Preparation of Core-Shell Silver Nanoparticles@Mesoporous Silica Nanospheres with Catalytic Activities.

Core-shell silver nanoparticles@mesoporous silica spherical nanoparticles (Ag NPs@MSNs) were prepared by a two-step method. First, Ag NPs were synthesized by chemical reduction using silver nitrate (AgNO3) as the precursor, cetyl trimethyl ammonium bromide (CTAB) as the stabilizer, and sodium borohydride (NaBH4) as the reductant. Then, MSNs were obtained by employing CTABstabilized Ag NPs as the template and hydrolyzing tetraethoxysilane (TEOS) precursor in the presence of the alkaline precipitant, triethanolamine (TEOA). The effects of different preparation routes (core-first vs. shell-first), type of reductants as well as extraction methods and agents were studied. The obtained core-shell NPs were characterized by infrared spectroscopy (IR) and transmission electron microscopy (TEM). Our results showed that the core-first route was viable to produce uniform Ag NPs@MSNs with ordered mesostructures. Afterwards, those NPs were used as the catalyst to catalyze the reduction of rhodamine, a model dye compound representing organic pollutants in waste water, in the presence of NaBH4. It was found that Ag NPs@MSNs not only were efficient catalysts but also participated as coreductants in the reaction. Moreover, they exhibited almost no loss of catalytic efficacy after several reduction cycles, which indicated their promising future use as efficient recyclable catalysts for organic pollutant treatments.

Fentanyl inhibits the invasion and migration of colorectal cancer cells via inhibiting the negative regulation of Ets-1 on BANCR.

BACKGROUND: Recent studies have shown the potential anti-tumor effect of fentanyl on colorectal cancer (CRC). However, its underling mechanism is still unclear. Since studies indicates the abnormal expression of transcription factor Ets-1 and BRAF-activated lncRNA (BANCR) in CRC progress, the relationship between Ets-1 and BANCR was investigated here to illustrate the fentanyl-induced mechanism on CRC in vitro. METHODS: The expression levels of Ets-1 and BANCR were first detected in fentanyl-treated CRC cells. The interaction between Ets-1 and BANCR promoter was verified with chromatin immunoprecipitation assays, as well as corresponding acetylation of histones. The regulation of Ets-1 on BANCR expression was confirmed through luciferase assays and RT-PCR analysis. And, cell clone formation, cell migration and invasion were observed to evaluate the anti-tumor effects of fentanyl. Ets-1 overexpression or co-overexpression with BANCR was further performed by plasmids transfection to show the regulatory role of Ets-1 in fentanyl-induced mechanism. RESULTS: Fentanyl induced BANCR upregulation and Ets-1 downregulation in CRC cells. Further studies showed that Ets-1 negatively regulated BANCR expression via the deacetylation of histones H3 within BANCR promoter. Moreover, fentanyl induced less cell clone formation, as well as inhibited cell migration and invasion in vitro, while Ets-1 overexpression inhibited fentanyl-induced effects that could be reversed by BANCR co-overexpression. CONCLUSION: Fentanyl showed anti-tumor like effects on CRC cells, including less cell clone formation and inhibited cell migration and invasion. Furthermore, the regulatory role of Ets-1 on BANCR influenced fentanyl-induced mechanism, indicating their potential application in the therapeutic treatment of CRC.

Study on blocking the leukemia immune escape after BMT by Fas-Fas ligand pathway.

BACKGROUND: To investigate if bone marrow transplantation (BMT) with bone marrow mononuclear cells (BMMCs) transducted with murine soluble Fas gene (sFas) using adenovirus vector could block the immune escape of leukemia cells eliminate the residual leukemia cells and reduce their relapse. METHODS: The recombinant adenovirus vector with murine sFas, adsFas, and the control vector adEGFP were constructed using homologous recombination between two plasmids in Escherichia coli. BMT was carried out after the BMMCs were infected with Adenoviruses. The mice models of leukemia/lymphoma were constructed by inoculating female C57BL/6 mice (H-2b) with 10(5) EL4 cells/mouse through caudal vein. Donors of bone marrow grafts were syngeneic male mice. BMMCs were infected with AdsFas or AdEGFP 24 hours before (Group D or E). The following three groups were simultaneously used: Group A, no BMMCs transplanted; Group B, transplanted with BMMCs not infected with adenoviruses; Group C, only transfusing EL4 cells, neither irradiation nor BMT. The hematopoietic reconstitution, generation of leukemia/lymphoma and the survival rate were observed in all groups after BMT. RESULTS: The adenovirus vectors were successfully constructed. The titre of virus after purification was up to 2.5 x 10(11) pfu/ml. Spleen indices examined 11 days after BMT were not obviously different among Group B, D and E (P > 0.05), but indices in Group A were significantly lower than those in the latter three groups (P < 0.01). Counts of leukocytes and platelets on +30 day showed mice were reconstituted satisfactorily in Group B and D, but very low in Group C and E. The Y-chromosomes existed 2 months after BMT and examination of bone marrow cytology showed that Group B and D were almost normal, but Group C and E had plenty of lymphoblast-like tumor cells. Tumors were obviously observed in the mice of Group C and E by histopathological examination, but the mice in Group B and D were normal. The survival rates were 0 (0/4) in Group A, 100% in Group B (6/6) and D (16/16), 12.5% (2/16) in Group C and 6.25% (1/16) in Group E respectively. It is demonstrated that, in contrast with the control (Group EGFP), survival rate was significantly increased in the sFas Group (P < 0.01). CONCLUSIONS: The transfer of sFas gene by adenovirus changed the prognosis state of leukemia/lymphoma mice after auto-BMT. The transduction of sFas might block the effect of the immune escape of EL4 cells through FasL. These results could thus provide a new direction to find a way to treat the leukemia and its recurrence after BMT.

[Experimental study on blocking immune escape of leukemia cells in the recipient after bone marrow transplantation].

OBJECTIVE: To investigate whether murine soluble Fas gene transfected marrow graft could block the immune escape of leukemia cells, so as to eliminate the residual leukemia cells and reduce relapse after bone marrow transplantation (BMT). METHODS: The murine leukemia/lymphoma models were established by inoculating female C57BL/6 mice (H-2b) with 10(5) EL4 cells/mouse through caudal vein. Donors of BM grafts were C57BL/6 male mice. Bone marrow mononuclear cells (BMMCs) were transfected with sFas or EGFP by adenovirus (adsFas or adEGFP) 24 hours before BMT (group D or E). The following three groups were set simultaneously: group A, no BMMCs transplanted; group B, BMMCs transplanted with no adenoviruses transfection; group C, EL4 cells transfusion only. Hematopoietic reconstitution, generation of leukemia/lymphoma and the survival rate were observed in all the groups after BMT. RESULTS: The spleen indices examined 11 days after BMT were not obviously different among group B, D and E (P > 0.05), but in group A were significantly lower than those in the groups B, D, E (P < 0.01). The leukocyte and platelet counts on day 30 after BMT were recovered in group B and D, but were very low in group C and E. The Y-chromosomes appeared 2 months after BMT. Bone marrow pictures in group B and D were almost normal, but in group C and E had plenty of lymphoblast-like tumor cells. Tumors were obviously revealed in the mice of group C and E by histopathology examination, but did not in group B and D. The survival rate was 0 in group A, 100% in group B and D, 12.5% in group C and 6.25% in group E. Compared with that in group E, the survival was significantly increased in the sFas group (P < 0.01). CONCLUSIONS: Graft transfected with sFas gene prolonged the post-BMT survival of leukemia/lymphoma mice. The transfection of sFas might block the effect of the immune escape of EL4 cells through FasL.

[FasL-cDNA transfected into mouse bone marrow cells ex vivo to prevent graft versus host disease].

To explore the new approach to prevent graft versus host disease (GVHD) by purging ex vivo T lymphocytes of bone marrow graft through Fas-FasL way, FasL-cDNA was transfected into BALB/c mouse bon e marrow cells by liposome ex vivo. The transfected cells were cultured together with BAC (BALB/c x C57BL/6) mouse bone marrow graft. The mixing bone marrow graft was infused into BALB/c mouse recipients after 60Co-gamma irradiation. The mortality, manifestation and pathologic change of GVHD in recipient mice were observed. The CFU-S and Y chromosome from donor mice were detected. The results showed that compared with control group, the mortality in 60 days of the recipients in the experimental group decreased (20% vs 70%, P < 0.01) and the morbidity of GVHD lowered (40% vs 100%, P < 0.01). The CFU-S counts for all groups were at normal level on 20 days after transplantation. The Y chromosome from donor mice was discovered in 70% bone marrow nucleated cells of recipient mice survived over 2 months in the experimental group. It is concluded that mFasL-cDNA transfected mouse bone marrow cells prevent GVHD after culturing together with bone marrow graft, and accelerate hematopoietic reconstitution in recipient mice.

[Study on blocking the tumor immune escape by Fas ligand pathway].

The expression of Fas ligand (FasL) on the membrane of many kinds of leukemia or solid tumor cells played an important role in the immune escape of tumor cells. This study was aimed to know if the soluble Fas (sFas), expressed by adenovirus, could block the immune escape of tumor cells by FasL pathway. The two recombinant adenoviral vectors, AdsFas with murine soluble Fas gene and AdEGFP with enhanced GFP protein gene, were constructed by homologous recombination between two plasmids in Escherichia coli with the AdEasy adenovirus vector system. The viruses were propagated and purified by two times ultracentrifugation. Their titres were detected by plaque assays. The expressed protein was evaluated by Western blot analysis. Then the tumor EL4 cells were infected with AdsFas and AdEGFP respectively. The apoptosis ratio of the target cells-YAC-1 cells induced by EL4 cells was respectively detected by (3)H-thymidine ((3)H-TdR) labeling. The results showed that the recombinant adenoviral vectors AdsFas and AdEGFP were successfully obtained. The titres of viruses purified by two times ultracentrifugation were up to 10(11) pfu/ml by plaque assays. The sFas protein was highly expressed in the target cells by Western blot analysis. After the EL4 cells were transfected with the adenoviruses AdsFas, the apoptosis rate of YAC-1 cells in the sFas transfection group (respectively 6%, 7% and 9% when the effector:target (E:T) was 3:1, 10:1 and 30:1) was obviously lower than that in the control group (respectively 28%, 37% and 45%), P < 0.01. But when the EL4 cells were transfected with AdEGFP, the apoptosis rate of YAC-1 cells (respectively 30%, 36% and 48%) was similar to the control group, P > 0.05. In conclusion, the transfer of sFas by adenovirus could inhibit the apoptosis of Fas(+) cells-YAC-1 cells induced by tumor EL4 cells. It showed that the transduction of sFas could block the effect of the immune escape of EL4 cells through FasL in vitro. These results thus provide a new direction to find a way to treat tumors.

[Study on expression and function of fas ligand in human myeloid leukemia cells].

To determine whether the Fas receptor-Fas ligand (FasR-FasL) system, which triggers apoptosis in sensitive cells, is an important mechanism of cytotoxicity in myeloid leukemia. FasL expression was investigated in myeloid leukemia cells and its upregulation by a combination of IL-2 and INF-gamma, +/- as well as its function of inducing Jurkat cells to apoptosis mainly by flow cytometry (FCM). Results showed that leukemia cells expressed more FasL (3.59 +/- 1.05)% than that expressed in the healthy individuals (0.36% +/- 0.16)%, P < 0.001 and the FasL was upregulated (7.78 +/- 3.40)%, P < 0.01 when treated with IL-2 and IFN-gamma. Leukemia cells were co-cultivated with Jurkat cells for 24 hours. Then Jurkat cells were labeled with FITC-annexin V and PE-CD3 to assess apoptosis by FCM. The leukemia cells, which had been incubated with IL-2 and IFN-gamma, induced more Jurkat cells to apoptosis than the ones that freshly isolated from the peripheral blood mononuclear cells, which raised the figure from (8.28 +/- 1.61)% to (10.73 +/- 2.16%). And the supernatant derived from the former killed more Jurkat cells than the latter. It was concluded that human myeloid leukemia cells expressed high levels of functional FasL that can kill Jurkat T-cells by apoptosis. FasR-FasL sys tem could play a role in the "immune escape" and relapse of the leukemia. The induction of apoptosis through the Fas pathway might be a novel and effective approach for leukemia immunotherapy.

[Retroviral vector-mediated in vitro expression of human soluble fas].

Leukemic cells from patients expressed high level FasL cause apoptosis of autologous activated T cells via the Fas/FasL pathway. To investigate the role of soluble Fas (sFas) in reversing this process, a retroviral-mediated expression vector pLXIN-sFas was established. A retroviral-mediated expression system of human sFas was established in vitro and the biological activity of the expression product sFas was observed. To obtain the soluble Fas cDNA, the specific part of the full-length Fas cDNA was deleted by multiple PCR. After pLXIN-sFas packaged by PA317 cells, it was transferred into the target cell COS-7. The quantity of the sFas was (2.2 +/- 0.7) micro g/ml in supernatant of cultured COS-7 cells, and it could greatly inhibit apoptosis of Jurket cells induced by anti-Fas antibody. Our results suggested that the recombinant is able to express the target proteins in vitro and it has the perfect biological activity.