Comparative study of first-principles approaches for effective Coulomb interaction strength Ueff between localized f-electrons: Lanthanide metals as an example.

As correlation strength has a key influence on the simulation of strongly correlated materials, many approaches have been proposed to obtain the parameter using first-principles calculations. However, a comparison of the different Coulomb strengths obtained using these approaches and an investigation of the mechanisms behind them are still needed. Taking lanthanide metals as an example, we research the factors that affect the effective Coulomb interaction strength, Ueff, by local screened Coulomb correction (LSCC), linear response (LR), and constrained random-phase approximation (cRPA) in the Vienna Ab initio Simulation Package. The Ueff LSCC value increases from 4.75 to 7.78 eV, Ueff LR is almost stable at about 6.0 eV (except for Eu, Er, and Yb), and Ueff cRPA shows a two-stage decreasing trend in both light and heavy lanthanides. To investigate these differences, we establish a scheme to analyze the coexistence and competition between the orbital localization and the screening effect. We find that LSCC and cRPA are dominated by the orbital localization and the screening effect, respectively, whereas LR shows the balance of the competition between the two factors. Additionally, the performance of these approaches is influenced by different starting points from the Perdew-Burke-Ernzerhof (PBE) and PBE + U, especially for cRPA. Our results provide useful knowledge for understanding the Ueff of lanthanide materials, and similar analyses can also be used in the research of other correlation strength simulation approaches.

Increasing plasmid-based DNA vaccine construct (16 kb pSVK-HBVA) production in Escherichia coli XL10-Gold through optimization of media component.

At present, there are production processes to produce protein by Escherichia coli (E. coli) fermentation. Research on the design and optimization of the plasmid fermentation medium, however, is less advanced. The fermentation medium that is optimized for plasmid DNA production is different from the medium that is optimized for protein production. So, establishing a scientific and rational method to optimize the fermentation medium used for plasmid production is very important. Previously, our laboratory developed a novel therapeutic DNA vaccine (named pSVK-HBVA) for hepatitis B based on the alphavirus replicon, and found that E. coli XL10-Gold was the optimal host strain for the production of plasmid pSVK-HBVA. The aim of this study was to establish a scientific and rational method to optimize the fermentation medium used for plasmid production, and investigate the effect of growth medium composition on the production of plasmid pSVK-HBVA harboured in E. coli XL10-Gold, as well as to optimize the medium composition. The one-factor-at-a-time experiments demonstrated that Luria-Bertani (LB) was the optimal basic medium. The optimal carbon source and nitrogen source were glycerol and home-made proteose peptone, respectively. Based on the Plackett-Burman (PB) design, proteose peptone, glycerol and NH4Cl were identified as the significant variables, which were further optimized by the steepest ascent (descent) method and central composite design. Growth medium optimization in 500-mL shake flasks by response surface methodology resulted in a maximum volumetric yield of 13.61 mg/L, which was approximately 2.5 times higher than that obtained from the basic medium (LB).

Preparation and characterization of polymeric nanoparticles for siRNA delivery to down-regulate the expressions of exogenous and endogenous target genes.

Gene silencing induced by RNA interference using small interfering RNA (siRNA) provides a promising therapeutic approach for cancers. However, the lack of siRNA delivery vector has limited the development of siRNA therapy. The purpose of this study was to use the novel copolymer (mPEG5k-PCL1.2k)1.4-g-PEl10k to prepare siRNA-loaded nanoparticles for siRNA delivery. The results suggested that (mPEG5k-PCL1.2k)1.4-g-PEl10k could load siRNA to form nanoparticles with particle size less than 200 nm in a narrow distribution. Moreover, a certain density of positive charge existed onto the surfaces of nanoparticles. MTT assay results demonstrated that (mPEG5k-PCL1.2k)1.4-g-PEl10k/siRNA nanoparticles showed very low cytotoxicity. The gene silencing efficiency of (mPEG5k-PCL1.2k)1.4-g-PEl10k/siRNA nanoparticles was investigated through luciferase reporter gene assays. The expression of exogenous luciferase gene was significantly downregulated at a range of N/P ratio from 50 to 125, and was maximally inhibited at the N/P ratio of 125 with 54% and 59% reduction in MCF-7 and HepG2 cells, respectively. In the 4T1-luc cell line expressing luciferase stably, the silencing of endogenous luciferase gene also has a similar overall profile with maximal 54% reduction of luciferase expression. These results suggested that (mPEG5k-PCL1.2k)1.4-g-PEI10k/SiRNA nanoparticles could serve as a kind of highly efficient siRNA delivery system for down-regulating the expression of exogenous and endogenous target genes.

Apigenin inhibits proliferation and induces apoptosis in human multiple myeloma cells through targeting the trinity of CK2, Cdc37 and Hsp90.

BACKGROUND: Multiple myeloma (MM) is a B-cell malignancy that is largely incurable and is characterized by the accumulation of malignant plasma cells in the bone marrow. Apigenin, a common flavonoid, has been reported to suppress proliferation in a wide variety of solid tumors and hematological cancers; however its mechanism is not well understood and its effect on MM cells has not been determined. RESULTS: In this study, we investigated the effects of apigenin on MM cell lines and on primary MM cells. Cell viability assays demonstrated that apigenin exhibited cytotoxicity against both MM cell lines and primary MM cells but not against normal peripheral blood mononuclear cells. Together, kinase assays, immunoprecipitation and western blot analysis showed that apigenin inhibited CK2 kinase activity, decreased phosphorylation of Cdc37, disassociated the Hsp90/Cdc37/client complex and induced the degradation of multiple kinase clients, including RIP1, Src, Raf-1, Cdk4 and AKT. By depleting these kinases, apigenin suppressed both constitutive and inducible activation of STAT3, ERK, AKT and NF-κB. The treatment also downregulated the expression of the antiapoptotic proteins Mcl-1, Bcl-2, Bcl-xL, XIAP and Survivin, which ultimately induced apoptosis in MM cells. In addition, apigenin had a greater effects in depleting Hsp90 clients when used in combination with the Hsp90 inhibitor geldanamycin and the histone deacetylase inhibitor vorinostat. CONCLUSIONS: Our results suggest that the primary mechanisms by which apigenin kill MM cells is by targeting the trinity of CK2-Cdc37-Hsp90, and this observation reveals the therapeutic potential of apigenin in treating multiple myeloma.

Epstein-Barr virus-coded miR-BART13 promotes nasopharyngeal carcinoma cell growth and metastasis via targeting of the NKIRAS2/NF-κB pathway.

Based on analysis of Epstein-Barr virus (EBV) BART microRNA expression profiles, we previously reported that EBV-encoded miR-BART13 is upregulated in nasopharyngeal carcinoma (NPC) plasma specimens. However, the effects and molecular mechanisms of miR-BART13 in NPC remain largely unknown. We found that miR-BART13 was significantly upregulated in NPC tissue specimens. Ectopic expression of miR-BART13 promoted NPC cell proliferation, epithelial mesenchymal transition, and metastasis in vitro, and facilitated xenograft tumor growth and lung metastasis in vivo. Molecularly, NF-κB inhibitor interacting Ras-like 2 (NKIRAS2), a negative regulator of the NF-κB signaling, was identified to be a direct target of miR-BART13 in NPC cells, and NKIRAS2 mRNA and protein expression was inversely correlated with miR-BART13 in NPC tissues, respecitvely. Furthermore, the NF-κB signaling pathway was activated by miR-BART13. By rescued experiments, reconstitution of NKIRAS2 expression abrogated all the phenotypes upregulated by miR-BART13, and attenuated activity of NF-κB signaling pathway activated by miR-BART13 in NPC cells. Our findings indicated the newly identified miR-BART13/NKIRAS2/NF-κB signaling axis may provide further insights into better understanding of NPC initiation and development, and targeting of this pathway could be further studied as a therapeutic strategy for NPC patients.

Analysis on clinical characteristics and influencing factors of patients with locoregionally advanced nasopharyngeal carcinoma.

BACKGROUND: To explore the independent prognostic factors for the recurrence/metastasis of patients with locoregionally advanced nasopharyngeal carcinoma (LANPC). MATERIALS AND METHODS: A total of 604 patients initially diagnosed as LANPC by pathohistology in Fujian Provincial Cancer Hospital were selected to analyze the relationship between the clinical pathological patterns, therapeutic protocols and clinical stages with the recurrence/metastasis of LANPC. RESULTS: The 1-, 3- and 5-year locoregionally recurrent rates of LANPC patients were 2.0%, 9.5% and 12.9% respectively, with average recurrent period being 78 months. Univariate analysis results indicated that clinical stages had certain influence on the recurrent period of LANPC patients. However, COX regression models showed that ages, genders and clinical stages were not the independent prognostic factors influencing the recurrence. The 1-, 3- and 5-year metastatic rates of LANPC patients were 6.6%, 17.5% and 18.8% respectively, with average metastatic period of 73 months. Univariate analysis results demonstrated that ages, N stages, clinical stages, locations of lymph node, retropharyngeal lymph node and extracapsular invasion of lymph node had certain influence on the metastatic period of LANPC patients. Additionally, further COX regression analysis results suggested that T stages, reduction protocols and extracapsular invasion of lymph node were the independent prognostic factors influencing the metastasis of patients with LANPC, in which T stages and extracapsular invasion of lymph node were the pestilent factors while reduction protocols the protective factor. CONCLUSIONS: Induction chemotherapy is beneficial to LANPC patients with initial treatment, and the metastatic rate decreases greatly after the application of reduction chemotherapy.

[Differentially expressed genes in human giant-cell lung cancer lines with different metastatic potentials].

OBJECTIVE: To screen genes differentially expressed in two human giant-cell lung cancer lines of same origin but with different metastasis potentials. METHODS: Suppression subtractive hybridization (SSH) was done twice on two giant-cell lung cancer lines, PLA-801C and PLA-801D (hereafter abbreviated as C and D), of same origin but with low (C) and high (D) metastatic potentials. In the first round, SSH C was used as tester and D as driver, while in the second round, the tester and driver were interchanged. The sequences acquired from both rounds of SSH were spotted on glass slides respectively and screened by hybridizing with two-color fluorescence probes. Clones that had different expression levels on chips were also confirmed by RNA dot blot or Northern blot. RESULTS: There were 16 sequences with high expression in C as compared to those in D, and 79 sequences with high expression in D compared to those in C. After sequencing, most of them were found to be highly homologous to those encoding the following proteins: (1) cytokines and their receptors; (2) kinases and related proteins; (3) other proteins including enzymes, heat shock proteins, receptors, proteins of cell skeleton and mitochondria, products of oncogenes, etc; (4) some proteins deduced from gene sequences with yet unknown functions. CONCLUSION: The alterations in expression of some known genes, including HSP70, AXL receptor tyrosine kinase and 14-3-3zeta, might have impact on metastasis of giant-cell lung cancer. Whether some differentially expressed genes newly revealed are metastasis-related needs further study.

[The specific killing of human melanoma cells by replication selective adenovirus].

OBJECTIVE: To construct replication selective adenovirus AdhepE1 targeting human melanoma and observe its specific killing of human melanoma cells in vitro. METHODS: Adenovirus E1 region, the murine tyrosinase promoter and enhancer DNA sequences were acquired respectively by PCR cloning. The shuttle plasmid of replication-selective adenovirus targeting human melanoma was constructed by DNA recombination. Replication-selective adenovirus AdhepE1 was generated by homologous recombination. The human melanoma cell line SK-Mel-1 and hepatocellular carcinoma cell line HepG2 were attacked separately by lower dose of AdhepE1. Change of cell morphology was observed and the surviving cells were calculated. The expression of E1A was assayed by RT-PCR to verify the specific-replication of AdhepE1. RESULTS: Replication selective adenovirus AdhepE1 targeting human melanoma was acquired by PCR. Human melanoma cell line SK-Mel-1 was sensitive to oncolytic killing of AdhepE1 whereas HepG2 was little responsive. The results of RT-PCR suggested that AdhepE1 replicated specifically in human melanoma cells. CONCLUSION: AdhepE1 can selectively kill human melanoma cells.

[Construction and expression of the efficient recombinant plasmid pEE14.1-IFN-α expressing human IFN-α].

AIM: To construct the eukaryotic expression plasmid pEE14.1-IFN-α expressing human IFN-α gene, and to detect the expression of the plasmid in eukaryotic cells. METHODS: The human IFN-α gene amplified by PCR and was linked into pCI-GPI, then inserted into the eukaryotic expression vector pEE14.1. The recombinant plasmid was transfected into the 293T cells, the IFN-α expression was detected by ELISA and Western blotting. RESULTS: Enzyme digestion and sequence analysis showed that the bicistronic eukaryotic expression vector pEE14.1-IFN-α was constructed successfully. The expression of plasmid was detected by ELISA, and the production of IFN-α in supernatant of transfected cells was about 3.15 ng/mL. Also, Western blotting could reveal the characteristic band of IFN-α gene. CONCLUSION: The vector is constructed successfully, which provide a new selection for HBV immunotherapy.

Histone deacetylase inhibitor SAHA induces ERalpha degradation in breast cancer MCF-7 cells by CHIP-mediated ubiquitin pathway and inhibits survival signaling.

Estrogen receptor alpha (ERalpha) plays an important role in the development and progression of breast cancer, and recent studies showed that ERalpha expression is associated with resistance to hormonal therapy. Therefore, a number of studies have explored ways to deplete ERalpha from breast cancer cells as a new therapy especially for hormone-refractory breast cancer. We reported here that suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, effectively depletes ERalpha in breast cancer MCF-7 cells. However, the intrinsic mechanisms by which SAHA decreases ERalpha levels are not clear. Our present data demonstrated that both inhibition of ERalpha mRNA level and promotion of ERalpha degradation by the proteasome contribute to SAHA-induced ERalpha depletion, indicating that SAHA may exert its effects through transcriptional and posttranslational mechanisms. Furthermore, the decrease of ERalpha protein level in MCF-7 cells after SAHA treatment is mainly the result of its rapid degradation by the ubiquitin-proteasome pathway rather than transcriptional inhibition. In addition, we showed that inactivation of the heat shock protein-90 (Hsp90) is involved in SAHA-induced ERalpha degradation, and ubiquitin ligase CHIP (C-terminal Hsc70 interacting protein) enhances SAHA-induced ERalpha degradation. SAHA-induced ERalpha depletion is paralleled with reduction of transcriptional activity of ERalpha and SAHA is able to effectively inhibit cell proliferation and induce apoptosis of MCF-7 cells. Taken together, our results revealed a mechanism for SAHA-induced ERalpha degradation and indicated that SAHA is a suitable pharmacological agent for depletion of ERalpha and a potential choice for breast cancer expressing high ERalpha.

[Overexpression of CHIP in chronic myeloid leukemia K562 cells induces mitotic abnormality].

This study was aimed to investigate the possible influence of a novel E3 ubiquitin ligase CHIP (carboxyl terminus of Hsc70/Hsp70-interacting protein) on biological characteristics of cancer cells. Stable overexpression models in CML K562 cells were established via lipofectamine-mediated wild type CHIP and its TPR or U-box deletion mutants gene transfection. Followed G418 pressure selection, K562-CHIP stable transfected cell clones were obtained by limited dilution. The proliferation status and cell cycle were observed by MTT assay and FACS. The expression of related proteins and morphological changes were detected by Western blot and Wright-Giemsa staining. The results showed that overexpression of wild type CHIP did not inhibit cell proliferation, but slightly increased cell ratio of G(2)/M phase. CHIP gene had no effect on the stability of BCR-ABL kinase protein. HDAC inhibitor FK228-induced BCR-ABL degradation did not enhanced by CHIP. Notably the enlarged cells and abnormal mitotic cells remarkably increased in K562 WT-CHIP cells, indicating that CHIP may involve in the regulation of mitotic process. It is concluded that wild type CHIP induces mitotic abnormity in K562 cells.

[Histone deacetylase inhibitor SAHA induces inactivation of MAPK signaling and apoptosis in HL-60 cells].

The study was aimed to investigate the molecular mechanisms of histone deacetylase inhibitor SAHA-induced apoptosis of acute myeloid leukemia cell line HL-60. The effect of SAHA on HL-60 cell proliferation was detected by MTT assay and the cell morphological changes were observed with Wright-Giemsa and Hoechst33342 staining. The cell cycle distribution was determined by flow cytometry and the expression of cell signaling proteins were detected by Western-blot analysis. The results showed that SAHA inhibited the proliferation of HL-60 cells in dose- and time-dependent manners, after 2 micromol/L SAHA exposure for 12 - 48 hours, the cell cycle was arrested at G(0)/G(1) phase and apoptotic cell death was confirmed by either defined apoptotic bodies stained by Hoechst33342, Western blot showed cleaved-PARP, which represents the activation of caspase 3. The Western blot analysis indicated the activation of two important survival signal pathways after SAHA treatment, the phosphorylation of Raf and its downstream ERK kinases were remarkable downregulated, whereas the phosphorylation of AKT and its downstream molecular mTOR were not changed. It is concluded that SAHA-induced apoptosis of HL-60 cells is mediated by inactivation of p44/42 MAPK signaling pathway.

FK228 inhibits Hsp90 chaperone function in K562 cells via hyperacetylation of Hsp70.

Some pan-histone-deacetylase (HDAC) inhibitors have recently been reported to exert their anti-leukemia effect by inhibiting the activity of class IIB HDAC6, which is the deacetylase of Hsp90 and alpha-tubulin, thereby leading to hyperacetylation of Hsp90, disruption of its chaperone function and apoptosis. In this study, we compared the effect of a class I HDAC inhibitor FK228 with the pan-HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) on the Hsp90 chaperone function of K562 cells. We demonstrated that, although having a weaker inhibitory effect on HDAC6, FK228 mediated a similar disruption of Hsp90 chaperone function compared to SAHA. Unlike SAHA, FK228 did not mediate hyperacetylation of Hsp90, instead the acetylation of Hsp70 was increased and Bcr-Abl was increasingly associated with Hsp70 rather than Hsp90, forming an unstable complex that promotes Bcr-Abl degradation. These results indicated that FK228 may disrupt the function of Hsp90 indirectly through acetylation of Hsp70 and inhibition of its function.

[Construction and study of replication-defective adenovirus targeting hepatocarcinoma].

BACKGROUND & OBJECTIVE: Antioncogene p16 is one of the most important genes used in tumor gene therapy. Apoptosis induced by adenovirus mediated overexpression of p16 in cancer cells has been confirmed in various p16 gene inactive cancers. Studies have indicated that p16 gene is frequently inactive in human primary hepatocarcinoma. Therefore this study was to investigate the effect of exogenous p16 gene driven by alpha fetoprotein (AFP) core promoter on human hepatocellular carcinoma cells and further explore the potentials of p16 in hepatocellular carcinoma gene therapy. METHODS: The recombinant replication-defective adenovirus Ad-AFP-p16 containing p16 gene downstream the AFP core promoter-AF0.3 was constructed and infected hepatocellular carcinoma cells. The expression of p16 was detected by Western blot. The effects of exogenous p16 gene on cell growth and apoptosis were measured by MTT, flow cytometry and DNA ladder in vitro. Subcutaneous injection of mouse hepatocarcinoma cell line H22 infected with Ad-AFP-p16 was applied to observe the effect of Ad-AFP-p16 on tumorigenesis in vivo. RESULTS: Over-expression of exogenous p16 gene was confirmed in hepatocarcinoma cells infected with Ad-AFP-p16. Cell growth was inhibited by (94.42+/-11.70)% and (94.99+/-6.74)% in Be1-7402 and HepG2 cells on the 6th day after virus infection; 39.57% and 39.75% apoptotic cells were also induced respectively in these two cell lines on the 2nd day. Moreover, the infection of Ad-AFP-p16 significantly inhibited the tumorigenesis of mouse hepatocarcinoma cell line H22 in vivo. The tumor volumes of control, Ad-GFP, Ad-AFP-p16 and Ad-CMV-p16 groups were (1.54+/-0.65)cm(3), (1.71+/-1.01)cm(3), (0.25+/-0.39)cm(3) and (0.25+/-0.45)cm(3), respectively. CONCLUSION: The expression of p16 gene driven by AFP promoter can induce apoptosis in hepatocarcinoma cells.