Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.4.1 (cytosine deaminase)
 747 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 2.4-kb truncated L-plastin promoter was inserted either 5' to the LacZ gene (Ad-Lp-LacZ) or 5' to the cytosine deaminase (CD) gene (Ad-Lp-CD) in a replication-incompetent adenoviral vector backbone. Infectivity and cytotoxicity experiments with the LacZ and CD vectors suggested that the L-plastin promoter-driven transcriptional units were expressed at much higher levels in explants of ovarian cancer cells from patients and in established ovarian or bladder cancer cell lines than they were in normal peritoneal mesothelial cells from surgical specimens, in organ cultures of normal ovarian cells, or in the established CCD minimal deviation fibroblast cell line. Control experiments showed that this difference was not attributable to the lack of infectivity of the normal peritoneal cells, the normal ovarian cells, or the minimal deviation CCD fibroblast cell line, because these cells showed expression of the LacZ reporter gene when exposed to the replication-incompetent adenoviral vector carrying the cytomegalovirus (CMV)-driven LacZ gene (Ad-CMV-LacZ). The Ovcar-5 and Skov-3 ovarian cancer cell lines exposed to the Ad-Lp-CD adenoviral vector were much more sensitive to the prodrug 5-fluorocytosine (5FC), which is converted from the 5FC prodrug into the toxic chemical 5-fluorouracil, than was the CCD minimal deviation fibroblast cell line after exposure to the same vector. A mouse xenograft model was used to show that the Ad-Lp-CD vector/5FC system could prevent engraftment of ovarian cancer cells in nude mice. Finally, injection of the Ad-Lp-CD vector into s.c. tumor nodules generated a greater reduction of the size of the tumor nodules than did injection of the Ad-CMV-LacZ vectors into tumor nodules. The Ad-Lp-CD vectors were as suppressive to tumor growth as the Ad-CMV-CD vectors. These results suggest that an adenoviral vector carrying the CD gene controlled by the L-plastin promoter (Ad-Lp-CD) may be of potential value for the i.p. therapy of ovarian cancer.
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PMID:The use of the L-plastin promoter for adenoviral-mediated, tumor-specific gene expression in ovarian and bladder cancer cell lines. 1138 68

Prodrug activating transcription unit gene therapy is one of several promising approaches to cancer gene therapy. Combining that approach with conditionally replication-competent viral vectors that are truly tumor specific has been an important objective of recent work. In this study, we report the construction of a new conditionally replication-competent bicistronic adenoviral vector in which the cytosine deaminase (CD) gene and the E1a gene are driven by the L-plastin tumor-specific promoter (AdLpCDIRESE1a). A similar vector driven by the CMV promoter has also been constructed (AdCMVCDIRESE1a) as a control. We have carried out in vitro cytotoxicity in carcinomas of the breast, ovary and colon, and in vivo efficacy studies with these vectors in an animal model of colon cancer. While the addition of the AdLpCDIRESE1a vector to established cancer cell lines showed significant cytotoxicity in tumor cells derived from carcinomas of the breast (MCF-7), colon (HTB-38) and ovary (Ovcar 5), no significant toxicity was seen in explant cultures of normal human mammary epithelial cells (HMEC) exposed to this vector. The addition of 5-fluorocytosine (5FC) significantly increased the cytotoxicity in an additive fashion of both the AdLpCDIRESE1a and AdCMVCDIRESE1a vectors as well as that of the AdLpCD replication incompetent vector to established tumor cell lines. However, no significant cytotoxicity was observed with the addition of 5FC to explant cultures of normal human mammary epithelial cells that had been exposed to the L-plastin-driven vectors. Studies with mixtures of infected and uninfected tumor cell lines showed that the established cancer cell lines infected with the AdLpCDIRESE1a vector generated significant toxicity to surrounding uninfected cells (the "bystander effect") even at a ratio of 0.25 of infected cells to infected + uninfected cells in the presence of 5FC. The injection of the AdLpCDIRESE1a vector into subcutaneous deposits of human tumor nodules in the nude mice was potentiated by administering 5-FC by intraperitoneal injection. This treatment resulted in a decreased tumor size and a decreased tumor cell growth rate. The mice treated with a combination of the AdLpCDIRESE1a vector intratumoral injection and intraperitoneal 5FC injections lived much longer than the other experimental groups exposed to the viral vector alone or to the combination of the intratumoral AdLpCD replication incompetent vector injections plus intraperitoneal 5-FC injections. These encouraging results with our newly constructed AdLpCDIRESE1a vector suggest a need for further study of its utility in a preclinical model of intracavitary therapy of pleural or peritoneal carcinomatosis.
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PMID:Cytotoxic effect of replication-competent adenoviral vectors carrying L-plastin promoter regulated E1A and cytosine deaminase genes in cancers of the breast, ovary and colon. 1271 8

The expression of therapeutic transgenes in recombinant adenoviral vectors is a major cause of toxicity in dividing cancer cells as well as non dividing normal cells. To solve the problem of toxicity to normal cells, we have reported on a recombinant adenoviral vector system (AdLP-) in which the expression of the transgene is directed by the tumor-specific L-plastin promoter (LP) (Chung et al., 1999). The object of this study was to generate a recombinant adenoviral vector system which would generate tumor cell specific expression of cytosine deaminase (CD) gene. We report the construction of a replication-incompetent adenoviral vector in which CD is driven by the L-plastin promoter (AdLPCD). Infection of 293 cells by AdLPCD generated the functional CD protein as measured by HPLC analysis for the conversion of 5-Fluorocytosine (5-FC) to 5-Fluorouracil (5-FU). HPLC analysis in conjunction with counting radioactivity for [6-3H]-5FC and [6-3H]-5FU demonstrated vector dose-dependent conversion of 5-FC to 5-FU in AdLPCD infected ovarian cancer cells. The results from present and previous studies (Peng et al., 2001; Akbulut et al., 2003) suggest that the use of the AdLPCD/5-FC system may be of value in the treatment of cancer including microscopic ovarian cancer in the peritoneal cavity.
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PMID:Recombinant adenoviral vector containing tumor-specific L-plastin promoter fused to cytosine deaminase gene as a transcription unit: generation and functional test. 1528 66

We constructed a conditionally replication-competent adenoviral vector Ad.Lp-CD-IRES-E1A(control) in which the expression of both the prodrug-activating cytosine deaminase gene and the viral replication E1A gene were driven by the L-plastin tumor-specific promoter. In order to overcome the low infectivity of the adenoviral vectors for breast cancer cells, and to increase the safety and efficacy for cancer gene therapy, this vector was further modified on a transductional level by simultaneously ablating the native tropism of the vector to the primary CAR receptor and inserting a RGD-4C peptide into the HI loop of the fiber, which allows the vector to use the alphavbeta3 and alphavbeta5 receptors as alternative receptors. The resulting vector was named Ad.Lp-CD-IRES-E1A(MRGD). The transduction efficiency of the vector for breast cancer cell lines which have low expression level of CAR was increased both in vitro and in vivo. The Ad.Lp-CD-IRES-E1A(MRGD) vector produces a higher vector particle yield and a greater cytotoxic effect in tumor cells which have a low expression level of CAR, than did the Ad.Lp-CD-IRES-E1A(control) vector. Intratumoral injection of the Ad.Lp-CD-IRES-E1A(MRGD) vector following the intraperitoneal injection of 5FC into xenotransplanted human breast cancer cell lines which have low expression level of CAR led to greater degree of tumor regression in vivo than did the intratumoral injection of control adenoviral vectors not so modified.
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PMID:Engineering conditionally replication-competent adenoviral vectors carrying the cytosine deaminase gene increases the infectivity and therapeutic effect for breast cancer gene therapy. 1617 27

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.
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PMID:Cytotoxic effect of a replication-incompetent adenoviral vector with cytosine deaminase gene driven by L-plastin promoter in hepatocellular carcinoma cells. 1767 57