Molecular chemotherapy of pancreatic cancer using novel mutant bacterial cytosine deaminase gene.

Abstract

The combination of molecular chemotherapy with radiation therapy has the potential to become a powerful approach for treatment of pancreatic cancer. We have developed an adenoviral vector (AdbCD-D314A) encoding a mutant bacterial cytosine deaminase (bCD) gene, which converts the prodrug 5-fluorocytosine (5-FC) into the active drug 5-fluorouracil. The aim of this study was to investigate AdbCD-D314A/5-FC-mediated cytotoxicity in vitro and therapeutic efficacy in vivo alone and in combination with radiation against human pancreatic cancer cells and xenografts. AdbCD-D314A/5-FC-mediated cytotoxicity alone and in combination with radiation was analyzed using crystal violet inclusion and clonogenic survival assays. CD enzyme activity was determined by measuring conversion of [3H]5-FC to [3H]5-fluorouracil after adenoviral infection of pancreatic cancer cells in vitro and pancreatic tumor xenografts by TLC. S.c. pancreatic tumor xenografts were used to evaluate the therapeutic efficacy of AdbCD-D314A/5-FC molecular chemotherapy in combination with radiation therapy. AdbCD-D314A infection resulted in increased 5-FC-mediated pancreatic cancer cell killing that correlated with significantly enhanced CD enzyme activity compared with AdbCDwt encoding wild-type of bCD. Animal studies showed significant inhibition of growth of human pancreatic tumors treated with AdbCD-D314A/5-FC in comparison with AdbCDwt/5-FC. Also, a significantly greater inhibition of growth of Panc2.03 and MIA PaCA-2 tumor xenografts was produced by the combination of AdbCD-D314A/5-FC with radiation compared with either agent alone. The results indicate that the combination of AdbCD-D314A/5-FC molecular chemotherapy with radiation therapy significantly enhanced cytotoxicity of pancreatic cancer cells in vitro and increased therapeutic efficacy against human pancreatic tumor xenografts.

• Authors: Lyudmila N Kaliberova, Debbie L Della Manna, Valentina Krendelchtchikova, Margaret E Black, Donald J Buchsbaum, Sergey A Kaliberov
• Journal: Molecular cancer therapeutics (Mol Cancer Ther) Vol. 7 Issue 9 Pg. 2845-54 (Sep 2008) ISSN: 1535-7163 [Print] United States
• PMID: 18790765 (Publication Type: Journal Article)

Chemical References

• Apoptosis Regulatory Proteins
• Mutant Proteins
• Flucytosine
• Cytosine Deaminase

Topics

• Adenoviridae
• Amino Acid Substitution (drug effects, radiation effects)
• Animals
• Apoptosis Regulatory Proteins (metabolism)
• Cell Death (drug effects, radiation effects)
• Cell Line, Tumor
• Colony-Forming Units Assay
• Cytosine Deaminase (genetics, therapeutic use)
• Escherichia coli (enzymology)
• Female
• Flucytosine (pharmacology)
• Genetic Therapy
• Humans
• Mice
• Mice, Nude
• Mutant Proteins (therapeutic use)
• Pancreatic Neoplasms (drug therapy, genetics, radiotherapy, therapy)
• Radiation, Ionizing
• Xenograft Model Antitumor Assays