Upregulation of drug sensitivity of multidrug resistant SGC7901/VCR human gastric cancer cells by bax gene transduction

To investigate the role of bax in a vincristine (VCR) induced multidrug resistant (MDR) human gastric cancer cell line, SGC7901/VCR, in which the Bax protein expression level was significantly lower compared with that in parent cells Methods A bax eukaryotic expression vector was constructed and transfected into SGC7901/VCR cells by lipofectamine, and resistant clones were selected by G418 Western blotting detected Bax expression in transfectants Tetrazolium blue (MTT) assay evaluated the differences in drug sensitivity and cell cycle changes of transfectants were analyzed using flowcytometry (FCM) Results The bax eukaryotic expression vector was constructed and transfected into SGC7901/VCR cells Through G418 selection, resistant clones were obtained Western blotting demonstrated that the expression of Bax protein was markedly increased in bax transduced cells These cells were more sensitive to adriamycin (ADR) and VCR than mock vector transducted cells Moreover, bax transfection enhanced ADR induced apoptosis and VCR induced G 2/M phase arrest of SGC7901/VCR cells Conclusion Bax was involved in the MDR of SGC7901/VCR cells

ANTITUMOR EFFECTS OF HUMAN IL-15 GENE MODIFIED LUNG CANCER CELL LINE

Human IL15 cDNA fragment, which contains all codons encoding the human IL15 mature protein and signal peptide was transducted into the human lung squmouse cancer cells(PG cells) and murine lung adenocarcinoma cells(LA795 cell lines). Two IL15 highly expressed cell clones PG1 and LA795A were used to inoculate the nude mice and the T739 syngeneic mice respectively. PG1 cell express higher level of class ⅠMHC molecule on their surface than PG cells. It was shown that the modified LA795A tumor cells grew slowly in T739 mice and induced high levels of CTL/NK/LAK activity in vivo as well, compared with the case of inoculation with LA795 or LA795neo. No significant difference in the tumor growth was observed in groups of the nude mice inoculated by PG1, PG and PGneo cells respectively, except the gene modified cells could not show the lung metastasis of tumors. The supernatants derived from the LA795A cell culture could promote CTL/NK/LAK activity from the whole splenocytes and the CD4/CD8deleted splenic cells in vitro. The results indicated that the IL15 gene transfected tumor cells play important roles in the process of antitumor or antitumor metastasis.

Caspase 3 siRNA decreases apoptosis in cultured neuronal cells

BACKGROUND： Lentiviral vectors, a type of retroviral vector, are able to infect cells at all phases of cell cycle. They are able to express exogenous target genes in vivo over long periods of time with limited immunological reaction. OBJECTIVE： To inhibit neuronal apoptosis by blocking the apoptotic cascade reaction, gene silencing of Caspase 3, and transfection of Caspase 3 short hairpin ribonucleic acid （shRNA） into Neuro 2a cells using a lentiviral vector.DESIGN： TiME-AND SETTING： An observational, genetic engineering cellular biology experiment was performed in Guangzhou Red Cross Hospital and Guangzhou Institute of Traumatic Surgery between March 2007 and June 2008. MATERIALS： PLL3.7, PCMV-VSV-G, and PH＇8.9∧PR plasmids were provided by the CBR Institute for Biomedical Research, Harvard Medical School, USA. Staurosporine was purchased from Sigma, USA.METHODS： Caspase 3 siRNA was synthesized and cloned into the PLL3.7 plasmid. The Caspase 3 shRNA-PLL3.7 Ientivirus was generated in 293T cells using a calcium phosphate transfection kit. After the lentivirus was transfected into Neuro 2a cells, apoptosis was induced in both the transfected and untransfected cells by staurosporine. Cell apoptosis was assessed by flow cvtometrv.MAIN OUTCOME MEASURES： Caspase 3 mRNA expression was measured by RT-PCR and Caspase protein expression was assessed by Western blot. Cellular apoptosis was determined by flow cytometry using Annevin V-PE/Taad-Cy7. RESULTS： The transfection rate of caspase 3 shRNA was 〉 98% using the lentiviral vector, RT-PCR and Western blot results demonstrated that significantly reduced Caspase 3 mRNA and protein expression in the transfected Neuro 2a. The control group exhibited 38.7% Annexin V/7aad-positive cells, which suggested apoptotic anaphase, while only 5.0% cells in the Caspase 3 gene silencing group entered apoptotic anaphase. CONCKUSION： Caspase 3 shRNA inhibited Caspase 3 expression in Neuro 2a ceils and decreased drug-induced apoptosis of Neuro 2a cells.

Phage-mediated horizontal gene transfer and its implications for the human gut microbiome

Horizontal gene transfer(HGT)in the microbiome has profound consequences for human health and disease.The spread of antibiotic resistance genes,virulence,and pathogenicity determinants predominantly occurs by way of HGT.Evidence exists of extensive horizontal transfer in the human gut microbiome.Phage transduction is a type of HGT event in which a bacteriophage transfers non-viral DNA from one bacterial host cell to another.The abundance of tailed bacteriophages in the human gut suggests that transduction could act as a significant mode of HGT in the gut microbiome.Here we review in detail the known mechanisms of phage-mediated HGT,namely specialized and generalized transduction,lateral transduction,gene-transfer agents,and molecular piracy,as well as methods used to detect phage-mediated HGT,and discuss its potential implications for the human gut microbiome.