Cytotoxic effect of a replication-incompetent adenoviral vector with cytosine deaminase gene driven by L-plastin promoter in hepatocellular carcinoma cells.
Great expectations are set on gene therapy for the treatment of malignant hepatocellular carcinomas (HCC) in East Asia. Recombinant adenoviral vectors (AV) have been developed in which the L-plastin promoter (LP) regulates the expression of transgenes, in a tumor cell specific manner, resulting in an increase in the therapeutic index. The development of the AdLPCD vector, a replication-incompetent AV, containing a transcription unit of LP and E. coli cytosine deaminase (CD), was reported in our previous work. In the present study, the AdLPCD vector combined with 5-fluorocytosine (5-FC) administration was tested to see if it might have significant utility in the chemosensitization of L-plastin positive HCC. Four HCC cell lines (HepG2, Chang Liver, Huh-7 and SK-Hep-1 cells) were investigated for the expression of LacZ after infecting the cells with the AdLPLacZ vector containing a 2.4 kb fragment of LP and the LacZ gene. Relatively high levels of LP activity were detected in HepG2, followed by Chang Liver cells; whereas, no promoter activity was found in Huh-7 and SK-Hep-1 cells, as determined by AdLPLacZ infection followed by the beta-galactosidase assay. In addition, the results of RT-PCR assays for the detection of endogenous L-plastin mRNA in these cells lines correlated well with those of the beta-galactosidase activity after infection with AdLPLacZ. Based on these data, the cytotoxic effect of AdLPCD/5-FC was evaluated in HepG2 cells. These results indicate that the CD gene delivered by AV could sensitize HepG2 cells to the prodrug, 5-FC. However, the observed effects were insufficient to cause the death of most of cells. This suggests that the screening of patients for an AdLP/5-FC strategy based on AdLPLacZ data might not always guarantee a good therapeutic outcome.
College of Pharmacy, Duksung Women's University, Dobong-gu, Seoul, Korea.
Kihwa
K
Jung
Sunja
S
Kim
Kyumhyang
K
Lee
Changmin
C
Kim
Injae
I
Chung
D000256:Adenoviridae / Q000235:genetics*; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D045744:Cell Line, Tumor; D003587:Cytomegalovirus / Q000235:genetics; D043525:Cytosine Deaminase / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D005822:Genetic Vectors / Q000235:genetics / Q000627:therapeutic use*; D006801:Humans; D007763:Lac Operon; D008113:Liver Neoplasms / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D010750:Phosphoproteins / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014779:Virus Replication / Q000235:genetics; D001616:beta-Galactosidase / Q000378:metabolism
D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D010750:Phosphoproteins; C026742:plastin; D001616:beta-Galactosidase; D043525:Cytosine Deaminase