[Effects of CSN4 knockdown on proliferation and apoptosis of breast cancer MDA-MB-231 cells].

Breast cancer is one of the most common malignant tumors endangering women. It has been found that the subunits of the COP9 complex are closely related to the occurrence and development of malignant tumors, and the CSN4 subunit plays an important role in regulating the whole complex. In the breast cancer cell line MDA-MB-231, we successfully established a lentivirus-mediated CSN4-knockdown cell line. CCK8 cell proliferation assays and colony formation experiments confirmed that CSN4 knockdown significantly decreased the cellular proliferation rate. Cell cycle analysis showed that CSN4 knockdown increased sub-G1 population and induced apoptosis. In addition, Western blotting assays confirmed that CSN4 regulates the expression of CDK6 and Caspase3, suggesting that CSN4 modulates the proliferation and apoptosis of breast cancer cells by regulating the expression of CDK6 and Caspase3 genes and thereby tumorigenesis. This study has deepened our understanding of the molecular mechanism of apoptosis and cell growth in breast cancers, and further revealed the role and mechanism of CSN4 in cancer biology.

[Preparation and identification of immune serum against recombinant fusion protein of rhoptry 2 and major surface protein 1 from Toxoplasma gondii].

OBJECTIVE: To prepare and identify immune serum against the recombinant fusion protein of rhoptry 2 (ROP2) and major surface protein 1(P30) from Toxoplasma gondii. METHODS: The constructed recombinant plasmid of pET28b/ROP2-P30 was transformed to a bacterium BL21-Codon Plus (DE3)-RIL strain and was expressed under IPTG induction. Cells were lysed by multiple rounds of sonication to obtain supernatant and inclusion body respectively. The inclusion body was washed with 2 mol/L and 4 mol/L urea to remove the nonspecific protein. The washed products dissolved in 8 mol/L urea were received by SDS-PAGE. Two rabbits were immunized with the fusion protein rROP2-P30 and sera from the rabbits were collected. Immune diffusion test, indirect ELISA and Western-blot were used to detect antibody titer and specificity of the immune serum against rROP2-P30. RESULTS: Immune diffusion test demonstrated that specific immune serum were obtained. Indirect ELISA confirmed that the antibody titer in the serum reached 1:12 800 and the rROP2-P30 was recognized by specific IgG in this serum by Western-blot analysis. CONCLUSION: Specific immune serum against the recombinant fusion protein rROP2-P30 has been prepared.

Cost-effective method of siRNA preparation and its application to inhibit hepatitis B virus replication in HepG2 cells.

AIM: To find a cost-effective method of preparation of short interfering RNAs based on cloning, fermentation, digestion and purification (CFDP) and test its feasibility to inhibit hepatitis B virus replication in cell culture. METHODS: We constructed an expression vector containing T7 and tac promoter in a head-to-head orientation. cDNA fragment of interest was cloned into this vector between the opposing promoters. dsRNAs were expressed with this vector in Escherichia coli, and purified by affinity chromatography using CF 11 column. They were digested by RNase III in a buffer containing manganese ions, then separated on 15% non-denaturing PAGE, and the siRNAs about 25 bp in length were recovered. siRNAs prepared with CFDP were co-transfected with target gene expression plasmid into human cell lines with lipofectamine 2,000 to test their inhibition efficiency. RESULTS: siRNAs corresponding to part of the hepatitis B virus polymerase gene (siHBVP) prepared by CFDP specifically and dramatically suppressed the virus protein expression. The HBsAg expression level was reduced to 10% that of the control by co-transfection of 60 nmol/L siHBVP in SMMC7721 cells. Dose-dependent effect on suppression of HBsAg and HBeAg expression was observed in HepG2 cells. The highest inhibition rate was kept at 70% during the six days after transfection of 7.5 nmol/L siHBVP. CONCLUSION: We show CFDP is a very promising method to prepare therapeutic agents in anti-virus applications.

[Cloning and expression of the fused gene of rhoptry protein ROP2 and major surface protein P30 from Toxoplasma gondii].

OBJECTIVE: To clone and express the fused gene fragment coding rhoptry protein ROP2 and major surface protein P30 from Toxoplasma gondii as a preparation for the construction of the complex ROP2-P30 antigen by gene engineering. METHODS: The gene fragment encoding P30 was amplified by PCR from T. gondii RH strain and subcloned into the recombinant plasmid pUC119/ROP2 already constructed. The recombinant plasmid pUC119/ROP2-P30 was digested by Sac I/HindIII and inserted into the same site of expression vector pET28b. The recombinant plasmid of pET28b/ROP2-P30 was transformed to E. coli and expressed under the induction of IPTG. RESULTS: The gene fragment 700 bp encoding P30 was obtained from the total DNA of T. gondii by PCR. The recombinant plasmid pET28b/ROP2-P30 was successfully constructed, which was highly expressed in E. coli, a fusion protein with molecular weight of 69000. CONCLUSION: The fusion gene encoding the rhoptry protein ROP2 and the major surface protein P30 of T. gondii has been successfully cloned and expressed to be an expected recombinant fusion protein ROP2-P30 with molecular weight 69000.