Research advances of Rb94 gene in malignant tumors / 国际肿瘤学杂志

Retinoblastoma 94(RB94)gene,a new tumor suppressor gene,is found in the past several years.It has been found that Rb94 gene has a more powerful antitumor effection compared with Rb110gene.After transfection,Rb94 gene could adjust telomerase activation,induce apoptosis and regulate cell cycle.It also has a synergistic action associated with radiotherapy or chemotherapy.

Radiosensitising effect of retinoblastoma gene (Rb94) on human lung adenocarcinoma cell line A549 / 中华放射肿瘤学杂志

Objective To construct an eukaryotic expression vector of retinoblastoma gene (pIRES-Rb94), and investigate the radiosensitising effect of Rb94 on lung adenocarcinoma cell line A549 and the mechanism. Methods Recombinant expression plasmid pIRES-Rb94 was constructed and then transfected into A549 cells using lipofectamine 2000. Steadily transfected cells were obtained using G418 se-lecting system. Cell counting method was used to produce the growth curve and the population doubling time was then calculated. The radiosensitivity of A549 cells was assessed by clonogenic assay. The expression of bTERT and Bcl-2 mRNA was detected by real-time RT-PCR. Cell cycle distribution was measured by flow cytometry. Results Steadily transfected cell line pIRES-Rb94-A549 was aquired. Compared with A549 cells, the population doubling time of pIRES-Rb94-A549 cells was increased from 31.5 h to 39.5 h (t=5.15, P<0.01). The expression of hTERT and Bcl-2 mRNA was both down-regulated (0.02:1.00, t= 18.99,P<0.01,0.01:1.00,t=13.73,P<0.01). The number of cells was increased in G2/M phases (35.91%:4.53%, t =36.78,P=0.00), whereas decreased in G0/G1 and S phases (47.02%:74.07%, t =11.71,P=0.00;17.07%:22.32%, t =2.30,P<0.05). The sensitizing enhancement ratio was 1.30. Conclusions Rb94 has marked radiosensitizing effect on A549 cells by G2/M phase blockage and down-regulation of hTERT and Bcl-2 mRNA expression. Rb94 may also inhibit the ability of cell proliferation by regulating cell cycle distribution.

A study on the deletion and mutation of Rb gene in lung cancer / 国际检验医学杂志

Objective To investigate the deletion and mutation of Rb gene in human lung cancer.Methods Polymerace chain reaction (PCR ) and restriction enzyme analytic techniques were used to detect the exon 14-16 and 22-23 regions of Rb gene in 20 human lung cancer DNA samples and 3 normal human lung tissue DNA samples.Results Two deletions existed in the exon 14-16 regions of two lung cancer DNA samples.Conclusion Deletion of Rb gene is in existance in human lung cancer, especially in small cell lung cancer. This may be useful for studying the cause of lung cancer.

The study on mechanism of enhancing bystander effect of HSV-TK/GCV system by Rb gene / 中华骨科杂志

Objective To explore an alternative strategy of ganciclovir-mediated cytotoxicity and study the mechanism of enhancing bystander effect of HSV-TK/GCV system by combination gene transfer of Rb gene and HSV-TK gene.Methods Recombinant eukaryotic expression plasmid pcDNA3.1-Rb harbour ing1.65kb of Rb gene was constructed.The pcDNA3.1-Rb and the plasmids tgCMV/HyTK car-ry ing HSV-TK gene were transfected respectively or co-transfected into the osteosarcoma cell line OS732by lipofection using DOTAP reagent.The mRNA expression of Rb gene and HSV-TK gene were detected by RT-PCR and Northern blot.Cell counting,cell cycle analysis and soft agar colony formation test were adopted to observe cell growth features.The expression of gap junction Connexin43gene was performed by RT -PCR and Western blot.The direct confirmation of gap junction intercellular commu ni cation was demonstrated by Lucifer yellow dye transfer.Cell sensitivity to GCV and″bystander effect″of HSV-TK/GCV system were measured by MTT assay.Results The eukaryotic expression plasmid pcD NA3.1-Rb was constructed successfully.The transfected cell lines OS732TK,OS732Rb and OS732RbTK were har-vested.mRNA expression of HSV-TK gene was demonstrated in OS732TK and OS732RbTK cells.Both exogenous and endogenous Rb gene expression could be detected in OS732Rb and OS732RbTK cells si-multa neously.Compared with parental cell OS732,OS732Rb and OS732RbTK cells changed their mor -phology and decreased the growth rate;the ability of soft agar colony formation reduced and the cell cycles were arrested at G 0 G 1 checkpoint.The Connexin43expression and gap junction in tercellular communica-tion en hanced in OS732Rb cell.GCV was of toxicity to only TK -positive cells,OS732TK and OS732RbTK,in a concentration dependent manner,the mixed coculture experiments of OS732and OS732Rb with the TK-negative cell,both showed sensitive to GCV,but the survival rate of OS732Rb cell was significantly lower than OS732cell under the same condition.Conclusion Coordinate ex pression of Rb andHSV-TK gene conferred a more po tent bystander effect by enhancing gap junction intercellular communica-tion and in hibiting prolifera tion.

EXPRESSION OF Rb AND p53 GENE IN GASTRIC CARCINOMAS IN RELATION TO PROGNOSIS / 中国癌症杂志

PURPOSE Expression of Rb and p53 gene in gastric carcinomas and its relationship to prognosis as well as clinico pathology were investigated.METHODS Expression of Rb and p53 products and p53 gene mutation in gastric carcinomas were analysed by means of immunohistochemistry and in situ hybridazation.RESULTS p53 gene mutation was found in 6/20(30%).Over expression of Rb and p53 products was found in 62/85(72.94%) and 42/85(49.41%).Both the positive grades showed significant inverse correlation with patient survival( P