[Adenovirus-mediated double suicide gene selectively kills breast cancer MCF-7 cells in vitro].
OBJECTIVE
To evaluate the effect of adenovirus-mediated double suicide gene (CD/TK) for selective killing of breast cancer cells.


METHODS
Vascular endothelial growth factor (VEGF)-expressing MCF-7 cells and normal human mammary epithelial cells that did not express VEGF were infected with the adenovirus containing VEGFP-CD/TK-GFP genes. CD/TK gene expression in the infected cells was detected by RT-PCR. After treatment of the infected cells with GCV and/or 5-FC, the cell growth status was evaluated using MTT assay, and the cell cycle changes were detected with flow cytometry. In nude mice bearing human breast cancer, the recombinant adenovirus vector was injected directly into the tumor followed by intraperitoneal injection of the prodrugs GCV and/or 5-FC, and the subsequent tumor growth was observed.


RESULTS
The recombinant adenovirus achieved similar infection rates in MCF-7 and human mammary epithelial cells, and the rates increased gradually with the multiplicity of infection (MOI) of the virus. RT-PCR demonstrated the presence of CD/TK gene product in infected MCF-7 cells, but not in the infected mammary epithelial cells. The infected MCF-7 cells, but not the mammary epithelial cells, were highly sensitive to the pro-drugs. The CD/TK fusion gene system showed significantly greater efficiency than either of the single suicide gene in killing the target cells (P<0.01). At the MOI of 100, treatment of the infected cells with the pro-drugs resulted in increased cell percentage in G(0)-G(1) phase and decreased percentage in S phase. In nude mice bearing MCF-7 cell-derived subcutaneous tumor, treatment with the double suicide gene system significantly inhibited the tumor growth, showing much stronger effect than either of the single suicide gene (P<0.01).


CONCLUSIONS
The adenovirus-mediated CD/TK double suicide gene driven by VEGF promoter combined with GCV and 5-FC treatment can be an effective therapy against experimental breast cancer, and produces much greater efficacy than the single suicide gene CD/TK combined with GCV or 5-FC.
Kong
Heng
H
Department of General Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.
Huang
Zong-Hai
ZH
Li
Qiang
Q
Yang
Liu-Cheng
LC
Yu
Jin-Long
JL
Li
Zhou
Z
D000256:Adenoviridae / Q000235:genetics*; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D043525:Cytosine Deaminase / Q000235:genetics / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D005437:Flucytosine / Q000494:pharmacology; D015774:Ganciclovir / Q000494:pharmacology*; D041722:Genes, Transgenic, Suicide / Q000235:genetics*; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013937:Thymidine Kinase / Q000235:genetics / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
D011993:Recombinant Fusion Proteins; D042461:Vascular Endothelial Growth Factor A; D049452:Green Fluorescent Proteins; D005437:Flucytosine; D013937:Thymidine Kinase; D043525:Cytosine Deaminase; D015774:Ganciclovir