Radiation Combined Cd Suicide Gene On Colorectal Cancer Cell Killing Effects Of Research

Radiation Combined with CD SuicideGene Therapy Enhances Killing of ColorectalCarcinoma Cells in VitroAbstractObjective Colorectal cancer is a major public health problem.Conventional therapies for advanced colorectal cancer are uneffective.There is a pressing need for effective treatment of colorectal cancer and colorectal liver metastases.Gene therapy has made greatly progress for the treatment of cancer in the last ten years.Suicide gene therapy for colorecta[ cancer was initiated with high levels of optimism and enthusaiasm.Rccently,this perception has had to be tempered by the realization that efficiency of gene delivery and instability of gene expression remain the most significant barriers to its success.It is known that radiation can improve gene transfer,we show here the antitumoral effect of radiation combined with suicide gene therapy on colorectal carcinoma cells.Methods We constructed plasmid DNA(pCDA) encoding cytosine deaminase(CD) suicide gene which used for gene therapy. LoVo colon adenocarcinoma cells and 8348 rectal adenocarcinoma cells were transfected in vitro with CD gene using liposome-mediated gene transfer systems.G4 18 was used to select CD positive neoplasm cells and CD gene transfer efficiency was tested by cloning efficiency. GFP could be seen under fluorescent microscope .GFP gene was used for reporting gene to learn gene transfer efficiency and gene expressing time under the influence of radiation. Antitumoral effect of radiation combined with CDI5-FC on colorectal carcinoma cells was tested by MTT.Results The transfer efficiency for Iiposome-mediated gene transfer systems was 5.4%~6.8%.There was no difference between supercoiled plasmid andlinearized plasmid(P>0. 05) .4Gy radiation could improve supercoiled plasmid DNA transfer efficiency for about 2~棐4 times and 6~ 10 times for linearized plasmid DNA.The mean durations of GFP gene expression treated with 4Gy radiation were 14 days for supercoiled plasmid and 21 days for linearized plasmid,while in control group,the time was 12 days.Middle-dose radiation combined with CDI5-FC could kill 99 percents of colorectal carcinoma cells,while in the control group,5-FC only killed 13 percents of colorectal carcinoma cells which were transduced with CD gene.Conclusions 5-FC could kill CD positive colorectal cancer cells and CD/5-FC has bystander effect.Radiation can improve plasmid transfection efficiency in colorectal cancer cells,especially for linearized plasmid. Radiation enhances antitumoral effect of suicide gene therapy on colorectal cancer.Radiation combined with suicide gene therapy may be used as a promising method for treating colorectal neoplasm.