Increasing specificity of anti-tumor therapy: cytotoxic protein delivery by non-pathogenic clostridia under regulation of radio-induced promoters.
BACKGROUND
Pathogenic clostridia, genetically engineered to express therapeutic genes, will specifically target hypoxic regions in tumors. This specificity can be further improved if expression of these genes is controlled by a radio-induced promoter, leading to spatial and temporal control of gene expression.


METHODS
Following administration of Clostridium spores to tumor bearing rats, normal tissue and tumoral specimens were compared for colonization. Clostridium was genetically modified to express tumor necrosis factor a or cytosine deaminase. Expression of these proteins was assayed. Northern blot hybridizations were used to detect genes which are radio-induced.


RESULTS
Clostridium gave a selective colonization of tumors. The recombinant clostridia expressed in vitro and in vivo TNF alpha and cytosine deaminase. Clostridial SOS-repair genes were induced at a dose of 2 Gy.


CONCLUSIONS
Pathogenic Clostridium can be used for tumor specific delivery of therapeutic genes. The specificity can be improved via radio-induced promoters. Overall, this new gene delivery system can lead to an increase of the therapeutic ratio in cancer treatment.
Nuyts
S
S
Laboratory of Experimental Radiobiology, University Hospital Gasthuisberg, Herestraat 49, 3000 Leuven, Belgium. Sandra.Nuyts@rega.kuleuven.ac.be
Theys
J
J
Landuyt
W
W
van Mellaert
L
L
Lambin
P
P
Anné
J
J
D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D001426:Bacterial Proteins / Q000235:genetics; D002480:Cellulase / Q000235:genetics*; D003013:Clostridium / Q000235:genetics; D043525:Cytosine Deaminase; D004262:DNA Restriction Enzymes; D003851:Deoxyribonucleases / Q000235:genetics; D016503:Drug Delivery Systems; D005437:Flucytosine; D005472:Fluorouracil; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics; D008297:Male; D009700:Nucleoside Deaminases / Q000008:administration & dosage / Q000235:genetics* / Q000627:therapeutic use; D011401:Promoter Regions, Genetic; D051381:Rats; D011938:Rec A Recombinases / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage / Q000235:genetics* / Q000627:therapeutic use
D000970:Antineoplastic Agents; D001426:Bacterial Proteins; D014409:Tumor Necrosis Factor-alpha; D005437:Flucytosine; D011938:Rec A Recombinases; D003851:Deoxyribonucleases; D004262:DNA Restriction Enzymes; C047879:RecN protein, Bacteria; D002480:Cellulase; D009700:Nucleoside Deaminases; D043525:Cytosine Deaminase; D005472:Fluorouracil