Bifunctional chimeric SuperCD suicide gene -YCD: YUPRT fusion is highly effective in a rat hepatoma model.
OBJECTIVE
To investigate the effects of catalytically superior gene-directed enzyme prodrug therapy systems on a rat hepatoma model.


METHODS
To increase hepatoma cell chemosensitivity for the prodrug 5-fluorocytosine (5-FC), we generated a chimeric bifunctional SuperCD suicide gene, a fusion of the yeast cytosine deaminase (YCD) and the yeast uracil phosphoribosyltransferase (YUPRT) gene.


RESULTS
In vitro stably transduced Morris rat hepatoma cells (MH) expressing the bifunctional SuperCD suicide gene (MH SuperCD) showed a clearly marked enhancement in cell killing when incubated with 5-FC as compared with MH cells stably expressing YCD solely (MH YCD) or the cytosine deaminase gene of bacterial origin (MH BCD), respectively. In vivo, MH SuperCD tumors implanted both subcutaneously as well as orthotopically into the livers of syngeneic ACI rats demonstrated significant tumor regressions (P<0.01) under both high dose as well as low dose systemic 5-FC application, whereas MH tumors without transgene expression (MH naive) showed rapid progression. For the first time, an order of in vivo suicide gene effectiveness (SuperCD>> YCD>>BCD>>>negative control) was defined as a result of a direct in vivo comparison of all three suicide genes.


CONCLUSIONS
Bifunctional SuperCD suicide gene expression is highly effective in a rat hepatoma model, thereby significantly improving both the therapeutic index and the efficacy of hepatocellular carcinoma killing by fluorocytosine.
Graepler
Florian
F
Department of Internal Medicine I, Medical University Clinic Tübingen, Germany. florian.graepler@uni-tuebingen.de
Lemken
Marie-Luise
ML
Wybranietz
Wolfgang A
WA
Schmidt
Ulrike
U
Smirnow
Irina
I
Gross
Christine D
CD
Spiegel
Martin
M
Schenk
Andrea
A
Graf
Hansjörg
H
Lauer
Ulrike A
UA
Vonthein
Reinhard
R
Gregor
Michael
M
Armeanu
Sorin
S
Bitzer
Michael
M
Lauer
Ulrich M
UM
D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000378:metabolism / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D043525:Cytosine Deaminase / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D005437:Flucytosine / Q000378:metabolism / Q000627:therapeutic use*; D041722:Genes, Transgenic, Suicide; D015316:Genetic Therapy; D008113:Liver Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000628:therapy*; D008114:Liver Neoplasms, Experimental / Q000188:drug therapy / Q000473:pathology / Q000628:therapy*; D008279:Magnetic Resonance Imaging; D009368:Neoplasm Transplantation; D010430:Pentosyltransferases / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
D000964:Antimetabolites, Antineoplastic; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D005437:Flucytosine; D010430:Pentosyltransferases; C023269:uracil phosphoribosyltransferase; D043525:Cytosine Deaminase