with acute GVHD were initially decreased and then markedly elevated after 28 days of treatment. CTLA-4 levels were higher in patients with grade I-II acute GVHD compared with those with grade III-IV acute GVHD both before and after treatment. Up-regulation of CTLA-4 significantly increased the luciferase activity and degree of phosphorylation of signal transducer and activator of transcription 3 (STAT3). Meanwhile, T cell activation was significantly inhibited, and levels of IFN-γ, IL-17, and IL-22 decreased. These findings suggest that CTLA-4 might be involved in the pathogenesis of acute GVHD, and may down-regulate T helper 1 cells by increasing STAT3 expression in acute GVHD.

Increased expression of T cell immune response cDNA 7 in patients with acute graft-versus-host disease.

Acute graft-versus-host disease (aGVHD) has become the important complication post-allogeneic hematopoietic stem cell transplantation. Abnormally activated T cells might play an important role in the pathogenesis of aGVHD. But its exact mechanism remains poorly understood. T cell immune response cDNA 7 (TIRC7) has been identified to be essential in T cell activation; however, the role of TIRC7 in aGVHD remains unclear. The purpose of this study was to measure the expression of TIRC7 and T helper (Th) cells in patients with aGVHD before and after treatment. We showed that TIRC7 levels in aGVHD patients were higher than those of healthy controls and markedly declined after treatment. The levels of IFN-γ (Th1), IL-17 (Th17), and IL-22 (Th22) were in accordance with the grade of aGVHD. In addition, TIRC7 levels were also associated with the severity of aGVHD. In conclusion, TIRC7 might be involved in the pathogenesis of aGVHD and TIRC7 level might be an indicator to evaluate the response of patients with aGVHD to treatment.

Amino acid residue E543 in JAK2 C618R is a potential therapeutic target for myeloproliferative disorders caused by JAK2 C618R mutation.

Janus kinase 2 (JAK2) is an important mediator of cytokine receptor signaling and plays a key role in the hematopoietic and immune responses. The acquired JAK2 C618R somatic mutation is detected in a subset of myeloproliferative disorders (MPDs) patients and presumed to be a biomarker for MPDs. However, how JAK2 C618R mutation causes MPDs is still unclear. Our results indicate that the amino acid residue E543 in JAK2 C618R is indispensable for its constitutive activation. When the glutamic acid at this position was mutated to alanine (E543A) in the JAK2 C618R, its activity significantly decreased. However when the glutamic acid was mutated to the acidic amino acid, aspartic acid, JAK2 C618R activity changed little. These results suggest that there is an interaction between the amino acid residue R618 and E543, and that this interaction is crucial to sustain the constitutive activation of JAK2 C618R. More importantly, the E543 single mutation had no effects on the function of wild type JAK2 (WT JAK2). This study suggests that the amino acid residue E543 might be a potential target for specific inhibitors to treat MPDs caused by the JAK2 C618R mutation.

Effects of the PLK4 inhibitor Centrinone on the biological behaviors of acute myeloid leukemia cell lines.

Polo-like kinase 4 (PLK4), a key regulator of centriole biogenesis, is frequently overexpressed in cancer cells. However, roles and the mechanism of PLK4 in the leukemiagenesis of acute myeloid leukemia (AML) remain unclear. In this study, the PLK4 inhibitor Centrinone and the shRNA knockdown were used to investigate roles and the mechanism of PLK4 in the leukemiagenesis of AML. Our results indicated that Centrinone inhibited the proliferation of AML cells in a dose- and time-dependent manner via reduced the expression of PLK4 both in the protein and mRNA levels. Moreover, colony formation assay revealed that Centrinone reduced the number and the size of the AML colonies. Centrinone induced AML cell apoptosis by increasing the activation of Caspase-3/poly ADP-ribose polymerase (PARP). Notably, Centrinone caused the G2/M phase cell cycle arrest by decreasing the expression of cell cycle-related proteins such as Cyclin A2, Cyclin B1, and Cyclin-dependent kinase 1 (CDK1). Consistent with above results, knockdown the expression of PLK4 also inhibited cell proliferation and colony formation, induced cell apoptosis, and caused G2/M phase cell cycle arrest without affecting cell differentiation. All in all, this study suggested that PLK4 inhibited the progression of AML in vitro, and these results herein may provide clues in roles of PLK4 in the leukemiagenesis of AML.

[An absence of donor TH17 differentiation ameliorates dermal tissue damage].

OBJECTIVE: To explore the functions of TH17 cell in cutaneous graft-versus-host disease (GVHD). METHODS: A model of acute GVHD (aGVHD) was established with a major histocompatibility complex class I/II-disparate allogeneic bone marrow transplantation (BMT). Bone marrow monocytes and splenic T cells from donor C57/BL6 were enriched. The recipient BABL mice were irradiated ((60)Co source) with 7.5 Gy total body irradiation (TBI) and injected with 5 × 10(6) marrow monocytes and 5 × 10(5) T cells. The experimental mice were divided into 3 groups: lethal total body irradiation (TBI); allogeneic bone marrow transplantation (BMT) and recipients of halofuginone (HF). The symptoms of aGVHD were observed daily and detailed histopathologic analyses of recipient skin were performed at Day 6 post-transplantation. And Tri-color flow cytometry (FCM) was performed at Day 6 post-transplantation to measure the levels of interleukin (IL)-17, interferon (IFN)-γ and TH1/TH17. RESULTS: Clinical GVHD symptoms were observed in recipient mice. The administration of HF to lethally irradiated recipients led to very modest GVHD-induced cutaneous changes manifested predominantly by fur loss. However, the experimental animals receiving only allogeneic BMT showed significant fur loss and pathologic skin conditions. Consistent with the clinical evaluations, the histopathologic results demonstrated significantly increased pathologic cutaneous lesions in recipients undergoing only BMT. The median ratios of TH1/TH17 cells were 17.57 and 5.31 in the HF and BMT groups respectively. The difference had statistical significance (P < 0.05). The serum levels of IL-17 were(1.47 ± 0.18) and (2.81 ± 0.19) pg/ml in the TBI and BMT groups respectively (P < 0.05). But IL-17 could not be detected in the HF group. The serum levels of IFN-γ were (3.86 ± 0.32), (42.97 ± 0.42) and (9.89 ± 0.51) pg/ml in the TBI, BMT and HF groups respectively. The inter-group differences had statistical significance (P < 0.05). CONCLUSION: An absence of TH17 cell may alleviate the cutaneous GVHD but exacerbate the systemic GVHD.

[Effects of pretreatment regimen on mice liver injury in hematopoietic stem cell transplantation].

OBJECTIVE: To investigate the effects of conditioning regimen on mice liver injury during hematopoietic stem cell transplantation. METHODS: Forty healthy 8-10 weeks old female BALB/c mice were randomly divided into control group, non-myeloablative total body irradiation group, myeloablative total body irradiation group, busulfan group and cyclophosphamide group with 8 mice each. The general condition of each mouse was continuously observed. Peripheral white blood cells were counted and pathological changes of liver were examined by hematoxylin and eosin stain under microscope. The ultrastructure changes of hepatocyte and liver vascular endothelium were detected under transmission electron microscope. RESULTS: Compared to control group, each experimental group showed that the count of white blood cells was decreased significantly after conditioning pretreatments (P < 0.05). The conditioning regimen had injury effects on the mice liver in each experimental group. There were various degrees of damage to the hepatocyte and liver vascular endothelium. CONCLUSION: Total body irradiation, Busulfan and Cyclophosphamide all led to the damage of liver vascular endothelium in hematopoietic stem cell transplantation, and may be the important triggers of hepatic veno-occlusive disease.

[Construction of lentiviral vector pTK208-mVEGF-IRES-DsRed contains dsred and mVEGF and its expression in 293T cells].

OBJECTIVE: To construct red fluorescent protein (DsRed) and mouse vascular endothelial growth factor (mVEGF) lentiviral expression vector in order to obtain the DsRed and VEGF expression in 293T cells. METHODS: The mVEGF was amplified from the lungs of fetal mouse by RT-PCR. The IRES-DsRed was obtained from plasmid pLV-tTRKRAB-red which contains IRES-DsRed sequence by PCR. Then they were cloned into lentiviral expression vector pTK-208. Human embryonic kidney 293T cells were co-transfected with the three plasmids by lipofectamine, and the expression of DsRed was examined under fluorescent microscope 24 h and 48 h after transfection. 48 h and 72 h later the viral supernatant was used to infect 293T cells, the expression of DsRed was examined under fluorescent microscope and Western blot assays was used to examine the expression of mVEGF in cells and the culture medium. RESULTS: The recombinant lentiviral vector pTK208-mVEGF-IRES-DsRed was constructed, the virus titres were above 10(6) PFU/mL in the supernatant. After infection, DsRed and mVEGF proteins were successfully expressed in 293T cells. CONCLUSION: The lentiviral vector pTK208-mVEGF-IRES-DsRed contains DsRed and mVEGF were successfully constructed and expressed in 293T cells, it could provide a basis for further researches on the pathophysiological mechanism of VEGF and lay the foundation of gene therapy.

[Effects of Combined Infusion of Mesenchymal Stem Cells and Endothelial Progenitor Cells on Lung Injury after Hematopoietic Stem Cell Transplantation].

OBJECTIVE: To investigate the effects of combined infusion of mesenchymal stem cells (MSC) and endothelial progenitor cells (EPC) on lung injury after hematopoietic stem cell transplantation (HSCT). METHODS: The experiment was divided into normal control group, irradiation group, bone marrow cell transplantation group (BMT group), BMT+EPC group, BMT+MSC group and BMT+EPC+MSC group. The model of HSCT was established, on the 30th day after transplantation, the mice were sacrificed. Then lung tissue was taken for testing. The mRNA expression levels of VEGF, IL-18, IL-12b were detected by RT-PCR, and protein expression level of NLRP3 was detected by Western blot. The expression of MPO and CD146 was observed by immunohistochemistry assay. RESULTS: The expression level of VEGF gene in BMT+EPC+MSC group was significantly higher than that in other groups (P＜0.01). The expression level of IL-18 and IL-12b gene was the highest in BMT group and the lowest in BMT+EPC+MSC group, and the difference was statistically significant (P＜0.05). HSCT could increase the expression of NLRP3 protein, and the BMT+EPC+MSC could significantly reduce the level of NLRP3 protein in lung cells, tending to normal. Compared with normal tissues, the BMT+EPC+MSC could improve the lung tissue structure more effectively, the expression of MPO positive cells was lower, and the expression of VEGF positive cells was higher. CONCLUSIONS: The combined infusion of MSC and EPC can promote capillary regeneration, alleviate inflammation and promote lung repair after HSCT, which is superior to single EPC or MSC infusion.

[Construction and expression of the self-inactivating lentiviral vector containing Murine Foxp3 gene].

OBJECTIVE: To construct the self-inactivating lentiviral vector containing murine Foxp3 gene and detect its expression in the CD4+ CD25- T cells. METHODS: The bicistronic lentiviral transfer plasmid containing Foxp3 gene and internal ribosomal entry site-green fluorescent protein gene (IRES-GFP) was constructed. Human embryonic kidney 293T cells were co-transfected by lentiviral packing system, which including the packaging plasmid deltaNRF, the transfer plasmid and the envelope plasmid VSVG using liposome. Then manifested the efficiency of gene transduction with Flow Cytometry (FCM) and the expressions of Foxp3 mRNA and protein were assayed by RT-PCR and Western blotting. RESULTS: The lentiviral transfer plasmid pXZ208-Foxp3-IRES-GFP was constructed, the virus titres were above 10(6) IU/mL in the supernatant. After coculture with thus cells, the CD4+ CD25- T cells in experimental group expressed significantly higher amounts of Foxp3 mRNA and protein than control group, and the efficiency of gene transduction was about 55.95%. CONCLUSIONS: The self-inactivating lentiviral vector containing murine Foxp3 gene are successfully constructed. This gene delivery system can transduce Foxp3 gene into CD4+ CD25- T cells with highly efficient expression.

[Irradiation-induced homing of donor endothelial progenitor cells in mice allo-HSCT model].

OBJECTIVE: To investigate the effect of allo-HSCT irradiation preconditioning on the homing of donor endothelial progenitor cells (EPCs). METHODS: The mononuclear cells were collected form mice bone morrows, then cultured in EGM-2 medium. The cells were identified after 5-7 days and were labeled with CFSE. The mice were divided randomly into four groups, control, EPCs transplantation, irradiation, and irradiation EPCs transplantation. The circulating ECs, circulating EPCs and CFSE positive cells in the peripheral blood, spleen and bone morrows of the mice were measured by FCS. The histological examination, electron microscope and immunofluorescence analyses of those tissues were also performed. The distribution of labeled EPCs was observed. RESULTS: The cells were identified as CD45low, CD133+ CD31+, Dil-ac-LDL+. The number of those cells in the irradiation group increased gradually after preconditioning and reached peak at day 3 or 5 and sustained the peak level for 2 days, which was significantly different from the control (P < 0.05). Under the light microscopy and TEM, damaged endothelium was detected. In the irradiation and EPCs transplantation groups, CFSE labeled cells increased and reached peak at 18 hours, and then decreased till 72 hours. Green fluorescent cells were observed in different tissues at different times, and the strongest fluorescence intensity occurred at 36 hours. CONCLUSIONS: The EPCs can be induced from mice bone morrow mononuclear cells, with expressed phenotypic characterization. Irradiation in transplantation preconditioning can cause severe endothelium injury, which can start the mobilization of EPCs. The endothelium injury can induce extrinsic EPCs homing to the tissues which are badly injured. Endothelial progenitor cells

Loss of K607 and E877 interaction is a key reason for JAK2 K607N mutation caused acute myeloid leukemia.

Oncogenic activation of tyrosine kinase signaling pathway is recurrent in human leukemia. The acquired Janus kinase 2 (JAK2) K607N somatic mutation was detected in about 6.8% of acute myeloid leukemia (AML) patients. However, roles of JAK2 K607N mutation in the leukemogenesis of AML remain unclear. In this study, loss of interaction between K607 and E877 was identified as key reasons for JAK2 K607N mutation constitutive activation. JAK2 K607N and mutations (K607A, K607G and E877A) abolished the K607 and E877 interaction caused JAK2 constitutive activation. While, mutations (K607R, E877D) repairing this interaction reduced K607N mutation's activity. Furthermore, our studies showed that disruption of K607 and E877 interaction abolished JH1/JH2 domains' interactions and led to JAK2 constitutive activation. More importantly, JAK2 K607N and mutations disrupted this interaction enhanced JAK2-STAT5 pathway activation and the proliferation of Ba/F3 cells. Thus our studies provide clues in understanding the leukemogenesis of JAK2 K607N mutation in AML.

[Effect of Stably Down-regulating FMI Expression of K562 Cells on Sensitivity of K562 cells to Imatinib Mesylate].

OBJECTIVE: To investigate the effect of stably down-regulating the FMI expression of K562 cells on the sensitivity of K562 cells to Imatinib (IM) and its possible mechanism. METHODS: Western-blot was used to detect the expression of FMI protein in K562 cells and peripheral blood mononuclear cells from the patients with chronic myelogenous leukemia, chronic myeloid blast crisis and healthy volunteers. The specific interference sequences targeting at the human FMI gene were designed and ligated into the lentiviral vector LV3; the three plasmid system-packaged lentivirus particles were used to transfect K562 cells to screen K562 cells that stably down-regulated FMI. CCK-8 assay and flow cytometry were used to determine effect of IM on cell proliferation and apoptosis. The transcription level of FMI and Fz8 in leukemia cells was detected by fluorescent quantitative PCR. The protein expression levels of FMI, Fz8, NFAT1, BCR-ABL and ß-catenin in leukemia cells were detected by Western-blot. RESULTS: The expression of FMI protein could be detected in peripheral blood mononuclear cells of the patients with CML-BC and K562 cells, the FMI expression could not be detected in all the patients with CML-CP and healthy volunteers. The recombinant lentiviral vector LV3/FMI had been successfully constructed the lentivirus was packaged, and the K562 cells stably down-regulating the FMI protein were screened. After stable down-regulation of FMI expression in K562 cells, the proliferation rate of leukemia cells decreased and the apoptosis rate was increased under the same drug concentration. Both the transcription and protein expression levels of Fz8 decreased. The NFAT1 total protein level increased, as well as the nuclear translocation of protein was enhanced. There was no significant change in the expression level of BCR-ABL fusion protein. The expression level of ß-catenin protein decreased. CONCLUSION: After the stable down-regulation of FMI expression, the sensitivity of K562 cells to IM and apoptosis of cells increase, which are performed possibly by inhibiting the FMI-Fz8 signaling pathway and activating the Ca2+-NFAT and Wnt/ß-catenin signaling pathway.

[Role of Ca2+-NFAT Signaling Pathway in Ph+ ALL Drug-resistance Mediated by Bone Marrow Stromal Cells].

OBJECTIVE: To explore the role of Ca2+-NFAT signaling pathway in Ph+-ALL drug resistance mediated by bone marrow stromal cells. METHODS: The transcription level of NFAT mRNA in Sup-B15 cells and Ph+ ALL primary cells was detected by polymerase chain reaction. The expression of P-glycoprotein in Sup-B15 cells was detected by flow cytometry. The change of NFAT protein in Sup-B15 cells was detected by Western blot. AnnexinV/7-AAD was used to label cells. Flow cytometry was used to detect cell apoptosis; Fluo 3-AM dye was used to label cells, and flow cytometry used to detect changes of Ca2+ concentration in leukemia cells. RESULTS: NFAT expression could be detected in both Sup-B15 and Ph+ ALL primary cells; P-glycoprotein could not be detected by flow cytometry; CAS could significantly inhibit NFAT protein expression in clinically applied drug concentrations (2.5, 5 µmol/L); Clinically applied concentration of CAS (2.5, 5 µmol / L) has no significant effect on the apoptosis of Sup-B15 cells, while higher concentration of CAS (10 µmol / L) could induce apoptosis of Sup-B15 cells. Bone marrow stromal cells OP9 could, decrease the sensitivity of Sup-B15 cells and Ph+ ALL primary cells to imatinib (IM); After co-culture with bone were marrow stromal cells, the Ca2+ concentration in Sup-B15 cells was enhanced, the levels of NFAT protein and nullear protein in sup-B15 cells also were enhanced. The addition of CAS in co-culture system could inlibit the Ca2+-NFAT signaling pathway, reduce the protective effect of OP9 on Sup-B15 cells.Conclution:The Ca2+-NFAT sigualing pathway, contributes to the survival of Ph+ ALL cells. Bone marrow stromal cells can mediate the resistance of Ph+ ALL cells to IM by activating Ca2+-NFAT signaling pathway.

Disruption of R867 and Y613 interaction plays key roles in JAK2 R867Q mutation caused acute leukemia.

Janus tyrosine kinase 2 (JAK2) mediates downstream signaling of cytokine receptors in all hematological lineages, constitutively active somatic JAK2 mutations were important for the leukemogenesis of acute leukemia (AL). The JAK2 R867Q somatic mutation is detected in a subset of AL patients. However, roles of JAK2 R867Q mutation in the pathogenesis of AL remain unclear. In this study, homology modeling analysis showed that loss of interaction between R867 and Y613 disrupted the JAK2 JH1/JH2 domain's interactions was responsible for its activation. JAK2 R867Q and mutations (R867A and R867G) abolished this interaction caused JAK2 constitutive activation. While, mutations (R867K, Y613E, R867K/Y613E) repairing this interaction reduced JAK2 R867Q mutation's activity. Furthermore, our studies showed that abolished R867 and Y613 interaction disrupted JH1/JH2 domains' interactions and led to JAK2 constitutive activation. More importantly, mutations (R867Q, R867A and R867G) disrupted this interaction enhanced the activity of JAK2-STAT5 pathway and the proliferation of Ba/F3 and MV4-11 cells. Further study showed that JAK2 R867Q mutation promoted the expression of proliferation marker and inhibited the differentiation marker of Ba/F3 and MV4-11 cells. Thus our studies provide clues in understanding the pathogenesis of JAK2 R867Q mutation in AL.

Roles of T875N somatic mutation in the activity, structural stability of JAK2 and the transformation of OCI-AML3 cells.

Activating mutations in JAK2 have been described in patients with various hematologic malignancies including acute myeloid leukemia (AML) and myeloproliferative neoplasms. However, mechanism of these mutations in JAK2's activity, structural stability and pathology of AML remains poorly understood. The JAK2 T875N somatic mutation has been detected in about 5.2% of AML patients. But the structural basis and mechanism of JAK2 T875N mutation in the pathology of AML is still unclear. Our results suggested that JAK2 T875N mutation disrupted the T875 and D873 interaction which destroyed the compact structure of JH1 domain, forced it into the active conformation, facilitated the entrance of substrate and thus led to JAK2 hyperactivation. Mutations (T875N, T875A, D873A and D873G) disrupted the T875 and D873 interaction enhanced JAK2's activity, decreased its structural stability and JH2 domain's activity which further enhanced JAK2's activity, while mutations (T875R, D873E, T875R/D873E) repaired this interaction displayed opposite results. Moreover, JAK2 T875N mutation enhanced the activity of JAK2-STAT5 pathway, promoted the proliferation and transformation of OCI-AML3 cells. This study provides clues in understanding structural basis of T875N mutation caused JAK2 hyperactivation and its roles in the pathology of AML.

[Relationship between NLRP1 and Liver Dysfunction Following Allogeneic Hematopoietic Stem Cell Transplantation].

OBJECTIVE: To explore the effect of NLRP1 on the liver dysfunction following allogeneic hematopoietic stem cell transplantation(allo-HSCT). METHODS: The mouse model of allo-HSCT was established by using C57BL/6 and NLRP-/- mice were used as the recipients: BABL/c mice were used as donors). The chimera rates of donor's bone marrow cells were assayed by flow cytometry. ALT and AST levels were measured by automatic biochemical analyzer. Western blot was used to detect the expressions of NLRP1, the precursor of Caspase-1 and its active segment p20,IL-1ß,IL-18 and MPO in livers. RESULTS: The chimera rate was over 96% on the day 14 after allo-HSCT, and showed that the hematopoietic stem cells of donors had been transplanted into recipients. ALT and AST levels were increased from (173.9±12.39)U/L and (283.7±28.00)U/L on day 7 to (3902±1745)U/L and (5316±924)U/L on the day 14 and decreased to (3153±564.4) U/L and (4350±957.7) U/L on the day 28, respectively. Western blot showed that the expression of NLRP1 was increased after allo-HSCT, which displayed a similar trend with the changes of ALT and AST. When knocking out NLRP1, the contents of ALT and AST in the knocked group were significantly decreased in comparison with the group without knocking out. And the expression levels of NLRP1 related inflammatory proteins, precursor of Caspase-1,p20,Mature-IL-1ß,Mature-IL-18 and MPO were lower than those in groups without knocking out NLRP1 gene. CONCLUSION: Allo-HSCT can cause the damage of liver function and increase the expression of NLRP1, while knocking out NLRP1 can reduce the damage of liver function, so NLRP1 may be one of the important factors leading to liver dysfunction.

Effect of flight transport stress on blood parameters in beagles and the anti-stress effect of dangshen.

BACKGROUND: This study investigated the effect of flight transport stress on beagles' routine blood indexes and biochemical parameters and evaluated the anti-stress effect of dangshen (Codonopsis pilosula). METHODS: We selected 12 beagles and divided them into two groups. One group was treated with dangshen decoction two hours before the flight, and the other group was untreated. Their routine blood indexes and clinical biochemical parameters were tested and analyzed before transport, after unloading and after adaptation for 1, 2, 3, 4, 5, and 6 days after administering dangshen. RESULTS: We found that flight transportation stress adversely influenced many of the beagles' routine blood indexes. These recovered during adaptation, with dangshen administration assisting recovery of most indexes. Flight transport stress also adversely influenced biochemical indexes in the beagles. Again these recovered during adaptation, and dangshen aided in the recovery. CONCLUSION: Thus, we found that flight transport adversely affected the beagles' blood indexes, and dangshen reversed the damage from transport stress.

Roles of amino acid residues H66 and D326 in the creatine kinase activity and structural stability.

Creatine kinase (CK) is a key enzyme for cellular energy metabolism, catalyzing the reversible phosphoryl transfer from phosphocreatine to ADP in vertebrates. CK contains a pair of highly conserved amino acids (H66 and D326) which might play an important role in sustaining the compact structure of CK by linking its N- and C- terminal domains; however the mechanism is still unclear. In this study, spectroscopic, structural modeling and protein folding experiments suggested that D326A, H66P and H66P/D326A mutations led to disruption of the hydrogen bond between those two amino acid residues and form the partially unfolded state which made it easier to be inactivated and unfolded under environmental stresses, and more prone to form insoluble aggregates. The formation of insoluble aggregates would decrease levels of active CKs which may provide clues in CK deficiency disease. Moreover, these results indicated that the degree of synergism had closely relationship to the conformational changes of CK. Thus, our results provided clues for understanding the mechanism of amino acid residues outside the active site in regulating substrate synergism.

[Effect of Steadily Down-regulating VE-Cadherin Expression on Susceptibitity of K562 Cells to Chemotherapy].

OBJECTIVE: To investigate the effect of steadily down-regulating the expression of VE-cadherin on the chemotheraputic sensitivity of K562 cells, and explore its possible mechanism. METHODS: Specifically targeting interference sequences carrying human VE-cadherin were designed, the recombinant lentiviral vector containing the IRES-GFP and NEO segment was constructed; recombinant lentivirus was generated by three-plasmids packing system, and transfected into K562 cells, then the cells steadily down-regulated were sorted. CCK-8 assay was performed to evaluate the VE-cadherin of chemotherapeutic (Imatinib) sensitivity of K562 cells. The apoptosis was analyzed by flow cytometry with Annexin V/7-AAD double labeling. The expressions of CD133 and ALDH1 mRNA were determined by real time PCR. The protein expressions of VE-cadherin, BCR-ABL and ß-catenin were analyzed by Western blot. RESULTS: The recombinant lentiviral vector pLB-shVEC-NEO-IRES-GFP was successfully constructed, packed into the lentivirus, then the K562 cells steadily down-regulating VE-cadherin expression was obtained. When VE-cadherin was down-rengulated in K562 cells, the proliferation rate was reduced while the the apoptosis rate was increased; the mRNA levels of CD133 and ALDH1 also were reduced; BCR-ABL fusion protein was not obviously changed; the total ß-catenin protein, as well as the nuclear ß-catenin protein were decreased in the K562/shVEC cells. Conclution: K562 cells are more susceptible to chemotherapy when VE-cadherin is down-regulated, that may be realized via reducing the stability and the nuclear transfer of ß-catenin protein.

[Relationship between BCR-ABLIS and Prognosis and Affecting Factors for Prognosis in CML Patients Treated with TKI for 12 Months].

OBJECTIVE: To evaluate the long-term prognosis of CML patients whose BCR-ABL transcript level was warning and best response at 12 months of treatment with tyrosine kinase inhititor (TKI), and to investigate the factors affecting therapeutic efficacy and prognosis. METHODS: The clinical data of patients with newly diagnosed CML were analyzed retrospectively. According to BCR-ABL transcript level, the 80 patients were divided into group A and group B, the patients with BCR-ABLIS >0.1% and ≤ 1% (warning response) were entolled in group A, and the patients with BCR-ABLIS ≤ 0.1% (best response) were enrolled in group B as control. The ratio of patients with main molecular response (MMR) and deep molecular response (DMR), as well as aquistation rate and cummulative rate of MR4 (DMR) at specified fine points in 2 groups were compared, the independent risk factors affecting the therapeutic efficacy and prognosis were analyzed. RESULTS: The MMR and MR4 of the B group at 15, 18 and 24 months after TKI treatment were significantly higher than those of the A group, and the patients in the B group reached MR4 faster. In the 3 months, 6 months and 12 months after the demarcation point (TKI 12 months), the A group was much less easy to obtain MR4 (P<0.05) than the B group. Through survival analysis, there were more patients in the B group than the A group at different time points to reach MR4, and the difference was statistically significant (P<0.01). The single factor analysis showed that the splenomegaly (below rib edge)> 10cm (P<0.01) and lactate dehydrogenase > 400 U/L (P<0.05) were the long-term warning factors for patients. Multivariate analysis showed that the size of the spleen was an independent factor (P<0.01) to affect the prognosis of the patients who had been warned for 12 months. CONCLUSION: Patients at 12 months warning effect are slower and less easier to get DMR, which has a poor long-term prognosis. The size of the spleen in the patient at warning for 12 months of treatment effect can predict the relatively poor long-term prognosis. For a patient with a 12 months response to the warning, an early replacement therapy is available on the basis of combining other factors..